Synthesis and Characterization of A Coordination Complex of Tetrakis(diphenylamine)copper(II) Sulfate Hexahydrate

NASA Astrophysics Data System (ADS)

Syaima, H.; Rahardjo, S. B.; Suciningrum, E.

2018-03-01

CuSO4·5H2O with diphenylamine formed a complex compound in 1:4 mole ratio of metal to the ligand in methanol. The forming of the complex was indicated by shifting of UV-Vis spectra of CuSO4·5H2O and the complex from 819 nm to 593 nm. The result of analysis Cu(II) in the complex showed the copper content in the complex was 6.43 % therefore the empirical formula of the complex was Cu(diphenylamine)4SO4(H2O)6. The electrical conductivity of complex showed the charge ratio of cation and anion = 1:1. Therefore, the proposed formula of the complex was [Cu(diphenylamine)4]SO4·6H2O. Based on infrared spectra, it was determined that the functional group of N-H of diphenylamine was coordinated to the center ion Cu2+. The electronic spectral study of the complex showed a transition peak on λ = 593 nm (υ = 16863 cm-1) corresponding to the 2B1g → 2A1g transition. The complex was paramagnetic with effective magnetic moment 1.72 B.M. It was indicated square planar geometry around Cu(II).

Minimising reversion, using seawater and magnesium chloride, caused by the dissolution of tricalcium aluminate hexahydrate.

PubMed

Palmer, Sara J; Frost, Ray L; Smith, Matthew K

2011-01-15

The increase in pH and aluminium concentration after the neutralisation of bauxite refinery residues is commonly known as reversion. This investigation reports the extent of reversion in synthetic supernatant liquor and possible methods to reduce reversion. This work is based on bauxite refinery residues produced from alumina refineries, where reversion is a real life situation in neutralised refinery residues. Tricalcium aluminate hexahydrate, a common phase in bauxite refinery residues, has been found to cause reversion. It has been established that reductions in both pH and aluminium from the seawater neutralisation process are due to the formation of 'Bayer' hydrotalcite Mg(7)Al(2)(OH)(18)(CO(3)(2-),SO(4)(2-))·xH(2)O. This is the primary mechanism involved in the removal of aluminium from solution. Increasing the volume of seawater used for the neutralisation process minimises the extent of reversion for both synthetic supernatant liquor and red mud slurry. The addition of MgCl(2)·6H(2)O also showed a reduction in reversion and confirmed that the decrease in aluminium and hydroxyl ions is due to the formation of Bayer hydrotalcite and not simply a dilution effect. Copyright © 2010 Elsevier Inc. All rights reserved.

Phase Transformation, Surface Morphology and Dielectric Property of P(VDF-HFP)/MgCl2·6H2O Nanocomposites

NASA Astrophysics Data System (ADS)

Yuennan, J.; Sukwisute, P.; Boripet, B.; Muensit, N.

2017-09-01

Nanocomposite piezoelectric films based on the blend of poly(vinylidenefluoride-hexafluoropropylene) (PVDF-HFP) and magnesium chloride hexahydrate (MgCl2•6H2O) have been investigated in this work. The films incorporated with 0.5 wt% MgCl2•6H2O were prepared using a solution casting technique and uniaxially stretched at various ratios from 2 to 6 times in order to characterize phase transformation, surface morphology and dielectric behaviour. The piezoelectric β phase transformation and crystallinity of the stretched films were identified by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). A scanning electron microscopy (SEM) was conducted to observe the surface microstructure and porosity. The frequency dependence of dielectric properties was also measured by LCR meter at room temperature. The stretched films show the larger the stretching ratio, the greater the microdefects appearance. This leads to a decrease of dielectric constant with stretching ratio. Nevertheless, the P(VDF-HFP) nanocomposites with stretching ratio of 4 times display a higher β phase fraction of 90% than the unstretched films. Thus, this result points out that the β phase transformation of the composite films can be enhanced by mechanically stretching process.

Two actinide-organic frameworks constructed by a tripodal flexible ligand: Occurrence of infinite {(UO2)O2(OH)3}4n and hexanuclear {Th6O4(OH)4} motifs

NASA Astrophysics Data System (ADS)

Liang, Lingling; Zhang, Ronglan; Zhao, Jianshe; Liu, Chiyang; Weng, Ng Seik

2016-11-01

Two new actinide metal-organic frameworks were constructed by using a tripodal flexible ligand tris (2-carboxyethyl) isocyanurate (H3tci) under hydrothermal condition. The combination of H3tci and uranyl nitrate hexahydrate in aqueous solution leads to the isolation of [(UO2)2(H2O)4]0.5(tci)2(UO2)4(OH)4·18H2O (1), which contains two distinct UO22+ coordination environments. Four uranyl cations, linked through μ3-OH respectively, result in the edge-sharing ribbons. Then, the layer structure is constructed by U-O clusters linked through other eight-coordinated uranyl unions, giving rise to a porous structure in the space. Topological analysis reveals that complex 1 belongs to a (4, 8)-connected net with a schläfli symbol of (34.26.3)2(34.46.56.68.73.8). Th3(tci)2O2(OH)2(H2O)3·12H2O (2) generated by the reaction of H3tci and thorium nitrate tetrahydrate, possesses nine-fold coodinated Th(IV) centers with a monocapped square antiprismatic geometry. The hexamers "Th6O4(OH)4" motifs are connected together by the carboxylate groups, showing a three-dimensional structures. Complex 2 takes on an 8-connected architecture and the point symbol is (424.64).

Two actinide-organic frameworks constructed by a tripodal flexible ligand: Occurrence of infinite ((UO{sub 2})O{sub 2}(OH){sub 3}){sub 4n} and hexanuclear (Th{sub 6}O{sub 4}(OH){sub 4}) motifs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liang, Lingling; Zhang, Ronglan; Zhao, Jianshe, E-mail: jszhao@nwu.edu.cn

Two new actinide metal-organic frameworks were constructed by using a tripodal flexible ligand tris (2-carboxyethyl) isocyanurate (H{sub 3}tci) under hydrothermal condition. The combination of H{sub 3}tci and uranyl nitrate hexahydrate in aqueous solution leads to the isolation of [(UO{sub 2}){sub 2}(H{sub 2}O){sub 4}]{sub 0.5}(tci){sub 2}(UO{sub 2}){sub 4}(OH){sub 4}·18H{sub 2}O (1), which contains two distinct UO{sub 2}{sup 2+} coordination environments. Four uranyl cations, linked through μ{sub 3}-OH respectively, result in the edge-sharing ribbons. Then, the layer structure is constructed by U-O clusters linked through other eight-coordinated uranyl unions, giving rise to a porous structure in the space. Topological analysis reveals thatmore » complex 1 belongs to a (4, 8)-connected net with a schläfli symbol of (3{sup 4.}2{sup 6.}3){sub 2}(3{sup 4.}4{sup 6.}5{sup 6.}6{sup 8.}7{sup 3.}8). Th{sub 3}(tci){sub 2}O{sub 2}(OH){sub 2}(H{sub 2}O){sub 3}·12H{sub 2}O (2) generated by the reaction of H{sub 3}tci and thorium nitrate tetrahydrate, possesses nine-fold coodinated Th(IV) centers with a monocapped square antiprismatic geometry. The hexamers “Th{sub 6}O{sub 4}(OH){sub 4}” motifs are connected together by the carboxylate groups, showing a three-dimensional structures. Complex 2 takes on an 8-connected architecture and the point symbol is (4{sup 24.}6{sup 4}). - Graphical abstract: Two new 3D actinide metal-organic frameworks were constructed by using a tripodal flexible ligand tris (2-carboxyethyl) isocyanurate (H3tci) and their topological structures were displayed. The infinite ((UO{sub 2})O{sub 2}(OH){sub 3}){sub 4n} and hexanuclear (Th{sub 6}O{sub 4}(OH){sub 4}) motifs were found in the title actinides networks.« less

Supramolecular architectures constructed by lanthanum, amino acids and 1,10-phenanthroline via non-covalent bond interactions

NASA Astrophysics Data System (ADS)

Zheng, Xiang-Jun; Jin, Lin-Pei

2003-07-01

Three supramolecular lanthanum coordination compounds of amino acids, with 1,10-phenanthroline (phen), [La 2(APA) 6(phen) 2(H 2O) 2](ClO 4) 6(phen) 4·2H 2O ( 1), [La 2(ABA) 6(phen) 2(H 2O) 2](ClO 4) 6 (phen) 6·4H 2O ( 2), and [La 2(AHA) 4(phen) 4](ClO 4) 6(phen) 4·2H 2O ( 3) (APA=3-aminopropionic acid; ABA=4-aminobutanoic acid; AHA=6-aminohexanoic acid) were synthesized and characterized by single crystal X-ray diffraction. The results show that the three coordination compounds are all composed of binuclear coordination cations built by metal-ligand coordination. Through hydrogen bonding and π-π stacking interactions, complex 1 forms a two-dimensional supramolecular sheet structure extending in the (001) plane, complex 2 forms a three-dimensional supramolecular network with many cavities occupied by ClO 4- and lattice H 2O molecules, and complex 3 forms a two-dimensional supramolecular lamellar structure in the (100) plane.

Synthesis and Elucidation Structure of Tetrakis-diphenylaminecopper(II) Chloride Hexahydrate

NASA Astrophysics Data System (ADS)

Syaima, H.; Rahardjo, S. B.; Suciningrum, E.

2017-11-01

CuCl2·2H2O with diphenylamine formed a complex compound in 1:4-mole ratio of metal to the ligand in methanol. Its structural properties were investigated by employing metal content analysis by Atomic Absorption Spectroscopy (AAS), magnetic susceptibility, UV-vis and FTIR spectroscopy. The forming of the complex was indicated by shifting of UV-Vis spectra. The result of analysis Cu(II) in the complex showed empirical formula of the complex were Cu(diphenylamine)4Cl2(H2O)6. The electrical conductivity of complex showed the charge ratio of cation and anion = 2:1. Finally, the proposed formula of the complex was [Cu(diphenylamine)4]Cl2·6H2O. Based on infrared spectra, it was revealed that diphenylamine existed as monodentate bind to copper(II) through the functional group of N-H. The electronic spectral study of the complex showed three transition peaks on 861, 592, and 419 nm corresponding to the 2B1g → 2A1g, 2B1g → 2B2g dan 2B1g → 2Eg transitions. The complex was paramagnetic and indicated that ligands form square planar geometry around the Cu(II).

A Family of Uranyl Coordination Polymers Containing O-Donor Dicarboxylates and Trispyridyltriazine Guests

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thangavelu, Sonia G.; Cahill, Christopher L.

Four uranyl coordination polymers [UO2(C6H8O4)(H2O)2](C18H12N6)2 (1), [UO2(C8H4O4)(H2O)2](C18H12N6)2 (2), Na[(UO2)(C12H6O4)2](C18H13N6)·H2O (3), and Na[(UO2)(C16H8O4)(C6H3NO2)](C18H12N6)·H2O (4) containing aliphatic (adipic acid) or aromatic linkers (1,4-benzene dicarboxylic acid (BDC), 1,4-napthalene dicarboxylic acid (NDC), anthracene 9,10-dicarboxylic acid (ADC)) were synthesized and characterized using single crystal X-ray diffraction, powder X-ray diffraction, and luminescence spectroscopy. The π-stacking distances or the number of π–π interactions present between trispyridyltriazine (TPTZ) guests or the host framework in 1–4 may be affected by the size of the O-donor linker (adipic acid < BDC < NDC < ADC). Luminescence studies show that substitution between adipic acid and BDC influences the emission of 1more » and 2, in which the emission of 1 shows a red shift relative to that of 2. Uranyl emission was not observed in 3 and 4, and may be attributed to the position of the NDC and ADC triplet state relative to the emissive uranyl species.« less

A Family of Uranyl Coordination Polymers Containing O-Donor Dicarboxylates and Trispyridyltriazine Guests

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thangavelu, Sonia G.; Cahill, Christopher L.

2016-01-06

Four uranyl coordination polymers [UO2(C6H8O4)(H2O)2](C18H12N6)2 (1), [UO2(C8H4O4)(H2O)2](C18H12N6)2 (2), Na[(UO2)(C12H6O4)2](C18H13N6)·H2O (3), and Na[(UO2)(C16H8O4)(C6H3NO2)](C18H12N6)·H2O (4) containing aliphatic (adipic acid) or aromatic linkers (1,4-benzene dicarboxylic acid (BDC), 1,4-napthalene dicarboxylic acid (NDC), anthracene 9,10-dicarboxylic acid (ADC)) were synthesized and characterized using single crystal X-ray diffraction, powder X-ray diffraction, and luminescence spectroscopy. The π-stacking distances or the number of π–π interactions present between trispyridyltriazine (TPTZ) guests or the host framework in 1–4 may be affected by the size of the O-donor linker (adipic acid < BDC < NDC < ADC). Luminescence studies show that substitution between adipic acid and BDC influences the emission of 1more » and 2, in which the emission of 1 shows a red shift relative to that of 2. Uranyl emission was not observed in 3 and 4, and may be attributed to the position of the NDC and ADC triplet state relative to the emissive uranyl species.« less

An Efficient, Solvent-Free Process for Synthesizing Anhydrous MgCl 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Motkuri, Radha K.; Vemuri, Venkata Rama S.; Barpaga, Dushyant

A new efficient and solvent-free method for the synthesis of anhydrous MgCl2 from its hexahydrate is proposed. Fluidized dehydration of MgCl 2·6H 2O feedstock at 200 °C in a porous bed reactor yields MgCl2·nH2O (0 < n < 1), which has a similar diffraction pattern as activated MgCl2. The MgCl 2·nH 2O is then ammoniated directly using liquefied NH 3 in the absence of solvent to form MgCl 2·6NH 3. Calcination of the hexammoniate complex at 300 °C then yields anhydrous MgCl 2. Both dehydration and deammoniation were thoroughly studied using in situ as well as ex situ characterization techniques.more » Specifically, a detailed understanding of the dehydration process was monitored by in situ PXRD and in situ FTIR techniques where formation of salt with nH 2O (n = 4, 2, 1, <1) was characterized. Given the reduction in thermal energy required to produce dehydrated feedstock with this method compared with current strategies, significant cost benefits are expected. Overall, the combined effect of activation, macroporosity, and coordinated water depletion allows the formation of hexammoniate without using solvent, thus minimizing waste formation.« less

Efficient conversion of brown grease produced by municipal wastewater treatment plant into biofuel using aluminium chloride hexahydrate under very mild conditions.

PubMed

Pastore, Carlo; Lopez, Antonio; Mascolo, Giuseppe

2014-03-01

Wastes produced by oil/water separation at the wastewater treatment plant of Bari West (Southern Italy) were taken, characterized and converted. About 12% of this material was composed of greases, mainly made of free fatty acids (50%) and soaps (34%), and was easily separable by the aqueous phase through a hot centrifugation. After chemical activation of this fatty fraction, a direct esterification was carried out under very mild conditions (320K and atmospheric pressure), converting more than 90% of the original free fatty acids into the respective methyl esters in less than 4h, by using AlCl3·6H2O. The activation energy correlated to the use of this catalyst was also calculated (Eaest=43.9kJmol(-1)). The very low cost of the biodiesel produced (0.45€L(-1)) and the associated relevant specific energy (5.02MJ kgFAMEs(-1)) make such a process a really sustainable and effective example of valorization of a waste. Copyright © 2013 Elsevier Ltd. All rights reserved.

Theoretical studies of the EPR parameters and local structures for Cu2+-doped cobalt ammonium phosphate hexahydrate

NASA Astrophysics Data System (ADS)

Li, Chao-Ying; Liu, Shi-Fei; Fu, Jin-Xian

2015-11-01

High-order perturbation formulas for a 3d9 ion in rhombically elongated octahedral was applied to calculate the electron paramagnetic resonance (EPR) parameters (the g factors, gi, and the hyperfine structure constants Ai, i = x, y, z) of the rhombic Cu2+ center in CoNH4PO4.6H2O. In the calculations, the required crystal-field parameters are estimated from the superposition model which enables correlation of the crystal-field parameters and hence the EPR parameters with the local structure of the rhombic Cu2+ center. Based on the calculations, the ligand octahedral (i.e. [Cu(H2O)6]2+ cluster) are found to experience the local bond length variations ΔZ (≈0.213 Å) and δr (≈0.132 Å) along axial and perpendicular directions due to the Jahn-Teller effect. Theoretical EPR parameters based on the above local structure are in good agreement with the observed values; the results are discussed.

Electrodeposition mechanism of quaternary compounds Cu2ZnSnS4: Effect of the additives

NASA Astrophysics Data System (ADS)

Tang, Aiyue; Li, Zhilin; Wang, Feng; Dou, Meiling; Liu, Jingjun; Ji, Jing; Song, Ye

2018-01-01

The electrodeposition mechanism of pure phase Cu2ZnSnS4 (CZTS) thin film with subsequent annealing was investigated in detail. An electrolyte design principle of quaternary compounds was proposed. The complex ions of Cu(H2C6H5O7)+, Cu2(C6H5O7)+, Zn(C4H5O6)+, Sn(H2C6H5O7)+ and Sn2(C6H5O7)+, which influenced the reduction process and played important roles in co-deposition, were identified by UV spectra. Electrochemical studies indicated that trisodium citrate and tartaric acid could narrow the co-deposition potential range of the four elements to -0.8 V to -1.2 V (vs. SCE). The cause was the synergetic effect that trisodium citrate inhibited the reduction of Cu2+ and Sn2+ and tartaric acid promoted the reduction of Zn2+. The reduction of S2O32- was mainly attributed to the induction effect of the metallic ions, and the H+ dissociated from tartaric acid could also promote the cathode process of S2O32-. The reaction mechanism could be summarized as the following steps: (I) Cu(H2C6H5O7)+, Cu2(C6H5O7)+ → Cu, Sn(H2C6H5O7)+, Sn2(C6H5O7)+ → Sn, Zn(C4H5O6)+ → Zn; (II) the desorption of (H2C6H5O7)- and (C6H5O7)-, and the reduction of S2O32- induced by metallic ions and H+. The mechanism studies provided a path of electrolyte design for multicomponent compounds.

Thermophysical Characterization of MgCl₂·6H₂O, Xylitol and Erythritol as Phase Change Materials (PCM) for Latent Heat Thermal Energy Storage (LHTES).

PubMed

Höhlein, Stephan; König-Haagen, Andreas; Brüggemann, Dieter

2017-04-24

The application range of existing real scale mobile thermal storage units with phase change materials (PCM) is restricted by the low phase change temperature of 58 ∘ C for sodium acetate trihydrate, which is a commonly used storage material. Therefore, only low temperature heat sinks like swimming pools or greenhouses can be supplied. With increasing phase change temperatures, more applications like domestic heating or industrial process heat could be operated. The aim of this study is to find alternative PCM with phase change temperatures between 90 and 150 ∘ C . Temperature dependent thermophysical properties like phase change temperatures and enthalpies, densities and thermal diffusivities are measured for the technical grade purity materials xylitol (C 5 H 12 O 5 ), erythritol (C 4 H 10 O 4 ) and magnesiumchloride hexahydrate (MCHH, MgCl 2 · 6H 2 O). The sugar alcohols xylitol and erythritol indicate a large supercooling and different melting regimes. The salt hydrate MgCl 2 · 6H 2 O seems to be a suitable candidate for practical applications. It has a melting temperature of 115.1 ± 0.1 ∘ C and a phase change enthalpy of 166.9 ± 1.2 J / g with only 2.8 K supercooling at sample sizes of 100 g . The PCM is stable over 500 repeated melting and solidification cycles at differential scanning calorimeter (DSC) scale with only small changes of the melting enthalpy and temperature.

40 CFR 721.9511 - Silicic acid (H6SiO2O7), magnesium, strontium salt(1:1:2), dysprosium and europium-doped.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Silicic acid (H6SiO2O7), magnesium...), magnesium, strontium salt(1:1:2), dysprosium and europium-doped. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as silicic acid (H6SiO2O7) magnesium...

40 CFR 721.9511 - Silicic acid (H6SiO2O7), magnesium, strontium salt(1:1:2), dysprosium and europium-doped.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Silicic acid (H6SiO2O7), magnesium...), magnesium, strontium salt(1:1:2), dysprosium and europium-doped. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as silicic acid (H6SiO2O7) magnesium...

40 CFR 721.9511 - Silicic acid (H6SiO2O7), magnesium, strontium salt(1:1:2), dysprosium and europium-doped.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Silicic acid (H6SiO2O7), magnesium...), magnesium, strontium salt(1:1:2), dysprosium and europium-doped. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as silicic acid (H6SiO2O7) magnesium...

40 CFR 721.9511 - Silicic acid (H6SiO2O7), magnesium, strontium salt(1:1:2), dysprosium and europium-doped.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Silicic acid (H6SiO2O7), magnesium...), magnesium, strontium salt(1:1:2), dysprosium and europium-doped. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as silicic acid (H6SiO2O7) magnesium...

Thermophysical Characterization of MgCl2·6H2O, Xylitol and Erythritol as Phase Change Materials (PCM) for Latent Heat Thermal Energy Storage (LHTES)

PubMed Central

Höhlein, Stephan; König-Haagen, Andreas; Brüggemann, Dieter

2017-01-01

The application range of existing real scale mobile thermal storage units with phase change materials (PCM) is restricted by the low phase change temperature of 58 ∘C for sodium acetate trihydrate, which is a commonly used storage material. Therefore, only low temperature heat sinks like swimming pools or greenhouses can be supplied. With increasing phase change temperatures, more applications like domestic heating or industrial process heat could be operated. The aim of this study is to find alternative PCM with phase change temperatures between 90 and 150 ∘C. Temperature dependent thermophysical properties like phase change temperatures and enthalpies, densities and thermal diffusivities are measured for the technical grade purity materials xylitol (C5H12O5), erythritol (C4H10O4) and magnesiumchloride hexahydrate (MCHH, MgCl2·6H2O). The sugar alcohols xylitol and erythritol indicate a large supercooling and different melting regimes. The salt hydrate MgCl2·6H2O seems to be a suitable candidate for practical applications. It has a melting temperature of 115.1 ± 0.1 ∘C and a phase change enthalpy of 166.9 ± 1.2 J/g with only 2.8 K supercooling at sample sizes of 100 g. The PCM is stable over 500 repeated melting and solidification cycles at differential scanning calorimeter (DSC) scale with only small changes of the melting enthalpy and temperature. PMID:28772806

Growth and structural analysis of ammonium nickel cobalt sulfate hexahydrate crystals

NASA Astrophysics Data System (ADS)

de Oliveira, Michelle; Ghosh, Santunu; Pacheco, Tiago S.; Perpétuo, Genivaldo J.; Franco, Carlos J.

2017-10-01

We have obtained a set of crystals of the empirical formula (NH4)2Ni x Co(1-x)(SO4)2 · 6H2O with the different concentrations of Ni and Co, by employing the growth from the solution technique. We have chosen the monocrystal (NH4)2Ni0.3Co0.7(SO4)2 · 6H2O for the structural analysis. The structure was resolved by x-ray diffraction method and refined by the full-matrix least-squares method with the help of SHELXS software. This crystal belongs to a monoclinic space group P21/c with crystal parameters, a  =  6.2455 (2) Å, b  =  12.5065 (3) Å, c  =  9.2303 (2) Å, α  =  γ  =  90°, β  =  106.995 (3)°, V  =  689.49 (3) Å3, Z  =  2. We have shown the configuration of the unit cell of the above monocrystal, along with that we have also reported the length, angles between the bonds and the geometry of the hydrogen bonds of the monocrystal.

Concentrating molasses distillery wastewater using biomimetic forward osmosis (FO) membranes.

PubMed

Singh, N; Petrinic, I; Hélix-Nielsen, C; Basu, S; Balakrishnan, M

2018-03-01

Treatment of sugarcane molasses distillery wastewater is challenging due to the presence of complex phenolic compounds (melanoidins and polyphenols) having antioxidant properties. Due to zero liquid discharge regulations, Indian distilleries continue to explore effective treatment options. This work examines the concentration of distillery wastewater by forward osmosis (FO) using aquaporin biomimetic membranes and magnesium chloride hexahydrate (MgCl 2 .6H 2 O) as draw solution. The operational parameters viz. feed solution and draw solution flow rate and draw solution concentration were optimized using 10% v/v melanoidins model feed solution. This was followed by trials with distillery wastewater. Under the conditions of this work, feed and draw flow rates of 1 L/min and draw solution concentration of 2M MgCl 2 .6H 2 O for melanoidins model solution and 3M MgCl 2 .6H 2 O for distillery wastewater were optimal for maximum rejection. Rejection of 90% melanoidins, 96% antioxidant activity and 84% COD was obtained with melanoidins model feed, with a corresponding water flux of 6.3 L/m 2 h. With as-received distillery wastewater, the rejection was similar (85-90%) to the melanoidins solution, but the water flux was lower (2.8 L/m 2 h). Water recovery from distillery wastewater over 24 h study period was higher with FO (70%) than reported for RO (35-45%). Repeated use of the FO membrane over five consecutive 24 h cycles with fresh feed and draw solutions and periodic cleaning showed consistent average water flux and rejection of the feed constituents. Copyright © 2017 Elsevier Ltd. All rights reserved.

One-step synthesis and characterizations of cerium oxide nanoparticles in an ambient temperature via Co-precipitation method

NASA Astrophysics Data System (ADS)

Pujar, Malatesh S.; Hunagund, Shirajahammad M.; Desai, Vani R.; Patil, Shivaprasadgouda; Sidarai, Ashok H.

2018-04-01

We report the simple Co-precipitation method for the synthesis of Cerium oxide (CeO2) nanoparticles (NPs) in an ambient temperature. We have taken the Cerium (III) nitrate hexahydrate (Ce(NO3)3.6H2O) and Sodium hydroxide (NaOH) as the precursors. The obtained NPs were analyzed using the UV-Vis spectrophotometer, Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). The obtained results signify that UV-Vis spectrum exhibited a well-defined absorption peak at 274 nm and the estimated energy gap (Eg) is 4.05 eV. The FT-IR analysis provides the supporting evidence for the presence of bonding of O-H, nitrates, alcohols and O-Ce-O vibrations. The XRD result reveals that the synthesized CeO2 NPs was crystallite with cubic phase structure and the estimated average crystallite size of CeO2 NPs using Scherer's and W-H method was significantly different due to their assumptions. Further, it is purposed to study their photocatalytic biological activities.

Syntheses and characterizations of secondary Pb-O bonding supported Pb(II)-sulfonate complexes

NASA Astrophysics Data System (ADS)

Huang, Guo-Zhen; Zou, Xin; Zhu, Zhi-Biao; Deng, Zhao-Peng; Huo, Li-Hua; Gao, Shan

2018-06-01

The reaction of Pb(II) salts and mono- or disulfonates leads to the formation of eight new Pb(II)-mono/disulfonate complexes, [Pb(L1)(H2O)]2 (1), [Pb4(L2)2(AcO)2]n·5nH2O (2), [Pb(L3)(H2O)]2 (3), [Pb(HL4)(H2O)2]n·nH2O (4), [Pb(HL5)(H2O)2]n·2nH2O (5), [Pb(H2L6)(H2O)]n·nDMF·2nH2O (6), [Pb2(H3L7)4(H2O)6]·2H2O (7) and [Pb(H2L7)(H2O)]n·nH2O (8) (H2L1= 2-hydroxy-5-methyl-benzenesulfonic acid, H3L2= 2-hydroxyl-5-methyl- 1,3-benzenedisulfonic acid, H2L3= 2-hydroxy-5-nitro-benzenesulfonic acid, H3L4= 2-hydroxyl-5-bromo-1,3- benzenedisulfonic acid, H3L5= 2-hydroxyl-5-carboxyl-benzenesulfonic acid, H4L6= 2,5-dihydroxyl-3-carboxyl- benzenesulfonic acid, H4L7= 2,4-dihydroxyl-5-carboxyl-benzenesulfonic acid, DMF = N,N'-dimethyl-formamide, AcO- = acetate), which have been characterized by elemental analysis, IR, TG, PL, powder and single-crystal X-ray diffraction. In view of the primary Pb-O bonds, these eight complexes exhibit diverse dinuclear (1, 3 and 7), helical chain (4), wave-like chain (5), linear chain (6), zigzag chain (8) and layer structure (2), in which the Pb(II) cations present different hemi-directed geometries. Taking the secondary Pb-O bonds into account, chain structure for complex 7, layer motifs for complexes 1 and 3-6, as well as 3-D framework for complex 8 are observed with Pb(II) cations showing more intricate holo-directed geometries. The various coordination modes of these seven different mono/disulfonate anions are responsible for the formation of these multiple structures. Furthermore, the introduction of hydroxyl and carboxyl groups increases the coordination ability of sulfonate to the p-block metal cation. Luminescent analyses indicate that complex 7 presents purple emission at 395 nm at room temperature.

One Step Synthesis of NiO Nanoparticles via Solid-State Thermal Decomposition at Low-Temperature of Novel Aqua(2,9-dimethyl-1,10-phenanthroline)NiCl2 Complex

PubMed Central

Barakat, Assem; Al-Noaimi, Mousa; Suleiman, Mohammed; Aldwayyan, Abdullah S.; Hammouti, Belkheir; Ben Hadda, Taibi; Haddad, Salim F.; Boshaala, Ahmed; Warad, Ismail

2013-01-01

[NiCl2(C14H12N2)(H2O)] complex has been synthesized from nickel chloride hexahydrate (NiCl2·6H2O) and 2,9-dimethyl-1,10-phenanthroline (dmphen) as N,N-bidentate ligand. The synthesized complex was characterized by elemental analysis, infrared (IR) spectroscopy, ultraviolet-visible (UV-vis) spectroscopy and differential thermal/thermogravimetric analysis (TG/DTA). The complex was further confirmed by single crystal X-ray diffraction (XRD) as triclinic with space group P-1. The desired complex, subjected to thermal decomposition at low temperature of 400 ºC in an open atmosphere, revealed a novel and facile synthesis of pure NiO nanoparticles with uniform spherical particle; the structure of the NiO nanoparticles product was elucidated on the basis of Fourier transform infrared (FT-IR), UV-vis spectroscopy, TG/DTA, XRD, scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDXS) and transmission electron microscopy (TEM). PMID:24351867

Influence of boric acid (H3BO3) concentration on the physical properties of electrochemical deposited nickel (Ni) nanowires

NASA Astrophysics Data System (ADS)

Kananathan, J.; Sofiah, A. G. N.; Samykano, M.; Ulakanathan, S.; Lah, N. A. C.; Harun, W. S. W.; Sudhakar, K.; Kadirgama, K.; Ngui, W. K.; Siregar, J. P.

2017-10-01

Authors have investigated the influence of the stabilizer (Boric Acid) concentration during the template-assisted electrochemical deposition of Nickel (Ni) nanowires in Anodic Alumina Oxide (AAO) templates. The synthesis was performed using Ni Sulfate Hexahydrate (NiSO4.6H2O) as metal salts and Boric Acid (H3BO3) as a stabilizer. The mixture of both solutions creates electrolyte and utilized for the electrochemical deposition of Ni nanowires. During the experiment, the boric acid concentration varied between 5 g/L, 37.5 g/L and 60 g/L with a deposition temperature of 80 °C (constant). After the electrochemical deposition process, AAO templates were cleaned with distilled water before dissolution in Sodium Hydroxide (NaOH) solution to obtain the freestanding Ni nanowires. Physical properties of the synthesized Ni nanowires were analyzed using Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive Spectroscopy (EDX) and X-ray Diffraction (XRD). The physical properties of obtained Ni nanowires has eloborated by taking into account the effect of boric acid concentration on the surface morphology, growth length, elemental composition and crystal orientation crystal of the synthesized nickel nanowires. The finding exposes that the boric acid concentration does not influence all aspects in the physicals properties of the synthesized Ni nanowires. The boric acid concentration did not affect the surface texture and crystal orientation. However, shorter Ni nanowires obtained as the concentration of boric acid increased.

Structures, vibrational frequencies, and infrared spectra of the hexa-hydrated benzene clusters

NASA Astrophysics Data System (ADS)

Lee, Jin Yong; Kim, Jongseob; Lee, Han Myoung; Tarakeshwar, P.; Kim, Kwang S.

2000-10-01

The water hexamer is known to have a number of isoenergetic structures. The first experimental identification of the O-H stretching vibrational spectra of the water hexamer was done in the presence of benzene. It was followed by the identification of the pure water hexamer structure by vibration-rotational tunneling (VRT) spectroscopy. Although both experiments seem to have located only the Cage structure, the structure of the benzene-water hexamer complex is not clearly known, and the effect of benzene in the water hexamer is unclear. In particular, it is not obvious how the energy difference between nearly isoenergetic water hexamer conformers changes in the presence of benzene. Thus, we have compared the benzene complexes with four low-lying isoenergetic water hexamers, Ring, Book, Cage, and Prism structures, using ab initio calculations. We also investigated the effects of the presence of benzene on the structures, harmonic vibrational frequencies, and infrared (IR) intensities for the four low-lying energy conformers. There is little change in the structure of the water hexamer upon its interaction with the benzene molecule. Hence the deformation energies are very small. The dominant contribution to the benzene-water cluster interaction mainly comes from the π-H interactions between benzene and a single water molecule. As a result of this π-H interaction, O-Hπ bond length increases and the corresponding stretching vibrational frequencies are redshifted. The IR spectral features of both (H2O)6 and benzene-(H2O)6 are quite similar. From both the energetics and the comparison of calculated and experimental spectra of the benzene-(H2O)6, the water structure in these complexes is found to have the Cage form. In particular, among the four different Cage structures, only one conformer matches the experimental O-H vibrational frequencies.

Three cocrystals and a cocrystal salt of pyrimidin-2-amine and glutaric acid.

PubMed

Odiase, Isaac; Nicholson, Catherine E; Ahmad, Ruksanna; Cooper, Jerry; Yufit, Dmitry S; Cooper, Sharon J

2015-04-01

Four new cocrystals of pyrimidin-2-amine and propane-1,3-dicarboxylic (glutaric) acid were crystallized from three different solvents (acetonitrile, methanol and a 50:50 wt% mixture of methanol and chloroform) and their crystal structures determined. Two of the cocrystals, namely pyrimidin-2-amine-glutaric acid (1/1), C4H5N3·C6H8O4, (I) and (II), are polymorphs. The glutaric acid molecule in (I) has a linear conformation, whereas it is twisted in (II). The pyrimidin-2-amine-glutaric acid (2/1) cocrystal, 2C4H5N3·C6H8O4, (III), contains glutaric acid in its linear form. Cocrystal-salt bis(2-aminopyrimidinium) glutarate-glutaric acid (1/2), 2C4H6N3(+)·C6H6O4(2-)·2C6H8O4, (IV), was crystallized from the same solvent as cocrystal (II), supporting the idea of a cocrystal-salt continuum when both the neutral and ionic forms are present in appreciable concentrations in solution. The diversity of the packing motifs in (I)-(IV) is mainly caused by the conformational flexibility of glutaric acid, while the hydrogen-bond patterns show certain similarities in all four structures.

Thermophysical Properties of Matter - The TPRC Data Series. Volume 6. Specific Heat - Nonmetallic Liquids and Gases

DTIC Science & Technology

1970-01-01

dlcarbide (Cr5C2) Heptachromium tricarbide (CrTCj) Chromium chlorides: CrCl2 CrClj Chromium dichloride (CrC^) Chromium trichloride (CrC...methane (see Propane) Dysprosia (see Dysprosium oxide) Dysprosium Dysprosium trichloride hexahydrate (DyClj-6HjO) Dysprosium oxide (DyjOj...Dysprosium sesquioxide (see Dysprosium oxide) Didysprosium trioxide (see Dysprosium oxide) Erbia (see Erbium oxide) Erbium Erbium trichloride

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheng, Yue; Yang, Meng-Lin; Hu, Huai-Ming, E-mail: ChemHu1@NWU.EDU.CN

Six new coordination polymers, [ZnLCl]{sub n}(1), [ZnL{sub 2}]{sub n}·2nH{sub 2}O (2), [Zn{sub 2}L(o-bdc)(OH)]{sub n}·0.5nH{sub 2}O (3), [Zn{sub 2}L(m-bdc)(OH)]{sub n}·nH{sub 2}O (4), [Zn{sub 2}L{sub 2}(p-bdc) (H{sub 2}O){sub 2}]{sub n}·nH{sub 2}O (5), [Zn{sub 2}L(1,2,4-btc)(H{sub 2}O)]{sub n}(6), (HL=4′-(3-carboxyphenyl)- 3,2′:6′,3″-terpyridine, H{sub 2}(o-bdc)= benzene-1,2-dicarboxylic acid, H{sub 2}(m-bdc)= benzene-1,3-dicarboxylic acid, H{sub 2}(p-bdc)= benzene-1,4-dicarboxylic acid, H{sub 3}(1,2,4-btc)= benzene-1,2,4-tricarboxylic acid) have been synthesized under the hydrothermal conditions. Compound 1 displays a 3-connected 2D network structure with point symbol of {8"2.10}. Compound 2 exhibits 1D infinite loop chain structure. Compound 3 possesses a (3,8)-connected 3D framework composed of tetranuclear units with point symbol of {4"3}{sub 2}{4"6.6"1"8.8"4}. Compound 4 featuresmore » a typical 2D hcb network based on tetranuclear zinc(II) units with point symbol of {4"4.6"2}. Compound 5 presents a classical two-fold penetration sql network with point symbol of {6"3}. Compound 6 can be seen as a (3,3,6)-connected 3D net with point symbol of {4"2.6"4.8"9}{4"2.6}{6"3}. The thermal stability and luminescent properties of compounds 1–6 in the solid state are discussed in detail. - Graphical abstract: Six new Zn(II) coordination polymers based on multicarboxylate and terpyridyl derivative ligands have synthesized under the hydrothermal conditions and the thermal stability and luminescence are discussed. Display Omitted.« less

Aqua complexes of 18—crown-6 with H 3PO 4, H 2TiF 6, and HNO 3: synthesis and vibrational spectra

NASA Astrophysics Data System (ADS)

Chénevert, R.; Rodrigue, A.; Chamberland, D.; Ouellet, J.; Savoie, R.

1985-11-01

Neutral-component complexes of 2:3:1 (acid:water:18-crown-6) stoichiometry have been obtained with H 3PO 4 and H 2TiF 6. These adducts have been studied by infrared and Raman spectroscopy, along with the corresponding (HNO 3-H 1O) 2-18-crown-6 complex, whose synthesis has already been reported. The spectra indicate that the crown ether has a highly regular conformation in these complexes. In those with H 3PO 4 and HNO 3, the binding of the acid molecule to the ether takes place through a H 2O linker, the strength of the XOH⋯OH 2 hydrogen bond being directly related to the p K a of the acid. With HNO 3, the acidic proton appears to be delocalized between the two oxygen atoms, giving a pseudo H 2O + ion whereas in the corresponding deuterocompound the D atom remains associated with the acid.

IUPAC-NIST Solubility Data Series. 95. Alkaline Earth Carbonates in Aqueous Systems. Part 2. Ca

NASA Astrophysics Data System (ADS)

Vanderdeelen, Jan

2012-06-01

The alkaline earth carbonates are an important class of minerals. This article is part of a volume in the IUPAC-NIST Solubility Data Series that compiles and critically evaluates solubility data of the alkaline earth carbonates in water and in simple aqueous electrolyte solutions. Part 1 outlined the procedure adopted in this volume, and presented the beryllium and magnesium carbonates. Part 2, the current paper, compiles and critically evaluates the solubility data of calcium carbonate. The chemical forms included are the anhydrous CaCO3 types calcite, aragonite, and vaterite, the monohydrate monohydrocalcite (CaCO3. H2O), the hexahydrate ikaite (CaCO3.6H2O), and an amorphous form. The data were analyzed with two model variants, and thermodynamic data of each form consistent with each of the models and with the CODATA key values for thermodynamics are presented.

Mechanistic Studies on the Radiolytic Decomposition of Perchlorates on the Martian Surface

NASA Astrophysics Data System (ADS)

Turner, Andrew M.; Abplanalp, Matthew J.; Kaiser, Ralf I.

2016-04-01

Perchlorates—inorganic compounds carrying the perchlorate ion ({{ClO}}4{}-)—were discovered at the north polar landing site of the Phoenix spacecraft and at the southern equatorial landing site of the Curiosity Rover within the Martian soil at levels of 0.4-0.6 wt%. This study explores in laboratory experiments the temperature-dependent decomposition mechanisms of hydrated perchlorates—namely magnesium perchlorate hexahydrate (Mg(ClO4)2·6H2O)—and provides yields of the oxygen-bearing species formed in these processes at Mars-relevant surface temperatures from 165 to 310 K in the presence of galactic cosmic-ray particles (GCRs). Our experiments reveal that the response of the perchlorates to the energetic electrons is dictated by the destruction of the perchlorate ion ({{ClO}}4{}-) and the inherent formation of chlorates ({{ClO}}3{}-) plus atomic oxygen (O). Isotopic substitution experiments reveal that the oxygen is released solely from the perchlorate ion and not from the water of hydration (H2O). As the mass spectrometer detects only molecular oxygen (O2) and no atomic oxygen (O), atomic oxygen recombines to molecular oxygen within the perchlorates, with the overall yield of molecular oxygen increasing as the temperature drops from 260 to 160 K. Absolute destruction rates and formation yields of oxygen are provided for the planetary modeling community.

Syntheses, structures and luminescence for zinc coordination polymers based on a multifunctional 4‧-(3-carboxyphenyl)- 3,2‧:6‧,3″-terpyridine ligand

NASA Astrophysics Data System (ADS)

Cheng, Yue; Yang, Meng-Lin; Hu, Huai-Ming; Xu, Bing; Wang, Xiaofang; Xue, Ganglin

2016-07-01

Six new coordination polymers, [ZnLCl]n(1), [ZnL2]n·2nH2O (2), [Zn2L(o-bdc)(OH)]n·0.5nH2O (3), [Zn2L(m-bdc)(OH)]n·nH2O (4), [Zn2L2(p-bdc) (H2O)2]n·nH2O (5), [Zn2L(1,2,4-btc)(H2O)]n(6), (HL=4‧-(3-carboxyphenyl)- 3,2‧:6‧,3″-terpyridine, H2(o-bdc)= benzene-1,2-dicarboxylic acid, H2(m-bdc)= benzene-1,3-dicarboxylic acid, H2(p-bdc)= benzene-1,4-dicarboxylic acid, H3(1,2,4-btc)= benzene-1,2,4-tricarboxylic acid) have been synthesized under the hydrothermal conditions. Compound 1 displays a 3-connected 2D network structure with point symbol of {82.10}. Compound 2 exhibits 1D infinite loop chain structure. Compound 3 possesses a (3,8)-connected 3D framework composed of tetranuclear units with point symbol of {43}2{46.618.84}. Compound 4 features a typical 2D hcb network based on tetranuclear zinc(II) units with point symbol of {44.62}. Compound 5 presents a classical two-fold penetration sql network with point symbol of {63}. Compound 6 can be seen as a (3,3,6)-connected 3D net with point symbol of {42.64.89}{42.6}{63}. The thermal stability and luminescent properties of compounds 1-6 in the solid state are discussed in detail.

Organic salts formed by 2,4,6-triaminopyrimidine and selected carboxylic acids via a variety of hydrogen bonds: Synthons cooperation, and crystal structures

NASA Astrophysics Data System (ADS)

Xing, Peiqi; Li, Qingyun; Li, Yingying; Wang, Kunpeng; Zhang, Qi; Wang, Lei

2017-05-01

By using solvent evaporation method, 2,4,6-triaminopyrimidine (TAPI) is employed to crystallize with a variety of acids, including 3,5-dihydroxybenzoic acid (HDHBA), 3-nitrophthalic acid (H2NPA), 5-amino-2,4,6-triiodoisophthalic acid (H2ATIPIA), 2,5-dibromoterephthalic acid (H2DBTPA), 1,5-naphthalenedisulfonic acid (H2NDSA), sebacic acid (H2SA), 1,2,4-benzenetricarboxylic acid (H3BTA), and biphenyl-2,2‧,5,5'-tetracarboxylic acid (H4BPTA). In all eight complexes, protons are completely exchanged from O atom of acid to nitrogen of TAPI in 1, 3, 4, and, 5, partly transferred in 2, 6, 7, and 8. The crystal structure of all eight complexes exhibit that classical robust hydrogen bonds X-H⋯X (X = O/N) direct the molecular crystals to bind together in a stacking modes. Classical hydrogen bond Nsbnd H⋯O is participated in forming all eight organic salts, while hydrogen bonding Osbnd H⋯O are found in constructing the diversity structures in salts 1, 2, 3, 4, 6, and 7. The analysis shows that some classical supramolecular synthons, such as I R22(8), V R24(12), and VI S(6), are observed again in the construction of hydrogen-bonding networks. In the formation of layered and reticular structure, strong hydrogen bonds between water molecules and ligands having well-refined hydrogen atoms have been considered. Water molecules play an important role in building supramolecular structures of 1, 2, 3, 4, 7, and 8. Moreover, salts 1-8 are further characterized and analyzed by element analysis, infrared radiation, thermogravimetric analysis, proton nuclear magnetic resonance spectra, and mass spectra.

Co(II) and Ni(II) complexes based on anthraquinone-1,4,5,8-tetracarboxylic acid (H4AQTC): canted antiferromagnetism and slow magnetization relaxation in {[Co2(AQTC)(H2O)6]·6H2O}.

PubMed

Yan, Wei-Hong; Bao, Song-Song; Huang, Jian; Ren, Min; Sheng, Xiao-Li; Cai, Zhong-Sheng; Lu, Chang-Sheng; Meng, Qing-Jin; Zheng, Li-Min

2013-06-21

Three coordination polymers {[Co2(AQTC)(H2O)6]·6H2O}n (1), {[M2(AQTC)(bpym)(H2O)6]·6H2O}n (M = Co(2), Ni(3)) have been synthesized and structurally characterized, where H4AQTC is anthraquinone-1,4,5,8-tetracarboxylic acid and bpym is 2,2'-bipyrimidine. Complex 1 features a 3-D structure, where layers of Co2(AQTC) are cross-linked by Co-H2O chains. Complexes 2 and 3 are isostructural and display 1-D chain structures. The chains are connected through hydrogen-bonding interactions to form 3-D supramolecular structures. Magnetic properties of these complexes are investigated. Compound 1 shows canted antiferromagnetism and slow relaxation below 4.0 K. For complexes 2 and 3, dominant antiferromagnetic interactions are observed. The luminescent properties of the three complexes are investigated as well.

Growth and characterization of ammonium nickel-cobalt sulfate Tutton's salt for UV light applications

NASA Astrophysics Data System (ADS)

Ghosh, Santunu; Oliveira, Michelle; Pacheco, Tiago S.; Perpétuo, Genivaldo J.; Franco, Carlos J.

2018-04-01

We have obtained a set of sample crystals of the family of Tutton's salt comprise in the isomorphic series with general chemical formula (NH4)2NixCo(1-x) (SO4)2·6H2O, by employing growth from solutions by slow evaporation technique. The samples crystals were characterized by ICP-AES, X-ray powder diffraction analysis, thermogravimetric analysis, UV-Vis-NIR, Raman and FTIR spectroscopy. This type of material has been studied because of its physical and chemical properties not yet understood and they have potential technological applications. Chemical analysis of the samples by ICP-AES method allowed us to investigate the efficiency of the method of growth used. Thermogravimetric analysis provides the information about the thermal stability of the obtained crystals for high temperature applications, and powder X-ray diffraction analysis at ambient and high temperature reveals the structural quality and structural change of the samples respectively. We have used Raman spectroscopy in the range 100-4000 cm-1 and FTIR spectroscopy in the range 400-4000 cm-1 to understand the internal vibrational mode of the octahedral complexes [Ni(H2O)6]2+ and [Co(H2O)6]2+, SO42- and NH4+ tetrahedra. The transmittance of our mixed ammonium nickel cobalt sulfate hexahydrate (ACNSH) crystals is 75% in the UV region, which indicates that they are ideal to use in UV light filters and UV sensors.

Crystal structures of two solvates of (18-crown-6)potassium acetate.

PubMed

Liebing, Phil; Zaeni, Ahmad; Olbrich, Falk; Edelmann, Frank T

2016-12-01

The crystal and mol-ecular strutures of two solvated forms of [K(18 c 6)]OAc (18 c 6 = 18-crown-6 = 1,4,7,10,13,16-hexa-oxa-cyclo-octa-decane and OAc = acetate) were determined by single-crystal X-ray diffraction, namely (acetato-κ 2 O , O ')(1,4,7,10,13,16-hexa-oxa-cyclo-octa-decane-κ 6 O )potassium dihydrate, [K(CH 3 COO)(C 12 H 24 O 6 )]·2H 2 O ( 1 ) and (acetato-κ 2 O , O ')aqua-(1,4,7,10,13,16-hexa-oxa-cyclo-octa-decane-κ 6 O )potassium acetic acid monosolvate [K(CH 3 COO)(C 12 H 24 O 6 )(H 2 O)]·CH 3 COOH ( 2 ). In both compounds, the acetate anion is bonded to the potassium ion in a chelating fashion and the metal atom is consequently slightly displaced from the O 6 plane of the crown ether. In the crystals, O-H⋯O hydrogen bonds lead to a polymeric ladder structure in the dihydrate 1 , while the acetic acid hydrate 2 features inversion dimers.

Synthesis and characterization of struvite nano particles

NASA Astrophysics Data System (ADS)

Rathod, K. R.; Jogiya, B. V.; Chauhan, C. K.; Joshi, M. J.

2015-06-01

Struvite, Ammonium Magnesium Phosphate Hexahydrate [(AMPH) - (NH4)MgPO4.6(H2O)], is one of the fascinating inorganic phosphate minerals. Struvite is one of the components of the urinary stones. Struvite occurs as crystallites in urine and grows as a type of kidney stone. In this study, struvite nano particles were synthesized by wet chemical technique. The aqueous solutions containing dissolved Mg(CH3COO)2.4H2O and (NH4)H2PO4 mixed at the Mg/P molar ratio of 1.00. The synthesized struvite nano particles were characterized by XRD, FT-IR, Thermal Analysis and TEM. From XRD, crystal structure of the nano particle was found to be orthorhombic and crystalline size was found to be within 11 to 26 nm. The FT-IR spectrum for the struvite nano particles confirmed the presence of a water molecule and metal-oxygen stretching vibration, O-H stretching and bending, N-H bending and stretching, P-O bending and stretching vibrations. The Thermal Analysis was carried out from room temperature to 900°C. From TEM analysis, particle size was 23 to 30 nm. All the results were compared with bulk struvite.

Precipitation diagrams and solubility of uric acid dihydrate

NASA Astrophysics Data System (ADS)

Babić-Ivančić, V.; Füredi-Milhofer, H.; Brown, W. E.; Gregory, T. M.

1987-07-01

The solubility of uric acid dihydrate (UA·2H 2O) and the precipitation of UA·2H 2O and anhydrous uric acid (UA) from solutions containing sodium hydroxide and hydrochloric acid have been investigated. For the solubility studies, crystals of pure UA·2H 2O were prepared and equilibrated with water and with solutions of HCl or NaOH for 60 min or 20 h, respectively. The equilibrium pH (pH = 2-6.25) and uric acid concentration were determined. For the precipitation experiments, commercial UA was dissolved in NaOH in a 1:1.1 molar ratio and UA·2H 2O and/or UA were precipitated with hydrochloric acid. The precipitates and/or supernatants were examined 24 h after sample preparation. The results are represented in the form of tables, precipitation diagrams and "chemical potential" diagrams. Solubility measurements with 60 min equilibration times yielded the solubility products of UA·2H 2O, K sp(298 K) = (0.926 ± 0.025) × 10 -9mol2dm-6 and K sp(310 K) = (2.25 ± 0.05) × 10 -9mol2dm-6 and the first dissociation constants of uric acid, K 1(298 K) = (2.45 ± 0.07) × 10 -6moldm-3 and K 1(310 K) = (3.63 ± 0.08) × 10 -6moldm-3. Precipitation diagrams show that under the given experimental conditions, at 298 K, UA·2H 2O is stable for 24 h while at 310 K this was true only for precipitates formed from solutions of high supersaturations. At lower supersaturations, mixtures of UA·2H 2O and UA formed. Consequently, while the Ksp value determined from precipitation data obtained at 298 K (K sp = 1.04 × 10 -9mol2dm-6) was consistent with the respective solubility product, the 310 K precipitation boundary yielded an ion activity product, AP, the value of which fulfills the conditions Ksp(UA) < AP < Ksp (UA·2H 2O). Similar ion activity products were obtained from solubility measurements in pure water at 20 h equilibration time.

Optimized LWIR enhancement of nanosecond and femtosecond LIBS uranium emission

NASA Astrophysics Data System (ADS)

Akpovo, Codjo A.; Ford, Alan; Johnson, Lewis

2016-05-01

A carbon dioxide (CO2) transverse electrical breakdown in atmosphere (TEA), pulsed laser was used to enhance the laser-induced breakdown spectroscopy (LIBS) spectral signatures of uranium under nanosecond (ns) and femtosecond (fs) ablation. The peak areas of both ionic and neutral species increased by one order of magnitude for ns-ablation and two orders of magnitude for fs-ablation over LIBS when the CO2 TEA laser was used with samples of dried solutions of uranyl nitrate hexahydrate (UO2(NO3)2·6H2O) on silicon wafers. Electron temperature and density measurements show that the spectral emission improvement from using the TEA laser comes from plasma reheating.

Anhydrous 1:1 proton-transfer compounds of isonipecotamide with picric acid and 3,5-dinitrosalicylic acid: 4-carbamoylpiperidinium 2,4,6-trinitrophenolate and two polymorphs of 4-carbamoylpiperidinium 2-carboxy-4,6-dinitrophenolate.

PubMed

Smith, Graham; Wermuth, Urs D

2010-12-01

The structures of the anhydrous 1:1 proton-transfer compounds of isonipecotamide (piperidine-4-carboxamide) with picric acid and 3,5-dinitrosalicylic acid, namely 4-carbamoylpiperidinium 2,4,6-trinitrophenolate, C(6)H(13)N(2)O(+)·C(6)H(2)N(3)O(7)(-), (I), and 4-carbamoylpiperidinium 2-carboxy-4,6-dinitrophenolate [two forms of which were found, the monoclinic α-polymorph, (II), and the triclinic β-polymorph, (III)], C(6)H(13)N(2)O(+)·C(7)H(3)N(2)O(7)(-), have been determined at 200 K. All three compounds form hydrogen-bonded structures, viz. one-dimensional in (II), two-dimensional in (I) and three-dimensional in (III). In (I), the cations form centrosymmetric cyclic head-to-tail hydrogen-bonded homodimers [graph set R(2)(2)(14)] through lateral duplex piperidinium-amide N-H...O interactions. These dimers are extended into a two-dimensional network structure through further interactions with phenolate and nitro O-atom acceptors, including a direct symmetric piperidinium-phenol/nitro N-H...O,O cation-anion association [graph set R(1)(2)(6)]. The monoclinic polymorph, (II), has a similar R(1)(2)(6) cation-anion hydrogen-bonding interaction to (I) but with an additional conjoint symmetrical R(1)(2)(4) interaction as well as head-to-tail piperidinium-amide N-H...O,O hydrogen bonds and amide-carboxyl N-H...O hydrogen bonds, giving a network structure which includes large R(4)(3)(20) rings. The hydrogen bonding in the triclinic polymorph, (III), is markedly different from that of monoclinic (II). The asymmetric unit contains two independent cation-anion pairs which associate through cyclic piperidinium-carboxyl N-H...O,O' interactions [graph set R(1)(2)(4)]. The cations also show the zigzag head-to-tail piperidinium-amide N-H...O hydrogen-bonded chain substructures found in (II), but in addition feature amide-nitro and amide-phenolate N-H...O associations. As well, there is a centrosymmetric double-amide N-H...O(carboxyl) bridged bis(cation-anion) ring system [graph set R(4)(2)(8)] in the three-dimensional framework. The structures reported here demonstrate the utility of the isonipecotamide cation as a synthon with previously unrecognized potential for structure assembly applications. Furthermore, the structures of the two polymorphic 3,5-dinitrosalicylic acid salts show an unusual dissimilarity in hydrogen-bonding characteristics, considering that both were obtained from identical solvent systems.

Hydrogen bonded 1D-3D supramolecular structures from Benzylamine and organic acidic components

NASA Astrophysics Data System (ADS)

Gao, Xingjun; Li, XiaoLiang; Jin, Shouwen; Hu, Kaikai; Guo, Jianzhong; Guo, Ming; Xu, Weiqiang; Wang, Daqi

2018-03-01

Cocrystallization of the commonly available organic amine, benzylamine, with a series of organic acids afforded a total of seven organic salts with the compositions: (benzylamine)2: (p-nitrophenol)2: (H2O) (1) [(HL)2+⋯(npl-)2⋯(H2O), npl- = p-nitrophenolate], (benzylamine): (4-tert-butylbenzoic acid) (2) [(HL+)⋯(tba-), tba- = 4-tert-butylbenzoate], (benzylamine): (3,4-dichlorobenzoic acid) (3) [(HL+)⋯dcba-), dcba- = 3,4-dichlorobenzoate], (benzylamine): (2,5-dihydroxybenzoic acid) (4) [(HL+)⋯(dhba-), dhba- = 2,5-dihydroxybenzoate], (benzylamine): (2-bromo-but-2-enedioic acid) (5) [(HL+)⋯(Hbba-), Hbba- = 2-bromo-hydrogenbut-2-enedioate], (benzylamine): (2,6-pyridinedicarboxylic acid) (6) [(HL+)⋯(Hpdc-), Hpdc- = 2,6-pyridine hydrogendicarboxylate], and (benzylamine)2: (3-nitrophthalic acid): 2(H2O) (7) [(HL+)2⋯(npa2-)⋯(H2O)2, npa2- = 3-nitrophthalate]. The seven salts have been characterised by X-ray diffraction analysis, IR, and elemental analysis, and the melting points of all the salts were also reported. And their structural and supramolecular aspects are fully analyzed. The results reveal that among the seven investigated crystals the NH2 in the benzylamine are protonated when the organic acids are deprotonated, and the crystal packing is interpreted in terms of the strong charge-assisted Nsbnd H⋯O hydrogen bond between the NH3+ and deprotonated acidic groups. Except the Nsbnd H⋯O hydrogen bond, the Osbnd H⋯O hydrogen bonds (charge assisted or neutral) were also found at the salts 1, 4, 5, 6, and 7. Further analysis of the crystal packing of the salts indicated that a different family of additional CHsbnd O/CH2sbnd O, CH-π/CH2-π, Cπ-Cπ, Osbnd O, O-Cπ, O-π, and Cl-π associations also contribute to the stabilization and expansion of the total high-dimensional framework structures. For the coexistence of the various weak nonbonding interactions, these structures adopted a variety of supramolecular synthons of R12(4), R12(5), R21(5), R22(6), R22(10), R32(6), R32(9), R33(9), R42(8), R42(9), R43(10), R44(12), R44(20), R52(9), and R64(12).

In Situ Detection of Chlorine Dioxide (C1O2) in the Radiolysis of Perchlorates and Implications for the Stability of Organics on Mars

NASA Astrophysics Data System (ADS)

Góbi, Sándor; Bergantini, Alexandre; Kaiser, Ralf I.

2016-12-01

Magnesium perchlorate hexahydrate (Mg(ClO4)2 · 6H2O) samples were exposed to energetic electrons to investigate the products of the decomposition of perchlorates in the Martian soil and to infer their role in the degradation of organics on Mars. The samples were monitored online and in situ via infrared spectroscopy as well as electron impact (EI-QMS) and reflectron time-of-flight mass spectrometry coupled with single photon ionization (PI-ReTOF-MS). Our study reveals that besides chlorates ({{{ClO}}3}-) and molecular oxygen (O2), the chlorine dioxide radical (ClO2) was observed online and in situ for the first time as a radiolysis product of solid perchlorates. Chlorine dioxide, which is used on Earth as a strong oxidizing agent in water disinfection and bleaching, represents a proficient oxidizer—potentially more powerful than molecular oxygen—to explain the lack of abundant organics in the Martian soil.

MgO NPs synthesis, capping and enhanced free radical effect on the bacteria and its cell morphology

NASA Astrophysics Data System (ADS)

Kushwaha, Amisha; Bagchi, T.

2018-05-01

Magnesium Oxide Nanoparticles (MgO NPs) commonly known as Magnesia is a white powder, hygroscopic material. MgO NPs were synthesized through four methods Co-precipitation method (Co-PM), Solution combustion (S-CoM) and Sol-gel method with starch (So-GSM) and CTAB (So-GCM), classified as template dependent and template independent method using magnesium nitrate hexahydrate (Mg(NO3).6H2O) as the precursor and comparative analysis was done through DLS. The order of hydrodynamic diameters of four different synthesis method of MgO NPs is Co-PM LA-MgO NPs> MgO NPs responding.

Three-dimensional supramolecular architecture in imidazolium hydrogen 2,3,5,6-tetrafluoroterephthalate.

PubMed

Yu, Li-Li; Cheng, Mei-Ling; Liu, Qi; Zhang, Zhi-Hui; Chen, Qun

2010-04-01

The asymmetric unit of the title salt formed between 2,3,5,6-tetrafluoroterephthalic acid (H(2)tfbdc) and imidazolium (ImH), C(3)H(5)N(2)(+).C(8)HF(4)O(4)(-), contains one Htfbdc(-) anion and one ImH(2)(+) cation, joined by a classical N-H...O hydrogen bond. The acid and base subunits are further linked by N-H...O and O-H...O hydrogen bonds into infinite two-dimensional layers with R(6)(5)(32) hydrogen-bond motifs. The resulting (4,4) network layers interpenetrate to produce an interlocked three-dimensional structure. The final three-dimensional supramolecular architecture is further stabilized by the linkages of two C-H...O interactions.

Syntheses and structure characterization of ten acid-base hybrid crystals based on N-containing aromatic brønsted bases and mineral acids

NASA Astrophysics Data System (ADS)

Lin, Zhihao; Jin, Shouwen; Li, Xiaoliang; Xiao, Xiao; Hu, Kaikai; Guo, Ming; Chi, Xinchen; Liu, Hui; Wang, Daqi

2017-10-01

Cocrystallization of the aromatic brønsted bases with a series of mineral acids gave a total of ten hybrid salts with the compositions: (2-methylquinoline)2: (hydrochloride acid): 3H2O [(HL1)+. (L1)·· (Cl-) · (H2O)3] (1), (6-bromobenzo[d]thiazol-2-amine): (hydrochloride acid) [(HL2)+. (Cl-)] (2), (6-bromobenzo[d]thiazol-2-amine): (nitric acid) [(HL2)+. (NO3-)] (3), (6-bromobenzo[d]thiazol-2-amine): (sulfuric acid) [(HL2)+ · (HSO4)-] (4), (6-bromobenzo[d]thiazol-2-amine): (phosphoric acid) [(HL2)+ · (H2PO4)-] (5), (5,7-dimethyl-1,8-naphthyridine-2-amine): (hydrochloride acid): 3H2O [(HL3)+ · (Cl-) (H2O)3] (6), (5,7-dimethyl-1,8-naphthyridine-2-amine): (hydrobromic acid): CH3OH [(HL3)+ · (Br)- · CH3OH] (7), (5,7-dimethyl-1,8-naphthyridine-2-amine): (sulfuric acid): H2O [(HL3)+ · (HSO4)- · H2O] (8), (2-aminophenol): (phosphoric acid) [(HL4)+ · (H2PO4)-] (9), and (2-amino-4-chlorophenol): (phosphoric acid) [(HL5)+ · (H2PO4)-] (10). The ten salts have been characterized by X-ray diffraction analysis, IR, and elemental analysis, and the melting points of all the salts were also reported. And their structural and supramolecular aspects are fully analyzed. The result reveals that among the ten investigated crystals the ring N of the heterocycle or the NH2 in the aminophenol are protonated when the acids are deprotonated, and the crystal packing is interpreted in terms of the strong charge-assisted classical hydrogen bonds between the NH+/NH3+ and deprotonated acidic groups. Further analysis of the crystal packing of the salts indicated that a different family of additional CHsbnd O, CHsbnd Cl, CH3sbnd N, CH3sbnd O, CHsbnd Br, CH3sbnd Br, Brsbnd Cl, Clsbnd S, Osbnd S, Osbnd O, Brsbnd S, Hsbnd H, and π-π associations contribute to the stabilization and expansion of the total high-dimensional frameworks. For the coexistence of the various weak nonbonding interactions these structures adopted homo or hetero supramolecular synthons or both. Some classical supramolecular synthons, such as R22(8), R42(8), R43(10) and R44(12), usually observed in the organic solids, were again shown to be involved in constructing most of these H-bonding networks.

Effect of the temperature on structural and optical properties of zinc oxide nanoparticles.

PubMed

Hadia, N M A; García-Granda, Santiago; García, José R

2014-07-01

Zinc nitrate hexahydrate, Zn(NO3)2 x 6H2O was used as a precursor with urea NH2CONH2 to prepare hydrozincite Zn5(CO3)2(OH)6 powder using hydrothermal method for 8 h at 90 degrees C. Zinc oxide (ZnO) nanoparticles (NPs) were prepared by thermal annealing of hydrozincite powder at different annealing temperatures, i.e., 350, 550 750 and 950 degrees C in air for 2 h. The resulting materials were characterized by X-ray diffraction, scanning electron microscopy (SEM) and thermal gravimetric analysis (TGA). The optical properties of the products were characterized by Fourier transform infrared spectroscopy (FT-IR), UV-Vis spectroscopy and photoluminescence (PL) spectra. It was found that the particle size increased from - 33 to 250 nm with increasing in the annealing temperatures. FTIR results showed that the standard peaks of zinc oxide were presented at 428.17 and 532.32 cm(-1). Thermal analysis study showed that the primary weight loss starts at - 93 degrees C is due to solvent evaporation. The secondary weight loss, observed at - 378 degrees C, is due to phase transition from hydrated zinc oxide to zinc oxide. The band gaps of the products were in the range - 3.26-3.30 eV. The PL spectrum showed that the as-synthesized ZnO nanoparticles had UV (381 nm) and green (537 nm) emissions.

The decolorization and mineralization of acid orange 6 azo dye in aqueous solution by advanced oxidation processes: a comparative study.

PubMed

Hsing, Hao-Jan; Chiang, Pen-Chi; Chang, E-E; Chen, Mei-Yin

2007-03-06

The comparison of different advanced oxidation processes (AOPs), i.e. ultraviolet (UV)/TiO(2), O(3), O(3)/UV, O(3)/UV/TiO(2), Fenton and electrocoagulation (EC), is of interest to determine the best removal performance for the destruction of the target compound in an Acid Orange 6 (AO6) solution, exploring the most efficient experimental conditions as well; on the other hand, the results may provide baseline information of the combination of different AOPs in treating industrial wastewater. The following conclusions can be drawn: (1) in the effects of individual and combined ozonation and photocatalytic UV irradiation, both O(3)/UV and O(3)/UV/TiO(2) processes exhibit remarkable TOC removal capability that can achieve a 65% removal efficiency at pH 7 and O(3) dose=45mg/L; (2) the optimum pH and ratio of [H(2)O(2)]/[Fe(2+)] found for the Fenton process, are pH 4 and [H(2)O(2)]/[Fe(2+)]=6.58. The optimum [H(2)O(2)] and [Fe(2+)] under the same HF value are 58.82 and 8.93mM, respectively; (3) the optimum applied voltage found in the EC experiment is 80V, and the initial pH will affect the AO6 and TOC removal rates in that acidic conditions may be favorable for a higher removal rate; (4) the AO6 decolorization rate ranking was obtained in the order of O(3)

Three pharmaceuticals cocrystals of adefovir: Syntheses, structures and dissolution study

NASA Astrophysics Data System (ADS)

Zhang, Xiaoming; Sun, Fuxing; Zhang, Tingting; Jia, Jiangtao; Su, Hongmin; Wang, Chenhui; Zhu, Guangshan

2015-11-01

We report here three novel cocrystals, which are composed of adefovir as the API (Active Pharmaceutical Ingredient) with p-aminobenzoic acid (1, 2C8H12N5O4P·C7H6NO2·3H2O), 3,5-dihydroxybenzoic acid (2, C8H12N5O4P·C7H6O4·H2O) and 2,6-pyridinedicarboxlic acid (3, C8H12N5O4P·C7H5NO4) as CCFs (cocrystal formers) respectively by crystal engineering strategy. Their structures were characterized by single crystal X-ray diffraction, powder X-ray diffraction (PXRD) analysis, thermogravimetric analyses (TGA), elemental analysis (EA) and infrared spectral analysis (IR). The analysis of single crystal X-ray diffraction demonstrate that cocrystal 1 and 2 form a strong hydrogen-bonded assembly through the phosphoric acids of API with water in the lattice and carboxylic acids of CCF respectively. Cocrystal 3 is formed in which the phosphoric acid groups of API are also held by the carboxylic acid groups of CCF. The PXRD results indicate their high purity of as-synthesized samples. The TGA, EA, IR and dissolution study of API and the cocrystals were also measured and discussed.

Elucidating the Higher Stability of Vanadium (V) Cations in Mixed Acid Based Redox Flow Battery Electrolytes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vijayakumar, M.; Wang, Wei; Nie, Zimin

2013-11-01

The Vanadium (V) cation structures in mixed acid based electrolyte solution were analysed by density functional theory (DFT) based computational modelling and 51V and 35Cl Nuclear Magnetic Resonance (NMR) spectroscopy. The Vanadium (V) cation exists as di-nuclear [V2O3Cl2.6H2O]2+ compound at higher vanadium concentrations (≥1.75M). In particular, at high temperatures (>295K) this di-nuclear compound undergoes ligand exchange process with nearby solvent chlorine molecule and forms chlorine bonded [V2O3Cl2.6H2O]2+ compound. This chlorine bonded [V2O3Cl2.6H2O]2+ compound might be resistant to the de-protonation reaction which is the initial step in the precipitation reaction in Vanadium based electrolyte solutions. The combined theoretical and experimental approachmore » reveals that formation of chlorine bonded [V2O3Cl2.6H2O]2+ compound might be central to the observed higher thermal stability of mixed acid based Vanadium (V) electrolyte solutions.« less

A series of divalent metal coordination polymers based on isomeric tetracarboxylic acids: synthesis, structures and magnetic properties.

PubMed

Han, Min-Le; Duan, Ya-Ping; Li, Dong-Sheng; Xu, Guo-Wang; Wu, Ya-Pan; Zhao, Jun

2014-12-14

Five new coordination polymers, namely, [Mn(2,2′-bipy)(H2O)2(H2L1)]n (1), {[Co(btb)(H2O)2(H2L1)]·0.5H2O}n (2), [Co(bib)(H2O)2(H2L1)]n (3), [Ni2(bpm)(H2O)3(L2)]n (4), and {[Co2(H2O)3(OH)(HL2)]·H2O}n (5), (H4L1 = 1,1′:2′,1′′-terphenyl-4,4′,4′′,5′-tetracarboxylic acid, H4L2 = 1,1′:2′,1′′-terphenyl-3,3′′,4′,5′-tetracarboxylic acid, 2,2′-bipy = 2,2′-bipyridine, btb = 1,4-bis(1,2,4-triazol-1-yl)butane, bib = 1,4-bis(imidazol-1-yl)butane, bpm = bis(4-pyridyl)amine), have been obtained under hydrothermal conditions. Complex 1 exhibits a 3D supramolecular framework based on 1D chains. Both complexes 2 and 3 are 3D supramolecular frameworks constructed from 1D zig-zag chains. Complex 4 features a 3D tetra-nodal (3,4,4,5)-connected architecture containing 1D μ-COO bridged chains with (5(2)·6(2)·7.9)(5(2)·6(4)·7(3)·8)2(5(2)·6)2(6(3)·7(2)·9) topology. Complex 5 shows a 3D penta-nodal (3,4,4,6,6)-connected net containing 1D μ-OH/μ-COO bridged chains and mononuclear Co(II) nodes with a (4(2)·6(3)·8)(4(3))2(4(4)·6(2))2(4(4)·6(6)·8(5))2(4(4)·6(7)·8(4)) topology. Variable-temperature magnetic susceptibility measurements reveal that complexes 2 and 3 show antiferromagnetic interactions between the adjacent Co(II) ions, whereas 4 is a ferromagnetic system.

Hydrothermal syntheses, crystal structures and luminescence properties of zinc(II) and cadmium(II) coordination polymers based on bifunctional 3,2 Prime :6 Prime ,3 Prime Prime -terpyridine-4 Prime -carboxylic acid

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Na; Guo, Hui-Lin; Hu, Huai-Ming, E-mail: ChemHu1@NWU.EDU.CN

2013-02-15

Five new coordination polymers, [Zn{sub 2}(ctpy){sub 2}Cl{sub 2}]{sub n} (1), [Zn{sub 2}(ctpy){sub 2}(ox)(H{sub 2}O){sub 2}]{sub n} (2), [Zn{sub 2}(ctpy)(3-btc)(H{sub 2}O)]{sub n}{center_dot}0.5nH{sub 2}O (3), [Cd(ctpy){sub 2}(H{sub 2}O)]{sub n} (4), [Cd{sub 4}(ctpy){sub 2}(2-btc){sub 2}(H{sub 2}O){sub 2}]{sub n}{center_dot}2nH{sub 2}O (5), (Hctpy=3,2 Prime :6 Prime ,3 Prime Prime -terpyridine-4 Prime -carboxylic acid, H{sub 2}ox=oxalic acid, H{sub 3}(3-btc)=1,3,5-benzenetricarboxylic acid, H{sub 3}(2-btc)=1,2,4-benzenetricarboxylic acid) have been synthesized under hydrothermal conditions and characterized by elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction. Compounds 1-2 are a one-dimensional chain with weak interactions to form 3D supramolecular structures. Compound 3 is a 4-nodal 3D topology framework comprised of binuclear zincmore » units and (ctpy){sup -} anions. Compound 4 shows two dimensional net. Compound 5 is a (4,5,6)-connected framework with {l_brace}4{sup 4}{center_dot}6{sup 2}{r_brace}{l_brace}4{sup 6}{center_dot}6{sup 4}{r_brace}{sub 2}{l_brace}4{sup 9}{center_dot}6{sup 6}{r_brace} topology. In addition, the thermal stabilities and photoluminescence properties of 1-5 were also studied in the solid state. - Graphical abstract: Five new Zn/Cd compounds with 3,2 Prime :6 Prime ,3 Prime Prime -terpyridine-4 Prime -carboxylic acid were prepared. The photoluminescence and thermal stabilities properties of 1-5 were investigated in the solid state. Highlights: Black-Right-Pointing-Pointer Five new zinc/cadmium metal-organic frameworks have been hydrothermal synthesized. Black-Right-Pointing-Pointer The structural variation is attributed to the diverse metal ions and auxiliary ligand. Black-Right-Pointing-Pointer Compounds 1-5 exhibit 1D ring chain, 2D layer and 3D open-framework, respectively. Black-Right-Pointing-Pointer These compounds exhibit strong solid state luminescence emission at room temperature.« less

Structural insights into two inorganic-organic hybrids based on chiral amino acids and polyoxomolybdates

NASA Astrophysics Data System (ADS)

Arefian, Mina; Mirzaei, Masoud; Eshtiagh-Hosseini, Hossein

2018-03-01

A new chiral inorganic-organic hybrid with the formula (L-His)2(H7CoMo6O24)·6H2O (1), based on natural amino acid and Anderson type polyoxomolybdate was synthesized through mild condition. The chiral L-histidine molecules induced chirality to the whole structure through various types of strong and unconventional hydrogen bond (HB) interactions (CH⋯O, NH⋯O and CH···π interactions), as well as bifurcated hydrogen bonds (BHBs) between L-histidine amino acid, hexamer water cluster molecules, and H7CoMo6O24·xH2O. Following, important non-covalent CH⋯O interactions is investigated in another chiral inorganic-organic hybrid structure, (L-Pro)3(PMo12O40).4.5H2O (2), in detail. The CH⋯O hydrogen bonds lead to a chiral network similar to the DNA strands affording a promising candidate to bio-inorganic studies.

IUPAC-NIST Solubility Data Series. 95. Alkaline Earth Carbonates in Aqueous Systems. Part 2. Ca

DOE Office of Scientific and Technical Information (OSTI.GOV)

De Visscher, Alex; Vanderdeelen, Jan; Department of Applied Analytical and Physical Chemistry, Faculty of Bioscience Engineering, Ghent University, B-9000 Ghent

The alkaline earth carbonates are an important class of minerals. This article is part of a volume in the IUPAC-NIST Solubility Data Series that compiles and critically evaluates solubility data of the alkaline earth carbonates in water and in simple aqueous electrolyte solutions. Part 1 outlined the procedure adopted in this volume, and presented the beryllium and magnesium carbonates. Part 2, the current paper, compiles and critically evaluates the solubility data of calcium carbonate. The chemical forms included are the anhydrous CaCO{sub 3} types calcite, aragonite, and vaterite, the monohydrate monohydrocalcite (CaCO{sub 3}{center_dot} H{sub 2}O), the hexahydrate ikaite (CaCO{sub 3}{center_dot}6H{submore » 2}O), and an amorphous form. The data were analyzed with two model variants, and thermodynamic data of each form consistent with each of the models and with the CODATA key values for thermodynamics are presented.« less

2,4,6-Tri-amino-1,3,5-triazin-1-ium 3-(prop-2-eno-yloxy)propano-ate acrylic acid monosolvate monohydrate.

PubMed

Sangeetha, V; Kanagathara, N; Chakkaravarthi, G; Marchewka, M K; Anbalagan, G

2013-05-01

The asymmetric unit of the title salt, C3H7N6 (+)·C6H7O4 (-)·C3H4O2·H2O, contains a 2,4,6-tri-amino-1,3,5-triazin-1-ium cation, a 3-(prop-2-eno-yloxy)propano-ate anion and acrylic acid and water solvent mol-ecules in a 1:1:1:1 ratio and with each species in a general position. In the crystal, the components are linked into a supra-molecular layer in the bc plane via a combination of O-H⋯O, N-H⋯N and N-H⋯O hydrogen bonding. The crystal studied was a non-merohedral twin, the minor component contribution being approximately 26%.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aadila, A., E-mail: aadilaazizali@gmail.com; Asib, N. A. M.; Afaah, A. N.

In this work, solution-immersion method was used to grow ZnO rods on PMMA-coated substrate. For this purpose, 0.15 M of zinc nitrate hexahydrate (Zn(NO{sub 3}){sub 2}.6H{sub 2}O) and hexamethylenetetramine (C{sub 6}H{sub 12}N{sub 4}) were used to growth of ZnO films at different annealing temperatures (room temperature, 80, 100, 120 and 140 °C). The morphology of the films was investigated by Scanning Electron Microscope (SEM) and optical properties were studied by Ultraviolet (UV-Vis) Spectroscopy. SEM analysis showed ubiquitous growth of ZnO rods that became better aligned and more closely-packed as the annealing temperature increased. As the annealing temperature exceeds 100 °C,more » the rods tend to merge to adjacent particles and the UV absorption decreased for the sample at higher temperatures (120 °C and 140 °C). Good absorption and better orientation of ZnO was obtained for the sample annealed at 100 °C due to the film possess better distribution and these improved orientation of particles caused the light to be effectively scattered on the sample. Both surface morphology and UV was significantly affected by the change in annealing temperatures thus thermal effect played a dominant role in shaping and improving the orientation of ZnO rods on PMMA-coated and its UV absorption.« less

A series of coordination polymers constructed from R-isophthalic acid (R=-SO3H, -NO2, and -OH) and N-donor ligands: Syntheses, structures and fluorescence properties

NASA Astrophysics Data System (ADS)

Zhou, Yong-Hong; Zhou, Xu-Wan; Zhou, Su-Rong; Tian, Yu-Peng; Wu, Jie-Ying

2017-01-01

Six novel Zn(II), Cd(II), and Cu(II) mixed-ligand coordination complexes, namely, [Zn2Na(sip)2(bpp)3(Hbpp)(H2O)2]·8H2O (1), [Cd3(sip)2(nbi)6(H2O)2]·7H2O (2), [Zn(sip)(nbi)2(H2O)]·Hnbi·3H2O (3), [Cd(hip)(nbi)2(H2O)]·nbi·5H2O (4), [Cd2(nip)2(nbi)2(H2O)2]·DMF (5), and [Cu(nip)(nbi)(H2O)2]·H2O (6) (H3sip=5-sulfoisophthalic acid, H2hip=5-hydroxylisophthalic acid, H2nip=5-nitroisophthalic acid, bpp=1,3-bis(4-pyridyl)propane, and nbi=6-nitrobenzimidazole) have been synthesized hydrothermally by the self-assembly of R-isophthalic acid (R=-SO3H, -NO2, and -OH) and N-donor ligands. Single crystal X-ray analyses reveal that two Zn(II) ions and one Na(I) ion of complex 1 are linked through O atoms to generate a 1D linear chain. Then the 2D supramolecular architectures are constructed via intermolecular interactions. In complex 2, the Cd1 ions are connected by bridging carboxyl groups from sip3- anions to form 1D double chain, which are further connected by Cd2 ions to afford 2D layer structure. The adjacent 2D layers are further linked via hydrogen-bonding interactions to give 3D supramolecular network. Compounds 3-5 show 1D chain structures, which are assembled into 2D or 3D supramolecular frameworks via weak interactions. In compound 6, the Cu(II) ions are bridged by the nip2- ligands to form 48-membered ring, which is assembled into 1Dchain via the π-π stacking interaction. In addition, the thermal stabilities and fluorescence properties of these compounds have also been studied.

New metal-organic frameworks of [M(C6H5O7)(C6H6O7)(C6H7O7)(H2O)] . H2O (M=La, Ce) and [Ce2(C2O4)(C6H6O7)2] . 4H2O

NASA Astrophysics Data System (ADS)

Weng, Sheng-Feng; Wang, Yun-Hsin; Lee, Chi-Shen

2012-04-01

Two novel materials, [M(C6H5O7)(C6H6O7)(C6H7O7)(H2O)] . H2O (M=La(1a), Ce(1b)) and [Ce2(C2O4)(C6H6O7)2] . 4H2O (2), with a metal-organic framework (MOF) were prepared with hydrothermal reactions and characterized with photoluminescence, magnetic susceptibility, thermogravimetric analysis and X-ray powder diffraction in situ. The crystal structures were determined by single-crystal X-ray diffraction. Compound 1 crystallized in triclinic space group P1¯ (No. 2); compound 2 crystallized in monoclinic space group P21/c (No. 14). The structure of 1 is built from a 1D MOF, composed of deprotonated citric ligands of three kinds. Compound 2 contains a 2D MOF structure consisting of citrate and oxalate ligands; the oxalate ligand arose from the decomposition in situ of citric acid in the presence of CuII ions. Photoluminescence spectra of compounds 1b and 2 revealed transitions between the 5d1 excited state and two levels of the 4f1 ground state (2F5/2 and 2F7/2). Compounds 1b and 2 containing CeIII ion exhibit a paramagnetic property with weak antiferromagnetic interactions between the two adjacent magnetic centers.

40 CFR 721.9511 - Silicic acid (H6SiO2O7), magnesium, strontium salt(1:1:2), dysprosium and europium-doped.

Code of Federal Regulations, 2010 CFR

2010-07-01

... ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.9511 Silicic acid (H6SiO2O7), magnesium, strontium salt(1:1:2), dysprosium and europium-doped. (a) Chemical substance and significant new...

2,3-Diamino-pyridinium sorbate-sorbic acid (1/1).

PubMed

Hemamalini, Madhukar; Goh, Jia Hao; Fun, Hoong-Kun

2012-01-01

In the title mol-ecular salt-adduct, C(5)H(8)N(3) (+)·C(6)H(7)O(2) (-)·C(6)H(8)O(2), the 2,3-diamino-pyridinium cation is essentially planar, with a maximum deviation of 0.013 (2) Å, and is protanated at its pyridine N atom. The sorbate anion and sorbic acid mol-ecules exist in extended conformations. In the crystal, the protonated N atom and one of the two amino-group H atoms are hydrogen bonded to the sorbate anion through a pair of N-H⋯O hydrogen bonds, forming an R(1) (2)(6) ring motif. The carboxyl groups of the sorbic acid mol-ecules and the carboxyl-ate groups of the sorbate anions are connected via O-H⋯O hydrogen bonds. Furthermore, the ion pairs and neutral mol-ecules are connected via inter-molecular N-H⋯O hydrogen bonds, forming sheets lying parallel to (100).

Orphenadrinium picrate picric acid.

PubMed

Fun, Hoong-Kun; Hemamalini, Madhukar; Siddaraju, B P; Yathirajan, H S; Narayana, B

2010-02-24

The asymmetric unit of the title compound N,N-dimethyl-2-[(2-methyl-phen-yl)phenyl-meth-oxy]ethanaminium picrate picric acid, C(18)H(24)NO(+)·C(6)H(2)N(3)O(7) (-)·C(6)H(3)N(3)O(7), contains one orphenadrinium cation, one picrate anion and one picric acid mol-ecule. In the orphenadrine cation, the two aromatic rings form a dihedral angle of 70.30 (7)°. There is an intra-molecular O-H⋯O hydrogen bond in the picric acid mol-ecule, which generates an S(6) ring motif. In the crystal structure, the orphenadrine cations, picrate anions and picric acid mol-ecules are connected by strong inter-molecular N-H⋯O hydrogen bonds, π⋯π inter-actions between the benzene rings of cations and anions [centroid-centroid distance = 3.5603 (9) Å] and weak C-H⋯O hydrogen bonds, forming a three-dimensional network.

Dye-sensitized solar cell characteristics of nanocomposite zinc ferrite working electrode: effect of composite precursors and titania as a blocking layer on photovoltaic performance.

PubMed

Habibi, Mohammad Hossein; Habibi, Amir Hossein; Zendehdel, Mahmoud; Habibi, Mehdi

2013-06-01

This research investigates the performance of a zinc ferrite (ZF) as working electrodes in a dye-sensitized solar cell (DSSC). This ZF working electrode was prepared by sol-gel and thermal decomposition of four different precursors including: zinc acetate dihydrate (Zn(CH3COO)2·2H2O), ferric nitrate nonahydrate (Fe(NO3)3·9H2O), iron(III) acetate; Fe(C2H3O2)3, and zinc nitrate hexahydrate, Zn(NO3)2·6H2O. The effects of annealing temperature and precursors on the structural, morphological, and optical properties were investigated. The field emission scanning electron microscope images (FESEM) and scanning electron microscopy (SEM) show that ZFe films are polycrystalline in nature and homogeneous with densely packed grains. Nanoporous zinc ferrite coatings were prepared by doctor blade technique on the fluorine-doped tin oxide (FTO) and used as working electrodes in DSSC. In all DSSCs, platinized FTO and [Co(bpy)3](2+/3+) in 3-methoxy proponitrile were used as counter electrode and redox mediator system respectively. Comparing the fill factors of four different zinc ferrite nanocomposites, the highest fill factor was for ZnFe2O4-TBL sample. Cell fabricated with ZnFeA working electrode shows relatively higher Jsc. Copyright © 2013 Elsevier B.V. All rights reserved.

Synthesis, crystal structures and luminescence properties of new multi-component co-crystals of isostructural Co(II) and Zn(II) complexes

NASA Astrophysics Data System (ADS)

Tella, Adedibu C.; Owalude, Samson O.; Omotoso, Mary F.; Olatunji, Sunday J.; Ogunlaja, Adeniyi S.; Alimi, Lukman O.; Popoola, Olugbenga K.; Bourne, Susan A.

2018-04-01

Two novel isostructural compounds containing multi-component co-crystals [M(C6H4NO2)2(H2O)2](C9H6O6)2 (M = Co (1), Zn (2), C6H4NO2 = Picolinic acid, C9H6O6 = Trimesic acid) have been synthesized. The compounds were characterized by elemental analysis, FT-IR, UV-Visible and 1H NMR spectroscopies as well as thermal and single crystal X-ray diffraction analyses. Single crystal X-ray diffraction analysis reveals that 1 and 2 are isostructural. Compound 1 crystallizes in triclinic space group (P-1, with a = 5.154 (10) Å, b = 11.125 (2) Å, c = 14.113 (3) Å, α = 91.01 (3)°, β = 100.54 (3)°, and γ = 102.71 (3)°). In a similar fashion, compound 2 crystallizes in triclinic space group (P-1, with a = 5.1735 (3) Å, b = 11.0930 (10) Å, c = 14.1554 (8) Å, α = 91.70 (3)°, β = 100.26 (3)°, γ = 102.90 (3)°). The metal (II) cation presents distorted MN2O4 octahedral geometry with H2O molecules coordinated to the metal in equatorial position while the picolinic acid molecules are axially coordinated through the pyridine N atom. The two trimesic acid molecules are not part of the first coordination sphere. Compounds 1 and 2 constitute an example of a class of coordination compound of multicomponent crystals having trimesic acid outside the coordination sphere where it is neither protonated or deprotonated. The two compounds were investigated for luminiscence properties.

Interactions of methylamine and ammonia with atmospheric nucleation precursor H{sub 2}SO{sub 4} and common organic acids: Thermodynamics and atmospheric implications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Y.; Jiang, L.; Bai, Z.

Interactions of the two common atmospheric bases, ammonia (NH{sub 3}) and methylamine MA (CH{sub 3}NH{sub 2}), which are considered to be important stabilizers of binary clusters in the Earth’s atmosphere, with H{sub 2}SO{sub 4}, the key atmospheric precursor, and 14 common atmospheric organic acids (COA) (formic (CH{sub 2}O{sub 2}), acetic (C{sub 2}H{sub 4}O{sub 2}), oxalic (C{sub 2}H{sub 2}O{sub 4}), malonic (C{sub 3}H{sub 4}O{sub 4}), succinic (C{sub 4}H{sub 6}O{sub 4}), glutaric acid (C{sub 5}H{sub 8}O{sub 4}), adipic (C{sub 6}H{sub 10}O{sub 4}), benzoic (C{sub 6}H{sub 5}COOH), phenylacetic (C{sub 6}H{sub 5}CH{sub 2}COOH), pyruvic (C{sub 3}H{sub 4}O{sub 3}), maleic acid (C{sub 4}H{sub 4}O{sub 4}),more » malic (C{sub 4}H{sub 6}O{sub 5}), tartaric (C{sub 4}H{sub 6}O{sub 6}) and pinonic acid (C{sub 10}H{sub 16}O{sub 3})) have been studied using the composite high-accuracy G3MP2 method. The thermodynamic stability of mixed (COA) (H{sub 2}SO{sub 4}), (COA)(B1) and (COA)(B2) dimers and (COA) (H{sub 2}SO{sub 4}) (B1) and (COA) (H{sub 2}SO{sub 4}) (B1) trimers, where B1 and B2 represent methylamine (CH{sub 3}NH{sub 2}) and ammonia (NH{sub 3}), respectively, have been investigated and their impacts on the thermodynamic stability of clusters containing H{sub 2}SO{sub 4} have been analyzed. It has been shown that in many cases the interactions of H{sub 2}SO{sub 4} with COA, ammonia and methylamine lead to the formation of heteromolecular dimers and trimers, which are certainly more stable than (H{sub 2}SO{sub 4}){sub 2} and (H{sub 2}SO{sub 4}){sub 3}. It has also been found that free energies of (COA) (H{sub 2}SO{sub 4})+ CH{sub 3}NH{sub 2}⇔(COA) (H{sub 2}SO{sub 4})(CH{sub 3}NH{sub 2}) reactions exceed 10-15 kcal mol{sup −1}. This is a clear indication that mixed trimers composed of COA, H{sub 2}SO{sub 4} and methylamine are very stable and can thus serve as possible nucleation sites. The present study leads us to conclude that the interactions of COA coexisting with H{sub 2}SO{sub 4} and common atmospheric bases in the Earth’s atmosphere may be an important factor affecting the stability of nucleating sulfuric acid clusters and that the impacts of COA on atmospheric nucleation should be studied in further details.« less

Determination of hydrolyzable tannins in the fruit of Terminalia chebula Retz. by high-performance liquid chromatography and capillary electrophoresis.

PubMed

Juang, Lih-Jeng; Sheu, Shuenn-Jyi; Lin, Ta-Chen

2004-06-01

A RP-HPLC method for determining fourteen components (gallic acid, chebulic acid, 1,6-di-O-galloyl-D-glucose, punicalagin, 3,4,6-tri-O-galloyl-D-glucose, casuarinin, chebulanin, corilagin, neochebulinic acid, terchebulin, ellagic acid, chebulagic acid, chebulinic acid, and 1,2,3,4,6-penta-O-galloyl-D-glucose) in the fruit of Terminalia chebula Retz. is described. The separation was achieved within 80 min using a binary gradient with mobile phases consisting of a pH 2.7 phosphoric acid solution and an 80% CH3CN solution. Capillary electrophoretic analyses were also attempted, and it was found that CZE (25 mM Na2B4O7, 5 mM NaH2PO4, pH 7.0) was an efficient method for the separation of gallotannins, while an MEKC method (25 mM Na2B4O7, 5 mM NaH2PO4, 20 mM SDS, pH 7.0, and 10% acetonitrile) provided a better separation for most of the tannins examined. The HPLC and CE methods developed were both successfully applied to the assay of tannins in commercial samples of Chebulae Fructus.

One barbiturate and two solvated thiobarbiturates containing the triply hydrogen-bonded ADA/DAD synthon, plus one ansolvate and three solvates of their coformer 2,4-diaminopyrimidine.

PubMed

Hützler, Wilhelm Maximilian; Egert, Ernst; Bolte, Michael

2016-09-01

A path to new synthons for application in crystal engineering is the replacement of a strong hydrogen-bond acceptor, like a C=O group, with a weaker acceptor, like a C=S group, in doubly or triply hydrogen-bonded synthons. For instance, if the C=O group at the 2-position of barbituric acid is changed into a C=S group, 2-thiobarbituric acid is obtained. Each of the compounds comprises two ADA hydrogen-bonding sites (D = donor and A = acceptor). We report the results of cocrystallization experiments of barbituric acid and 2-thiobarbituric acid, respectively, with 2,4-diaminopyrimidine, which contains a complementary DAD hydrogen-bonding site and is therefore capable of forming an ADA/DAD synthon with barbituric acid and 2-thiobarbituric acid. In addition, pure 2,4-diaminopyrimidine was crystallized in order to study its preferred hydrogen-bonding motifs. The experiments yielded one ansolvate of 2,4-diaminopyrimidine (pyrimidine-2,4-diamine, DAPY), C4H6N4, (I), three solvates of DAPY, namely 2,4-diaminopyrimidine-1,4-dioxane (2/1), 2C4H6N4·C4H8O2, (II), 2,4-diaminopyrimidine-N,N-dimethylacetamide (1/1), C4H6N4·C4H9NO, (III), and 2,4-diaminopyrimidine-1-methylpyrrolidin-2-one (1/1), C4H6N4·C5H9NO, (IV), one salt of barbituric acid, viz. 2,4-diaminopyrimidinium barbiturate (barbiturate is 2,4,6-trioxopyrimidin-5-ide), C4H7N4(+)·C4H3N2O3(-), (V), and two solvated salts of 2-thiobarbituric acid, viz. 2,4-diaminopyrimidinium 2-thiobarbiturate-N,N-dimethylformamide (1/2) (2-thiobarbiturate is 4,6-dioxo-2-sulfanylidenepyrimidin-5-ide), C4H7N4(+)·C4H3N2O2S(-)·2C3H7NO, (VI), and 2,4-diaminopyrimidinium 2-thiobarbiturate-N,N-dimethylacetamide (1/2), C4H7N4(+)·C4H3N2O2S(-)·2C4H9NO, (VII). The ADA/DAD synthon was succesfully formed in the salt of barbituric acid, i.e. (V), as well as in the salts of 2-thiobarbituric acid, i.e. (VI) and (VII). In the crystal structures of 2,4-diaminopyrimidine, i.e. (I)-(IV), R2(2)(8) N-H...N hydrogen-bond motifs are preferred and, in two structures, additional R3(2)(8) patterns were observed.

Two- and three-dimensional lanthanide-organic frameworks constructed using 1-hydro-6-oxopyridine-3-carboxylate and oxalate ligands.

PubMed

Liu, Cai-Ming; Xiong, Ming; Zhang, De-Qing; Du, Miao; Zhu, Dao-Ben

2009-08-07

6-Hydroxypyridine-3-carboxylic acid (6-HOPy-3-CO(2)H) reacts with Ln(2)O(3) (Ln = Nd, Sm, Eu, Gd) and oxalic acid (H(2)OX) under hydrothermal conditions to generate four novel lanthanide-organic coordination polymeric networks [Ln(2)(1H-6-Opy-3-CO(2))(2)(OX)(2)(H(2)O)(3)] x 2.5 H(2)O (Ln = Nd, 1; Sm, 2; 1H-6-Opy-3-CO(2)(-) = 1-hydro-6-oxopyridine-3-carboxylate) and [Ln(1H-6-Opy-3-CO(2))(OX)(H(2)O)(2)] x H(2)O (Ln = Eu, 3; Gd, 4). The new co-ligand 1H-6-Opy-3-CO(2)(-) anion was generated by the autoisomerization of the single deprotonated 6-HOPy-3-CO(2)(-) anion (from the enol form into the ketone one). 1 and 2 are isomorphous, they possess a three-dimensional architecture constructed from Ln(3+) ions bridged by oxalate anions and two types of 1H-6-Opy-3-CO(2)(-) bridges, showing a three-nodal (4,5)-connected topology (3.4(2).5(2).6(3).7.8)(2)(3.5(3).6(2))(2)(3(2).6.7(2).8) or a simplified uninodal 6-connected topology (3(3).4(6).5(5).6), both topologies are completely new; while only one type of 1H-6-Opy-3-CO(2)(-) bridge is used to construct the two-dimensional layer networks of 3 and 4 besides oxalate bridges, both complexes 3 and 4 are isostructural, exhibiting the honeycomb topology 6(3). The lanthanide contraction effect is believed to play a key role in directing the formation of a particular structure. A magnetic study of 1-3 indicated that the coupling interaction between Ln(3+) ions is weak.

Carboxylate ligands induced structural diversity of zinc(II) coordination polymers based on 3,6-bis(imidazol-1-yl)carbazole: Syntheses, structures and photocatalytic properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheng, Hong-Jian, E-mail: hjcheng@cslg.cn; Tang, Hui-Xiang; Shen, Ya-Li

2015-12-15

Solvothermal reactions of Zn(NO{sub 3}){sub 2}·6H{sub 2}O with 3,6-bis(1-imidazolyl)carbazole (3,6-bmcz) and 1,4-benzenedicarboxylic acid (1,4-H{sub 2}bdc), p-phenylenediacetic acid (p-H{sub 2}pda), benzophenone-4,4-dicarboxylic acid (H{sub 2}bpda) afforded three coordination polymers [Zn(1,4-bdc)(3,6-bmcz)]{sub n} (1), {[Zn(p-pda)(3,6-bmcz)]·1.5H_2O}{sub n} (2) and {[Zn(bpda)(3,6-bmcz)]·0.25H_2O}{sub n} (3). Complexes 1–3 were characterized by elemental analysis, IR, powder X-ray diffraction, and single-crystal X-ray diffraction. Complex 1 shows 3D structure with 2D nets inclined polycatenation. Complexes 2 and 3 possess an extended 3D supramolecular architecture based on their respective 2D layers through hydrogen-bonding interactions and the π···π stacking interactions. The solid state luminescent and optical properties of 1–3 at ambient temperature were alsomore » investigated. A comparative study on their photocatalytic activity toward the degradation of methylene blue in polluted water was explored. - Graphical abstract: Reactions of Zn(NO{sub 3}){sub 2} and 3,6-(1-imidazolyl)carbazole with 1,4-benzenedicarboxylic acid, p-phenylenediacetic acid or benzophenone-4,4-dicarboxylic acid afforded three coordination polymers with different topologies and photocatalytic activity. - Highlights: • Reactions of 1,4-H{sub 2}bdc, p-H{sub 2}pda or H{sub 2}bpda with 3,6-bmcz and Zn(II) gave three CPs. • Complex 1 is a 3D entanglement. • Complex 2 or 3 is a 3D supramolecular structure based on different 2D layers. • Complex 2 exhibited good catalytic activity of methylene blue photodegradation.« less

Probing the Influence of Acidity and Temperature to Th(IV) on Hydrolysis, Nucleation, and Structural Topology.

PubMed

Lin, Jian; Qie, Meiying; Zhang, Linjuan; Wang, Xiaomei; Lin, Yuejian; Liu, Wei; Bao, Hongliang; Wang, Jianqiang

2017-11-20

Systematic control of the molar ratio between thorium hydroxides and selenic acid and their reaction temperature under hydrothermal conditions results in four novel thorium-based selenate complexes, namely, [Th 8 O 4 (OH) 8 (SeO 4 ) 6 (H 2 O) 16 ]·(SeO 4 ) 2 ·13H 2 O (Th-1), [Th 8 O 4 (OH) 8 (SeO 4 ) 8 (H 2 O) 13 ]·7H 2 O (Th-2), Th(OH) 2 (SeO 4 )H 2 O (Th-3), and Th 3 (SeO 4 ) 6 (H 2 O) 6 ·2.5H 2 O (Th-4), as well as the thorium mixed selenite selenate compound Th(SeO 3 )(SeO 4 ) (Th-5). Smaller [H 2 SeO 4 ]/[Th(IV)] ratio or lower temperature give rise to the formation of octameric [Th 8 (μ 3 -O) 4 (μ 2 -OH) 8 ] 16+ cores in Th-1/Th-2 and infinite [Th(μ 2 -OH) 2 H 2 O] 2+ chains in Th-3, respectively. Increasing the [H 2 SeO 4 ]/[Th(IV)] ratio or elevating the temperature generates a microporous (11.3 Å voids) open-framework Th-4, a monomeric thorium species without oxo/hydroxyl ligands, and a three-dimensional thorium structure Th-5. Formation of these compounds suggests that variables including acidity and temperature play a critical role in the hydrolysis and oligomerization of Th IV ions. Increasing acidity limits the deprotonation of water molecules and formation of nucleophilic hydroxo/oxo-aquo Th species, and high temperature appears to suppress the olation/oxolation hydrolysis reactions, which in both ways limit the formation of the thorium oligomers.

Simultaneous removal of 2,4,6-tribromophenol from water and bromate ion minimization by ozonation.

PubMed

Gounden, Asogan N; Singh, Sooboo; Jonnalagadda, Sreekantha B

2018-06-02

The study investigates the degradation of 2,4,6-tribromophenol (2,4,6-TBP) and the influence of solution pH, alkalinity, H 2 O 2 and O 3 dosage. Debromination efficiency of 2,4,6-TBP was the highest in basic water (pH = 10.61). The extent of TOC removal compared favourably with the amount of substrate converted, suggesting favourable mineralization of oxygenated by-products (OBPs). Ozonation in basic water favoured the formation of toxicBrO 3 - , while in acidic water (pH = 2.27) BrO 3 - yield was lowest. In acidic water the presence of CO 3 2- showed negligible effect on conversion, TOC and  BrO 3 - yield compared to ozonation alone. In basic water both 2,4,6-TBP conversion and TOC removal decreased with an increase in CO 3 2- , hence minimizing BrO 3 - formation. The O 3 /H 2 O 2 process showed an improvement in the debromination efficiency and TOC data revealed that total mineralization of OBP's was achieved. However, only 10% H 2 O 2 was able to effectively decrease BrO 3 - formation. Increasing the ozone concentration from 20 to 100 ppm enhanced the conversion of 2,4,6-TBP and TOC removal. At low ozone concentrations poor mineralization of OBP's occurred, while complete mineralization was achieved at higher ozone dose. The reaction pathways for ozone degradation of 2,4,6-TBP in acidic and basic waters is proposed. Copyright © 2018 Elsevier B.V. All rights reserved.

Crystal structures of eight 3D molecular adducts derived from bis-imidazole, bis(benzimidazole), and organic acids

NASA Astrophysics Data System (ADS)

Ding, Aihua; Jin, Shouwen; Jin, Shide; Hu, KaiKai; Lin, Zhihao; Liu, Hui; Wang, Daqi

2018-01-01

Cocrystallization of the bis(imidazole)/bis(benzimidazole) with a series of organic acids gave a total of eight molecular adducts with the compositions: (3,6-bis(imidazole-1-yl)pyridazine): (trichloroacetic acid)2(1) [(H2L1)2+ · (tca-)2, L1 = 3,6-bis(imidazole-1-yl)pyridazine, tca- = trichloroacetate], (bis(N-imidazolyl)methane): (suberic acid) (2) [(L2) · (H2suba), L2 = bis(N-imidazolyl)methane, H2suba = suberic acid], bis(N-imidazolyl)methane: (3-nitrophthalic acid): 3H2O (3) [(H2L2)2+ · (3-Hnpa-)2 · 3H2O, 3-Hnpa- = 3-nitro hydrogenphthalate], (bis(N-imidazolyl)butane)0.5: (4-nitrophthalic acid): H2O (4) [(H2L3)0.5+ · (4-Hnpa-)- · H2O, L3 = bis(N-imidazolyl)butane, 4-Hnpa- = 4-nitro hydrogenphthalate], (1-(3-(1H-benzimidazol-1-yl)propyl)-1H-benzimidazole): (3,5-dinitrosalicylic acid) (5) [(HL4) · (3,5-dns-), L4 = 1-(3-(1H-benzimidazol-1-yl)propyl)-1H-benzimidazole, 3,5-dns- = 3,5-dinitrosalicylate], (1-(3-(1H-benzimidazol-1-yl)propyl)-1H-benzimidazole): (3-nitrophthalic acid) (6) [(H2L4) · (3-npa2-), L4 = 1-(3-(1H-benzimidazol-1-yl)propyl)-1H-benzimidazole, 3-npa2-=3-nitrogenphthalate], (bis(N-imidazolyl)butane): (pamoic acid) (7) [(H2L3) · (pam), pam = pamoate], and (3,6-bis(imidazole-1-yl)pyridazine): (1,5-naphthalenedisulfonic acid) [(H2L1)2+ · (npda)2- = 1,5-naphthalenedisulfonate] (8). The eight adducts have been characterized by X-ray diffraction technique, infrared spectrum, and elemental analysis, and the melting points of all adducts were also reported. And their structural and supramolecular aspects are fully analyzed. The result reveals that among the eight investigated crystals both the end ring N in the bis(imidazole) moieties are protonated when the organic acids are deprotonated except 2, and 5, and the crystal packing is interpreted in terms of the strong ionic Nsbnd H⋯O H-bond between the imidazolium and the deprotonated acidic groups. Except the Nsbnd H⋯O H-bond, the Osbnd H⋯O H-bonds were also found at the salts 3, 4, 5, and 7, salt 5 has the additional Nsbnd H⋯N H-bond, the Nsbnd H⋯S H-bond was established at 8. Further analysis of the crystal packing of the adducts indicated that a different set of additional CHsbnd O/CH2sbnd O, CHsbnd Cl, CH-π/CH2-π, Clsbnd C, Clsbnd N, Osbnd O, O-π, OH-π, and π-π associations contribute to the stabilization and expansion of the total 3D frameworks. For the coexistence of the various weak interactions these structures had homo or hetero supramolecular synthons or both. Some supramolecular synthons, such as R12(4), R22(7), and R22(8) usually found in crystals of organic acids with imidazole unit, were again shown to be appeared in constructing most of these H-bond networks.

Electrochemical deposited nickel nanowires: influence of deposition bath temperature on the morphology and physical properties

NASA Astrophysics Data System (ADS)

Sofiah, A. G. N.; Kananathan, J.; Samykano, M.; Ulakanathan, S.; Lah, N. A. C.; Harun, W. S. W.; Sudhakar, K.; Kadirgama, K.; Ngui, W. K.; Siregar, J. P.

2017-10-01

This paper investigates the influence of the electrolytic bath temperature on the morphology and physical properties of nickel (Ni) nanowires electrochemically deposited into the anodic alumina oxide porous membrane (AAO). The synthesis was performed using nickel sulfate hexahydrate (NiSO4.6H2O) and boric acid (H3BO3) as an electrolytic bath for the electrochemical deposition of Ni nanowires. During the experiment, the electrolyte bath temperature varied from 40°C, 80°C, and 120°C. After the electrochemical deposition process, AAO templates cleaned with distilled water preceding to dissolution in sodium hydroxide (NaOH) solution to obtain free-standing Ni nanowires. Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive Spectroscopy (EDX) and X-ray Diffraction (XRD) analysis were employed to characterize the morphology and physical properties of the synthesized Ni nanowires. Finding reveals the electrodeposition bath temperature significantly influences the morphology and physical properties of the synthesized Ni nanowires. Rougher surface texture, larger crystal size, and longer Ni nanowires obtained as the deposition bath temperature increased. From the physical properties properties analysis, it can be concluded that deposition bath temperature influence the physical properties of Ni nanowires.

Proton-transfer compounds with 4-amino-N-(4,6-dimethylpyrimidin-2-yl)benzenesulfonamide (sulfamethazine): the structures and hydrogen bonding in the salts with 5-nitrosalicylic acid and picric acid.

PubMed

Smith, Graham; Wermuth, Urs D

2013-05-01

The structures of the anhydrous proton-transfer compounds of the sulfa drug sulfamethazine with 5-nitrosalicylic acid and picric acid, namely 2-(4-aminobenzenesulfonamido)-4,6-dimethylpyrimidinium 2-hydroxy-5-nitrobenzoate, C12H15N4O2S(+)·C7H4NO4(-), (I), and 2-(4-aminobenzenesulfonamido)-4,6-dimethylpyrimidinium 2,4,6-trinitrophenolate, C12H15N4O2S(+)·C6H2N3O7(-), (II), respectively, have been determined. In the asymmetric unit of (I), there are two independent but conformationally similar cation-anion heterodimer pairs which are formed through duplex intermolecular N(+)-H···O(carboxylate) and N-H···O(carboxylate) hydrogen-bond pairs, giving a cyclic motif [graph set R2(2)(8)]. These heterodimers form separate and different non-associated substructures through aniline N-H···O hydrogen bonds, one one-dimensional, involving carboxylate O-atom acceptors, the other two-dimensional, involving both carboxylate and hydroxy O-atom acceptors. The overall two-dimensional structure is stabilized by π-π interactions between the pyrimidinium ring and the 5-nitrosalicylate ring in both heterodimers [minimum ring-centroid separation = 3.4580 (8) Å]. For picrate (II), the cation-anion interaction involves a slightly asymmetric chelating N-H···O R2(1)(6) hydrogen-bonding association with the phenolate O atom, together with peripheral conjoint R1(2)(6) interactions between the same N-H groups and O atoms of the ortho-related nitro groups. An inter-unit amine N-H···O(sulfone) hydrogen bond gives one-dimensional chains which extend along a and inter-associate through π-π interactions between the pyrimidinium rings [centroid-centroid separation = 3.4752 (9) Å]. The two structures reported here now bring to a total of four the crystallographically characterized examples of proton-transfer salts of sulfamethazine with strong organic acids.

Crystal structure of a 2:1 piroxicam–gentisic acid co-crystal featuring neutral and zwitterionic piroxicam molecules

DOE Office of Scientific and Technical Information (OSTI.GOV)

Horstman, Elizabeth M.; Bertke, Jeffery A.; Woods, Toby J.

2016-11-04

A new 2:1 co-crystal of piroxicam and gentisic acid [systematic name: 4-hydroxy-1,1-dioxo-N-(pyridin-2-yl)-2H-1λ 6,2-benzothiazine-3-carboxamide–2-(4-oxido-1,1-dioxo-2H-1λ 6,2-benzothiazine-3-amido)pyridin-1-ium–2,5-dihydroxybenzoic acid, 2C 15H 13N 3O 4S·C 7H 6O 4] has been synthesized using a microfluidic platform and initially identified using Raman spectroscopy. In the co-crystal, one piroxicam molecule is in its neutral form and an intramolecular O—H...O hydrogen bond is observed. The other piroxicam molecule is zwitterionic (proton transfer from the OH group to the pyridine N atom) and two intramolecular N—H...O hydrogen bonds occur. The gentisic acid molecule shows whole-molecule disorder over two sets of sites in a 0.809(2):0.191(2) ratio. In the crystal, extensive hydrogenmore » bonding between the components forms layers propagating in theabplane.« less

A set of new transition metal-based coordination complexes dependent upon Hpztza ligand (Hpztza=2-(5-(pyrazin-2-yl)-2H-tetrazol-2-yl) acetic acid)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang Jie; Shen Lei; Yang Gaowen, E-mail: ygwsx@126.com

2012-02-15

Reaction of MCl{sub 2}{center_dot}4H{sub 2}O (M=Zn, Cd, Mn, Co, Ni) with 2-(5-(pyrazin-2-yl)-2H-tetrazol-2-yl) acetic acid (Hpztza) yielded a set of new M(II)/pztza complexes, [Cd(pztza){sub 2}(H{sub 2}O){sub 6}]{center_dot}3H{sub 2}O{center_dot}(Hpztza) (1), [M(pztza){sub 2}(H{sub 2}O){sub 2}; M=Cd(2), Zn(7), Mn(9)], [Cd(pztza){sub 2}]{center_dot}2(CH{sub 3}OH) (3), [Co(pztza){sub 2}(H{sub 2}O){sub 2}]{center_dot}6H{sub 2}O (4), [Co(pztza)(H{sub 2}O)Cl] (6) and [M(pztza){sub 2}(H{sub 2}O){sub 2}]{center_dot}2H{sub 2}O [M=Co(5), Zn(8), Ni(10)]. These compounds were structurally characterized by elemental analysis, IR spectroscopy and X-ray single-crystal diffraction. Complex 1 featured a mononuclear structure, complexes 4, 5, 7, 8, 10 showed 1D chains and complexes 2, 3, 6, 9 displayed 2D layer structures. Furthermore, the luminescence propertiesmore » of 1-10 were investigated at room temperature in the solid state. - Graphical abstract: Ten new coordination polymers with 2-(5-(pyrazin-2-yl)-2H-tetrazol-2-yl) acetic acid (Hpztza) ligand have been synthesized and their structures have been characterized. All of the complexes show photoluminescence at room temperature. Highlights: Black-Right-Pointing-Pointer Ten novel transition metal-based coordination complexes with 2-(5-(pyrazin-2-yl)-2H-tetrazol-2-yl) acetic acid (Hpztza) are reported. Black-Right-Pointing-Pointer Complexes 1-10 are described as mononuclear structure, 1D and 2D frameworks with diverse architecture. Black-Right-Pointing-Pointer Six coordination complexes show emission at room temperature in the solid state.« less

Synthesis of boron suboxide from boron and boric acid under mild pressure and temperature conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiao, Xiaopeng; Jin, Hua; Ding, Zhanhui

2011-05-15

Graphical abstract: Well-crystallized and icosahedral B{sub 6}O crystals were prepared by reacting boron and boric acid at milder reaction conditions (1 GPa and 1300 {sup o}C for 2 h) as compared to previous work.. Research highlights: {yields} Well-crystallized icosahedral B{sub 6}O was synthesized by reacting boric acid and boron. {yields} The synthesis conditions (1 GPa and 1300 {sup o}C for 2 h) are milder in comparison with previous work. {yields} The more practical synthesis method may make B{sub 6}O as a potential substitute for diamond in industry. -- Abstract: Boron suboxide (B{sub 6}O) was synthesized by reacting boron and boricmore » acid (H{sub 3}BO{sub 3}) at pressures between 1 and 10 GPa, and at temperatures between 1300 and 1400 {sup o}C. The B{sub 6}O samples prepared were icosahedral with diameters ranging from 20 to 300 nm. Well-crystallized and icosahedral crystals with an average size of {approx}100 nm can be obtained at milder reaction conditions (1 GPa and 1300 {sup o}C for 2 h) as compared to previous work. The bulk B{sub 6}O sample was stable in air at 600 {sup o}C and then slowly oxidized up to 1000 {sup o}C. The relatively mild synthetic conditions developed in this study provide a more practical synthesis of B{sub 6}O, which may potentially be used as a substitute for diamond in industry as a new superhard material.« less

2,4,6-Tri­amino-1,3,5-triazin-1-ium 3-(prop-2-eno­yloxy)propano­ate acrylic acid monosolvate monohydrate

PubMed Central

Sangeetha, V.; Kanagathara, N.; Chakkaravarthi, G.; Marchewka, M. K.; Anbalagan, G.

2013-01-01

The asymmetric unit of the title salt, C3H7N6 +·C6H7O4 −·C3H4O2·H2O, contains a 2,4,6-tri­amino-1,3,5-triazin-1-ium cation, a 3-(prop-2-eno­yloxy)propano­ate anion and acrylic acid and water solvent mol­ecules in a 1:1:1:1 ratio and with each species in a general position. In the crystal, the components are linked into a supra­molecular layer in the bc plane via a combination of O—H⋯O, N—H⋯N and N—H⋯O hydrogen bonding. The crystal studied was a non-merohedral twin, the minor component contribution being approximately 26%. PMID:23723892

Structure, vibrations and quantum chemical investigations of hydrogen bonded complex of bis(1-hydroxy-2-methylpropan-2-aminium)selenate

NASA Astrophysics Data System (ADS)

Thirunarayanan, S.; Arjunan, V.; Marchewka, M. K.; Mohan, S.

2017-04-01

The hydrogen bonded molecular complex bis(1-hydroxy-2-methylpropan-2-aminium)selenate (C8H24N2O6Se) has been prepared by the reaction of 2-amino-2-methyl propanol and selenic acid. The X-ray diffraction analysis revealed that the intermolecular proton transfer from selenic acid (SeO4H2) to 2-amino-2-methylpropanol results in the formation of bis(1-hydroxy-2-methylpropan-2-aminium)selenate (HMPAS) salt and the fragments are connected through H-bonding and ion pairing. The N-H⋯O and O-H⋯O interactions between 2-amino-2-methylpropanol and selenic acid determine the supramolecular arrangement in three-dimensional space. The salt crystallises in the space group P121/n1 of monoclinic system. The complete vibrational assignments of HMPAS have been performed by FTIR and FT-Raman spectroscopy. The experimental data are correlated with the structural properties namely the energy, thermodynamic parameters, atomic charges, hybridization concepts and vibrational frequencies determined by quantum chemical studies performed with B3LYP method using 6-311++G*, 6-31+G* and 6-31G** basis sets.

Volume properties and refraction of aqueous solutions of bisadducts of light fullerene C60 and essential amino acids lysine, threonine, and oxyproline (C60(C6H13N2O2)2, C60(C4H8NO3)2, and C60(C5H9NO2)2) at 25°C

NASA Astrophysics Data System (ADS)

Semenov, K. N.; Ivanova, N. M.; Charykov, N. A.; Keskinov, V. A.; Kalacheva, S. S.; Duryagina, N. N.; Garamova, P. V.; Kulenova, N. A.; Nabieva, A.

2017-02-01

Concentration dependences of the density of aqueous solutions of bisadducts of light fullerene C60 and essential amino acids are studied by pycnometry. Concentration dependences of the average molar volumes and partial volumes of components (H2O and corresponding bisadducts) are calculated for C60(C6H13N2O2)2-H2O, C60(C4H8NO3)2-H2O, and C60(C5H9NO2)2-H2O binary systems at 25°C. Concentration dependences of the indices of refraction of C60(C6H13N2O2)2-H2O, C60(C4H8NO3)2-H2O, and C60(C5H9NO2)2-H2O binary systems are determined at 25°C. The concentration dependences of specific refraction and molar refraction of bisadducts and aqueous solutions of them are calculated.

Chlorogenic acid analogues from Gynura nepalensis protect H9c2 cardiomyoblasts against H2O2-induced apoptosis

PubMed Central

Yu, Bang-wei; Li, Jin-long; Guo, Bin-bin; Fan, Hui-min; Zhao, Wei-min; Wang, He-yao

2016-01-01

Aim: Chlorogenic acid has shown protective effect on cardiomyocytes against oxidative stress-induced damage. Herein, we evaluated nine caffeoylquinic acid analogues (1–9) isolated from the leaves of Gynura nepalensis for their protective effect against H2O2-induced H9c2 cardiomyoblast damage and explored the underlying mechanisms. Methods: H9c2 cardiomyoblasts were exposed to H2O2 (0.3 mmol/L) for 3 h, and cell viability was detected with MTT assay. Hoechst 33342 staining was performed to evaluate cell apoptosis. MMPs (mitochondrial membrane potentials) were measured using a JC-1 assay kit, and ROS (reactive oxygen species) generation was measured using CM-H2 DCFDA. The expression levels of relevant proteins were detected using Western blot analysis. Results: Exposure to H2O2 markedly decreased the viability of H9c2 cells and catalase activity, and increased LDH release and intracellular ROS production; accompanied by a loss of MMP and increased apoptotic rate. Among the 9 chlorogenic acid analogues as well as the positive control drug epigallocatechin gallate (EGCG) tested, compound 6 (3,5-dicaffeoylquinic acid ethyl ester) was the most effective in protecting H9c2 cells from H2O2-induced cell death. Pretreatment with compound 6 (1.56–100 μmol/L) dose-dependently alleviated all the H2O2-induced detrimental effects. Moreover, exposure to H2O2 significantly increased the levels of Bax, p53, cleaved caspase-8, and cleaved caspase-9, and decreased the level of Bcl-2, resulting in cell apoptosis. Exposure to H2O2 also significantly increased the phosphorylation of p38, JNK and ERK in the H9c2 cells. Pretreatment with compound 6 (12.5 and 25 μmol/L) dose-dependently inhibited the H2O2-induced increase in the level of cleaved caspase-9 but not of cleaved caspase-8. It also dose-dependently suppressed the H2O2-induced phosphorylation of JNK and ERK but not that of p38. Conclusion: Compound 6 isolated from the leaves of Gynura nepalensis potently protects H9c2 cardiomyoblasts against H2O2-induced apoptosis, possibly by inhibiting intrinsic apoptosis and the ERK/JNK pathway. PMID:27593219

Series of mixed uranyl-lanthanide (Ce, Nd) organic coordination polymers with aromatic polycarboxylates linkers.

PubMed

Mihalcea, Ionut; Volkringer, Christophe; Henry, Natacha; Loiseau, Thierry

2012-09-17

Three series of mixed uranyl-lanthanide (Ce or Nd) carboxylate coordination polymers have been successfully synthesized by means of a hydrothermal route using either conventional or microwave heating methods. These compounds have been prepared from mixtures of uranyl nitrate, lanthanide nitrate together with phthalic acid (1,2), pyromellitic acid (3,4), or mellitic acid (5,6) in aqueous solution. The X-ray diffraction (XRD) single-crystal revealed that the phthalate complex (UO(2))(4)O(2)Ln(H(2)O)(7)(1,2-bdc)(4)·NH(4)·xH(2)O (Ln = Ce(1), Nd(2); x = 1 for 1, x = 0 for 2), is based on the connection of tetranuclear uranyl-centered building blocks linked to discrete monomeric units LnO(2)(H(2)O)(7) via the organic species to generate infinite chains, intercalated by free ammonium cations. The pyromellitate phase (UO(2))(3)Ln(2)(H(2)O)(12)(btec)(3)·5H(2)O (Ce(3), Nd(4)) contains layers of monomeric uranyl-centered hexagonal and pentagonal bipyramids linked via the carboxylate arms of the organic molecules. The three-dimensionality of the structure is ensured by the connection of remaining free carboxylate groups with isolated monomeric units LnO(2)(H(2)O)(7). The network of the third series (UO(2))(2)(OH)Ln(H(2)O)(7)(mel)·5H(2)O (Ce(5), Nd(6)) is built up from dinuclear uranyl units forming layers through connection with the mellitate ligands, which are further linked to each other through discrete monomers LnO(3)(H(2)O)(6). The thermal decomposition of the various coordination complexes led to the formation of mixed uranium-lanthanide oxide, with the fluorite-type structure at 1500 °C (for 1, 2) or 1400 °C for 3-6. Expected U/Ln ratio from the crystal structures were observed for compounds 1-6.

Self-assembly of metal-organic supramolecules: from a metallamacrocycle and a metal-organic coordination cage to 1D or 2D coordination polymers based on flexible dicarboxylate ligands.

PubMed

Dai, Fangna; Dou, Jianmin; He, Haiyan; Zhao, Xiaoliang; Sun, Daofeng

2010-05-03

To assemble metal-organic supramolecules such as a metallamacrocycle and metal-organic coordination cage (MOCC), a series of flexible dicarboxylate ligands with the appropriate angle, 2,2'-(2,3,5,6-tetramethyl-1,4-phenylene)bis(methylene)bis(sulfanediyl)dibenzoic acid (H(2)L(1)), 2,2'-(2,5-dimethyl-1,4-phenylene)bis(methylene)bis(sulfanediyl)dibenzoic acid (H(2)L(2)), 2,2'-(2,4,6-trimethyl-1,3-phenylene)bis(methylene)bis(sulfanediyl)dinicotinic acid (H(2)L(3)), and 2,2'-(2,4,6-trimethyl-1,3-phenylene)bis(methylene)bis(sulfanediyl)dibenzoic acid (H(2)L(4)), have been designed and synthesized. Using these flexible ligands to assemble with metal ions, six metal-organic supramolecules, Cd(2)(L(1))(2)(dmf)(4)(H(2)O)(2).H(2)O (1), Mn(3)((1)L(2))(2)((2)L(2))(dmf)(2)(H(2)O)(2).5dmf (2), Cu(4)(L(3))(4)(H(2)O)(4).3dmf (3), Cu(4)(L(4))(4)(dmf)(2)(EtOH)(2).8dmf.6H(2)O (4), Mn(4)(L(4))(4)(dmf)(4)(H(2)O)(4).6dmf.H(2)O (5), and Mn(3)(L(4))(3)(dmf)(4).2dmf.3H(2)O (6), possessing a rectangular macrocycle, MOCCs or their extensions, and 1D or 2D coordination polymers, have been isolated. All complexes have been characterized by single-crystal X-ray diffraction, elemental analysis, and thermogravimetric analysis. Complex 1 is a discrete rectangular macrocycle, while complex 2 is a 2D macrocycle-based coordination polymer in which the L(2) ligand adopts both syn and anti conformations. Complexes 3-5 are discrete MOCCs in which two binuclear metal clusters are engaged by four organic ligands. The different geometries of the secondary building units (SBUs) and the axial coordinated solvates on the SBUs result in their different symmetries. Complex 6 is a 1D coordination polymer, extended from a MOCC made up of two metal ions and three L(4) ligands. All of the flexible dicarboxylate ligands adopt a syn conformation except that in complex 2, indicating that the syn conformational ligand is helpful for the formation of a metallamacrocycle and a MOCC. The magnetic properties of complexes 5 and 6 have also been studied.

Decaaquabis(μ3-4-hydroxypyridine-2,6-dicarboxylato)bis(4-hydroxypyridine-2,6-dicarboxylato)tetramanganese(II) 3.34-hydrate: a new three-dimensional open metal-organic framework based on a tetranuclear Mn(II) complex of chelidamic acid and undecameric stitching water clusters.

PubMed

Mirzaei, M; Lippolis, V; Eshtiagh-Hosseini, H; Mahjoobizadeh, M

2012-01-01

4-Hydroxypyridine-2,6-dicarboxylic acid (chelidamic acid, cdaH(3)) reacts with MnCl(2)·2H(2)O in the presence of 2-amino-4-methylpyrimidine in water to afford the tetranuclear title complex, [Mn(4)(C(8)H(3)NO(5))(4)(H(2)O)(10)]·3.34H(2)O, built through carboxylate bridging. The tetranuclear complex sits on a centre of inversion at (½, ½, ½). In the crystal, discrete undecameric (H(2)O)(10.34) water clusters (involving both coordinated and uncoordinated water molecules, with one site of an uncoordinated water molecule not fully occupied) assemble these tetranuclear Mn(II) complex units via an intricate array of hydrogen bonding into an overall three-dimensional network. The degree of structuring of the (H(2)O)(10.34) supramolecular association of water molecules observed in the present compound, imposed by its environment and vice versa, will be discussed in comparison to that observed for the (H(2)O)(14) supramolecular clusters in the case of the dinuclear complex [Mn(2)(cdaH)(2)(H(2)O)(4)]·4H(2)O [Ghosh et al. (2005). Inorg. Chem. 44, 3856-3862]. © 2012 International Union of Crystallography

Coordination polymers of 5-substituted isophthalic acid

DOE PAGES

McCormick, Laura J.; Morris, Samuel A.; Slawin, Alexandra M. Z.; ...

2015-12-10

In this work, the synthesis and characterisation of five coordination polymers - Ni 2(mip) 2 (H 2O) 8 ·2H 2O (1), Zn 6(mip) 5(OH) 2(H 2O) 4 ·7.4H 2O (2), Zn 6(mip) 5(OH) 2(H 2O) 2 ·4H 2O (3), Mn(HMeOip) 2 (4), and Mn 3(tbip) 2(Htbip) 2(EtOH) 2 (5) - are reported. Preliminary nitric oxide release data on compounds 2 and 3 are also given.

Molecular and polymeric uranyl and thorium hybrid materials featuring methyl substituted pyrazole dicarboxylates and heterocyclic 1,3-diketones

NASA Astrophysics Data System (ADS)

Carter, Korey P.; Kerr, Andrew T.; Taydakov, Ilya V.; Cahill, Christopher L.

2018-02-01

A series of seven novel f-element bearing hybrid materials have been prepared from either methyl substituted 3,4 and 4,5-pyrazoledicarboxylic acids, or heterocyclic 1,3- diketonate ligands using hydrothermal conditions. Compounds 1, [UO2(C6H4N2O4)2(H2O)], and 3, [Th(C6H4N2O4)4(H2O)5]·H2O feature 1-Methyl-1H-pyrazole-3,4-dicarboxylate ligands (SVI-COOH 3,4), whereas 2, [UO2(C6H4N2O4)2(H2O)], and 4, [Th(C6H5N2O4)(OH)(H2O)6]2·2(C6H5N2O4)·3H2O feature 1-Methyl-1H-pyrazole-4,5-dicarboxylate moieties (SVI-COOH 4,5). Compounds 5, [UO2(C13H15N4O2)2(H2O)]·2H2O and 6, [UO2(C11H11N4O2)2(H2O)]·4.5H2O feature 1,3-bis(4-N1-methyl-pyrazolyl)propane-1,3-dione and 1,3-bis(4-N1,3-dimethyl-pyrazolyl)propane-1,3-dione respectively, whereas the heterometallic 7, [UO2(C11H11N4O2)2(CuCl2)(H2O)]·2H2O is formed by using 6 as a metalloligand starting material. Single crystal X-ray diffraction indicates that all coordination to either [UO2]2+ or Th(IV) metal centers is through O-donation as anticipated. Room temperature, solid-state luminescence studies indicate characteristic uranyl emissive behavior for 1 and 2, whereas those for 5 and 6 are weak and poorly resolved.

Zwitterionic metal carboxylate complexes: In solid state

NASA Astrophysics Data System (ADS)

Nath, Bhaskar; Kalita, Dipjyoti; Baruah, Jubaraj B.

2012-07-01

A flexible dicarboxylic acid having composition [(CH(o-C5H4N)(p-C6H4OCH2CO2H)2] derived from corresponding bis-phenol reacts with various metal(II) acetates such as manganese(II), cobalt(II) and nickel(II) acetate leads to zwtterionic complexes with compositions [CH(o-C5H4N)(p-C6H4OCH2CO2){p-C6H4OCH2CO2M(H2O)5}].6H2O (where M = Mn, Co, Ni). The complexes are characterised by X-ray crystallography. These complexes have chiral center due to unsymmetric structure conferred to the ligand through coordination at only one carboxylate group of the ligand. In solid state these complexes are racemic.

The Synthesis and Characterization of Aromatic Hybrid Anderson–Evans POMs and their Serum Albumin Interactions: The Shift from Polar to Hydrophobic Interactions

PubMed Central

Al-Sayed, Emir; Blazevic, Amir; Roller, Alexander; Rompel, Annette

2015-01-01

Four aromatic hybrid Anderson polyoxomolybdates with Fe3+ or Mn3+ as the central heteroatom have been synthesized by using a pre-functionalization protocol and characterized by using single-crystal X-ray diffraction, FTIR, ESI-MS, 1H NMR spectroscopy, and elemental analysis. Structural analysis revealed the formation of (TBA)3[FeMo6O18{(OCH2)3CNHCOC6H5}2]⋅3.5 ACN (TBA-FeMo6-bzn; TBA=tetrabutylammonium, ACN=acetonitrile, bzn=TRIS-benzoic acid alkanolamide, TRIS–R=(HOCH2)3C–R)), (TBA)3[FeMo6O18{(OCH2)3CNHCOC8H7}2]⋅2.5 ACN (TBA-FeMo6-cin; cin=TRIS-cinnamic acid alkanolamide), (TBA)3[MnMo6O18{(OCH2)3CNHCOC6H5}2]⋅3.5 ACN (TBA-MnMo6-bzn), and (TBA)3[MnMo6O18{(OCH2)3CNHCOC8H7}2]⋅2.5 ACN (TBA-MnMo6-cin). To make these four compounds applicable in biological systems, an ion exchange was performed that gave the water-soluble (up to 80 mm) sodium salts Na3[FeMo6O18{(OCH2)3CNHCOC6H5}2] (Na-FeMo6-bzn), Na3[FeMo6O18{(OCH2)3CNHCOC8H7}2] (Na-FeMo6-cin), Na3[MnMo6O18{(OCH2)3CNHCOC6H5}2] (Na-MnMo6-bzn), and Na3[MnMo6O18{(OCH2)3CNHCOC8H7}2] (Na-MnMo6-cin). The hydrolytic stability of the sodium salts was examined by applying ESI-MS in the pH range of 4 to 9. Sodium dodecylsulfate–polyacrylamide gel electrophoresis (SDS-PAGE) showed that human and bovine serum albumin (HSA and BSA) remain intact in solutions that contain up to 100 equivalents of the sodium salts over more than 4 d at 20 °C. Tryptophan (Trp) fluorescence quenching was applied to study the interactions between the sodium salts and HSA and BSA at pH 5.5 and 7.4. The quenching constants were extracted by using Stern–Volmer analysis, which suggested the formation of a 1:1 POM–protein complex in all samples. It is suggested that the aromatic hybrid POM approaches subdomain IIA of HSA and exhibits hydrophobic interactions with its hydrophobic tails, whereas the Anderson core is stabilized through electrostatic interactions with polar amino acid side chains from, for example, subdomain IB. PMID:26527418

Optical and structural properties of Al-doped ZnO thin films by sol gel process.

PubMed

Jun, Min-Chul; Koh, Jung-Hyuk

2013-05-01

Transparent conducting oxide (TCO) materials with high transmittance and good electrical conductivity have been attracted much attention due to the development of electronic display and devices such as organic light emitting diodes (OLEDs), and dye-sensitized solar cells (DSSCs). Aluminum doped zinc oxide thin films (AZO) have been well known for their use as TCO materials due to its stability, cost-effectiveness, good optical transmittance and electrical properties. Especially, AZO thin film, which have low resistivity of 2-4 x 10(-4) omega x cm which is similar to that of ITO films with wide band gap semiconductors. The AZO thin films were deposited on glass substrates by sol-gel spin-coating process. As a starting material, zinc acetate dihydrate (Zn(CH3COO)2 x 2H2O) and aluminum chloride hexahydrate (AlCl3 6H2O) were used. 2-methoxyethanol and monoethanolamine (MEA) were used as solvent and stabilizer, respectively. After deposited, the films were preheated at 300 degrees C on a hotplate and post-heated at 650 degrees C for 1.5 hrs in the furnace. We have studied the structural and optical properties as a function of Al concentration (0-2.5 mol.%).

Electrochemical growth of controlled tip shapes of ZnO nanorod arrays on silicon substrate and enhanced photoluminescence emission from nanopyramid arrays compared with flat-head nanorods

NASA Astrophysics Data System (ADS)

Alimanesh, Mahmoud; Hassan, Z.; Zainal, Norzaini

2017-10-01

Zinc oxide (ZnO) nanorod arrays (NRAs) with different morphologies such as; perfect hexagon flat-head, pyramidal, compact pencil, nail-shaped, and high-compact ZnO nanorod thin films, were successfully grown on silicon substrates. These NRAs were formed on substrates using a simple low-temperature electrochemical method without adding any catalyst or template via the precursors of zinc nitrate hexahydrate [Zn(NO3)2·6H2O] and hexamethylenetetramine [HMT; C6H12N4] with an equal molar concentration of 0.025 mol/l. The morphologies of the ZnO nanorods (NRs) could be controlled and transformed successfully in to other morphologies by changing the growth conditions, such as; growth temperature and applied current density. Detailed structural investigations reveal that the synthesized various NRs are single crystalline with wurtzite hexagonal phase and preferentially grow along the c-axis direction. The room temperature photoluminescence spectra show that each spectrum consists of an ultraviolet (UV) band and a relative broad visible light emission and infrared emission peak. The enhanced light emission intensity at UV peak (∼375 nm) is observed significantly from ZnO nanopyramid (NP) arrays because of the conical shape of NP. The photoluminescence intensity of the UV peak from the NPs is found to be 1.5-17 times larger than those from the other various NRs.

Hydrogen peroxide generation in a model paediatric parenteral amino acid solution.

PubMed

Brawley, V; Bhatia, J; Karp, W B

1993-12-01

1. Parenteral amino acid solutions undergo photooxidation, which may be an important factor in total parenteral nutrition-associated hepatic dysfunction. Light-exposed parenteral solutions containing amino acids, in addition to vitamins and trace minerals, generate free radicals, which, in turn, may contribute to this type of injury. This study examined the characteristics of H2O2 production in a parenteral amino acid solution modelled on a commercially available paediatric parenteral amino acid solution. 2. The solution was exposed to light in the presence of riboflavin-5'-monophosphate (riboflavin), and peroxide formation in the presence and absence of catalase (H2O2 formation) was assayed using potassium iodide/molybdate. 3. Peak H2O2 production occurred at a light intensity of 8 microW cm-2 nm-1 in the 425-475 nm waveband and was linear to 2 h of light exposure. H2O2 production reached 500 mumol/l at 24 h. 4. H2O2 was directly related to a riboflavin concentration of up to 20 mumol/l and was maximal at 30 mumol/l. 5. H2O2 production was greatest in the amino acid/riboflavin solution at a pH of between 5 and 6. 6. Under the conditions of light exposure intensity, light exposure time, riboflavin concentration and pH found during the administration of parenteral nutrition in neonatal intensive care units, net H2O2 production occurs in solutions modelled on a paediatric parenteral amino acid preparation.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barkaoui, Sami; Haddaoui, Marwa; Dhaouadi, Hassouna, E-mail: dhaouadihassouna@yahoo.fr

Nanostructured tricobalt tetraoxide, Co{sub 3}O{sub 4}, was hydrothermally synthesized starting from cobalt dichloride hexahydrate (CoCl{sub 2}·6H{sub 2}O) and urea (H{sub 2}NCONH{sub 2}) as precursor and polyethylene glycol-400 (PEG-400) as a structure-directing agent. Uniform urchin-like nanostructures were hydrothermally obtained at 150 °C for 16 h, and the Co{sub 3}O{sub 4} morphology did not collapse after a subsequent calcination at 300 °C for 2 h. XRD measurements indicated that the average sizes of Co{sub 3}O{sub 4} particles prior and after heating at 300 °C are 64 and 44 nm, respectively. This material has been successfully used for the nanostructuration of screen-printed carbonmore » electrodes (SPCEs) which were used for the sensitive electrochemical detection of hydrogen peroxide (H{sub 2}O{sub 2}). The sensor is endowed with a large dynamic range (0.1 to 50 µM) and a limit of detection of 0.145 µM. The as obtained results show that the Co{sub 3}O{sub 4} nanomaterial could be a candidate to be used as sensors for the detection of analytes. - Graphical abstract: The nanowires appear to have a common center and grow to the outside along the radial direction. - Highlights: • Nanostructured was hydrothermally prepared using PEG-400. • Uniform urchin-like Co{sub 3}O{sub 4} nanostructures were hydrothermally obtained. • X-ray diffraction showed a cubic structure after calcinations process. • Nanostructured Co{sub 3}O{sub 4} was used for the sensitive electrochemical detection of H{sub 2}O{sub 2.} • The sensor is endowed with a large dynamic range 0.1 to 50 µM.« less

Can perchlorates be transformed to hydrogen peroxide (H2O2) products by cosmic rays on the Martian surface?

NASA Astrophysics Data System (ADS)

Crandall, Parker B.; Góbi, Sándor; Gillis-Davis, Jeffrey; Kaiser, Ralf I.

2017-09-01

Due to their oxidizing properties, perchlorates (ClO4-) are suggested by the planetary science community to play a vital role in the scarcity of organics on the Martian surface. However, alternative oxidation agents such as hydrogen peroxide (H2O2) have received surprisingly little attention. In this study, samples of magnesium perchlorate hexahydrate (Mg(ClO4)2 · 6H2O) were exposed to monoenergetic electrons and D2+ ions separately, sequentially, and simultaneously to probe the effects of galactic cosmic ray exposure of perchlorates and the potential incorporation of hydrogen (deuterium) into these minerals. The experiments were carried out under ultrahigh-vacuum conditions at 50 K, after which the samples were slowly heated to 300 K while the subliming products were monitored by a quadrupole mass spectrometer. In all cases, molecular oxygen (O2) was detected upon the onset of irradiation and also during the warmup phase. In case of a simultaneous D2+-electron exposure, deuterated water (D2O) and deuterium peroxide (D2O2) were also detected in the warmup phase, whereas only small amounts of D2O2 were found after an exclusive D2+ irradiation. These experiments yield the first data identifying hydrogen peroxide as a potential product in the interaction of cosmic rays with perchlorates in the Martian regolith revealing that perchlorates are capable of producing multiple oxidizing agents (O2 and D2O2) that may account for the destruction of organics on the Martian surface.

Orphenadrinium picrate picric acid

PubMed Central

Fun, Hoong-Kun; Hemamalini, Madhukar; Siddaraju, B. P.; Yathirajan, H. S.; Narayana, B.

2010-01-01

The asymmetric unit of the title compound N,N-dimethyl-2-[(2-methyl­phen­yl)phenyl­meth­oxy]ethanaminium picrate picric acid, C18H24NO+·C6H2N3O7 −·C6H3N3O7, contains one orphenadrinium cation, one picrate anion and one picric acid mol­ecule. In the orphenadrine cation, the two aromatic rings form a dihedral angle of 70.30 (7)°. There is an intra­molecular O—H⋯O hydrogen bond in the picric acid mol­ecule, which generates an S(6) ring motif. In the crystal structure, the orphenadrine cations, picrate anions and picric acid mol­ecules are connected by strong inter­molecular N—H⋯O hydrogen bonds, π⋯π inter­actions between the benzene rings of cations and anions [centroid–centroid distance = 3.5603 (9) Å] and weak C—H⋯O hydrogen bonds, forming a three-dimensional network. PMID:21580426

A family of silver(I) complexes built with 2-sulfoterephthalic acid monosodium salt and different aminopyridine ligands: Syntheses, structures and properties

NASA Astrophysics Data System (ADS)

Zhang, Jie; Tan, Gai-Xiu; Liu, Bao-Lin; Dai, Yu-Bei; Xu, Na; Wen, Wei-Fen; Cao, Chong; Xiao, Hong-Ping

2017-05-01

Five Ag(I) coordination complexes, namely, [Ag6(2-stp)2(3-methyl-2-apy)3·H2O]n (1), [Ag3(2-stp)(4-methyl-2-apy)3]n (2), [Na2Ag18(2-stp)4(2-Hstp)4(5-methyl-2-apy)16 (H2O)4·11H2O]n (3), Ag3(2-stp)(6-methy-2-apy)4·H2O (4), and [Ag6(2-stp)2(6-methyl-2-apy)8(H2O)2·H2O]n (5) (2-NaH2stp = 2-sulfoterephthalic acid monosodium salt, 3-methyl-2-apy = 3-methyl-2-aminopyridine, 4-methyl-2-apy = 4-methyl-2-aminopyridine, 5-methyl-2-apy = 5-methyl-2-aminopyridine, 6-methyl-2-apy = 6-methyl-2-aminopyridine), have been synthesized and structurally characterized. Complexes 1 and 2 show two-dimensional network. In complex 3, the adjacent Ag10 units are bridged by 5-methyl-2-apy ligands to form a 2D infinite undulated sheet. Adjacent 2D sheets are linked by coordinative bonds between carboxylic oxygen atoms and Na(I) ions to form a 3D coordination polymer. Complex 4 is a 0-D discrete trinuclear molecule, and the self-complementary the Osbnd H⋯O and Nsbnd H⋯O hydrogen bonds incorporating hydrogen bond motifs extend these molecules into a 2D supramolecular framework. Compound 5 exhibits 1D-chain structure. However, complex 5 shows 3D supramolecular structure results from the linkage of neighboring layers through a rich hydrogen-bonding between uncoordinated sulfonates, amino groups and coordinated carboxylates. The thermogravimetric analyses and photoluminescence of the complexes were also investigated.

Coordination chemistry of vitamin C. Part I. Interaction of L-ascorbic acid with alkaline earth metal ions in the crystalline solid and aqueous solution.

PubMed

Tajmir-Riahi, H A

1990-10-01

The interaction of L-ascorbic acid with alkaline earth metal ions has been investigated in aqueous solution at pH 6-7. The solid salts of the type Mg(L-ascorbate)2.4H2O, Ca(L-ascorbate)2.2H2O, Sr(L-ascorbate)2.2H2O and Ba(L-ascorbate)2.2H2O were isolated and characterized by means of 13C NMR and FT-IR spectroscopy. Spectroscopic and other evidence suggested that in aqueous solution, the binding of the alkaline earth metal ions is through the O-3 atom of the ascorbate anion, while in the solid state the binding of the Mg(II) is different from those of the other alkaline earth metal ion salts. The Mg(II) ion binds to the O-3, O-1 atom of the two ascorbate anions and to two H2O molecules, while the eight-coordination around the Ca(II), Sr(II), and Ba(II) ions would be completed by the coordination of three acid anions, through O-5, O-6 of the first, O-3, O-5, O-6 of the second and O-1 of the third anion as well as to two H2O molecules. The structural properties of the alkaline earth metal-ascorbate salts are different in the solid and aqueous solution.

Threefold interweaving of (4,4) nets built from R(10)10(58) rings inthe hydrogen-bonded adduct 1,4-diazabicyclo

PubMed

Burchell; Ferguson; Lough; Glidewell

2000-09-01

The 1:1 adduct of 1,4-diazabicyclo[2.2.2]octane and 5-hydroxyisophthalic acid is a salt, [H(C(6)H(12)N(2))](+). [HOC(6)H(3)(COOH)COO](-) or C(6)H(13)N(2)(+).C(8)H(5)O(5)(-). The ions are linked by three types of hydrogen bond, i.e. N-H.O, O-H.O and O-H.N, into continuous two-dimensional (4,4) nets built from a single type of R(10)(10)(58) ring. Six independent sheets of this type make up the structure and these are interwoven in sets of three.

Preparation of Carboxylato-Coordinated Titanium Alkoxides from Carboxylic Anhydrides: Alkoxido Group Transfer from Metal Atom to Carbonyl Group.

PubMed

Czakler, Matthias; Artner, Christine; Schubert, Ulrich

2012-07-01

Reaction of titanium(IV) isopropoxide, Ti(O i Pr) 4 , with an equimolar amount of phthalic anhydride resulted in the transfer of an isopropoxido group from the metal atom to one carbonyl group of the anhydride and coordination of the thus formed monoester to the titanium atom. One monoester ligand in Ti 2 (O i Pr) 6 (μ 2 -OOC-C 6 H 4 -COO i Pr)(η 1 -OOC-C 6 H 4 -COO i Pr)( i PrOH) is bridging and the other is η 1 -coordinated. When the reaction is performed in the presence of 1 mol-equiv. of acetic acid, the oxido cluster Ti 6 (μ 3 -O) 6 (O i Pr) 6 (μ 2 -OOC-C 6 H 4 -COO i Pr) 6 was instead obtained. The μ 3 -oxygen groups in the latter compound are due to esterification of acetic acid by the cleaved isopropyl alcohol.

Deviation between the chemistry of Ce(IV) and Pu(IV) and routes to ordered and disordered heterobimetallic 4f/5f and 5f/5f phosphonates.

PubMed

Diwu, Juan; Wang, Shuao; Good, Justin J; DiStefano, Victoria H; Albrecht-Schmitt, Thomas E

2011-06-06

The heterobimetallic actinide compound UO(2)Ce(H(2)O)[C(6)H(4)(PO(3)H)(2)](2)·H(2)O was prepared via the hydrothermal reaction of U(VI) and Ce(IV) in the presence of 1,2-phenylenediphosphonic acid. We demonstrate that this is a kinetic product that is not stable with respect to decomposition to the monometallic compounds. Similar reactions have been explored with U(VI) and Ce(III), resulting in the oxidation of Ce(III) to Ce(IV) and the formation of the Ce(IV) phosphonate, Ce[C(6)H(4)(PO(3)H)(PO(3)H(2))][C(6)H(4)(PO(3)H)(PO(3))]·2H(2)O, UO(2)Ce(H(2)O)[C(6)H(4)(PO(3)H)(2)](2)·H(2)O, and UO(2)[C(6)H(4)(PO(3)H)(2)](H(2)O)·H(2)O. In comparison, the reaction of U(VI) with Np(VI) only yields Np[C(6)H(4)(PO(3)H)(2)](2)·2H(2)O and aqueous U(VI), whereas the reaction of U(VI) with Pu(VI) yields the disordered U(VI)/Pu(VI) compound, (U(0.9)Pu(0.1))O(2)[C(6)H(4)(PO(3)H)(2)](H(2)O)·H(2)O, and the Pu(IV) phosphonate, Pu[C(6)H(4)(PO(3)H)(PO(3)H(2))][C(6)H(4)(PO(3)H)(PO(3))]·2H(2)O. The reactions of Ce(IV) with Np(VI) yield disordered heterobimetallic phosphonates with both M[C(6)H(4)(PO(3)H)(PO(3)H(2))][C(6)H(4)(PO(3)H)(PO(3))]·2H(2)O (M = Ce, Np) and M[C(6)H(4)(PO(3)H)(2)](2)·2H(2)O (M = Ce, Np) structures, as well as the Ce(IV) phosphonate Ce[C(6)H(4)(PO(3)H)(PO(3)H(2))][C(6)H(4)(PO(3)H)(PO(3))]·2H(2)O. Ce(IV) reacts with Pu(IV) to yield the Pu(VI) compound, PuO(2)[C(6)H(4)(PO(3)H)(2)](H(2)O)·3H(2)O, and a disordered heterobimetallic Pu(IV)/Ce(IV) compound with the M[C(6)H(4)(PO(3)H)(PO(3)H(2))][C(6)H(4)(PO(3)H)(PO(3))]·2H(2)O (M = Ce, Pu) structure. Mixtures of Np(VI) and Pu(VI) yield disordered heterobimetallic Np(IV)/Pu(IV) phosphonates with both the An[C(6)H(4)(PO(3)H)(PO(3)H(2))][C(6)H(4)(PO(3)H)(PO(3))]·2H(2)O (M = Np, Pu) and An[C(6)H(4)(PO(3)H)(2)](2)·2H(2)O (M = Np, Pu) formulas. © 2011 American Chemical Society

Bright Stuff on Ceres = Sulfates and Carbonates on CI Chondrites

NASA Technical Reports Server (NTRS)

Zolensky, Michael; Chan, Queenie H. S.; Gounelle, Matthieu; Fries, Marc

2016-01-01

Recent reports of the DAWN spacecraft's observations of the surface of Ceres indicate that there are bright areas, which can be explained by large amounts of the Mg sulfate hexahydrate (MgSO4•6(H2O)), although the identification appears tenuous. There are preliminary indications that water is being evolved from these bright areas, and some have inferred that these might be sites of contemporary hydro-volcanism. A heat source for such modern activity is not obvious, given the small size of Ceres, lack of any tidal forces from nearby giant planets, probable age and presumed bulk composition. We contend that observations of chondritic materials in the lab shed light on the nature of the bright spots on Ceres

Phthalazin-1(2H)-one–picric acid (1/1)

PubMed Central

Yathirajan, H. S.; Narayana, B.; Swamy, M. T.; Sarojini, B. K.; Bolte, Michael

2008-01-01

The geometric parameters of the title compound, C8H6N2O·C6H3N3O7, are in the usual ranges. The three nitro groups are almost coplanar with the aromatic picrate ring [dihedral angles 10.2 (2)°, 7.62 (16) and 8.08 (17)°]. The mol­ecular conformation of the picric acid is stabilized by an intra­molecular O—H⋯O hydrogen bond. The phthalazin-1(2H)-one mol­ecules are connected via N—H⋯O hydrogen bonds, forming centrosymmetric dimers. PMID:21200682

The Synthesis and Characterization of Aromatic Hybrid Anderson-Evans POMs and their Serum Albumin Interactions: The Shift from Polar to Hydrophobic Interactions.

PubMed

Al-Sayed, Emir; Blazevic, Amir; Roller, Alexander; Rompel, Annette

2015-12-01

Four aromatic hybrid Anderson polyoxomolybdates with Fe(3+) or Mn(3+) as the central heteroatom have been synthesized by using a pre-functionalization protocol and characterized by using single-crystal X-ray diffraction, FTIR, ESI-MS, (1) H NMR spectroscopy, and elemental analysis. Structural analysis revealed the formation of (TBA)3 [FeMo6 O18 {(OCH2 )3 CNHCOC6 H5 }2 ]⋅3.5 ACN (TBA-FeMo6 -bzn; TBA=tetrabutylammonium, ACN=acetonitrile, bzn=TRIS-benzoic acid alkanolamide, TRISR=(HOCH2 )3 CR)), (TBA)3 [FeMo6 O18 {(OCH2 )3 CNHCOC8 H7 }2 ]⋅2.5 ACN (TBA-FeMo6 -cin; cin=TRIS-cinnamic acid alkanolamide), (TBA)3 [MnMo6 O18 {(OCH2 )3 CNHCOC6 H5 }2 ]⋅3.5 ACN (TBA-MnMo6 -bzn), and (TBA)3 [MnMo6 O18 {(OCH2 )3 CNHCOC8 H7 }2 ]⋅2.5 ACN (TBA-MnMo6 -cin). To make these four compounds applicable in biological systems, an ion exchange was performed that gave the water-soluble (up to 80 mM) sodium salts Na3 [FeMo6 O18 {(OCH2 )3 CNHCOC6 H5 }2 ] (Na-FeMo6 -bzn), Na3 [FeMo6 O18 {(OCH2 )3 CNHCOC8 H7 }2 ] (Na-FeMo6 -cin), Na3 [MnMo6 O18 {(OCH2 )3 CNHCOC6 H5 }2 ] (Na-MnMo6 -bzn), and Na3 [MnMo6 O18 {(OCH2 )3 CNHCOC8 H7 }2 ] (Na-MnMo6 -cin). The hydrolytic stability of the sodium salts was examined by applying ESI-MS in the pH range of 4 to 9. Sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that human and bovine serum albumin (HSA and BSA) remain intact in solutions that contain up to 100 equivalents of the sodium salts over more than 4 d at 20 °C. Tryptophan (Trp) fluorescence quenching was applied to study the interactions between the sodium salts and HSA and BSA at pH 5.5 and 7.4. The quenching constants were extracted by using Stern-Volmer analysis, which suggested the formation of a 1:1 POM-protein complex in all samples. It is suggested that the aromatic hybrid POM approaches subdomain IIA of HSA and exhibits hydrophobic interactions with its hydrophobic tails, whereas the Anderson core is stabilized through electrostatic interactions with polar amino acid side chains from, for example, subdomain IB. © 2015 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Evaluation of lactic acid as an initial and secondary subprimal intervention for Escherichia coli O157:H7, non-O157 Shiga toxin-producing E. coli, and a nonpathogenic E. coli surrogate for E. coli O157:H7.

PubMed

Pittman, C I; Geornaras, I; Woerner, D R; Nightingale, K K; Sofos, J N; Goodridge, L; Belk, K E

2012-09-01

Lactic acid can reduce microbial contamination on beef carcass surfaces when used as a food safety intervention, but effectiveness when applied to the surface of chilled beef subprimal sections is not well documented. Studies characterizing bacterial reduction on subprimals after lactic acid treatment would be useful for validations of hazard analysis critical control point (HACCP) systems. The objective of this study was to validate initial use of lactic acid as a subprimal intervention during beef fabrication followed by a secondary application to vacuum-packaged product that was applied at industry operating parameters. Chilled beef subprimal sections (100 cm(2)) were either left uninoculated or were inoculated with 6 log CFU/cm(2) of a 5-strain mixture of Escherichia coli O157:H7, a 12-strain mixture of non-O157 Shiga toxin-producing E. coli (STEC), or a 5-strain mixture of nonpathogenic (biotype I) E. coli that are considered surrogates for E. coli O157:H7. Uninoculated and inoculated subprimal sections received only an initial or an initial and a second "rework" application of lactic acid in a custombuilt spray cabinet at 1 of 16 application parameters. After the initial spray, total inoculum counts were reduced from 6.0 log CFU/cm(2) to 3.6, 4.4, and 4.4 log CFU/cm(2) for the E. coli surrogates, E. coli O157:H7, and non-O157 STEC inoculation groups, respectively. After the second (rework) application, total inoculum counts were 2.6, 3.2, and 3.6 log CFU/cm(2) for the E. coli surrogates, E. coli O157:H7, and non-O157 STEC inoculation groups, respectively. Both the initial and secondary lactic acid treatments effectively reduced counts of pathogenic and nonpathogenic strains of E. coli and natural microflora on beef subprimals. These data will be useful to the meat industry as part of the HACCP validation process.

Synthesis and structure of tetranuclear orthometallated Pd(II) complexes derived from bis-iminophosphoranes.

PubMed

Bielsa, Raquel; Navarro, Rafael; Soler, Tatiana; Urriolabeitia, Esteban P

2008-04-07

The reaction of Pd(OAc)2 with bis-iminophosphoranes Ph3P=NCH2CH2CH2N=PPh3 (1a), [C6H4(C(O)N=PPh3)2-1,3] (1b) and [C6H4(C(O)N=PPh3)2-1,2] (1c), gives the orthopalladated tetranuclear complexes [{Pd(mu-Cl){C6H4(PPh2=NCH2-kappa-C,N)-2}}2CH2]2 (2a) [{Pd(mu-OAc){C6H4(PPh2=NC(O)-kappa-C,N)-2}}2C6H4-1',3']2 (2b) and [{Pd(mu-OAc){C6H4(PPh2=NC(O)-kappa-C,N)-2}}2C6H4-1',2']2 (2c). The reaction takes place in CH2Cl2 for 1a, but must be performed in glacial acetic acid for 1b and 1c. The process implies in all cases the activation of a C-H bond on a Ph ring of the phosphonium group, with concomitant formation of endo complexes. This is the expected behaviour for 1a, but for 1b and 1c reverses the exo orientation observed in other ketostabilized iminophosphoranes. The influence of the solvent in the orientation of the reaction is discussed. The dinuclear acetylacetonate complexes [{Pd(acac-O,O'){C6H4(PPh2=NCH2-kappa-C,N)-2}}2CH2] (3a), [{Pd(acac-O,O'){C6H4(PPh2=NC(O)-kappa-C,N)-2}}2C6H4-1',3'] (3b) and [{Pd(acac-O,O'){C6H4(PPh2=NC(O)-kappa-C,N)-2}}2C6H4-1',2'] (3c) have been obtained from the halide-bridging tetranuclear derivatives. The X-ray crystal structure of [3c.4CHCl3] is also reported.

Tetranuclear copper(II) complexes bridged by alpha-D-glucose-1-phosphate and incorporation of sugar acids through the Cu4 core structural changes.

PubMed

Kato, Merii; Sah, Ajay Kumar; Tanase, Tomoaki; Mikuriya, Masahiro

2006-08-21

Tetranuclear copper(II) complexes containing alpha-D-glucose-1-phosphate (alpha-D-Glc-1P), [Cu4(mu-OH){mu-(alpha-D-Glc-1P)}2(bpy)4(H2O)2]X3 [X = NO3 (1a), Cl (1b), Br (1c)], and [Cu4(mu-OH){mu-(alpha-D-Glc-1P)}2(phen)4(H2O)2](NO3)3 (2) were prepared by reacting the copper(II) salt with Na2[alpha-D-Glc-1P] in the presence of diimine ancillary ligands, and the structure of 2 was characterized by X-ray crystallography to comprise four {Cu(phen)}2+ fragments connected by the two sugar phosphate dianions in 1,3-O,O' and 1,1-O mu4-bridging fashion as well as a mu-hydroxo anion. The crystal structure of 2 involves two chemically independent complex cations in which the C2 enantiomeric structure for the trapezoidal tetracopper(II) framework is switched according to the orientation of the alpha-D-glucopyranosyl moieties. Temperature-dependent magnetic susceptibility data of 1a indicated that antiferromagnetic spin coupling is operative between the two metal ions joined by the hydroxo bridge (J = -52 cm(-1)) while antiferromagnetic interaction through the Cu-O-Cu sugar phosphate bridges is weak (J = -13 cm(-1)). Complex 1a readily reacted with carboxylic acids to afford the tetranuclear copper(II) complexes, [Cu4{mu-(alpha-D-Glc-1P)}2(mu-CA)2(bpy)4](NO3)2 [CA = CH3COO (3), o-C6H4(COO)(COOH) (4)]. Reactions with m-phenylenediacetic acid [m-C6H4(CH2COOH)2] also gave the discrete tetracopper(II) cationic complex [Cu4{mu-(alpha-D-Glc-1P)}2(mu-m-C6H4(CH2COO)(CH2COOH))2(bpy)4](NO3)2 (5a) as well as the cluster polymer formulated as {[Cu4{mu-(alpha-D-Glc-1P)}2(mu-m-C6H4(CH2COO)2)(bpy)4](NO3)2}n (5b). The tetracopper structure of 1a is converted into a symmetrical rectangular core in complexes 3, 4, and 5b, where the hydroxo bridge is dissociated and, instead, two carboxylate anions bridge another pair of Cu(II) ions in a 1,1-O monodentate fashion. The similar reactions were applied to incorporate sugar acids onto the tetranuclear copper(II) centers. Reactions of 1a with delta-D-gluconolactone, D-glucuronic acid, or D-glucaric acid in dimethylformamide resulted in the formation of discrete tetracopper complexes with sugar acids, [Cu4{mu-(alpha-D-Glc-1P)}2(mu-SA)2(bpy)4](NO3)2 [SA = D-gluconate (6), D-glucuronate (7), D-glucarateH (8a)]. The structures of 6 and 7 were determined by X-ray crystallography to be almost identical with that of 3 with additional chelating coordination of the C-2 hydroxyl group of D-gluconate moieties (6) or the C-5 cyclic O atom of D-glucuronate units (7). Those with D-glucaric acid and D-lactobionic acid afforded chiral one-dimensional polymers, {[Cu4{mu-(alpha-D-Glc-1P)}2(mu-D-glucarate)(bpy)4](NO3)2}n (8b) and {[Cu4{mu-(alpha-D-Glc-1P)}2(mu-D-lactobionate)(bpy)4(H2O)2](NO3)3}n (9), respectively, in which the D-Glc-1P-bridged tetracopper(II) units are connected by sugar acid moieties through the C-1 and C-6 carboxylate O atoms in 8b and the C-1 carboxylate and C-6 alkoxy O atoms of the gluconate chain in 9. When complex 7 containing d-glucuronate moieties was heated in water, the mononuclear copper(II) complex with 2-dihydroxy malonate, [Cu(mu-O2CC(OH)2CO2)(bpy)] (10), and the dicopper(II) complex with oxalate, [Cu2(mu-C2O4)(bpy)2(H2O)2](NO3)2 (11), were obtained as a result of oxidative degradation of the carbohydrates through C-C bond cleavage reactions.

Structurally characterized 1,1,3,3-tetramethylguanidine solvated magnesium aryloxide complexes: [Mg(mu-OEt)(DBP)(H-TMG)]2, [Mg(mu-OBc)(DBP)(H-TMG)]2, [Mg(mu-TMBA)(DBP)(H-TMG)]2, [Mg(mu-DPP)(DBP)(H-TMG)]2, [Mg(BMP)2(H-TMG)2], [Mg(O-2,6-Ph2C6H3)2 (H-TMG)2].

PubMed

Monegan, Jessie D; Bunge, Scott D

2009-04-06

The synthesis and structural characterization of several 1,1,3,3-tetramethylguanidine (H-TMG) solvated magnesium aryloxide complexes are reported. Bu(2)Mg was successfully reacted with H-TMG, HOC(6)H(3)(CMe(3))(2)-2,6 (H-DBP), and either ethanol, a carboxylic acid, or diphenyl phosphate in a 1:1 ratio to yield the corresponding [Mg(mu-L)(DBP)(H-TMG)](2) where L = OCH(2)CH(3) (OEt, 1), O(2)CC(CH(3))(3) (OBc, 2), O(2)C(C(6)H(2)-2,4,6-(CH(3))(3)) (TMBA, 3), or O(2)P(OC(6)H(5))(2) (DPP, 4). Bu(2)Mg was also reacted with two equivalents of H-TMG and HOC(6)H(3)(CMe(3))-2-(CH(3))-6 (BMP) or HO-2,6-Ph(2)C(6)H(3) to yield [Mg(BMP)(2)(H-TMG)(2)] (5) and [Mg(O-2,6-Ph(2)C(6)H(3))(2)(H-TMG)(2)] (6). Compounds 1-6 were characterized by single-crystal X-ray diffraction. Polymerization of l- and rac-lactide with 1 was found to generate polylactide (PLA). A discussion concerning the relevance of compounds 2 - 4 to the structure of Mg-activated phosphatase enzymes is also provided. The bulk powders for all complexes were found to be in agreement with the crystal structures based on elemental analyses, FT-IR spectroscopy, and (1)H, (13)C and (31)P NMR studies.

Synthesis, characterization, X-ray crystal structure, DFT calculation and antibacterial activities of new vanadium(IV, V) complexes containing chelidamic acid and novel thiourea derivatives.

PubMed

Farzanfar, Javad; Ghasemi, Khaled; Rezvani, Ali Reza; Delarami, Hojat Samareh; Ebrahimi, Ali; Hosseinpoor, Hona; Eskandari, Amir; Rudbari, Hadi Amiri; Bruno, Giuseppe

2015-06-01

Three new thiourea ligands derived from the condensation of aroyl- and aryl-isothiocyanate derivatives with 2,6-diaminopyridine, named 1,1'-(pyridine-2,6-diyl)bis(3-(benzoyl)thiourea) (L1), 1,1'-(pyridine-2,6-diyl)bis(3-(2-chlorobenzoyl)thiourea) (L2) and 1,1'-(pyridine-2,6-diyl)bis(3-(4-chlorophenyl)thiourea) (L3), their oxido-vanadium(IV) complexes, namely [VO(L1('))(H2O)] (C1), [VO(L2('))(H2O)] (C2) and [VO(L3('))(H2O)] (C3), and also, dioxo-vanadium(V) complex containing 4-hydroxy-2,6-pyridine dicarboxylic acid (chelidamic acid, H2dipic-OH) and metformin (N,N-dimethylbiguanide, Met), named [H2Met][VO2(dipic-OH)]2·H2O (C4), were synthesized and characterized by elemental analysis, FTIR and (1)H NMR and UV-visible spectroscopies. Proposed structures for free thiourea ligands and their vanadium complexes were corroborated by applying geometry optimization and conformational analysis. Solid state structure of complex [H2Met][VO2(dipic-OH)]2·H2O (triclinic, Pī) was fully determined by single crystal X-ray diffraction analysis. In this complex, metformin is double protonated and acted as counter ion. The antibacterial properties of these compounds were investigated in vitro against standard Gram-positive and Gram-negative bacterial strains. The experiments showed that vanadium(IV) complexes had the superior antibacterial activities than novel thiourea derivatives and vanadium(V) complex against all Gram-positive and Gram-negative bacterial strains. Copyright © 2015 Elsevier Inc. All rights reserved.

Cuboid Ni2 P as a Bifunctional Catalyst for Efficient Hydrogen Generation from Hydrolysis of Ammonia Borane and Electrocatalytic Hydrogen Evolution.

PubMed

Du, Yeshuang; Liu, Chao; Cheng, Gongzhen; Luo, Wei

2017-11-16

The design of high-performance catalysts for hydrogen generation is highly desirable for the upcoming hydrogen economy. Herein, we report the colloidal synthesis of nanocuboid Ni 2 P by the thermal decomposition of nickel chloride hexahydrate (NiCl 2 ⋅6 H 2 O) and trioctylphosphine. The obtained nanocuboid Ni 2 P was characterized by using powder X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and inductively coupled plasma atomic emission spectroscopy. For the first time, the as-synthesized nanocuboid Ni 2 P is used as a bifunctional catalyst for hydrogen generation from the hydrolysis of ammonia borane and electrocatalytic hydrogen evolution. Owing to the strong synergistic electronic effect between Ni and P, the as-synthesized Ni 2 P exhibits catalytic performance that is superior to its counterpart without P doping. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Assembly of three organic-inorganic hybrid supramolecular materials based on reduced molybdenum(V) phosphates

NASA Astrophysics Data System (ADS)

Zhang, He; Yu, Kai; Lv, Jing-Hua; Wang, Chun-Mei; Wang, Chun-Xiao; Zhou, Bai-Bin

2014-09-01

Three supramolecular materials based on {P4Mo6} polyoxoanions, (Hbbi)2(H2bbi)[Cu3Mo12VO24(OH)6(H2O)6(HPO4)4(H2PO4)2(PO4)2]·3H2O (1), (Hbbi)2(H2bbi)[Ni3Mo12VO24(OH)6(H2O)2(HPO4)4(H2PO4)2(PO4)2]·9H2O (2), (Hbpy)(bpy)3[Ni2(H2O)10Na(PCA)2][NiMo12VO24(OH)6(H2PO4)6(PO4)2]·6H2O (3) (bbi=1,1‧-(1,4-butanediyl)bis(imidazole), bpy=4,4‧-bipyridine, PCA=pyridine-4-carboxylic acid), have been hydrothermally synthesized and structurally characterized by the elemental analysis, TG, IR, UV-vis, PXRD and the single-crystal X-ray diffraction. Compounds 1 and 2 exhibit covalent 1-D chains constructed from M[P4Mo6]2 dimeric cluster and {M(H2O)n} (M=Cu, n=3 for 1 and M=Ni, n=1 for 2) linker. Compound 3 possesses an unusual POMMOF supramolecular layers based on [Ni(P4Mo6)]2 dimeric units and 1-D metal-organic strings [Ni(H2O)5Na(PCA)]n, in which an in situ ligand of PCA from 1,3-bis(4-pyridyl)propane (bpp) precursor was observed. Furthermore, the electrochemical behavior of 1-3-CPE and magnetic properties of 1-3 have been investigated in detail.

Structure and magnetism of a Mn(III)-Mn(II)-Mn(II)-Mn(III) chain complex.

PubMed

Uhrecký, Róbert; Moncoľ, Ján; Koman, Marian; Titiš, Ján; Boča, Roman

2013-07-14

A novel tetranuclear manganese(II/III) complex with anions of pyridine-2,6-dicarboxylic acid (dipicolinic acid) has been synthesised and magneto-structurally characterised. The crystal structure of [Mn(II)2Mn(III)2(dipic)6(H2O)4]·2CH3OH·4H2O has been determined by single-crystal X-ray diffraction. The tetranuclear complex molecule [Mn(II)2Mn(III)2(dipic)6(H2O)4] is centrosymmetric and two manganese(II) and two manganese(III) atoms are bridged by four dipicolinate ligands. The complex molecules and uncoordinated water and methanol molecules are connected through hydrogen bonds and they form a 3D supramolecular hydrogen-bonding network.

Nano-Structured Magnesium Oxide Coated Iron Ore: Its Application to the Remediation of Wastewater Containing Lead.

PubMed

Nagarajah, Ranjini; Jang, Min; Pichiah, Saravanan; Cho, Jongman; Snyder, Shane A

2015-12-01

Magnetically separable nano-structured magnesium oxide coated iron ore (IO(MgO)) was prepared using environmentally benign chemicals, such as iron ore (IO), magnesium(II) nitrate hexahydrate [Mg(NO3)2 x 6H2O] and urea; via an easy and fast preparation method. The lO(MgO) was characterized using X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS) and alternating gradient magnetometer (AGM) analyses. The isotherm and kinetic studies indicated that lO(MgO) has a comparably higher Langmuir constant (K(L), 1.69 L mg(-1)) and maximum sorption capacity (33.9 mg g(-1)) for lead (Pb) than other inorganic media. Based on MgO amount, the removal capacity of Pb by IO(MgO) was 2,724 mg Pb (g MgO)(-1), which was higher than that (1,980 mg g(-1)) for flowerlike magnesium oxide nanostructures reported by Cao et al. The kinetics, FE-SEM, elemental mapping and XRD results revealed that the substitution followed by precipitation was identified as the mechanism of Pb removal and plumbophyllite (Pb2Si4O10 x H2O) was the precipitated phase of Pb. A leaching test revealed that IOMgO) had negligible concentrations of leached Fe at pH 4-9. Since the base material, IO, is cheap and easily available, lO(MgO) could be produced in massive amounts and used for remediation of wastewater containing heavy metals, applying simple and fast magnetic separation.

Gabapentinium picrate.

PubMed

Li, Hongqi; Yathirajan, H S; Mallesha, L; Mohana, K N; Narayana, B

2009-03-19

The title compound {systematic name: [1-(carboxy-meth-yl)cyclo-hexyl]methanaminium 2,4,6-trinitro-phenolate}, C(9)H(18)NO(2) (+)·C(6)H(2)N(3)O(7) (-), was synthesized from picric acid and gabapentin. The crystal packing is stabilized by intra-molecular N-H⋯O=N and N-H⋯O-Ph hydrogen bonds. An O-H⋯O inter-action is also present.

Polyoxomolybdates functionalized by a flexible carboxylic acid and their photochromic properties

NASA Astrophysics Data System (ADS)

Wang, Jin; Ma, Pengtao; Wang, Yaping; Zhang, Dongdi; Niu, Jingyang; Wang, Jingping

2017-11-01

Two inorganic-organic hybridized polyoxomolybdates, Cs8NaH [(SeMo6O21)C6H3O3(CH2CO2)3]2·10H2O (1) and Cs8H4 [(AsMo6O21)C6H3O3(CH2CO2)3]2·10H2O (2), functionalized by a flexible tri-podal multicarboxylic ligand 1,3,5-tris (carboxymethoxy)benzene (TCMB) have been synthesized and characterized. Single-crystal X-ray diffraction analysis reveals that each of the two hybrids consists of two {XMo6} (X = Se, As) units supported by two TCMB molecules. The photochromism and thermochromism behaviors of the two compounds have been explored. The color of compound 2 could change dramatically from white to black within just 1 min of irradiation by a Xe lamp. During thermochromic experiments the two compounds change their color at 423 K for 1 and 393 K for 2, respectively.

Two isomorphous Co(ii) coordination polymers based on new α,α-disubstituted derivatives of zoledronic acid: synthesis, structures and properties.

PubMed

Rojek, Tomasz; Goldeman, Waldemar; Slepokura, Katarzyna; Duczmal, Marek; Wojciechowska, Agnieszka; Matczak-Jon, Ewa

2017-05-30

Two novel α,α-disubstituted derivatives of zoledronic acid, namely 1-hydroxy-2-(1H-imidazol-1-yl)-2-methylpropylidene-1,1-diphosphonic acid (H 4 L1) and 1-hydroxy-2-[1-(1H-imidazol-1-yl)cyclopropyl]ethylidene-1,1-diphosphonic acid (H 4 L2) were synthesized and structurally characterized by single-crystal X-ray diffraction. The reaction of cobalt acetate with H 4 L1 and H 4 L2 carried out under hydrothermal conditions afforded two isomorphous Co 3 (HL1) 2 (H 2 O) 6 ·6H 2 O (1a) and Co 3 (HL2) 2 (H 2 O) 6 ·6H 2 O (2a) complexes. Both compounds are characterized by means of X-ray crystallography, IR and NIR-Vis-UV spectroscopic methods. Furthermore, their magnetic properties and thermal stabilities are reported. The crystals of 1a and 2a feature infinite 1D polymeric chains built from alternately arranged dinuclear [Co2(HL1/HL2)(H 2 O) 2 ] 2 units and {Co1O 6 } octahedra running along the [1[combining macron]10] crystallographic direction. In both compounds, crystallographically distinct Co1 and Co2 atoms are six-coordinated. As is reflected in T values (T - index of tetragonality), the coordination environment of Co1 generates a slightly elongated octahedron (T = 0.94), whereas a slightly compressed octahedron (T = 1.06 for 1a and 1.05 for 2a) is formed around Co2. An assumption that the d-d type absorption is mainly attributed to the inversion related Co2 centers, whose population is two times higher than that of Co1, afforded a good correlation between calculated transition energies and experimental NIR-Vis-UV spectra. The magnetic susceptibility measurements analyzed in terms of a spin-3/2 Heisenberg trimer chain revealed that Co1Co2 interactions within the trimer are antiferromagnetic whereas Co2Co2 intertrimer interactions are ferromagnetic.

One-pot Synthesis and Surface Modification of Fe3O4 Nanoparticles Using Polyvinyl Alcohol by Coprecipitation and Ultrasonication Methods

NASA Astrophysics Data System (ADS)

Nugraha, Aditya D.; Wulandari, Ika O.; Hutami Rahayu, L. B.; Riva'i, Imam; Santojo, D. J. Djoko H.; Sabarudin, Akhmad

2018-01-01

Among the various substances developed through nanoparticles, iron oxide (Fe3O4) nanoparticle is one of the substances that have been widely used in various fields such as industry, agriculture, biotechnology and biomedicine. The synthesis of Fe3O4 nanoparticle can be carried out by two methods, consist of chemical and mechanical synthesis methods. Coprecipitation is one of the most commonly used methods for chemical synthesis. Fe3O4 compounds are easily oxidized because they are amphoteric. To avoid the continuous oxidation process, chemical modification process should be carried out with the addition of a solution of polyvinyl alcohol (PVA). In this study, PVA-coated Fe3O4 nanoparticles were synthesized by in-situ coprecipitation and ultrasonication methods through direct mixing (one-pot synthesis) of the iron (II) chloride tetrahydrate (FeCl2.4H2O), iron (III) chloride hexahydrate (FeCl3.6H2O), and PVA under alkaline condition. The effects of addition amount of NH3solution (by adjusting its flow rate using automated syringe pump) and PVA concentration were gently studied. Interaction of PVA with Fe3O4 nanoparticle was identified by infrared spectroscopy whereas lattice parameters and crystallite sizes of the synthesized Fe3O4 nanoparticles and PVA-coated Fe3O4 nanoparticles were assessed by X-ray diffraction (XRD).

Supramolecular hydrogen-bonding networks in bis(adeninium) phthalate phthalic acid 1.45-hydrate.

PubMed

Sridhar, Balasubramanian; Ravikumar, Krishnan

2007-04-01

In the title compound, 2C(5)H(6)N(5)(+).C(8)H(4)O(4)(2-).C(8)H(6)O(4).1.45H(2)O, the asymmetric unit comprises two adeninium cations, two half phthalate anions with crystallographic C(2) symmetry, one neutral phthalic acid molecule, and one fully occupied and one partially occupied site (0.45) for water molecules. The adeninium cations form N-H...O hydrogen bonds with the phthalate anions. The cations also form infinite one-dimensional polymeric ribbons via N-H...N interactions. In the crystal packing, hydrogen-bonded columns of cations, anions and phthalate anions extend parallel to the c axis. The water molecules crosslink adjacent columns into hydrogen-bonded layers.

Reaction Mechanisms of Magnesium Potassium Phosphate Cement and its Application

NASA Astrophysics Data System (ADS)

Qiao, Fei

Magnesium potassium phosphate cement (MKPC) is a kind of cementitious binder in which the chemical bond is formed via a heterogeneous acid-base reaction between dead burned magnesia powder and potassium phosphate solution at room temperature. Small amount of boron compounds can be incorporated in the cement as a setting retarder. The final reaction product of MgO-KH2PO4-H 2O ternary system is identified as magnesium potassium phosphate hexahydrate, MgKPO4·6H2O. However, the mechanisms and procedures through which this crystalline product is formed and the conditions under which the crystallization process would be influenced are not yet clear. Understanding of the reaction mechanism of the system is helpful for developing new methodologies to control the rapid reaction process and furthermore, to adjust the phase assemblage of the binder, and to enhance the macroscopic properties. This study is mainly focused on the examination of the reaction mechanism of MKPC. In addition, the formulation optimization, microstructure characterization and field application in rapid repair are also systematically studied. The chemical reactions between magnesia and potassium dihydrogen phosphate are essentially an acid-base reaction with strong heat release, the pH and temperature variation throughout the reaction process could provide useful information to disclose the different stages in the reaction. However, it would be very difficult to conduct such tests on the cement paste due to the limited water content and fast setting. In the current research, the reaction mechanism of MKPC is investigated on the diluted MKPC system through monitoring the pH and temperature development, identification of the solid phase formed, and measurement of the ionic concentration of the solution. The reaction process can be explained as follows: when magnesia and potassium phosphate powder are mixed with water, phosphate is readily dissolved, which is instantly followed by the dissociation of magnesia. With the increase of magnesium ions in the solution, MgHPO4·7H2O is the first product precipitated, and its crystallization is accompanied with the increase of both pH and temperature. Beyond pH of 7, MgHPO4·7H 2O is transformed to Mg2KH(PO4)2·15H 2O, leading to a slight decrease of pH. The following dramatic increase of pH may be due to the formation of Mg2KH(PO4) 2·15H2O. Finally, Mg2KH(PO4) 2·15H2O gradually transforms to MgKPO4·6H 2O and leads to the second decrease of pH. Both increasing molar ratio of magnesium to phosphate (M/P) and decreasing the weight ratio of liquid to solid can speed up the reaction rate while addition of small amount of boron compounds can prolong the process even though the products are not changed. The retarding mechanism of boron compounds is related to their buffering effect on the pH of the solution, i.e. decreasing pH development rate, leads to delaying the formation of reaction products. The performance of MKPC based cementitious materials can be significantly influenced by M/P molar ratio, addition of setting retarder, water content, fly ash replacement of magnesia and aggregate usage. Therefore, the formulation of MKPC based materials is optimized in terms of workability, compressive strength, and cost consideration. With optimized formulation, MKPC mortars show high early compressive and flexural strength, superior bond strength to ordinary Portland cement mortar/concrete substrate, and low drying shrinkage. Undoubtedly, the mechanical properties of this cement is closely related to its inner composition and microstructure. The microstructure examination shows that the phase assemblage and the morphology characteristics of MKPC paste vary with the different formulae. In the formulation with lower M/P ratio of 2, KH2PO4 residues can be found in a flat, smooth, and bulky mass form. The reaction product MgKPO4·6H2O, can be observed as acicular crystal habit with large aspect ratio of 30. With the increase of M/P ratio, MgKPO4·6H2O is crystallized in a larger size and the morphology is changed from acicular to bladed and then prismatic shape. The magnesia residues can be well identified in all of the formulations.

Highly efficient electrochemiluminescence on microporous MOFs containing zinc secondary building units with a pcu net

NASA Astrophysics Data System (ADS)

Feng, Chao; Zhao, Hong; Li, Zong-Qun

2018-02-01

Two 3D microporous MOFs, [Zn4(μ4-O)(μ4-pzca)3]n (1) and {[Zn2(pzca)2(4, 4'-bipy)]·2H2O}n (2) (H2pzca=1H-pyrazole-4-carboxylic acid) were synthesized. The X-ray data reveals that the 1 contains [Zn4(μ4-O)(CO2)6] and [Zn4(μ4-O)(N2)6] SBUs, the 2 contains Zn2N6O2 SBUs. Furthermore, MOFs 1 and 2 have a same topology pcu net. Interestingly MOF 1 exhibits good ECL (electrochemiluminescence) behavior.

Crystal structures of hibiscus acid and hibiscus acid dimethyl ester isolated from Hibiscus sabdariffa (Malvaceae).

PubMed

Zheoat, Ahmed M; Gray, Alexander I; Igoli, John O; Kennedy, Alan R; Ferro, Valerie A

2017-09-01

The biologically active title compounds have been isolated from Hibiscus sabdariffa plants, hibiscus acid as a dimethyl sulfoxide monosolvate [systematic name: (2 S ,3 R )-3-hy-droxy-5-oxo-2,3,4,5-tetra-hydro-furan-2,3-di-carb-oxy-lic acid dimethyl sulfoxide monosolvate], C 6 H 6 O 7 ·C 2 H 6 OS, (I), and hibiscus acid dimethyl ester [systematic name: dimethyl (2 S ,3 R )-3-hy-droxy-5-oxo-2,3,4,5-tetra-hydro-furan-2,3-di-carboxyl-ate], C 8 H 10 O 7 , (II). Compound (I) forms a layered structure with alternating layers of lactone and solvent mol-ecules, that include a two-dimensional hydrogen-bonding construct. Compound (II) has two crystallographically independent and conformationally similar mol-ecules per asymmetric unit and forms a one-dimensional hydrogen-bonding construct. The known absolute configuration for both compounds has been confirmed.

Superior Energetic Materials that Contain Carbocations and Anions. Energetic Materials Restricted in Composition to C, H, N, and O Atoms

DTIC Science & Technology

1993-10-30

AMXRO-IP-Library. Summary Thiourea condensed with 1,4-diformnyl-2,3,5,6-tetrahydroxypiperazine 14 in the presence of 3 hydrochloric acid to give 2,6...b:4’,5"-e]pyrazine 20 to 2- oxo-2,3-dihydro-1,3-dinitro-lH-imidazo[4,5-b]pyrazine 21 was brought about by hydrochloric acid . Treatment with lithium...reaction with tert-butyl amine, and converted to 4,8-dihydro-4,8-dinitro- 1H,5H-diimidazo[4,5-b:4’,5’-e]pyrazine-2,6-disulfonic acid 17 by nitric acid

Crystal structures of 4-meth-oxy-benzoic acid-1,3-bis-(pyridin-4-yl)propane (2/1) and biphenyl-4,4'-di-carb-oxy-lic acid-4-meth-oxy-pyridine (1/2).

PubMed

Gotoh, Kazuma; Ishida, Hiroyuki

2017-07-01

The crystal structures of two hydrogen-bonded compounds, namely 4-meth-oxy-benzoic acid-1,3-bis-(pyridin-4-yl)propane (2/1), C 13 H 14.59 N 2 ·C 8 H 7.67 O 3 ·C 8 H 7.74 O 3 , (I), and biphenyl-4,4'-di-carb-oxy-lic acid-4-meth-oxy-pyridine (1/2), C 14 H 9.43 O 4 ·C 6 H 7.32 NO·C 6 H 7.25 NO, (II), have been determined at 93 K. In (I), the asymmetric unit consists of two crystallographically independent 4-meth-oxy-benzoic acid mol-ecules and one 1,3-bis-(pyridin-4-yl)propane mol-ecule. The asymmetric unit of (II) comprises one biphenyl-4,4'-di-carb-oxy-lic acid mol-ecule and two independent 4-meth-oxy-pyridine mol-ecules. In each crystal, the acid and base mol-ecules are linked by short O-H⋯N/N-H⋯O hydrogen bonds, in which H atoms are disordered over the acid O-atom and base N-atom sites, forming a linear hydrogen-bonded 2:1 or 1:2 unit of the acid and the base. The 2:1 units of (I) are linked via C-H⋯π, π-π and C-H⋯O inter-actions into a tape structure along [101], while the 1:2 units of (II) form a double-chain structure along [-101] through π-π and C-H⋯O inter-actions.

A series of coordination polymers constructed from R-isophthalic acid (R=–SO{sub 3}H, –NO{sub 2}, and –OH) and N-donor ligands: Syntheses, structures and fluorescence properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Yong-Hong, E-mail: zhou21921@sina.com; Zhou, Xu-Wan; Zhou, Su-Rong

Six novel Zn(II), Cd(II), and Cu(II) mixed-ligand coordination complexes, namely, [Zn{sub 2}Na(sip){sub 2}(bpp){sub 3}(Hbpp)(H{sub 2}O){sub 2}]·8H{sub 2}O (1), [Cd{sub 3}(sip){sub 2}(nbi){sub 6}(H{sub 2}O){sub 2}]·7H{sub 2}O (2), [Zn(sip)(nbi){sub 2}(H{sub 2}O)]·Hnbi·3H{sub 2}O (3), [Cd(hip)(nbi){sub 2}(H{sub 2}O)]·nbi·5H{sub 2}O (4), [Cd{sub 2}(nip){sub 2}(nbi){sub 2}(H{sub 2}O){sub 2}]·DMF (5), and [Cu(nip)(nbi)(H{sub 2}O){sub 2}]·H{sub 2}O (6) (H{sub 3}sip=5-sulfoisophthalic acid, H{sub 2}hip=5-hydroxylisophthalic acid, H{sub 2}nip=5-nitroisophthalic acid, bpp=1,3-bis(4-pyridyl)propane, and nbi=6-nitrobenzimidazole) have been synthesized hydrothermally by the self-assembly of R-isophthalic acid (R=–SO{sub 3}H, –NO{sub 2}, and –OH) and N-donor ligands. Single crystal X-ray analyses reveal that two Zn(II) ions and one Na(I) ion of complex 1 are linked through Omore » atoms to generate a 1D linear chain. Then the 2D supramolecular architectures are constructed via intermolecular interactions. In complex 2, the Cd1 ions are connected by bridging carboxyl groups from sip{sup 3−} anions to form 1D double chain, which are further connected by Cd2 ions to afford 2D layer structure. The adjacent 2D layers are further linked via hydrogen-bonding interactions to give 3D supramolecular network. Compounds 3–5 show 1D chain structures, which are assembled into 2D or 3D supramolecular frameworks via weak interactions. In compound 6, the Cu(II) ions are bridged by the nip{sup 2−} ligands to form 48-membered ring, which is assembled into 1Dchain via the π-π stacking interaction. In addition, the thermal stabilities and fluorescence properties of these compounds have also been studied. - Graphical abstract: A series of Cd(II)/Zn(II)/ Cu(II) coordination polymers based on R-isophthalic acid (R=–SO{sub 3}H, –NO{sub 2}, and –OH) and N-donor ligands have been synthesized under hydrothermal conditions and structurally characterized. Photoluminescent properties have been discussed. - Highlights: • Six coordination polymers were synthesized based on mixed-ligand strategy. • The polycarboxylate acids play a crucial role in determining the final structures. • Each complex shows diverse structures and different supramolecular interactions.« less

[Mechanism and performance of styrene oxidation by O3/H2O2].

PubMed

He, Jue-Cong; Huang, Qian-Ru; Ye, Qi-Hong; Luo, Yu-Wei; Zhang, Zai-Li; Fan, Qing-Juan; Wei, Zai-Shan

2013-10-01

It can produce a large number of free radicals in O3/H2O2, system, ozone and free radical coupling oxidation can improve the styrene removal efficiency. Styrene oxidation by O3/H2O2 was investigated. Ozone dosage, residence time, H2o2 volume fraction, spray density and molar ratio of O3/C8H8 on styrene removal were evaluated. The experimental results showed that styrene removal efficiency achieved 85.7%. The optimal residence time, H2O2, volume fraction, spray density and O3/C8H8 molar ratio were 20. 6 s, 10% , 1.72 m3.(m2.h)-1 and 0.46, respectively. The gas-phase degradation intermediate products were benzaldehyde(C6H5CHO) and benzoic acid (C6H5 COOH) , which were identified by means of gas chromatography-mass spectrometry(GC-MS). The degradation mechanism of styrene is presented.

Structural variations in terbium(III) complexes with 1,3-adamantanedicarboxylate and diverse co-ligands

NASA Astrophysics Data System (ADS)

Thuéry, Pierre

2015-07-01

Terbium nitrate was reacted with 1,3-adamantanedicarboxylic acid (LH2) under solvo-hydrothermal conditions with either N,N-dimethylformamide (DMF) or N,N-dimethylacetamide (DMA) as organic solvents. Hydrolysation of the latter co-solvents resulted in the formation of formate or acetate ions, which are present as co-ligands in the 1D coordination polymer [Tb(L)(HCOO)(H2O)2] (1) and the 2D assembly [Tb(L)(CH3COO)(H2O)] (2). The increase in dimensionality in the latter arises from the higher connectivity provided by acetate versus formate, the L2- ligand being bis-chelating in both cases. The complex [Tb2(L)3(H2O)5][Tb2(L)3(H2O)4]·3H2O (3), another 1D species, crystallizes alongside crystals of 2. Further addition of cucurbit[6]uril (CB6), with DMF as co-solvent, gave the two complexes [Tb2(L)2(CB6)(H2O)6](NO3)2·6H2O (4) and [H2NMe2]2[Tb(L)(HCOO)2]2·CB6·3H2O (5). Complex 4 crystallizes as a 3D framework in which Tb(L)+ chains are connected by tetradentate CB6 molecules, while 5 unites a carboxylate-bridged anionic 2D planar assembly and layers of CB6 molecules with counter-cations held at both portals.

Lanthanide contraction effect on crystal structures of lanthanide coordination polymers with cyclohexanocucurbit[6]uril ligand

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zheng, Li-Mei; Liu, Jing-Xin, E-mail: jxliu411@ahut.edu.cn

A series of compounds based on the macrocyclic ligand cyclohexanocucurbit[6]uril (Cy6Q[6]) with formulas (Ln(H{sub 2}O){sub 6}Cy6Q[6])·2(CdCl{sub 4})·H{sub 3}O·xH{sub 2}O [isomorphous with Ln=La (1), Ce (2), Pr (3) and Nd (4), x=11 (1), 11 (2), 10 (3) and 11 (4)], (Sm(H{sub 2}O){sub 5}Cy6Q[6])·2(CdCl{sub 4})·H{sub 3}O·10H{sub 2}O (5) and (Ln(H{sub 2}O){sub 5}(NO{sub 3})@Cy6Q[6])·2(CdCl{sub 4})·2H{sub 3}O·xH{sub 2}O [isomorphous with Ln=Gd (6), Tb (7) and Dy (8), x=8 (6), 6 (7) and 6 (8)], have been successfully synthesized by the self-assembly of Cy6Q[6] with the corresponding lanthanide nitrate under hydrochloric acid aqueous solution in the presence of CdCl{sub 2}. Single-crystal X-ray diffraction analyses revealedmore » that compounds 1–8 all crystallize in monoclinic space group P2{sub 1}/c, and display 1D coordination polymer structures. The lanthanide contraction effect on the structures of 1–8 has also been investigated and discussed in detail. In contrast, the reaction of Cy6Q[6] with the Ho(NO){sub 3}, Tm(NO){sub 3}, Yb(NO){sub 3} under the same conditions resulted in the compounds 9–11 with formulas Cy6Q[6]·2(CdCl{sub 4})·2H{sub 3}O·xH{sub 2}O [isomorphous with x=10 (9), 10 (10), and 9 (11)], in which no lanthanide cations are observed. The structural difference of these compounds indicates that the Cy6Q[6] may be used in the separation of lanthanide cations. - Graphical abstract: The reaction of cyclohexanocucurbit[6]uril with lanthanide ions (La{sup 3+}, Ce{sup 3+}, Pr{sup 3+}, Nd{sup 3+}, Sm{sup 3+}, Gd{sup 3+}, Tb{sup 3+}, Dy{sup 3+}, Ho{sup 3+}, Tm{sup 3+} and Yb{sup 3+}) under hydrochloric acid in the presence of CdCl{sub 2} resulted in eleven compounds, which demonstrate interesting lanthanide contraction effect and provide a means of separating lanthanide ions. - Highlights: • Eleven compounds of the Ln{sup 3+} with the Cy6Q[6] were synthesized and described. • Compounds 1-8 demonstrate interesting lanthanide contraction effect. • In solid-state structures of compounds 9-11, no lanthanide ions were observed. • This study provides a means of separating lanthanides cations.« less

Tris[(6S)-6-hy-droxy-4-epi-shikimic acid] monohydrate: an enanti-omerically pure hy-droxy-lated shikimic acid derived from methyl shikimate.

PubMed

Griesbeck, Axel G; Miara, Claus; Neudörfl, Jörg-M

2012-11-01

The title compound, 3C(7)H(10)O(6)·H(2)O, is the enanti-omerically pure product of a multi-step synthesis from the enanti-omerically pure natural shikimic acid. The asymmetric unit contains three mol-ecules of the acid and one mol-ecule of water. The cyclo-hexene rings of the acids have half-chair conformations. The carboxyl-ate, the four hydroxide groups and the additional water mol-ecule form a complex three-dimensional hydrogen-bonding network.

Structural diversity and photocatalytic properties of Cd(II) coordination polymers constructed by a flexible V-shaped bipyridyl benzene ligand and dicarboxylate derivatives.

PubMed

Liu, Lei-Lei; Yu, Cai-Xia; Ma, Feng-Ji; Li, Ya-Ru; Han, Jing-Jing; Lin, Lu; Ma, Lu-Fang

2015-01-28

Hydrothermal reactions of Cd(OAc)2·2H2O with a flexible V-shaped bipyridyl benzene ligand and five benzenedicarboxylic acid derivatives gave rise to five new coordination polymers i.e., [Cd(1,4-BDC)(bpmb)(H2O)]n (1), {[Cd(1,3-BDC)(bpmb)]·0.125H2O}n (2), [Cd2(5-Me-1,3-BDC)2(bpmb)2]n (3), [Cd(5-NO2-1,3-BDC)(bpmb)(H2O)]n (4) and [Cd(5-OH-1,3-BDC)(bpmb)(H2O)]n (5) (bpmb = 1,3-bis(pyridine-3-ylmethoxy)benzene, 1,4-H2BDC = 1,4-benzenedicarboxylic acid, 1,3-H2BDC = 1,3-benzenedicarboxylic acid, 5-Me-1,3-H2BDC = 5-methyl-1,3-benzenedicarboxylic acid, 5-NO2-1,3-H2BDC = 5-nitro-1,3-benzenedicarboxylic acid, 5-OH-1,3-H2BDC = 5-hydroxy-1,3-benzenedicarboxylic acid). Their structures have been determined by single-crystal X-ray diffraction analyses, elemental analyses, IR spectra, powder X-ray diffraction (PXRD) and thermogravimetric analyses (TGA). Compound 1 is a two-fold interpenetrating network showing the coexistence of polyrotaxane and polycatenane characters. Compounds 2 and 3 exhibit similar 2D (3,5)-connected (4(2)·6(7)·8)(4(2)·6) nets in which the bpmb ligands work as lockers in interlocking 1D [Cd(1,3-BDC/5-Me-1,3-BDC)]n chains. Compound 4 shows a 2D 4-connected (6(6)) sandwich-like structure with differently oriented [Cd(5-NO2-1,3-BDC)]n chains. Compound 5 is a 3D supramolecular pcu net based on a 1D ladder-shaped chain. These results suggest that the substituted positions of carboxylate groups and changes in substituted R groups in the 5-position of BDC ligands have significant effect on the final structures. These compounds exhibited relatively good photocatalytic activity towards the degradation of methylene blue (MB) in aqueous solution under UV irradiation. Moreover, solid-state photoluminescence properties of 1-5 were also investigated.

[Determination of peracetic acid and hydrogen peroxide in a preparation].

PubMed

Bodiroga, Milanka; Ognjanović, Jasminka

2002-01-01

Iodometric and permanganometric titrations were used for determination of peracetic acid and hydrogen peroxide (H2O2) in the mixture. Two procedures were described and compared. Titrations could be done in only one vessel, in the same reaction mixture, when iodometric titration of peracetic acid was continued after the permanganometric titration of H2O2, (procedure A). Peracetic acid and H2O2, as oxidizing agents, reacted with potassium iodide in an acid medium, evolving iodine. This reaction was used for the quantitative iodometric determination of total peroxide in procedure B. H2O2 reacted with potassium permanganate in acid medium, but peracetic acid did not react under the same conditions. That made possible the selective permanganometric determination of H2O2 in the presence of peracetic acid. The procedure B was performed in two titration vessels (KV = 3.4% for peracetic acid, 0.6% for H2O2). The procedure A for iodometric determination of peracetic acid in one titration vessel after permanganometric titration of H2O2 was recommended (KV = 2.5% for peracetic acid, 0.45% for H2O2).

Supra-molecular architecture in a co-crystal of the N(7)-H tautomeric form of N (6)-benzoyl-adenine with adipic acid (1/0.5).

PubMed

Swinton Darious, Robert; Thomas Muthiah, Packianathan; Perdih, Franc

2016-06-01

The asymmetric unit of the title co-crystal, C12H9N5O·0.5C6H10O4, consists of one mol-ecule of N (6)-benzoyl-adenine (BA) and one half-mol-ecule of adipic acid (AA), the other half being generated by inversion symmetry. The dihedral angle between the adenine and phenyl ring planes is 26.71 (7)°. The N (6)-benzoyl-adenine mol-ecule crystallizes in the N(7)-H tautomeric form with three non-protonated N atoms. This tautomeric form is stabilized by intra-molecular N-H⋯O hydrogen bonding between the carbonyl (C=O) group and the N(7)-H hydrogen atom on the Hoogsteen face of the purine ring, forming an S(7) ring motif. The two carboxyl groups of adipic acid inter-act with the Watson-Crick face of the BA mol-ecules through O-H⋯N and N-H⋯O hydrogen bonds, generating an R 2 (2)(8) ring motif. The latter units are linked by N-H⋯N hydrogen bonds, forming layers parallel to (10-5). A weak C-H⋯O hydrogen bond is also present, linking adipic acid mol-ecules in neighbouring layers, enclosing R (2) 2(10) ring motifs and forming a three-dimensional structure. C=O⋯π and C-H⋯π inter-actions are also present in the structure.

Formation of oxidizing species via irradiation of perchlorates using high-energy electrons and D 2 + ions

NASA Astrophysics Data System (ADS)

Crandall, Parker B.; Gillis-Davis, Jeffrey J.; Kaiser, Ralf-Ingo

2016-10-01

The perchlorate ion (ClO4-) has garnered particular interest in recent years following the discovery of perchlorate salts in the Martian regolith at levels of 0.4-0.6 wt% by the Phoenix lander in 2006 and Mars Science Laboratory's Curiosity rover in 2013. Due to their oxidizing properties, perchlorates are suspected to play a contributing role to the surprising lack of organics on the Martian surface. In this study, magnesium perchlorate hexahydrate (Mg(ClO4)2●6H2O) samples were irradiated with monoenergetic beams of 5 keV electrons and D2+ ions separately, sequentially, and simultaneously to simulate the effects of galactic cosmic ray exposure of perchlorates. The irradiation experiments were carried out under ultra-high vacuum conditions at 50 K, after which the samples were slowly heated to 300 K (0.5 K min-1) while desorbing products were monitored by quadrupole mass spectrometry. In all cases, molecular oxygen (O2) was detected upon the onset of irradiation and again during the warmup phase. In the case of simultaneous irradiation, deuterated water (D2O) and deuterium peroxide (D2O2) were also detected as the sample was heated whereas in the D2+ experiment small amounts of D2O2 was found exclusively. When samples were irradiated sequentially, the production of D2O2 was dependent upon the sample being irradiated with D2+ ions prior to electrons. These experiments show that perchlorates are capable of producing multiple oxidizing agents (O2, D2O2) which may also account for the lack of organics on the Martian surface.

Decolorizing of azo dye Reactive red 24 aqueous solution using exfoliated graphite and H2O2 under ultrasound irradiation.

PubMed

Li, Mei; Li, Ji-Tai; Sun, Han-Wen

2008-07-01

At its natural pH (6.95), the decolorization of Reactive red 24 in ultrasound, ultrasound/H2O2, exfoliated graphite, ultrasound/exfoliated graphite, exfoliated graphite/H2O2 and ultrasound/exfoliated graphite/H2O2 systems were compared. An enhancement was observed for the decolorization in ultrasound/exfoliated graphite/H2O2 system. The effect of solution pH, H2O2 and exfoliated graphite dosages, and temperature on the decolorization of Reactive red 24 was investigated. The sonochemical treatment in combination with exfoliated graphite/H2O2 showed a synergistic effect for the decolorization of Reactive red 24. The results indicated that under proper conditions, there was a possibility to remove Reactive red 24 very efficient from aqueous solution. The decolorization of other azo dyes (Reactive red 2, Methyl orange, Acid red 1, Acid red 73, Acid red 249, Acid orange 7, Acid blue 113, Acid brown 75, Acid green 20, Acid yellow 42, Acid mordant brown 33, Acid mordant yellow 10 and Direct green 1) was also investigated, at their natural pH.

Improving the Explosive Performance of Aluminum Nanoparticles with Aluminum Iodate Hexahydrate (AIH).

PubMed

Gottfried, Jennifer L; Smith, Dylan K; Wu, Chi-Chin; Pantoya, Michelle L

2018-05-23

A new synthesis approach for aluminum particles enables an aluminum core to be passivated by an oxidizing salt: aluminum iodate hexahydrate (AIH). Transmission electron microscopy (TEM) images show that AIH replaces the Al 2 O 3 passivation layer on Al particles that limits Al oxidation. The new core-shell particle reactivity was characterized using laser-induced air shock from energetic materials (LASEM) and results for two different Al-AIH core-shell samples that vary in the AIH concentration demonstrate their potential use for explosive enhancement on both fast (detonation velocity) and slow (blast effects) timescales. Estimates of the detonation velocity for TNT-AIH composites suggest an enhancement of up to 30% may be achievable over pure TNT detonation velocities. Replacement of Al 2 O 3 with AIH allows Al to react on similar timescales as detonation waves. The AIH mixtures tested here have relatively low concentrations of AIH (15 wt. % and 6 wt. %) compared to previously reported samples (57.8 wt. %) and still increase TNT performance by up to 30%. Further optimization of AIH synthesis could result in additional increases in explosive performance.

Room temperature synthesis and enhanced photocatalytic property of CeO2/ZnO heterostructures

NASA Astrophysics Data System (ADS)

Wang, Chao; Fan, Huiqing; Ren, Xiaohu; Fang, Jiawen

2018-02-01

To achieve better photocatalytic performance, we proposed a facile solid-state reaction method to produce CeO2/ZnO heterostructures. Ceria and zinc oxide were synthesized simultaneously by thoroughly grinding the mixture of zinc acetate dihydrate, cerium nitrate hexahydrate and sodium hydroxide. The morphology of the as-prepared heterostructures varies dramatically as different amount of ceria was introduced in the composition. The photocatalytic performance of CeO2/ZnO heterojunctions was 4.6 times higher than that of pure ZnO. The enhanced photocatalytic activity could be ascribed to that more electrons and holes could transport to the surface of catalysts and react with the pollution due to the extended light-responsive range, accelerated migration, increased specific surface area and suppressed recombination of photogenerated carriers.

Structural modulation and luminescent properties of four CdII coordination architectures based on 3-(pyridin-4-yl)-5-(pyrazin-2-yl)-1H-1,2,4-triazole and flexible/rigid dicarboxylate ligands

NASA Astrophysics Data System (ADS)

Xia, Liang; Dong, Wen-Wen; Ye, Xiao; Zhao, Jun; Li, Dong-Sheng

2016-10-01

To systematically investigate the influence of the flexible or rigid auxiliary ligands on the structures and properties of transition metal compounds, we synthesized four new d10 coordination polymers (CPs) from 3-(pyridin-4-yl)-5-(pyrazin-2-yl)-1H-1,2,4-triazole (4-Hpzpt) and flexible/rigid dicarboxylate ligands, [Cd(4-pzpt)2]n (1), [Cd3(4-pzpt)2(suc)2]n (2), [Cd2(4-Hpzpt)(nbc)2(H2O)]n (3) and {[Cd2(4-pzpt)2(tfbdc)(H2O)4]·H2O}n (4) (H2suc=1,2-ethanedicarboxylic acid, H2nbc=hthalene-1,4-dicarboxylic acid, H2tfbdc =2,3,5,6-tetrafluoroterephthalic acid). Single crystal X-ray analysis indicates that compound 1 shows a 44-sql layer, which is extended to a 3D network via nonclassical C-H…N hydrogen bonds. Compound 2 possesses a 6-connected pcu-4120.63 net composed of trinuclear CdII-clusters. Compound 3 represents a rare 3D (3,4,4,5)-connected topology with a Schläfli symbol of (4·6·7)(4·53·72)(53·6·7·9)(42·55·6·72). Compound 4 exhibits a 2D+2D→2D parallel interpenetrated 63-hcb network. The adjacent 2D networks are interdigitated with each other to form the resulting 3D supramolecular architecture through classical O-H…N and O-H…O hydrogen bonds. Structural diversities indicate that the nature of flexible/rigid-dicarboxlates plays crucial roles in modulating structures of these compounds. Moreover, the luminescent properties of them have been briefly investigated.

Synthesis and high proton conductive performance of a quaternary vanadomolybdotungstosilicic heteropoly acid.

PubMed

Cai, Huaxue; Wu, Xuefei; Wu, Qingyin; Yan, Wenfu

2016-09-28

A new vanadium and molybdenum-substituted quaternary silicon-containing heteropoly acid H6SiW9MoV2O40·15H2O has been synthesized in this paper by the stepwise acidification and the stepwise addition of elemental solutions. The structural feature and hydration of this product were characterized by IR, UV, XRD and TG-DTA, and its proton conductivity was measured by electrochemical impedance spectroscopy (EIS). The result of EIS shows that H6SiW9MoV2O40·15H2O is a solid high-proton conductor with a conductivity of 6.01 × 10(-3) S cm(-1) at 22 °C and 80% relative humidity, which increases at higher temperatures. Its conductive activation energy is 27.5 kJ mol(-1), which suggests that the mechanism of proton conduction is dominated by the vehicle mechanism.

Two novel metal–organic coordination polymers based on diphosphonate and oxalate: Synthesis, structures and properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Niu, Qing-Jun; Zheng, Yue-Qing, E-mail: yqzhengmc@163.com; Zhou, Lin-Xia

2015-07-15

Two 2-(1-imidazole)-1-hydroxyl-1,1'-ethylidenediphosphonato and oxalic acid bridged coordination polymers (H{sub 2}en)[Co{sub 3}(H{sub 2}zdn){sub 2}(ox)(H{sub 2}O){sub 2}] (1) and Cd{sub 2}(H{sub 2}zdn)(ox){sub 0.5}(H{sub 2}O) (2) (2-(1-imidazole)-1-hydroxyl-1,1'-ethylidenediphosphonic acid=H{sub 5}zdn; oxalic acid=H{sub 2}ox) were synthesized under hydrothermal conditions and characterized by the infrared (IR), thermogravimetric analyses (TGA), elemental analyses (EA) and X-ray diffraction (XRD). Compound 1 is bridged by phosphonate anions to 1D chain, and further linked by oxalate anions to 2D layer. Compound 2 is bridged by O–P–O units of H{sub 5}zdn to the layer, and then pillared by oxalate anions to generate 3D frameworks. Compound 1 shows anti-ferromagnetic behaviors analyzed with themore » temperature-dependent zero-field ac magnetic susceptibilities, while compound 2 exhibits an influence on the luminescent property. - Graphical abstract: Linked by oxalate, two zoledronate-based metal–organic frameworks are synthesized, which exhibits the different frameworks. Magnetism and luminescent properties have been studied. The weak antiferromagnetic coupling is conducted in 1. - Highlights: • Compound 1 and 2 are first linked by oxalate anion based on zoledronic acid. • Compound 1 generates a classic “dia Diamond” (6{sup 6}) topology. • Compound 2 exhibits a (4{sup 4}·6{sup 2})(4{sup 4}·6{sup 6}) topology. • Magnetism and luminescent properties of 1 and 2 have been studied, respectively.« less

Transcriptome Analysis of H2O2-Treated Wheat Seedlings Reveals a H2O2-Responsive Fatty Acid Desaturase Gene Participating in Powdery Mildew Resistance

PubMed Central

Tang, Lichuan; Zhao, Guangyao; Zhu, Mingzhu; Chu, Jinfang; Sun, Xiaohong; Wei, Bo; Zhang, Xiangqi; Jia, Jizeng; Mao, Long

2011-01-01

Hydrogen peroxide (H2O2) plays important roles in plant biotic and abiotic stress responses. However, the effect of H2O2 stress on the bread wheat transcriptome is still lacking. To investigate the cellular and metabolic responses triggered by H2O2, we performed an mRNA tag analysis of wheat seedlings under 10 mM H2O2 treatment for 6 hour in one powdery mildew (PM) resistant (PmA) and two susceptible (Cha and Han) lines. In total, 6,156, 6,875 and 3,276 transcripts were found to be differentially expressed in PmA, Han and Cha respectively. Among them, 260 genes exhibited consistent expression patterns in all three wheat lines and may represent a subset of basal H2O2 responsive genes that were associated with cell defense, signal transduction, photosynthesis, carbohydrate metabolism, lipid metabolism, redox homeostasis, and transport. Among genes specific to PmA, ‘transport’ activity was significantly enriched in Gene Ontology analysis. MapMan classification showed that, while both up- and down- regulations were observed for auxin, abscisic acid, and brassinolides signaling genes, the jasmonic acid and ethylene signaling pathway genes were all up-regulated, suggesting H2O2-enhanced JA/Et functions in PmA. To further study whether any of these genes were involved in wheat PM response, 19 H2O2-responsive putative defense related genes were assayed in wheat seedlings infected with Blumeria graminis f. sp. tritici (Bgt). Eight of these genes were found to be co-regulated by H2O2 and Bgt, among which a fatty acid desaturase gene TaFAD was then confirmed by virus induced gene silencing (VIGS) to be required for the PM resistance. Together, our data presents the first global picture of the wheat transcriptome under H2O2 stress and uncovers potential links between H2O2 and Bgt responses, hence providing important candidate genes for the PM resistance in wheat. PMID:22174904

Calculation of the Standard Molal Thermodynamic Properties of Crystalline, Liquid, and Gas Organic Molecules at High Temperatures and Pressures

NASA Astrophysics Data System (ADS)

Helgeson, Harold C.; Owens, Christine E.; Knox, Annette M.; Richard, Laurent

1998-03-01

Calculation of the thermodynamic properties of organic solids, liquids, and gases at high temperatures and pressures is a requisite for characterizing hydrothermal metastable equilibrium states involving these species and quantifying the chemical affinities of irreversible reactions of organic molecules in natural gas, crude oil, kerogen, and coal with minerals and organic, inorganic, and biomolecular aqueous species in interstitial waters in sedimentary basins. To facilitate calculations of this kind, coefficients for the Parameters From Group Contributions (PFGC) equation of state have been compiled for a variety of groups in organic liquids and gases. In addition, molecular weights, critical temperatures and pressures, densities at 25°C and 1 bar, transition, melting, and boiling temperatures ( Tt,Pr, Tm,Pr, and Tv,Pr, respectively) and standard molal enthalpies of transition (Δ H° t,Pr), melting (Δ H° m,Pr), and vaporization (Δ H° v,Pr) of organic species at 1 bar ( Pr) have been tabulated, together with an internally consistent and comprehensive set of standard molal Gibbs free energies and enthalpies of formation from the elements in their stable state at 298.15 K ( Tr) and Pr (Δ G° f and Δ H° f, respectively). The critical compilation also includes standard molal entropies ( S°) and volumes ( V°) at Tr and Pr, and standard molal heat capacity power function coefficients to compute the standard molal thermodynamic properties of organic solids, liquids, and gases as a function of temperature at 1 bar. These properties and coefficients have been tabulated for more than 500 crystalline solids, liquids, and gases, and those for many more can be computed from the equations of state group additivity algorithms. The crystalline species correspond to normal alkanes (C nH 2( n+1) ) with carbon numbers ( n, which is equal to the number of moles of carbon atoms in one mole of the species) ranging from 5 to 100, and 23 amino acids including glycine (C 2H 5NO 2), alanine (C 3H 7NO 2), valine (C 5H 11NO 2), leucine (C 6H 13NO 2), isoleucine (C 6H 13NO 2), aspartic acid (C 4H 7NO 4), glutamic acid (C 5H 9NO 4), asparagine (C 4H 8N 2O 3), glutamine (C 5H 10N 2O 3), proline (C 5H 9NO 2), phenylalanine (C 9H 11NO 2), tryptophan (C 11H 12N 2O 2), methionine (C 5H 11SNO 2), serine (C 3H 7NO 3), threonine (C 4H 9NO 3), cysteine (C 3H 7SNO 2), tyrosine (C 9H 11NO 3), lysine (C 6H 14N 2O 2), lysine:HCl (C 6H 15N 2O 2Cl), arginine (C 6H 14N 4O 2), arginine:HCl (C 6H 15N 4O 2Cl), histidine (C 6H 9N 3O 2), and histidine:HCl (C 6H 10N 3O 2Cl). The data for the latter compounds permit calculation of the standard molal thermodynamic properties of protein unfolding in biogeochemical processes (Helgeson et al 1998). The liquids and gases considered in the present study include normal alkanes (C nH 2( n+1) ) for carbon numbers ranging from 1 to 100, 2- and 3-methylalkanes (C nH 2( n+1) ) for 4 ≤ n ≤ 20 and 6 ≤ n ≤ 20, respectively, 2,3-dimethylpentane (C 7H 16), 4-methylheptane (C 8H 18), cycloalkanes (C nH 2 n) for 3 ≤ n ≤ 8, methylated benzenes (C nH 2( n-3) ) for 7 ≤ n ≤ 12, normal alkylbenzenes (C nH 2( n-3) ) for 6 ≤ n ≤ 20, normal 1-alcohols (C nH 2( n+1) O) for 1 ≤ n ≤ 20, ethylene glycol (C 2H 6O 2), glycerol (C 3H 8O 3), normal 1-alkanethiols (C nH 2( n+1) S) for 1 ≤ n ≤ 20, normal carboxylic acids (C nH 2 nO 2) for 2 ≤ n ≤ 20, and the following miscellaneous species: 2-thiabutane (C 3H 8S), thiophene (C 4H 4S), thiophenol (C 6H 6S), acetone (C 3H 6O), 2-butanone (C 4H 8O), ethyl acetate (C 4H 8O 2), pyridine (C 5H 5N), 3-methylpyridine (C 6H 7N), and quinoline (C 9H 7N). One additional liquid (2-methylthiacyclopentane (C 5H 10S)) was also considered along with crystalline and gaseous carbazole (C 12H 9N). The thermodynamic data and equations summarized below can be used together with the standard molal thermodynamic properties of high molecular weight organic compounds ( Richard and Helgeson 1995, Richard and Helgeson 1998a, Richard and Helgeson 1998b) and minerals, inorganic gases, and aqueous species, including biomolecules ( Johnson et al 1992; Shock 1992a, Shock 1994, Shock 1995; Shock et al 1997; Shock and Koretsky 1993, Shock and Koretsky 1995; Sassani and Shock 1992, Sassani and Shock 1994; Schulte and Shock 1993, Schulte and Shock 1995; Oelkers et al 1995; Amend and Helgeson 1997a, Amend and Helgeson 1997b, Amend and Helgeson 1997c, Amend and Helgeson 1998; Sverjensky et al 1997) to compute equilibrium constants and chemical affinities for a wide variety of organic-inorganic reactions in geochemical and biochemical processes at both high and low temperatures and pressures. Unless indicated otherwise, all amino acid designations in the present communication refer to the L-α form.

Extracellular acidosis and very low [Na+ ] inhibit NBCn1- and NHE1-mediated net acid extrusion from mouse vascular smooth muscle cells.

PubMed

Bonde, L; Boedtkjer, E

2017-10-01

The electroneutral Na + , HCO3- cotransporter NBCn1 and Na + /H + exchanger NHE1 regulate acid-base balance in vascular smooth muscle cells (VSMCs) and modify artery function and structure. Pathological conditions - notably ischaemia - can dramatically perturb intracellular (i) and extracellular (o) pH and [Na + ]. We examined effects of low [Na + ] o and pH o on NBCn1 and NHE1 activity in VSMCs of small arteries. We measured pH i by 2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein-based fluorescence microscopy of mouse mesenteric arteries and induced intracellular acidification by NH4+ prepulse technique. NBCn1 activity - defined as Na + -dependent, amiloride-insensitive net base uptake with CO 2 /HCO3- present - was inhibited equally when pH o decreased from 7.4 (22 mm HCO3-/5% CO 2 ) by metabolic (pH o 7.1/11 mm HCO3-: 22 ± 8%; pH o 6.8/5.5 mm HCO3-: 61 ± 7%) or respiratory (pH o 7.1/10% CO 2 : 35 ± 11%; pH o 6.8/20% CO 2 : 56 ± 7%) acidosis. Extracellular acidosis more prominently inhibited NHE1 activity - defined as Na + -dependent net acid extrusion without CO 2 /HCO3- present - at both pH o 7.1 (45 ± 9%) and 6.8 (85 ± 5%). Independently of pH o , lowering [Na + ] o from 140 to 70 mm reduced NBCn1 and NHE1 activity <20% whereas transport activities declined markedly (25-50%) when [Na + ] o was reduced to 35 mm. Steady-state pH i decreased more during respiratory (ΔpH i /ΔpH o  = 71 ± 4%) than metabolic (ΔpH i /ΔpH o  = 30 ± 7%) acidosis. Extracellular acidification inhibits NBCn1 and NHE1 activity in VSMCs. NBCn1 is equivalently inhibited when pCO 2 is raised or [HCO3-] o decreased. Lowering [Na + ] o inhibits NBCn1 and NHE1 markedly only below the typical physiological and pathophysiological range. We propose that inhibition of Na + -dependent net acid extrusion at low pH o protects against cellular Na + overload at the cost of intracellular acidification. © 2017 Scandinavian Physiological Society. Published by John Wiley & Sons Ltd.

Assembly of a basket-like {Sr ⊂ P6Mo18O73} cage from 0D dimmer to 2D network and its photo-/electro-catalytic properties.

PubMed

Zhang, He; Lv, Jing-Hua; Yu, Kai; Wang, Chun-mei; Wang, Chun-xiao; Sun, Di; Zhou, Bai-bin

2015-07-28

A series of basket-like heteropoly blues, formulated as (H4bth)[{Cu(H2O)}2{Sr ⊂ P6MoV2MoVI16O73}]·4H2O (1), {H2bih}3[{FeII(H2O)2}{Sr ⊂ P6MoV2MoVI16O73}]·2H2O (2), (H2bih)3[{CoII(H2O)2}{Sr ⊂ P6MoV2MoVI16O73}]·2H2O (3), (H2bih)3[{NiII(H2O)2}{Sr ⊂ P6MoV2MoVI16O73}]·2H2O (4), (H2bih)2(H2bip)[{Zn (H2O)0.5}{Sr ⊂ P6MoV2MoVI16O73}]·5.5H2O (5), (bth = 1,6-bis(triazole)hexane; bih = 1,6-bis(imidazol)hexane; bip = 1,5-bis(imidazol)pentane) have been synthesized hydrothermally and fully characterized. The structural analysis shows that all the compounds contain two electron reduced polyanions [Sr ⊂ P6MoV2MoVI16O73]8− (abbreviated as {P6Mo18O73}), which consists of a tetra vacant γ-Dawson-type{P2Mo14} unit and a “handle”-shaped {P4Mo4} segment encapsulating a Sr2+ cation in the central cavity. Compound 1 is a 6-connected two-dimensional (2D) layer, which represents the first 2D assembly of basket-type polyoxometalates. Compounds 2–4 are isostructural one-dimensional zigzag chains linked by an M(H2O)2 linker (M = iron for 2, cobalt for 3, and nickel for 4). Compound 5 is a dimeric cluster supported by a binuclear {Zn2(H2O)} unit. The optical band gaps of 1–5 reveal their semiconductive natures. The compounds if used as photocatalysts exhibit a universal high efficiency degradation ability for dyes such as methylene blue, Rhodamine B, and Azon phloxine. The lifetime and reaction mechanism of the catalysts were investigated with a series of experiments. The compounds also show good bifunctional electrocatalytic behavior for the oxidation of ascorbic acid (AA) and reduction of nitrite ions.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ren Limei; Schuchardt, Frank; Shen Yujun

An absorbent mixture of magnesium hydroxide (Mg(OH){sub 2}) and phosphoric acid (H{sub 3}PO{sub 4}) was added to compost mixtures of pig manure with cornstalk in different molar ratios (T1, 1:1; T2, 1:2; T3, 1:3) in order to examine its effect on controlling ammonia losses during composting. Based on the principle of struvite precipitation, and with an unamended trial as control (CK), an in-vessel composting experiment was conducted in fermenters (60 L with forced aeration) in which the absorbent mixture was added with proportions of 3.8%, 7.3% and 8.9% of dry weight for T1, T2 and T3, respectively. The results showedmore » that the total nitrogen loss was reduced from 35% to 12%, 5% and 1% of initial N mass, respectively. In the final compost, the total nitrogen content in T1, T2 and T3 was improved by 10, 14, 12 g kg{sup -1}, and NH{sub 4}{sup +}-N in T1, T2 and T3 was improved by 8, 9, and 10 g kg{sup -1}, respectively, compared with the unamended trial. The results of the germination index test showed that the maturity of treatment T2 was best among the four treatments in the final compost, followed by T1, CK and T3. The results of X-ray diffraction (XRD) confirmed the formation of magnesium ammonium phosphate hexahydrate (MgNH{sub 4}PO{sub 4}.6H{sub 2}O:MAP) in the T1, T2 and T3 compost. Based on these results, the adsorbent mixture of Mg(OH){sub 2} + H{sub 3}PO{sub 4} could control nitrogen loss effectively during composting via struvite crystallization. However, an excess of phosphoric acid (1:3) had a negative influence on composting properties. The pH value decreased which led to reduced microorganism activity, and which finally resulted in reduced biodegradation of the organic matter.« less

Influence of ionic liquids on the syntheses and structures of Mn(II) coordination polymers based on multidentate N-heterocyclic aromatic ligands and bridging carboxylate ligands.

PubMed

Qin, Jian-Hua; Wang, Hua-Rui; Pan, Qi; Zang, Shuang-Quan; Hou, Hongwei; Fan, Yaoting

2015-10-28

Seven Mn(ii) coordination polymers, namely {[Mn2(ptptp)Cl2(H2O)3]·H2O}n (1), {[Mn(μ-ptptp)3]2[Mn3(μ3-Cl)]2}·2Cl·16H2O (2), {[Mn2(ptptp)(ip)2(H2O)3]·H2O}n (3), {[Mn2(ptptp)(5-CH3-ip)2(H2O)3]·H2O}n (4), {[Mn4(ptptp)(5-Br-ip)3(H2O)3]·4H2O}n (5), {[Mn2(ptptp)(Hbtc)(H2O)2]·2H2O}n (6) and {[Mn2(ptptp)(tdc)(H2O)2]·1.5H2O}n (7), have been prepared based on multidentate N-heterocyclic aromatic ligands and bridging carboxylate ligands (H2ptptp = 2-(5-{6-[5-(pyrazin-2-yl)-1H-1,2,4-triazol-3-yl]pyridin-2-yl}-1H-1,2,4-triazol-3-yl)pyrazine; R-isophthalic acids, H2ip-R: R = -H (3), -CH3 (4), -Br (5); H3btc = trimesic acid (6); H2tdc = thiophene-2,5-dicarboxylic acid (7)), in order to further probe the multiple roles of [RMI]Br ionic liquids in the hydro/solvothermal synthesis (RMI = 1-alkyl-3-methylimidazolium, R = ethyl, or propyl, or butyl). The successful syntheses of complexes 2-6 suggest that in hydro/solvothermal synthesis the addition of a small amount of [RMI]Br plays a crucial role. Complex 1 exhibits single right-handed helices constructed by ptptp ligands and Mn(ii) ions. Complex 2 possesses octanuclear helicate structures in which two propeller-shaped [Mn(μ-ptptp)3](4-) units embrace two [Mn3(μ3-Cl)](5+) cluster cores inside. Complexes 3 and 4 are isostructural and display a 1D double chain formed by two kinds of pseudo meso-helices: (Mn-ptptp)n and (Mn-5-R-ip)n. Complex 5 has a 2D structure containing 1D Mn(ii) ion chains formed through carboxylates and [ptptp](2-)-N,N bridges. Complex 6 shows a 2D structure formed by a meso-helix (Mn-ptptp)n and the partly deprotonated Hbtc ligands. Complex 7 features a heterochiral [2 + 2] coaxially nested double-helical column formed by using the outer double-helices (Mn-ptptp)n as a template to encapsulate the inner double-helices (Mn-tdc)n with opposite orientation. All complexes were characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, single-crystal X-ray crystallography and powder X-ray diffraction. The magnetic properties of 1-7 were also investigated.

Crystal structure and magnetic properties of a unique 3D coordination polymer constructed from flexible aliphatic tricarballylic acid ligands featuring linear trimeric Manganese(II)-based, metal carboxylate chains

NASA Astrophysics Data System (ADS)

Zou, Hua-Hong; Zhang, Shu-Hua; Zeng, Ming-Hua; Zhou, Yan-Ling; Liang, Hong

2008-08-01

A novel linear trimeric-based, Mn(II)-carboxylate chain well separated by long-linking flexible aliphatic tricarballylic acid ligands in a 3D coordination polymer [Mn 3(C 6H 5O 6) 2(H 2O) 4] n ( 1, C 6H 5O 6dbnd CH (COO -)(CH 2COO -) 2, TCA) exhibits low-dimensional antiferromagnetic order at 3.0 K. Such magnetic behavior is arises from the alternate Antiferro-Antiferro-Antiferro' ( J1J1J2) repeating interactions sequence, based on the nature of the binding modes of Mn(II)-carboxylate chain and the effect of interchains arrangement of 1. The reported carboxylate-bridged metal chain systems display a new structurally authenticated example of linear homometallic spin arranged antiferromagnet among metal carboxylates.

Copper-catalyzed formic acid synthesis from CO2 with hydrosilanes and H2O.

PubMed

Motokura, Ken; Kashiwame, Daiki; Miyaji, Akimitsu; Baba, Toshihide

2012-05-18

A copper-catalyzed formic acid synthesis from CO2 with hydrosilanes has been accomplished. The Cu(OAc)2·H2O-1,2-bis(diphenylphosphino)benzene system is highly effective for the formic acid synthesis under 1 atm of CO2. The TON value approached 8100 in 6 h. The reaction pathway was revealed by in situ NMR analysis and isotopic experiments.

Tris[(6S)-6-hy­droxy-4-epi-shikimic acid] monohydrate: an enanti­omerically pure hy­droxy­lated shikimic acid derived from methyl shikimate

PubMed Central

Griesbeck, Axel G.; Miara, Claus; Neudörfl, Jörg-M.

2012-01-01

The title compound, 3C7H10O6·H2O, is the enanti­omerically pure product of a multi-step synthesis from the enanti­omerically pure natural shikimic acid. The asymmetric unit contains three mol­ecules of the acid and one mol­ecule of water. The cyclo­hexene rings of the acids have half-chair conformations. The carboxyl­ate, the four hydroxide groups and the additional water mol­ecule form a complex three-dimensional hydrogen-bonding network. PMID:23284468

Two Dihydroxo-Bridged Plutonium(IV) Nitrate Dimers and Their Relevance to Trends in Tetravalent Ion Hydrolysis and Condensation

DOE PAGES

Knope, Karah E.; Skanthakumar, S.; Soderholm, L.

2015-10-13

We report the room temperature synthesis and structural characterization of a μ2-hydroxobridged PuIV dimer obtained from an acidic, nitric acid solution. The discrete Pu 2(OH) 2(NO 3) 6(H 2O) 4 moiety crystallized with two distinct crystal structures, (1) [Pu 2(OH) 2(NO 3) 6(H 2O) 4] 2·11H 2O and (2) Pu 2(OH) 2(NO 3) 6(H 2O) 4·2H 2O, which differ primarily in the number of incorporated water molecules. High-energy X-ray scattering (HEXS) data obtained from the mother liquor showed evidence of a correlation at 3.7(10) Å but only after concentration of the stock solution. This distance is consistent with the dihydroxo-bridgedmore » distance of 3.799(1) Å seen in the solid-state structure as well as with the known Pu-Pu distance in PuO 2. The structural characterization of a dihydroxo-bridged Pu moiety is discussed in terms of its relevance to the underlying mechanisms of tetravalent-metal-ion condensation« less

Spectra, energy levels, and energy transition of lanthanide complexes with cinnamic acid and its derivatives

NASA Astrophysics Data System (ADS)

Zhou, Kaining; Feng, Zhongshan; Shen, Jun; Wu, Bing; Luo, Xiaobing; Jiang, Sha; Li, Li; Zhou, Xianju

2016-04-01

High resolution spectra and luminescent lifetimes of 6 europium(III)-cinnamic acid complex {[Eu2L6(DMF)(H2O)]·nDMF·H2O}m (L = cinnamic acid I, 4-methyl-cinnamic acid II, 4-chloro-cinnamic acid III, 4-methoxy-cinnamic acid IV, 4-hydroxy-cinnamic acid V, 4-nitro-cinnamic acid VI; DMF = N, N-dimethylformamide, C3H7NO) were recorded from 8 K to room temperature. The energy levels of Eu3 + in these 6 complexes are obtained from the spectra analysis. It is found that the energy levels of the central Eu3 + ions are influenced by the nephelauxetic effect, while the triplet state of ligand is lowered by the p-π conjugation effect of the para-substituted functional groups. The best energy matching between the ligand triplet state and the central ion excited state is found in complex I. While the other complexes show poorer matching because the gap of 5D0 and triplet state contracts.

Uranium speciation in acid waste-weathered sediments: The role of aging and phosphate amendments

DOE PAGES

Perdrial, Nicolas; Vázquez-Ortega, Angélica; Wang, Guohui; ...

2017-12-05

Uranium speciation and lability are strongly coupled to mineral transformations in silicate sediments, particularly for sediments subjected to weathering in acidic, high-level radioactive waste, as occurred at the Department of Energy's Hanford (WA) site. Here, uncontaminated Hanford sediments were reacted for 365 days with acidic (pH 3), uranium-bearing waste solutions, with and without phosphate in batch experiments, prior to detailed characterizations using electron microscopy, x-ray diffraction and x-ray absorption spectroscopy. In PO 4-reactant free systems, uranium speciation was controlled initially by precipitation of compreignacite [K 2(UO 2) 6O 4(OH) 6·8H 2O]- and becquerelite [Ca(UO 2) 6O 4(OH) 6·8H 2O]-like species.more » Subsequent further removal of uranium coincided with that of Si and accumulation of boltwoodite, [(K, Na)(UO 2) 2O 4(HSiO 4) 2•0.5(H 2O)]-like species of uranium at 180 and 365 days. When present, PO 4 exerted a direct and strong control over U speciation. Furthermore, the detection of meta-ankoleite, [K 2(UO 2) 2O 4(PO 4) 2·6H 2O] at all reaction times when U was present emphasizes the importance of dissolved phosphate as a control on U speciation. Here, meta-ankoleite appears well crystallized and when it occurs as the principal product of sediment weathering, its low solubility is expected to limit dissolved U(VI) concentrations in groundwater. Although boltwoodite solubility is also low, it is formed more slowly (and only when PO 4 is absent), after initial precipitation of more soluble, less crystalline uranyl hydroxides. In the context of Hanford crib waste our results suggest that with PO 4 present, nearly all uranium would have precipitated in the upper soil.« less

Uranium speciation in acid waste-weathered sediments: The role of aging and phosphate amendments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Perdrial, Nicolas; Vázquez-Ortega, Angélica; Wang, Guohui

Uranium speciation and lability are strongly coupled to mineral transformations in silicate sediments, particularly for sediments subjected to weathering in acidic, high-level radioactive waste, as occurred at the Department of Energy's Hanford (WA) site. In this study, uncontaminated Hanford sediments were reacted for 365 days with acidic (pH 3), uranium-bearing waste solutions, with and without phosphate in batch experiments, prior to detailed characterizations using electron microscopy, x-ray diffraction and x-ray absorption spectroscopy. In PO(4)(-)reactant free systems, uranium speciation was controlled initially by precipitation of compreignacite [K-2(UO2)(6)O-4(OH)(6)center dot 8H(2)O]-and becquerelite [Ca(UO2)(6)O-4(OH)(6)center dot 8H(2)O]-like species. Subsequent further removal of uranium coincided withmore » that of Si and accumulation of boltwoodite, [(K, Na)(UO2)(2)O-4(HSiO4)(2)center dot 0.5(H2O)]-like species of uranium at 180 and 365 days. When present, PO4 exerted a direct and strong control over U speciation. The detection of meta-ankoleite, [K-2(UO2)(2)O-4(PO4)(2)center dot 6H(2)O] at all reaction times when U was present emphasizes the importance of dissolved phosphate as a control on U speciation. Here, meta-ankoleite appears well crystallized and when it occurs as the principal product of sediment weathering, its low solubility is expected to limit dissolved U(VI) concentrations in groundwater. Although boltwoodite solubility is also low, it is formed more slowly (and only when PO4 is absent), after initial precipitation of more soluble, less crystalline uranyl hydroxides. In the context of Hanford crib waste our results suggest that with PO4 present, nearly all uranium would have precipitated in the upper soil.« less

Uranium speciation in acid waste-weathered sediments: The role of aging and phosphate amendments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Perdrial, Nicolas; Vázquez-Ortega, Angélica; Wang, Guohui

Uranium speciation and lability are strongly coupled to mineral transformations in silicate sediments, particularly for sediments subjected to weathering in acidic, high-level radioactive waste, as occurred at the Department of Energy's Hanford (WA) site. Here, uncontaminated Hanford sediments were reacted for 365 days with acidic (pH 3), uranium-bearing waste solutions, with and without phosphate in batch experiments, prior to detailed characterizations using electron microscopy, x-ray diffraction and x-ray absorption spectroscopy. In PO 4-reactant free systems, uranium speciation was controlled initially by precipitation of compreignacite [K 2(UO 2) 6O 4(OH) 6·8H 2O]- and becquerelite [Ca(UO 2) 6O 4(OH) 6·8H 2O]-like species.more » Subsequent further removal of uranium coincided with that of Si and accumulation of boltwoodite, [(K, Na)(UO 2) 2O 4(HSiO 4) 2•0.5(H 2O)]-like species of uranium at 180 and 365 days. When present, PO 4 exerted a direct and strong control over U speciation. Furthermore, the detection of meta-ankoleite, [K 2(UO 2) 2O 4(PO 4) 2·6H 2O] at all reaction times when U was present emphasizes the importance of dissolved phosphate as a control on U speciation. Here, meta-ankoleite appears well crystallized and when it occurs as the principal product of sediment weathering, its low solubility is expected to limit dissolved U(VI) concentrations in groundwater. Although boltwoodite solubility is also low, it is formed more slowly (and only when PO 4 is absent), after initial precipitation of more soluble, less crystalline uranyl hydroxides. In the context of Hanford crib waste our results suggest that with PO 4 present, nearly all uranium would have precipitated in the upper soil.« less

Synthesis of Struvite using a Vertical Canted Reactor with Continuous Laminar Flow Process

NASA Astrophysics Data System (ADS)

Sutiyono, S.; Edahwati, L.; Muryanto, S.; Jamari, J.; Bayuseno, A. P.

2018-01-01

Struvite is a white crystalline that is chemically known as magnesium ammonium phosphorus hexahydrate (MgNH4PO4·6H2O). It can easily dissolve in acidic conditions and slightly soluble in neutral and alkaline conditions. In industry, struvite forms as a scale deposit on a pipe with hot flow fluid. However, struvite can be used as fertilizer because of its phosphate content. A vertical canted reactor is a promising technology for recovering phosphate levels in wastewater through struvite crystallization. The study was carried out with the vertical canted reactor by mixing an equimolar stock solution of MgCl2, NH4OH, and H3PO4 in 1: 1: 1 ratio. The crystallization process worked with the flow rate of three stock solution entering the reactor in the range of 16-38 ml/min, the temperature in the reactor is worked on 20°, 30°, and 40°C, while the incoming air rate is kept constant at 0.25 liters/min. Moreover, pH was maintained at a constant value of 9. The struvite crystallization process run until the steady state was reached. Then, the result of crystal precipitates was filtered and dried at standard temperature room for 48 hours. After that, struvite crystals were stored for the subsequent analysis by Scanning Electron Microscope (SEM) and XRD (X-Ray Diffraction) method. The use of canted reactor provided the high pure struvite with a prismatic crystal morphology.

MPK6 controls H2 O2-induced root elongation by mediating Ca2+ influx across the plasma membrane of root cells in Arabidopsis seedlings.

PubMed

Han, Shuan; Fang, Lin; Ren, Xuejian; Wang, Wenle; Jiang, Jing

2015-01-01

Mitogen-activated protein kinases (MPKs) play critical roles in signalling and growth, and Ca(2+) and H2 O2 control plant growth processes associated with abscisic acid (ABA). However, it remains unclear how MPKs are involved in H2 O2 - and Ca(2+) -mediated root elongation. Root elongation in seedlings of the loss-of-function mutant Atmpk6 (Arabidopsis thaliana MPK6) was less sensitive to moderate H2 O2 or ABA than that in wild-type (WT) plants. The enhanced elongation was a result of root cell expansion. This effect disappeared when ABA-induced H2 O2 accumulation or the cytosolic Ca(2+) increase were defective. Molecular and biochemical evidence showed that increased expression of the cell wall peroxidase PRX34 in Atmpk6 root cells enhanced apoplastic H2 O2 generation; this promoted a cytosolic Ca(2+) increase and Ca(2+) influx across the plasma membrane. The plasma membrane damage caused by high levels of H2 O2 was ameliorated in a Ca(2+) -dependent manner. These results suggested that there was intensified PRX34-mediated H2 O2 generation in the apoplast and increased Ca(2+) flux into the cytosol of Atmpk6 root cells; that is, the spatial separation of apoplastic H2 O2 from cytosolic Ca(2+) in root cells prevented H2 O2 -induced inhibition of root elongation in Atmpk6 seedlings. © 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.

Picric acid-2,4,6-trichloro-aniline (1/1).

PubMed

Wang, Wan-Qiang

2011-04-01

In the title adduct, C(6)H(4)Cl(3)N·C(6)H(3)N(3)O(7), the two benzene rings are almost coplanar, with a dihedral angle of 1.19 (1)° and an inter-ring centroid-centroid separation of 4.816 (2) Å. The crystal structure is stabilized by inter-molecular N-H⋯O(nitro) hydrogen bonds, giving a chain structure. In addition, there are phenol-nitro O-H⋯O inter-actions.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheng, Chiu Tung; Chan, Man Nin; Wilson, Kevin R.

Oxygenated organic molecules are abundant in atmospheric aerosols and are transformed by oxidation reactions near the aerosol surface by gas-phase oxidants such as hydroxyl (OH) radicals. To gain better insights into how the structure of an organic molecule, particularly in the presence of hydroxyl groups, controls the heterogeneous reaction mechanisms of oxygenated organic compounds, this study investigates the OH-radical initiated oxidation of aqueous tartaric acid (C 4 H 6 O 6 ) droplets using an aerosol flow tube reactor. The molecular composition of the aerosols before and after reaction is characterized by a soft atmospheric pressure ionization source (Direct Analysismore » in Real Time) coupled with a high-resolution mass spectrometer. The aerosol mass spectra reveal that four major reaction products are formed: a single C 4 functionalization product (C 4 H 4 O 6 ) and three C 3 fragmentation products (C 3 H 4 O 4 , C 3 H 2 O 4 , and C 3 H 2 O 5 ). The C 4 functionalization product does not appear to originate from peroxy radical self-reactions but instead forms via an α-hydroxylperoxy radical produced by a hydrogen atom abstraction by OH at the tertiary carbon site. The proximity of a hydroxyl group to peroxy group enhances the unimolecular HO 2 elimination from the α-hydroxylperoxy intermediate. This alcohol-to-ketone conversion yields 2-hydroxy-3-oxosuccinic acid (C 4 H 4 O 6 ), the major reaction product. While in general, C-C bond scission reactions are expected to dominate the chemistry of organic compounds with high average carbon oxidation states (OS C ), our results show that molecular structure can play a larger role in the heterogeneous transformation of tartaric acid (OS C = 1.5). These results are also compared with two structurally related dicarboxylic acids (succinic acid and 2,3-dimethylsuccinic acid) to elucidate how the identity and location of functional groups (methyl and hydroxyl groups) alter heterogeneous reaction mechanisms.« less

Exploring 3D non-interpenetrated metal-organic framework with malonate-bridged Co(II) coordination polymer: structural elucidation and theoretical study

NASA Astrophysics Data System (ADS)

Hossain, Anowar; Mandal, Tripti; Mitra, Monojit; Manna, Prankrishna; Bauzá, Antonio; Frontera, Antonio; Seth, Saikat Kumar; Mukhopadhyay, Subrata

2017-12-01

A Co(II)-based coordination polymer with tetranuclear cobalt(II)-malonate cluster has been easily generated by aqueous medium self-assembly from Cobalt(II) chloride hexahydrate and malonic acid. The structure exhibits a non-interpenetrating, highly undulating two-dimensional (2D) bi-layer network with (4,4) topology. The crystal structure is composed of infinite interdigitated 2D metal-organic bi-layers which extended to an intricate 3D framework through the interbilayer hydrogen bonds. We have studied energetically by means of Density Functional Theory (DFT) calculations the H-bonding interactions that connect the 2D metal-organic bi-layers. The finite theoretical models have been used to compute conventional O‒H•••O and unconventional C‒H•••O interactions which plays a key role to build 3D architecture.

Tetranuclear clusters containing a CrIII-doped MnIII4O2 core: syntheses, structures, and magnetic properties.

PubMed

Ma, Yun-Sheng; Li, Yi-Zhi; Song, You; Zheng, Li-Min

2008-06-02

The oxidation of MnII carboxylates by (NBu4)Cr2O7 in the presence of different phosphonic acids and chelating ligands results in six CrIII-doped tetranuclear manganese clusters formulated [Mn3CrO2(O2CCH3)4(O3PC5H4N)2(bpy)2] (1), [Mn3CrO2(O2CCH3)4(O3PC5H4N)2(phen)2] (2), [Mn3CrO2(O2CPh)4(O3PC5H4NO)2(phen)2] (3), [Mn3CrO2(O2CPh)4(O3PC6H11)2(bpy)2] (4), [Mn 3CrO2(O2CPh)4(O3PC6H11)2(phen) 2] (5), and [Mn3CrO2(O2CCH3)4(O3PC6H11)2(bpy)2] (6). Single-crystal X-ray analyses reveal that all the compounds contain similar [M4O2]8+ cores with the four metal sites arranged in planar topologies. The metal ions within the core are bridged by both carboxylate and phosphonate ligands. Temperature-dependent magnetic measurements show that in all cases dominant antiferromagnetic interactions are propagated between the metal centers. The ac magnetic measurements on compounds 5 and 6 reveal that both the in-phase and the out-of-phase signals are frequency dependent, characteristic of single-molecule magnet behaviors.

Crystal structure of 1-(3-chloro-phen-yl)piperazin-1-ium picrate-picric acid (2/1).

PubMed

Kavitha, Channappa N; Jasinski, Jerry P; Kaur, Manpreet; Anderson, Brian J; Yathirajan, H S

2014-11-01

The title salt {systematic name: bis-[1-(3-chloro-phen-yl)piperazinium 2,4,6-tri-nitro-phenolate]-picric acid (2/1)}, 2C10H14ClN2 (+)·2C6H5N3O7 (-)·C6H6N3O7, crystallized with two independent 1-(3-chloro-phen-yl)piperazinium cations, two picrate anions and a picric acid mol-ecule in the asymmetric unit. The six-membered piperazine ring in each cation adopts a slightly distorted chair conformation and contains a protonated N atom. In the picric acid mol-ecule, the mean planes of the nitro groups in the ortho-, meta-, and para-positions are twisted from the benzene ring by 31.5 (3), 7.7 (1), and 3.8 (2)°, respectively. In the anions, the dihedral angles between the benzene ring and the ortho-, meta-, and para-nitro groups are 36.7 (1), 5.0 (6), 4.8 (2)°, and 34.4 (9), 15.3 (8), 4.5 (1)°, respectively. The nitro group in one anion is disordered and was modeled with two sites for one O atom with an occupancy ratio of 0.627 (7):0.373 (7). In the crystal, the picric acid mol-ecule inter-acts with the picrate anion through a trifurcated O-H⋯O four-centre hydrogen bond involving an intra-molecular O-H⋯O hydrogen bond and a weak C-H⋯O inter-action. Weak inter-molecular C-H⋯O inter-actions are responsible for the formation of cation-anion-cation trimers resulting in a chain along [010]. In addition, weak C-H⋯Cl and weak π-π inter-actions [centroid-centroid distances of 3.532 (3), 3.756 (4) and 3.705 (3) Å] are observed and contribute to the stability of the crystal packing.

4-Nitro-aniline-picric acid (2/1).

PubMed

Li, Yan-Jun

2009-09-30

In the title adduct, C(6)H(3)N(3)O(7)·0.5C(6)H(6)N(2)O(2), the complete 4-nitro-aniline mol-ecule is generated by a crystallographic twofold axis with two C atoms and two N atoms lying on the axis. The mol-ecular components are linked into two dimensional corrugated layers running parallel to the (001) plane by a combination of inter-molecular N-H⋯O and C-H⋯O hydrogen bonds. The phenolic oxygen and two sets of nitro oxygen atoms in the picric acid were found to be disordered with occupancies of 0.81 (2):0.19 (2) and 0.55 (3):0.45 (3) and 0.77 (4):0.23 (4), respectively.

Synthesis of highly ordered TiO2 nanotube in malonic acid solution by anodization.

PubMed

Ryu, Won Hee; Park, Chan Jin; Kwon, Hyuk Sang

2008-10-01

We synthesized TiO2 nanotube array by anodizing in a solution of malonic acid (HOOCCH2COOH) and NH4F, and analyzed the morphology of the nanotube using scanning electron microscopy (SEM). The morphology of TiO2 nanotube was largely affected by anodizing time, anodizing voltage, and malonic acid concentration. With increasing the anodizing voltage from 5 V to 20 V, the diameter of TiO2 nanotube was increased from about 20 nm to 110 nm and its length from about 10 nm to 700 nm. In addition, the length of TiO2 nanotube was increased with increasing anodizing time up to 6 h at 20 V. We obtained the longest and the most highly ordered nanotube structure when anodizing Ti in a solution of 0.5 wt% NH4F and 1 M malonic acid at 20 V for 6 h.

Interaction of metal ions and amino acids - Possible mechanisms for the adsorption of amino acids on homoionic smectite clays

NASA Technical Reports Server (NTRS)

Gupta, A.; Loew, G. H.; Lawless, J.

1983-01-01

A semiempirical molecular orbital method is used to characterize the binding of amino acids to hexahydrated Cu(2+) and Ni(2+), a process presumed to occur when they are adsorbed in the interlamellar space of homoionic smectite clays. Five alpha-amino acids, beta-alanine, and gamma-aminobutyric acid were used to investigate the metal ion and amino acid specificity in binding. It was assumed that the alpha, beta, and gamma-amino acids would bind as bidentate anionic ligands, forming either 1:1 or 1:2 six-coordinated five, six, and seven-membered-ring chelate complexes, respectively. Energies of complex formation, optimized geometries, and electron and spin distribution were determined; and steric constraints of binding of the amino acids to the ion-exchanged cations in the interlamellar spacing of a clay were examined. Results indicate that hexahydrated Cu(2+) forms more stable complexes than hexahydrated Ni(2+) with all the amino acids studied. However, among these amino acids, complex formation does not favor the adsorption of the biological subset. Calculated energetics of complex formation and steric constraints are shown to predict that 1:1 rather than 1:2 metal-amino acid complexes are generally favored in the clay.

Plasticity of the Pyruvate Node Modulates Hydrogen Peroxide Production and Acid Tolerance in Multiple Oral Streptococci.

PubMed

Cheng, Xingqun; Redanz, Sylvio; Cullin, Nyssa; Zhou, Xuedong; Xu, Xin; Joshi, Vrushali; Koley, Dipankar; Merritt, Justin; Kreth, Jens

2018-01-15

Commensal Streptococcus sanguinis and Streptococcus gordonii are pioneer oral biofilm colonizers. Characteristic for both is the SpxB-dependent production of H 2 O 2 , which is crucial for inhibiting competing biofilm members, especially the cariogenic species Streptococcus mutans H 2 O 2 production is strongly affected by environmental conditions, but few mechanisms are known. Dental plaque pH is one of the key parameters dictating dental plaque ecology and ultimately oral health status. Therefore, the objective of the current study was to characterize the effects of environmental pH on H 2 O 2 production by S. sanguinis and S. gordonii S. sanguinis H 2 O 2 production was not found to be affected by moderate changes in environmental pH, whereas S. gordonii H 2 O 2 production declined markedly in response to lower pH. Further investigation into the pyruvate node, the central metabolic switch modulating H 2 O 2 or lactic acid production, revealed increased lactic acid levels for S. gordonii at pH 6. The bias for lactic acid production at pH 6 resulted in concomitant improvement in the survival of S. gordonii at low pH and seems to constitute part of the acid tolerance response of S. gordonii Differential responses to pH similarly affect other oral streptococcal species, suggesting that the observed results are part of a larger phenomenon linking environmental pH, central metabolism, and the capacity to produce antagonistic amounts of H 2 O 2 IMPORTANCE Oral biofilms are subject to frequent and dramatic changes in pH. S. sanguinis and S. gordonii can compete with caries- and periodontitis-associated pathogens by generating H 2 O 2 Therefore, it is crucial to understand how S. sanguinis and S. gordonii adapt to low pH and maintain their competitiveness under acid stress. The present study provides evidence that certain oral bacteria respond to environmental pH changes by tuning their metabolic output in favor of lactic acid production, to increase their acid survival, while others maintain their H 2 O 2 production at a constant level. The differential control of H 2 O 2 production provides important insights into the role of environmental conditions for growth competition of the oral flora. Copyright © 2018 American Society for Microbiology.

Effects of molten-salt/ionic-liquid mixture on extraction of docosahexaenoic acid (DHA)-rich lipids from Aurantiochytrium sp. KRS101.

PubMed

Choi, Sun-A; Jung, Joo-Young; Kim, Kyochan; Kwon, Jong-Hee; Lee, Jin-Suk; Kim, Seung Wook; Park, Ji-Yeon; Yang, Ji-Won

2014-11-01

In this study, lipid extraction from Aurantiochytrium sp. was performed using a molten-salt/ionic-liquid mixture. The total fatty acid content of Aurantiochytrium sp. was 478.8 mg/g cell, from which 145 mg/g cell (30.3% of total fatty acids) of docosahexaenoic acid (DHA) was obtained. FeCl3·6H2O showed a high lipid extraction yield (207.9 mg/g cell), when compared with that of [Emim]OAc, which was only 118.1 mg/g cell; notably however, when FeCl3·6H2O was mixed with [Emim]OAc (5:1, w/w), the yield was increased to 478.6 mg/g cell. When lipid was extracted by the FeCl3·6H2O/[Emim]OAc mixture at a 5:1 (w/w) blending ratio under 90 °C, 30 min reaction conditions, the fatty acid content of the extracted lipid was a high purity 997.7 mg/g lipid, with most of the DHA having been extracted (30.2% of total fatty acids). Overall, lipid extraction from Aurantiochytrium sp. was enhanced by the synergistic effects of the molten-salt/ionic-liquid mixture with different ions.

A novel ZrHIO6ṡ4H2O catalyst for degradation of organic dyes at room temperature

NASA Astrophysics Data System (ADS)

Li, Jiayin; Ma, Xinping; Qian, Meifan; Liu, Haoran; Liu, Qiying; Zhao, Caixian; Tian, Li; Chen, Lijuan; Tang, Jianting

It is interesting to obtain catalysts to degrade organic dye pollutants at room temperature for simultaneous purposes of environment-treating and energy-saving. In this work, a novel ZrHIO6ṡ4H2O catalyst was synthesized by reacting ZrO(NO3)2 with H5IO6 in aqueous nitric acid. The catalyst was found effective in degradation of rhodamine B (RhB) or methylene blue (MB) dyes at room temperature without light illumination. We used the ultraviolet-visible (UV-Vis) absorption spectra of dye solution as well as X-ray photoelectron spectroscopy (XPS) of ZrHIO6ṡ4H2O to confirm that the dye degradation was due to its catalytic role. Importantly, the ZrHIO6ṡ4H2O catalyst can be recycled five times without obvious activity loss and it achieved higher mineralization efficiency than the previously reported analogue in the degradation experiments.

Effects of pH on nitrogen transformations in media-based aquaponics.

PubMed

Zou, Yina; Hu, Zhen; Zhang, Jian; Xie, Huijun; Guimbaud, Christophe; Fang, Yingke

2016-06-01

To investigate the effects of pH on performance and nitrogen transformations in aquaponics, media-based aquaponics operated at pH 6.0, 7.5 and 9.0 were systematically examined and compared in this study. Results showed that nitrogen utilization efficiency (NUE) reached its maximum of 50.9% at pH 6.0, followed by 47.3% at pH 7.5 and 44.7% at pH 9.0. Concentrations of nitrogen compounds (i.e., TAN, NO2(-)-N and NO3(-)-N) in three pH systems were all under tolerable levels. pH had significant effect on N2O emission and N2O conversion ratio decreased from 2.0% to 0.6% when pH increased from 6.0 to 9.0, mainly because acid environment would inhibit denitrifiers and lead to higher N2O emission. 75.2-78.5% of N2O emission from aquaponics was attributed to denitrification. In general, aquaponics was suggested to maintain pH at 6.0 for high NUE, and further investigations on N2O mitigation strategy are needed. Copyright © 2016 Elsevier Ltd. All rights reserved.

Growth of SiO 2 on InP substrate by liquid phase deposition

NASA Astrophysics Data System (ADS)

Lei, Po Hsun; Yang, Chyi Da

2010-04-01

We have grown silicon dioxide (SiO 2) on indium phosphorous (InP) substrate by liquid phase deposition (LPD) method. With inserting InP wafer in the treatment solution composed of SiO 2 saturated hydrofluorosilicic acid (H 2SiF 6), 0.1 M boric acid (H 3BO 3) and 1.74 M diluted hydrochloric acid (HCl), the maximum deposition rate and refractive index for the as-grown LPD-SiO 2 film were about 187.5 Å/h and 1.495 under the constant growth temperature of 40 °C. The secondary ion mass spectroscope (SIMS) and energy dispersive X-ray (EDX) confirmed that the elements of silicon, oxygen, and chloride were found in the as-grown LPD-SiO 2 film. On the other hand, the effects of treatment solution incorporated with the hydrogen peroxide (H 2O 2) that can regulate the concentration of OH - ion were also shown in this article. The experimental results represented that the deposition rate decreases with increasing the concentration of hydrogen peroxide due to the reduced concentration of SiO 2 saturated H 2SiF 6 in treatment solution.

Hydration energies and structures of alkaline earth metal ions, M2+(H2O)n, n = 5-7, M = Mg, Ca, Sr, and Ba.

PubMed

Rodriguez-Cruz, S E; Jockusch, R A; Williams, E R

1999-09-29

The evaporation of water from hydrated alkaline earth metal ions, produced by electrospray ionization, was studied in a Fourier transform mass spectrometer. Zero-pressure-limit dissociation rate constants for loss of a single water molecule from the hydrated divalent metal ions, M(2+)(H(2)O)(n) (M = Mg, Ca, and Sr for n = 5-7, and M = Ba for n = 4-7), are measured as a function of temperature using blackbody infrared radiative dissociation. From these values, zero-pressure-limit Arrhenius parameters are obtained. By modeling the dissociation kinetics using a master equation formalism, threshold dissociation energies (E(o)) are determined. These reactions should have a negligible reverse activation barrier; therefore, E(o) values should be approximately equal to the binding energy or hydration enthalpy at 0 K. For the hepta- and hexahydrated ions at low temperature, binding energies follow the trend expected on the basis of ionic radii: Mg > Ca > Sr > Ba. For the hexahydrated ions at high temperature, binding energies follow the order Ca > Mg > Sr > Ba. The same order is observed for the pentahydrated ions. Collisional dissociation experiments on the tetrahydrated species result in relative dissociation rates that directly correlate with the size of the metals. These results indicate the presence of two isomers for hexahydrated magnesium ions: a low-temperature isomer in which the six water molecules are located in the first solvation shell, and a high-temperature isomer with the most likely structure corresponding to four water molecules in the inner shell and two water molecules in the second shell. These results also indicate that the pentahydrated magnesium ions have a structure with four water molecules in the first solvation shell and one in the outer shell. The dissociation kinetics for the hexa- and pentahydrated clusters of Ca(2+), Sr(2+), and Ba(2+) are consistent with structures in which all the water molecules are located in the first solvation shell.

Mixed-Ligand Uranyl Polyrotaxanes Incorporating a Sulfate/Oxalate Coligand: Achieving Structural Diversity via pH-Dependent Competitive Effect.

PubMed

Xie, Zhen-Ni; Mei, Lei; Hu, Kong-Qiu; Xia, Liang-Shu; Chai, Zhi-Fang; Shi, Wei-Qun

2017-03-20

A mixed-ligand system provides an alternative route to tune the structures and properties of metal-organic compounds by introducing functional organic or inorganic coligands. In this work, five new uranyl-based polyrotaxane compounds incorporating a sulfate or oxalate coligand have been hydrothermally synthesized via a mixed-ligand method. Based on C6BPCA@CB6 (C6BPCA = 1,1'-(hexane-1,6-diyl)bis(4-(carbonyl)pyridin-1-ium), CB6 = cucurbit[6]uril) ligand, UPS1 (UO 2 (L) 0.5 (SO 4 )(H 2 O)·2H 2 O, L = C6BPCA@CB6) is formed by the alteration of initial aqueous solution pH to a higher acidity. The resulting 2D uranyl polyrotaxane sheet structure of UPS1 is based on uranyl-sulfate ribbons connected by the C6BPCA@CB6 pseudorotaxane linkers. By using oxalate ligand instead of sulfate, four oxalate-containing uranyl polyrotaxane compounds, UPO1-UPO4, have been acquired by tuning reaction pH and ligand concentration: UPO1 (UO 2 (L) 0.5 (C 2 O 4 ) 0.5 (NO 3 )·3H 2 O) in one-dimensional chain was obtained at a low pH value range (1.47-1.89) and UPO2 (UO 2 (L)(C 2 O 4 )(H 2 O)·7H 2 O)obtained at a higher pH value range (4.31-7.21). By lowering the amount of oxalate, another two uranyl polyrotaxane network UPO3 ((UO 2 ) 2 (L) 0.5 (C 2 O 4 ) 2 (H 2 O)) and UPO4 ((UO 2 ) 2 O(OH)(L) 0.5 (C 2 O 4 ) 0.5 (H 2 O)) could be acquired at a low pH value of 1.98 and a higher pH value over 6, respectively. The UPO1-UPO4 compounds, which display structural diversity via pH-dependent competitive effect of oxalate, represent the first series of mixed-ligand uranyl polyrotaxanes with organic ligand as the coligand. Moreover, the self-assembly process and its internal mechanism concerning pH-dependent competitive effect and other related factors such as concentration of the reagents and coordination behaviors of the coligands were discussed in detail.

5-Arylidene derivatives of Meldrum's acid: Synthesis, structural characterization using single crystal and powder crystal X-ray diffraction, and electronic properties

NASA Astrophysics Data System (ADS)

Dey, Tanusri; Ghosh, Soumen; Ghosh, Somnath; Mukherjee, Alok Kumar

2015-07-01

Four 5-arylidene derivatives of Meldrum's acid, 5-(4-chlorobenzylidene)-2,2-dimethyl-1,3-dioxane-4,6-dione (2), 5-(3-hydroxybenzylidene)-2,2-dimethyl-1,3-dioxane-4,6-dione (3), 5-(3,4-dimethoxybenzylidene)-2,2-dimethyl-1,3-dioxane-4,6-dione (4) and 5-(2,4-dimethoxy benzylidene)-2,2-dimethyl-1,3-dioxane-4,6-dione (5) have been synthesized and their crystal structures have been determined using single crystal X-ray diffractometry for 2, 4 and 5 and X-ray powder diffraction for 3. The nature of intermolecular interactions in 2-5 has been analyzed through Hirshfeld surfaces and 2D fingerprint plots. The DFT optimized molecular geometries in 2-5 agree closely with those obtained from the crystallographic studies. The crystal packing in 2-5 exhibits an interplay of Osbnd H⋯O, Csbnd H⋯O, Csbnd H⋯Cl and Csbnd H⋯π (arene) hydrogen bonds and π⋯π interactions, which assemble molecules into three-dimensional architecture in 2, 3 and 5 and two-dimensional framework in 4. The Hirshfeld surface analyses of 2-5, Meldrum's acid (1) and a few related 5-arylidene derivatives of Meldrum's acid retrieved from the Cambridge Structural Database (CSD) indicate that about 85% of the Hirshfeld surface area (72% in 2 where H⋯Cl contribution is about 13%) in this class of compounds are due to H⋯H, O⋯H and C⋯H contacts. The HOMO-LUMO energy gap (>2.2 eV) in 2-5 indicates a significant degree of internal charge transfer within the molecule.

Synthesis, characterization and biological activities of metal(II) dipicolinate complexes derived from pyridine-2,6-dicarboxylic acid and 2-(piperazin-1-yl)ethanol

NASA Astrophysics Data System (ADS)

Büyükkıdan, Nurgün; Yenikaya, Cengiz; İlkimen, Halil; Karahan, Ceyda; Darcan, Cihan; Korkmaz, Tülin; Süzen, Yasemin

2015-12-01

The new water-soluble and air stable compounds (H2ppz)[Co(dipic)2]·6H2O (1), (H2ppz)[Ni(dipic)2]·6H2O (2) and (H2ppz)[Zn(dipic)2]·6H2O (3) were prepared by the reaction of corresponding metal(II) acetates and a proton transfer salt, (H2ppz) (Hdipic)2, (4) of pyridine-2,6-dicarboxylic acid (H2dipic) and 2-(piperazin-1-yl)ethanol (ppz). The compounds 1-3 were characterized by elemental, IR, UV-vis. thermal analyses, magnetic measurement and single crystal X-ray diffraction studies. The molecular structures of the title compounds consist of one 1-(2-hydroxyethyl)piperazine-1,4-diium (H2ppz+2) cation, one bis(pyridine-2,6-dicarboxylate)metal(II) [M(dipic)2]2- anion, and six uncoordinated water molecules. In compounds 1-3 the metal ions coordinate to two oxygen and one nitrogen atoms of two pyridine-2,6-dicarboxylate molecules forming an octahedral environment. Antimicrobial activities against Gram (-) wild type (Escherichia coli and Pseudomonas aeruginosa), Gram (+) wild type (Staphylococcus aureus, Staphylococcus epidermidis, Bacillus cereus and Bacillus subtilis) and clinical isolate (Morganella morganii, Proteus vulgaris and Enterobacter aeruginosa) were also studied. The results were reported, discussed and compared with the corresponding starting materials ((H2ppz) (Hdipic)2 (4), H2dipic and ppz). MIC (Minimal Inhibition Concentration) values of the newly synthesized compounds were determined as 4000 μg/ml (except B. subtilis and clinical isolate E. aeruginosa, >4000 μg/ml).

Measurements of radiological data of some amino acids in the energy range 0.122-1.330MeV

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lokhande, Rajkumar M., E-mail: rajml358@gmail.com; More, Chaitali V.; Surung, Bharat S.

Radiological parameters such as μ{sub m}, σ{sub t}, σ{sub e}, Z{sub eff} and N{sub eff} of amino acids, namely Lysine (C{sub 6}H{sub 15}N{sub 2}O{sub 2}), Histidine (C{sub 6}H{sub 9}N{sub 3}O{sub 2}) and Arginine (C{sub 6}H{sub 15}N{sub 4}O{sub 2}), were measured using NaI (Tl)-based gamma spectrometry. Radioactive sources used in the study are {sup 57}Co, {sup 133}Ba, {sup 137}Cs, {sup 54}Mn, {sup 60}Co and {sup 22}Na. Gamma ray transmission method in a narrow beam good geometry set up was used in the study. The measured data were compared against XCOM-based data. The agreement is within 2%.

Facile Approach to Preparing a Vanadium Oxide Hydrate Layer as a Hole-Transport Layer for High-Performance Polymer Solar Cells.

PubMed

Cong, Hailin; Han, Dongwei; Sun, Bingbing; Zhou, Dongying; Wang, Chen; Liu, Ping; Feng, Lai

2017-05-31

We demonstrate a facile and green approach to preparing a vanadium oxide hydrate (VO x ·nH 2 O) layer to serve as the hole-transport layer (HTL) in high-performance polymer solar cells (PSCs). The VO x ·nH 2 O layer was in situ prepared by a combined H 2 O 2 and ultraviolet-ozone (UVO) processing on a VO x layer. The as-prepared VO x ·nH 2 O layer featured a work function of 5.0 ± 0.1 eV, high transmittance, and better interface properties compared to those of the generally prepared VO x (UVO or thermal annealing) layers. PSCs based on poly[(ethylhexyl-thiophenyl)-benzodithiophene-(ethylhexyl)-thienothiophene]/[6,6]-phenyl-C 71 -butyric acid methyl ester using the VO x ·nH 2 O layer as the HTL yielded high power conversion efficiencies (PCEs) up to 8.11%, outperforming the devices with VO x layers (PCE of 6.79% for the UVO-processed VO x layer and 6.10% for the thermally annealed VO x layer) and conventional polyethylenedioxythiophene-polystyrenesulfonate (PEDOT:PSS) layers (PCE of 7.67%). The improved PCE was attributed to the enhanced J SC and/or fill factor, which mainly correlate to the improved interfacial contact between the photoactive layer and the indium tin oxide/HTL or cathode when using the VO x ·nH 2 O layer as the HTL. A similar improvement in the PCE was also observed for the PSCs based on poly(3-hexylthiophene)/[6,6]-phenyl-C 61 -butyric acid methyl ester. In addition, PSCs with a VO x ·nH 2 O layer as the HTL showed a higher stability than that of those with a PEDOT:PSS layer. Hence, it would be possible to use this simply and in situ prepared VO x ·nH 2 O layer as an inexpensive HTL for high-performance PSCs.

Structures and standard molar enthalpies of formation of a series of Ln(III)–Cu(II) heteronuclear compounds with pyrazine-2,3-dicarboxylic acid

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Qi; Xie, Gang; Wei, Qing

2014-07-01

Fifteen lanthanide–copper heteronuclear compounds, formulated as [CuLn{sub 2}(pzdc){sub 4}(H{sub 2}O){sub 6}]·xH{sub 2}O (1–6(x=2), 8(x=3), 9–10(x=4)); [CuLn{sub 2}(pzdc){sub 4}(H{sub 2}O){sub 4}]·xH{sub 2}O (7, 12–13, 15(x=4), 14(x=5), 11(x=8)) (Ln(III)=La(1); Ce(2); Pr(3); Nd(4); Sm(5); Eu(6); Gd(7); Tb(8); Dy(9); Ho(10); Er(11); Tm(12); Yb(13); Lu(14); Y(15); H{sub 2}pzdc (C{sub 6}H{sub 4}N{sub 2}O{sub 4})=pyrazine-2,3-dicarboxylic acid) have been hydrothermally synthesized. All compounds were characterized by element analysis, IR spectroscopy, single-crystal X-ray diffraction and thermal analysis. X-ray diffraction analyses confirm that all compounds are isostructural and feature a 3D brick-like framework structure with (4.6{sup 2}){sub 2}(4{sup 2}.6{sup 2}.8{sup 2})(6{sup 3}){sup 2}(6{sup 5}.8){sub 2} topology. Using 1 mol cm{supmore » −3} HCl(aq) as calorimetric solvent, with an isoperibol solution–reaction calorimeter, the standard molar enthalpies of formation of all compounds were determined by a designed thermochemical cycle. In addition, solid state luminescence properties of compounds 5, 6, 8 and 9 were studied in the solid state. - Graphical abstract: According to Hess' rule, the standard molar enthalpies of formation of Ln–Cu heterometallic coordination compounds were determined by a designed thermochemical cycle. - Highlights: • Fifteen lanthanide–copper heteronuclear isostructural compounds. • Structurally characterization by IR, X-ray diffraction and thermal analysis. • The standard molar enthalpy of formation. • Isoperibol solution–reaction calorimetry.« less

Influence of the Organic Species and Oxoanion in the Synthesis of two Uranyl Sulfate Hydrates, (H 3 O) 2 [(UO 2 ) 2 (SO 4 ) 3 ­(H 2 O)]·7H 2 O and (H 3 O) 2 [(UO 2 ) 2 (SO 4 ) 3 (H 2 O)]·4H 2 O, and a Uranyl Selenate-Selenite [C 5 H 6 N][(UO 2 )(SeO 4 )(HSeO 3 )

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jouffret, Laurent J.; Wylie, Ernest M.; Burns, Peter C.

2012-08-08

Two uranyl sulfate hydrates, (H3O)2[(UO2)2(SO4)3(H2O)]·7H2O (NDUS) and (H3O)2[(UO2)2(SO4)3(H2O)]·4H2O (NDUS1), and one uranyl selenate-selenite [C5H6N][(UO2)(SeO4)(HSeO3)] (NDUSe), were obtained and their crystal structures solved. NDUS and NDUSe result from reactions in highly acidic media in the presence of L-cystine at 373 K. NDUS crystallized in a closed vial at 278 K after 5 days and NDUSe in an open beaker at 278 K after 2 weeks. NDUS1 was synthesized from aqueous solution at room temperature over the course of a month. NDUS, NDUS1, and NDUSe crystallize in the monoclinic space group P21/n, a = 15.0249(4) Å,b = 9.9320(2) Å, c = 15.6518(4)more » Å, β = 112.778(1)°, V = 2153.52(9) Å3,Z = 4, the tetragonal space group P43212, a = 10.6111(2) Å,c = 31.644(1) Å, V = 3563.0(2) Å3, Z = 8, and in the monoclinic space group P21/n, a = 8.993(3) Å, b = 13.399(5) Å, c = 10.640(4) Å,β = 108.230(4)°, V = 1217.7(8) Å3, Z = 4, respectively.The structural units of NDUS and NDUS1 are two-dimensional uranyl sulfate sheets with a U/S ratio of 2/3. The structural unit of NDUSe is a two-dimensional uranyl selenate-selenite sheets with a U/Se ratio of 1/2. In-situ reaction of the L-cystine ligands gives two distinct products for the different acids used here. Where sulfuric acid is used, only H3O+ cations are located in the interlayer space, where they balance the charge of the sheets, whereas where selenic acid is used, interlayer C5H6N+ cations result from the cyclization of the carboxyl groups of L-cystine, balancing the charge of the sheets.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Yingjie, E-mail: yzx@ansto.gov.au; Bhadbhade, Mohan; Karatchevtseva, Inna

Three new coordination polymers of uranium(VI) with pyromellitic acid (H{sub 4}btca) have been synthesized and structurally characterized. (ED)[(UO{sub 2})(btca)]·(DMSO)·3H{sub 2}O (1) (ED=ethylenediammonium; DMSO=dimethylsulfoxide) has a lamellar structure with intercalation of ED and DMSO. (NH{sub 4}){sub 2}[(UO{sub 2}){sub 6}O{sub 2}(OH){sub 6}(btca)]·~6H{sub 2}O (2) has a 3D framework built from 7-fold coordinated uranyl trinuclear units and btca ligands with 1D diamond-shaped channels (~8.5 Å×~8.6 Å). [(UO{sub 2}){sub 2}(H{sub 2}O)(btca)]·4H{sub 2}O (3) has a 3D network constructed by two types of 7-fold coordinated uranium polyhedron. The unique μ{sub 5}-coordination mode of btca in 3 enables the formation of 1D olive-shaped large channels (~4.5more » Å×~19 Å). Vibrational modes, thermal stabilities and fluorescence properties have been investigated. - Graphical abstract: Table of content: three new uranium(VI) coordination polymers with pyromellitic acid (H{sub 4}btca) have been synthesized via room temperature and hydrothermal synthesis methods, and structurally characterized. Two to three dimensional (3D) frameworks are revealed. All 3D frameworks have unique 1D large channels. Their vibrational modes, thermal stabilities and photoluminescence properties have been investigated. - Highlights: • Three new coordination polymers of U(VI) with pyromellitic acid (H{sub 4}btca). • Structures from a 2D layer to 3D frameworks with unique 1D channels. • Unusual µ{sub 5}-(η{sub 1}:η{sub 2}:η{sub 1}:η{sub 2:}η{sub 1}) coordination mode of btca ligand. • Vibrational modes, thermal stabilities and luminescent properties reported.« less

A pair of novel Cd(II) enantiomers based on lactate derivatives: Synthesis, crystal structures and properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Zhong-Xuan, E-mail: xuzhongxuan1974@163.com; State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, the Chinese Academy of Sciences, Fuzhou, Fujian 350002; Ao, Ke-Hou

A pair of novel 3D homochiral metal−organic frameworks (HMOFs), namely [Cd{sub 2.5}((R)-CIA){sub 6}(1,4-DIB)(H{sub 2}O){sub 2}]·((CH{sub 3}){sub 2}NH{sub 2})·H{sub 2}O (1-D), [Cd{sub 2.5}((S)-CIA){sub 6}(1,4-DIB)(H{sub 2}O){sub 2}]·((CH{sub 3}){sub 2}NH{sub 2})·H{sub 2}O (1-L), have been synthesized using lactic acid derivative ligands ((R)-H{sub 3}CIA and (S)-H{sub 3}CIA) and 1,4-DIB. Crystallographic analyses indicate that the complexes 1-D and 1-L are packed by cage substructures. Some physical characteristics, such as solid-state circular dichroism (CD), thermal stabilities and photoluminescent properties are also investigated. Our results highlight the effective method to apply lactic acid derivative ligands to form interesting HMOFs. - Graphical abstract: Using lactic acid derivative ligandsmore » ((R)-H{sub 3}CIA and (S)-H{sub 3}CIA) and 1,4-DIB to assemble with Cd{sup 2+} ions, a pair of novel 3D homochiral metal-organic frameworks (HMOFs) with cage substructures have been synthesized. Display Omitted - Highlights: • Lactic acid derivative ligands • Cage substructure • Enantiomers.« less

Vitamin C: an experimental and theoretical study on the gas-phase structure and ion energetics of protonated ascorbic acid.

PubMed

Ricci, Andreina; Pepi, Federico; Cimino, Paola; Troiani, Anna; Garzoli, Stefania; Salvitti, Chiara; Di Rienzo, Brunella; Barone, Vincenzo

2016-12-01

In order to investigate the gas-phase mechanisms of the acid catalyzed degradation of ascorbic acid (AA) to furan, we undertook a mass spectrometric (ESI/TQ/MS) and theoretical investigation at the B3LYP/6-31 + G(d,p) level of theory. The gaseous reactant species, the protonated AA, [C 6 H 8 O 6 ]H + , were generated by electrospray ionization of a 10 -3  M H 2 O/CH 3 OH (1 : 1) AA solution. In order to structurally characterize the gaseous [C 6 H 8 O 6 ]H + ionic reactants, we estimated the proton affinity and the gas-phase basicity of AA by the extended Cooks's kinetic method and by computational methods at the B3LYP/6-31 + G(d,p) level of theory. As expected, computational results identify the carbonyl oxygen atom (O2) of AA as the preferred protonation site. From the experimental proton affinity of 875.0 ± 12 kJ mol -1 and protonation entropy ΔS p 108.9 ± 2 J mol -1  K -1 , a gas-phase basicity value of AA of 842.5 ± 12 kJ mol -1 at 298 K was obtained, which is in agreement with the value issuing from quantum mechanical computations. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Line shape of 57Co sources exhibiting self absorption

NASA Astrophysics Data System (ADS)

Spiering, H.; Ksenofontov, V.; Leupold, O.; Kusz, J.; Deák, L.; Németh, Z.; Bogdán, C.; Bottyán, L.; Nagy, D. L.

2016-12-01

The effect of selfabsorption in Mössbauer sources is studied in detail. Spectra were measured using an old 57 C o/ R h source of 74 M B q activity with an original activity of ca. 3.7 G B q and a 0.15 G B q 57 C o/ α - F e source magnetized by an in-plane magnetic field of 0.2 T. The 57 C o/ α - F e source of a thickness of 25 μ was used both from the active and the inactive side giving cause to very different selfabsorption effects. The absorber was a single crystal of ferrous ammonium sulphate hexahydrate (FAS). Its absorption properties were taken over from a detailed study (Bull et al., Hyperfine Interact. 94(1-3), 1; Spiering et al. 2). FAS (space group P21/c) crystallizes as flat plates containing the (overline {2}01) plane. The γ-direction was orthogonal to the crystal plate. The 57 C o atoms of the 57 C o/ R h source were assumed to be homogeneously distributed over a 6 μ thick Rh foil and to follow a one dimensional diffusion profile in the 25 μ Fe-foil. The diffusion length was fitted to 10 μ. The theory follows the Blume-Kistner equations for forward scattering (Blume and Kistner, Phys. Rev. 171, 417, 3) by integrating over the source sampled up to 128 layers.

Effects of supplementing different ratios of omega-3 and omega-6 fatty acids in western-style diets on cow's milk protein allergy in a mouse model.

PubMed

Thang, Cin L; Boye, Joyce I; Shi, Hai Ning; Zhao, Xin

2013-11-01

This study investigated the effects of supplementing different ratios of omega-6 and omega-3 fatty acids (O6H = 10:1, O3O6 = 4:1, and O3H = 1:4) to western-style diets on cow β-lactoglobulin (BLG) induced allergic reactions in Balb/c mice. Three-week-old mice were randomly assigned to three diet groups (n = 20/group). At 9 wk of age, half of the mice from each dietary treatment (n = 10) were intraperitoneally (i.p.) sensitized with three weekly doses of BLG and alum while the remaining half from each group was sham sensitized (controls). One week after the final sensitization, all mice were orally challenged with BLG. Elevated BLG-specific serum Igs were observed in all sensitized and challenged mice. IFN-γ, MCP-1, and IL-12p40 concentrations from lymphocytes of mesenteric lymph nodes were highest in O3H mice, compared to O3O6 and O6H mice. O6H mice had the highest IL-4 concentrations from splenic lymphocytes and a significantly lower rectal temperature after the challenge in comparison to O3O6 and O3H mice. Our results suggest that the ω-3 PUFA rich diets alleviated the severity of allergic reactions, and may modulate immune response toward T helper cell (Th)1-favoured immune response while the ω-6 PUFA rich diet exhibited no allergy alleviation with a stronger Th2 polarized immune response. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Insensitive High-Performance Replacements for RDX in Explosive and Propellant Formulations

DTIC Science & Technology

2007-03-16

1) was prepared in good yield and purity from 3,4,5- triamino-1,2,4-triazole (guanazine) and picric acid (eq. 1, see experimental). C2H6N6...g (5 mmol) of 3,4,5-triamino-1,2,4-triazole (prepared as described in the literature [6]) was added 1.15 g of picric acid (1 wt.% in H2O from...hydrobromic acid in MeOH. A white solid precipitated, was filtered off and washed with a saturated solution of sodium carbonate in cold water. It was

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Zhi-Hao; Zhao, Yue; Chen, Shui-Sheng

Seven new coordination polymers [Zn(H{sub 2}L)(mbdc)] (1), [Zn(H{sub 3}L)(btc)] (2), [Zn(H{sub 2}L)(Hbtc)] (3), [Zn(H{sub 2}L)(Hbtc)]·H{sub 2}O (4), [Zn{sub 2}(H{sub 2}L)(btc)(μ{sub 2}-OH)] (5), [Cd(H{sub 2}L)(mbdc)] (6) and [Cd{sub 3}(H{sub 2}L){sub 2}(btc){sub 2}(H{sub 2}O)]·5H{sub 2}O (7) were synthesized by reactions of the corresponding metal salt with rigid ligand 1,3-di(1H-imidazol-4-yl)benzene (H{sub 2}L) and different carboxylic acids of 1,3-benzenedicarboxylic acid (H{sub 2}mbdc) and benzene-1,3,5-tricarboxylic acid (H{sub 3}btc), respectively. The results of X-ray crystallographic analysis indicate that complex 1 is 1D chain while 2 is a (3,3)-connected 2D network with Point (Schläfli) symbol of (4,8{sup 2}). Complexes 3 and 6 are 2D networks, 4 ismore » a 3-fold interpenetrating 3D framework with Point (Schläfli) symbol of (6{sup 5},8) and 5 is a (3,8)-connected 2D network with Point (Schläfli) symbol of (3,4{sup 2}){sub 2}(3{sup 4},4{sup 6},5{sup 6},6{sup 8},7{sup 3},8), while 7 is a (3,10)-connected 3D net with Schläfli symbol of (3,4,5){sub 2}(3{sup 4},4{sup 8},5{sup 18},6{sup 12},7{sup 2},8). The thermal stability and photoluminescence of the complexes were investigated. Furthermore, DFT calculations were performed for 2–4 to discuss the temperature controlled self-assembly of the complexes. - Graphical abstract: Seven new coordination polymers with multicarboxylate and rigid ditopic 4-imidazole containing ligands have been obtained and found to show different structures and topologies. - Highlights: • Metal complexes with diverse structures of 1D chain, 2D network and 3D framework. • Mixed ligands of 1,3-di(1H-imidazol-4-yl)benzene and multicarboxylate. • Photoluminescence property.« less

Crystal structures of two 6-(2-hy-droxy-benzo-yl)-5H-thia-zolo[3,2-a]pyrimidin-5-ones.

PubMed

Gomes, Ligia R; Low, John Nicolson; Cagide, Fernando; Borges, Fernanda

2015-07-01

The title compounds, 6-(2-hy-droxy-benz-yl)-5H-thia-zolo[3,2-a]pyrimidin-5-one, C13H8N2O3S, (1), and 6-(2-hy-droxy-benz-yl)-3-methyl-5H-thia-zolo[3,2-a]pyrimidin-5-one, C14H10N2O3S, (2), were synthesized when a chromone-3-carb-oxy-lic acid, activated with (benzotriazol-1-yl-oxy)tripyrrolidinyl-phospho-nium hexa-fluorido-phosphate (PyBOP), was reacted with a primary heteromamine. Instead of the expected amidation, the unusual title thia-zolo-pyrimidine-5-one derivatives were obtained serendipitously and a mechanism of formation is proposed. Both compounds present an intra-molecular O-H⋯O hydrogen bond, which generates an S(6) ring. The dihedral angles between the heterocyclic moiety and the 2-hydroxybenzoyl ring are 55.22 (5) and 46.83 (6)° for (1) and (2), respectively. In the crystals, the mol-ecules are linked by weak C-H⋯O hydrogen bonds and π-π stacking inter-actions.

Unique (3,8)-connected lanthanide arenedisulfonate metal-organic frameworks containing benzimidazole-5,6-dicarboxylic acid co-ligand: Syntheses, structures and luminescence

NASA Astrophysics Data System (ADS)

Sun, Yan-Qiong; Liu, Qi; Zhong, Jie-Cen; Pan, Qun-Feng; Chen, Yi-Ping

2013-10-01

Two isostructural 3D lanthanide arenedisulfonate metal-organic frameworks (MOFs) [Ln(Hbidc)(nds)0.5(H2O)]n(Ln=Eu(1), La(2)) have been successfully synthesized by the hydrothermal reaction of lanthanide oxide with 2,6-naphthalenedisulfonate sodium (Na2nds) and an auxiliary ligand, 1H-benzimidazole-5,6-dicarboxylic acid (H3bidc). The two complexes are both constructed from 2D [Ln(Hbidc)]+ double layers pillared by nds2- ligands to generate 3D (3, 8)-connected open-framework structures with 1D long narrow channels running along the a axis. From topological point of view, the 3D framework is a (3, 8)-connected tfz-d net. The weak interactions including N-H⋯O, O-H⋯O hydrogen bonds and π-π stacking are observed in 1. The 2D IR correlation spectroscopy was applied to study the molecular interactions induced by thermal perturbation. The emission spectra of 1 exhibit the characteristic transition of 5D0→7FJ(J=0-4) of Eu(III).

The oxidation of 2,6-di-tert-butyl-4-methylphenol

USGS Publications Warehouse

Yohe, G.R.; Dunbar, J.E.; Pedrotti, R.L.; Scheidt, F.M.; Lee, F.G.H.; Smith, E.C.

1956-01-01

The products formed in the oxidation of 2,6-di-tert-butyl-4-methylphenol with oxygen and sodium hydroxide at about 100?? are 3,5-di-tert-butyl-4-hydroxybenzaldehyde, trimethylacetic acid, an acidic compound C14H22O3, and probably 2,6-di-tert-butylbenzoquinone (which was actually isolated in the similar oxidation of the above-named benzaldehyde), in addition to compounds previously reported. Some of the properties of C14H22O3 are given, and the oxidation of it to 2,3-di-tert-butylsuccinic anhydride is described, but assignment of structure is reserved pending the completion of more experimental work.

Two-dimensional 3d-4f heterometallic coordination polymers: syntheses, crystal structures, and magnetic properties of six new Co(II)-Ln(III) compounds.

PubMed

Díaz-Gallifa, Pau; Fabelo, Oscar; Pasán, Jorge; Cañadillas-Delgado, Laura; Lloret, Francesc; Julve, Miguel; Ruiz-Pérez, Catalina

2014-06-16

Six new heterometallic cobalt(II)-lanthanide(III) complexes of formulas [Ln(bta)(H2O)2]2[Co(H2O)6]·10H2O [Ln = Nd(III) (1) and Eu(III) (2)] and [Ln2Co(bta)2(H2O)8]n·6nH2O [Ln = Eu(III) (3), Sm(III) (4), Gd(III) (5), and Tb(III) (6)] (H4bta = 1,2,4,5-benzenetretracaboxylic acid) have been synthesized and characterized via single-crystal X-ray diffraction. 1 and 2 are isostructural compounds with a structure composed of anionic layers of [Ln(bta)(H2O)2]n(n-) sandwiching mononuclear [Co(H2O)6](2+) cations plus crystallization water molecules, which are interlinked by electrostatic forces and hydrogen bonds, leading to a supramolecular three-dimensional network. 3-6 are also isostructural compounds, and their structure consists of neutral layers of formula [Ln2Co(bta)2(H2O)8]n and crystallization water molecules, which are connected through hydrogen bonds to afford a supramolecular three-dimensional network. Heterometallic chains formed by the regular alternation of two nine-coordinate lanthanide(III) polyhedra [Ln(III)O9] and one compressed cobalt(II) octahedron [Co(II)O6] along the crystallographic c-axis are cross-linked by bta ligands within each layer of 3-6. Magnetic susceptibility measurements on polycrystalline samples for 3-6 have been carried out in the temperature range of 2.0-300 K. The magnetic behavior of these types of Ln(III)-Co(II) complexes, which have been modeled by using matrix dagonalization techniques, reveals the lack of magnetic coupling for 3 and 4, and the occurrence of weak antiferromagnetic interactions within the Gd(III)-Gd(III) (5) and Tb(III)-Tb(III) (6) dinuclear units through the exchange pathway provided by the double oxo(carboxylate) and double syn-syn carboxylate bridges.

Importance of Unimolecular HO 2 Elimination in the Heterogeneous OH Reaction of Highly Oxygenated Tartaric Acid Aerosol

DOE PAGES

Cheng, Chiu Tung; Chan, Man Nin; Wilson, Kevin R.

2016-07-09

Oxygenated organic molecules are abundant in atmospheric aerosols and are transformed by oxidation reactions near the aerosol surface by gas-phase oxidants such as hydroxyl (OH) radicals. To gain better insights into how the structure of an organic molecule, particularly in the presence of hydroxyl groups, controls the heterogeneous reaction mechanisms of oxygenated organic compounds, this paper investigates the OH-radical initiated oxidation of aqueous tartaric acid (C 4H 6O 6) droplets using an aerosol flow tube reactor. The molecular composition of the aerosols before and after reaction is characterized by a soft atmospheric pressure ionization source (Direct Analysis in Real Time)more » coupled with a high-resolution mass spectrometer. The aerosol mass spectra reveal that four major reaction products are formed: a single C 4 functionalization product (C 4H 4O 6) and three C 3 fragmentation products (C 3H 4O 4, C 3H 2O 4, and C 3H 2O 5). The C 4 functionalization product does not appear to originate from peroxy radical self-reactions but instead forms via an α-hydroxylperoxy radical produced by a hydrogen atom abstraction by OH at the tertiary carbon site. The proximity of a hydroxyl group to peroxy group enhances the unimolecular HO 2 elimination from the α-hydroxylperoxy intermediate. This alcohol-to-ketone conversion yields 2-hydroxy-3-oxosuccinic acid (C 4H 4O 6), the major reaction product. While in general, C–C bond scission reactions are expected to dominate the chemistry of organic compounds with high average carbon oxidation states (OS C), our results show that molecular structure can play a larger role in the heterogeneous transformation of tartaric acid (OS C = 1.5). Finally, these results are also compared with two structurally related dicarboxylic acids (succinic acid and 2,3-dimethylsuccinic acid) to elucidate how the identity and location of functional groups (methyl and hydroxyl groups) alter heterogeneous reaction mechanisms.« less

Atmospheric fates of Criegee intermediates in the ozonolysis of isoprene.

PubMed

Nguyen, Tran B; Tyndall, Geoffrey S; Crounse, John D; Teng, Alexander P; Bates, Kelvin H; Schwantes, Rebecca H; Coggon, Matthew M; Zhang, Li; Feiner, Philip; Milller, David O; Skog, Kate M; Rivera-Rios, Jean C; Dorris, Matthew; Olson, Kevin F; Koss, Abigail; Wild, Robert J; Brown, Steven S; Goldstein, Allen H; de Gouw, Joost A; Brune, William H; Keutsch, Frank N; Seinfeld, John H; Wennberg, Paul O

2016-04-21

We use a large laboratory, modeling, and field dataset to investigate the isoprene + O3 reaction, with the goal of better understanding the fates of the C1 and C4 Criegee intermediates in the atmosphere. Although ozonolysis can produce several distinct Criegee intermediates, the C1 stabilized Criegee (CH2OO, 61 ± 9%) is the only one observed to react bimolecularly. We suggest that the C4 Criegees have a low stabilization fraction and propose pathways for their decomposition. Both prompt and non-prompt reactions are important in the production of OH (28% ± 5%) and formaldehyde (81% ± 16%). The yields of unimolecular products (OH, formaldehyde, methacrolein (42 ± 6%) and methyl vinyl ketone (18 ± 6%)) are fairly insensitive to water, i.e., changes in yields in response to water vapor (≤4% absolute) are within the error of the analysis. We propose a comprehensive reaction mechanism that can be incorporated into atmospheric models, which reproduces laboratory data over a wide range of relative humidities. The mechanism proposes that CH2OO + H2O (k(H2O)∼ 1 × 10(-15) cm(3) molec(-1) s(-1)) yields 73% hydroxymethyl hydroperoxide (HMHP), 6% formaldehyde + H2O2, and 21% formic acid + H2O; and CH2OO + (H2O)2 (k(H2O)2∼ 1 × 10(-12) cm(3) molec(-1) s(-1)) yields 40% HMHP, 6% formaldehyde + H2O2, and 54% formic acid + H2O. Competitive rate determinations (kSO2/k(H2O)n=1,2∼ 2.2 (±0.3) × 10(4)) and field observations suggest that water vapor is a sink for greater than 98% of CH2OO in a Southeastern US forest, even during pollution episodes ([SO2] ∼ 10 ppb). The importance of the CH2OO + (H2O)n reaction is demonstrated by high HMHP mixing ratios observed over the forest canopy. We find that CH2OO does not substantially affect the lifetime of SO2 or HCOOH in the Southeast US, e.g., CH2OO + SO2 reaction is a minor contribution (<6%) to sulfate formation. Extrapolating, these results imply that sulfate production by stabilized Criegees is likely unimportant in regions dominated by the reactivity of ozone with isoprene. In contrast, hydroperoxide, organic acid, and formaldehyde formation from isoprene ozonolysis in those areas may be significant.

Enhanced diffusion weighting generated by selective adiabatic pulse trains

NASA Astrophysics Data System (ADS)

Sun, Ziqi; Bartha, Robert

2007-09-01

A theoretical description and experimental validation of the enhanced diffusion weighting generated by selective adiabatic full passage (AFP) pulse trains is provided. Six phantoms (Ph-1-Ph-6) were studied on a 4 T Varian/Siemens whole body MRI system. Phantoms consisted of 2.8 cm diameter plastic tubes containing a mixture of 10 μm ORGASOL polymer beads and 2 mM Gd-DTPA dissolved in 5% agar (Ph-1) or nickel(II) ammonium sulphate hexahydrate doped (56.3-0.8 mM) water solutions (Ph-2-Ph-6). A customized localization by adiabatic selective refocusing (LASER) sequence containing slice selective AFP pulse trains and pulsed diffusion gradients applied in the phase encoding direction was used to measure 1H 2O diffusion. The b-value associated with the LASER sequence was derived using the Bloch-Torrey equation. The apparent diffusion coefficients measured by LASER were comparable to those measured by a conventional pulsed gradient spin-echo (PGSE) sequence for all phantoms. Image signal intensity increased in Ph-1 and decreased in Ph-2-Ph-6 as AFP pulse train length increased while maintaining a constant echo-time. These experimental results suggest that such AFP pulse trains can enhance contrast between regions containing microscopic magnetic susceptibility variations and homogeneous regions in which dynamic dephasing relaxation mechanisms are dominant.

The construction of open Gd(III) metal-organic frameworks based on methanetriacetic acid: new objects with an old ligand.

PubMed

Cañadillas-Delgado, Laura; Martín, Tomás; Fabelo, Oscar; Pasán, Jorge; Delgado, Fernando S; Lloret, Francesc; Julve, Miguel; Ruiz-Pérez, Catalina

2010-04-06

The preparation, X-ray crystallography and magnetic investigation of the first examples of methanetriacetate (mta)-containing lanthanide(III) complexes of formulae [Gd(mta)(H(2)O)(3)](n)4 n H(2)O (1) [Gd(mta)(H(2)O)(3)](n)2 n H(2)O (2) and [Gd(2)(mta)(2)(H(2)O)(2)](n)2 n H(2)O (3) are described herein. This tripodal ligand promotes the formation of 6(3) networks; thus 1 consists of a honeycomb structure, whereas in 2 two of these layers are condensed to form a rare five-connected two-dimensional (4(8)6(2)) network. Compound 3 can be seen as an aggregation of 6(3) layers leading to a three-dimensional (6,6)-connected binodal (4(12)6(3))(4(9)6(6))-nia net, in which the gadolinium(III) ions and the mta ligands act as octahedral and as trigonal prismatic nodes, respectively. The magnetic properties of 1-3 were investigated in the temperature range 1.9-300 K. A close fit to the Curie law (1) and weak either antiferro- [J=-0.0063(1) cm(-1) (2)] or ferromagnetic [J=+0.0264(6) cm(-1) (3)] interactions between the Gd(III) ions are observed; the different exchange pathways involved [extended tris-bidentate mta (1) and mu-O(1);kappa(2)O(1),O(2) (2 and 3) plus single syn-syn carboxylate-mta (3)] accounting for these magnetic features. The nature and magnitude of the magnetic interactions, between the Gd(III) ions in 1-3, agree with the small amount of data existing in the literature for these kind of bridges.

21 CFR 184.1277 - Dextrin.

Code of Federal Regulations, 2014 CFR

2014-04-01

....1277 Dextrin. (a) Dextrin ((C6H10O5)n·H2O, CAS Reg. No. 9004-53-9) is an incompletely hydrolyzed starch..., or sago starches, or by dry heating the starches after: (1) Treatment with safe and suitable alkalis, acids, or pH control agents and (2) drying the acid or alkali treated starch. (b) The ingredient meets...

The reaction of selenium (IV) with ascorbic acid: its relevance in aqueous and soil systems.

PubMed

Pettine, Maurizio; Gennari, Francesca; Campanella, Luigi

2013-01-01

Abiotic processes able to reduce oxidized Se species may have a strong influence on the environmental behavior of selenium since Se toxicity, bioavailability and mobility follow the order Se(-II)0.3), while does not affect significantly the reduction of Se(IV) by H(2)A at low ratios (<0.1). Fe(III) also catalyzes the oxidation of H(2)A but in this case the possible diminution of the reduction rates of Se(IV) by H(2)A are masked by additional processes of adsorption on and coprecipitation by ferric oxyhydroxides, which lower the concentrations of Se(IV). Copyright © 2012 Elsevier Ltd. All rights reserved.

[Phenolic acid derivatives from Bauhinia glauca subsp. pernervosa].

PubMed

Zhao, Qiao-Li; Wu, Zeng-Bao; Zheng, Zhi-Hui; Lu, Xin-Hua; Liang, Hong; Cheng, Wei; Zhang, Qing-Ying; Zhao, Yu-Ying

2011-08-01

To study the chemical constituents of Bauhinia glauca subsp. pernervosa, eleven phenolic acids were isolated from a 95% ethanol extract by using a combination of various chromatographic techniques including column chromatography over silica gel, ODS, MCI, Sephadex LH-20, and semi-preparative HPLC. By spectroscopic techniques including 1H NMR, 13C NMR, 2D NMR, and HR-ESI-MS, these compounds were identified as isopropyl O-beta-(6'-O-galloyl)-glucopyranoside (1), ethyl O-beta-(6'-O-galloyl)-glucopyranoside (2), 3, 4, 5-trimethoxyphenyl-(6'-O-galloyl)-O-beta-D-glucopyranoside (3), 3, 4, 5-trimethoxyphenyl-beta-D-glucopyranoside (4), gallic acid (5), methyl gallate (6), ethyl gallate (7), protocatechuic acid (8), 3, 5-dimethoxy-4-hydroxybenzoic acid (9), erigeside C (10) and glucosyringic acid (11). Among them, compound 1 is a new polyhydroxyl compound; compounds 2, 10, and 11 were isolated from the genus Bauhinia for the first time, and the other compounds were isolated from the plant for the first time. Compounds 6 and 8 showed significant protein tyrosine phosphatase1B (PTP1B) inhibitory activity in vitro with the IC50 values of 72.3 and 54.1 micromol x L(-1), respectively.

Cinnamic acid hydrogen bonds to isoniazid and N'-(propan-2-ylidene)isonicotinohydrazide, an in situ reaction product of isoniazid and acetone.

PubMed

Sarcevica, Inese; Orola, Liana; Veidis, Mikelis V; Belyakov, Sergey

2014-04-01

A new polymorph of the cinnamic acid-isoniazid cocrystal has been prepared by slow evaporation, namely cinnamic acid-pyridine-4-carbohydrazide (1/1), C9H8O2·C6H7N3O. The crystal structure is characterized by a hydrogen-bonded tetrameric arrangement of two molecules of isoniazid and two of cinnamic acid. Possible modification of the hydrogen bonding was investigated by changing the hydrazide group of isoniazid via an in situ reaction with acetone and cocrystallization with cinnamic acid. In the structure of cinnamic acid-N'-(propan-2-ylidene)isonicotinohydrazide (1/1), C9H8O2·C9H11N3O, carboxylic acid-pyridine O-H···N and hydrazide-hydrazide N-H···O hydrogen bonds are formed.

Degradation mechanism of alachlor during direct ozonation and O(3)/H(2)O(2) advanced oxidation process.

PubMed

Qiang, Zhimin; Liu, Chao; Dong, Bingzhi; Zhang, Yalei

2010-01-01

The degradation of alachlor by direct ozonation and advanced oxidation process O(3)/H(2)O(2) was investigated in this study with focus on identification of degradation byproducts. The second-order reaction rate constant between ozone and alachlor was determined to be 2.5+/-0.1M(-1)s(-1) at pH 7.0 and 20 degrees C. Twelve and eight high-molecular-weight byproducts (with the benzene ring intact) from alachlor degradation were identified during direct ozonation and O(3)/H(2)O(2), respectively. The common degradation byproducts included N-(2,6-diethylphenyl)-methyleneamine, 8-ethyl-3,4-dihydro-quinoline, 8-ethyl-quinoline, 1-chloroacetyl-2-hydro-3-ketone-7-acetyl-indole, 2-chloro-2',6'-diacetyl-N-(methoxymethyl)acetanilide, 2-chloro-2'-acetyl-6'-ethyl-N-(methoxymethyl)-acetanilide, and two hydroxylated alachlor isomers. In direct ozonation, four more byproducts were also identified including 1-chloroacetyl-2,3-dihydro-7-ethyl-indole, 2-chloro-2',6'-ethyl-acetanilide, 2-chloro-2',6'-acetyl-acetanilide and 2-chloro-2'-ethyl-6'-acetyl-N-(methoxymethyl)-acetanilide. Degradation of alachlor by O(3) and O(3)/H(2)O(2) also led to the formation of low-molecular-weight byproducts including formic, acetic, propionic, monochloroacetic and oxalic acids as well as chloride ion (only detected in O(3)/H(2)O(2)). Nitrite and nitrate formation was negligible. Alachlor degradation occurred via oxidation of the arylethyl group, N-dealkylation, cyclization and cleavage of benzene ring. After O(3) or O(3)/H(2)O(2) treatment, the toxicity of alachlor solution examined by the Daphnia magna bioassay was slightly reduced. 2009 Elsevier Ltd. All rights reserved.

4-Nitro­aniline–picric acid (2/1)

PubMed Central

Li, Yan-jun

2009-01-01

In the title adduct, C6H3N3O7·0.5C6H6N2O2, the complete 4-nitro­aniline mol­ecule is generated by a crystallographic twofold axis with two C atoms and two N atoms lying on the axis. The mol­ecular components are linked into two dimensional corrugated layers running parallel to the (001) plane by a combination of inter­molecular N—H⋯O and C—H⋯O hydrogen bonds. The phenolic oxygen and two sets of nitro oxygen atoms in the picric acid were found to be disordered with occupancies of 0.81 (2):0.19 (2) and 0.55 (3):0.45 (3) and 0.77 (4):0.23 (4), respectively. PMID:21578004

Benzoxazinoids from Scoparia dulcis (sweet broomweed) with antiproliferative activity against the DU-145 human prostate cancer cell line.

PubMed

Wu, Wan-Hsun; Chen, Tzu-Yu; Lu, Rui-Wen; Chen, Shui-Tein; Chang, Chia-Chuan

2012-11-01

Sweet broomweed (Scoparia dulcis) is an edible perennial medicinal herb widely distributed in tropical and subtropical regions of Asia, Africa, and the Americas. Four compounds, (2R)-7-methoxy-2H-1,4-benzoxazin-3(4H)-one 2-O-β-galactopyranoside [(2R)-HMBOA-2-O-Gal], 3,6-dimethoxy-benzoxazolin-2(3H)-one (3,6-M2BOA), 3-hydroxy-6-methoxy-2-benzoxazolinone (3-OH-MBOA), and scutellarein 7-O-β-glucuronamide, along with eight known compounds, including two 7-methoxy-1,4-benzoxazin-3(2H)-one 3-O-hexopyranosides [(2R)-HMBOA-2-O-Glc and (2R)-HDMBOA-2-O-Glc], 6-methoxy-benzoxazolin-2(3H)-one (MBOA), acteoside, sodium scutellarin, p-coumaric acid, and two monosaccharides (fructose and glucose), were isolated from the aqueous extract of S. dulcis. Antiproliferative activities of the six benzoxazinoid compounds against the DU-145 human prostate cancer cell line were assayed, and one of these displayed an IC₅₀ of 65.8 μg/mL. Copyright © 2012 Elsevier Ltd. All rights reserved.

4-Aza-1-azoniabicyclo­[2.2.2]octa­ne–2-amino­benzoate–2-amino­benzoic acid (1/1/1)

PubMed Central

Arman, Hadi D.; Kaulgud, Trupta; Tiekink, Edward R. T.

2011-01-01

A 4-aza-1-azoniabicyclo­[2.2.2]octane cation, a 2-amino­benzoate anion and a neutral 2-amino­benzoic acid mol­ecule comprise the asymmetric unit of the title compound, C6H13N2 +·C7H6NO2 −·C7H7NO2. An intra­molecular N—H⋯O hydrogen bond occurs in the anion and in the neutral 2-amino­benzoic acid mol­ecule. The cation provides a charge-assisted N—H⋯O hydrogen bond to the anion, and the 2-amino­benzoic acid mol­ecule forms an O—H⋯N hydrogen bond to the unprotonated amino N atom in the cation. In this way, a three-component aggregate is formed. These are connected into a three-dimensional network by amino–carboxyl­ate N—H⋯O hydrogen bonds. N—H⋯N hydrogen bonds are also observed. PMID:22219964

Formation of amino acids and nucleotide bases in a Titan atmosphere simulation experiment.

PubMed

Hörst, S M; Yelle, R V; Buch, A; Carrasco, N; Cernogora, G; Dutuit, O; Quirico, E; Sciamma-O'Brien, E; Smith, M A; Somogyi, A; Szopa, C; Thissen, R; Vuitton, V

2012-09-01

The discovery of large (>100 u) molecules in Titan's upper atmosphere has heightened astrobiological interest in this unique satellite. In particular, complex organic aerosols produced in atmospheres containing C, N, O, and H, like that of Titan, could be a source of prebiotic molecules. In this work, aerosols produced in a Titan atmosphere simulation experiment with enhanced CO (N(2)/CH(4)/CO gas mixtures of 96.2%/2.0%/1.8% and 93.2%/5.0%/1.8%) were found to contain 18 molecules with molecular formulae that correspond to biological amino acids and nucleotide bases. Very high-resolution mass spectrometry of isotopically labeled samples confirmed that C(4)H(5)N(3)O, C(4)H(4)N(2)O(2), C(5)H(6)N(2)O(2), C(5)H(5)N(5), and C(6)H(9)N(3)O(2) are produced by chemistry in the simulation chamber. Gas chromatography-mass spectrometry (GC-MS) analyses of the non-isotopic samples confirmed the presence of cytosine (C(4)H(5)N(3)O), uracil (C(5)H(4)N(2)O(2)), thymine (C(5)H(6)N(2)O(2)), guanine (C(5)H(5)N(5)O), glycine (C(2)H(5)NO(2)), and alanine (C(3)H(7)NO(2)). Adenine (C(5)H(5)N(5)) was detected by GC-MS in isotopically labeled samples. The remaining prebiotic molecules were detected in unlabeled samples only and may have been affected by contamination in the chamber. These results demonstrate that prebiotic molecules can be formed by the high-energy chemistry similar to that which occurs in planetary upper atmospheres and therefore identifies a new source of prebiotic material, potentially increasing the range of planets where life could begin.

Dibenzo-18-crown-6–picric acid–water (1/2/3)

PubMed Central

Saleh, Muhammad Idiris; Kusrini, Eny; Rosli, Mohd Mustaqim; Fun, Hoong-Kun

2008-01-01

In the crown ether ring of the title compound, C20H24O6·2C6H3N3O7·3H2O, the O—C(H2)—C(H2)—O torsion angles indicate a gauche conformation of the ethyl­eneoxy units, while the C—O—C—C torsion angles indicate planarity of these segments; the dihedral angle between the two benzene rings is 44.53 (13)°. In both picric acid mol­ecules, one of the nitro groups is twisted away from the attached ring. The mol­ecules are linked into chains along the b axis via inter­molecular O—H⋯O hydrogen bonds. In addition, the crystal structure is stabilized by C—H⋯O hydrogen bonds and π–π inter­actions [centroid–centroid distance between benzene rings = 3.5697 (16) Å]. PMID:21202944

Magnetically separable Prussian blue analogue Mn₃[Co(CN)₆]₂·nH₂O porous nanocubes as excellent absorbents for heavy metal ions.

PubMed

Hu, Lin; Mei, Ji-Yang; Chen, Qian-Wang; Zhang, Ping; Yan, Nan

2011-10-05

The application of Prussian blue analogue (PBA) Mn(3)[Co(CN)(6)](2)·nH(2)O porous nanocubes as absorbents for heavy metal ions has been demonstrated. The result indicates that Mn(3)[Co(CN)(6)](2)·nH(2)O porous nanocubes with average diameter of 240 nm possess excellent adsorption efficiency for Pb(2+) ions (94.21% at initial Pb(2+) concentration of 10 mg L(-1)). Moreover, Mn(3)[Co(CN)(6)](2)·nH(2)O porous nanocubes can also show high adsorption efficiency on heavy metal ions even in a strong acidic solution due to its chemical stability. Notably, an external magnet could be used to accelerate the separation of Mn(3)[Co(CN)(6)](2)·nH(2)O from the treated solution. It is suggested that the high adsorption efficiency may derive from the large surface area, M(3)(II)[M(III)(CN)(6)](2)·nH(2)O porous framework structure and affinity between polarizable π-electron clouds of the cyanide bridges and heavy metals ions.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thangavelu, Sonia G.; Butcher, Ray J.; Cahill, Christopher L.

Thiophene 2,5-dicarboxylic acid (TDC) was reacted with uranyl acetate dihydrate and one (or none) of six N-donor chelating ligands (2,2'-bipyridine (BPY), 4,4'-dimethyl-2,2'-bipyridine (4-MeBPY), 5,5'-dimethyl-2,2'-bipyridine (5-MeBPY), 6,6'-dimethyl-2,2'-bipyridine (6-MeBPY), 4,4',6,6'-tetramethyl-2,2'-bipyridine (4,6-MeBPY), and tetrakis(2-pyridyl)pyrazine (TPPZ) to result in the crystallization of seven uranyl coordination polymers, which were characterized by their crystal structures and luminescence properties. The seven coordination polymers, Na2[(UO2)2(C6H2O4S)3]·4H2O (1), [(UO2)4(C6H2O4S)5(C10H8N2)2]·C10H10N2·3H2O (2), [(UO2)(C6H2O4S)(C12H12N3)] (3), [(UO2)(C6H2O4S)(C12H12N3)]·H2O (4), [(UO2)2(C6H2O4S)3]·(C12H14N2)·5H2O (5), [(UO2)3(CH3CO2)(C6H2O4S)4](C14H17N2)3·(C14H16N2)·H2O (6), and [(UO2)2(C6H2O4S)3](C24H18N6) (7), consist of either uranyl hexagonal bipyramidal or pentagonal bipyramidal coordination geometries. In all structures, structural variations in the local and global structures of 1–7 are influenced by the positionsmore » (or number) of methyl groups or pyridyl rings on the N-donor species, thus resulting in a wide diversity of structures ranging from single chains, double chains, or 2-D sheets. Direct coordination of N-donor ligands to uranyl centers is observed in the chain structures of 2–4 using BPY, 4-MeBPY, and 5-MeBPY, whereas the N-donor species participate as guests (as either neutral or charge balancing species) in the chain and sheet structures of 5–7 using 6-MeBPY, 4,6-MeBPY, and TPPZ, respectively. Compound 1 is the only structure that does not contain any N-donor ligands and thus crystallizes as a 2-D interpenetrating sheet. The luminescent properties of 1–7 are influenced by the direct coordination or noncoordination of N-donor species to uranyl centers. Compounds 2–4 exhibit typical UO22+ emission upon direct coordination of N-donors, but its absence is observed in 1, 5, 6, and 7, when N-donor species participate as guest molecules. These results suggest that direct coordination of N-donor ligands participate as chromophores, thus resulting in possible UO22+ sensitization. The lack of emission in 1, 5, 6, and 7 may be explained by the extended conjugation of the TDC ligands within their structures.« less

Ab initio studies on Al(+)(H(2)O)(n), HAlOH(+)(H(2)O)(n-1), and the size-dependent H(2) elimination reaction.

PubMed

Siu, Chi-Kit; Liu, Zhi-Feng; Tse, John S

2002-09-11

We report computational studies on Al(+)(H(2)O)(n), and HAlOH(+)(H(2)O)(n-1), n = 6-14, by the density functional theory based ab initio molecular dynamics method, employing a planewave basis set with pseudopotentials, and also by conventional methods with Gaussian basis sets. The mechanism for the intracluster H(2) elimination reaction is explored. First, a new size-dependent insertion reaction for the transformation of Al(+)(H(2)O)(n), into HAlOH(+)(H(2)O)(n-1) is discovered for n > or = 8. This is because of the presence of a fairly stable six-water-ring structure in Al(+)(H(2)O)(n) with 12 members, including the Al(+). This structure promotes acidic dissociation and, for n > or = 8, leads to the insertion reaction. Gaussian based BPW91 and MP2 calculations with 6-31G* and 6-31G** basis sets confirmed the existence of such structures and located the transition structures for the insertion reaction. The calculated transition barrier is 10.0 kcal/mol for n = 9 and 7.1 kcal/mol for n = 8 at the MP2/6-31G** level, with zero-point energy corrections. Second, the experimentally observed size-dependent H(2) elimination reaction is related to the conformation of HAlOH(+)(H(2)O)(n-1), instead of Al(+)(H(2)O)(n). As n increases from 6 to 14, the structure of the HAlOH(+)(H(2)O)(n-1) cluster changes into a caged structure, with the Al-H bond buried inside, and protons produced in acidic dissociation could then travel through the H(2)O network to the vicinity of the Al-H bond and react with the hydride H to produce H(2). The structural transformation is completed at n = 13, coincident approximately with the onset of the H(2) elimination reaction. From constrained ab initio MD simulations, we estimated the free energy barrier for the H(2) elimination reaction to be 0.7 eV (16 kcal/mol) at n = 13, 1.5 eV (35 kcal/mol) at n = 12, and 4.5 eV (100 kcal/mol) at n = 8. The existence of transition structures for the H(2) elimination has also been verified by ab initio calculations at the MP2/6-31G** level. Finally, the switch-off of the H(2) elimination for n > 24 is explored and attributed to the diffusion of protons through enlarged hydrogen bonded H(2)O networks, which reduces the probability of finding a proton near the Al-H bond.

Spectra, energy levels, and energy transition of lanthanide complexes with cinnamic acid and its derivatives.

PubMed

Zhou, Kaining; Feng, Zhongshan; Shen, Jun; Wu, Bing; Luo, Xiaobing; Jiang, Sha; Li, Li; Zhou, Xianju

2016-04-05

High resolution spectra and luminescent lifetimes of 6 europium(III)-cinnamic acid complex {[Eu2L6(DMF)(H2O)]·nDMF·H2O}m (L=cinnamic acid I, 4-methyl-cinnamic acid II, 4-chloro-cinnamic acid III, 4-methoxy-cinnamic acid IV, 4-hydroxy-cinnamic acid V, 4-nitro-cinnamic acid VI; DMF=N, N-dimethylformamide, C3H7NO) were recorded from 8 K to room temperature. The energy levels of Eu(3+) in these 6 complexes are obtained from the spectra analysis. It is found that the energy levels of the central Eu(3+) ions are influenced by the nephelauxetic effect, while the triplet state of ligand is lowered by the p-π conjugation effect of the para-substituted functional groups. The best energy matching between the ligand triplet state and the central ion excited state is found in complex I. While the other complexes show poorer matching because the gap of (5)D0 and triplet state contracts. Copyright © 2016 Elsevier B.V. All rights reserved.

Structural, electronic properties and stability of metatitanic acid (H 2TiO 3) nanotubes

NASA Astrophysics Data System (ADS)

Enyashin, A. N.; Denisova, T. A.; Ivanovskii, A. L.

2009-12-01

Quite recently, metatitanic acid (H 2TiO 3) has been successfully prepared, which extended the family of known titanic acids H 2Ti nO 2n+1 ( n = 2, 3 and 4). Here the atomic models for nanotubes (NTs) of metatitanic acid are designed and their cohesive and electronic properties are considered depending on their chirality and radii by means of density-functional theory-tight-binding (DFTB) method. Our main findings are that the proposed H 2TiO 3 tubes are stable and that all these NTs will be the insulators (independently from their chirality and the diameters) with forbidden gaps at about ˜4.6 eV. We have found also that aforementioned properties of predicted H 2TiO 3 NTs are very similar with those of recently prepared fabricated nanotubes of polytitanic acids; thus, it is possible to expect that the proposed H 2TiO 3 tubular materials may be fabricated.

Potato wound-healing tissues: A rich source of natural antioxidant molecules with potential for food preservation.

PubMed

Dastmalchi, Keyvan; Wang, Isabel; Stark, Ruth E

2016-11-01

The need for safe, effective preservatives is a prominent issue in the food and drug industries, reflecting demand for natural alternatives to synthetic chemicals viewed as harmful to consumers and the environment. Thus, this study determined the identities and scavenging capacities of antioxidant metabolites produced as a response to potato tuber wounding, using activity-guided fractionation of polar extracts from a Yukon Gold cultivar that had previously exhibited exceptionally high radical-scavenging activity. Activity-guided fractionation using the ABTS(+) radical scavenging assay and LC-MS with TOF-MS for compositional analysis of the most potent antioxidant fractions yielded identification of nine constituents: coumaroylputrescine; feruloylquinic acid; isoferuloylputrescine; ferulic acid; 22,25-dimethoxy-3-[[2,3,4-tri-O-methyl-6-O-(2,3,4,6-tetra-O-methyl-β-d-glucopyranosyl)-β-d-glucopyranosyl]oxy]-(3β)-lanost-9(11)-en-24-one; 4-(2Z)-2-decen-1-yl-5-[1-(4-hydroxyphenyl)decyl]-1,2-benzenediol; 8-[(2E)-3,7-dimethyl-2,6-octadien-1-yl]-5-hydroxy-2,8-dimethyl-6-(3-methyl-2-buten-1-yl)-2H-1-benzopyran-4,7(3H,8H)-dione; 3-[(2-O-β-d-glucopyranosyl-β-d-glucopyranosyl)oxy]-20-[(6-O-β-d-xylopyranosyl-β-d-glucopyranosyl)oxy]-dammar-24-en-19-al; (3β)-28-oxo-28-(phenylmethoxy)oleanan-3-yl 2-O-β-d-galactopyranosyl-3-O-(phenylmethyl)-, butyl ester β-d-glucopyranosiduronic acid. A positive correlation was observed between the scavenging activities and the polarities of the active fractions. The antioxidant capacities of the fractions were also characterised by monitoring the activity throughout a 45-minute assay period. Copyright © 2016 Elsevier Ltd. All rights reserved.

Potato Wound-Healing Tissues: A Rich Source of Natural Antioxidant Molecules with Potential for Food Preservation

PubMed Central

Dastmalchi, Keyvan; Wang, Isabel; Stark, Ruth E.

2016-01-01

The need for safe, effective preservatives is a prominent issue in the food and drug industries, reflecting demand for natural alternatives to synthetic chemicals viewed as harmful to consumers and the environment. Thus, this study determined the identities and scavenging capacities of antioxidant metabolites produced as a response to potato tuber wounding, using activity-guided fractionation of polar extracts from a Yukon Gold cultivar that had previously exhibited exceptionally high radical-scavenging activity. Activity-guided fractionation using the ABTS•+ radical scavenging assay and LC-MS with TOF-MS for compositional analysis of the most potent antioxidant fractions yielded identification of nine constituents: coumaroylputrescine; feruloylquinic acid; isoferuloylputrescine; ferulic acid; 22,25-dimethoxy-3-[[2,3,4-tri-O-methyl-6-O-(2,3,4,6-tetra-O-methyl-β-D-glucopyranosyl)-β-D-glucopyranosyl]oxy]-(3β)-lanost-9(11)-en-24-one; 4-(2Z)-2-decen-1-yl-5-[1-(4-hydroxyphenyl)decyl]-1,2-benzenediol; 8-[(2E)-3,7-dimethyl-2,6-octadien-1-yl]-5-hydroxy-2,8-dimethyl-6-(3-methyl-2-buten-1-yl)-2H-1-benzopyran-4,7(3H,8H)-dione; 3-[(2-O-β-D-glucopyranosyl-β-D-glucopyranosyl)oxy]-20-[(6-O-β-D-xylopyranosyl-β-D-glucopyranosyl)oxy]-dammar-24-en-19-al; (3β)-28-oxo-28-(phenylmethoxy)oleanan-3-yl 2-O-β-D-galactopyranosyl-3-O-(phenylmethyl)-, butyl ester β-D-glucopyranosiduronic acid. A positive correlation was observed between the scavenging activities and the polarities of the active fractions. The antioxidant capacities of the fractions were also characterised by monitoring the activity throughout a 45-minute assay period. PMID:27211673

The effect of acidity of electrolyte on the porosity and the nanostructure morphology of electrolytic manganese dioxide

NASA Astrophysics Data System (ADS)

Adelkhani, H.

2012-06-01

The effects of acidity of electrolyte (pH) on the hysteresis behavior, the specific surface area, and nanostructure morphology of electrolytic manganese dioxides (EMDs) have been studied by using the Barrett-Joyner-Halenda (BJH) analysis, X-ray diffraction (XRD) and scanning electron microscopy (SEM) images analysis. EMD samples are electrodeposited at a variable pH (6 to 1) and many fixed pH (2, 3, 4, 5, and 6). Results indicate that pH play key roles in the characteristics of EMD. The samples obtained at low pH (2 and 3) show multi-branched morphology and represent a H4 hysteresis loop. At pH 4 and 5, a uniform and dense structure of MnO2 is obtained without hysteresis behavior. The sample electrodeposited at pH 6 shows a regular reticulate, that its adsorption-desorption isotherm show hysteresis behavior. By electrodeposition at a variable pH, the sample shows a cauliflower-like and multi-branched form. From the viewpoint of classification of isotherm, pH strongly affects on Type of isotherm. The results show that γ-MnO2 is as main-product of electrodeposition and α-MnO2 and β-MnO2 were obtained as side-product at low and high pH, respectively.

H2O2 induced cost effective microwave disintegration of dairy waste activated sludge in acidic environment for efficient biomethane generation.

PubMed

Eswari, A Parvathy; Kavitha, S; Banu, J Rajesh; Karthikeyan, O Parthiba; Yeom, Ick-Tae

2017-11-01

This study aimed to improve the biomethane potential of dairy waste activated sludge (WAS) by H 2 O 2 -acidic pH induced microwave disintegration (HAMW-D) pretreatment approach. The results of HAMW-D compared with the microwave disintegration (MW-D) alone for energy and economic factors. In the two phase disintegration process, the H 2 O 2 concentration of about 0.5mg/g SS under acid pH of 5 was found to be optimum for effective dissociation of Extracellular Polymeric Substances (EPS) matrix. A higher liquefaction of about 46.6% was achieved in HAMW-D when compared to that of MW-D (30%). It subsequently improved the methane yield of about 250mL/g VS in HAMW-D, which was 9.6% higher than MW-D. A net profit of about 49€/ton was achieved for HAMW-D, therefore it is highly recommended for WAS pretreatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

Spectroscopic studies on interaction of BSA and Eu(III) complexes with H5ph-dtpa and H5dtpa ligands.

PubMed

Kong, Deyong; Qin, Cui; Fan, Ping; Li, Bing; Wang, Jun

2015-04-05

An novel aromatic aminopolycarboxylic acid ligand, N-(2-N,N-Dicarboxymethylaminophenyl) ethylenediamine-N,N',N'-triacetic acid (H5ph-dtpa), was synthesized by improving experimental method and its corresponding Eu(III) complex, Na2[EuIII(ph-dtpa)(H2O)]·6H2O, was successfully prepared through heat-refluxing method. As a comparison, the Eu(III) complex with diethylenetriamine-N,N,N',N',N″-pentaacetic acid (H5dtpa) ligand, Na2[Eu(III)(dtpa)(H2O)]·6H2O, was also prepared by the same method. And then, the interaction between prepared Eu(III) complexes ([EuIII(dtpa)(H2O)]2- and [EuIII(ph-dtpa)(H2O)]2-) and bovine serum albumin (BSA) in aqueous solution were studied by the combination of ultraviolet-visible (UV-vis), fluorescence and circular dichroism (CD) spectroscopies. In addition, the binding sites of Eu(III) complexes ([EuIII(dtpa)(H2O)]2- and [EuIII(ph-dtpa)(H2O)]2-) to BSA molecules were also estimated by synchronous fluorescence. Moreover, the theoretical and experimental results show that the Van der Waals, hydrogen bond and π-π stacking interactions are the mainly impulse to the reaction. The binding distances (r) between Eu(III) complexes ([EuIII(dtpa)(H2O)]2- and [EuIII(ph-dtpa)(H2O)]2-) and BSA were obtained according to Förster's non-radiative energy transfer theory. Also, the determined UV-vis absorption spectroscopy, synchronous fluorescence and circular dichroism (CD) spectra showed that the conformation of BSA could be changed in the presence of Eu(III) complexes. The obtained results can help understand the action mode between rare earth metal complexes of aminopolycarboxylic acid ligands with BSA and they are also expected to provide important information of designs of new inspired drugs. Copyright © 2015 Elsevier B.V. All rights reserved.

Spectroscopic studies on interaction of BSA and Eu(III) complexes with H5ph-dtpa and H5dtpa ligands

NASA Astrophysics Data System (ADS)

Kong, Deyong; Qin, Cui; Fan, Ping; Li, Bing; Wang, Jun

2015-04-01

An novel aromatic aminopolycarboxylic acid ligand, N-(2-N,N-Dicarboxymethylaminophenyl) ethylenediamine-N,N‧,N‧-triacetic acid (H5ph-dtpa), was synthesized by improving experimental method and its corresponding Eu(III) complex, Na2[EuIII(ph-dtpa)(H2O)]·6H2O, was successfully prepared through heat-refluxing method. As a comparison, the Eu(III) complex with diethylenetriamine-N,N,N‧,N‧,N″-pentaacetic acid (H5dtpa) ligand, Na2[EuIII(dtpa)(H2O)]·6H2O, was also prepared by the same method. And then, the interaction between prepared Eu(III) complexes ([EuIII(dtpa)(H2O)]2- and [EuIII(ph-dtpa)(H2O)]2-) and bovine serum albumin (BSA) in aqueous solution were studied by the combination of ultraviolet-visible (UV-vis), fluorescence and circular dichroism (CD) spectroscopies. In addition, the binding sites of Eu(III) complexes ([EuIII(dtpa)(H2O)]2- and [EuIII(ph-dtpa)(H2O)]2-) to BSA molecules were also estimated by synchronous fluorescence. Moreover, the theoretical and experimental results show that the Van der Waals, hydrogen bond and π-π stacking interactions are the mainly impulse to the reaction. The binding distances (r) between Eu(III) complexes ([EuIII(dtpa)(H2O)]2- and [EuIII(ph-dtpa)(H2O)]2-) and BSA were obtained according to Förster's non-radiative energy transfer theory. Also, the determined UV-vis absorption spectroscopy, synchronous fluorescence and circular dichroism (CD) spectra showed that the conformation of BSA could be changed in the presence of Eu(III) complexes. The obtained results can help understand the action mode between rare earth metal complexes of aminopolycarboxylic acid ligands with BSA and they are also expected to provide important information of designs of new inspired drugs.

Supramolecular assemblies of tetrafluoroterephthalic acid and N-heterocycles via various strong hydrogen bonds and weak Csbnd H⋯F interactions: Synthons cooperation, robust motifs and structural diversity

NASA Astrophysics Data System (ADS)

Hu, Yanjing; Hu, Hanbin; Li, Yingying; Chen, Ruixin; Yang, Yu; Wang, Lei

2016-10-01

A series of organic solid states including three salts, two co-crystals, and three hydrates based on tetrafluoroterephthalic acid (H2tfBDC) and N-bearing ligands (2,4-(1H,3H)-pyrimidine dione (PID), 2,4-dihydroxy-6-methyl pyrimidine (DHMPI), 2-amino-4,6-dimethyl pyrimidine (ADMPI), 2-amino-4,6-dimenthoxy pyrimidine (ADMOPI), 5,6-dimenthyl benzimidazole (DMBI), 2-aminobenzimidazole (ABI), 3,5-dimethyl pyrazole (DMP), and 3-cyanopyridine (3-CNpy)), namely, [(PID)2·(H2tfBDC)] (1), [(DHMPI)2·(H2tfBDC)] (2), [(H-ADMPI+)2·(tfBDC2-)·2(H2O)] (3), [(H-ADMOPI+)2·(tfBDC2-)·(H2O)] (4), [(H-DMBI+)2·(tfBDC2-)·2(H2O)] (5), [(H-ABI+)2·(tfBDC2-)] (6), [(H-DMP+)·(HtfBDC-)] (7), and [(H-3-CNpy+)·(HtfBDC-)] (8), were synthesized by solvent evaporation method. Crystal structures analyses show that the F atom of the H2tfBDC participates in multiple Csbnd H⋯F hydrogen bond formations, producing different supramolecular synthons. The weak hydrogen bonding Csbnd H⋯F and Nsbnd H⋯F play an important part in constructing the diversity structures 2-8, except in crystal 1. In complexes 1-3, they present the same synthon R22(8) with different N-heterocyclic compounds, which may show the strategy in constructing the supramolecular. Meanwhile, the complex 3 exhibits a 2D layer, and the independent molecules of water exist in the adjacent layers. In complexes 4 and 5, the water molecules connect the neighboring layers to form 3D network by strong Osbnd H⋯O hydrogen bonding. These crystals 1-8 were fully characterized by single-crystal X-ray crystallography, elemental analysis, infrared spectroscopy (IR), and thermogravimetric analysis (TGA).

Synthesis, structure characterization, and anticancer activity of a novel oxygen-bridged tricyclic Biginelli adduct

NASA Astrophysics Data System (ADS)

Ibrahim, Mohamed M.; El-Sheshtawy, Hamdy S.; El-Kemary, Maged; Al-Juaid, Salih; Youssef, Mohamed; El-Azab, Islam H.

2017-06-01

Herein, we report the one-pot cyclization of Biginelli Adduct, ethyl 4-(2-hydroxyphenyl)-6-methyl-2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate (I) to the oxygen-bridged adduct, ethyl 2-methyl-4-thioxo-3,4,5,6-tetrahydro-2H-2,6-methanobenzo[g] [1,3,5]oxadiazocine-11-carboxylate (II) in a high yield and purity under mild reaction condition using zinc(II) perchlorate hexahydrate as a highly efficient catalyst. The cyclic product (II) was characterized both in the solid state and in solution using FT-IR, 1H NMR, and UV-visible spectroscopy. Theoretical calculations using density functional theory with B3LYP/6-311++G(d,p) level were used to further investigate the structure properties. DFT calculations (gas phase) revealed the stability of cyclic compound II (3.45 kcal/mol) than compound I. In addition, the anticancer activity of II was investigated using MCF-7 human breast cell line. The results revealed a moderate activity with 223.55 μg/ml IC50 value.

Aminoalcohols and benzoates-friends or foes? Tuning nuclearity of Cu(ii) complexes, studies of their structures, magnetism, and catecholase-like activities as well as performing DFT and TDDFT studies.

PubMed

Sama, Farasha; Dhara, Ashish Kumar; Akhtar, Muhammad Nadeem; Chen, Yan-Cong; Tong, Ming-Liang; Ansari, Istikhar A; Raizada, Mukul; Ahmad, Musheer; Shahid, M; Siddiqi, Zafar A

2017-08-14

Herein, the coordination chemistry of a series of Cu(ii) complexes of various aminoalcohol and benzoate ligands was explored. The pH-dependent reactions of copper(ii) salts with propanolamine (Hpa), N-methyl diethanolamine (H 2 mdea), triethanolamine (H 3 tea), and n butyl-diethanolamine (H 2 budea) were carried out in the presence of various benzoates (benzoic acid, 2-hydroxy benzoic acid, 4-hydroxy benzoic acid, 3-methoxy benzoic acid, and 4-methoxy benzoic acid). The resulting complexes [Cu 2 (pa) 2 (benzoate) 2 ] (1), [Cu 2 (pa) 2 (3-methoxybenzoate) 2 ] (2), [Cu 2 (pa) 2 (4-methoxybenzoate) 2 ] (3), [Cu 2 (H 2 tea) 2 (benzoate) 2 ]·2H 2 O (4), [Cu 2 (H 2 tea) 2 (2-hydroxybenzoate) 2 ]·2H 2 O (5), [Cu 2 (H 3 tea) 2 (4-hydroxybenzoate) 2 ][Cu(Htea) 2 ]·2H 2 O (6), [Cu(H 2 mdea) 2 ][benzoate] 2 (7), [Cu(H 2 mdea) 2 ][4-methoxybenzoate] 2 (8), [Cu(H 2 bdea) 2 ][2-hydroxybenzoate] 2 (9), [Cu 2 (benzoate) 4 (benzoic acid) 2 ] (10), [Cu 2 (4-methoxybenzoate) 4 (CH 3 CN) 2 ]·4CH 3 CN (11) and [Cu 3 (H 2 tea) 2 (benzoate) 2 (NO 3 ) 2 ] (12) were formed as mono-, di- or trinuclear entities depending upon the pH conditions of the reaction. The complexes were characterized employing spectral, magnetic, single-crystal X-ray and DFT/TDDFT studies. 7 and 8 exhibited emission peaks at 510 and 460 nm, respectively, in the solid-state photoluminescence (PL) spectra. The temperature variable magnetic properties of 1-12 revealed the presence of antiferromagnetic (in 1-3 and 7-11) or ferromagnetic interactions (in 4-6 and 12) with Curie constants C = 0.24 (7), 0.28 (8) or 0.35 cm 3 K mol -1 (9) and Weiss constants θ = -0.34 (7), -0.32 (8) or -0.40 (9) K for the mononuclear complexes. The dinuclear complexes demonstrated J values of -89.2(2) (1), -71.1(3) (2), -59.6(1) (3), 98(1) (4), 79.1(2) (5), -85.4(2) (10) and -89.5(2) (11) cm -1 . Strong ferromagnetic interactions were observed in the case of 6 (J = 172(3) cm -1 and zJ' = 2.3(2) cm -1 ), which were comparable with those of 12 (J 12 = 197(2) cm -1 , J 13 = -9.3(3) cm -1 ). A correlation exists between the Cu-O-Cu angle and magnetic coupling in di- and trinuclear Cu(ii) complexes. Moreover, 4-6 were active catalysts for the oxidation of 3,5-DTBC to 3,5-DTBQ and showed catecholase activity in the order 4 > 5 > 6 (K cat = 943 (4), 698 (5) and 553 h -1 (6)). This order can be rationalized in terms of the electron density on the ligand, which neutralizes the effective positive charge on Cu(ii), thus forming the less or more stable intermediate. The order of catecholase activity and the electronic spectral properties of 4-6 were also investigated by DFT and TDDFT studies, respectively.

Poly[(μ-3,5-dinitro­benzoato)(μ-3,5-dinitro­benzoic acid)rubidium

PubMed Central

Miao, Yanqing; Fan, Tao

2011-01-01

The asymmetric unit of the title compound, [Rb(C7H3N2O6)(C7H4N2O6)]n, comprises an Rb+ cation, a 3,5-dinitro­benzoate anion and a 3,5-dinitro­benzoic acid ligand. The Rb+ cation is nine-coordinated by O atoms from four 3,5-dinitro­benzoate anions and three neutral 3,5-dinitro­benzoic acid ligands. The metal atom is firstly linked by four bridging carboxyl groups, forming a binuclear motif, which is further linked by the nitro groups into a two-dimensional framework along the [110] direction. A short O—H⋯O hydrogen bond between two adjacent carboxy/carboxylate groups occurs. PMID:22090832

A one-step colorimetric acid-base titration sensor using a complementary color changing coordination system.

PubMed

Cho, Hui Hun; Kim, Si Hyun; Heo, Jun Hyuk; Moon, Young Eel; Choi, Young Hun; Lim, Dong Cheol; Han, Kwon-Hoon; Lee, Jung Heon

2016-06-21

We report the development of a colorimetric sensor that allows for the quantitative measurement of the acid content via acid-base titration in a single-step. In order to create the sensor, we used a cobalt coordination system (Co-complex sensor) that changes from greenish blue colored Co(H2O)4(OH)2 to pink colored Co(H2O)6(2+) after neutralization. Greenish blue and pink are two complementary colors with a strong contrast. As a certain amount of acid is introduced to the Co-complex sensor, a portion of greenish blue colored Co(H2O)4(OH)2 changes to pink colored Co(H2O)6(2+), producing a different color. As the ratio of greenish blue and pink in the Co-complex sensor is determined by the amount of neutralization reaction occurring between Co(H2O)4(OH)2 and an acid, the sensor produced a spectrum of green, yellow green, brown, orange, and pink colors depending on the acid content. In contrast, the color change appeared only beyond the end point for normal acid-base titration. When we mixed this Co-complex sensor with different concentrations of citric acid, tartaric acid, and malic acid, three representative organic acids in fruits, we observed distinct color changes for each sample. This color change could also be observed in real fruit juice. When we treated the Co-complex sensor with real tangerine juice, it generated diverse colors depending on the concentration of citric acid in each sample. These results provide a new angle on simple but quantitative measurements of analytes for on-site usage in various applications, such as in food, farms, and the drug industry.

Eight supramolecular assemblies constructed from bis(benzimidazole) and organic acids through strong classical hydrogen bonding and weak noncovalent interactions

NASA Astrophysics Data System (ADS)

Jin, Shouwen; Wang, Daqi

2014-05-01

Eight crystalline organic acid-base adducts derived from alkane bridged bis(N-benzimidazole) and organic acids (2,4,6-trinitrophenol, p-nitrobenzoic acid, m-nitrobenzoic acid, 3,5-dinitrobenzoic acid, 5-sulfosalicylic acid and oxalic acid) were prepared and characterized by X-ray diffraction analysis, IR, mp, and elemental analysis. Of the eight compounds five are organic salts (1, 4, 6, 7 and 8) and the other three (2, 3, and 5) are cocrystals. In all of the adducts except 1 and 8, the ratio of the acid and the base is 2:1. All eight supramolecular assemblies involve extensive intermolecular classical hydrogen bonds as well as other noncovalent interactions. The role of weak and strong noncovalent interactions in the crystal packing is ascertained. These weak interactions combined, all the complexes displayed 3D framework structure. The results presented herein indicate that the strength and directionality of the classical N+-H⋯O-, O-H⋯O, and O-H⋯N hydrogen bonds (ionic or neutral) and other nonbonding associations between acids and ditopic benzimidazoles are sufficient to bring about the formation of cocrystals or organic salts.

Synthesis of BaW2O7-ethylene glycol inorganic-organic hybrid and its topochemical transformation to thin WS2 nanoplates

NASA Astrophysics Data System (ADS)

Afanasiev, Pavel

2018-02-01

A novel inorganic-organic hybrid barium tungstate - ethylene glycol Ba(C2H6O2)W2O7 phase has been prepared by non-aqueous precipitation and characterized. According to powder X-ray diffraction, the solid has an orthorhombic lattice (a = b = 6.415 Å, c = 13.05 Å) and represents a derivative of the H2W2O7 lamellar acid. The Ba(C2H6O2)W2O7 hybrid material is a layered solid and crystallizes as thin plates, which can be further topotacticaly transformed to few-layer WS2 nanoplates. Tungsten sulfide as obtained possesses high specific surface area and increased defectness of layers. Thin-layer WS2 materials as prepared show advantageous properties as hydrogen evolution electrocatalysts, or in combination with TiO2 as co-catalysts for photo catalytic hydrogen production from methanol.

Lebbeckoside C, a new triterpenoid saponin from the stem barks of Albizia lebbeck inhibits the growth of human glioblastoma cells.

PubMed

Noté, Olivier Placide; Ngo Mbing, Joséphine; Kilhoffer, Marie-Claude; Pegnyemb, Dieudonné Emmanuel; Lobstein, Annelise

2018-02-19

One new acacic acid-type saponin, named lebbeckoside C (1), was isolated from the stem barks of Albizia lebbeck. Its structure was established on the basis of extensive analysis of 1D and 2D NMR ( 1 H, 13 C NMR, DEPT, COSY, TOCSY, ROESY, HSQC and HMBC) experiments, HRESIMS studies, and by chemical evidence as 3-O-[β-d-xylopyranosyl-(l→2)-β-d-fucopyranosyl-(1→6)-[β-d-glucopyranosyl(1→2)]-β-d-glucopyranosyl]-21-O-{(2E,6S)-6-O-{4-O-[(2E,6S)-2,6-dimethyl-6-O-(β-d-quinovopyranosyl)octa-2,7-dienoyl]-4-O-[(2E,6S)-2,6-dimethyl-6-O-(β-d-quinovopyranosyl)octa-2,7-dienoyl]-β-d-quinovopyranosyl}-2,6-dimethylocta-2,7-dienoyl}acacic acid 28 O-[β-d-quinovopyranosyl-(l→3)-[α-l-arabinofuranosyl-(l→4)]-α-l-rhamnopyranosyl-(l→2)-β-d-glucopyranosyl] ester. The isolated saponin (1) displayed significant cytotoxic activity against the human glioblastoma cell line U-87 MG and TG1 stem-like glioma cells isolated from a patient tumor with IC 50 values of 1.69 and 1.44 μM, respectively.

Coligand-regulated assembly, fluorescence, and magnetic properties of Co(II) and Cd(II) complexes with a non-coplanar dicarboxylate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xin, Ling-Yun; Liu, Guang-Zhen, E-mail: gzliuly@126.com; Ma, Lu-Fang

A non-coplanar dicarboxylate ndca (H{sub 2}ndca=5-norbornene-2,3-dicarboxylic acid), combining with various dipyridyl-typed tectons, constructs six Cd(II)/Co(II) coordination polymers under hydrothermal conditions, namely [Co(ndca)(H{sub 2}O)]{sub n} (1), ([Co(ndca)(bpe)(H{sub 2}O)]·H{sub 2}O){sub n} (2), [Co(ndca)(bpa){sub 0.5}(H{sub 2}O)]{sub n} (3), [Cd(ndca)(bpe)(H{sub 2}O)]{sub n} (4), ([Cd(ndca)(bpa)(H{sub 2}O)]·0.5H{sub 2}O){sub n} (5), and ([Cd(ndca)(bpp) (H{sub 2}O)]·H{sub 2}O){sub n} (6) (bpe=1,2-di(4-pyridyl)ethylene, bpa=1,2-bi(4-pyridyl)ethane, and bpp=1,3-bis(4-pyridyl)propane). All these compounds contain various metal(II)–carboxylate motifs, including carboxylate binuclear (2, 4, 5), carboxylate chain (1, 6) and carboxylate layer (3), which are further extended by dipyridyl-typed coligands to afford a vast diversity of the structures with 2D pyknotic layers (1, 6), 2D open layermore » (5), 2D→3D interpenetrated networks (2,4), and 3D pillared-layer framework (3), respectively. In addition, fluorescent spectra of Cd(II) complexes and magnetic properties of Co(II) complexes are also given. - Graphical abstract: Six various cadmium(II)/cobalt(II)–organic frameworks were constructed by 5-norbornene-2,3-dicarboxylic acid and different bis(pyridine) rod-like tectons, and Cd (II) complexes exhibit blue–violet emissions, whereas Co (II) complexes show antiferromagnetic behaviours. Display Omitted.« less

Plant-derived juvenile hormone III analogues and other sesquiterpenes from the stem bark of Cananga latifolia.

PubMed

Yang, Heejung; Kim, Hye Seong; Jeong, Eun Ju; Khiev, Piseth; Chin, Young-Won; Sung, Sang Hyun

2013-10-01

Juvenile hormone III (JH III) is a larval metamorphosis-regulating hormone present in most insect species. JH III was first isolated from the plant, Cyperus iria L., but the presence of JH III has not been reported in other plant species. In the present study, proof of the existence of JH III and its analogues from Cananga latifolia was established. From an aqueous MeOH extract of C. latifolia stem bark, six compounds were isolated along with nine known compounds. These were identified by using spectroscopic analyses as: (2E,6E,10R)-11-butoxy-10-hydroxy-3,7,11-trimethyldodeca-2,6-dienoic acid methyl ester, (2E,6E)-3,7,11-trimethyl-10-oxododeca-2,6-dienoic acid methyl ester, (2E)-3-methyl-5-[(1S,2R,6R)-1,2,6-trimethyl-3-oxocyclohexyl]-pent-2-enoic acid methyl ester, 1β-hydroxy-3-oxo-4β, 5α,7α-H-eudesmane 11-O-α-l-rhamnopyranoside, 4-epi-aubergenone 11-O-2',3'-di-O-acetyl-α-l-rhamnopyranoside and 4-epi-aubergenone 11-O-2',4'-di-O-acetyl-α-l-rhamnopyranoside. Three of the previously known compounds, (2E,6E,10R)-10-hydroxy-3,7,11-trimethyldodeca-2,6,11-trienoaic acid methyl ester, (2E,6E,10R)-10,11-dihydroxy-3,7,11-trimethyldodeca-2,6-dienoic acid and (2E,6S)-3-methyl-6-hydroxy-6-[(2R,5R)-5-(2-hydroxypropan-2-yl)-2-methyltetrahydrofuran-2-yl]-hex-2-enoaic acid methyl ester have now been found in a plant species. Ultra performance liquid chromatography-quadruple time-of-flight mass spectroscopy (UPLC-QTOF/MS) analysis of the chemical constituents of C. latifolia showed that several were predominant in the sub-fractions of a C. latifolia stem bark extract. Copyright © 2013 Elsevier Ltd. All rights reserved.

Two new lignan glycosides from the seeds of Cuscuta chinensis.

PubMed

He, Xiang-Hui; Yang, Wen-Zhi; Meng, A-Hui; He, Wen-Ni; Guo, De-An; Ye, Min

2010-11-01

Two new lignan glycosides, 2'-hydroxyl asarinin 2'-O-β-D-glucopyranoside (cuscutoside C, 1) and 2'-hydroxyl asarinin 2'-O-β-D-apiofuranosyl-(1 → 2)-[β-D-glucopyranosyl-(1 → 6)]-β-D-glucopyranoside (cuscutoside D, 2), were isolated from the seeds of Cuscuta chinensis Lam., along with six known compounds, 2'-hydroxyl asarinin 2'-O-β-D-glucopyranosyl-(1 → 6)-β-D-glucopyranoside (3), 2'-hydroxyl asarinin 2'-O-β-D-apiofuranosyl-(1 → 2)-β-D-glucopyranoside (cuscutoside A, 4), kaempferol 3,7-di-O-β-D-glucopyranoside (5), 5-caffeoyl quinic acid (6), 4-caffeoyl quinic acid (7), and cinnamic acid (8). Their structures were elucidated on the basis of spectroscopic analyses including HR-ESI-MS, ESI-MS/MS, (1)H and (13)C NMR, HSQC, HMBC, and TOCSY.

Experimental studies on equilibrium adsorption isosteres and determination of the thermodynamic quantities of polar media on alumina Al2O3

NASA Astrophysics Data System (ADS)

Yonova, Albena

2017-03-01

The present work is a revieif of theoretical and experimental study on the adsorption performance of the adsorbent Alumina (Al2O3) used in the adsorption system. An experimental investigation on the equilibrium adsorption isosteres at low pressure (< 1 atm) of working pairs Al2O3/H2O and Al2O3/C2H6O2 is carried out. The isovolume measurement method is adopted in the test setup to directly measure the saturated vapor pressures of working pairs at vapor-liquid equilibrium (dG=0 and dμi=0). Quantity adsorbed is determined from pressure, volume and temperature using gas law. The isosteric heat of adsorption is calculated from the slope of the plot of lnP versus 1/T different amounts of adsorbate onto adsorbent as follows: 0,01 vol% Al2O3/H2O; 0,03 vol% Al2O3/H2O; 0,1 vol% Al2O3/H2O; 0,01 vol% Al2O3/C2H6O2; 0,03 vol% Al2O3/C2H6O2; 0,1 vol% Al2O3/C2H6O2. This study shows that adsorption working pair Al2O3 C2H6O2 has better adsorption performances than those of the A2O3/H2O. Surface acidity! is a most important property! far both adsorption and catalysis and therefore is examined structure of active sites of alumina surface. Thermodynamic parameters such as isosteric heat of adsorption, isosteric enthalpy and entropy of adsorption are critical design variables in estimating the performance and predicting the mechanism of an adsorption process and are also one of the basic requirements for the characterization and optimization of an adsorption process

[Enhanced electro-chemical oxidation of Acid Red 3R solution with phosphotungstic acid supported on gamma-Al2O3].

PubMed

Yue, Lin; Wang, Kai-Hong; Guo, Jian-Bo; Yang, Jing-Liang; Liu, Bao-You; Lian, Jing; Wang, Tao

2013-03-01

Supported phosphotungstic acid catalysts on gamma-Al2O3 (HPW/gamma-Al2O3) were prepared by solution impregnation and characterized by FTIR, XRD, TG-DTA and SEM. The heteropolyanion shows a Keggin structure. Electro-chemical oxidation of Acid Red 3R was investigated in the presence of HPW supported on gamma-Al2O3 as packing materials in the reactor. The results show that HPW/gamma-Al2O3 has a good catalytic activity for decolorization of Acid Red 3R. When HPW loading was 4.6%, pH value of Acid Red 3R was 3, the voltage was 25.0 V, air-flow was 0.04 m3 x h(-1), and electrode span was 3.0 cm, the decolorization efficiency of Acid Red 3R can reach 97.6%. The removal rate of color had still about 80% in this electro-chemical oxidation system, after HPW/gamma-Al2O3 was used for 10 times, but active component loss existed. The interim product was analyzed by means of Vis-UV absorption spectrum. It shows that the conjugated structure of dye is destroyed primarily.

Single Electron Delivery to Lewis Pairs: An Avenue to Anions by Small Molecule Activation.

PubMed

Liu, Liu Leo; Cao, Levy L; Shao, Yue; Stephan, Douglas W

2017-07-26

Single electron transfer (SET) reactions are effected by the combination of a Lewis acid (e.g., E(C 6 F 5 ) 3 E = B or Al) with a small molecule substrate and decamethylferrocene (Cp* 2 Fe). Initially, the corresponding reactions of (PhS) 2 and (PhTe) 2 were shown to give the species [Cp* 2 Fe][PhSB(C 6 F 5 ) 3 ] 1 and [Cp* 2 Fe][(μ-PhS)(Al(C 6 F 5 ) 3 ) 2 ] 2 and [Cp* 2 Fe][(μ-PhTe)(Al(C 6 F 5 ) 3 ) 2 ] 3, respectively. Analogous reactions with di-tert-butyl peroxide yielded [Cp* 2 Fe][(μ-HO)(B(C 6 F 5 ) 3 ) 2 ] 4 with isobutene while with benzoyl peroxide afforded [Cp* 2 Fe][PhC(O)OE(C 6 F 5 ) 3 ] (E = B 5, Al 6). Evidence for a radical pathway was provided by the reaction of Ph 3 SnH and p-quinone afforded [Cp* 2 Fe][HB(C 6 F 5 ) 3 ] 7 and [Cp* 2 Fe] 2 [(μ-O 2 C 6 H 4 )(E(C 6 F 5 ) 3 ) 2 ] (E = B 8, Al 9). In addition, the reaction of TEMPO with Lewis acid and Cp* 2 Fe afforded [Cp* 2 Fe][(C 5 H 6 Me 4 NOE(C 6 F 5 ) 3 ] (E = B 10, Al 11). Finally, reactions with O 2 , Se, Te and S 8 gave [Cp* 2 Fe] 2 [((C 6 F 5 ) 2 Al(μ-O)Al(C 6 F 5 ) 3 ) 2 ] 2 12, [Cp* 2 Fe] 2 [((C 6 F 5 ) 2 Al(μ-Se)Al(C 6 F 5 ) 3 ) 2 ] 2 13, [Cp* 2 Fe][(μ-Te) 2 (Al(C 6 F 5 ) 2 ) 3 ] 14 and [Cp* 2 Fe] 2 [(μ-S 7 )B(C 6 F 5 ) 3 ) 2 ] 15, respectively. The mechanisms of these SET reactions are discussed, and the ramifications are considered.

Characterization of two minor saponins from Cordia piauhiensis by 1H and 13C NMR spectroscopy.

PubMed

Santos, Renata P; Silveira, Edilberto R; Lemos, Telma Leda G; Viana, Francisco Arnaldo; Braz-Filho, Raimundo; Pessoa, Otília Deusdênia L

2005-06-01

A careful NMR analysis with full assignment of the 1H and 13C spectral data for two minor saponins isolated from stems of Cordia piauhiensis is reported. These saponins were isolated by high-performance liquid chromatography and characterized as 3beta-O-[alpha-L-rhamnopyranosyl-(1 --> 2)-beta-D-glucopyranosyl]pomolic acid 28-O-[beta-D-glucopyranosyl-(1 --> 6)-beta-D-glucopyranosyl] ester (1) and 3beta-O-[alpha-L-rhamnopyranosyl-(1 --> 2)-beta-D-glucopyranosyl]oleanolic acid 28-O-[beta-D-xylopyranosyl-(1 --> 2)-beta-D-glucopyranosyl-(1 --> 6)-beta-D-glucopyranosyl] ester (2). Their structures were established using a combination of 1D and 2D (1H, 1H-COSY, TOCSY, NOESY, gs-HMQC and gs-HMBC) NMR techniques, electrospray ionization mass spectrometry and chemical evidence. Copyright 2005 John Wiley & Sons, Ltd.

Facile solvothermal synthesis of mesostructured Fe3O4/chitosan nanoparticles as delivery vehicles for pH-responsive drug delivery and magnetic resonance imaging contrast agents.

PubMed

Zhao, Guanghui; Wang, Jianzhi; Peng, Xiaomen; Li, Yanfeng; Yuan, Xuemei; Ma, Yingxia

2014-02-01

We report a facile fabrication of a host-metal-guest coordination-bonding system in a mesostructured Fe3O4/chitosan nanoparticle that can act as a pH-responsive drug-delivery system. The mesostructured Fe3O4/chitosan was synthesized by a solvothermal approach with iron(III) chloride hexahydrate as a precursor, ethylene glycol as a reducing agent, ammonium acetate as a porogen, and chitosan as a surface-modification agent. Subsequently, doxorubicin (DOX), acting as a model drug (guest), was loaded onto the mesostructured Fe3O4/chitosan nanoparticles, with chitosan acting as a host molecule to form the NH2-Zn(II)-DOX coordination architecture. The release of DOX can be achieved through the cleavage of coordination bonds that are sensitive to variations in external pH under weakly acidic conditions. The pH-responsive nature of the nanoparticles was confirmed by in vitro releases and cell assay tests. Furthermore, the relaxation efficiency of the nanoparticles as high-performance magnetic resonance imaging contrast agents was also investigated. Experimental results confirm that the synthesized mesostructured Fe3O4/chitosan is a smart nanovehicle for drug delivery owing to both its pH-responsive nature and relaxation efficiency. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An effective iodide formulation for killing Bacillus and Geobacillus spores over a wide temperature range.

PubMed

Kida, N; Mochizuki, Y; Taguchi, F

2004-01-01

To develop a sporicidal reagent which shows potent activity against bacterial spores not only at ambient temperatures but also at low temperatures. Suspension tests on spores of Bacillus and Geobacillus were conducted with the reagent based on a previously reported agent (N. Kida, Y. Mochizuki and F. Taguchi, Microbiology and Immunology 2003; 47: 279-283). The modified reagent (tentatively designated as the KMT reagent) was composed of 50 mmol l(-1) EDTA-2Na, 50 mmol l(-1) ferric chloride hexahydrate (FeCl(3).6H(2)O), 50 mmol l(-1) potassium iodide (KI) and 50% ethanol in 0.85% NaCl solution at pH 0.3. The KMT reagent showed significant sporicidal activity against three species of Bacillus and Geobacillus spores over a wide range of temperature. The KMT reagent had many practical advantages, i.e. activity was much less affected by organic substances than was sodium hypochlorite, it did not generate any harmful gas and it was stable for a long period at ambient temperatures. The mechanism(s) of sporicidal activity of the KMT reagent was considered to be based on active iodine species penetrating the spores with enhanced permeability of the spore cortex by a synergistic effect of acid, ethanol and generated active oxygen. The data suggest that the KMT reagent shows potent sporicidal activity over a wide range temperatures and possesses many advantages for practical applications. The results indicate development of a highly applicable sporicidal reagent against Bacillus and Geobacillus spores.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xiao, Zhenyu; Yang, Xiao; Zhao, Siwei

Eight new metal–organic hybrid materials, namely {Cd(Tcph)(4,4′-bipy)_1_/_2} (1), {[Cd_2(Tcph)_2(1,4-bimb)_1_/_2(H_2O)_4]·H_2O} (2), {Cd_2(Tcph)_2(1,4-bmimb)_1_/_2(H_2O)_4} (3), {Cd(Tcph)(1,2-bmimb)} (4), {Cu(Tcph)(1,4-bimb)(H_2O)} (5), {[Co(Tcph)(1,4-bimb)_1_/_2(H_2O)_3]·(H_2O)} (6), {Zn(Tcph)(1,2-bimb)} (7), {Cu_2(Tcph)_2(1,2-bimb)(H_2O)_4} (8), where Tcph=tetrachlorophthalate acid, 4,4′-bipy=4,4′-bipyridine, 1,4-bimb=1,4-bis(imidazol-1-ylmethyl)benzene, 1,4-bmimb=1,4-bis(2-methylimidazol-1-ylmethyl)benzene, 1,2-bimb=1,2-bis(imidazol-1-ylmethyl)-benzene, 1,2-bmimb=1,2-bis(2-methylimidazol-1-ylmethyl)benzene, have been synthesized and characterized. Their structures are determined by single crystal X-ray diffraction and further characterized by infrared spectra (IR) and thermogravimetric (TG) analyses. Complex 1, 4 and 7 display 2D layer structures. 1 possesses two-dimensional sheet containing an unusual [Cd(Tcph)] chains linked by 4,4′-bipy co-ligand, while 4 and 7 hold the similar 4-connected 4{sup 4}-sql nets. Complex 2 and 3 feature a similar three dimensional (3D) internal compensationmore » structure with a topology of {4"2·6"3·8}{sub 2}{6"3}. 5 is a novel 2-fold self-penetrating 3D network with 4-coordinated 6{sup 5}·8–CdSO{sub 4} subnets. The ladder-like chains of 6 are further connected through O–H···O interactions to yield a 3D supramolecular structure. 8 is a discrete tetranuclear complex. The thermal stabilities of 1–8 and the luminescent properties of 1–4 and 7 in the solid state are also discussed. - Graphical abstract: Structure diversity and photoluminescence of eight new metal–organic hybrid materials constructed by Tetrachlorophthalate acid and different N-donor coligands are discussed in the context. - Highlights: • Eight new coordination polymers were synthesized based on mix-ligand strategy. • Complex 2 and 3 feature a similar 3D structure with {4"2·6"3·8}{sub 2}{6"3} topology. • Seven coordination modes of tetrachlorophthalic anions have been found.« less

Synthesis, crystal structures and luminescent properties of zinc(II) metal–organic frameworks constructed from terpyridyl derivative ligand

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Xiao-Le; Shangguan, Yi-Qing; Hu, Huai-Ming, E-mail: ChemHu1@NWU.EDU.CN

2014-08-15

Five zinc(II) metal–organic frameworks, [Zn{sub 3}(344-pytpy){sub 2}Cl{sub 6}]{sub n}·n(H{sub 2}O) (1), [Zn(344-pytpy)(ox)]{sub n} (2), [Zn{sub 2}(344-pytpy)(bdc){sub 2}]{sub n}·1.5n(H{sub 2}O) (3), [Zn{sub 2}(344-pytpy){sub 2} (sfdb){sub 2}]{sub n}·1.5n(H{sub 2}O) (4) and [Zn{sub 3}(344-pytpy){sub 2}(btc){sub 2}]{sub n}·2n(H{sub 2}O) (5), (344-pytpy=4′-(3-pyridyl)-4,2′:6′,4″-terpyridine, H{sub 2}ox=oxalic acid, H{sub 2}bdc=1,4-benzenedi-carboxylic acid, H{sub 2}sfdb=4,4′-sulfonyldibenzoic acid and H{sub 3}btc=1,3,5-benzene-tricarboxylic acid) have been prepared by hydrothermal reactions. Compound 1 is a 1D chain structure, in which 344-pytpy ligand links three Zn{sup II} centers through three of terminal N-donors. Compound 2 is a 4-connected 3D framework with the dia topological net and the Schläfli symbol of 6{sup 6}. Compound 3 displays amore » unusual 3-fold interpenetrating 3D coordination network which exhibits a new intriguing (3,3,4)-connected topological net with the Schläfli symbol of (4.8{sup 2})(4.8{sup 5})(8{sup 3}). Compound 4 features a two-fold interpenetrating 4-connected 2D framework with the sql topological net and the Schläfli symbol of (4{sup 4}.6{sup 2}). Compound 5 is a new self-interpenetrating (3,3,4,4)-connected topological net with the Schläfli symbol of (6.8{sup 2}){sub 2}(6{sup 2}.8{sup 2}.10.12)(6{sup 2}.8{sup 3}.10){sub 2}(6{sup 2}.8){sub 2}. The luminescence properties of 1–5 have been investigated by emission spectra and they possess great thermal stabilities which can be stable up to around 400 °C. - Graphical abstract: Five new Zn(II) metal–organic frameworks based on dicarboxylate and terpyridyl derivative ligands have been synthesized by hydrothermal reactions, giving networks from 1D to 3D structures. The thermal stability and luminescent property have been investigated. - Highlights: • Five zinc(II) metal–organic frameworks have been prepared under hydrothermal conditions. • Their crystal and topological structures have been investigated. • The luminescent properties have been investigated. • They possess great thermal stabilities which can be stable up to around 400 °C.« less

Influence of collector surface composition and water chemistry on the deposition of cerium dioxide nanoparticles: QCM-D and column experiment approaches.

PubMed

Liu, Xuyang; Chen, Gexin; Su, Chunming

2012-06-19

The deposition behavior of cerium dioxide (CeO(2)) nanoparticles (NPs) in dilute NaCl solutions was investigated as a function of collector surface composition, pH, ionic strength, and organic matter (OM). Sensors coated separately with silica, iron oxide, and alumina were applied in quartz crystal microbalance with dissipation (QCM-D) to examine the effect of these mineral phases on CeO(2) deposition in NaCl solution (1-200 mM). Frequency and dissipation shift followed the order: silica > iron oxide > alumina in 10 mM NaCl at pH 4.0. No significant deposition was observed at pH 6.0 and 8.5 on any of the tested sensors. However, ≥ 94.3% of CeO(2) NPs deposited onto Ottawa sand in columns in 10 mM NaCl at pH 6.0 and 8.5. The inconsistency in the different experimental approaches can be mainly attributed to NP aggregation, surface heterogeneity of Ottawa sand, and flow geometry. In QCM-D experiments, the deposition kinetics was found to be qualitatively consistent with the predictions based on the classical colloidal stability theory. The presence of low levels (1-6 mg/L) of Suwannee River humic acid, fulvic acid, alginate, citric acid, and carboxymethyl cellulose greatly enhanced the stability and mobility of CeO(2) NPs in 1 mM NaCl at pH 6.5. The poor correlation between the transport behavior and electrophoretic mobility of CeO(2) NPs implies that the electrosteric effect of OM was involved.

Synthesis of "trans"-4,5-Bis-dibenzylaminocyclopent-2-Enone from Furfural Catalyzed by ErCl[subscript 3]·6H[subscript 2]O

ERIC Educational Resources Information Center

Estevão, Mónica S.; Martins, Ricardo J. V.; Alfonso, Carlos A. M.

2017-01-01

An experiment exploring the chemistry of the carbonyl group for the one-step synthesis of "trans"-4,5- dibenzylaminocyclopent-2-enone is described. The reaction of furfural and dibenzylamine in the environmentally friendly solvent ethanol and catalyzed by the Lewis acid ErCl[subscript 3]·6H[subscript 2]O afforded the product in high…

Effects of acidic rain and ozone on nitrogen fixation and photosynthesis in the lichen lobaria pulmonaria (L. ) Hoffm

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sigal, L.L.; Johnston, J.W.

1986-01-01

The lichen Lobaria pulmonaria was subjected to ozone fumigations at 118, 235 and 353 mcg/cu m and simulated acidic rain at pH levels of 2.6, 4.2 and 5.6 for 5 days (M,W,F,M,W) during a 10-day period. Acidic rain at pH 2.6 caused significant reduction in nitrogen fixation and gross photosynthesis of 100 and 90%, respectively, and thallus bleaching was apparent. There were no significant differences between the pH 5.6 and 4.2 treatments in either gross photosynthesis or nitrogen fixation, and the color of the lichen thalli was unchanged. The effect of ozone on nitrogen fixation and photosynthesis over the rangemore » of concentrations used was not significant, but there was a trend toward reduced nitrogen fixation with increasing O/sub 3/ concentration. There were no significant ozone-acidic rain interactions. The threshold for response to rain acidity for L. pulmonaria lies between pH 2.6 and 4.2, and the acidity of wet deposition in parts of the United States may fall in the range.« less

One new galloyl glycoside from fresh leaves of Psidium guajava L.

PubMed

Shu, Ji-cheng; Chou, Gui-xin; Wang, Zheng-tao

2010-03-01

To investigate the chemical constituents of Psidium Guajava L, the EtOH/H2O extract of the fresh leaves was subjected to various chromatography. Five constituents with galloyl moiety were isolated and elucidated as 1-O-(1, 2-propanediol)-6-O-galloyl-beta-D-glucopyranoside (1), gallic acid (2), ellagic acid (3), ellagic acid-4-O-beta-D-glucopyranoside (4) and quercetin-3-O-(6"-galloyl) beta-D-galactopyranoside (5) by spectroscopic methods, including 2D NMR and HR-ESI-MS spectrometry as well as by comparison with published data. Compounds 4 and 5 were obtained from P. guajava for the first time, and compound 1 is a new polyhydroxyl compound.

Oxidation of 2,6-di-tert-butyl-4-methylphenol. The structure of C14H22O3

USGS Publications Warehouse

Yohe, G.R.; Dunbar, J.E.; Lansford, M.W.; Pedrotti, R.L.; Scheidt, F.M.; Lee, F.G.H.; Smith, E.C.

1959-01-01

The acidic compound C14H22O3, previously reported without assignment of structure as an oxidation product of 2,6-di-tert-butyl-4-methylphenol, is now believed to be DL-trans-5,6-di-tert-butyl-2-hydroxy-1,4-diketo-2-cyclohexene (I). Chemical properties are described and infrared spectra are presented in support of this structure. This structure is of interest in relation to the problem of the existence of o-di-tert-alkylbenzene derivatives. The relatively easy racemization of optically active I suggests that its completely enolized form, 5,6-di-tert-butyl-1,2,4-trihydroxybenzene, is capable of transitory existence.

Synthesis, crystallographic and spectral studies of homochiral cobalt(II) and nickel(II) complexes of a new terpyridylaminoacid ligand

NASA Astrophysics Data System (ADS)

Wang, Xing; Gao, Chang-Qing; Gao, Zhi-Yang; Wu, Ben-Lai; Niu, Yun-Yin

2018-04-01

Based on a chiral terpyridylaminoacid ligand, a series of homochiral Co(II) and Ni(II) complexes, namely, [Co(H2L)(HL)]·Cl·(PF6)2·2H2O (1), [Ni(H2L)(HL)]·Cl·(PF6)2 (2), [Co2(L)2(CH3OH)(H2O)]·(PF6)2·CH3OH (3), [Ni2(L)2(CH3OH)2]·(PF6)2·2CH3OH (4), [Co2(L)2(N3)2]·3H2O (5), and [Ni2(L)2(SCN)2]·4H2O (6) have been successfully synthesized and characterized by elemental analysis, TGA, spectroscopic methods (IR, CD and electronic absorption spectra) and single-crystal X-ray diffraction structural analysis (HL = (S)-2-((4-([2,2':6‧,2″-terpyridin]-4‧-yl)benzyl)amino)-4-methylpentanoic acid). In the acidic reaction conditions, one protonated (H2L)+ and one zwitterionic HL only used their terpyridyl groups to chelate one metal ion Co(II) or Ni(II), forming chiral mononuclear cationic complexes 1 or 2. But in the basic and hydro(solvo)thermal reaction conditions, deprotonated ligands (L)‒ acting as bridges used their terpyridyl and amino acid groups to link with two Co(II) or Ni(II) ions, fabricating chiral dinuclear metallocyclic complexes 3-6. Those chiral mononuclear and dinuclear complexes whose chirality originates in the homochiral ligand HL further self-assemble into higher-dimensional homochiral supramolecular frameworks through intermolecular hydrogen-bonding and π···π interactions. Notably, the coordination mode, hydrogen-bonding site, and existence form of HL ligand can be controlled by the protonation of its amino group, and the architectural diversity of those supramolecular frameworks is adjusted by pH and counter anions. Very interestingly, the 3D porous supramolecular frameworks built up from the huge chiral mononuclear cationic complexes 1 and 2 have novel helical layers only formed through every right-handed helical chain intertwining with two adjacent same helical chains, and the 2D supramolecular helicate 5 consists of two types of left-handed helical chains.

8,10-Diiodo-2,6-dioxo-4λ-ioda-3,5-dioxatricyclo-[5.3.1.0]undeca-1(11),7,9-triene-9-carb-oxy-lic acid.

PubMed

Sheng, Daopeng; Han, Lu; Zhang, Yi; Yang, Yanzhao

2012-03-01

In the title compound, C(9)HI(3)O(6)·2H(2)O, the mol-ecule is located on a twofold axis that gives rise to disorder of the carboxyl group. This disorder is correlated with the disorder of one of the H atoms of the water mol-ecule. The carboxyl group is twisted relative to the attached benzene ring by 75.1 (4)°. The intra-molecular I⋯O distance is 2.112 (6) Å. Mol-ecules are linked via O-H⋯O hydrogen bonding, C-I⋯O halogen bonding, with I⋯O distances in the range 3.156 (5)-3.274 (6) Å, and dipolar C=O⋯C=O inter-actions between the carboxyl and carboxyl-ate groups, with an O⋯C distance of 2.944 (10) Å.

The first 3':5'-cyclic nucleotide-amino acid complex: L-His-cIMP.

PubMed

Slepokura, Katarzyna

2012-08-01

In the crystal structure of the L-His-cIMP complex, i.e. L-histidinium inosine 3':5'-cyclic phosphate [systematic name: 5-(2-amino-2-carboxyethyl)-1H-imidazol-3-ium 7-hydroxy-2-oxo-6-(6-oxo-6,9-dihydro-1H-purin-9-yl)-4a,6,7,7a-tetrahydro-4H-1,3,5,2λ(5)-furo[3,2-d][1,3,2λ(5)]dioxaphosphinin-2-olate], C(6)H(10)N(3)O(2)(+)·C(10)H(10)N(4)O(7)P(-), the Hoogsteen edge of the hypoxanthine (Hyp) base of cIMP and the Hyp face are engaged in specific amino acid-nucleotide (His···cIMP) recognition, i.e. by abutting edge-to-edge and by π-π stacking, respectively. The Watson-Crick edge of Hyp and the cIMP phosphate group play a role in nonspecific His···cIMP contacts. The interactions between the cIMP anions (anti/C3'-endo/trans-gauche/chair conformers) are realized mainly between riboses and phosphate groups. The results for this L-His-cIMP complex, compared with those for the previously reported solvated L-His-IMP crystal structure, indicate a different nature of amino acid-nucleotide recognition and interactions upon the 3':5'-cyclization of the nucleotide phosphate group.

Solvent-mediated secondary building units (SBUs) diversification in a series of MnII-based metal-organic frameworks (MOFs)

NASA Astrophysics Data System (ADS)

Niu, Yan-Fei; Cui, Li-Ting; Han, Jie; Zhao, Xiao-Li

2016-09-01

The role of auxiliary solvents in the formation of MOFs has been investigated for a series of MnII-based framework systems. Reactions of 4,4‧,4″-nitrilotribenzoic acid (H3L) with MnII through varying auxiliary solvents of the medium resulted in the formation of diversified multinuclear MnII subunits in four new coordination polymers: [Mn3(L)(HCOO)3(DEF)3] (1), [Mn3(L)2(EtOH)2]·DMF (2), [Mn5(L)4(H2O)2]·2(H2NMe2)+·4DMF·2H2O (3), and [Mn3(L)2(py)4(H2O)]·H2O (4) (H3L=4,4‧,4‧-nitrilotribenzoic acid, DMF=dimethylformamide, DEF=N,N-diethylformamide, py=pyridine). These four compounds were fully characterized by single-crystal X-ray diffraction, showing interesting SBUs variations. For compound 1, it displays a (3,6)-connected kgd net with wheel [Mn6] cluster serving as SBU, whereas in 2, the sequence of Mn3(COO)9(EtOH)2 is repeated by inversion centers located between Mn1 and Mn3 to form an infinite Mn-carboxylate chain, which are further interlinked by L3- ligands to form a 3D architecture. In 3, the pentanuclear Mn5(CO2)12 clusters are interlinked to form a layer, which are further pillared by L3- to generate a 3D network. Compound 4 has a (3,6)-connected network in which the SBU is a linear trimeric Mn3(COO)6(py)4(H2O) cluster. In addition, the thermal stabilities, X-ray powder diffraction of all the compounds were studied, photoluminescence behaviors of compounds 1, 3 and 4 are discussed.

Characterization of a novel laccase produced by the wood-rotting fungus Phellinus ribis.

PubMed

Min, K L; Kim, Y H; Kim, Y W; Jung, H S; Hah, Y C

2001-08-15

The white-rot fungus Phellinus ribis produced a single form of laccase, which was purified to apparent electrophoretic homogeneity from cultures induced with 2,5-xylidine. This protein was a dimer, consisting of two subunits of 76 kDa as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Carbohydrate analysis revealed that the enzyme contained about 28% carbohydrate content. The laccase appeared to be different from other known laccases by the UV-visible absorption spectrum analysis. One enzyme molecule contained one copper, one manganese, and two zinc atoms. The laccase showed optimal activity at pH 4.0-6.0, 5.0, and 6.0 with 2,6-dimethoxyphenol, ABTS [2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid)], and syringaldazine, respectively. The enzyme preferably oxidized dimethoxyphenol and aromatic amine compounds. The stability of the laccase was low at acidic pH, whereas it showed high stability at neutral pH and mild temperature. The N-terminal amino acid sequence revealed a very low homology with other microbial laccases. With some substrates, the addition of manganese and H2O2 resulted in a remarkable increase in the oxidation rate. Without an appropriate phenolic substrate, the enzyme could not oxidize Mn(II) in the presence of H2O2 or pyrophosphate. Copyright 2001 Academic Press.

Uranium bioprecipitation mediated by yeasts utilizing organic phosphorus substrates.

PubMed

Liang, Xinjin; Csetenyi, Laszlo; Gadd, Geoffrey Michael

2016-06-01

In this research, we have demonstrated the ability of several yeast species to mediate U(VI) biomineralization through uranium phosphate biomineral formation when utilizing an organic source of phosphorus (glycerol 2-phosphate disodium salt hydrate (C3H7Na2O6P·xH2O (G2P)) or phytic acid sodium salt hydrate (C6H18O24P6·xNa(+)·yH2O (PyA))) in the presence of soluble UO2(NO3)2. The formation of meta-ankoleite (K2(UO2)2(PO4)2·6(H2O)), chernikovite ((H3O)2(UO2)2(PO4)2·6(H2O)), bassetite (Fe(++)(UO2)2(PO4)2·8(H2O)), and uramphite ((NH4)(UO2)(PO4)·3(H2O)) on cell surfaces was confirmed by X-ray diffraction in yeasts grown in a defined liquid medium amended with uranium and an organic phosphorus source, as well as in yeasts pre-grown in organic phosphorus-containing media and then subsequently exposed to UO2(NO3)2. The resulting minerals depended on the yeast species as well as physico-chemical conditions. The results obtained in this study demonstrate that phosphatase-mediated uranium biomineralization can occur in yeasts supplied with an organic phosphate substrate as sole source of phosphorus. Further understanding of yeast interactions with uranium may be relevant to development of potential treatment methods for uranium waste and utilization of organic phosphate sources and for prediction of microbial impacts on the fate of uranium in the environment.

Chelation of UO(2)(2+) by vitamin B6 complex derivatives: synthesis and characterization of [UO2(beta-pyracinide)2(H2O)] and [UO2(Pyr2en)DMSO]Cl2{Pyr2en=N,N'-ethylenebis(pyridoxylideneiminato)}. A useful modeling of assimilation of uranium by living beings.

PubMed

Back, Davi Fernando; de Oliveira, Gelson Manzoni; Lang, Ernesto Schulz

2006-10-01

The vitamin B(6) derivatives 4-pyridoxic acid (anionic) and the Schiff base N,N'-ethylenebis(pyridoxylideneiminato) react with UO(2)(NO(3))(2) * 6H(2)O to give [UO(2)(beta-pyracinide)(2)(H(2)O)] (beta-pyracin=4-pyridoxic acid) and [UO(2)(Pyr(2)en)DMSO]Cl(2)(Pyr(2)en=N,N'-ethylenebis(pyridoxylideneiminato); DMSO=dimethyl sulfoxide). In both compounds the two uranyl oxo ligands set the axis of distorted pentagonal bipyramides. The ability of vitamin B(6) derivatives to react with UO(2)(2+) allowing the chelation of one uranium atom represents a very specific model of assimilation of uranium by living beings. It could also explain the serious damages caused by heavy or radioactive metals like uranium since their complexation "in vivo" by enzymatic systems like pyridoxal phosphate-containing enzymes would lead to a modification of the prosthetic groups of the metalloenzymes with loss of their catalytic activities.

Syntheses, structures and luminescent properties of zero-/two-dimensional Cd(II) and Eu(III) complexes

NASA Astrophysics Data System (ADS)

Fan, Rui-Qing; Wang, Li-Yuan; Wang, Ping; Chen, Hong; Sun, Cun-fa; Yang, Yu-Lin; Su, Qing

2012-12-01

Three metal-organic complexes Cd(HBIDC)(phen)2·4H2O (1), [Cd(BIC)(phen)]n (2) and {[Eu(HBIDC)(H2BIDC)(H2O)]·H2O}n (3) (H3BIDC=benzimidazole-5,6-dicarboxylic acid, H2BIC=benzimidazole-6-carboxylic acid, phen=1,10-phenanthroline) have been synthesized under hydro(solvo)thermal conditions and structurally characterized by elemental analysis, IR spectrum, and single-crystal X-ray diffraction. With similar reaction conditions, reactions of the same ligand with different metal cations selected from different blocks (d-block and f-block) result in different coordination modes of carboxylate groups and final frameworks of complexes 1 and 3. The decarboxylation was observed in complex 2 and resulted in the formation of BIC2- ligand. Complexes 1-3 have intense fluorescent emissions at room temperature in dimethylsulfoxide (DMSO) solution and in the solid-state, which indicate they are potential fluorescence materials. The quantum yields and fluorescence lifetimes of these three complexes were systematically studied.

Synthesis, characterization, crystal structure and solution studies of a novel proton transfer (charge transfer) complex of 2,2‧-dipyridylamine with 2,6-pyridine dicarboxylic acid

NASA Astrophysics Data System (ADS)

Ghasemi, Khaled; Rezvani, Ali Reza; Shokrollahi, Ardeshir; Zarghampour, Fereshteh; Moghimi, Abolghasem; García-Granda, Santiago; Mendoza-Meroño, Rafael

2015-06-01

Reaction between 2,2‧-dipyridylamine (DPA) and 2,6-pyridine dicarboxylic acid (dipicolinic acid, dipicH2), in water results in the formation of a proton transfer or charge transfer (CT) complex, (DPAH)+(dipicH)-·H2O, 1. The characterization was performed using 1H NMR and FTIR spectroscopy, elemental analysis and X-ray crystallography. The crystal system is triclinic with space group P1. The structural investigations exhibit that the hydrogen bonds and π-π stacking interactions stabilize the crystal structure of proton transfer complex. The protonation constants of 2,6-pyridine dicarboxylic acid, 2,2‧-dipyridylamine and the equilibrium constants for dipic-DPA (1:1) proton transfer system were calculated by potentiometric pH titration method using Hyperquad2008 program. The stoichiometries of the proton transfer species in solution was in agreement with the solid state result.

Synthesis and characterization of two dehydroacetic acid derivatives and molybdenum(V) complexes: an NMR and crystallographic study

NASA Astrophysics Data System (ADS)

Cindrić, Marina; Vrdoljak, Višnja; Kajfež Novak, Tanja; Ćurić, Manda; Brbot-Šaranović, Ana; Kamenar, Boris

2004-09-01

Two enaminones ethyl 4-(4-hydroxy-6-methyl-2 H-pyran-2-on-3-yl)-2-(tryptamino)-4-oxo-2-butenoate ( HL1) and 3-(1-tryptaminoetylidene)-6-methyl-2 H-pyran-2,4(3H)-dione ( HL2) have been prepared by the reactions of tryptamine with 2-hydroxy-4-(4-hydroxy)-6-methyl)-2 Hbb-pyrane-2-on-3-yl)-4-oxo-2-butenoate (ehmpb) or with dehydroacetic acid (dha). The NMR spectroscopy confirmed that both tautomeric forms of HL1: endo-enol (tautomer A with hydroxyl group at position 4) and exo-enol form (tautomer B with hydroxyl group at position 7) are present in the DMSO- d6 solution. The molecular and crystal structure as well as the NMR data of HL2 showed that the condensation of dha and tryptamine occurs at acetyl-carbonyl and not at the pyrone-carbonyl group. Also new dinuclear [Mo 2O 4(L 1) 2(CH 3OH) 2] ( 1) and hexanuclear molybdenum(V) complexes (C 10H 12NH)[Mo 6O 12(OCH 3) 4(acac) 3] ( 2) have been prepared by the reactions of [Mo 2O 3(acac) 4] (acac=acetilacetonate ion) with HL1 or with tryptamine. All compounds have been characterized also by means of elemental analyses, IR spectroscopy as well as by thermal analyses.

Study of polarized IR spectra of the hydrogen bond system in crystals of styrylacetic acid

NASA Astrophysics Data System (ADS)

Flakus, Henryk T.; Jabłońska, Magdalena; Jones, Peter G.

2006-10-01

We have investigated the polarized IR spectra of the hydrogen bond system in crystals of trans-styrylacetic acid C 6H 5sbnd CH dbnd CH sbnd CH 2sbnd COOH, and also in crystals of the following three deuterium isotopomers of the compound: C 6H 5sbnd CH dbnd CH sbnd CH 2sbnd COOD, C 6H 5sbnd CH dbnd CH sbnd CD 2sbnd COOH and C 6H 5sbnd CH dbnd CH sbnd CD 2sbnd COOD. The spectra were measured at room temperature and at 77 K by a transmission method. The spectral studies were preceded by determination of the X-ray crystal structure. Theoretical analysis of the results concerned linear dichroic effects, the H/D isotopic and temperature effects, observed in the solid-state IR spectra of the hydrogen and of the deuterium bond, at the frequency ranges of the νO sbnd H and the νO sbnd D bands, respectively. Basic spectral properties of the crystals can be interpreted satisfactorily in terms of the " strong-coupling" theory, when based on a hydrogen bond dimer model. This model sufficiently explained not only a two-branch structure of the νO sbnd H and the νO sbnd D bands, and temperature-induced evolution of the crystalline spectra, but also the linear dichroic effects observed in the band frequency ranges. A vibronic mechanism was analyzed, responsible for promotion of the symmetry-forbidden transition in the IR for the totally symmetric proton stretching vibrations in centrosymmetric hydrogen bond dimers. It was found to be of minor importance, when compared with analogous spectral properties of arylcarboxylic acid, or of cinnamic acid crystals. These effects were ascribed to a substantial weakening of electronic couplings between the hydrogen bonds of the associated carboxyl groups and the styryl radicals, associated with the separation of these groups in styrylacetic acid molecules by methylene groups in the molecules.

Antioxidant flavonol glycosides from Schinus molle.

PubMed

Marzouk, Mohamed S; Moharram, Fatma A; Haggag, Eman G; Ibrahim, Magda T; Badary, Osama A

2006-03-01

Chromatographic separation of aqueous MeOH extract of the leaves of Schinus molle L. has yielded two new acylated quercetin glycosides, named isoquercitrin 6''-O-p-hydroxybenzoate (12) and 2''-O-alpha-L-rhamnopyranosyl-hyperin 6''-O-gallate (13), together with 12 known polyphenolic metabolites for the first time from this species, namely gallic acid (1), methyl gallate (2), chlorogenic acid (3), 2''-alpha-L-rhamnopyranosyl-hyperin (4), quercetin 3-O-beta-D-neohesperidoside (5), miquelianin (6), quercetin 3-O-beta-D-galacturonopyranoside (7), isoquercitrin (8), hyperin (9), isoquercitrin 6''-gallate (10), hyperin 6''-O-gallate (11) and (+)-catechin (14). Their structures were established on the basis of chromatographic properties, chemical, spectroscopic (UV, 1H, 13C NMR) and ESI-MS (positive and negative modes) analyses. Compounds 4-9 and 11 exhibited moderate to strong radical scavenging properties on lipid peroxidation, hydroxyl radical and superoxide anion generations with the highest activities shown by 6 and 7 in comparison with that of quercetin as a positive control in vitro. Copyright 2006 John Wiley & Sons, Ltd.

Ligand-controlled assembly of Cd(II) coordination polymers based on mixed ligands of naphthalene-dicarboxylate and dipyrido[3,2-d:2‧,3‧-f]quinoxaline: From 0D+1D cocrystal, 2D rectangular network (4,4), to 3D PtS-type architecture

NASA Astrophysics Data System (ADS)

Liu, Guocheng; Chen, Yongqiang; Wang, Xiuli; Chen, Baokuan; Lin, Hongyan

2009-03-01

Three novel Cd(II) coordination polymers, namely, [Cd(Dpq)(1,8-NDC)(H 2O) 2][Cd(Dpq)(1,8-NDC)]·2H 2O ( 1), [Cd(Dpq)(1,4-NDC)(H 2O)] ( 2), and [Cd(Dpq)(2,6-NDC)] ( 3) have been obtained from hydrothermal reactions of cadmium(II) nitrate with the mixed ligands dipyrido [3,2-d:2',3'-f]quinoxaline (Dpq) and three structurally related naphthalene-dicarboxylate ligands [1,8-naphthalene-dicarboxylic acid (1,8-H 2NDC), 1,4-naphthalene-dicarboxylic acid (1,4-H 2NDC), and 2,6-naphthalene-dicarboxylic acid (2,6-H 2NDC)]. Single-crystal X-ray diffraction analysis reveals that the three polymers exhibit novel structures due to different naphthalene-dicarboxylic acid. Compound 1 is a novel cocrystal of left- and right-handed helical chains and binuclear complexes and ultimately packed into a 3D supramolecular structure through hydrogen bonds and π- π stacking interactions. Compound 2 shows a 2D rectangular network (4,4) bridged by 1,4-NDC with two kinds of coordination modes and ultimately packed into a 3D supramolecular structure through inter-layer π- π stacking interactions. Compound 3 is a new 3D coordination polymer with distorted PtS-type network. In addition, the title compounds exhibit blue/green emission in solid state at room temperature.

First quadruple-glycine bridging mono-lanthanide-substituted borotungstate hybrids.

PubMed

Liu, Jiancai; Yu, Jing; Han, Qing; Wen, Yue; Chen, Lijuan; Zhao, Junwei

2016-10-18

A class of novel organic-inorganic hybrid lanthanide (Ln)-substituted Keggin-type borotungstates K 4 Na 4 H 4 [Ln 2 (gly) 4 (α-BW 11 O 39 ) 2 ]·23H 2 O [Ln = Ce 3+ (1), Pr 3+ (2), Nd 3+ (3), Sm 3+ (4), Eu 3+ (5), Tm 3+ (6); gly = glycine] have been synthesized from the reaction of K 8 [BW 11 O 39 H]·13H 2 O, NaAc·6H 2 O and Ln(NO 3 ) 3 ·6H 2 O by employing gly ligands as structure-stabilizing agents in the conventional aqueous solution system and structurally characterized by elemental analyses, IR spectroscopy, thermogravimetric (TG) analyses, powder X-ray diffraction (PXRD) and single-crystal X-ray diffraction. The common prominent structural feature of isomorphic 1-6 is that all of them consist of two mono-Ln-substituted Keggin [Ln(α-BW 11 O 39 )] 6- fragments linked by four gly ligands, furnishing an intriguing dimeric assembly of the quadruple-gly-connective mono-Ln-substituted borotungstate, in which each carboxylic oxygen atom from gly ligands is bound to Ln 3+ cations in the μ 2 -O or μ 3 -O mode. To the best of our knowledge, 1-6 represent the first examples of inorganic-organic hybrid Ln-substituted borotungstates functionalized by quadruple amino acid bridges. The solid-state photoluminescence properties of 3-5 have been determined at ambient temperature and the photoluminescence emission spectra exhibit the characteristic emission bands derived from Ln 3+ centers. The thermostability of 1-6 has been studied and the thermal decomposition procedure of 3 has been comprehensively investigated with the assistance of variable-temperature PXRD patterns and variable-temperature IR spectra. Furthermore, magnetic susceptibility measurements of 1, 2 and 4 have been conducted.

Crystal structure of 1-(3-chloro­phen­yl)piperazin-1-ium picrate–picric acid (2/1)

PubMed Central

Kavitha, Channappa N.; Jasinski, Jerry P.; Kaur, Manpreet; Anderson, Brian J.; Yathirajan, H. S.

2014-01-01

The title salt {systematic name: bis­[1-(3-chloro­phen­yl)piperazinium 2,4,6-tri­nitro­phenolate]–picric acid (2/1)}, 2C10H14ClN2 +·2C6H5N3O7 −·C6H6N3O7, crystallized with two independent 1-(3-chloro­phen­yl)piperazinium cations, two picrate anions and a picric acid mol­ecule in the asymmetric unit. The six-membered piperazine ring in each cation adopts a slightly distorted chair conformation and contains a protonated N atom. In the picric acid mol­ecule, the mean planes of the nitro groups in the ortho-, meta-, and para-positions are twisted from the benzene ring by 31.5 (3), 7.7 (1), and 3.8 (2)°, respectively. In the anions, the dihedral angles between the benzene ring and the ortho-, meta-, and para-nitro groups are 36.7 (1), 5.0 (6), 4.8 (2)°, and 34.4 (9), 15.3 (8), 4.5 (1)°, respectively. The nitro group in one anion is disordered and was modeled with two sites for one O atom with an occupancy ratio of 0.627 (7):0.373 (7). In the crystal, the picric acid mol­ecule inter­acts with the picrate anion through a trifurcated O—H⋯O four-centre hydrogen bond involving an intra­molecular O—H⋯O hydrogen bond and a weak C—H⋯O inter­action. Weak inter­molecular C—H⋯O inter­actions are responsible for the formation of cation–anion–cation trimers resulting in a chain along [010]. In addition, weak C—H⋯Cl and weak π–π inter­actions [centroid–centroid distances of 3.532 (3), 3.756 (4) and 3.705 (3) Å] are observed and contribute to the stability of the crystal packing. PMID:25484834

A highly sensitive hydrogen peroxide amperometric sensor based on MnO2-modified vertically aligned multiwalled carbon nanotubes.

PubMed

Xu, Bin; Ye, Min-Ling; Yu, Yu-Xiang; Zhang, Wei-De

2010-07-26

In this report, a highly sensitive amperometric sensor based on MnO(2)-modified vertically aligned multiwalled carbon nanotubes (MnO(2)/VACNTs) for determination of hydrogen peroxide (H(2)O(2)) was fabricated by electrodeposition. The morphology of the nanocomposite was characterized by scanning electron microscopy, energy-dispersive X-ray spectrometer and X-ray diffraction. Cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy were applied to investigate the electrochemical properties of the MnO(2)/VACNTs nanocomposite electrode. The mechanism for the electrochemical reaction of H(2)O(2) at the MnO(2)/VACNTs nanocomposite electrode was also discussed. In borate buffer (pH 7.8, 0.20 M), the MnO(2)/VACNTs nanocomposite electrode exhibits a linear dependence (R=0.998) on the concentration of H(2)O(2) from 1.2 x 10(-6)M to 1.8 x 10(-3)M, a high sensitivity of 1.08 x 10(6) microA M(-1) cm(-2) and a detection limit of 8.0 x 10(-7) M (signal/noise=3). Meanwhile, the MnO(2)/VACNTs nanocomposite electrode is also highly resistant towards typical inorganic salts and some biomolecules such as acetic acid, citric acid, uric acid and D-(+)-glucose, etc. In addition, the sensor based on the MnO(2)/VACNTs nanocomposite electrode was applied for the determination of trace of H(2)O(2) in milk with high accuracy, demonstrating its potential for practical application. Copyright 2010 Elsevier B.V. All rights reserved.

Supramolecular architectures in the salt trimethoprimium ferrocene-1-carboxylate and the cocrystal 4-amino-5-chloro-2,6-dimethylpyrimidine-ferrocene-1-carboxylic acid (1/1).

PubMed

Swinton Darious, Robert; Thomas Muthiah, Packianathan; Perdih, Franc

2017-09-01

In the salt trimethoprimium ferrocenecarboxylate [systematic name: 2,4-diamino-5-(3,4,5-trimethoxybenzyl)pyrimidin-1-ium ferrocene-1-carboxylate], (C 14 H 19 N 4 O 3 )[Fe(C 5 H 5 )(C 6 H 4 O 2 )], (I), of the antibacterial compound trimethoprim, the carboxylate group interacts with the protonated aminopyrimidine group of trimethoprim via two N-H...O hydrogen bonds, generating a robust R 2 2 (8) ring motif (heterosynthon). However, in the cocrystal 4-amino-5-chloro-2,6-dimethylpyrimidine-ferrocene-1-carboxylic acid (1/1), [Fe(C 5 H 5 )(C 6 H 5 O 2 )]·C 6 H 8 ClN 3 , (II), the carboxyl-aminopyrimidine interaction [R 2 2 (8) motif] is absent. The carboxyl group interacts with the pyrimidine ring via a single O-H...N hydrogen bond. The pyrimidine rings, however, form base pairs via a pair of N-H...N hydrogen bonds, generating an R 2 2 (8) supramolecular homosynthon. In salt (I), the unsubstituted cyclopentadienyl ring is disordered over two positions, with a refined site-occupation ratio of 0.573 (10):0.427 (10). In this study, the two five-membered cyclopentadienyl (Cp) rings of ferrocene are in a staggered conformation, as is evident from the C...Cg...Cg...C pseudo-torsion angles, which are in the range 36.13-37.53° for (I) and 22.58-23.46° for (II). Regarding the Cp ring of the minor component in salt (I), the geometry of the ferrocene ring is in an eclipsed conformation, as is evident from the C...Cg...Cg...C pseudo-torsion angles, which are in the range 79.26-80.94°. Both crystal structures are further stabilized by weak π-π interactions.

Formation of Amino Acids and Nucleotide Bases in a Titan Atmosphere Simulation Experiment

PubMed Central

Yelle, R.V.; Buch, A.; Carrasco, N.; Cernogora, G.; Dutuit, O.; Quirico, E.; Sciamma-O'Brien, E.; Smith, M.A.; Somogyi, Á.; Szopa, C.; Thissen, R.; Vuitton, V.

2012-01-01

Abstract The discovery of large (>100 u) molecules in Titan's upper atmosphere has heightened astrobiological interest in this unique satellite. In particular, complex organic aerosols produced in atmospheres containing C, N, O, and H, like that of Titan, could be a source of prebiotic molecules. In this work, aerosols produced in a Titan atmosphere simulation experiment with enhanced CO (N2/CH4/CO gas mixtures of 96.2%/2.0%/1.8% and 93.2%/5.0%/1.8%) were found to contain 18 molecules with molecular formulae that correspond to biological amino acids and nucleotide bases. Very high-resolution mass spectrometry of isotopically labeled samples confirmed that C4H5N3O, C4H4N2O2, C5H6N2O2, C5H5N5, and C6H9N3O2 are produced by chemistry in the simulation chamber. Gas chromatography–mass spectrometry (GC-MS) analyses of the non-isotopic samples confirmed the presence of cytosine (C4H5N3O), uracil (C5H4N2O2), thymine (C5H6N2O2), guanine (C5H5N5O), glycine (C2H5NO2), and alanine (C3H7NO2). Adenine (C5H5N5) was detected by GC-MS in isotopically labeled samples. The remaining prebiotic molecules were detected in unlabeled samples only and may have been affected by contamination in the chamber. These results demonstrate that prebiotic molecules can be formed by the high-energy chemistry similar to that which occurs in planetary upper atmospheres and therefore identifies a new source of prebiotic material, potentially increasing the range of planets where life could begin. Key Words: Astrochemistry—Planetary atmospheres—Titan—Astrobiology. Astrobiology 12, 809–817. PMID:22917035

Electrocatalytic H2 production from seawater over Co, N-codoped nanocarbons.

PubMed

Gao, Shuang; Li, Guo-Dong; Liu, Yipu; Chen, Hui; Feng, Liang-Liang; Wang, Yun; Yang, Min; Wang, Dejun; Wang, Shan; Zou, Xiaoxin

2015-02-14

One of the main barriers blocking sustainable hydrogen production is the use of expensive platinum-based catalysts to produce hydrogen from water. Herein we report the cost-effective synthesis of catalytically active, nitrogen-doped, cobalt-encased carbon nanotubes using inexpensive starting materials-urea and cobalt chloride hexahydrate (CoCl2·6H2O). Moreover, we show that the as-obtained nanocarbon material exhibits a remarkable electrocatalytic activity toward the hydrogen evolution reaction (HER); and thus it can be deemed as a potential alternative to noble metal HER catalysts. In particular, the urea-derived carbon nanotubes synthesized at 900 °C (denoted as U-CNT-900) show a superior catalytic activity for HER with low overpotential and high current density in our study. Notably also, U-CNT-900 has the ability to operate stably at all pH values (pH 0-14), and even in buffered seawater (pH 7). The possible synergistic effects between carbon-coated cobalt nanoparticles and the nitrogen dopants can be proposed to account for the HER catalytic activity of U-CNT-900. Given the high natural abundance, ease of synthesis, and high catalytic activity and durability in seawater, this U-CNT-900 material is promising for hydrogen production from water in industrial applications.

Nanocomposites of phosphonic-acid-functionalized polyethylenes with inorganic quantum dots.

PubMed

Rünzi, Thomas; Baier, Moritz C; Negele, Carla; Krumova, Marina; Mecking, Stefan

2015-01-01

Insertion of diethyl vinyl phosphonates and free vinyl phosphonic acid, respectively, into [(P^O)Pd(Me)(dmso)] ((P^O) = κ(2)-P,O-Ar2PC6H4SO2O with Ar = 2-MeOC6H4) (1-dmso) occurs in a 2,1- as well as 1,2-fashion, to form a four-and a five-membered chelate [(P^O)Pd{κ(2)-C,O-CH(P(O)(OR)2)CH2CH3}] and [(P^O)Pd{κ(2)-C,O-CH2CH(P(O)(OR)2)CH3}] (R = H, Et). No decomposition or other reactions of 1 by free phosphonic acid moieties occur. Copolymerization in a pressure reactor by 1-dmso yields linear random poly(ethylene-co-diethyl vinyl phosphonate) and poly(ethylene-co-vinyl phosphonic acid). In these copolymerizations, reversible coordination of the phosphonate moieties of free monomer as well as chelate formation by incorporated monomer retards chain growth as also evidenced by relative binding studies of diethyl phosphonate towards 1. Post-polymerization emulsification of poly(ethylene-co-vinyl phosphonic acid) together with CdSe/CdS quantum dots (QDs) yields submicron (ca. 50 nm from dynamic light scattering (DLS) and transmission electron microscopy (TEM)) polymer particles with the QDs embedded in the functionalized polyethylene in a nonaggregated fashion. This embedding benefits the fluorescence behavior in terms of continuous emission and life-time as revealed by wide-field fluorescence measurements. These composite particle dispersions are employed as a ″masterbatch" together with an aqueous high density polyethylene (HDPE) dispersion to generate thin films (by spin-coating) and bulk materials (from the melt), respectively, in which the inorganic nanoparticles remain highly disperse. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cu(II) coordination polymers constructed by tetrafluoroterephthalic acid and varied imidazole-containing ligands: Syntheses, structures and properties

NASA Astrophysics Data System (ADS)

Liu, Kang; Sun, Yayong; Deng, Liming; Cao, Fan; Han, Jishu; Wang, Lei

2018-02-01

Six new copper(II) coordination polymers combining 2,3,5,6-tetrafluoroterephthalatic acid (H2tfBDC) and diverse imidazole-containing ligands, {[Cu(tfBDC)(1,2-bix)2]·2(H2O)}n (1), {Cu(tfBDC)(Im)2}n (2), {[Cu(1,4-bmimb)2(H2O)]·(tfBDC)·2(H2O)}n (3), {Cu(1,4-bimb)2(H2O)2·(tfBDC)}n (4), {[Cu(1,3-bix)2(H2O)2]·(tfBDC)·6(H2O)}n (5) and {[Cu(1,4-bix)2(H2O)2]·(tfBDC)·(1,4-bix)·4(H2O)}n (6) (1,2-bix = 1,2-bis(imidazole-1-ylmethyl)-benzene, Im = imidazole, 1,4-bmimb = 1,4-bis((2-methyl-1H-imidazol-1-yl)methyl)benzene, 1,4-bimb = 1,4-bis(imidazol-1-yl)-butane, 1,3-bix = 1,3-bis(imidazole-1-ylmethyl)-benzene, 1,4-bix = 1,4-bis(imidazole-1-ylmethyl)-benzene), have been obtained and structurally verified by single-crystal X-ray diffraction analyses and further characterized by powder X-ray diffraction (PXRD), elemental analyses and infrared spectroscopy (IR). Single crystal X-ray diffraction analysis revealed that 1 is 2D 4-connected sql topology (point symbol: {44·62}) based on a single metal ion node. Compound 2 is characterized as an infinite 1D chain structure, which is further extended into a 2D layer through N-H···O hydrogen bonds and then a 3D supramolecular architecture via π···π stacking interactions. Note that 2 was prepared through an in situ ligand reaction in which N,N'-carbonyldiimidazole (cdi) broke up into imidazole ligand. Compound 3 possesses a 3D 4-fold interpenetrated architecture with 4-connected dia topology (Schläfli symbol: {66}) in which tfBDC2- is stabilized in the channel by hydrogen bonds. Compounds 4-6 are all linear 1D coordination polymers. In 4, the free tfBDC2- ligand acts as a μ4-bridge to link four coordinated water molecules from the chain to construct a 2D structure via hydrogen bonds. While in 5 and 6, the uncoordinated tfBDC2- ligands and multimeric water clusters is responsible for the conversion of these 1D coordination polymers into 3D supramolecular assemblies through O-H⋯O hydrogen bonding interactions. Moreover, the UV-vis spectra and thermal stability of 1-6 are discussed in detail.

A one-dimensional zinc(II) coordination polymer with a three-dimensional supramolecular architecture incorporating 1-[(1H-benzimidazol-2-yl)methyl]-1H-tetrazole and adipate.

PubMed

Liu, Chun Li; Huang, Qiu Ying; Meng, Xiang Ru

2016-12-01

The synthesis of coordination polymers or metal-organic frameworks (MOFs) has attracted considerable interest owing to the interesting structures and potential applications of these compounds. It is still a challenge to predict the exact structures and compositions of the final products. A new one-dimensional coordination polymer, catena-poly[[[bis{1-[(1H-benzimidazol-2-yl)methyl]-1H-tetrazole-κN 3 }zinc(II)]-μ-hexane-1,6-dicarboxylato-κ 4 O 1 ,O 1' :O 6 ,O 6' ] monohydrate], {[Zn(C 6 H 8 O 4 )(C 9 H 8 N 6 ) 2 ]·H 2 O} n , has been synthesized by the reaction of Zn(Ac) 2 (Ac is acetate) with 1-[(1H-benzimidazol-2-yl)methyl]-1H-tetrazole (bimt) and adipic acid (H 2 adi) at room temperature. In the polymer, each Zn II ion exhibits an irregular octahedral ZnN 2 O 4 coordination geometry and is coordinated by two N atoms from two symmetry-related bimt ligands and four O atoms from two symmetry-related dianionic adipate ligands. Zn II ions are connected by adipate ligands into a one-dimensional chain which runs parallel to the c axis. The bimt ligands coordinate to the Zn II ions in a monodentate mode on both sides of the main chain. In the crystal, the one-dimensional chains are further connected through N-H...O hydrogen bonds, leading to a three-dimensional supramolecular architecture. In addition, the title polymer exhibits fluorescence, with emissions at 334 and 350 nm in the solid state at room temperature.

An innovative zinc oxide-coated zeolite adsorbent for removal of humic acid

EPA Science Inventory

Zinc oxide (ZnO)-coated zeolite adsorbents were developed by both nitric acid modification and Zn(NO3)2•6H2O functionalization of zeolite. The developed adsorbents were used for the removal of humic acid (HA) from aqueous solutions. The adsorption capacity of the adsorbents at 21...

Organotin(IV) carboxylates based on 2-(1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl)acetic acid: Syntheses, crystal structures, luminescent properties and antitumor activities

NASA Astrophysics Data System (ADS)

Xiao, Xiao; Liang, Jingwen; Xie, Jingyi; Liu, Xin; Zhu, Dongsheng; Dong, Yuan

2017-10-01

Organotin carboxylates based on an amide carboxylic acid 2-(1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl)acetic acid (HL): [(Bn2Sn)2O2L]2·2C6H6 (1) (Bn = benzyl group) and (Ph2Sn)(L)2 (2) were synthesized and characterized by elemental analysis, IR, 1H, 13C, 119Sn NMR spectroscopy and X-ray crystallography diffraction analysis. Complex 1 is dimeric carboxylate tetraorganodistannoxane and show a "ladder-like" molecular structure. Complex 2 is a dialkyltin carboxylate monomer possessing crystallographically imposed two-fold symmetry. Ligand in 1 and 2 adopts unidentate and bidentate coordination respectively. Both 1 and 2 form 1D, 2D and 3D supramolecular organizations in the solid state mediated through Csbnd H⋯O and π⋯π interactions which are discussed in detail. The luminescent properties and preliminary antitumor activities about this series of complexes were also studied.

[Chemical constituents of Swertia angustifolia].

PubMed

He, Kang; Cao, Tuan-wu; Wang, Hong-ling; Geng, Chang-an; Zhang, Xue-mei; Chen, Ji-jun

2015-09-01

This present work is to study the chemical constituents of Swertia angustifolia. The whole plants of air-dried Swertia angustifolia was extracted with 90% EtOH. The water extract was suspended in H2O and extracted with petroleum ether, EtOAc and nBuOH, successively. The compounds were isolated and purified by column chromatography from the EtOAc fraction, and identified based on spectral analyses (MS, 1H-NMR, 13C-NMR). Fourteen compounds were isolated and characterized as 1, 8-dihydroxy-3, 7-dimethoxyxanthone (1), 1, 8-dihydroxy-3, 5, 7-trimethoxyxanthone (2), 7-hydroxy-3, 8-dimethoxyxanthone-1-O-β-D-glucopyranoside (3), 8-0-[β-D-xylopyranosyl-(1-6) -β-D-glucopyranosyl] -1, 7-dihydroxy-3-methoxyxanthone (4), (+) -syringaresinol (5), ferulic acid (6), trans-coniferyl aldehyde (7), sinapaldehyde (8), trans-coniferyl alcohol (9), 3, 4-dihydroxybenzoic acid (10), 2-hydroxybenzoic acid (11), isophthalic acid (12), 2-furoic acid (13), and 2-methyl-4(3H)-quinazolinone(14). Compounds 2-14 were obtained from this plant for the first time.

Preparation, characterisation and study of in vitro biologically active azamacrocyclic Cu(II) dicarboxylate complexes

NASA Astrophysics Data System (ADS)

Antonijević-Nikolić, Mirjana; Antić-Stanković, Jelena; Tanasković, Sladjana B.; Korabik, Maria J.; Gojgić-Cvijović, Gordana; Vučković, Gordana

2013-12-01

New cationic Cu(II) complexes with N, N‧, N″, N″‧-tetrakis(2-pyridylmethyl)-1,4,8,11-tetraazacyclotetradecane (tpmc) and aliphatic dicarboxylic acids: pentanedioic (glutaric acid = glutH2), hexanedioic acid (adipic acid = adipH2) and decanedioic acid (sebacic acid = sebH2) of general formula [Cu4(L)(tpmc)2](ClO4)6·xH2O, L = glut, x = 2; L = adip, x = 7; L = seb, x = 6 were isolated. Their composition and charges are proposed based on elemental analyses and molar conductivity measurements. By the comparison of their UV-Vis, reflectance, FTIR and EPR spectral data, CV and SQUID magnetic measurements, with those for the complex with butanedioic acid (succinic acid = succH2) of known molecular structure and analysis of LC/MS spectra, geometry with two [Cu2tpmc]4+ units bridged by dicarboxylate dianion engaging all oxygens is proposed. Within units, Cu(II) ions are also bridged with N portion of cyclam ring. All four complexes were screened to in vitro antimicrobial and cytotoxic activity along with free primary and secondary ligands, Cu(II) salt and solvent controls. Detected antibacterial and cytotoxic activity for the complexes was enhanced in most cases than the corresponding controls.

Acid-tolerant microaerophilic Fe(II)-oxidizing bacteria promote Fe(III)-accumulation in a fen.

PubMed

Lüdecke, Claudia; Reiche, Marco; Eusterhues, Karin; Nietzsche, Sandor; Küsel, Kirsten

2010-10-01

The ecological importance of Fe(II)-oxidizing bacteria (FeOB) at circumneutral pH is often masked in the presence of O(2) where rapid chemical oxidation of Fe(II) predominates. This study addresses the abundance, diversity and activity of microaerophilic FeOB in an acidic fen (pH ∼ 5) located in northern Bavaria, Germany. Mean O(2) penetration depth reached 16 cm where the highest dissolved Fe(II) concentrations (up to 140 µM) were present in soil water. Acid-tolerant FeOB cultivated in gradient tubes were most abundant (10(6) cells g(-1) peat) at the 10-20 cm depth interval. A stable enrichment culture was active at up to 29% O(2) saturation and Fe(III) accumulated 1.6 times faster than in abiotic controls. An acid-tolerant, microaerophilic isolate (strain CL21) was obtained which was closely related to the neutrophilic, lithoautotrophic FeOB Sideroxydans lithotrophicus strain LD-1. CL21 oxidized Fe(II) between pH 4 and 6.0, and produced nanoscale-goethites with a clearly lower mean coherence length (7 nm) perpendicular to the (110) plane than those formed abiotically (10 nm). Our results suggest that an acid-tolerant population of FeOB is thriving at redox interfaces formed by diffusion-limited O(2) transport in acidic peatlands. Furthermore, this well-adapted population is successfully competing with chemical oxidation and thereby playing an important role in the microbial iron cycle. © 2010 Society for Applied Microbiology and Blackwell Publishing Ltd.

Selective Oxidation of 1,6-Hexanediol to 6-Hydroxycaproic Acid over Reusable Hydrotalcite-Supported Au-Pd Bimetallic Catalysts.

PubMed

Tuteja, Jaya; Nishimura, Shun; Choudhary, Hemant; Ebitani, Kohki

2015-06-08

Selective oxidation of 1,6-hexanediol into 6-hydroxycaproic acid was achieved over hydrotalcite-supported Au-Pd bimetallic nanoparticles as heterogeneous catalyst using aqueous H2 O2 . N,N-dimethyldodecylamine N-oxide (DDAO) was used as an efficient capping agent. Spectroscopic analyses by UV/Vis, TEM, XPS, and X-ray absorption spectroscopy suggested that interactions between gold and palladium atoms are responsible for the high activity of the reusable Au40 Pd60 -DDAO/HT catalyst. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nacystelyn, a novel lysine salt of N-acetylcysteine, to augment cellular antioxidant defence in vitro.

PubMed

Gillissen, A; Jaworska, M; Orth, M; Coffiner, M; Maes, P; App, E M; Cantin, A M; Schultze-Werninghaus, G

1997-03-01

Nacystelyn (NAL), a recently-developed lysine salt of N-acetylcysteine (NAC), and NAG, both known to have excellent mucolytic capabilities, were tested for their ability to enhance cellular antioxidant defence mechanisms. To accomplish this, both drugs were tested in vitro for their capacity: (1) to inhibit O2- and H2O2 in cell-free assay systems; (2) to reduce O2- and H2O2 released by polymorphonuclear leukocytes (PMN); and (3) for their cellular glutathione (GSH) precursor effect. In comparison with GSH, NAL and NAC inhibited H2O2, but not O2-, in cell-free, in vitro test systems in a similar manner. The anti-H2O2 effect of these drugs was as potent as that of GSH, an important antioxidant in mammalian cells. To enhance cellular GSH levels, increasing concentrations (0-2 x 10(-4) mol l-1) of both substances were added to a transformed alveolar cell line (A549 cells). After NAC administration (2 x 10(-4) mol l-1), total intracellular GSH (GSH + 2GSSG) levels reached 4.5 +/- 1.1 x 10(-6) mol per 10(6) cells, whereas NAL increased GSH to 8.3 +/- 1.6 x 10(-6) mol per 10(6) cells. NAC and NAL administration also induced extracellular GSH secretion; about two-fold (NAC), and 1.5-fold (NAL), respectively. The GSH precursor potency of cystine was about two-fold higher than that of NAL and NAC, indicating that the deacetylation process of NAL and NAC slows the ability of both drugs to induce cellular glut production and secretion. Buthionine-sulphoximine, which is an inhibitor of GSH synthetase, blocked the cellular GSH precursor effect of all substances. In addition, these data demonstrate that NAC and NAL reduce H2O2 released by freshly-isolated cultured blood PMN from smokers with chronic obstructive pulmonary disease (COPD) (n = 10) in a similar manner (about 45% reduction of H2O2 activity by NAC or NAL at 4 x 10(-6) mol l-1). In accordance with the results obtained from cell-free, in vitro assays, O2- released by PMN was not affected. Ambroxol (concentrations: 10(-9)-10(-3) mol l-1) did not reduce activity levels of H2O2 and O2- in vitro. Due to the basic effect of dissolved lysine, which separates easily in solution from NAL, the acidic function of the remaining NAC molecule is almost completely neutralized [at concentration 2 x 10(-4) M: pH 3.6 (NAC), pH 6.4 (NAL)]. Due to their function as H2O2 scavengers, and due to their ability to enhance cellular glutathione levels, NAL and NAC both have potent antioxidant capabilities in vitro. The advantage of NAL over NAC is two-fold; it enhances intracellular GSH levels twice as effectively, and it forms neutral pH solutions whereas NAC is acidic. Concluding from these in vitro results, NAL could be an interesting alternative to enhance the antioxidant capacity at the epithelial surface of the lung by aerosol administration.

NMR Spectroscopy and Structural Characterization of Dithiophosphinates Relevant to Minor Actinide Extraction Processes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scott R. Daly; Kevin S. Boland; John R. Klaehn

2012-02-01

Synthetic routes to alkyl and aryl substituted dithiophosphinate salts that contain non-coordinating PPh{sub 4}{sup 1+} counter cations are reported. In general, these compounds can be prepared via a multi-step procedure that starts with reacting secondary phosphines, i.e. HPR{sub 2}, with two equivalents elemental S. This transformation proceeds in two steps - first oxidation of the phosphine and second insertion of S into the H-P bond - and has been used to synthesize a series of dithiophoshinic acids, which were fully characterized, namely HS{sub 2}P(p-CF{sub 3}C{sub 6}H{sub 4}){sub 2}, HS{sub 2}P(m-CF{sub 3}C{sub 6}H{sub 4}){sub 2}, HS{sub 2}P(o-MeC{sub 6}H{sub 4}){sub 2}, andmore » HS{sub 2}P(o-MeOC{sub 6}H{sub 4}){sub 2}. Although the insertion step was found to be much slower than the oxidation reaction, the formation of (NH{sub 4})S{sub 2}PR{sub 2} from HPSR{sub 2} occurs almost instantaneous upon addition of NH{sub 4}OH. Subsequent cation exchange reactions proceed readily with PPh{sub 4}Cl in water, under air, and at ambient conditions to provide analytically pure samples of [PPh{sub 4}][S{sub 2}PR{sub 2}] (R = p-CF{sub 3}C{sub 6}H{sub 4}, m-CF{sub 3}C{sub 6}H{sub 4}, o-CF{sub 3}C{sub 6}H{sub 4}, o-MeC{sub 6}H{sub 4}, o-MeOC{sub 6}H{sub 4}, Ph, and Me, 1b-7b, respectively), which were characterized by elemental analysis, multinuclear NMR, and IR spectroscopy. In addition the S{sub 2}PMe{sub 2}{sup 1-}, S{sub 2}PPh{sub 2}{sup 1-}, and dithiophosphinates with ortho-substituted arene rings were characterized by X-ray crystallography. Structural analysis show that, as opposed to the acids which have short P=S double bonds and long P-SH single bonds, the metric parameters for the S atoms in S{sub 2}PR{sub 2}{sup 1-} are equivalent. In addition, the presence of large non-coordinating PPh{sub 4}{sup 1+} cations guard against intermolecular P-S {hor_ellipsis} X interactions and insure that the P-S bond is isolated. Overall, this synthetic procedure provides high-purity S{sub 2}PR{sub 2}{sup 1-} compounds necessary for subsequent spectroscopic and theoretical studies.« less

Antioxidant and free radical-scavenging activity of constituents from two Scorzonera species.

PubMed

Milella, Luigi; Bader, Ammar; De Tommasi, Nunziatina; Russo, Daniela; Braca, Alessandra

2014-10-01

The aim of this study was to investigate the secondary metabolites content of Scorzonera papposa DC., an edible plant eaten in the desert region of Jordan and to assess its antioxidant and free radical-scavenging activity. By using this bioassay-oriented approach nine compounds, including the new natural compounds (6-trans-p-coumaroyl)-3-O-β-D-glucopyranosyl-2-deoxy-D-riburonic acid (1), (6-cis-p-coumaroyl)-3-O-β-D-glucopyranosyl-2-deoxy-D-riburonic acid (2a), (6-trans-p-coumaroyl)-3-O-β-D-glucopyranosyl-2-deoxy-D-riburonic acid methyl ester (3), and (6-trans-p-coumaroyl)-3-O-β-D-glucopyranosyl-(5-acetyl)-2-deoxy-D-riburonic acid (4), having the rare deoxy-D-riburonic acid moiety, were isolated. Their structures were elucidated by UV, MS, (1)H and (13)C NMR and 2D NMR. The antioxidant activity of the S. papposa pure compounds and of related derivatives isolated from another Scorzonera species (S. judaica Eig.) was also tested. The Relative Antioxidant Capacity Index (RACI) was applied as an integrated method to compare the antioxidant activities obtained using different chemical methods. Copyright © 2014 Elsevier Ltd. All rights reserved.

Benzamide-picric acid (1/1).

PubMed

Sivaramkumar, M S; Velmurugan, R; Sekar, M; Ramesh, P; Ponnuswamy, M N

2010-06-26

In the title compound, C(7)H(7)NO·C(6)H(3)N(3)O(7), one of the nitro groups of the picric acid mol-ecule lies in the plane of the attached benzene ring [dihedral angle = 1.4 (1)°] while the other two are twisted away by 9.9 (1) and 30.3 (1)°. In the benzamide mol-ecule, the amide group is almost coplanar with the benzene ring [dihedral angle = 4.4 (1)°]. An intra-molecular O-H⋯O hydrogen bond generates an S6 ring motif. In the crystal, mol-ecules are linked into a ribbon-like structure along the b axis by O-H⋯O and N-H⋯O inter-molecular hydrogen bonds. In addition, C-H⋯O hydrogen bonds and short O⋯O contacts [2.828 (2) Å] are observed.

Presentation of an experimental method to induce in vitro ("organ chambers") respiratory acidosis and its effect on vascular reactivity.

PubMed

Nadai, Tales Rubens de; Silveira, Ana Paula Cassiano; Monteiro, Ariadne Santana e Neves; Campos, Debora Ribeiro; Carvalho, Marco Tulio Rezende de; Albuquerque, Agnes Afrodite Sumarelli; Celotto, Andrea Carla; Evora, Paulo Roberto Barbosa

2014-11-01

To create in vitro a model to generate acidosis by CO2 bubbling "organ chambers", which would be useful for researchers that aim to study the effects of acid-base disturbs on the endothelium-dependent vascular reactivity. Eighteen male Wistar rats (230-280 g) were housed, before the experiments, under standard laboratory conditions (12h light/dark cycle at 21°C), with free access to food and water. The protocol for promoting in vitro respiratory acidosis was carried out by bubbling increased concentrations of CO2. The target was to achieve an ideal way to decrease the pH gradually to a value of approximately 6.6.It was used, initially, a gas blender varying concentrations of the carbogenic mixture (95% O2 + 5% CO2) and pure CO2. 1) 100% CO2, pH variation very fast, pH minimum 6.0; 2) 90%CO2 pH variation bit slower, pH minimum 6.31; 3) 70%CO2, pH variation slower, pH minimum 6.32; 4) 50% CO2, pH variation slower, pH minimum 6:42; 5) 40 %CO2, Adequate record, pH minimum 6.61, and; 6) 30 %CO2 could not reach values below pH minimum 7.03. Based on these data the gas mixture (O2 60% + CO2 40%) was adopted. This gas mixture (O2 60% + CO2 40%) was effective in inducing respiratory acidosis at a speed that made, possible the recording of isometric force.

The effectiveness of organic PCM based on lauric acid from coconut oil and inorganic PCM based on salt hydrate CaCl2.6H2o as latent heat energy storage system in Indonesia

NASA Astrophysics Data System (ADS)

U, Sri Rahayu A.; Putri, Widya A.; Sutjahja, I. M.; Kurnia, D.; Wonorahardjo, S.

2016-08-01

A latent heat energy storage system utilizing phase change materials (PCM) is an alternative strategy to reduce the use of Air Conditioning (AC) system in big cities in Indonesia in order for energy conservation in the future. In this research we used two kinds of materials, namely organic PCM based on lauric acid from coconut oil (CO) and inorganic PCM based on salt hydrate CaCl2.6H2O, because they have thermophysical parameters suitable for human's thermal comfort application in the building. The CO which contained more than 50% lauric acid has the melting temperature (Tm ) of about 26 °C and heat entalphy (ΔH) around 103 kJ/kg, while CaCl2.6H2O has the melting point of 29 °C and heat entalphy of 190 kJ/kg. In this paper we report the effectiveness of those two kinds of PCM in reducing the air temperature as one of some criteria for human's thermal comfort. The experiments were performed in a close and adiabatic room and the time-temperature measurements were done automatically using Arduino microcontroller and LM35 temperature sensor connected to the PC.

Superposition model analysis of zero field splitting for Mn2+ in some host single crystals

NASA Astrophysics Data System (ADS)

Bansal, R. S.; Ahlawat, P.; Bharti, M.; Hooda, S. S.

2013-07-01

The Newman superposition model has been used to investigate the substitution of Mn2+ for Zn2+ site in ammonium tetra flurozincate dihydrate and for Co2+ site in cobalt ammonium phosphate hexahydrate and cobalt potassium phosphate hexahydrate single crystals. The calculated values of zero field splitting parameter b 2 0 at room temperature fit the experimental data with average intrinsic parameters overline{b}2 (F) = -0.0531 cm-1 for fluorine and overline{b}2 (O) = -0.0280 cm-1 for oxygen, taken t 2 = 7 for Mn2+ doped in ammonium tetra fluorozincate dihydrate single crystals. The values of overline{b}2 determined for Mn2+ doped in cobalt ammonium phosphate hexahydrate are -0.049 cm-1 for site I and -0.045 cm-1 for site II and in cobalt pottasium phosphate hexahydrate single crystals it is found to be overline{b}2 = -0.086 cm-1. We find close agreement between theoretical and experimental values of b 2 0.

{Mo96La8} eggshell ring and self-assembly to {Mo132} Keplerate through Mo-blue intermediate, involved in UV-photolysis of [Mo7O24](6-)/carboxylic acid system at pH 4.

PubMed

Yamase, Toshihiro; Kumagai, Shun; Prokop, Petra V; Ishikawa, Eri; Tomsa, Adrian-Raul

2010-10-18

The prolonged UV-photolysis of aqueous solutions containing [Mo(7)O(24)](6-) and C(2)H(5)CO(2)H (as electron donor) at pH 3.9-4.1 generates the carboxylate-coordinated {Mo(132)} Keplerate (1a) isolated as a formamidinium/ammonium-mixed salt, [HC(NH(2))(2)](26)(NH(4))(28)[Mo(V)(60)Mo(VI)(72)O(372)(H(2)O)(48)(C(2)H(5)CO(2))(36)((i)C(3)H(7)CO(2))(6)]·16H(2)O (1), through the Mo-blue intermediate (2). The coordination of 2 to La(3+) gives rise to the formation of the chain structure of the C(2)-symmetric {Mo(96)La(8)} eggshell rings, formulated by H(22)[Mo(V)(20)Mo(VI)(76)O(301)(H(2)O)(29){La(H(2)O)(6)}(2)]{La(H(2)O)(5)}(6)]·54.5H(2)O (3). The eggshell-ring geometry results from the insertion of [Mo(VI)(2)O(7)(H(2)O)](2-) (spacer) into the equator outer ring of the wheel-shaped Mo-blue, and 10 {(Mo(VI))(Mo(VI)(5))} pentagonal subunits alternately above and below the equator outer ring are connected by eight La(3+) and two {Mo(VI)(2)} linkers within two inner rings. The neighboring eggshell rings are linked through two Mo-O-Mo bonds formed by dehydrative condensation between the {Mo(VI)(2)} linkers to result in the chain structure. Together with the results of the elemental analysis and IR, electronic absorption, (13)C NMR, and ESI-MS spectra for 2, the ring profile analysis of 3 let us identify 2 with a carbolylate-coordinated Mo-blue ring of high nuclearity. The Mo(VI)→Mo(V) photoreductive change of 2 to the 60-electron reduced Keplerate in the presence of C(2)H(5)CO(2)H involves both degradation of the outer ring and splitting of the binuclear linkers, which leads to the formation of [(Mo(VI))Mo(VI)(5)O(21)(H(2)O)(4)(carboxylate)](7-) pentagonal subunits and [Mo(V)(2)O(4)(carboxylate)](+)/[Mo(V)O(2)(carboxylate)(1/2)](0.5+)-mixed linkers for 1.

An Uncommon Carboxyl-Decorated Metal-Organic Framework with Selective Gas Adsorption and Catalytic Conversion of CO2.

PubMed

Li, Yong-Zhi; Wang, Hai-Hua; Yang, Hong-Yun; Hou, Lei; Wang, Yao-Yu; Zhu, Zhonghua

2018-01-19

A new three-dimensional (3D) framework, [Ni(btzip)(H 2 btzip)]⋅2 DMF⋅2 H 2 O (1) (H 2 btzip=4,6-bis(triazol-1-yl)isophthalic acid) as an acidic heterogeneous catalyst was constructed by the reaction of nickel wire and a triazolyl-carboxyl linker. Framework 1 possesses intersected 2D channels decorated by free COOH groups and uncoordinated triazolyl N atoms, leading to not only high CO 2 and C 2 H 6 adsorption capacity but also significant selective capture for CO 2 and C 2 H 6 over CH 4 and CO in 273-333 K. Moreover, 1 reveals chemical stability toward water. Grand Canonical Monte Carlo simulations confirmed the multiple CO 2 - and C 2 H 6 -philic sites. As a result of the presence of accessible Brønsted acidic COOH groups in the channels, the activated framework demonstrates highly efficient catalytic activity in the cycloaddition reaction of CO 2 with propylene oxide/4-chloromethyl-1,3-dioxolan-2-one/3-butoxy-1,2-epoxypropane into cyclic carbonates. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis, characterization and anti-microbial activity of a novel macrocyclic ligand derived from the reaction of 2,6-pyridinedicarboxylic acid with homopiperazine and its Co(II), Ni(II), Cu(II), and Zn(II) complexes

NASA Astrophysics Data System (ADS)

Soleimani, Esmaiel

2011-05-01

The preparation of a novel macrocyclic ligand ( 1), N,N'-diethylhomopiperazinyl,2,6-pyridinedicarboxylate and its Co(II), Ni(II), Cu(II), and Zn(II) complexes are described. The ligand was prepared in EtOH from the reaction of dipotassium salt of 2,6-pyridinedicarboxylic acid with 1,2-dibromoethane in the presence of homopiperazine. Reaction of macrocyclic ligand ( 1) in EtOH with CoCl 2.6H 2O, NiCl 2.6H 2O, CuCl 2.2H 2O, and ZnCl 2·2H 2O yielded the complexes with the general formula [M(L)Cl 2] {where M = Co(II) ( 2), Ni(II) ( 3), Cu(II) ( 4), Zn ( 5), respectively}. The analysis of IR, 1H and 13C NMR spectral data of macrocyclic ligand ( 1) and its Zn(II) complex ( 5) together with their molar conductivity values, and the magnetic moments of the complexes suggest that the macrocyclic ligand ( 1) is bonded to metal(II) ions through two oxygen atoms of ester moiety and the two nitrogen atoms of homopiperazine ring. The electronic spectral data of these complexes in DMSO are in good agreement with the octahedral coordination of M(II) ions. The ligand field parameters for these complexes, i.e. splitting energy and Racah parameter were calculated to be 14,945 and 673 cm -1 for the Co(II) ( 2), 16,260 and 774 cm -1 for the Ni(II) ( 3) complexes respectively. The spliting energy of 17,262 cm -1 was obtained for the Cu(II) complex ( 4).

How pH Modulates the Reactivity and Selectivity of a Siderophore-Associated Flavin Monooxygenase

PubMed Central

2015-01-01

Flavin-containing monooxygenases (FMOs) catalyze the oxygenation of diverse organic molecules using O2, NADPH, and the flavin adenine dinucleotide (FAD) cofactor. The fungal FMO SidA initiates peptidic siderophore biosynthesis via the highly selective hydroxylation of l-ornithine, while the related amino acid l-lysine is a potent effector of reaction uncoupling to generate H2O2. We hypothesized that protonation states could critically influence both substrate-selective hydroxylation and H2O2 release, and therefore undertook a study of SidA’s pH-dependent reaction kinetics. Consistent with other FMOs that stabilize a C4a-OO(H) intermediate, SidA’s reductive half reaction is pH independent. The rate constant for the formation of the reactive C4a-OO(H) intermediate from reduced SidA and O2 is likewise independent of pH. However, the rate constants for C4a-OO(H) reactions, either to eliminate H2O2 or to hydroxylate l-Orn, were strongly pH-dependent and influenced by the nature of the bound amino acid. Solvent kinetic isotope effects of 6.6 ± 0.3 and 1.9 ± 0.2 were measured for the C4a-OOH/H2O2 conversion in the presence and absence of l-Lys, respectively. A model is proposed in which l-Lys accelerates H2O2 release via an acid–base mechanism and where side-chain position determines whether H2O2 or the hydroxylation product is observed. PMID:24490904

Dual shell-like magnetic clusters containing Ni(II) and Ln(III) (Ln = La, Pr, and Nd) ions.

PubMed

Kong, Xiang-Jian; Ren, Yan-Ping; Long, La-Sheng; Zheng, Zhiping; Nichol, Gary; Huang, Rong-Bin; Zheng, Lan-Sun

2008-04-07

Dual shell-like nanoscopic magnetic clusters featuring a polynuclear nickel(II) framework encapsulating that of lanthanide ions (Ln = La, Pr, and Nd) were synthesized using Ni(NO3)(2).6H2O, Ln(NO3)(3).6H2O, and iminodiacetic acid (IDA) under hydrothermal conditions. Structurally established by crystallographic studies, these clusters are [La20Ni30(IDA)30(CO3)6(NO3)6(OH)30(H2O)12](CO3)(6).72H2O (1), [Ln20Ni21(C4H5NO4)21(OH)24(C2H2O3)6(C2O4)3(NO3)9(H2O)12](NO3)9.nH2O [C2H2O3 is the alkoxide form of glycolate; Ln = Pr (2), n = 42; Nd (3), n = 50], and {[La4Ni5Na(IDA)5(CO3)(NO3)4(OH)5(H2O)5][CO3].10H2O} infinity (4). Carbonate, oxalate, and glycolate are products of hydrothermal decomposition of IDA. Compositions of these compounds were confirmed by satisfactory elemental analyses. It has been found that the cluster structure is dependent on the identity of the lanthanide ion as well as the starting Ln/Ni/IDA ratio. The cationic cluster of 1 features a core of the Keplerate type with an outer icosidodecahedron of Ni(II) ions encaging a dodecahedral kernel of La(III). Clusters 2 and 3, distinctly different from 1, are isostructural, possessing a core of an outer shell of 21 Ni(II) ions encapsulating an inner shell of 20 Ln(III) ions. Complex 4 is a three-dimensional assembly of cluster building blocks connected by units of Na(NO3)/La(NO3)3; the structure of the building block resembles closely that of 1, with a hydrated La(III) ion internalized in the decanuclear cage being an extra feature. Magnetic studies indicated ferromagnetic interactions in 1, while overall antiferromagnetic interactions were revealed for 2 and 3. The polymeric, three-dimensional cluster network 4 displayed interesting ferrimagnetic interactions.

21 CFR 184.1195 - Calcium citrate.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium citrate. 184.1195 Section 184.1195 Food and... Substances Affirmed as GRAS § 184.1195 Calcium citrate. (a) Calcium citrate (Ca3(C6H5O7)2·4H2O, CAS Reg. No. 813-0994-095) is the calcium salt of citric acid. It is prepared by neutralizing citric acid with...

21 CFR 184.1751 - Sodium citrate.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Sodium citrate. 184.1751 Section 184.1751 Food and....1751 Sodium citrate. (a) Sodium citrate (C6H5Na3O7·2H2O, CAS Reg. No. 68-0904-092) is the sodium salt of citric acid. It is prepared by neutralizing citric acid with sodium hydroxide or sodium carbonate...

21 CFR 184.1751 - Sodium citrate.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Sodium citrate. 184.1751 Section 184.1751 Food and... Substances Affirmed as GRAS § 184.1751 Sodium citrate. (a) Sodium citrate (C6H5Na3O7·2H2O, CAS Reg. No. 68-0904-092) is the sodium salt of citric acid. It is prepared by neutralizing citric acid with sodium...

21 CFR 184.1751 - Sodium citrate.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Sodium citrate. 184.1751 Section 184.1751 Food and... Substances Affirmed as GRAS § 184.1751 Sodium citrate. (a) Sodium citrate (C6H5Na3O7·2H2O, CAS Reg. No. 68-0904-092) is the sodium salt of citric acid. It is prepared by neutralizing citric acid with sodium...

21 CFR 184.1751 - Sodium citrate.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Sodium citrate. 184.1751 Section 184.1751 Food and... Substances Affirmed as GRAS § 184.1751 Sodium citrate. (a) Sodium citrate (C6H5Na3O7·2H2O, CAS Reg. No. 68-0904-092) is the sodium salt of citric acid. It is prepared by neutralizing citric acid with sodium...

21 CFR 184.1751 - Sodium citrate.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Sodium citrate. 184.1751 Section 184.1751 Food and... Substances Affirmed as GRAS § 184.1751 Sodium citrate. (a) Sodium citrate (C6H5Na3O7·2H2O, CAS Reg. No. 68-0904-092) is the sodium salt of citric acid. It is prepared by neutralizing citric acid with sodium...

21 CFR 184.1195 - Calcium citrate.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Calcium citrate. 184.1195 Section 184.1195 Food... GRAS § 184.1195 Calcium citrate. (a) Calcium citrate (Ca3(C6H5O7)2·4H2O, CAS Reg. No. 813-0994-095) is the calcium salt of citric acid. It is prepared by neutralizing citric acid with calcium hydroxide or...

Tungsten substituted molybdophosphoric acid loaded on various types of mesoporous silica SBA-15 for application of thorium ion adsorption

NASA Astrophysics Data System (ADS)

Aghayan, H.; Khanchi, A. R.; Yousefi, T.; Ghasemi, H.

2017-12-01

In this research, three type of mesoporous silica with different morphologies, namely fibers, spheres and platelets were synthesized and used as a support for immobilization of [H3PMo6W6O40].nH2O. The samples were then applied as an inorganic composite ion-exchanger for sorption of thorium from aqueous solution. Various techniques including ICP, XRD, BET, SEM and FT-IR methods were used to characterize of the products. The experiment results showed that the [H3PMo6W6O40].nH2O supported on the platelet mesoporous silica exhibited both the highest sorption capacity and fastest kinetics when compared with the fibers and spheres adsorbents. Our results show that the morphology of the mesoporous support, which can produce different channel lengths, pore size and surface area, has a serious effect on the sorption properties and influences: (1) the amount of loading of heteropoly acid in the support (2) the kinetic of the sorption process and (3) the maximum of adsorption capacity. The platelet morphology showed the shortest equilibrium time, the highest loading amount and the highest adsorption capacity therefore delivering the best performance among the three morphologies.

Effect of pH and aging time on the kinetic dissociation of 243Am(III) from humic acid-coated gamma-Al2O3: a chelating resin exchange study.

PubMed

Wang, Xiangke; Chen, Changlun; Du, Jinzhou; Tan, Xiaoli; Di, Xu; Yu, Shaoming

2005-09-15

The chelating resin was studied to assess its influence on metal availability and mobility in the environment. The association of organic-inorganic colloid-borne trace elements was investigated in this work. The radionuclide 243Am(III) was chosen as the representative and chemical homologue for trivalent lanthanide and actinide ions present in radioactive nuclear waste. The kinetic dissociation behavior of 243Am(III) from humic acid-coated gamma-Al2O3 was studied at pH values of 4.0 +/- 0.1, 5.0 +/- 0.2, and 6.0 +/- 0.2 with a contact time of 2 days after the addition of a chelating cation exchanger resin. The concentrations of the components were: 243Am(III) 3.0 x 10(-7) mol/L, gamma-Al2O3 0.5 g/L, HA 10 mg/L (pH 4.0 +/- 0.1, 5.0 +/- 0.2, and 6.0 +/- 0.2) and 50 mg/L (pH 6.0 +/- 0.2), respectively. The kinetics of dissociation of 243Am(III) after different equilibration time with humic acid-coated gamma-Al2O3 was also investigated at pH 5.0 +/- 0.2. The experiments were carried out in air and at ambient temperature. The results suggest that the fraction of irreversible bonding of radionuclides to HA-coated Al2O3 increases with increasing pH and is independent of aging time. The assumption of two different 243Am(III)-HA-Al2O3 species, with "fast" and "slow" dissociation kinetics, is required to explain the experimental results. 243Am(III) species present on HA-Al2O3 colloids moves from the "fast" to the "slow" dissociating sites with the increase of aging time.

Positional isomeric tunable two Co(II) 6-connected 3-D frameworks with pentanuclear to binuclear units: structures, ion-exchange and magnetic properties.

PubMed

Han, Min-Le; Duan, Ya-Ping; Li, Dong-Sheng; Wang, Hai-Bin; Zhao, Jun; Wang, Yao-Yu

2014-11-07

Two new Co(II) based metal-organic frameworks, namely {[Co5(μ3-OH)2(m-pda)3(bix)4]·2ClO4}n (1) and {[Co2(p-pda)2(bix)2(H2O)]·H2O}n (2), were prepared by hydrothermal reactions of Co(II) salt with two isomeric dicarboxyl tectons 1,3-phenylenediacetic acid (m-pda) and 1,4-phenylenediacetic acid (p-pda), along with 1,3-bis(imidazol-L-ylmethyl)benzene (bix). Both complexes 1 and 2 have been characterized by elemental analysis, IR spectroscopy, single-crystal X-ray diffraction, powder X-ray diffraction (PXRD), and thermogravimetric analysis (TGA). 1 shows a 6-connected 3-D pcu cationic framework with pentanuclear [Co5(μ3-OH)2(COO)6(bix)2](2+) units, while 2 exhibits a 6-connected 3-D msw net based on [Co2(μ2-H2O)(COO)2](2+) clusters. The results indicate that the different dispositions of the carboxylic groups of dicarboxylates have an important effect on the overall coordination frameworks. Perchlorate anions in 1 can be partly exchanged by thiocyanate and azide anions, however they are unavailable to nitrate anions. Magnetic susceptibility measurements indicate that both 1 and 2 show weak antiferromagnetic interactions between the adjacent Co(II) ions.

Metal aminocarboxylate coordination polymers with chain and layered structures.

PubMed

Dan, Meenakshi; Rao, C N R

2005-11-18

The synthesis and structures of metal aminocarboxylates prepared in acidic, neutral, or alkaline media have been explored with the purpose of isolating coordination polymers with linear chain and two-dimensional layered structures. Metal glycinates of the formulae [CoCl2(H2O)2(CO2CH2NH3)] (I), [MnCl2(CO2CH2NH3)2] (II), and [Cd3Cl6(CO2CH2NH3)4] (III) with one-dimensional chain structures have been obtained by the reaction of the metal salts with glycine in an acidic medium under hydro/solvothermal conditions. These chain compounds contain glycine in the zwitterionic form. 4-Aminobutyric acid transforms to a cyclic amide under such reaction conditions, and the amide forms a chain compound of the formula [CdBr2(C4H7NO)2] (IV). Glycine in the zwitterionic form also forms a two-dimensional layered compound of the formula [Mn(H2O)2(CO2CH2NH3)2]Br2 (V). 6-Aminocaproic acid under alkaline conditions forms layered compounds with metals at room temperature, the metal being coordinated both by the amino nitrogen and the carboxyl oxygen atoms. Of the two layered compounds [Cd{CO2(CH2)5NH2}2]2 H2O (VI) and [Cu{CO2(CH2)5NH2}2]2 H2O (VII), the latter has voids in which water molecules reside.

2-(hydroxymethyl)-1H-benzo[d]imidazole-5-carboxylic acid as linker for Co(II)/Ni(II)/Cu(II) coordination polymers: Synthesis, structures and properties

NASA Astrophysics Data System (ADS)

Wang, Duo-Zhi; Wang, Xin-Fang; Du, Jia-Qiang; Dong, Jun-Liang; Xie, Fei

2018-02-01

We report the synthesis and characterization of five transition metal coordination polymers (CPs) based on M(II) (M: Co, Ni and Cu), 2-(hydroxymethyl)-1H-benzo[d]imidazole-5-carboxylic acid (H2L) ligand. They are formulated as {[Co2(HL)2(H2O)3(SO4)]·H2O}n (1), {[Co2(HL)2(H2O)2]·SiF6}n (2), {[Ni2(HL)2(H2O)3(SO4)]·2H2O}n (3), {[Ni2(HL)2(H2O)4]·H2O·SiF6}n (4), {[Cu2(HL)2(H2O)2]·SiF6}n (5). The complexes 1-5 structure were characterized by single-crystal X-ray diffraction, elemental analyses, infrared spectroscopy (IR), powder X-ray diffraction (PXRD), and thermogravimetric analyses (TGA). Complexes 1-5 are two-dimensional (2D) network type coordination polymers that 1-3, 5 crystallize in monoclinic system within the centrosymmetric space group P2(1)/c, and 4 in triclinic system P-1 space group, they show the same coordination modes (κ1-κ1)-(κ1)-(κ1)-μ3 in coordination polymers. Complexes 1 and 3 expand to three-dimensional framework by means of hydrogen bond interactions, and can be rationalized to be three-connected {63} topological network, while 2, 4, 5 exhibit the topological network with a four-connected {44·62} topological sql network. The luminescent properties (for complexes 1, 2) and UV diffuse reflectance (for complexes 1-5) in the solid state at room temperature were also investigated and discussed. Complexes 1-5 act as effective heterogeneous catalysts, under mild conditions, for the homocoupling reaction of 4-substituted aryl iodides bearing electron-donating groups (-CH3, -OCH3).

Assembling supramolecular networks by halogen bonding in coordination polymers driven by 5-bromonicotinic acid

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gu, Jin-Zhong, E-mail: gujzh@lzu.edu.cn; Wu, Jiang; Kirillov, Alexander M.

2014-05-01

A series of six coordination compounds ([Zn(5-Brnic){sub 2}]·1.5H{sub 2}O){sub n} (1), [Cd(5-Brnic){sub 2}]{sub n} (2), [Co(5-Brnic){sub 2}(H{sub 2}O){sub 2}]{sub n} (3), [Zn(5-Brnic){sub 2}(H{sub 2}biim)]{sub n} (4), ([Cd(5-Brnic){sub 2}(phen)]·H{sub 2}O){sub n} (5), and [Pb(5-Brnic){sub 2}(phen)] (6) have been generated by the hydrothermal method from the metal(II) nitrates, 5-bromonicotinic acid (5-BrnicH), and an optional ancillary 1,10-phenanthroline (phen) or 2,2′-biimidazole (H{sub 2}biim) ligand. All the products 1–6 have been characterized by IR spectroscopy, elemental, thermal, powder and single-crystal X-ray diffraction analyses. Their 5-bromonicotinate-driven structures vary from the 3D metal-organic framework with the seh-3,5-P21/c topology (in 2) and the 2D interdigitated layers with themore » sql topology (in 1 and 3), to the 1D chains (in 4 and 5) and the 0D discrete monomers (in 6). The 5-bromonicotinate moiety acts as a versatile building block and its tethered bromine atom plays a key role in reinforcing and extending the structures into diverse 3D supramolecular networks via the various halogen bonding Br⋯O, Br⋯Br, and Br⋯π interactions, as well as the N–H⋯O and C–H⋯O hydrogen bonds. The obtained results demonstrate a useful guideline toward engineering the supramolecular architectures in the coordination network assembly under the influence of various halogen bonding interactions. The luminescent (for 1, 2, 4, 5, and 6) and magnetic (for 3) properties have also been studied and discussed in detail. - Graphical abstract: Six coordination compounds driven by 5-bromonicotinic acid have been generated and structurally characterized, revealing diverse metal-organic networks that are further reinforced and extended via various halogen bonding interactions. - Highlights: • 5-Bromonicotinic acid is a versatile ligand for Zn, Cd, Co and Pb derivatives. • Careful selection of co-ligands and metals resulted in different network structures. • Halogen and hydrogen bonding interactions lead to various supramolecular networks. • Luminescent and magnetic properties were studied and discussed in detail.« less

Highly efficient and stable catalyst for peroxynitrite decomposition

Treesearch

Yurii V. Geletii; Alan J. Bailey; Jennifer J. Cowan; Ira A. Weinstock; Craig L. Hill

2001-01-01

The new cobalt substituted-polyoxometalate K7[CoAlW11O39]•15H2O and the simple CoCl2•6H2O salt are efficient catalysts for peroxynitrite decomposition. These compounds also catalyze the oxidation of ascorbic acid and the nitration of phenol by peroxynitrite.

Ligand-controlled assembly of Cd(II) coordination polymers based on mixed ligands of naphthalene-dicarboxylate and dipyrido[3,2-d:2',3'-f]quinoxaline: From 0D+1D cocrystal, 2D rectangular network (4,4), to 3D PtS-type architecture

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu Guocheng; Chen Yongqiang; Wang Xiuli

Three novel Cd(II) coordination polymers, namely, [Cd(Dpq)(1,8-NDC)(H{sub 2}O){sub 2}][Cd(Dpq)(1,8-NDC)].2H{sub 2}O (1), [Cd(Dpq)(1,4-NDC)(H{sub 2}O)] (2), and [Cd(Dpq)(2,6-NDC)] (3) have been obtained from hydrothermal reactions of cadmium(II) nitrate with the mixed ligands dipyrido [3,2-d:2',3'-f]quinoxaline (Dpq) and three structurally related naphthalene-dicarboxylate ligands [1,8-naphthalene-dicarboxylic acid (1,8-H{sub 2}NDC), 1,4-naphthalene-dicarboxylic acid (1,4-H{sub 2}NDC), and 2,6-naphthalene-dicarboxylic acid (2,6-H{sub 2}NDC)]. Single-crystal X-ray diffraction analysis reveals that the three polymers exhibit novel structures due to different naphthalene-dicarboxylic acid. Compound 1 is a novel cocrystal of left- and right-handed helical chains and binuclear complexes and ultimately packed into a 3D supramolecular structure through hydrogen bonds and {pi}-{pi} stacking interactions. Compoundmore » 2 shows a 2D rectangular network (4,4) bridged by 1,4-NDC with two kinds of coordination modes and ultimately packed into a 3D supramolecular structure through inter-layer {pi}-{pi} stacking interactions. Compound 3 is a new 3D coordination polymer with distorted PtS-type network. In addition, the title compounds exhibit blue/green emission in solid state at room temperature. - Graphical abstract: Three novel Cd(II) compounds have been synthesized under hydrothermal conditions exhibiting a systematic variation of architecture by the employment of three structurally related naphthalene-dicarboxylate ligands.« less

A luminescent ytterbium(III)-organic framework for highly selective sensing of 2,4,6-trinitrophenol

NASA Astrophysics Data System (ADS)

Xin, Xuelian; Zhang, Minghui; Ji, Shijie; Dong, Hanxiao; Zhang, Liangliang

2018-06-01

An ytterbium(III)-organic framework, [Yb4(abtc)3(HCOO) (H2O)]·(C2H8N) (H2O) (UPC-22, H4abtc = 3,3‧,5,5‧-azobenzene-tetracarboxylic acid) was synthesized under solvothermal conditions and characterized. UPC-22 exhibited strong H4abtc-based luminescence and can be used for sensing nitroaromatic compounds (NACs) in an ethanol suspension with outstanding selectivity and sensitivity. The most striking property of UPC-22 is its ability to selectively detect 2,4,6-trinitrophenol (TNP), thereby rendering it a promising TNP-selective luminescence probe.

Synthesis and structural features of U VI and V IV chelate complexes with (hhmmbH)Cl·H 2O [hhmmb = {3-hydroxyl-5-(hydroxymethyl)-2-methylpyridine-4-yl-methylene}benzohydrazide], a new Schiff base ligand derived from vitamin B6

NASA Astrophysics Data System (ADS)

Back, Davi Fernando; Ballin, Marco Aurélio; de Oliveira, Gelson Manzoni

2009-10-01

The Schiff base ligand {3-hydroxyl-5-(hydroxymethyl)-2-methylpyridine-4-yl-methylene}benzohydrazide hydrochloride monohydrated {(hhmmbH)Cl·H 2O} ( 1) was prepared by reaction of pyridoxine hydrochloride with benzoic acid hydrazide. The reaction of 1 with [VO(acac) 2] and triethylamine yields the neutral vanadium IV complex [VO 2(hhmmb)]·Py ( 2), with a distorted quadratic pyramidal configuration. The Schiff base 1 reacts also with UO 2(NO 3) 2·6H 2O and triethylamine under deprotonation giving the uranium VI cationic complexes [UO 2(hhmmb)(H 2O)Cl] + ( 3) and [UO 2(hhmmb)(CH 3OH)Cl] + ( 4), both showing the classical pentagonal bipyrimidal geometry of UO22+ complexes. The structural features of all compounds are discussed.

Highly efficient and robust molecular ruthenium catalysts for water oxidation.

PubMed

Duan, Lele; Araujo, Carlos Moyses; Ahlquist, Mårten S G; Sun, Licheng

2012-09-25

Water oxidation catalysts are essential components of light-driven water splitting systems, which could convert water to H(2) driven by solar radiation (H(2)O + hν → 1/2O(2) + H(2)). The oxidation of water (H(2)O → 1/2O(2) + 2H(+) + 2e(-)) provides protons and electrons for the production of dihydrogen (2H(+) + 2e(-) → H(2)), a clean-burning and high-capacity energy carrier. One of the obstacles now is the lack of effective and robust water oxidation catalysts. Aiming at developing robust molecular Ru-bda (H(2)bda = 2,2'-bipyridine-6,6'-dicarboxylic acid) water oxidation catalysts, we carried out density functional theory studies, correlated the robustness of catalysts against hydration with the highest occupied molecular orbital levels of a set of ligands, and successfully directed the synthesis of robust Ru-bda water oxidation catalysts. A series of mononuclear ruthenium complexes [Ru(bda)L(2)] (L = pyridazine, pyrimidine, and phthalazine) were subsequently synthesized and shown to effectively catalyze Ce(IV)-driven [Ce(IV) = Ce(NH(4))(2)(NO(3))(6)] water oxidation with high oxygen production rates up to 286 s(-1) and high turnover numbers up to 55,400.

Synthesis, characterization and dissolution of three pharmaceutical cocrystals based on deferiprone

NASA Astrophysics Data System (ADS)

Zhang, Xiaoming; Tian, Yuyang; Jia, Jiangtao; Zhang, Tingting; Zhu, Guangshan

2016-03-01

In this paper we present three new cocrystals based on deferiprone which is the first oral medicine as iron chelator. Solitary deferiprone possesses some known problems due to its good solubility and frequent dosing side effects. For these three novel co crystals, deferiprone is the active pharmaceutical ingredient (API), p-hydroxybenzoic acid (1, C7H9NO2·C7H6O3), 2, 5-dihydroxybenzoic acid (2, C7H9NO2·C7H6O4) and maleic acid (3, C7H9NO2·C4H4O4) are used as cocrystal formers (CCFs), respectively. Their structures were characterized by single crystal X-ray diffraction, powder X-ray diffraction (PXRD) analysis, thermogravimetric analyses (TGA), differential thermal analysis (DTA), elemental analysis (EA) and infrared spectral analysis (IR). Single crystal X-ray diffraction demonstrates that all three cocrystals (1-3) possess strong hydrogen-bondings assembled through hydroxyl of API and carboxylic acids of CCFs. The PXRD results indicate their high purity of as-synthesized samples. TGA, DTA, EA, IR and dissolution study of API and cocrystals were also measured and discussed, respectively. The results suggest that the cocrystals exhibit low dissolution rates comparing with solitary deferiprone, which is very advantageous for the oral medicine with frequent dosing side effects.

Structural characterization of environmentally relevant ternary uranyl citrate complexes present in aqueous solutions and solid state materials.

PubMed

Basile, Madeline; Unruh, Daniel K; Flores, Erin; Johns, Adam; Forbes, Tori Z

2015-02-14

Organic acids are important metal chelators in environmental systems and tend to form soluble complexes in aqueous solutions, ultimately influencing the transport and bioavailability of contaminants in surface and subsurface waters. This is particularly true for the formation of uranyl citrate complexes, which have been utilized in advanced photo- and bioremediation strategies for soils contaminated with nuclear materials. Given the complexity of environmental systems, the formation of ternary or heterometallic uranyl species in aqueous solutions are also expected, particularly with Al(iii) and Fe(iii) cations. These ternary forms are reported to be more stable in aqueous solutions, potentially enhancing contaminant mobility and uptake by organisms, but the exact coordination geometries of these soluble molecular complexes have not been elucidated. To provide insight into the nature of these species, we have developed a series of geochemical model compounds ([(UO(2))(2)Al(2)(C(6)H(4)O(7))(4)](6-) (U(2)Al(2)), [(UO(2))(2)Fe(2)(C(6)H(4)O(7))(4)](6-) (U(2)Fe(2)-1) and [(UO(2))(2)Fe(2)(C(6)H(4)O(7))(4)(H(2)O)(2)](6-) (U(2)Fe(2)-2) and [(UO(2))(2)Fe(4)(OH)(4)(C(6)H(4)O(7))(4)](8-) (U(2)Fe(4))) that were characterized by single-crystal X-ray diffraction and vibrational spectroscopy. Mass spectroscopy was then employed to compare the model compounds to species present in aqueous solutions to provide an enhanced understanding of the ternary uranyl citrate complexes that could be relevant in natural systems.

21 CFR 184.1804 - Sodium potassium tartrate.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Sodium potassium tartrate. 184.1804 Section 184... Listing of Specific Substances Affirmed as GRAS § 184.1804 Sodium potassium tartrate. (a) Sodium potassium tartrate (C4H4KNaO6·4H2O, CAS Reg. No. 304-59-6) is the sodium potassium salt of l−(+)−tartaric acid and is...

21 CFR 184.1804 - Sodium potassium tartrate.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Sodium potassium tartrate. 184.1804 Section 184... as GRAS § 184.1804 Sodium potassium tartrate. (a) Sodium potassium tartrate (C4H4KNaO6·4H2O, CAS Reg. No. 304-59-6) is the sodium potassium salt of l−(+)−tartaric acid and is also called the Rochelle...

21 CFR 184.1804 - Sodium potassium tartrate.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Sodium potassium tartrate. 184.1804 Section 184... Listing of Specific Substances Affirmed as GRAS § 184.1804 Sodium potassium tartrate. (a) Sodium potassium tartrate (C4H4KNaO6·4H2O, CAS Reg. No. 304-59-6) is the sodium potassium salt of l−(+)−tartaric acid and is...

21 CFR 184.1804 - Sodium potassium tartrate.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Sodium potassium tartrate. 184.1804 Section 184... Listing of Specific Substances Affirmed as GRAS § 184.1804 Sodium potassium tartrate. (a) Sodium potassium tartrate (C4H4KNaO6·4H2O, CAS Reg. No. 304-59-6) is the sodium potassium salt of l−(+)−tartaric acid and is...

Reactivity of clay minerals with acids and alkalies

USGS Publications Warehouse

Carroll, Dorothy; Starkey, Harry C.

1971-01-01

One-g samples of a montmorillonite, a metabentonite, an illite, two kaolinites, and three halloysites were treated with 50 ml of hydrochloric acid (6⋅45 N, 1:1), acetic acid (4⋅5 N, 1:3), sodium hydroxide (2⋅8 N), sodium chloride solution (pH 6⋅10; Na = 35‰; Cl = 21⋅5‰), and natural sea water (pH 7⋅85; Na = 35⋅5‰; Cl = 21⋅ 5‰) for a 10-day period in stoppered plastic vials. The supernatant solutions were removed from the clay minerals and analyzed for SiO2, Al2O3, CaO, MgO, Na2O, and K2O. All the solutions removed some SiO2, Al2O3, and Fe2O3 from the samples, but the quantities were small. Sodium hydroxide attacked the kaolin group minerals more strongly than it did montmorillonite, metabentonite, or illite. Halloysite was more strongly attacked by hydrochloric acid than was any of the other experimental minerals. Hydrochloric acid removed iron oxide coatings from soil clay minerals, but acetic acid did not remove them completely. The samples most strongly attacked by HCl and NaOH were examined by X-ray diffraction. Acid treatment did not destroy the structure of the clays, but the halloysite structure was partially destroyed. Sodium hydroxide attacked the halloysite structure, as shown by chemical analysis and X-ray diffraction. These experiments show that treatment in dilute acids has no harmful effect in the preparation of clays for X-ray diffraction. Acetic acid is preferred to hydrochloric acid for this purpose. Hydrochloric acid cleans clay minerals by removing free iron oxide from the surface; acetic acid is less effective.

Humic acid coated Fe3O4 magnetic nanoparticles as highly efficient Fenton-like catalyst for complete mineralization of sulfathiazole.

PubMed

Niu, Hongyun; Zhang, Di; Zhang, Shengxiao; Zhang, Xiaole; Meng, Zhaofu; Cai, Yaqi

2011-06-15

Humic acid coated Fe(3)O(4) magnetic nanoparticles (Fe(3)O(4)/HA) were prepared for the removal of sulfathiazole from aqueous media. Fe(3)O(4)/HA exhibited high activity to produce hydroxyl (OH) radicals through catalytic decomposition of H(2)O(2). The degradation of sulfathiazole was strongly temperature-dependent and favored in acidic solution. The catalytic rate was increased with Fe(3)O(4)/HA dosage and H(2)O(2) concentration. When 3 g L(-1) of Fe(3)O(4)/HA and 0.39 M of H(2)O(2) were introduced to the aqueous solution, most sulfathiazole was degraded within 1h, and >90% of total organic carbon (TOC) were removed in the reaction period (6h). The major final products were identified as environmentally friendly ions or inorganic molecules (SO(4)(2-), CO(2), and N(2)). The corresponding degradation rate (k) of sulfathiazole and TOC was 0.034 and 0.0048 min(-1), respectively. However, when 3 g L(-1) of bare Fe(3)O(4) were used as catalyst, only 54% of TOC was eliminated, and SO(4)(2-) was not detected within 6h. The corresponding degradation rate for sulfathiazole and TOC was 0.01 and 0.0016 min(-1), respectively. The high catalytic ability of Fe(3)O(4)/HA may be caused by the electron transfer among the complexed Fe(II)-HA or Fe(III)-HA, leading to rapid regeneration of Fe(II) species and production of OH radicals. Copyright © 2011 Elsevier B.V. All rights reserved.

Solvent induced synthesis, structure and properties of coordination polymers based on 5-hydroxyisophthalic acid as linker and 1,10-phenanthroline as auxiliary ligand

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kariem, Mukaddus; Yawer, Mohd; Sheikh, Haq Nawaz, E-mail: hnsheikh@rediffmail.com

2015-11-15

Three new coordination polymers [Mn(hip)(phen) (H{sub 2}O)]{sub n} (1), [Co(hip)(phen) (H{sub 2}O)]{sub n} (2), and [Cd(hip) (phen) (H{sub 2}O)]{sub n} (3) (H{sub 2}hip=5-hydroxyisophthalic acid; phen=1,10-phenanthroline) have been synthesized by solvo-hydrothermal method using diethyl formamide-water (DEF-H{sub 2}O) as solvent system. Single-crystal X-ray diffraction analysis reveals that all three coordination polymers 1, 2 and 3 crystallize in monoclinic space group P2/n. Metal ions are inter-connected by hydroxyisophthalate anions forming zig-zag 1D chain. 1D chains are further inter-connected by hydrogen bonding and π–π stacking interactions leading to 3D supramolecular architecture. Hydrogen-bonding and π–π stacking provide thermal stability to polymers. Compounds 1 and 2more » are paramagnetic at room temperature and variable temperature magnetic moment measurements revealed weak ferromagnetic interactions between metal ions at low temperature. Compound 3 exhibits excellent photoluminescence with large Stokes shift. - Graphical abstract: 1D helical chains of coordination polymers were synthesized by solvo-hydrothermal reaction of 5-hydroxyisopthalic acid and 1,10-phenanthroline with MnCl{sub 2}·4H{sub 2}O / CoCl{sub 2}·6H{sub 2}O / Cd(NO{sub 3}){sub 2}·6H{sub 2}O. - Highlights: • Solvent induced synthesis of three coordination polymers with 1D zig-zag structure. • Crystal structures of coordination polymers are reported and discussed. • 1,10-Phenanthroline influences magnetic and luminescent properties of polymers. • Coordination polymer of Cd is luminescent exhibiting large Stokes shift.« less

Sulfated and pyruvylated disaccharide alditols obtained from a red seaweed galactan: ESIMS and NMR approaches.

PubMed

Gonçalves, Alan G; Ducatti, Diogo R B; Duarte, M Eugênia R; Noseda, Miguel D

2002-11-29

The water-soluble acid agaran isolated from Acanthophora spicifera (Rhodophyta) was submitted to alkaline treatment for the complete cyclization of alpha-L-Galp 6-sulfate to 3,6-An-alpha-L-Galp units. The modified agaran was then partially depolymerized using partial reductive hydrolysis. The resulting oligosaccharide mixture was fractionated by adsorption and ion-exchange chromatography. Fractions were purified by gel-filtration chromatography and studied by ESIMS and NMR spectroscopy, including 1D 1H, 13C, DEPT and 2D 1H, 1H COSY, TOCSY and 1H, 13C HMQC procedures. The following neutral, pyruvylated, sulfated and sulfated/pyruvylated disaccharide alditols were obtained: beta-D-Galp-(1-->4)-3,6-An-L-GalOH; 4,6-O-(1-carboxyethylidene)-beta-D-Galp-(1-->4)-3,6-An-L-GalOH; beta-D-Galp 2-sulfate-(1-->4)-3,6-An-L-GalOH and 4,6-O-(1-carboxyethylidene)-beta-D-Galp 2-sulfate-(1-->4)-3,6-An-L-GalOH.

Portable Fiber Laser System and Method to Remove Pits and Cracks on Sensitized Surfaces of Aluminum Alloys

DTIC Science & Technology

2015-08-01

resistant 5083- H116 aluminum, sheet, 1/4" thick, 2" x 24", 2 pieces 71.60 5 Reagent VWR & Fisher Nitric acid and sodium hydroxide for mass loss...Temperature stability ±0.1oC @37oC Temperature uniformity ±0.2oC @37oC 693.55 4 5083-H116 Al-Mg alloy materials McMaster Carr Strengthened corrosion ...test, other acids for etching, electrochemical polishing, and anodizing 700.28 6 Containers VWR Beakers, petri dishes, bottles, graduated cylinders

1H and 13C NMR spectral data of new saponins from Cordia piauhiensis.

PubMed

Santos, Renata P; Silveira, Edilberto R; Uchôa, Daniel Esdras de A; Pessoa, Otília Deusdênia L; Viana, Francisco Arnaldo; Braz-Filho, Raimundo

2007-08-01

Two new bidesmoside triterpenoid saponins were isolated from stems of Cordia piauhiensis. Their structures, characterized as 3-O-alpha-L-rhamnopyranosyl-(1 --> 2)-beta-D-glucopyranosyl pomolic acid 28-O-beta-D-glucopyranosyl ester (1) and 3-O-alpha-L-rhamnopyranosyl-(1 --> 2)-beta-D-glucopyranosyl oleanolic acid 28-O-beta-D-glucopyranosyl-(1 --> 6)-beta-D-glucopyranosyl ester (2), were unequivocally established after extensive NMR (1H, 13C, DEPT 135 degrees, COSY, HSQC, HMBC, TOCSY, and NOESY) studies. Copyright 2007 John Wiley & Sons, Ltd.

Effects of aqueous crude extract of Echeveria gibbiflora on mouse sperm function.

PubMed

Cordero-Martínez, Joaquín; Aguirre-Alvarado, Charmina; Guzmán-Soriano, Jessica Gabriela; Sánchez-Arroyo, Cinthia Erika; Flores-Alonso, Juan Carlos; Rodríguez-Páez, Lorena

2016-10-01

The present study evaluates the possible antifertility effect of aqueous crude extract (OBACE) of Echeveria gibbiflora, a plant that belongs to the crassulaceae family, used in traditional Mexican medicine as a vaginal post coital rinse to prevent pregnancy and shown to have an immobilization/agglutination effect on sperm of different mammal species. We evaluated the effect of OBACE on functional parameters of mouse sperm, such as viability, capacitation, and acrosome reaction. In addition, due to the high concentrations of calcium bis-(hydrogen-1-malate) hexahydrate [Ca (C4H5O5)2•6H2O] present in this plant extract, we evaluated its effect on Ca(2+) influx in mouse sperm under capacitating conditions. Moreover, we determined the acute toxicity of OBACE and its in vivo effect in mouse sperm motility administering a single daily dose of 50 and 100 mg/kg during seven days, intraperitoneally. The sperm viability was not affected by the presence of different concentrations of OBACE, however, the capacitation and acrosome reaction suffered a significant decrease in a concentration-dependent manner, coinciding with the reduction of Ca(2+) influx. Furthermore, OBACE displayed an LD50 of 3,784.42 mg/kg and can be classified as a low toxic substance. Also, in vivo OBACE showed an inhibition of total and progressive motility on mouse sperm alongside a significant decrease of motility kinematic parameters and IVF rates. The results confirm the antifertility effect of this plant used in Mexican folk medicine. Further study on OBACE as a possible contraceptive treatment is warranted because of its activity and low in vivo toxicity. ALH: lateral amplitude; AP: acid phosphatase; BCF: beat frequency; BSA: bovine serum albumine; CTC: chlortetracycline; FDA: fluorescein diacetate; Fura-2 AM: fura-2-acetoxymethyl ester; HIV: human immunodeficiency virus; IVF: in vitro fertilization; OBACE: aqueous crude extract of Echeveria gibbiflora; PI: propidum iodide; SN: supernatant; VAP: average path velocity; VCL: track speed; VSL: straight line velocity.

Enhancement of neurite outgrowth in PC12 cells stimulated with cyclic AMP and NGF by 6-acylated ascorbic acid 2-O-alpha-glucosides (6-Acyl-AA-2G), novel lipophilic ascorbate derivatives.

PubMed

Zhou, Xiaohua; Tai, Akihiro; Yamamoto, Itaru

2003-03-01

It has been shown that ascorbate (AsA) and its stable derivative, ascorbic acid 2-O-alpha-glucoside (AA-2G), do not elicit neurite outgrowth in PC12 cells. However, these ascorbates are synergistically enhanced by both dibutyryl cyclic AMP (Bt(2)cAMP)- and nerve growth factor (NGF)-induced neurite outgrowth in this model. In the present study, the effects of a series of novel lipophilic ascorbate derivatives, 6-acylated ascorbic acid 2-O-alpha-glucosides (6-Acyl-AA-2G), on neurite outgrowth induced by Bt(2)cAMP and NGF were examined in PC12 cells. We found that all the tested acylated ascorbate derivatives enhanced neurite formation induced by both agents in a dose-dependent manner. Of the 6-Acyl-AA-2G derivatives, 6-octanoyl ascorbic acid 2-O-alpha-glucoside (6-Octa-AA-2G) enhanced the Bt(2)cAMP-induced phosphorylated MAPK p44 and p42 expression. A alpha-glucosidase inhibitor, castanospermine, completely abrogated the promotion of neurite outgrowth and MAPK expression by 6-Octa-AA-2G. Addition of 6-Octa-AA-2G (0.5 mM) to PC12 cells caused a rapid and significant increase in intracellular AsA content, which reached a maximum and was maintained from 12 to 24 h after the culture. These findings suggest that 6-Acyl-AA-2G is rapidly hydrolyzed to AsA within the cell and enhances neurite differentiation through the interaction with the inducer-activated MAPK pathway.

Electrospray ionization mass spectrometry of the photodegradation of naphthenic acids mixtures irradiated with titanium dioxide.

PubMed

Headley, John V; Du, Jing-Long; Peru, Kerry M; McMartin, Dena W

2009-05-01

Electrospray ionization mass spectrometry was used to study the photodegradation of an oil sands naphthenic acid (NA) mixture, a commercial Fluka NA mixture and a candidate NA, 4-Methyl-cyclohexaneaceticic acid (4-MCHAA) irradiated with TiO(2) (P25) suspension under both fluorescent and natural sunlight. Under natural sunlight irradiation over the TiO(2) suspension, approximately 75% of compounds in the NA mixtures and 100% of 4-MCHAA were degraded in 8 h. No degradation was observed under dark conditions, regardless of the presence or absence of TiO(2). The structural formula of the NAs is given by C(n)H(2n + z)O(2), where n represents the carbon number and z specifies a homologous family with 0-6 rings (z = 0 to -12). The degree of degradation was noted to vary among the NA mixtures and the candidate NA compound with more efficient degradation achieved for molecules with -z values from 0 to 6. The difference in the efficacy of the photocatalysis was likely due to the structure and size of the compounds. In the case of -z = 6 to 12, steric constraints are a key factor what hinders photocatalysis.

Mechanism of Decarboxylation of Pyruvic Acid in the Presence of Hydrogen Peroxide

PubMed Central

Lopalco, Antonio; Dalwadi, Gautam; Niu, Sida; Schowen, Richard L.; Douglas, Justin; Stella, Valentino J.

2015-01-01

The purpose of this work was to probe the rate and mechanism of rapid decarboxylation of pyruvic acid in the presence of hydrogen peroxide (H2O2) to acetic acid and carbon dioxide over the pH range 2 – 9 at 25°C, utilizing UV spectrophotometry, high performance liquid chromatography (HPLC), and proton and carbon nuclear magnetic resonance spectrometry (1H, 13C-NMR). Changes in UV absorbance at 220 nm were used to determine the kinetics since the reaction was too fast to follow by HPLC or NMR in much of the pH range. The rate constants for the reaction were determined in the presence of molar excess of H2O2 resulting in pseudo first order kinetics. No buffer catalysis was observed. The calculated second order rate constants for the reaction followed a sigmoidal shape with pH independent regions below pH 3 and above pH 7 but increased between pH 4 and 6. Between pH 4 and 9, the results were in agreement with a change from rate determining nucleophilic attack of the deprotonated peroxide species, HOO−, on the α-carbonyl group followed by rapid decarboxylation at pH values below 6 to rate-determining decarboxylation above pH 7. The addition of H2O2 to ethyl pyruvate was also characterized. PMID:26422524

Crystal structures of 4-meth­oxy­benzoic acid–1,3-bis­(pyridin-4-yl)propane (2/1) and biphenyl-4,4′-di­carb­oxy­lic acid–4-meth­oxy­pyridine (1/2)

PubMed Central

Gotoh, Kazuma; Ishida, Hiroyuki

2017-01-01

The crystal structures of two hydrogen-bonded compounds, namely 4-meth­oxy­benzoic acid–1,3-bis­(pyridin-4-yl)propane (2/1), C13H14.59N2·C8H7.67O3·C8H7.74O3, (I), and biphenyl-4,4′-di­carb­oxy­lic acid–4-meth­oxy­pyridine (1/2), C14H9.43O4·C6H7.32NO·C6H7.25NO, (II), have been determined at 93 K. In (I), the asymmetric unit consists of two crystallographically independent 4-meth­oxy­benzoic acid mol­ecules and one 1,3-bis­(pyridin-4-yl)propane mol­ecule. The asymmetric unit of (II) comprises one biphenyl-4,4′-di­carb­oxy­lic acid mol­ecule and two independent 4-meth­oxy­pyridine mol­ecules. In each crystal, the acid and base mol­ecules are linked by short O—H⋯N/N—H⋯O hydrogen bonds, in which H atoms are disordered over the acid O-atom and base N-atom sites, forming a linear hydrogen-bonded 2:1 or 1:2 unit of the acid and the base. The 2:1 units of (I) are linked via C—H⋯π, π–π and C—H⋯O inter­actions into a tape structure along [101], while the 1:2 units of (II) form a double-chain structure along [-101] through π–π and C—H⋯O inter­actions. PMID:28932435

Syntheses, structures and properties of two new organic-inorganic hybrid materials based on ε-Zn Keggin units {ε-PMo(V)8Mo(VI)4O(40-x)(OH)(x)Zn4}.

PubMed

Miao, Hao; Hu, Gonghao; Guo, Jiuyu; Wan, Hongxiang; Mei, Hua; Zhang, Yu; Xu, Yan

2015-01-14

Two novel organic-inorganic hybrids, Na[PMo(V)8Mo(VI)4O38(OH)2Zn4][pyim]2·1.5H2O [ε(pyim)2] (pyim = 2-(2-pyridyl)-imidazole) and [PMo(V)8Mo(VI)4O37(OH)3Zn4]2[pyim]6·4H2O [ε2(pyim)6], based on ε-Zn Keggin units {ε-PMo(V)8Mo(VI)4O(40-x)(OH)(x)Zn4}, have been successfully synthesized under hydrothermal conditions by controlling the pH values. Structural analysis indicates that the framework of ε(pyim)2 is a 1D chain constructed by monomeric ε-Zn units modified by pyim ligands, while ε2(pyim)6 is an isolated structural compound with dimeric ε-Zn units modified by pyim ligands. This is the first isolated structure of the ε-Keggin POMs system. The luminescent and electrochemical properties of ε(pyim)2 and ε2(pyim)6 were investigated. ε2(pyim)6 also shows high catalytic activity for the esterification of phosphoric acid with equimolar lauryl alcohol to monoalkyl phosphate ester (MAP).

Speciation of platinum(IV) in nitric acid solutions.

PubMed

Vasilchenko, Danila; Tkachev, Sergey; Baidina, Iraida; Korenev, Sergey

2013-09-16

The speciation of platinum(IV) ions in nitric acid (6-15.8 M) solutions of H2[Pt(OH)6] has been studied by (195)Pt NMR and Raman spectroscopy. Series of aqua-hydroxo-nitrato complexes [Pt(L)(x)(NO3)(6-x)] (L = H2O or OH(-); x = 0, ..., 6) were found to exist in such solutions. The pair additivity model of chemical shifts and statistical theory were used to assign signals in NMR spectra to particular [Pt(L)(x)(NO3)(6-x)] species. Mononuclear hexanitratoplatinates(IV) have been isolated in solid state in substantial yield as pyridinium salt (PyH)2[Pt(NO3)6] and characterized by single-crystal X-ray diffraction. Aging of the platinum nitric acid solutions for more than 5-6 h results in oligomerization of [Pt(L)(x)(NO3)(6-x)] species and the formation of oligonuclear aqua-hydroxo-nitrato complexes with OH(-) and NO3(-) bridging ligands. Oligomeric platinum(IV) complexes with two and four nuclei were unambiguously detected by NMR on (195)Pt -enriched samples. Oligomers with even higher nuclearity were also detected. Dimeric anions [Pt2(μ-OH)2(NO3)8](2-) have been isolated as single crystals of tetramethylammonium salt and characterized by X-ray diffraction.

Synthesis and physicochemical characterization of carbon backbone modified [Gd(TTDA)(H2O)]2- derivatives.

PubMed

Chang, Ya-Hui; Chen, Chiao-Yun; Singh, Gyan; Chen, Hsing-Yin; Liu, Gin-Chung; Goan, Yih-Gang; Aime, Silvio; Wang, Yun-Ming

2011-02-21

The present study was designed to exploit optimum lipophilicity and high water-exchange rate (k(ex)) on low molecular weight Gd(III) complexes to generate high bound relaxivity (r(1)(b)), upon binding to the lipophilic site of human serum albumin (HSA). Two new carbon backbone modified TTDA (3,6,10-tri(carboxymethyl)-3,6,10-triazadodecanedioic acid) derivatives, CB-TTDA and Bz-CB-TTDA, were synthesized. The complexes [Gd(CB-TTDA)(H(2)O)](2-) and [Gd(Bz-CB-TTDA)(H(2)O)](2-) both display high stability constant (log K(GdL) = 20.28 and 20.09, respectively). Furthermore, CB-TTDA (log K(Gd/Zn) = 4.22) and Bz-CB-TTDA (log K(Gd/Zn) = 4.12) exhibit superior selectivity of Gd(III) against Zn(II) than those of TTDA (log K(Gd/Zn) = 2.93), EPTPA-bz-NO(2) (log K(Gd/Zn) = 3.19), and DTPA (log K(Gd/Zn) = 3.76). However, the stability constant values of [Gd(CB-TTDA)(H(2)O)](2-) and [Gd(Bz-CB-TTDA)(H(2)O)](2-) are lower than that of MS-325. The parameters that affect proton relaxivity have been determined in a combined variable temperature (17)O NMR and NMRD study. The water exchange rates are comparable for the two complexes, 232 × 10(6) s(-1) for [Gd(CB-TTDA)(H(2)O)](2-) and 271 × 10(6) s(-1) for [Gd(Bz-CB-TTDA)(H(2)O)](2-). They are higher than those of [Gd(TTDA)(H(2)O)](2-) (146 × 10(6) s(-1)), [Gd(DTPA)(H(2)O)](2-) (4.1 × 10(6) s(-1)), and MS-325 (6.1 × 10(6) s(-1)). Elevated stability and water exchange rate indicate that the presence of cyclobutyl on the carbon backbone imparts rigidity and steric constraint to [Gd(CB-TTDA)(H(2)O)](2-)and [Gd(Bz-CB-TTDA)(H(2)O)](2-). In addition, the major objective for selecting the cyclobutyl is to tune the lipophilicity of [Gd(Bz-CB-TTDA)(H(2)O)](2-). The binding affinity of [Gd(Bz-CB-TTDA)(H(2)O)](2-) to HSA was evaluated by ultrafiltration study across a membrane with a 30 kDa MW cutoff, and the first three stepwise binding constants were determined by fitting the data to a stoichiometric model. The binding association constants (K(A)) for [Gd(CB-TTDA)(H(2)O)](2-) and [Gd(Bz-CB-TTDA)(H(2)O)](2-) are 1.1 × 10(2) and 1.5 × 10(3), respectively. Although the K(A) value for [Gd(Bz-CB-TTDA)(H(2)O)](2-) is lower than that of MS-325 (K(A) = 3.0 × 10(4)), the r(1)(b) value, r(1)(b) = 66.7 mM(-1) s(-1) for [Gd(Bz-CB-TTDA)(H(2)O)](2-), is significantly higher than that of MS-325 (r(1)(b) = 47.0 mM(-1) s(-1)). As measured by the Zn(II) transmetalation process, the kinetic stabilities of [Gd(CB-TTDA)(H(2)O)](2-), [Gd(Bz-CB-TTDA)(H(2)O)](2-), and [Gd(DTPA)(H(2)O)](2-) are similar and are significantly higher than that of [Gd(DTPA-BMA)(H(2)O)](2-). High thermodynamic and kinetic stability and optimized lipophilicity of [Gd(CB-TTDA)(H(2)O)](2-) make it a favorable blood pool contrast agent for MRI.

Structural modulation and luminescent properties of four Cd{sup II} coordination architectures based on 3-(pyridin-4-yl)-5-(pyrazin-2-yl)-1H-1,2,4-triazole and flexible/rigid dicarboxylate ligands

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xia, Liang; Dong, Wen-Wen, E-mail: dongww1@126.com; Ye, Xiao

To systematically investigate the influence of the flexible or rigid auxiliary ligands on the structures and properties of transition metal compounds, we synthesized four new d{sup 10} coordination polymers (CPs) from 3-(pyridin-4-yl)-5-(pyrazin-2-yl)-1H-1,2,4-triazole (4-Hpzpt) and flexible/rigid dicarboxylate ligands, [Cd(4-pzpt){sub 2}]{sub n} (1), [Cd{sub 3}(4-pzpt){sub 2}(suc){sub 2}]{sub n} (2), [Cd{sub 2}(4-Hpzpt)(nbc){sub 2}(H{sub 2}O)]{sub n} (3) and ([Cd{sub 2}(4-pzpt){sub 2}(tfbdc)(H{sub 2}O){sub 4}]·H{sub 2}O){sub n} (4) (H{sub 2}suc=1,2-ethanedicarboxylic acid, H{sub 2}nbc=hthalene-1,4-dicarboxylic acid, H{sub 2}tfbdc =2,3,5,6-tetrafluoroterephthalic acid). Single crystal X-ray analysis indicates that compound 1 shows a 4{sup 4}-sql layer, which is extended to a 3D network via nonclassical C–H{sup …}N hydrogen bonds. Compound 2more » possesses a 6-connected pcu-4{sup 12}0.6{sup 3} net composed of trinuclear Cd{sup II}-clusters. Compound 3 represents a rare 3D (3,4,4,5)-connected topology with a Schläfli symbol of (4·6·7)(4·5{sup 3}·7{sup 2})(5{sup 3}·6·7·9)(4{sup 2}·5{sup 5}·6·7{sup 2}). Compound 4 exhibits a 2D+2D→2D parallel interpenetrated 6{sup 3}-hcb network. The adjacent 2D networks are interdigitated with each other to form the resulting 3D supramolecular architecture through classical O–H{sup …}N and O–H{sup …}O hydrogen bonds. Structural diversities indicate that the nature of flexible/rigid-dicarboxlates plays crucial roles in modulating structures of these compounds. Moreover, the luminescent properties of them have been briefly investigated. - Graphical abstract: Four new Cd{sup II} coordination architectures constructed from the primary ligand 4-Hpzpt and flexible/rigid dicarboxylate coligands. Structural diversities indicate that the nature of flexible/rigid-dicarboxlates plays crucial roles in modulating structures of these compounds. And more, the thermal stability and luminescence are discussed. - Highlights: • Four new Cd{sup II} compounds with 4-Hpzpt and flexible/rigid dicarboxylate coligands. • Structural analysis of all compounds. • luminescent property of all compounds.« less

Impact of ambient gases on the mechanism of [Cs8Nb6O19]-promoted nerve-agent decomposition† †Dedicated to the memory of Prof. Keiji Morokuma. ‡ ‡Electronic supplementary information (ESI) available: (1) The calculated transition states, intermediates and products of the GB hydrolysis and their important geometry parameters (in Å) for X = SO2, (2) the calculated adsorption energies (in kcal mol–1) of NO2 radicals to Cs8Nb6O19, (3) Cartesian coordinates for all reported structures in xyz format. (structure.xyz). See DOI: 10.1039/c7sc04997h

PubMed Central

Kaledin, Alexey L.; Driscoll, Darren M.; Troya, Diego; Collins-Wildman, Daniel L.

2018-01-01

The impact of ambient gas molecules (X), NO2, CO2 and SO2 on the structure, stability and decontamination activity of Cs8Nb6O19 polyoxometalate was studied computationally and experimentally. It was found that Cs8Nb6O19 absorbs these molecules more strongly than it adsorbs water and Sarin (GB) and that these interactions hinder nerve agent decontamination. The impacts of diamagnetic CO2 and SO2 molecules on polyoxoniobate Cs8Nb6O19 were fundamentally different from that of NO2 radical. At ambient temperatures, weak coordination of the first NO2 radical to Cs8Nb6O19 conferred partial radical character on the polyoxoniobate and promoted stronger coordination of the second NO2 adsorbent to form a stable diamagnetic Cs8Nb6O19/(NO2)2 species. Moreover, at low temperatures, NO2 radicals formed stable dinitrogen tetraoxide (N2O4) that weakly interacted with Cs8Nb6O19. It was found that both in the absence and presence of ambient gas molecules, GB decontamination by the Cs8Nb6O19 species proceeds via general base hydrolysis involving: (a) the adsorption of water and the nerve agent on Cs8Nb6O19/(X), (b) concerted hydrolysis of a water molecule on a basic oxygen atom of the polyoxoniobate and nucleophilic addition of the nascent OH group to the phosphorus center of Sarin, and (c) rapid reorganization of the formed pentacoordinated-phosphorus intermediate, followed by dissociation of either HF or isopropanol and formation of POM-bound isopropyl methyl phosphonic acid (i-MPA) or methyl phosphonofluoridic acid (MPFA), respectively. The presence of the ambient gas molecules increases the energy of the intermediate stationary points relative to the asymptote of the reactants and slightly increases the hydrolysis barrier. These changes closely correlate with the Cs8Nb6O19–X complexation energy. The most energetically stable intermediates of the GB hydrolysis and decontamination reaction were found to be Cs8Nb6O19/X-MPFA-(i-POH) and Cs8Nb6O19/X-(i-MPA)-HF both in the absence and presence of ambient gas molecules. The high stability of these intermediates is due to, in part, the strong hydrogen bonding between the adsorbates and the protonated [Cs8Nb6O19/X/H]+-core. Desorption of HF or/and (i-POH) and regeneration of the catalyst required deprotonation of the [Cs8Nb6O19/X/H]+-core and protonation of the phosphonic acids i-MPA and MPFA. This catalyst regeneration is shown to be a highly endothermic process, which is the rate-limiting step of the GB hydrolysis and decontamination reaction both in the absence and presence of ambient gas molecules. PMID:29719688

Two novel zinc(II) coordination polymers constructed from in situ amidation ligands

NASA Astrophysics Data System (ADS)

Yu, Xiao-Yang; Fu, Yao; Fu, Jian-Tao; Xu, Jia-Ning; Luo, Ya-Nan; Yang, Yan-Yan; Qu, Xiao-Shu; Zhang, Jing; Lu, Shu-Lai

2018-04-01

Two novel coordination compounds, [Zn(Hbimh) (H2O)]·H2O (1) and [Zn(Hbimh)]·(4,4ʹ-bpy)0.5 (2) (H3bimh = benzimidazole-5,6-hydrazide, 4,4ʹ-bpy = 4,4ʹ-bipyridine), have been prepared from the hydrothermal in situ amidation cyclization reactions of H3bimdc (H3bimdc = benzimidazole-5,6-dicarboxylic acid) and hydrazine hydrate (N2H4·H2O). Compound 1 exhibits a one-dimensional (1D) hexagon channel structure. Compound 2 is a three-dimensional (3D) framework structure, with 4,4ʹ-bpy fill the channels. We also obtained the ligand H3bimh. The compounds were characterized by IR, PXRD, TGA and elemental analysis. The fluorescence properties in the solid state at room temperature were also investigated.

Synthesis, structure, and luminescence property of a series of Ag–Ln coordination polymers with the N-heterocyclic carboxylato ligand

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jin, Jing, E-mail: jinjing_crystal@126.com; Chen, Chong; Gao, Yan

Six Ln–Ag coordination polymers {[LnAg_2(IN)_4(H_2O)_5]·NO_3·2H_2O}{sub n} (Ln=Ho (1) and Tb (2), HIN=isonicotinic acid), {[PrAg_2(IN)_4(H_2O)_2]·NO_3·H_2O}{sub n} (3), [LnAg(pdc){sub 2}]{sub n} (Ln=Eu(4) and Pr (5), H{sub 2}pdc=3,4-pyridine-dicarboxylic acid) and [NdAg(bidc){sub 2}(H{sub 2}O){sub 4}]{sub n} (6) (H{sub 2}bidc=benzimidazole-5,6-dicarboxylic acid) have been hydrothermally synthesized and characterized by single crystal X-ray diffraction, elemental analysis, IR, UV–vis-NIR absorption spectra, fluorescence spectra and thermogravimetric analysis. Structural analyses reveal that the six polymers exhibit 0D (polymer (1)), 1D (polymer (2)), 2D (polymers (3) and (5)) and 3D (polymers (4) and (6)) infinite structures, respectively. Polymers (1)–(6) exhibit the Ln(III) characteristic emission in the near-infrared (NIR) region or inmore » the visible region. Especially, the NIR emission bands of polymers 1, 5 and 6 evidently present shift or splitting due to formation of the Ln–Ag coordination polymers. This can be attributed to the tune of inner levels in Ln–Ag system caused by the interact and influence between the 4d orbital of the Ag(I) ion and the 4f orbital of the Ln(III) ion, which can be confirmed by the UV–vis-NIR absorption spectra of the polymers. In addition, the distortion of coordination geometry as well as difference of the coordination number around the Ag(I) ion affect the structure framework. - Graphical abstract: Six Ag–Ln coordination polymers have been hydrothermally synthesized and characterized. The photoluminescence properties were studied. The distortion of coordination geometry of Ag(I) ion affect structure framework. Introduction of Ag(I) cause wonderful changes to the NIR emission of Ln(III) ions. - Highlights: • Six Ln–Ag polymers have been synthesized and characterized. • The distortion of coordination geometry of Ag(I) ion affect structure framework. • Introduction of Ag(I) cause wonderful changes to the NIR emission of Ln(III) ions.« less

Diverse Cd{sup II} coordination complexes derived from bromide isophthalic acid binding with auxiliary N-donor ligands

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, Meng; Dong, Bao-Xia, E-mail: bxdong@yzu.edu.cn; Wu, Yi-Chen

The coordination characteristics of 4-bromoisophthalic acid (4-Br-H{sub 2}ip) have been investigated in a series of Cd{sup II}-based frameworks. Hydrothermal reactions of Cd{sup II} salts and 4-Br-H{sub 2}ip together with flexible or semiflexible N-donor auxiliary ligands resulted in the formation of four three-dimensional coordination complexes with diverse structures: (Cd(bix){sub 0.5}(bix){sub 0.5}(4-Br-ip)]·H{sub 2}O){sub n} (1), [Cd(bbi){sub 0.5}(bbi){sub 0.5}(4-Br-ip)]{sub n} (2), ([Cd(btx){sub 0.5}(4-Br-ip)(H{sub 2}O)]·0.5CH{sub 3}OH·H{sub 2}O){sub n} (3) and ([Cd(bbt){sub 0.5}(4-Br-ip)(H{sub 2}O)]·3·5H{sub 2}O){sub n} (4). These compounds were characterized by elemental analyses, IR spectra, single-crystal and powder X-ray diffraction. They displayed diverse structures depending on the configuration of the 4-connected metal node, themore » coordination mode of the 4-Br-H{sub 2}ip, the coordination ability and conformationally flexibility of the N-donor auxiliary. Compound 1 exhibits 3-fold interpenetrated 6{sup 6} topology and compound 2 has a 4{sup 12} topology. Compounds 3–4 have similar 3D pillar-layered structures based on 3,4-connected binodal net with the Schläfli symbol of (4·3{sup 8}). The thermal stabilities and photoluminescence properties of them were discussed in detail. - Graphical abstract: Four 3D Cd{sup II} coordination complexes on the basis of 4-bromoisophthalic acid (4-Br-H{sub 2}ip) and two types of flexible (bbi, bbt) and semiflexible (bix, btx) N-donor ligands are prepared. They displayed diverse topology structures of 6{sup 6} (1), 4{sup 12} (2) and 4·3{sup 8} (3−4), depending on the configuration of the 4-connected metal node, the coordination mode of the 4-Br-H{sub 2}ip, the coordination ability and conformationally flexibility of the N-donor auxiliary ligand. - Highlights: • Four 3D Cd{sup II} coordination complexes based on 4-Br-H{sub 2}ip and flexible/semiflexible N-donor ligands have been synthesized. • They displayed diverse topology structures of 6{sup 6} for 1, 4{sup 12} for 2 and 4·3{sup 8} for 3–4. • The structural diversity depends on the configuration of 4-Br-H{sub 2}ip and the coordination behaviors of the auxiliary ligand.« less

Syntheses and structure characterization of ten acid-base hybrid crystals based on imidazole derivatives and mineral acids

NASA Astrophysics Data System (ADS)

Hu, Kaikai; Deng, Bowen; Jin, Shouwen; Ding, Aihua; Jin, Shide; Zhu, Jin; Zhang, Huan; Wang, Daqi

2018-04-01

Cocrystallization of the imidazole derivatives with a series of mineral acids gave a total of ten hybrid salts with the compositions: [(H2bzm)(Cl)2·3H2O] (1), [(H2bzm)(ClO4)2] (2), [(H2bze)(Cl)2·2H2O] (3), [(H2bze)(Br)2·2H2O] (4), [(H2bzp)(Cl)2·4H2O] (5), [(H2bzp)(Br)2·4H2O] (6), (2-(imidazol-1-yl)-1-phenylethanone): (phosphoric acid) [(Himpeta)+(H2PO4)-] (7), [(H2impd)(Br)2] (8), [(H2impd)(ClO4)2] (9), and [(Hbzml)(Cl)] (10). The ten salts have been characterised by X-ray diffraction analysis, IR, and elemental analysis, and the melting points of all the salts were also reported. And their structural and supramolecular aspects are fully analyzed. The result reveals that among the ten investigated crystals the ring N atoms of the imidazole are protonated when the acids are deprotonated, and the crystal packing is interpreted in terms of the strong charge-assisted classical H-bonds between the NH+ and deprotonated acidic groups. Further analysis of the crystal packing of the salts indicated that a different set of additional CHsbnd O, CH2sbnd O, CHsbnd Cl, CH2sbnd Cl, CHsbnd N, CHsbnd Br, CH2sbnd Br, Osbnd O, O-π, Br-π, CH-π, and π-π associations contribute to the stabilization and expansion of the total high-dimensional frameworks. For the coexistence of the various weak nonbonding interactions these structures adopted homo or hetero supramolecular synthons or both. Some classical supramolecular synthons, such as R21(7), R22(7), R22(8), and R42(8), usually observed in the organic solids, were again shown to be involved in constructing some of these H-bonding networks.

Aqueous organometallic chemistry. 2. {sup 1}H NMR spectroscopic, synthetic, and structural study of the chemo- and diastereoselective reactions of [Cp{sup *}Rh(H{sub 2}O){sub 3}]{sup 2+} with nitrogen ligands as a function of pH

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ogo, Seiji; Chen, H.; Fish, R.H.

The reactions of a new Cp{sup *}Rh aqua synthon, [Cp{sup *}Rh(H{sub 2}O){sub 3}]{sup 2+} (1), at acidic pH values (2-6) with aniline (2), pyridine (3), and L-phenylalanine (4) have provided interesting chemo- and diastereoselectivities as studied by {sup 1}H NMR, FAB/MS, and single-crystal X-ray crystallography. The reaction of 2 and aqua complex 1, at pH values from 4 to 6, quantitatively provided [Cp{sup *}Rh({eta}{sup 6}-aniline)]{sup 2+} (5); the structure of 5 was unequivocally determined by a single-crystal X-ray analysis, which also showed an approximate 25% {eta}{sup 5} component. Compound 3 reacted with 1, at pH 2-6, to selectively provide [Cp{supmore » *}Rh({eta}{sup 1}-pyridine){sub n} (H{sub 2}O){sub 3-n}]{sup 2+} (n = 1-3) complexes 6a-c as a function of pH. Surprisingly, complex 1 reacted with 4, from pH 4 to 6, to provide only one diastereomer of the known cyclic trimer [(Cp{sup *}Rh)({mu}-{eta}{sup 1}-(OCO):{eta}{sup 2}-(N,OCO)-L-phe nylalanine)]{sub 3}{sup 3+} (7; S{sub C},S{sub C},S{sub C},S{sub Rh},S{sub Rh},S{sub Rh},) an example of a one-step, highly diastereoselective reaction in H{sub 2}O. 8 refs., 4 figs., 2 tabs.« less

Anionic Gallium-Based Metal;#8722;Organic Framework and Its Sorption and Ion-Exchange Properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Banerjee, Debasis; Kim, Sun Jin; Wu, Haohan

2012-04-30

A gallium-based metal-organic framework Ga{sub 6}(C{sub 9}H{sub 3}O{sub 6}){sub 8} {center_dot} (C{sub 2}H{sub 8}N){sub 6}(C{sub 3}H{sub 7}NO){sub 3}(H{sub 2}O){sub 26} [1, Ga{sub 6}(1,3,5-BTC){sub 8} {center_dot} 6DMA {center_dot} 3DMF {center_dot} 26H{sub 2}O], GaMOF-1; BTC = benzenetricarboxylate/trimesic acid and DMA = dimethylamine, with space group I{bar 4}3d, a = 19.611(1) {angstrom}, and V = 7953.4(6) {angstrom}{sup 3}, was synthesized using solvothermal techniques and characterized by synchrotron-based X-ray microcrystal diffraction. Compound 1 contains isolated gallium tetrahedra connected by the organic linker (BTC) forming a 3,4-connected anionic porous network. Disordered positively charged ions and solvent molecules are present in the pore, compensating for themore » negative charge of the framework. These positively charged molecules could be exchanged with alkali-metal ions, as is evident by an ICP-MS study. The H{sub 2} storage capacity of the parent framework is moderate with a H{sub 2} storage capacity of {approx}0.5 wt % at 77 K and 1 atm.« less

Hydrolysis reaction of 2,4-dichlorophenoxyacetic acid. A kinetic and computational study

NASA Astrophysics Data System (ADS)

Romero, Jorge Marcelo; Jorge, Nelly Lidia; Grand, André; Hernández-Laguna, Alfonso

2015-10-01

The degradation of the 2,4-dichlorophenoxyacetic acid in aqueous solution is an hydrolysis reaction. Two products are identified: 2,4-dichlorophenol and glycolic acid. Reaction is investigated as a function of pH and temperature, and it is first-order kinetics and pH-dependent. Reaction is modeled in gas phase, where a proton catalyses the reaction. Critical points of PES are calculated at B3LYP/6-311++G(3df,2p), and aug-cc-pvqz//6-311++G(3df,2p) levels plus ZPE at 6-311++G(3df,2p) level. The activation barrier is 21.2 kcal/mol. Theoretical results agree with the experimental results. A second mechanism related with a Cl2Phsbnd Osbnd CH2sbnd COOH⋯H2O complex is found, but with a rate limiting step of 38.4 kcal/mol.

High-Density Three-Dimension Graphene Macroscopic Objects for High-Capacity Removal of Heavy Metal Ions

PubMed Central

Li, Weiwei; Gao, Song; Wu, Liqiong; Qiu, Shengqiang; Guo, Yufen; Geng, Xiumei; Chen, Mingliang; Liao, Shutian; Zhu, Chao; Gong, Youpin; Long, Mingsheng; Xu, Jianbao; Wei, Xiangfei; Sun, Mengtao; Liu, Liwei

2013-01-01

The chemical vapor deposition (CVD) fabrication of high-density three-dimension graphene macroscopic objects (3D-GMOs) with a relatively low porosity has not yet been realized, although they are desirable for applications in which high mechanical and electrical properties are required. Here, we explore a method to rapidly prepare the high-density 3D-GMOs using nickel chloride hexahydrate (NiCl2·6H2O) as a catalyst precursor by CVD process at atmospheric pressure. Further, the free-standing 3D-GMOs are employed as electrolytic electrodes to remove various heavy metal ions. The robust 3D structure, high conductivity (~12 S/cm) and large specific surface area (~560 m2/g) enable ultra-high electrical adsorption capacities (Cd2+ ~ 434 mg/g, Pb2+ ~ 882 mg/g, Ni2+ ~ 1,683 mg/g, Cu2+ ~ 3,820 mg/g) from aqueous solutions and fast desorption. The current work has significance in the studies of both the fabrication of high-density 3D-GMOs and the removal of heavy metal ions. PMID:23821107

Transformations of lead 1,3-propylenediaminetetraacetate to its MOF products for the selective adsorption of methanol

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dai, Jun-Wei; Li, Xing; Zheng, Jian-Mei

2016-05-15

Water soluble coordination polymer of potassium lead 1,3-propylenediaminetetraacetate {K_4[Pb_2(1,3-pdta)_2]·6H_2O}{sub n} (1) and its insoluble products {[Pb(1,3-H_2pdta)(H_2O)]·2H_2O}{sub n} (2), {[Pb_2(1,3-pdta)(H_2O)_4]·4H_2O}{sub n} (3) and [Pb{sub 2}(1,3-pdta)(H{sub 2}O){sub 2}]{sub n} (4) were obtained from the direct reactions of lead nitrate with 1,3-propylenediaminetetraacetic acid in different conditions (1,3-H{sub 4}pdta=1,3-propylenediaminetetraacetic acid). The former 1 could be converted to the insoluble products of {[Pb_2(1,3-pdta)(H_2O)_4]·4H_2O}{sub n} (3) and [Pb{sub 2}(1,3-pdta)(H{sub 2}O){sub 2}]{sub n} (4) in weak acidic solution. The complexes have been full characterized by EA, FT-IR, solution and solid state {sup 13}C NMR spectra, thermogravimetric and structural analyses. Interestingly, 3 contains a unique (H{sub 2}O){sub 26}more » cluster and a 5.2 Å pore after eliminating the guest water molecules, which exhibits reversible adsorption for methanol. This is confirmed by PXRD and solid state {sup 13}C NMR analyses. Nano-confined methanol in microporous structure has been observed based on the large downfield shift of {sup 13}C NMR signal (Δδ 9.72 ppm), attributing to the methyl group in methanol. - Graphical abstract: Water soluble coordination polymer K{sub 4n}[Pb{sub 2}(1,3-pdta){sub 2}]{sub n}·6nH{sub 2}O (1) is converted to its insoluble product [Pb{sub 2}(1,3-pdta)(H{sub 2}O){sub 4}]{sub n}·4nH{sub 2}O (3), which contains a unique (H{sub 2}O){sub 26} cluster and exhibits reversible adsorption for methanol. - Highlights: • Water-soluble coordination polymer was constructed by lead propylenediaminetetraacetate. • Its MOF product has a unique (H{sub 2}O){sub 26} cluster. • The product exhibits reversible adsorption for methanol.« less

Supramolecular architectures in Co(II) and Cu(II) complexes with thiophene-2-carboxylate and 2-amino-4,6-dimethoxypyrimidine ligands.

PubMed

Karthikeyan, Ammasai; Thomas Muthiah, Packianathan; Perdih, Franc

2016-05-01

The coordination chemistry of mixed-ligand complexes continues to be an active area of research since these compounds have a wide range of applications. Many coordination polymers and metal-organic framworks are emerging as novel functional materials. Aminopyrimidine and its derivatives are flexible ligands with versatile binding and coordination modes which have been proven to be useful in the construction of organic-inorganic hybrid materials and coordination polymers. Thiophenecarboxylic acid, its derivatives and their complexes exhibit pharmacological properties. Cobalt(II) and copper(II) complexes of thiophenecarboxylate have many biological applications, for example, as antifungal and antitumor agents. Two new cobalt(II) and copper(II) complexes incorporating thiophene-2-carboxylate (2-TPC) and 2-amino-4,6-dimethoxypyrimidine (OMP) ligands have been synthesized and characterized by X-ray diffraction studies, namely (2-amino-4,6-dimethoxypyrimidine-κN)aquachlorido(thiophene-2-carboxylato-κO)cobalt(II) monohydrate, [Co(C5H3O2S)Cl(C6H9N3O2)(H2O)]·H2O, (I), and catena-poly[copper(II)-tetrakis(μ-thiophene-2-carboxylato-κ(2)O:O')-copper(II)-(μ-2-amino-4,6-dimethoxypyrimidine-κ(2)N(1):N(3))], [Cu2(C5H3O2S)4(C6H9N3O2)]n, (II). In (I), the Co(II) ion has a distorted tetrahedral coordination environment involving one O atom from a monodentate 2-TPC ligand, one N atom from an OMP ligand, one chloride ligand and one O atom of a water molecule. An additional water molecule is present in the asymmetric unit. The amino group of the coordinated OMP molecule and the coordinated carboxylate O atom of the 2-TPC ligand form an interligand N-H...O hydrogen bond, generating an S(6) ring motif. The pyrimidine molecules also form a base pair [R2(2)(8) motif] via a pair of N-H...N hydrogen bonds. These interactions, together with O-H...O and O-H...Cl hydrogen bonds and π-π stacking interactions, generate a three-dimensional supramolecular architecture. The one-dimensional coordination polymer (II) contains the classical paddle-wheel [Cu2(CH3COO)4(H2O)2] unit, where each carboxylate group of four 2-TPC ligands bridges two square-pyramidally coordinated Cu(II) ions and the apically coordinated OMP ligands bridge the dinuclear copper units. Each dinuclear copper unit has a crystallographic inversion centre, whereas the bridging OMP ligand has crystallographic twofold symmetry. The one-dimensional polymeric chains self-assemble via N-H...O, π-π and C-H...π interactions, generating a three-dimensional supramolecular architecture.

High-Temperature Reactions of Metal Triangles: The Influence of Counterion, Ligand, and Metal on the Structure Observed

NASA Astrophysics Data System (ADS)

Coxall, Robert A.; Parkin, Andrew; Parsons, Simon; Smith, Andrew A.; Timco, Grigore A.; Winpenny, Richard E. P.

2001-07-01

A series of oxo-centered metal carboxylate triangles have been heated to 200-400°C under a stream of N2. The products of this treatment depend on the metal, carboxylate, and counterion present. Heating [Cr3O(O2CC6H4Cl)6(H2O)3][NO3]to 200°C gives a compound that crystallizes as [Cr(OH)(O2CC6H4Cl)2]8 [Cr3O(O2CC6H4Cl)6]2[O2CC6H4Cl], indicating incomplete dehydration of [Cr3O(O2CC6H4Cl)6(H2O)3][NO3] at this temperature. For [Cr3O(O2CCMe3)6][O2CCMe3] heating to 400°C gives a new salt containing the hexanuclear cages [Cr6O2(OH)2(O2CCMe3)11] [Cr6O4(O2CCMe3)11]. For [Mn3O(O2CPh)6(NC5H5)2(H2O)] a reduction of the metal occurs and a polymeric complex [Mn4(O2CPh)8(EtOH)6]n can be crystallized from EtOH.

Zwitterionic and free forms of arylmethyl Meldrum's acids.

PubMed

Mierina, Inese; Mishnev, Anatoly; Jure, Mara

2015-09-01

C-Alkyl (including C-arylmethyl) derivatives of Meldrum's acids are attractive building blocks in organic synthesis, mainly due to the unusually high acidity of the resulting compounds. Three examples, namely 5-[4-(diethylamino)benzyl]-2,2-dimethyl-1,3-dioxane-4,6-dione, C17H23NO4, (I), 2,2-dimethyl-5-(2,4,6-trimethoxybenzyl)-1,3-dioxane-4,6-dione, C16H20O7, (II), and 5-(4-hydroxy-3,5-dimethoxybenzyl)-2,2-dimethyl-1,3-dioxane-4,6-dione, C15H18O7, (III), have been synthesized, characterized by NMR and IR spectroscopy, and studied by single-crystal X-ray structure analysis. The nature of the different substituents resulted in remarkable differences in both the molecular conformations and the crystal packing arrangements. The presence of a substituent with a basic centre in compound (I) leads to the formation of an inner salt accompanied by drastic changes in the conformation of the 1,3-dioxane-4,6-dione fragment. By virtue of strong N-H···O hydrogen bonds, the residues are assembled into infinite chains with the graph-set descriptor C(10). Compound (II) contains methoxy groups in both the ortho- and para-positions of the arylmethyl fragment. Because of the absence of classical hydrogen-bond donors in this structure, the crystal packing is controlled by van der Waals forces and weak C-H···O interactions. Compound (III) contains methoxy groups in both meta-positions and a hydroxy group in the para-position. Supramolecular tetrameric synthons which comprise hydrogen-bonded dimers associated into tetramers through π-π interactions of overlapping benzene rings were observed.

21 CFR 184.1625 - Potassium citrate.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Potassium citrate. 184.1625 Section 184.1625 Food... GRAS § 184.1625 Potassium citrate. (a) Potassium citrate (C6H5K3O7·H2O, CAS Reg. No. 006100-0905-096) is the potassium salt of citric acid. It is prepared by neutralizing citric acid with potassium...

Synthesis, characterization, crystal structure and antimicrobial studies of a novel Cu(II) complex based on itaconic acid and nicotinamide

NASA Astrophysics Data System (ADS)

Tella, Adedibu C.; Owalude, Samson O.; Ajibade, Peter A.; Simon, Nzikahyel; Olatunji, Sunday J.; Abdelbaky, Mohammed S. M.; Garcia-Granda, Santiago

2016-12-01

A novel complex was synthesized from Cu(II), nicotinamide and itaconic acid and is formulated as [Cu(C5H4O4)2(C6H6N2O)2(H2O)2·2(H2O)] (1). The compound was characterized by elemental analysis, FTIR spectroscopy, UV-Vis and single crystal X-ray diffraction. The complex crystallizes in the triclinic P-1 space group, with a = 7.5111(2) Å, b = 9.8529(3) Å, c = 10.5118(4) Å, α = 116.244(3)°, β = 90.291(3)°, γ = 103.335(3)°, V = 673.81(4) Å3, Z = 1.The octahedral geometry around the copper(II) ion is of the form CuN2O4 consisting of two molecules of nicotinamide acting as monodentate ligand through the nitrogen atoms, two molecules itaconate ligand and two coordinated water molecules each coordinating through the oxygen atoms. The structure of 1 showed infinite chains build up linking the molecules together via strong Osbnd H⋯O and Nsbnd H⋯O intermolecular hydrogen bonds generating a two dimensional network sheet along c axis. The antimicrobial study of the synthesized complex 1 was investigated and showed higher antibacterial activity against all the organisms comparing with Copper(II) nicotinamide 2 and Copper(II) itaconate 3.

A study on the dissolution rates of K-Cr(VI)-jarosites: kinetic analysis and implications.

PubMed

Reyes, Iván A; Mireles, Ister; Patiño, Francisco; Pandiyan, Thangarasu; Flores, Mizraim U; Palacios, Elia G; Gutiérrez, Emmanuel J; Reyes, Martín

2016-01-01

The presence of natural and industrial jarosite type-compounds in the environment could have important implications in the mobility of potentially toxic elements such as lead, mercury, arsenic, chromium, among others. Understanding the dissolution reactions of jarosite-type compounds is notably important for an environmental assessment (for water and soil), since some of these elements could either return to the environment or work as temporary deposits of these species, thus would reduce their immediate environmental impact. This work reports the effects of temperature, pH, particle diameter and Cr(VI) content on the initial dissolution rates of K-Cr(VI)-jarosites (KFe3[(SO4)2 - X(CrO4)X](OH)6). Temperature (T) was the variable with the strongest effect, followed by pH in acid/alkaline medium (H3O(+)/OH(-)). It was found that the substitution of CrO4 (2-)in Y-site and the substitution of H3O(+) in M-site do not modify the dissolution rates. The model that describes the dissolution process is the unreacted core kinetic model, with the chemical reaction on the unreacted core surface. The dissolution in acid medium was congruent, while in alkaline media was incongruent. In both reaction media, there is a release of K(+), SO4 (2-) and CrO4 (2-) from the KFe3[(SO4)2 - X(CrO4)X](OH)6 structure, although the latter is rapidly absorbed by the solid residues of Fe(OH)3 in alkaline medium dissolutions. The dissolution of KFe3[(SO4)2 - X(CrO4)X](OH)6 exhibited good stability in a wide range of pH and T conditions corresponding to the calculated parameters of reaction order n, activation energy E A and dissolution rate constants for each kinetic stages of induction and progressive conversion. The kinetic analysis related to the reaction orders and calculated activation energies confirmed that extreme pH and T conditions are necessary to obtain considerably high dissolution rates. Extreme pH conditions (acidic or alkaline) cause the preferential release of K(+), SO4 (2-) and CrO4 (2-) from the KFe3[(SO4)2 - X(CrO4)X](OH)6 structure, although CrO4 (2-) is quickly adsorbed by Fe(OH)3 solid residues. The precipitation of phases such as KFe3[(SO4)2 - X(CrO4)X](OH)6, and the absorption of Cr(VI) after dissolution can play an important role as retention mechanisms of Cr(VI) in nature.

Intercalation and controlled release of 2,4-dichlorophenoxyacetic acid using rhombohedral [LiAl2(OH)6]Cl·xH2O

NASA Astrophysics Data System (ADS)

Ragavan, Anusha; Khan, Aamir I.; O'Hare, Dermot

2006-05-01

2,4-Dichlorophenoxyacetic acid (2,4-D) has been fully intercalated into the rhombohedral polymorph of [LiAl2(OH)6]Cl·xH2O ([rhom-Li Al] LDH) by an ion exchange method. The controlled release of 2,4-D from the interlamellar spaces of [rhom-Li Al] LDH has been studied in a phosphate buffer, natural rainwater and deionised water. In buffer solution and rainwater, the intercalated herbicide is exchanged for anions in solution. In contrast, in deionised water the herbicide is released as part of the Li+/herbicide ion pair, leading to the formation of Al(OH)3 and the solvated ions.

Copper(II) ion catalytic oxidation of o-phenylenediamine and characterization, X-ray crystal structure and solution studies of the final product [DAPH][H3O][Cu(dipic)2]·3H2O

NASA Astrophysics Data System (ADS)

Ghasemi, Khaled; Rezvani, Ali Reza; Shokrollahi, Ardeshir; Abdul Razak, Ibrahim; Refahi, Masoud; Moghimi, Abolghasem; Rosli, Mohd Mustaqim

2015-09-01

The complex [DAPH][H3O][Cu(dipic)2]·3H2O, (1) (dipicH2 = 2,6-pyridinedicarboxylic acid and DAP = 2,3-diaminophenazine) was prepared from the reaction of Cu(NO3)2·2H2O with mixture of o-phenylenediamine (OPD) and 2,6-pyridinedicarboxylic acid in water. The complex was characterized by FTIR, elemental analysis, UV-Vis and the single-crystal X-ray diffraction. The crystal system is monoclinic with the space group P21/c. This complex is stabilized in the solid state by an extensive network of hydrogen bonds between crystallized water, anionic and cationic fragments, which form a three-dimensional network. Furthermore, hydrogen bonds, π⋯π and Csbnd O⋯π stacking interactions seem to be effective in stabilizing the crystal structures. The protonation constants of dipic (L) and DAP (Q), the equilibrium constants for the dipic-DAP proton transfer system and the stoichiometry and stability constants of binary complexes including each of ligands (dipic, DAP) in presence Cu2+ ion, ternary complexes including, both of ligands (dipic-DAP) in presence of metal ion were calculated in aqueous solutions by potentiometric pH titration method using the Hyperquad2008 program. The stoichiometry of the most complexes species in solution was found to be very similar to the solid-state of cited metal ion complex.

Thermal energy storage for low grade heat in the organic Rankine cycle

NASA Astrophysics Data System (ADS)

Soda, Michael John

Limits of efficiencies cause immense amounts of thermal energy in the form of waste heat to be vented to the atmosphere. Up to 60% of unrecovered waste heat is classified as low or ultra-low quality, making recovery difficult or inefficient. The organic Rankine cycle can be used to generate mechanical power and electricity from these low temperatures where other thermal cycles are impractical. A variety of organic working fluids are available to optimize the ORC for any target temperature range. San Diego State University has one such experimental ORC using R245fa, and has been experimenting with multiple expanders. One limitation of recovering waste heat is the sporadic or cyclical nature common to its production. This inconsistency makes sizing heat recovery ORC systems difficult for a variety of reasons including off-design-point efficiency loss, increased attrition from varying loads, unreliable outputs, and overall system costs. Thermal energy storage systems can address all of these issues by smoothing the thermal input to a constant and reliable level and providing back-up capacity for times when the thermal input is deactivated. Multiple types of thermal energy storage have been explored including sensible, latent, and thermochemical. Latent heat storage involves storing thermal energy in the reversible phase change of a phase change material, or PCM, and can have several advantages over other modalities including energy storage density, cost, simplicity, reliability, relatively constant temperature output, and temperature customizability. The largest obstacles to using latent heat storage include heat transfer rates, thermal cycling stability, and potentially corrosive PCMs. Targeting 86°C, the operating temperature of SDSU's experimental ORC, multiple potential materials were explored and tested as potential PCMs including Magnesium Chloride Hexahydrate (MgCl2˙6H2O), Magnesium Nitrate Hexahydrate (Mg(NO3)2˙6H 2O), montan wax, and carnauba wax. The addition of graphite to augment heat transfer rates was also tested. Melting and solidification temperatures largely matched predictions. The magnesium salts were found to be less stable under thermal cycling than the waxes. Graphite was only soluble in the waxes. Mixtures of magnesium salts and waxes yielded a layered composite with the less dense waxes creating a sealing layer over the salt layer that significantly increased the stability of the magnesium salts. Research into optimum heat exchangers and storage vessels for these applications indicates that horizontally oriented aluminum pipes with vertically oriented aluminum fins would be the best method of storing and retrieving energy. Fin spacing can be predicted by an equation based on target temperatures and PCM characteristics.

Cationic boranes for the complexation of fluoride ions in water below the 4 ppm maximum contaminant level.

PubMed

Kim, Youngmin; Gabbaï, François P

2009-03-11

In search of a molecular receptor that could bind fluoride ions in water below the maximum contaminant level of 4 ppm set by the Environmental Protection Agency (EPA), we have investigated the water stability and fluoride binding properties of a series of phosphonium boranes of general formula [p-(Mes(2)B)C(6)H(4)(PPh(2)R)](+) with R = Me ([1](+)), Et ([2](+)), n-Pr ([3](+)), and Ph ([4](+)). These phosphonium boranes are water stable and react reversibly with water to form the corresponding zwitterionic hydroxide complexes of general formula p-(Mes(2)(HO)B)C(6)H(4)(PPh(2)R). They also react with fluoride ions to form the corresponding zwitterionic fluoride complexes of general formula p-(Mes(2)(F)B)C(6)H(4)(PPh(2)R). Spectrophotometric acid-base titrations carried out in H(2)O/MeOH (9:1 vol.) afford pK(R+) values of 7.3(+/-0.07) for [1](+), 6.92(+/-0.1) for [2](+), 6.59(+/-0.08) for [3](+), and 6.08(+/-0.09) for [4](+), thereby indicating that the Lewis acidity of the cationic boranes increases in following order: [1](+) < [2](+) < [3](+) < [4](+). In agreement with this observation, fluoride titration experiments in H(2)O/MeOH (9:1 vol.) show that the fluoride binding constants (K = 840(+/-50) M(-1) for [1](+), 2500(+/-200) M(-1) for [2](+), 4000(+/-300) M(-1) for [3](+), and 10 500(+/-1000) M(-1) for [4](+)) increase in the same order. These results show that the Lewis acidity of the cationic boranes increases with their hydrophobicity. The resulting Lewis acidity increase is substantial and exceeds 1 order of magnitude on going from [1](+) to [4](+). In turn, [4](+) is sufficiently fluorophilic to bind fluoride ions below the EPA contaminant level in pure water. These results indicate that phosphonium boranes related to [4](+) could be used as molecular recognition units in chemosensors for drinking water analysis.

pH-Dependent two novel heteronuclear Cu(II)/Sr(II) coordination polymers constructed from 1,3,5-benzenetricarboxylic acid: Synthesis, crystal structures and properties

NASA Astrophysics Data System (ADS)

Sun, Qiao-Zhen; Yin, Yi-Biao; Pan, Jun-Qiao; Chai, Li-Yuan; Su, Nan; Liu, Hui; Zhao, Yi-Lin; Liu, Xing-Tao

2016-02-01

Two novel heteronuclear coordination polymers, namely, [CuSr2(BTC)2]·10H2O (1) and [Cu2Sr(H4TMA)2]·4H2O (2) (H3BTC = 1,3,5-benzenetricarboxylic acid, H4TMA = 2-hydroxytrimesic acid) were hydrothermally synthesized as pH-dependent products and characterized by elemental analysis (EA), infrared spectroscopy (IR) and single crystal X-ray diffraction. For compound 1, it displays a 3D structure with (2,5,6)-connected net topology. For 2, the H3BTC ligand is oxidized into H4TMA and compound 2 features a 2D layer structure, which is further linked by Cu⋯Cu and Cu⋯O supramolecular interactions into a 3D structure. The results show that the pH plays a crucial role in determining the structure of the compounds. In addition, thermalgravimetric analysis of compounds 1-2 and luminescence property of 1 are also investigated.

Oxidation of bisphenol F (BPF) by manganese dioxide.

PubMed

Lu, Zhijiang; Lin, Kunde; Gan, Jay

2011-10-01

Bisphenol F (BPF), an environmental estrogen, is used as a monomer in plastic industry and its environmental fate and decontamination are emerging concern. This study focused on the kinetics, influencing factors and pathways of its oxidation by MnO(2). At pH 5.5, about 90% of BPF was oxidized in 20 min in a solution containing 100 μM MnO(2) and 4.4 μM BPF. The reaction was pH-dependent, following an order of pH 4.5 > pH 5.5 > pH 8.6 > pH 7.5 > pH 6.5 > pH 9.6. Humic acids inhibited the reaction at low (≤ pH 5.5) and high pH (≥ pH 8.6) at high concentrations. In addition, metal ions and anions also suppressed the reaction, following the order Mn(2+) > Ca(2+) > Mg(2+) > Na(+) and HPO(4)(2-) > Cl(-) > NO(3)(-) ≈ SO(4)(2-), respectively. A total of 5 products were identified, from which a tentative pathway was proposed. Copyright © 2011 Elsevier Ltd. All rights reserved.

Synthesis, Crystal Structure, and Luminescent Properties of Ag(I) Coordination Polymer with Tricarboxylic Acid and Flexible N-donor Ligand

NASA Astrophysics Data System (ADS)

Lu, J. F.; Xu, Y. H.; Li, P. A.; Jin, L. X.; Zhao, C. B.; Guoand, X. H.; Ge, H. G.

2017-12-01

The reaction of AgNO3 with combinations of 1,3-bis(4-pyridyl)propane ( bpp) and 1,3,5-benzenetricarboxylic acid (H3btc) in aqueous alcohol/ammonia at room temperature produces crystals of {[Ag6(H2O)2( bpp)6] · ( btc)2 · 25H2O} n (Ι). Single crystal X-ray diffraction analysis reveals that the complex Ι consists of 1D infinite cationic chains of [Ag( bpp)] n n+ and [Ag(H2O)( bpp)] n n+ which are further linked into the cation layer of [Ag( bpp)] n n+ by Ag···π interactions. The noncoordinated btc 3- serves as template driving surrounding water molecules to aggregate into the anionic water layer. The neighboring anionic water layer and cationic layer were further alternately joined into a 3D sandwich-like framework by hydrogen bonding. In addition, the luminescent properties of Ι were investigated.

Unraveling the multi-functional behavior in a series of Metal Organic Frameworks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sanda, Suresh; Biswas, Soumava; Parshamoni, Srinivasulu

2015-09-15

Three new 2D/3D Metal-Organic Frameworks (MOFs), ([Zn(2,6-ndc)(aldrithiol)]·3(H{sub 2}O)){sub n} (1), ([Co(2,6-ndc)(aldrithiol)(H{sub 2}O){sub 2}]·2(H{sub 2}O)){sub n} (2), ([Cd{sub 2}(2,6-ndc){sub 2}(aldrithiol){sub 2}(H{sub 2}O){sub 2}]·(aldrithiol)·(EtOH)·3(H{sub 2}O)){sub n} (3), (2,6-ndc = 2,6-naphthalene dicarboxylic acid; aldrithiol = 4,4'-dipyridyl disulphide) have been synthesized and structurally characterized. Compounds 1 and 2 have 2D layered architectures with similar framework topology whereas 3 is a 2-fold interwoven three dimensional framework. Sorption studies reveal that compounds 1-3 selectively adsorbs CO{sub 2} over other gases and H{sub 2}O over other solvents. Proton conductivity study of compounds 1 and 2 show highest values of 6.73 x 10{sup -7} S.cm{sup -1}, 1.96 xmore » 10{sup -5} S.cm{sup -1} at 318 K and 95% RH and these values are humidity dependent. Photoluminescent properties of compounds 1 and 3 show metal perturbed (π*–π and π*-n) intra ligand charge transfer transitions. Additionally, Compound 3 also displays reversible adsorption of molecular iodine. - Graphical abstarct: Three new 2D/3D interpenetrated MOFs are synthesized and their multifunctional material properties such as adsorption, proton conduction, iodine adsorption as well as luminscence have been explored. - Highlights: • We report multifunctional material properties in a series MOFs (Compounds 1-3) • All the compounds show selective adsorption of CO{sub 2} over other gases and H{sub 2}O over other solvents. • The proton conduction property studies of all the compounds reveal the humidity dependent conductivity. • Compound 2 shows reversible adsorption of molecular iodine in the framework. • Photoluminescent properties of compounds 1 and 2 show metal perturbed intra ligand charge transfer transitions.« less

Halotolerance and survival kinetics of lactic acid bacteria isolated from jalapeño pepper (Capsicum annuum L.) fermentation.

PubMed

González-Quijano, Génesis Karendash; Dorantes-Alvarez, Lidia; Hernández-Sánchez, Humberto; Jaramillo-Flores, María Eugenia; de Jesús Perea-Flores, María; Vera-Ponce de León, Arturo; Hernández-Rodríguez, César

2014-08-01

The microbiota associated with spontaneous fermentation of vegetables in a saline substrate may represent an important group of bacteria in the food industry. In this work, the lactic acid bacteria (LAB) Weissella cibaria, Lactobacillus plantarum, Lactobacillus paraplantarum, and Leuconostoc citreum were identified by partial 16S rRNA gene sequence analysis. In addition, entophytic bacteria such as Pantoea eucalypti, Pantoea anthophila, Enterobacter cowanii, and Enterobacter asburiae were detected, but they were irrelevant for the fermentation process and were inhibited after 12 h of fermentation when the pH decreased from 6.5 to 4.9. Moreover, 2 species of yeast were isolated and identified as Hanseniaspora pseudoguilliermondii and Kodamaea ohmeri by their partial 26S rRNA gene sequence. The growth of LAB was evaluated at different sodium chloride contents. L. citreum was the most halotolerant species followed by L. plantarum and W. cibaria with a concentration index to obtain a 50% population reduction (IC(50)) of 7.2%, 6.6%, and 5.2%, respectively. Furthermore, the growth of LAB and Escherichia coli O157:H7 was evaluated in the presence of the main phenylpropanoids from chilli peppers such as p-coumaric and ferulic acid. It was determined that LAB can grow in both acids at 4 mM, unlike E. coli O157:H7, whose growth is inhibited in the presence of these acids. © 2014 Institute of Food Technologists®

The effect of Nafion membrane thickness on performance of all tungsten-cobalt heteropoly acid redox flow battery

NASA Astrophysics Data System (ADS)

Liu, Yiyang; Wang, Haining; Xiang, Yan; Lu, Shanfu

2018-07-01

Recently, we have reported a new all tungsto-cobalt heteropoly acid redox flow battery (all H6[CoW12O40] RFB) with high coulombic efficiency. Because of the relatively large ion size and high negative charge, the tungsto-cobalt heteropoly acid anion is difficult to cross Nafion membrane, which makes it possible to employ thinner Nafion membrane in all H6[CoW12O40] RFB. In this study, three types of Nafion membranes with different thickness, namely, N212 (50 μm), N211 (25 μm), and N-17 (home-made, 17 μm) are used as polymer electrolyte to investigate its effects on the performance of all H6[CoW12O40] RFB. The ion permeability increases while the area specific resistanceas decreases as reducing the membrane thickness. As a result, the RFB with N211 membrane exhibits best comprehensive performance, which exhibites the energy efficiency of 88.6% at current density of 0.10 A cm-2 and the power density of 0.56 W cm-2 at 0.60 A cm-2. Moreover, the battery delivers impressive cycling performance of 100 cycles with an average coulombic efficiency of 99.4%, energy efficiency of 80.0%, and capacity retention of 99.98% per cycle at current density of 0.20 A cm-2.

A microporous lanthanum metal-organic framework as a bi-functional chemosensor for the detection of picric acid and Fe(3+) ions.

PubMed

Zhang, Chuanqi; Yan, Yan; Pan, Qinhe; Sun, Libo; He, Hongming; Liu, Yunling; Liang, Zhiqiang; Li, Jiyang

2015-08-07

A microporous lanthanum metal-organic framework [La(TPT)(DMSO)2]·H2O (La-MOF ()), has been synthesized using a rigid unsymmetrical tricarboxylate ligand of p-terphenyl-3,4'',5-tricarboxylic acid (H3TPT). The structure of is constructed by bi-nuclear lanthanum clusters and fully deprotonated TPT(3-) ligands, which can be simplified into a 3,6-connected flu-3,6-C2/c topology with a point symbol of (4(4)·6)2(4·6(2)·8(7)·10(2)). The π-electron rich ligand H3TPT enables to have blue luminescence when excited at 342 nm at ambient temperature. Meanwhile, exhibits the selective detection of picric acid (PA) and Fe(3+) ions in ethanol solution over other nitroaromatic compounds and metal ions. The high quenching efficiency and selectivity of makes it a potential bi-functional chemosensor for both PA and Fe(3+) ions.

Sanitizing radish seeds by simultaneous treatments with gaseous chlorine dioxide, high relative humidity, and mild heat.

PubMed

Bang, Jihyun; Choi, Moonhak; Son, Hyeri; Beuchat, Larry R; Kim, Yoonsook; Kim, Hoikyung; Ryu, Jee-Hoon

2016-11-21

Sanitizing radish seeds intended for edible sprout production was achieved by applying simultaneous treatments with gaseous chlorine dioxide (ClO 2 ), high relative humidity (RH, 100%), and mild heat (55°C). Gaseous ClO 2 was produced from aqueous ClO 2 (0.66ml) by mixing sulfuric acid (5% w/v) with sodium chlorite (10 mg/mL) in a sealed container (1.8L). Greater amounts of gaseous ClO 2 were measured at 23% RH (144ppm after 6h) than at 100% RH (66ppm after 6h); however, the lethal activity of gaseous ClO 2 against naturally occurring mesophilic aerobic bacteria (MAB) on radish seeds was significantly enhanced at 100% RH. For example, when exposed to gaseous ClO 2 at 23% RH, the number of MAB on radish seeds decreased from 3.7logCFU/g to 2.6logCFU/g after 6h. However, when exposed to gaseous ClO 2 at 100% RH for 6h, the MAB population decreased to 0.7logCFU/g after 6h. Gaseous ClO 2 was produced in higher amounts at 55°C than at 25°C, but decreased more rapidly over time at 55°C than at 25°C. The lethal activity of gaseous ClO 2 against MAB on radish seeds was greater at 55°C than at 25°C. When radish seeds were treated with gaseous ClO 2 (peak concentration: 195ppm) at 100% RH and 55°C, MAB were reduced to populations below the detectable level (<-0.7logCFU/g) within 2h without decreasing the seed germination rate (97.7%). The lethality of combined treatments against artificially inoculated Escherichia coli O157:H7 was also evaluated. When exposed to gaseous ClO 2 at 100% RH and 55°C for 6h, the initial number of E. coli O157:H7 (3.5logCFU/g) on radish seeds decreased to below the detection limit (0.7logCFU/g) by direct plating but it was not eliminated from seeds. The germination rate of radish seeds was not significantly (P>0.05) decreased after treatment for 6h. The information reported here will be useful when developing decontamination strategies for producing microbiologically safe radish seed sprouts. Copyright © 2016. Published by Elsevier B.V.

Structure and magnetism of a new hydrogen-bonded layered cobalt(II) network, constructed by the unprecedented carboxylate-phosphinate ligand [O2(C6H5)PCH2CO2]2-.

PubMed

Midollini, Stefano; Orlandini, Annabella; Rosa, Patrick; Sorace, Lorenzo

2005-03-21

By hydrothermal reaction of CoCl2 x 6H2O with K2pcc (H2pcc = phenyl(carboxymethyl) phosphinic acid) at 423 K, a novel hybrid material of formula [Co2(pcc)2 (H2O)2] x H2O has been obtained. The compound, which is the first pcc/metal complex reported, exhibits a polymeric arrangement, where cobalt metal ions, linked together by bridging carboxylate and phosphinate oxygens, form infinite chains of edge-shared CoO6 octahedra. The cobalt chains are in turn linked together through important hydrogen-bonding interactions, which create an infinite 2D architecture. The two crystallographically independent cobalt centers, both displaying distorted octahedral coordination, present different environments as one is surrounded by six ligand oxygens and the other by four ligand oxygens and by two water oxygens. Careful magnetic studies performed by a home-built alternating current susceptometer reveal that the system undergoes an antiferromagnetic transition below 2.0 K leading to a canted structure. Field-dependent studies further indicate the occurrence of a metamagnetic transition at a critical field of 650 +/- 50 G.

Speciation in the Fe(III)-Cl(I)-H2O System at 298.15 K, 313.15 K, and 333.15 K (25 °C, 40 °C, and 60 °C)

NASA Astrophysics Data System (ADS)

Jamett, Nathalie E.; Hernández, Pía C.; Casas, Jesús M.; Taboada, María E.

2018-02-01

This article presents the results on speciation of ferric iron generated by the dissolution of chemical reagent hydromolysite (ferric chloride hexahydrate, FeCl3:6H2O) in water at 298.15 K, 313.15 K, and 333.15 K (25 °C, 40 °C, and 60 °C). Experiments were performed with a thermoregulated system up to the equilibrium point, as manifested by solution pH. Solution samples were analyzed in terms of concentration, pH, and electrical conductivity. Measurements of density and refractive index were obtained at different temperatures and iron concentrations. A decrease of pH was observed with the increase in the amount of dissolved iron, indicating that ferric chloride is a strong electrolyte that reacts readily with water. Experimental results were modeled using the hydrogeochemical code PHREEQC in order to obtain solution speciation. Cations and neutral and anion complexes were simultaneously present in the system at the studied conditions according to model simulations, where dominant species included Cl-, FeCl2+, FeCl2 +, FeOHCl 2 0 , and H+. A decrease in the concentration of Cl- and Fe3+ ions took place with increasing temperature due to the association of Fe-Cl species. Standard equilibrium constants for the formation of FeOHCl 2 0 obtained in this study were log Kf0 = -0.8 ± 0.01 at 298.15 K (25 °C), -0.94 ± 0.02 at 313.15 K (40 °C), and -1.03 ± 0.01 at 333.15 K (60 °C).

Efficacy of slightly acidic electrolyzed water in killing or reducing Escherichia coli O157:H7 on iceberg lettuce and tomatoes under simulated food service operation conditions.

PubMed

Pangloli, Philipus; Hung, Yen-Con

2011-08-01

The objective of this study was to evaluate the efficacy of slightly acidic electrolyzed (SAEO) water in killing or removing Escherichia coli O157:H7 on iceberg lettuce and tomatoes by washing and chilling treatment simulating protocols used in food service kitchens. Whole lettuce leaves and tomatoes were spot-inoculated with 100 μL of a mixture of 5 strains of E. coli O157:H7. Washing lettuce with SAEO water for 15 s reduced the pathogen by 1.4 to 1.6 log CFU/leaf, but the treatments did not completely inactivate the pathogen in the wash solution. Increasing the washing time to 30 s increased the reductions to 1.7 to 2.3 log CFU/leaf. Sequential washing in SAEO water for 15 s and then chilling in SAEO water for 15 min also increased the reductions to 2.0 to 2.4 log CFU/leaf, and no cell survived in chilling solution after treatment. Washing tomatoes with SAEO water for 8 s reduced E. coli O157:H7 by 5.4 to 6.3 log CFU/tomato. The reductions were increased to 6.6 to 7.6 log CFU/tomato by increasing the washing time to 15 s. Results suggested that application of SAEO water to wash and chill lettuce and tomatoes in food service kitchens could minimize cross-contamination and reduce the risk of E. coli O157:H7 present on the produce. SAEO water is equally or slightly better than acidic electrolyzed (AEO) water for inactivation of bacteria on lettuce and tomato surfaces. In addition, SAEO water may have the advantages over AEO water on its stability, no chlorine smell, and low corrosiveness. Therefore, SAEO water may have potential for produce wash to enhance food safety. © 2011 Institute of Food Technologists®

Sterilization of Bacillus pumilus spores using supercritical fluid carbon dioxide containing various modifier solutions.

PubMed

Shieh, Edison; Paszczynski, Andrzej; Wai, Chien M; Lang, Qingyong; Crawford, Ronald L

2009-03-01

Supercritical fluid carbon dioxide (SF-CO(2)) with small amounts of chemical modifier(s) provides a very effective sterilization technique that should be useful for destroying microorganism on heat-sensitive devices such as instruments flown on planetary-bound spacecraft. Under a moderate temperature (50 degrees C) and pressure (100 atm), spores of Bacillus pumilus strains ATCC 7061 and SAFR 032 can be effectively inactivated/eliminated from metal surfaces and small electronic devices in only 45 min using optimized modifier concentrations. Modifiers explored in this study included hydrogen peroxide (H(2)O(2)), tert-butyl hydroperoxide, formic acid, and Triton X-100. During sterilization procedure the modifiers were continuously added to SF-CO(2) in either methanol or water at controlled concentrations. The lowest effective concentrations were established for each modifier. Complete elimination of both types of B. pumilus endospores occurred with an optimal modifier addition of either or 10% methanol containing 12% H(2)O(2) or 12% tert-butyl hydroperoxide in SF-CO(2), or a mixture of 6% H(2)O(2) and 6% tert-butyl hydroperoxide. Using water as the carrier of SF-CO(2) modifier, the complete elimination of spores viability of both B. pumilus strains occurred with an addition of either 3.3% water containing 3% H(2)O(2), or 3.3% water containing 10% methanol and 0.5% formic acid, or 3.3% water containing 10% methanol, 1% formic acid and 2% H(2)O(2).

Intramolecular ferro- and antiferromagnetic interactions in oxo-carboxylate bridged digadolinium(III) complexes.

PubMed

Cañadillas-Delgado, Laura; Fabelo, Oscar; Pasán, Jorge; Delgado, Fernando S; Lloret, Francesc; Julve, Miguel; Ruiz-Pérez, Catalina

2010-08-21

Two new digadolinium(III) complexes with monocarboxylate ligands, [Gd2(pac)6(H2O)4] (1) and [Gd2(tpac)6(H2O)4] (2) (Hpac = pentanoic acid and Htpac = 3-thiopheneacetic acid), have been prepared and their structures determined by X-ray diffraction on single crystals. Their structures consist of neutral and isolated digadolinium(III) units, containing six monocarboxylate ligands and four coordinated water molecules, the bridging skeleton being built by a muO(1):kappa2O(1)O(2) framework. This structural pattern has already been observed in the parent acetate-containing compound [Gd2(ac)6(H2O)4] x 4 H2O (3) whose structure and magnetic properties were reported elsewhere (L. Cañadillas-Delgado, O. Fabelo, J. Cano, J. Pasán, F. S. Delgado, M. Julve, F. Lloret and C. Ruiz-Pérez, CrystEngComm, 2009, 11, 2131). Each gadolinium(III) ion in 1 and 2 is nine-coordinated with seven carboxylate-oxygen atoms from four pac (1)/tpac (2) ligands and two water molecules (1 and 2) building a distorted monocapped square antiprism. The values of the intramolecular gadolinium-gadolinium separation are 4.1215(5) (1), 4.1255(6) (2) and 4.1589(3) A (3) and those of the angle at the oxo-carboxylate bridge (theta) are 113.16(13) (1), 112.5(2) (2) and 115.47(7) degrees (3). Magnetic susceptibility measurements in the temperature range 1.9-300 K reveal the occurrence of a weak intramolecular antiferromagnetic interaction [J = -0.032(1) (1) and -0.012(1) cm(-1) (2), the Hamiltonian being defined as H = -JS(A) x S(B)] in contrast with the intramolecular ferromagnetic coupling which occurs in 3 (J = +0.031(1) cm(-1)). The magneto-structural data of 1-3 show the relevance of the geometrical parameters at the muO(1):kappa2O(1)O(2) bridge on the nature of the magnetic coupling between two gadolinium(III) ions.

Heterogeneous photodegradation of methylene blue with iron and tea or coffee polyphenols in aqueous solutions.

PubMed

Morikawa, Claudio Kendi; Shinohara, Makoto

2016-01-01

Recently, we developed two new Fenton catalysts using iron (Fe) and spent tea leaves or coffee grounds as raw material. In this study, Fe-to-tea or Fe-to-coffee polyphenol complexes were successfully tested as heterogeneous photo-Fenton catalysts. The photodegradation efficiency of methylene blue solutions with Fe-to-polyphenol complexes was higher than that of homogeneous iron salts in the photo-Fenton process. Furthermore, the tested Fe-to-polyphenol complexes could be reused by simply adding H2O2 to the solutions. After three sequential additions of H2O2, the conventional catalysts FeCl2·4H2O and FeCl3 removed only 16.6% and 53.6% of the dye, while the catalysts made using spent coffee grounds and tea leaves removed 94.4% and 96.0% of the dye, respectively. These results showed that the complexes formed between Fe and chlorogenic acid, caffeic acid, gallic acid and catechin, which are the main polyphenols in tea and coffee, can be used to improve the photo-Fenton process.

Control of temperature and aqueous Mg2+/Ca2+ ratio on the (trans-)formation of ikaite

NASA Astrophysics Data System (ADS)

Purgstaller, B.; Dietzel, M.; Baldermann, A.; Mavromatis, V.

2017-11-01

The calcium carbonate hexahydrate mineral ikaite (CaCO3 ṡ 6 H2O) has been documented in aquatic environments at near-freezing temperatures. An increase of the prevailing temperature in the depositional environment, results in the transformation of natural ikaite into less soluble calcium carbonate phases occasionally leaving calcite pseudomorphs in the sediments, which are considered as an indicator for primary cold water temperatures. Detailed understanding on the physicochemical parameters controlling ikaite (trans-)formation however, such as temperature and reactive solution chemical composition, are still under debate. In order to study the formation of ikaite, we conducted precipitation experiments under controlled physicochemical conditions (pH = 8.3 ± 0.1; T = 6, 12, and 18 ± 0.1 °C) at defined aqueous molar Mg/Ca ratios. The transformation of ikaite into anhydrous calcium carbonate polymorphs was investigated in solution and at air exposure. The obtained results reveal the formation of ikaite at temperatures up to 12 °C, whereas Mg-rich amorphous calcium carbonate precipitated at 18 °C. In contact with the reactive solution ikaite transformed into aragonite at aqueous molar Mg2+/Ca2+ ratios of ≥14. In contrast, ikaite separated from the Mg-rich solution and exposed to air transformed in all cases into calcite/vaterite. The herein obtained temperature limit of ≤12 for ikaite formation is significantly higher than formerly expected and most probably caused by (i) the high saturation degree of the solution with respect to ikaite and (ii) the slow dehydration of the aqueous Ca2+ ion at low temperatures. This result questions the suitability of calcite pseudomorphs (i.e. glendonites) as a proxy for near-freezing temperatures. Moreover, our findings show that the CaCO3 polymorph formed from ikaite is strongly controlled by the physicochemical conditions, such as aqueous molar Mg2+/Ca2+ ratio of the reactive fluid and H2O availability throughout the transformation process.

Synthesis of feather-like CeO2 microstructures and enzymatic electrochemical catalysis for trichloroacetic acid

NASA Astrophysics Data System (ADS)

Xiao, Xin; Zhang, Dong En; Zhang, Fan; Gong, Jun Yan; Zhang, Xiao Bo; Wang, Yi Hui; Ma, Juan Juan; Tong, Zhi Wei

Novel feather-like CeO2 microstructures were achieved by a thermal decomposition approach of Ce(OH)CO3 precursor. The Ce(OH)CO3 was obtained from a solvothermal method employing Ce(NO3)3.6H2O with C6H12N4 and C16H33(CH3)3NBr (CTAB) at 190∘C in a water-PEG-200 mixed solution. The feather-like CeO2 dendrite was obtained by thermal conversion of the feather-like Ce(OH)CO3 at 650∘C in air. A reasonable growth mechanism was proposed with the soft-template effect of PEG-200. The electrochemical behavior and enzyme activity of myoglobin (Mb) immobilized on CeO2-Nafion modified glassy carbon electrode (GCE) are demonstrated by cyclic voltammetric measurements. The results indicate that CeO2 can obviously promote the direct electron transfer between the Mb redox centers and the electrode. The Mb on CeO2-Nafion behaves as an elegant performance on the electrochemical reduction of trichloroacetic acid (TCA) from 0.32μM to 2.28μM. The detection limit is estimated to be 0.08μM.

Six uranyl-organic frameworks with naphthalene-dicarboxylic acid and bipyridyl-based spacers: syntheses, structures, and properties.

PubMed

Xu, Wei; Ren, Ya-Nan; Xie, Miao; Zhou, Lin-Xia; Zheng, Yue-Qing

2018-03-28

A new series of uranium coordination polymers have been hydrothermally synthesized by using 1,4-naphthalene dicarboxylic acid (H 2 NDC), namely, (H 3 O) 2 [(UO 2 ) 2 (NDC) 3 ]·H 2 O (1), (H 2 -bpp)[(UO 2 ) 2 (NDC) 3 ]·EtOH·5H 2 O (2), (H 2 -bpe) 2/2 [(UO 2 ) 2 (NDC) 3 ]·EtOH (3), (H 2 -bpp)[(UO 2 ) 2 (NDC) 3 ]·5H 2 O (4), (H 2 -bpp)[(UO 2 )(HNDC)(NDC)] 2 ·2H 2 O (5), and (H 2 -bpy)[(UO 2 )(NDC) 2 ] (6) [bpp = 1,3-di(4-pyridyl) propane, bpe = 4,4'-vinylenedipyridine, bpy = 4,4'-bipyridine]. Single-crystal X-ray diffraction demonstrates that complex 1 represents the uranyl-organic polycatenated framework derived from a simple two-dimensional honeycomb grid network structure via a H 2 NDC linker. Complexes 2-4 contain the dinuclear motifs of the two UO 7 pentagonal and one UO 8 hexagonal bipyramids which are linked by NDC 2- anions creating a (UO 2 ) 4 (NDC) 2 unit, and further extend to a 2D layer through NDC 2- anions. Complex 5 displays a 1D zigzag double chain structure, in which the carboxylate groups of the NDC 2- anions adopt a chelate mode and further extends to a 2D framework via hydrogen bonds. The 1D structure of complex 6 is similar to the zigzag chain of complex 5. In addition, powder X-ray diffraction, elemental analysis, IR, thermal stability and luminescence properties of all complexes have also been investigated in this paper. The photocatalytic properties of the six complexes for the degradation of tetracycline hydrochloride (TC) under UV irradiation have been examined. Moreover, density functional theory (DFT) calculations were carried out to explore the electronic structural and bonding properties of the uranyl complexes 1-6.

Two Co(II) compound constructed by phthalic acid and 3-Cl-phthalic acid: Synthesis, structure, and magnetic properties

NASA Astrophysics Data System (ADS)

Meng, Jun-Rong; Yao, Peng-Fei; Cui, Lian-Sheng; Gan, Yong-Le; Li, Hai-Ye; Liu, Han-Fu; Huang, Fu-Ping

2018-03-01

In this paper, we obtained two novel 2D layered cobalt coordination polymers, namely [(Co(o-BDC)]n (1) and (Co(3-Cl-o-BDC)]n (2), through solvothermal method with acetone as solvent based on phthalic acid (o-H2BDC) and 3-chloro-phthalic acid (3-Cl-o-H2BDC) respectively. Due to the steric hindrance effect of chloric substituent, the two ligands revealed different coordination modes. And cobalt centers of 1 and 2 showed CoO6 octahedral and CoO4 tetrahedral configurations respectively. As a result, 1 and 2 revealed different layered constructions: a 5-connected topology with 48.62 Schläfli symbol for 1, and a 4-connected topology with 44.62 Schläfli symbol for 2, respectively. Besides, Compound 1 and 2 reveal ferromagnetic and antiferromagnetic behaviors, respectively.

Impact of ambient gases on the mechanism of [Cs8Nb6O19]-promoted nerve-agent decomposition.

PubMed

Kaledin, Alexey L; Driscoll, Darren M; Troya, Diego; Collins-Wildman, Daniel L; Hill, Craig L; Morris, John R; Musaev, Djamaladdin G

2018-02-28

The impact of ambient gas molecules (X), NO 2 , CO 2 and SO 2 on the structure, stability and decontamination activity of Cs 8 Nb 6 O 19 polyoxometalate was studied computationally and experimentally. It was found that Cs 8 Nb 6 O 19 absorbs these molecules more strongly than it adsorbs water and Sarin (GB) and that these interactions hinder nerve agent decontamination. The impacts of diamagnetic CO 2 and SO 2 molecules on polyoxoniobate Cs 8 Nb 6 O 19 were fundamentally different from that of NO 2 radical. At ambient temperatures, weak coordination of the first NO 2 radical to Cs 8 Nb 6 O 19 conferred partial radical character on the polyoxoniobate and promoted stronger coordination of the second NO 2 adsorbent to form a stable diamagnetic Cs 8 Nb 6 O 19 /(NO 2 ) 2 species. Moreover, at low temperatures, NO 2 radicals formed stable dinitrogen tetraoxide (N 2 O 4 ) that weakly interacted with Cs 8 Nb 6 O 19 . It was found that both in the absence and presence of ambient gas molecules, GB decontamination by the Cs 8 Nb 6 O 19 species proceeds via general base hydrolysis involving: (a) the adsorption of water and the nerve agent on Cs 8 Nb 6 O 19 /(X), (b) concerted hydrolysis of a water molecule on a basic oxygen atom of the polyoxoniobate and nucleophilic addition of the nascent OH group to the phosphorus center of Sarin, and (c) rapid reorganization of the formed pentacoordinated-phosphorus intermediate, followed by dissociation of either HF or isopropanol and formation of POM-bound isopropyl methyl phosphonic acid (i-MPA) or methyl phosphonofluoridic acid (MPFA), respectively. The presence of the ambient gas molecules increases the energy of the intermediate stationary points relative to the asymptote of the reactants and slightly increases the hydrolysis barrier. These changes closely correlate with the Cs 8 Nb 6 O 19 -X complexation energy. The most energetically stable intermediates of the GB hydrolysis and decontamination reaction were found to be Cs 8 Nb 6 O 19 /X-MPFA-(i-POH) and Cs 8 Nb 6 O 19 /X-(i-MPA)-HF both in the absence and presence of ambient gas molecules. The high stability of these intermediates is due to, in part, the strong hydrogen bonding between the adsorbates and the protonated [Cs 8 Nb 6 O 19 /X/H] + -core. Desorption of HF or/and (i-POH) and regeneration of the catalyst required deprotonation of the [Cs 8 Nb 6 O 19 /X/H] + -core and protonation of the phosphonic acids i-MPA and MPFA. This catalyst regeneration is shown to be a highly endothermic process, which is the rate-limiting step of the GB hydrolysis and decontamination reaction both in the absence and presence of ambient gas molecules.

Benzamide–picric acid (1/1)

PubMed Central

Sivaramkumar, M. S.; Velmurugan, R.; Sekar, M.; Ramesh, P.; Ponnuswamy, M. N.

2010-01-01

In the title compound, C7H7NO·C6H3N3O7, one of the nitro groups of the picric acid mol­ecule lies in the plane of the attached benzene ring [dihedral angle = 1.4 (1)°] while the other two are twisted away by 9.9 (1) and 30.3 (1)°. In the benzamide mol­ecule, the amide group is almost coplanar with the benzene ring [dihedral angle = 4.4 (1)°]. An intra­molecular O—H⋯O hydrogen bond generates an S6 ring motif. In the crystal, mol­ecules are linked into a ribbon-like structure along the b axis by O—H⋯O and N—H⋯O inter­molecular hydrogen bonds. In addition, C—H⋯O hydrogen bonds and short O⋯O contacts [2.828 (2) Å] are observed. PMID:21588027

Hydrothermal preparation of ZnO-reduced graphene oxide hybrid with high performance in photocatalytic degradation

NASA Astrophysics Data System (ADS)

Zhou, Xun; Shi, Tiejun; Zhou, Haiou

2012-06-01

Hydrothermal method was utilized to prepare reduced graphene oxide (RGO) and fabricate ZnO-RGO hybrid (ZnO-RGO) with zinc nitrate hexahydrate and graphene oxide (GO) as raw materials under pH value of 11 adjusted by ammonia water. During the process of reduction of GO, hydrothermal condition with ammonia provided thermal and chemical factors to synthesize RGO. The retained functional groups on RGO planes played an important role in anchoring ZnO to RGO, which was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning and transmission electron microscopy and photoluminescence spectra. The various mass ratios of zinc nitrate hexahydrate to GO used to prepare ZnO-RGO impacted significantly on the morphology of ZnO nanostructures such as nanoparticles and nanorods. And, the RGO sheets wrapped ZnO nanoparticles and nanorods very tightly. After the emission of photo electrons from ZnO, RGO in ZnO-RGO can effectively transfer the photo electrons to exhibit a high performance and reproducibility in photocatalytic degradation toward methylene blue (MB) absorbed on the surface of RGO through π-π conjugation.

Mononitration of durene

NASA Technical Reports Server (NTRS)

Hanna, S. B.; Hunziker, E.; Saito, T.; Zollinger, H.

1984-01-01

Reaction conditions under which the nitration of durene give predominantly, and in high yield, mononitrodurene (I), rather than dinitrodurene were found. The nitrating agent was No2+RF6-. Nitration with nitrosulfuric acid also gave mononitrodurene; however, byproducts such as 2.3.5.6-Me4C6HCH2C6H2Me3-2,4,5, were also formed. The NO2 PF6- gave an intermediate additional compound with durene. The reaction carried out with 3.6-dideuterodurene in D2O shows no isotope effect.

O2-dependent Aliphatic Carbon-carbon Bond Cleavage Reactivity in a Ni(II) Enolate Complex Having a Hydrogen Bond Donor Microenvironment; Comparison with a Hydrophobic Analog

PubMed Central

Grubel, Katarzyna; Fuller, Amy L.; Chambers, Bonnie M.; Arif, Atta M.; Berreau, Lisa M.

2010-01-01

A mononuclear Ni(II) complex having an acireductone type ligand, and supported by the bnpapa (N,N-bis((6-neopentylamino-2-pyridyl)methyl-N-((2-pyridyl)methyl)amine ligand, [(bnpapa)Ni(PhC(O)C(OH)C(O)Ph)]ClO4 (14), has been prepared and characterized by elemental analysis, 1H NMR, FTIR, and UV-vis. To gain insight into the 1H NMR features of 14, the air stable analog complexes [(bnpapa)Ni(CH3C(O)CHC(O)CH3)]ClO4 (16) and [(bnpapa)Ni(ONHC(O)CH3)]ClO4 (17) were prepared and characterized by X-ray crystallography, 1H NMR, FTIR, UV-vis, mass spectrometry, and solution conductivity measurements. Compounds 16 and 17 are 1:1 electrolyte species in CH3CN. 1H and 2H NMR studies of 14, 16, and 17 and deuterated analogs revealed that the complexes having six-membered chelate rings for the exogenous ligand (14 and 16) do not have a plane of symmetry within the solvated cation and thus exhibit more complicated 1H NMR spectra. Compound 17, as well as other simple Ni(II) complexes of the bnpapa ligand (e.g. [(bnpapa)Ni(ClO4)(CH3CN)]ClO4 (18) and [(bnpapaNi)2(μ-Cl)2](ClO4)2 (19)), exhibit 1H NMR spectra consistent with the presence of a plane of symmetry within the cation. Treatment of [(bnpapa)Ni(PhC(O)C(OH)C(O)Ph)]ClO4 (14) with O2 results in aliphatic carbon-carbon bond cleavage within the acireductone-type ligand and the formation of [(bnpapa)Ni(O2CPh)]ClO4 (9), benzoic acid, benzil, and CO. Use of 18O2 in the reaction gives high levels of incorporation (>80%) of one labeled oxygen atom into 9 and benzoic acid. The product mixture and level of 18O incorporation in this reaction is different than that exhibited by the analog supported the hydrophobic 6-Ph2TPA ligand, [(6-Ph2TPA)Ni(PhC(O)C(OH)C(O)Ph)]ClO4 (2). We propose that this difference is due to variations in the reactivity of bnpapa- and 6-Ph2TPA-ligated Ni(II) complexes with triketone and/or peroxide species produced in the reaction pathway. PMID:20039645

Evidence of calcium carbonates in coastal (Talos Dome and Ross Sea area) East Antarctica snow and firn: Environmental and climatic implications

NASA Astrophysics Data System (ADS)

Sala, M.; Delmonte, B.; Frezzotti, M.; Proposito, M.; Scarchilli, C.; Maggi, V.; Artioli, G.; Dapiaggi, M.; Marino, F.; Ricci, P. C.; De Giudici, G.

2008-07-01

Micrometre-sized aeolian dust particles stored in Antarctic firn and ice layers are a useful tool for reconstructing climate and environmental changes in the past. The mineral content, particle concentration and chemical composition of modern dust in firn cores from the peripherycal dome (Talos Dome) and coastal area of East Antarctica (Ross Sea sector) were investigated. During analyses there was a considerable decrease in microparticle concentrations within a few hours of ice sample melting, accompanied by a systematic increase in the concentration of calcium ions (Ca 2+) in solution. Based on mineralogical phase analyses, which reveal the presence of anhydrous and hydrous calcium carbonates such as calcite (CaCO 3), monohydrocalcite (CaCO 3·H 2O) and ikaite (CaCO 3·6H 2O, hexahydrate calcium carbonate), the observed variations in concentrations are ascribed to the partial dissolution of the carbonate content of samples. Soluble carbonate compounds are thus primary aerosols included into the samples along with insoluble aluminosilicate minerals. We hypothesize hydrous carbonates may derive from the sea ice surface, where ikaite typically forms at the early stages of sea ice formation. Back trajectory calculations show that favourable events for air mass advection from the sea ice surface to Talos Dome are rare but likely to occur.

A novel ruthenium(II)-cobaloxime supramolecular complex for photocatalytic H2 evolution: Synthesis, characterisation, and mechanistic studies

PubMed Central

Cropek, Donald M.; Metz, Anja; Müller, Astrid M.; Gray, Harry B.; Horne, Toyketa; Horton, Dorothy C.; Poluektov, Oleg; Tiede, David M.; Weber, Ralph T.; Jarrett, William L.; Phillips, Joshua D.

2012-01-01

We report the synthesis and characterization of novel mixed-metal binuclear ruthenium(II)-cobalt(II) photocatalysts for hydrogen evolution in acidic acetonitrile. First, 2-(2′-pyridyl)benzothiazole (pbt), 1, was reacted with RuCl3·xH2O to produce [Ru(pbt)2Cl2] ·0.25CH3COCH3, 2, which was then reacted with 1,10-phenanthroline-5,6-dione (phendione), 3 in order to produce [Ru(pbt)2(phendione)](PF6)2·4H2O, 4. Compound 4 was then reacted with 4-pyridinecarboxaldehyde in order to produce [Ru(pbt)2(L-pyr)](PF6)2·9.5H2O, 5 (where L-pyr = (4-pyridine)oxazolo[4,5-f]phenanthroline). Compound 5 was then reacted with [Co(dmgBF2)2(H2O)2] (where dmgBF2 = difluorboryldimethylglyoximate) in order to produce the mixed-metal binuclear complex, [Ru(pbt)2(L-pyr)Co(dmgBF2)2(H2O)](PF6)2·11H2O·1.5CH3COCH3, 6. [Ru(Me2bpy)2(L-pyr)Co(dmgBF2)2(OH2)](PF6)2, 7 (where Me2bpy = 1,10-phenanthroline, 4,4′-dimethyl-2,2′-bipyridine) and [Ru(phen)2(L-pyr)Co(dmgBF2)2(OH2)](PF6)2, 8 were also synthesised. All complexes were characterized by elemental analysis, UV-visible absorption, 11B, 19F, and 59Co NMR, ESR spectroscopy, and cyclic voltammetry, where appropriate. Photocatalytic studies carried out in acidified acetonitrile demonstrated constant hydrogen generation longer than a 42 hour period as detected by gas chromatography. Time resolved spectroscopic measurements were performed on compound 6, which proved an intramolecular electron transfer from an excited Ru(II) metal centre to the Co(II) metal centre via the bridging L-pyr ligand. This resulted in the formation of a cobalt(I)-containing species that is essential for the production of H2 gas in the presence of H+ ions. A proposed mechanism for the generation of hydrogen is presented. PMID:23001132

Chemical quality and oxidative stability of extra virgin olive oils from San Juan province (Argentina).

PubMed

Ceci, Liliana N; Mattar, Susana B; Carelli, Amalia A

2017-10-01

This study provides information about the chemical quality (quality indices, fatty acid profile, total polyphenols (PPs), tocopherols and pigments) and oxidative stability index (OSI) of virgin olive oils of Arbequina, Changlot Real and Coratina cultivars (San Juan province, Argentina). The influence of the cultivar and the effect of earlier harvest dates on the yields (OY), quality and OSI of the oils were also evaluated. All the oils were classified as extra virgin. The OY (L/100kg) averaged: Arbequina=13.2, Changlot Real=21.3, Coratina=18.3. The oleic acid (O) percentage, oleic to linoleic plus linolenic ratio [O/(L+Ln)], PPs and OSI were highly dependent on cultivar (Arbequina

Phosphotungstic acid binding in situ to K4Nb6O17 for the effective adsorption-photocatalytic removal of tetracycline

NASA Astrophysics Data System (ADS)

Gu, Huimin; Lang, Junyu; Ma, Yuli; Gu, Huayu; Song, Yanyong; Chai, Zhanli; Li, Guangshe; Wang, Xiaojing

2018-05-01

In this investigation, phosphotungstic acid (H3PW12O40) was successfully self-assembly implanted into the interspace of K4Nb6O17 nanosheet via an impregnation method to form an adsorption-photocatalytic composite, in which n-type semiconductor K4Nb6O17 was selected as photo-electron emitter and H3PW12O40 was particularly used as an electronic transmitter. By characterizing with X-ray diffraction (XRD), transmission (TEM), scan electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and FT-IR spectrum (FT-IR), it confirmed that H3PW12O40 (HPW) was converted to the insoluble tiny particles of K3PW12O40 (KPW) with the remained primary Keggin group via an ion-exchanged H+ of HPW with K+ in K4Nb6O17 in the implanted process and was firmly bound to the surface of K4Nb6O17 to form well sandwich structure. UV-vis diffuse reflectance spectroscopy revealed that the band gap of K4Nb6O17-K3PW12O40 have a slight red shift compared with the single K4Nb6O17. Its adsorption-photocatalytic properties were evaluated with the removal of tetracycline as model reaction. Compared with pure K4Nb6O17, tetracycline removal rate can be significantly improved for the as-prepared sandwich. Importantly, the removal could still maintain 70% after five reuses in recycle tests at an acidic solution, inferring a good stability which was mainly ascribed to the formation of water-insoluble K3PW12O40. The separation and transfer process of photogenerated electrons were investigated by surface photovoltage spectroscopy (SPV). It proposed that the KPW anchored firmly on the interlayers of K4Nb6O17 through a O-K-O bridge plays a significantly role in promoting the separation of the photogenerated carriers and preventing the leakage and agglomeration of HPW. The present results showed that the strategy of the phosphotungstic acid binding in situ to K4Nb6O17 was favorable to promote the hetero-photocatalytic efficiency as well as reusability. [Figure not available: see fulltext.

Ion-Ice Astrochemistry: Barrierless Low-Energy Deposition Pathways to HCOOH, CH3OH, and CO2 on Icy Grain Mantles from Precursor Cations

NASA Technical Reports Server (NTRS)

Woon, David E.

2011-01-01

A new family of very favorable reaction pathways is explored involving the deposition of ions on icy grain mantles with very low energies. Quantum chemical cluster calculations at the MP2/6-31+G** level in 4H2O clusters and at the B3LYP/6-31+G** level in 17H2O clusters indicate that HCO+ and CH3 + are able to react spontaneously with one of the water molecules in the cluster to form protonated formic acid (HCOOH2 +) and protonated methanol (CH3OH2 +), respectively. It is furthermore found that these initial adducts spontaneously transfer their excess protons to the cluster to form neutral formic acid and methanol, plus solvated hydronium, H3O+. In the final case, if a CO molecule is bound to the surface of the cluster, OH+ may react with it to form protonated carbon dioxide (HCO2 +), which then loses its proton to yield CO2 and H3O+. In the present model, all of these processes were found to occur with no barriers. Discussion includes the analogous gas phase processes, which have been considered in previous studies, as well as the competitive abstraction pathway for HCO(+) + H2O.

Effects of strong hydrogen bonds and weak intermolecular interactions on supramolecular assemblies of 4-fluorobenzylamine

NASA Astrophysics Data System (ADS)

Wang, Shi; Ding, Xue-Hua; Li, Yong-Hua; Huang, Wei

2015-07-01

A series of supramolecular salts have been obtained by the self-assembly of 4-fluorobenzylamine and halide ions or metal chloride with 18-crown-6 as the host in the hydrochloric acid medium, i.e. (C7H9FN)+ṡX- (X = Cl-, 1; Br-, 2), [(C7H9FN)2ṡ(18-crown-6)2]2+ṡ(MCl4)2- (M = Mn, 3; Co, 5; Zn, 7; Cd, 8), [(C7H9FN)ṡ(18-crown-6)]+ṡ(FeCl4)- (4) and [(C7H9FN)ṡ(18-crown-6)]+ṡ1/2(CuCl4)2- (6). Structural analyses indicate that 1-2 crystallize in the triclinic space group P-1, 4 in orthorhombic space group Pnma and 3, 5, 6-8 in the monoclinic space group P21/c or C2/c. In these compounds, extensive intermolecular interactions have been utilized for the self-assembly of diverse supramolecular architectures, ranging from strong N-H⋯X (X = O, Cl, Br) hydrogen bonds to weak C-H⋯Y (Y = F, Cl, π) interactions. N-H⋯Cl/Br hydrogen bonds offer the major driving force in the crystal packing of salts 1-2 while N-H⋯O hydrogen bonds are found in salts 3-8.

A Reflectron Time-of-Flight Mass Spectrometric Study on the Degradation Pathways of Glycine on Mars in the Presence of Perchlorates and Ionizing Radiation

NASA Astrophysics Data System (ADS)

Góbi, Sándor; Förstel, Marko; Maksyutenko, Pavlo; Kaiser, Ralf I.

2017-02-01

The absence of abundant organics on the Martian surface is a much discussed observation. So far, no explanation is completely satisfactory. In this study we aim for a deeper understanding of the degradation processes of organics in the presence of perchlorates that can take place on the Martian surface. Our primary goal is to study the radiation-induced decomposition process of glycine (H2NCH2COOH) in the absence and presence of an oxidizer relevant to the Martian surface—perchlorate anions ({{{ClO}}4}-). Glycine and various samples of glycine-1-13C (+H3NC{{{{H}}}2}13COO-)-magnesium perchlorate hexahydrate (Mg(ClO4)2 · 6H2O) were exposed to energetic electrons mimicking secondary electrons originating from the interaction of galactic cosmic rays (GCRs) with the Martian regolith. Using isotope-labeled and deuterated pure glycine samples such as glycine-1-13C, glycine-d5 (+D3NCD2COO-), glycine-N,N,N-d3 (+D3NCH2COO-), and glycine-2,2-d2 (+H3NCD2COO-), we can conclude that decarboxylation (carbon dioxide loss) of the glycine molecule is exclusively the first decay step during irradiation regardless of whether perchlorate anions are present or not. In pure glycine samples, the decarboxylation co-product methylamine (CH3NH2) and its radiolytic decay product ammonia could both be detected explicitly for the first time. In the presence of perchlorates, (partial) oxidation of the glycine decarboxylation product CH3NH2 may occur. Because the decarboxylation is an equilibrium reaction and the CH3NH2 is effectively removed from the system by this oxidation, glycine cannot be recycled. Therefore the depletion of the CH3NH2 facilitates the process, resulting in an overall 10-fold increase in the formation rate of carbon dioxide and its elevated concentrations in the perchlorate-containing irradiated samples.

Depth treatment of coal-chemical engineering wastewater by a cost-effective sequential heterogeneous Fenton and biodegradation process.

PubMed

Fang, Yili; Yin, Weizhao; Jiang, Yanbin; Ge, Hengjun; Li, Ping; Wu, Jinhua

2018-05-01

In this study, a sequential Fe 0 /H 2 O 2 reaction and biological process was employed as a low-cost depth treatment method to remove recalcitrant compounds from coal-chemical engineering wastewater after regular biological treatment. First of all, a chemical oxygen demand (COD) and color removal efficiency of 66 and 63% was achieved at initial pH of 6.8, 25 mmol L -1 of H 2 O 2 , and 2 g L -1 of Fe 0 in the Fe 0 /H 2 O 2 reaction. According to the gas chromatography-mass spectrometer (GC-MS) and gas chromatography-flame ionization detector (GC-FID) analysis, the recalcitrant compounds were effectively decomposed into short-chain organic acids such as acetic, propionic, and butyric acids. Although these acids were resistant to the Fe 0 /H 2 O 2 reaction, they were effectively eliminated in the sequential air lift reactor (ALR) at a hydraulic retention time (HRT) of 2 h, resulting in a further decrease of COD and color from 120 to 51 mg L -1 and from 70 to 38 times, respectively. A low operational cost of 0.35 $ m -3 was achieved because pH adjustment and iron-containing sludge disposal could be avoided since a total COD and color removal efficiency of 85 and 79% could be achieved at an original pH of 6.8 by the above sequential process with a ferric ion concentration below 0.8 mg L -1 after the Fe 0 /H 2 O 2 reaction. It indicated that the above sequential process is a promising and cost-effective method for the depth treatment of coal-chemical engineering wastewaters to satisfy discharge requirements.

Phase Transitions in MIITiF6 · 6H2O (M = Cd, Zn, Co): An EPR Study

NASA Astrophysics Data System (ADS)

Jayaram, Geetha

1994-05-01

Paramagnetic Mn2+ ions have been incorporated into CdTiF6 · 6H2O, ZnTiF6 · 6H2O and CoTiF6 · 6H2O single crystals, and EPR spectra have been utilized to investigate the structural phase transitions in these crystals. They are first order in nature with a marked hysteresis in the case of CoTiF6 · 6H2O and are attributed to hindering of rotation of the [M(H2O)6] as well as (TiF6) groups.

Synthesis, X-ray crystal structures and catecholase activity investigation of new chalcone ligands

NASA Astrophysics Data System (ADS)

Thabti, Salima; Djedouani, Amel; Rahmouni, Samra; Touzani, Rachid; Bendaas, Abderrahmen; Mousser, Hénia; Mousser, Abdelhamid

2015-12-01

The reaction of dehydroacetic acid DHA carboxaldehyde and RCHO derivatives (R = quinoleine-8-; indole-3-; pyrrol-2- and 4-(dimethylamino)phenyl - afforded four new chalcone ligands (4-hydroxy-6-methyl-3-[(2E)-3-quinolin-8-ylprop-2-enoyl]-2H-pyran-2-one) L1, (4-hydroxy-3-[(2E)-3-(1H-indol-3-yl)prop-2-enoyl]-6-methyl-2H-pyran-2-one) L2, (4-hydroxy-6-methyl-3-[(2E)-3-(1H-pyrrol-2-yl)prop-2-enoyl]-2H-pyran-2-one) L3, and (3-{(2E)-3-[4-(dimethylamino)phenyl]prop-2-enoyl}-4-hydroxy-6-methyl-2H-pyran-2-one) L4. L3 and L4 were characterized by X-ray crystallography. Molecules crystallize with four and two molecules in the asymmetric unit, respectively and adopt an E conformation about the Cdbnd C bond. Both structures are stabilized by an extended network O-H … O. Furthermore, N-H … O and C-H … O hydrogen bonds are observed in L3 and L4 structures, respectively. The in situ generated copper (II) complexes of the four compounds L1, L2, L3 and L4 were examined for their catalytic activities and were found to catalyze the oxidation reaction of catechol to o-quinone under atmospheric dioxygen. The rates of this oxidation depend on three parameters: ligand, ion salts and solvent nature and the combination L2[Cu (CH3COO)2] leads to the faster catalytic process.

Comparison of different advanced oxidation processes for the degradation of two fluoroquinolone antibiotics in aqueous solutions.

PubMed

Bobu, Maria; Yediler, Ayfer; Siminiceanu, Ilie; Zhang, Feifang; Schulte-Hostede, Sigurd

2013-01-01

In this study a comparative assessment using various advanced oxidation processes (UV/H(2)O(2), UV/H(2)O(2)/Fe(II), O(3), O(3)/UV, O(3)/UV/H(2)O(2) and O(3)/UV/H(2)O(2)/Fe(II)) was attempted to degrade efficiently two fluoroquinolone drugs ENR [enrofloxacin (1-Cyclopropyl-7-(4-ethyl-1-piperazinyl)-6-fluoro-1,4-dihydro-4-oxo-3-quinolonecarboxylic acid)] and CIP [ciprofloxacin (1-cyclopropyl-6-fluoro-4-oxo-7-(piperazin-1-yl)-quinoline-3-carboxylic acid)] in aqueous solutions at a concentrations of 0.15 mM for each drug. The efficiency of the applied oxidation processes (AOPs) has been estimated by the conversion of the original substrate (X(ENR) and X(CIP)) and the reduction of chemical oxygen demand (COD), total organic carbon (TOC). Special emphasis was laid on the effect of varying reaction pH as well as of the applied oxidant doses on the observed reaction kinetics for each advanced oxidation processes. High degradation efficiencies, particularly in terms of rates of TOC and COD abatement, were obtained for photo-Fenton assisted ozonation [O(3)/UV/H(2)O(2)/Fe(II)], compared to other advanced oxidation processes. At pH 3 and 25°C best results for the degradation of both investigated drugs were achieved when 10 mM H(2)O(2), 0.5 mM Fe(II) and an initial dose of 8.5 mg L(-1) ozone were applied. In addition, the evolution of toxicity of the reaction mixtures for different AOPs has been studied by the bioluminescence test (LUMIStox 300).

Effect of evaporation and freezing on the salt paragenesis and habitability of brines at the Phoenix landing site

NASA Astrophysics Data System (ADS)

Elsenousy, Amira; Hanley, Jennifer; Chevrier, Vincent F.

2015-07-01

The WCL (Wet Chemistry Lab) instrument on board the Phoenix Lander identified the soluble ionic composition of the soil at the landing site. However, few studies have been conducted to understand the parent salts of these soluble ions. Here we studied the possible salt assemblages at the Phoenix landing site using two different thermodynamic models: FREZCHEM and Geochemist's Workbench (GWB). Two precipitation pathways were used: evaporation (T > 0 °C using both FREZCHEM and GWB) and freezing (T < 0 °C using only FREZCHEM). Through applying three different models of initial ionic concentrations (from sulfate to chlorate/perchlorate dominated), we calculated the resulting precipitated minerals. The results-through both freezing and evaporation-showed some common minerals that precipitated regardless of the ionic initial concentration. These ubiquitous minerals are magnesium chlorate hexahydrate Mg(ClO3)2ṡ6H2O, potassium perchlorate (KClO4) and gypsum (CaSO4ṡ2H2O). Other minerals evidence specific precipitation pathway. Precipitation of highly hydrated salts such as meridianiite (MgSO4ṡ11H2O) and MgCl2ṡ12H2O indicate freezing pathway, while precipitation of the low hydrated salts (anhydrite, kieserite and epsomite) indicate evaporation. The present hydration states of the precipitated hydrated minerals probably reflect the ongoing thermal processing and recent seasonally varying humidity conditions at the landing site, but these hydration states might not reflect the original depositional conditions. The simulations also showed the absence of Ca-perchlorate in all models, mainly because of the formation of two main salts: KClO4 and gypsum which are major sinks for ClO-4 and Ca2+ respectively. Finally, in consideration to the Martian life, it might survive at the very low temperatures and low water activities of the liquids formed. However, besides the big and widely recognized challenges to life posed by those extreme environmental parameters (especially low water activity), another main challenge for any form of life in such an environment is to maintain contact with the small droplets of the stable liquids in the regolith and to interact with life in other isolated droplets.

Modified Pechini's method to prepare LaAlO3:RE thermoluminescent materials

NASA Astrophysics Data System (ADS)

Rivera-Montalvo, T.; Morales-Hernandez, A.; Barrera-Angeles, A. A.; Alvarez-Romero, R.; Falcony, C.; Zarate-Medina, J.

2017-11-01

This work presents an alternative method to prepare rare-earth doped lanthanum aluminates materials for thermoluminescent (TL) dosimetry applications. Modified Pechini´s method was using to prepare praseodymium doped LaAlO3 powders. LaAlO3:Pr3+ powders were prepared using La(NO3)3·6H2O, Al(NO3)3·6H2O, Pr(NO3)3·6H2O, citric acid, and ethylene glycol. The solution was heated to 80 °C for its polyesterification reaction. The obtained powders were submitted at different thermal treatment from 700 up to 1600 °C. The structural and morphological characterizations were carried out using X-ray diffraction (XRD) and scanning electron microscopy techniques. TL glow curves of the X-ray irradiated samples showed one peak for europium and praseodymium dopants, meanwhile for powders doped with dysprosium ion showed two peaks. The technique is low cost, faster and it produces homogeneous particles can be used as thermoluminescent phosphors.

Performance of colloidal silica and ceria based slurries on CMP of Si-face 6H-SiC substrates

NASA Astrophysics Data System (ADS)

Chen, Guomei; Ni, Zifeng; Xu, Laijun; Li, Qingzhong; Zhao, Yongwu

2015-12-01

Colloidal silica and ceria based slurries, both using KMnO4 as an oxidizer, for chemical mechanical polishing (CMP) of Si-face (0 0 0 1) 6H-SiC substrate, were investigated to obtain higher material removal rate (MRR) and ultra-smooth surface. The results indicate that there was a significant difference in the CMP performance of 6H-SiC between silica and ceria based slurries. For the ceria based slurries, a higher MRR was obtained, especially in strong acid KMnO4 environment, and the maximum MRR (1089 nm/h) and a smoother surface with an average roughness Ra of 0.11 nm was achieved using slurries containing 2 wt% colloidal ceria, 0.05 M KMnO4 at pH 2. In contrast, due to the attraction between negative charged silica particles and positive charged SiC surface below pH 5, the maximum MRR of silica based slurry was only 185 nm/h with surface roughness Ra of 0.254 nm using slurries containing 6 wt% colloidal silica, 0.05 M KMnO4 at pH 6. The polishing mechanism was discussed based on the zeta potential measurements of the abrasives and the X-ray photoelectron spectroscopy (XPS) analysis of the polished SiC surfaces.

Copper(II) complex with 6-methylpyridine-2-carboxyclic acid: Experimental and computational study on the XRD, FT-IR and UV-Vis spectra, refractive index, band gap and NLO parameters

NASA Astrophysics Data System (ADS)

Altürk, Sümeyye; Avcı, Davut; Başoğlu, Adil; Tamer, Ömer; Atalay, Yusuf; Dege, Necmi

2018-02-01

Crystal structure of the synthesized copper(II) complex with 6-methylpyridine-2-carboxylic acid, [Cu(6-Mepic)2·H2O]·H2O, was determined by XRD, FT-IR and UV-Vis spectroscopic techniques. Furthermore, the geometry optimization, harmonic vibration frequencies for the Cu(II) complex were carried out by using Density Functional Theory calculations with HSEh1PBE/6-311G(d,p)/LanL2DZ level. Electronic absorption wavelengths were obtained by using TD-DFT/HSEh1PBE/6-311G(d,p)/LanL2DZ level with CPCM model and major contributions were determined via Swizard/Chemissian program. Additionally, the refractive index, linear optical (LO) and non-nonlinear optical (NLO) parameters of the Cu(II) complex were calculated at HSEh1PBE/6-311G(d,p) level. The experimental and computed small energy gap shows the charge transfer in the Cu(II) complex. Finally, the hyperconjugative interactions and intramolecular charge transfer (ICT) were studied by performing of natural bond orbital (NBO) analysis.

Copper(II) complex with 6-methylpyridine-2-carboxyclic acid: Experimental and computational study on the XRD, FT-IR and UV-Vis spectra, refractive index, band gap and NLO parameters.

PubMed

Altürk, Sümeyye; Avcı, Davut; Başoğlu, Adil; Tamer, Ömer; Atalay, Yusuf; Dege, Necmi

2018-02-05

Crystal structure of the synthesized copper(II) complex with 6-methylpyridine-2-carboxylic acid, [Cu(6-Mepic) 2 ·H 2 O]·H 2 O, was determined by XRD, FT-IR and UV-Vis spectroscopic techniques. Furthermore, the geometry optimization, harmonic vibration frequencies for the Cu(II) complex were carried out by using Density Functional Theory calculations with HSEh1PBE/6-311G(d,p)/LanL2DZ level. Electronic absorption wavelengths were obtained by using TD-DFT/HSEh1PBE/6-311G(d,p)/LanL2DZ level with CPCM model and major contributions were determined via Swizard/Chemissian program. Additionally, the refractive index, linear optical (LO) and non-nonlinear optical (NLO) parameters of the Cu(II) complex were calculated at HSEh1PBE/6-311G(d,p) level. The experimental and computed small energy gap shows the charge transfer in the Cu(II) complex. Finally, the hyperconjugative interactions and intramolecular charge transfer (ICT) were studied by performing of natural bond orbital (NBO) analysis. Copyright © 2017 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu Huanxin; Liang Yunxiao; Jiang Xiao

A nonmetal pentaborate [C{sub 6}H{sub 13}N{sub 2}][B{sub 5}O{sub 6}(OH){sub 4}] (1) has been synthesized by 1,4-diazabicyclo[2.2.2] octane (DABCO) and boric acid, and characterized by single-crystal X-ray diffraction, FTIR, elemental analysis, and thermogravimetric analysis. Compound 1 crystallizes in the monoclinic system with space group Cc (no. 9), a=10.205(2) A, b=14.143(3) A, c=11.003(2) A, {beta}=113.97(3){sup o}, V=1451.1(5) A{sup 3}, Z=4. The anionic units, [B{sub 5}O{sub 6}(OH){sub 4}]{sup -}, are interlinked via hydrogen bonding to form a three-dimensional (3D) supramolecular network containing large channels, in which the protonated [C{sub 6}H{sub 13}N{sub 2}]{sup +} cations are located. Second-harmonic generation (SHG) measurements on the powdermore » samples reveal that 1 exhibits SHG efficiency approximately 0.9 times that of potassium dihydrogen phosphate (KDP). - Graphical abstract: The protonated [C{sub 6}H{sub 13}N{sub 2}]{sup +} cations and the polyanions [B{sub 5}O{sub 6}(OH){sub 4}]{sup -} form a 3D supramolecular network by extensive hydrogen bonds and electrostatic attraction. This compound shows NLO properties and the SHG efficiency is approximately 0.9 times that of KDP.« less

Negative Ion CID Fragmentation of O-linked Oligosaccharide Aldoses—Charge Induced and Charge Remote Fragmentation

NASA Astrophysics Data System (ADS)

Doohan, Roisin A.; Hayes, Catherine A.; Harhen, Brendan; Karlsson, Niclas Göran

2011-06-01

Collision induced dissociation (CID) fragmentation was compared between reducing and reduced sulfated, sialylated, and neutral O-linked oligosaccharides. It was found that fragmentation of the [M - H]- ions of aldoses with acidic residues gave unique Z-fragmentation of the reducing end GalNAc containing the acidic C-6 branch, where the entire C-3 branch was lost. This fragmentation pathway, which is not seen in the alditols, showed that the process involved charge remote fragmentation catalyzed by a reducing end acidic anomeric proton. With structures containing sialic acid on both the C-3 and C-6 branch, the [M - H]- ions were dominated by the loss of sialic acid. This fragmentation pathway was also pronounced in the [M - 2H]2- ions revealing both the C-6 Z-fragment plus its complementary C-3 C-fragment in addition to glycosidic and cross ring fragmentation. This generation of the Z/C-fragment pairs from GalNAc showed that the charges were not participating in their generation. Fragmentation of neutral aldoses showed pronounced Z-fragmentation believed to be generated by proton migration from the C-6 branch to the negatively charged GalNAc residue followed by charge remote fragmentation similar to the acidic oligosaccharides. In addition, A-type fragments generated by charge induced fragmentation of neutral oligosaccharides were observed when the charge migrated from C-1 of the GalNAc to the GlcNAc residue followed by rearrangement to accommodate the 0,2A-fragmentation. LC-MS also showed that O-linked aldoses existed as interchangeable α/β pyranose anomers, in addition to a third isomer (25% of the total free aldose) believed to be the furanose form.

Selective reductive leaching of cobalt and lithium from industrially crushed waste Li-ion batteries in sulfuric acid system.

PubMed

Peng, Chao; Hamuyuni, Joseph; Wilson, Benjamin P; Lundström, Mari

2018-06-01

Recycling of valuable metals from secondary resources such as waste Li-ion batteries (LIBs) has recently attracted significant attention due to the depletion of high-grade natural resources and increasing interest in the circular economy of metals. In this article, the sulfuric acid leaching of industrially produced waste LIBs scraps with 23.6% cobalt (Co), 3.6% lithium (Li) and 6.2% copper (Cu) was investigated. The industrially produced LIBs scraps were shown to provide higher Li and Co leaching extractions compared to dissolution of corresponding amount of pure LiCoO 2 . In addition, with the addition of ascorbic acid as reducing agent, copper extraction showed decrease, opposite to Co and Li. Based on this, we propose a new method for the selective leaching of battery metals Co and Li from the industrially crushed LIBs waste at high solid/liquid ratio (S/L) that leaves impurities like Cu in the solid residue. Using ascorbic acid (C 6 H 8 O 6 ) as reductant, the optimum conditions for LIBs leaching were found to be T = 80 °C, t = 90 min, [H 2 SO 4 ] = 2 M, [C 6 H 8 O 6 ] = 0.11 M and S/L = 200 g/L. This resulted in leaching efficiencies of 95.7% for Li and 93.8% for Co, whereas in contrast, Cu extraction was only 0.7%. Consequently, the proposed leaching method produces a pregnant leach solution (PLS) with high Li (7.0 g/L) and Co (44.4 g/L) concentration as well as a leach residue rich in Cu (up to 12 wt%) that is suitable as a feed fraction for primary or secondary copper production. Copyright © 2018 Elsevier Ltd. All rights reserved.

Growth of nitric acid hydrates on thin sulfuric acid films

NASA Technical Reports Server (NTRS)

Iraci, Laura T.; Middlebrook, Ann M.; Wilson, Margaret A.; Tolbert, Margaret A.

1994-01-01

Type I polar stratospheric clouds (PSCs) are thought to nucleate and grow on stratospheric sulfate aerosols (SSAs). To model this system, thin sulfuric acid films were exposed to water and nitric acid vapors (1-3 x 10(exp -4) Torr H2O and 1-2.5 x 10(exp -6) Torr HNO3) and subjected to cooling and heating cycles. Fourier Transform Infrared (FTIR) spectroscopy was used to probe the phase of the sulfuric acid and to identify the HNO3/H2O films that condensed. Nitric acid trihydrate (NAT) was observed to grow on crystalline sulfuric acid tetrahydrate (SAT) films. NAT also condensed in/on supercooled H2SO4 films without causing crystallization of the sulfuric acid. This growth is consistent with NAT nucleation from ternary solutions as the first step in PSC formation.

Molecular Organization of Cholesterol in Docosahexaenoate-Rich Lipid Bilayers

NASA Astrophysics Data System (ADS)

Wassall, Stephen R.; Brzustowicz, Michael R.; Cherezov, Vadim; Caffrey, Martin; Zerouga, Mustapha; Stillwell, William

2002-03-01

We investigated the molecular organization of cholesterol in 1,2-didocosahexaenoylphosphatidylcholine (22:6-22:6PC) and 1-stearoyl-2-docosahexaenoylphosphatidylcholine (18:0-22:6PC) bilayers. The solubility of the sterol measured by wide-angle x-ray diffraction was < 20 mol% in 22:6-22:6PC bilayers which contrasts with > 50 mol% in 18:0-22:6PC. Solid state ^2H NMR of [3α-^2H_1]cholesterol suggests that the reduction in solubility correlates with a larger tilt angle α0 = 24^o for the steroid moiety in 22:6-22:6PC bilayers than in 18:0-22:6PC where α0 < 24^o. We attribute the low solubility of cholesterol in 22:6-22:6PC membranes to steric incompatibility between the rigid steroid moiety and the highly polyunsaturated docosahexaenoic acid (DHA) chain, which has the potential to promote lateral heterogeneity within neural membranes rich in DHA and has implications for receptor activation.

Transformation of polyfluorinated compounds in natural waters by advanced oxidation processes.

PubMed

Anumol, Tarun; Dagnino, Sonia; Vandervort, Darcy R; Snyder, Shane A

2016-02-01

The presence of perfluorocarboxylic acids (PFCAs) in source and finished drinking waters is a concern with studies showing bioaccumulation and adverse toxicological effects in wildlife and potentially humans. Per/Polyfluoroalkyl substances (PFAS) such as fluorotelomer alcohols have been identified as precursors for PFCAs in biological pathways. In this study, we investigated the fate of 6:2 and 8:2 homologues of the fluorotelomer unsaturated carboxylic acids (FTUCAs) during advanced oxidation process (AOPs). Results showed 6:2 FTUCA and 8:2 FTUCA transformed into 6-C PFCA (PFHxA) and 8-C PFCA (PFOA) respectively with very little other PFCA formation for all AOPs. The degradation of 6:2 FTUCA and 8:2 FTUCA was greater in the GW compared to SW for the ozone processes but similar for UV/H2O2. The formation of n-C PFCA followed O3>O3/H2O2 at same dose and UV/H2O2 had much lower formation at the doses tested. Non-targeted analysis with the LC-MS-qTOF indicated the production of other PFCAs which contribute to the total mass balance, although no intermediate product was discovered indicating a rapid and direct transformation from the FTUCAs to the PFCAs and/or significant volatilization of intermediates. With the use of AOPs essential to water reuse treatment schemes, this work raises concerns over the risk of potential formation of PFCAs in the treatment and their adverse health effects in finished drinking water. Copyright © 2015 Elsevier Ltd. All rights reserved.

Connectivity patterns and rotamer states of nucleobases determine acid-base properties of metalated purine quartets.

PubMed

Lüth, Marc Sven; Freisinger, Eva; Kampf, Gunnar; Garijo Anorbe, Marta; Griesser, Rolf; Operschall, Bert P; Sigel, Helmut; Lippert, Bernhard

2015-07-01

Potentiometric pH titrations and pD dependent (1)H NMR spectroscopy have been applied to study the acidification of the exocyclic amino group of adenine (A) model nucleobases (N9 position blocked by alkyl groups) when carrying trans-a2Pt(II) (with a=NH3 or CH3NH2) entities both at N1 and N7 positions. As demonstrated, in trinuclear complexes containing central A-Pt-A units, it depends on the connectivity pattern of the adenine bases (N7/N7 or N1/N1) and their rotamer states (head-head or head-tail), how large the acidifying effect is. Specifically, a series of trinuclear complexes with (A-N7)-Pt-(N7-A) and (A-N1)-Pt-(N1-A) cross-linking patterns and terminal 9-alkylguanine ligands (9MeGH, 9EtGH) have been analyzed in this respect, and it is shown that, for example, the 9MeA ligands in trans-,trans-,trans-[Pt(NH3)2(N7-9MeA-N1)2{Pt(NH3)2(9EtGH-N7)}2](ClO4)6·6H2O (4a) and trans-,trans-,trans-[Pt(NH3)2(N7-9EtA-N1)2{Pt(CH3NH2)2(9-MeGH-N7)}2](ClO4)6·3H2O (4b) are more acidic, by ca. 1.3 units (first pKa), than the linkage isomer trans-,trans-,trans-[Pt(CH3NH2)2(N1-9MeA-N7)2{Pt(NH3)2(9MeGH-N7)}2](NO3)6·6.25H2O (1b). Overall, acidifications in these types of complexes amount to 7-9 units, bringing the pKa values of such adenine ligands in the best case close to the physiological pH range. Comparison with pKa values of related trinuclear Pt(II) complexes having different co-ligands at the Pt ions, confirms this picture and supports our earlier proposal that the close proximity of the exocyclic amino groups in a head-head arrangement of (A-N7)-Pt-(N7-A), and the stabilization of the resulting N6H(-)⋯H2N6 unit, is key to this difference. Copyright © 2015 Elsevier Inc. All rights reserved.

Dimensional modulation and magnetic properties of triazole- and bis(triazole)-based copper(II) coordination polymers tuned by aromatic polycarboxylates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Ju-Wen; Zhao, Wei; Lu, Qi-Lin

2014-04-01

Five new metal–organic coordination polymers ([Cu{sub 3}(μ{sub 2}-OH){sub 2}(atrz){sub 2}(nph){sub 2}(H{sub 2}O){sub 2}]·2H{sub 2}O){sub n} (1), ([Cu{sub 2}(μ{sub 3}-OH)(atrz)(1,2,4-btc)]·2H{sub 2}O){sub n} (2), ([Cu{sub 2}(μ{sub 3}-OH)(atrz)(1,2,4-btc)(H{sub 2}O)]·H{sub 2}O){sub n} (3), [Cu(dth){sub 0.5}(nph)(H{sub 2}O)]{sub n} (4) and [Cu(dth)(Hnip){sub 2}]{sub n} (5) [atrz=4-amino-1,2,4-triazole, dth=N,N'-di(4H-1,2,4-triazole)hexanamide, H{sub 2}nph=3-nitrophthalic acid, 1,2,4-H{sub 3}btc=1,2,4-benzenetricarboxylic acid and H{sub 2}nip=5-nitroisophthalic acid] were hydrothermally synthesized and structurally characterized. Polymer 1 shows a one-dimensional (1D) chain. Polymers 2 and 3 exhibit similar tetranuclear Cu{sup II}{sub 4} cluster-based three-dimensional (3D) frameworks with the same components. Polymer 4 possesses a 3D framework with a 4{sup 12}·6{sup 3}-pcu topology. Polymer 5 displays a 3D frameworkmore » with a 4{sup 4}·6{sup 10}·8-mab topology. The magnetic properties of 1–4 were investigated. - Graphical abstract: Five triazole-based copper(II) polymers modulated by polycarboxylates were synthesized. Bis-triazole-bis-amide ligand and polycarboxylates play important roles in tuning dimensionality of polymers. Magnetic properties of polymers were investigated. - Highlights: • Five triazole- and bis(triazole)-based copper(II) coordination polymers tuned by aromatic polycarboxylates were obtained. • The aromatic polycarboxylates have an important influence on the dimensionality of five polymers. • The magnetic properties of four polymers were investigated.« less

Relatedness of the O-polysaccharide structures of Escherichia coli O123 and Salmonella enterica O58, both containing 4,6-dideoxy-4-{N-[(S)-3-hydroxybutanoyl]-D-alanyl}amino-D-glucose; revision of the E. coli O123 O-polysaccharide structure.

PubMed

Perepelov, Andrei V; Liu, Bin; Shevelev, Sergei D; Senchenkova, Sof'ya N; Shashkov, Alexander S; Feng, Lu; Knirel, Yuriy A; Wang, Lei

2010-04-19

O-Polysaccharides were isolated by mild acid degradation of the lipopolysaccharides of Escherichia coli O123 and Salmonella enterica O58 and studied by chemical methods and 2D (1)H and (13)C NMR spectroscopy, including experiments in a H(2)O/D(2)O mixture, which enabled observation of correlations for nitrogen-linked protons. The following structure of the O-polysaccharide of E. coli O123 was established: -->3)-beta-D-Quip4NAlaHb-(1-->6)-alpha-D-GlcpNAc-(1-->3)-alpha-L-QuipNAc-(1-->3)-alpha-D-Glcp (6)(approx. 30% OAc)NAc-(1--> where L-QuipNAc stands for 2-acetamido-2,6-dideoxy-L-glucose and D-Qui4NAlaHb for 4-{N-[(S)-3-hydroxybutanoyl]-D-alanyl}amino-4,6-dideoxy-D-glucose. The latter was isolated as an ethylene glycol glycoside by three sequential Smith degradations of the O-deacetylated O-polysaccharide. The structure established in this work is at variance with the E. coli O123-polysaccharide structure reported earlier [Clark, C. G.; Kropinski, A. M.; Parolis, H.; Grant, C. C.; Trout-Yakel, K. M.; Franklin, K.; Ng, L. K.; Paramonov, N. A.; Parolis, L. A.; Rahn, K.; Tabor, H. J. Med. Microbiol.2009, 58, 884-894]. In accordance with the genetic data, the O-polysaccharide of S. enterica O58 has the same structure, except for it lacks the O-acetylation. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Synthesis and structure of a heptanuclear nickel(II) complex uniquely exhibiting four distinct binding modes, two of which are novel, for a hydroxamate ligand.

PubMed

Gaynor, Declan; Starikova, Zoya A; Ostrovsky, Sergei; Haase, Wolfgang; Nolan, Kevin B

2002-03-07

The reaction of 2-(dimethylamino)phenylhydroxamic acid (2-dmAphaH) with NiSO(4).6H2O gives the complex [Ni7(2-dmAphaH-1)2(2-dmApha)8(H2O)2]SO(4).15H2O uniquely exhibiting four distinct hydroxamate binding modes, two of which are novel, and showing both antiferromagnetic and ferromagnetic interactions in contrast to [Cu5(2-dmAphaH-1)4(HSO4)2(MeOH)2].2MeOH, a strongly antiferromagnetic metallacrown formed with CuSO(4).5H2O.

Sensitivity and selectivity of switchable reagent ion soft chemical ionization mass spectrometry for the detection of picric acid.

PubMed

Agarwal, Bishu; González-Méndez, Ramón; Lanza, Matteo; Sulzer, Philipp; Märk, Tilmann D; Thomas, Neil; Mayhew, Chris A

2014-09-18

We have investigated the reactions of NO(+), H3O(+), O2(+), and Kr(+) with picric acid (2,4,6 trinitrophenol, C6H3N3O7, PiA) using a time-of-flight mass spectrometer with a switchable reagent ion source. NO(+) forms a simple adduct ion PiA·NO(+), while H3O(+) reacts with PiA via nondissociative proton transfer to form PiAH(+). In contrast, both O2(+) and Kr(+) react with PiA by nondissociative charge transfer to produce PiA(+). For Kr(+), we also observe dissociation of PiA, producing NO2(+) with a branching percentage of approximately 40%. For the reagent ions H3O(+) and O2(+) (and operating the drift tube with normal laboratory air), we find that the intensities of the PiAH(+) and PiA(+) ions both exhibit a peak at a given drift-tube voltage (which is humidity dependent). This unusual behavior implies a peak in the detection sensitivity of PiA as a function of the drift-tube voltage (and hence E/N). Aided by electronic-structure calculations and our previous studies of trinitrotoluene and trinitrobenzene, we provide a possible explanation for the observed peak in the detection sensitivity of PiA.

Characterization of the activity of L-ascorbic acid 2-[3,4-dihydro-2,5,7,8-tetramethyl-2-(4,8,12-trimethyltridecyl)-2H-1-be nzopyran-6-yl-hydrogen phosphate] potassium salt in hydroxyl radical elimination.

PubMed

Tomita, T; Kashima, M; Tsujimoto, Y

2000-03-01

The effect of L-ascorbic acid 2-[3,4-dihydro-2,5,7,8-tetramethyl-2-(4,8,12-trimethyltridecyl)-2H -1-benzopyran-6-yl-hydrogen phosphate] potassium salt (EPC-K1) on hydroxyl radical (*OH) elimination was studied using electron spin resonance (ESR) and spectrophotometric experiments. The addition of EPC-K, and *OH scavengers eliminated the *OH generated from Cu2+/H2O2, Fe2+/H2O2 and H2O2/UV-irradiation reaction systems. However, in competitive reactions using different concentrations of a spin-trap agent, the addition of the *OH scavenger altered the IC50 values, whereas the addition of EPC-K1 and a metal chelater did not change the value in the Cu2+/H2O2 and Fe2+/H2O2 reaction systems. The addition of EPC-K1 and metal chelater changed the ESR signal for free Cu2+. The spectrophotometric experiments confirmed that the addition of EPC-K1 and metal chelater altered the absorption spectra due to CuCl2 and FeSO4, whereas the *OH scavenger did not alter the spectra. Therefore, it was demonstrated that EPC-K, has the ability both to scavenge *OH directly and to inhibit the generation of *OH by the chelation of Cu2+ and Fe2+.

Free Radical Scavenging Properties of Skin and Pulp Extracts of Different Grape Cultivars In Vitro and Attenuation of H2O2-Induced Oxidative Stress in Liver Tissue Ex Vivo.

PubMed

Singha, Indrani; Das, Subir Kumar

2015-07-01

Grapes are the richest source of antioxidants due to the presence of potent bioactive phytochemicals. In this study, the phytochemical contents, scavenging activities and protective role against H2O2-induced oxidative stress in liver tissue ex vivo of four grape (Vitis vinifera) cultivars extracts, namely Flame seedless (black), Kishmish chorni (black with reddish brown), Red globe (red) and Thompson seedless mutant (green), were evaluated. The total phenolics and flavonoids content in pulp or skin fractions of different grape cultivars were in the range of 47.6-310 mg gallic acid equivalent/g fresh weight (fw), and 46.6-733.3 µg catechin equivalent/g fw respectively. The scavenging activities in skin of different grape varieties against 2,2-diphenyl-1-picrylhydrazyl (44-58 %), hydrogen peroxide (15.3-18.6 %), and hydroxyl radicals (50-85 %), were higher than pulp of the corresponding cultivars. These scavenging activities of grape extracts were found to be significantly (p < 0.01) correlated with the levels of total phenols, flavonoids and ascorbic acid. Liver tissues from goat treated with H2O2 (500 μM) showed significantly decreased GSH content by 42.9 % and activities of catalase by 50 % and glutathione reductase by 66.6 %; while increased thiobarbituric acid reactive substances and nitric oxide level by 2.53- and 0.86-fold, respectively, and activity of glutathione S-transferase by 0.96-fold. Grape skin extracts showed the stronger protective activity against H2O2-induced oxidative stress in liver tissue ex vivo, than its pulp of any cultivar; and the Flame seedless (black) cultivar showed the highest potential. In conclusion, our study suggested that the higher antioxidant potential, phytochemical contents and significant scavenging capacities in pulp and skin of grape extracts showed the protective action of grape extracts against H2O2-induced oxidative stress in liver tissue ex vivo.

Peroxisomal fatty acid oxidation as detected by H2O2 production in intact perfused rat liver.

PubMed Central

Foerster, E C; Fährenkemper, T; Rabe, U; Graf, P; Sies, H

1981-01-01

1. H2O2 formation associated with the metabolism of added fatty acids was quantitatively determined in isolated haemoglobin-free perfused rat liver (non-recirculating system) by two different methods. 2. Organ spectrophotometry of catalase Compound I [Sies & Chance (1970) FEBS Lett. 11, 172-176] was used to detect H2O2 formation (a) by steady-state titration with added hydrogen donor, methanol or (b) by comparison of fatty-acid responses with those of the calibration compound, urate. 3. In the use of the peroxidatic reaction of catalase, [14C]methanol was added as hydrogen donor at an optimal concentration of 1 mM in the presence of 0.2 mM-L-methionine, and 14CO2 production rates were determined. 4. Results obtained by the different methods were similar. 5. The yield of H2O2 formation, expressed as the rate of H2O2 formation in relation to the rate of fatty-acid supply, was less than 1.0 in all cases, indicating that, regardless of chain length, less than one acetyl unit was formed per mol of added fatty acid by the peroxisomal system. In particular, the standard substrate used with isolated peroxisomal preparations (C16:0 fatty acid) gave low yield (close to zero). Long-chain monounsaturated fatty acids exhibit a relatively high yield of H2O2 formation. 6. The hypolipidaemic agent bezafibrate led to slightly increased yields for most of the acids tested, but the yield with oleate was decreased to one-half the original yield. 7. It is concluded that in the intact isolated perfused rat liver the assayable capacity for peroxisomal beta-oxidation is used to only a minor degree. However, the observed rates of H2O2 production with fatty acids can account for a considerable share of the endogenous H2O2 production found in the intact animal. PMID:7317011

Discrete hexamer water clusters and 2D water layer trapped in three luminescent Ag/tetramethylpyrazine/benzene-dicarboxylate hosts: 1D chain, 2D layer and 3D network

NASA Astrophysics Data System (ADS)

Mei, Hong-Xin; Zhang, Ting; Huang, Hua-Qi; Huang, Rong-Bin; Zheng, Lan-Sun

2016-03-01

Three mix-ligand Ag(I) coordination compounds, namely, {[Ag10(tpyz) 5(L1) 5(H2 O)2].(H2 O)4}n (1, tpyz = 2,3,4,5-tetramethylpyrazine, H2 L1 = phthalic acid), [Ag4(tpyz) 2(L2) 2(H2 O)].(H2 O)5}n (2, H2 L2 = isophthalic acid) {[Ag2(tpyz) 2(L3) (H2 O)4].(H2 O)8}n (3, H2 L3 = terephthalic acid), have been synthesized and characterized by elemental analysis, IR, PXRD and X-ray single-crystal diffraction. 1 exhibits a 2D layer which can be simplified as a (4,4) net. 2 is a 3D network which can be simplified as a (3,3)-connected 2-nodal net with a point symbol of {102.12}{102}. 3 consists of linear [Ag(tpyz) (H2 O)2]n chain. Of particular interest, discrete hexamer water clusters were observed in 1 and 2, while a 2D L10(6) water layer exists in 3. The results suggest that the benzene dicarboxylates play pivotal roles in the formation of the different host architectures as well as different water aggregations. Moreover, thermogravimetric analysis (TGA) and emissive behaviors of these compounds were investigated.

Photochemistry of the alkaloids eudistomin N (6-bromo-nor-harmane) and eudistomin O (8-bromo-nor-harmane) and other bromo-beta-carbolines.

PubMed

Tarzi, Olga I; Erra-Balsells, Rosa

2005-07-01

The UV-absorption, fluorescence excitation and emission spectra of the alkaloids eudistomin N (6-bromo-nor-harmane) and eudistomin O (8-bromo-nor-harmane) were described. In order to perform a comparative analysis, we also studied other bromo-beta-carbolines and the corresponding non-substituted-carboline. Thus, 6-bromo-, 8-bromo-, 6,8-dibromo-, 3,6-dibromo- and 3,6,8-tribromo-derivatives of nor-harmane, harmane and harmine were studied. These studies were performed in EtOH and in EtOH + 1% perchloric acid solutions (pa). Furthermore, fluorescence quantum yields (phi(f)) in acetonitrile and acetonitrile + 1% perchloric acid solutions at 298 K were measured. The HOMO and LUMO energy, the positions (lambda(max)) and oscillator strength (f) of the (1)S(1) <--(1)S(0) band for all the neutral and protonated beta-carbolines studied was calculated and compared with the experimental data. The pK(a) values in aqueous solution for eudistomin N and O (6-bromo- and 8-bromo-nor-harmane), for 6-bromo-, 8-bromo- and 6,8-dibromo-harmane, and for 6-bromo- and 8-bromo-harmine were spectrophotometrically measured (pK((a)(H(2)O))) . The change of the acid-base character of these compounds on going from the ground state (pK(a)) to the first electronic excited singlet state (pK(a)(*)) as DeltapK(a) = pK(a)(*)-pK(a) = 0.625 Deltanu /T, in ethanol solution at 298 K were calculated (DeltapK(a(EtOH))). Proton affinities (PA) for all the compounds studied defined as minus the enthalpy change of the reaction M+H(+)--> MH(+) (gas state) were calculated. Basicity relative to pyridine (DeltaH(rPy)) defined as the enthalpy change of the isodesmic reaction MH(+) + Py--> M + PyH(+) (gas state) was also calculated. The effect of bromine as substituent on the properties of the beta-carboline moiety in nor-harmane, harmane and harmine is discussed.

Cerium-Hydride Secondary Building Units in a Porous Metal–Organic Framework for Catalytic Hydroboration and Hydrophosphination

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ji, Pengfei; Sawano, Takahiro; Lin, Zekai

2016-11-16

We report the stepwise, quantitative transformation of CeIV6(μ3-O)4(μ3-OH)4(OH)6(OH2)6 nodes in a new Ce-BTC (BTC = trimesic acid) metal–organic framework (MOF) into the first CeIII6(μ3-O)4(μ3-OLi)4(H)6(THF)6Li6 metal-hydride nodes that effectively catalyze hydroboration and hydrophosphination reactions. CeH-BTC displays low steric hindrance and electron density compared to homogeneous organolanthanide catalysts, which likely accounts for the unique 1,4-regioselectivity for the hydroboration of pyridine derivatives. MOF nodes can thus be directly transformed into novel single-site solid catalysts without homogeneous counterparts for sustainable chemical synthesis.

The effect of pH on N2O production under aerobic conditions in a partial nitritation system.

PubMed

Law, Yingyu; Lant, Paul; Yuan, Zhiguo

2011-11-15

Ammonia-oxidising bacteria (AOB) are a major contributor to nitrous oxide (N(2)O) emissions during nitrogen transformation. N(2)O production was observed under both anoxic and aerobic conditions in a lab-scale partial nitritation system operated as a sequencing batch reactor (SBR). The system achieved 55 ± 5% conversion of the 1g NH(4)(+)-N/L contained in a synthetic anaerobic digester liquor to nitrite. The N(2)O emission factor was 1.0 ± 0.1% of the ammonium converted. pH was shown to have a major impact on the N(2)O production rate of the AOB enriched culture. In the investigated pH range of 6.0-8.5, the specific N(2)O production was the lowest between pH 6.0 and 7.0 at a rate of 0.15 ± 0.01 mg N(2)O-N/h/g VSS, but increased with pH to a maximum of 0.53 ± 0.04 mg N(2)O-N/h/g VSS at pH 8.0. The same trend was also observed for the specific ammonium oxidation rate (AOR) with the maximum AOR reached at pH 8.0. A linear relationship between the N(2)O production rate and AOR was observed suggesting that increased ammonium oxidation activity may have promoted N(2)O production. The N(2)O production rate was constant across free ammonia (FA) and free nitrous acid (FNA) concentrations of 5-78 mg NH(3)-N/L and 0.15-4.6 mg HNO(2)-N/L, respectively, indicating that the observed pH effect was not due to changes in FA or FNA concentrations. Copyright © 2011 Elsevier Ltd. All rights reserved.

Infrared predissociation spectroscopy of M+ (C6H6)(1-4)(H2O)(1-2)Ar(0-1) cluster ions, M = Li, Na.

PubMed

Beck, Jordan P; Lisy, James M

2011-05-05

Infrared predissociation (IRPD) spectra of Li(+)(C(6)H(6))(1-4)(H(2)O)(1-2)Ar(0-1) and Na(+)(C(6)H(6))(2-4)(H(2)O)(1-2)Ar(1) are presented along with ab initio calculations. The results indicate that the global minimum energy structure for Li(+)(C(6)H(6))(2)(H(2)O)(2) has each water forming a π-hydrogen bond with the same benzene molecule. This bonding motif is preserved in Li(+)(C(6)H(6))(3-4)(H(2)O)(2)Ar(0-1) with the additional benzene ligands binding to the available free OH groups. Argon tagging allows high-energy Li(+)(C(6)H(6))(2-4)(H(2)O)(2)Ar isomers containing water-water hydrogen bonds to be trapped and detected. The monohydrated, Li(+) containing clusters contain benzene-water interactions with varying strength as indicated by shifts in OH stretching frequencies. The IRPD spectra of M(+)(C(6)H(6))(1-4)(H(2)O)(1-2)Ar are very different for lithium-bearing versus sodium-bearing cluster ions emphasizing the important role of ion size in determining the most favorable balance of competing noncovalent interactions.

Structural Diversities in Heterometallic Mn-Ca Cluster Chemistry from the Use of Salicylhydroxamic Acid: {MnIII4Ca2}, {MnII/III6Ca2}, {MnIII/IV8Ca}, and {MnIII8Ca2} Complexes with Relevance to Both High- and Low-Valent States of the Oxygen-Evolving Complex.

PubMed

Alaimo, Alysha A; Koumousi, Evangelia S; Cunha-Silva, Luís; McCormick, Laura J; Teat, Simon J; Psycharis, Vassilis; Raptopoulou, Catherine P; Mukherjee, Shreya; Li, Chaoran; Gupta, Sayak Das; Escuer, Albert; Christou, George; Stamatatos, Theocharis C

2017-09-05

One-pot reactions between the [Mn 3 O(O 2 CPh) 6 (py) x ] +/0 triangular precursors and either CaBr 2 ·xH 2 O or CaCl 2 ·6H 2 O, in the presence of salicylhydroxamic acid (shaH 2 ), have afforded the heterometallic complexes [Mn III 4 Ca 2 (O 2 CPh) 4 (shi) 4 (H 2 O) 3 (Me 2 CO)] (1) and (pyH)[Mn II 2 Mn III 4 Ca 2 Cl 2 (O 2 CPh) 7 (shi) 4 (py) 4 ] (2), respectively, in good yields. Further reactions but using a more flexible synthetic scheme comprising the Mn(NO 3 ) 2 ·4H 2 O/Ca(NO 3 ) 2 ·4H 2 O and Mn(O 2 CPh) 2 ·2H 2 O/Ca(ClO 4 ) 2 ·4H 2 O "metal blends" and shaH 2 , in the presence of external base NEt 3 , led to the new complexes (NHEt 3 ) 2 [Mn III 4 Mn IV 4 Ca(OEt) 2 (shi) 10 (EtOH) 2 ] (3) and (NHEt 3 ) 4 [Mn III 8 Ca 2 (CO 3 ) 4 (shi) 8 ] (4), respectively. In all reported compounds, the anion of the tetradentate (N,O,O,O)-chelating/bridging ligand salicylhydroxime (shi 3- ), resulting from the in situ metal-ion-assisted amide-iminol tautomerism of shaH 2 , was found to bridge both Mn and Ca atoms. Complexes 1-4 exhibit a variety of different structures, metal stoichiometries, and Mn oxidation-state descriptions; 1 possesses an overall octahedral metal arrangement, 2 can be described as a Mn 4 Ca 2 octahedron bound to an additional Mn 2 unit, 3 consists of a Mn 8 "ring" surrounding a Ca II atom, and 4 adopts a rectangular cuboidal motif of eight Mn atoms accommodating two Ca II atoms. Solid-state direct-current magnetic susceptibility studies revealed the presence of predominant antiferromagnetic exchange interactions between the Mn centers, leading to S = 0 spin ground-state values for all complexes. From a bioinorganic chemistry perspective, the reported compounds may demonstrate some relevance to both high-valent scheme (3) and lower-oxidation-level species (1, 2, and 4) of the catalytic cycle of the oxygen-evolving complex.

Structural, spectral and magnetic studies of two Co(II)-N-heterocyclic diphosphonates based on multinuclear units

NASA Astrophysics Data System (ADS)

Zhao, Chen; Ma, Kui-Rong; Zhang, Yu; Kan, Yu-He; Li, Rong-Qing; Hu, Hua-You

2016-01-01

Two examples of Co(II)-N-heterocyclic coordination polymers based on 1-hydroxyethylidenediphosphonic acid (H5L = CH3C(OH)(PO3H2)2), namely 0.5(H3NCH2CH2NH3)·[Co6(Cl2)(H3L)2(H2L)(HL)(2,2‧-bipy)6] 1 and 2(NH4)·[Co3(HL)2(H2O)2(phen)2]·2(H2O) 2, have been solvothermally obtained by introducing the second ligands 2,2‧-bipyridine/1,10-phenanthroline (2,2‧-bipy/phen) and characterized by powder X-ray diffraction (PXRD), elemental analysis, IR, TG-DSC. The single-crystal X-ray diffractions show that compound 1 possesses a 0-D structure with hexa-nuclear cluster [Co6(O-P-O)8] built through single/double O-P-O bridges and compound 2 displays a 1-D ladder-like chain structure with magnetic topology building blocks [Co4(O-P-O)4]n. Then H-bonding and π-π stacking interactions further expand the two low-dimensional structures into three-dimensional supramolecular frameworks. Fluorescent measurements reveal that both the maximum emission peaks of 1-2 are centered at 423 nm, mainly deriving from intraligand π*-π transition state of N-heterocyclic ligand 2,2‧-bipy/phen, respectively. Magnetism data indicate that 1 exhibits antiferromagnetic behavior within hexa-nuclear Co(II) clusters, while 2 shows weak ferromagnetic interactions in 1-D topology Co(II)-chain, showing promising potential as magnetic materials.

Selenate as a novel ligand for keplerate chemistry. New {W72Mo60} keplerates with selenates inside the cavity.

PubMed

Korenev, Vladimir S; Abramov, Pavel A; Vicent, Cristian; Zhdanov, Artem A; Tsygankova, Alphiya R; Sokolov, Maxim N; Fedin, Vladimir P

2015-05-21

The synthesis and characterization of three novel keplerate-type compounds containing the {W72Mo60} mixed-metal core are reported. Complexes (NH4)72[{W6O21(H2O)6}12{Mo2O4(SeO4)}30]·150H2O·6(NH4)2SeO4 (1a) and (NH4)25(NH2Me2)47[{W6O21(H2O)6}12{Mo2O4(SeO4)}30]·130H2O·3(NH4)2SeO4 (1b) were prepared by ligand substitution from the acetate anionic complex [{W6O21(H2O)5(CH3COO)0.5}12{Mo2O4(CH3COO)}30](48-) and selenate. The selenate anions in keplerate ions [{W6O21(H2O)6}12{Mo2O4(SeO4)}30](72-) are very labile and easily aquate with the formation of [{W6O21(H2O)6}12{Mo2O4}30(SeO4)20(H2O)20](52-), which was isolated as (NH4)20(NH2Me2)32[{W6O21(H2O)6}12{Mo2O4}30(SeO4)20(H2O)20]·150H2O (2) and structurally characterized. In the crystal structure of 2 selenate has several coordination modes, preferentially bonding to the {Mo2O4}(2+) units, and, additionally, to the {(W)W5} pentagonal blocks. The compounds have been characterized by elemental analysis, Raman, IR and (77)Se NMR spectroscopy, and by ESI mass spectrometry. Capillary electrophoresis was used for characterization of keplerates in solution for the first time.

Spectroscopic and DFT Study of RhIII Chloro Complex Transformation in Alkaline Solutions.

PubMed

Vasilchenko, Danila B; Berdyugin, Semen N; Korenev, Sergey V; O'Kennedy, Sean; Gerber, Wilhelmus J

2017-09-05

The hydrolysis of [RhCl 6 ] 3- in NaOH-water solutions was studied by spectrophotometric methods. The reaction proceeds via successive substitution of chloride with hydroxide to quantitatively form [Rh(OH) 6 ] 3- . Ligand substitution kinetics was studied in an aqueous 0.434-1.085 M NaOH matrix in the temperature range 5.5-15.3 °C. Transformation of [RhCl 6 ] 3- into [RhCl 5 (OH)] 3- was found to be the rate-determining step with activation parameters of ΔH † = 105 ± 4 kJ mol -1 and ΔS † = 59 ± 10 J K -1 mol -1 . The coordinated hydroxo ligand(s) induces rapid ligand substitution to form [Rh(OH) 6 ] 3- . By simulating ligand substitution as a dissociative mechanism, using density functional theory (DFT), we can now explain the relatively fast and slow kinetics of chloride substitution in basic and acidic matrices, respectively. Moreover, the DFT calculated activation energies corroborated experimental data that the kinetic stereochemical sequence of [RhCl 6 ] 3- hydrolysis in an acidic solution proceeds as [RhCl 6 ] 3- → [RhCl 5 (H 2 O)] 2- → cis-[RhCl 4 (H 2 O) 2 ] - . However, DFT calculations predict in a basic solution the trans route of substitution [RhCl 6 ] 3- → [RhCl 5 (OH)] 3- → trans-[RhCl 4 (OH) 2 ] 3- is kinetically favored.

Crystal structure, quantum mechanical investigation, IR and NMR spectroscopy of two new organic perchlorates: (C6H18N3)·(ClO4)3H2O (I) and (C9H11N2)·ClO4(II)

NASA Astrophysics Data System (ADS)

Bayar, I.; Khedhiri, L.; Soudani, S.; Lefebvre, F.; Ferretti, V.; Ben Nasr, C.

2018-06-01

The reaction of perchloric acid with 1-(2-aminoethyl)piperazine or 5,6-dimethyl-benzimidazole results in the formation of 1-(2-amonioethyl)piperazine-1,4-dium triperchlorate hydrate (C6H18N3)·(ClO4)3·H2O (I) or 5,6-dimethyl-benzylimidazolium perchlorate (C9H11N2)·ClO4(II). Both compounds were fully structurally characterized including single crystal X-ray diffraction analysis. Compound (I) crystallizes in the centrosymmetric triclinic space group P 1 bar with the lattice parameters a = 7.455 (2), b = 10.462 (2), c = 10.824 (2) Å, α = 80.832 (2), β = 88.243 (2), γ = 88.160 (2) °, Z = 2 and V = 832.77 (3) Å3. Compound (II) has been found to belong to the P21/c space group of the monoclinic system, with a = 7.590 (3), b = 9.266 (3), c = 16.503 (6) Å, β = 107.38 (2) °, V = 1107.69 (7) Å3 and Z = 4. The structures of (I) and (II) consist of slightly distorted [ClO4]- tetrahedra anions and 1-(2-amonioethyl)piperazine-1,4-dium trication (I) or 5,6-dimethyl-benzylimidazolium cations (II) and additionally a lattice water in (I). The crystal structures of (I) and (II) exhibit complex three-dimensional networks of H-bonds connecting all their components. In the atomic arrangement of (I), the ClO4- anions form corrugated chains, while in (II) the atomic arrangement exhibits wide pseudo-hexagonal channels of ClO4 tetrahedra including the organic entities. The lattice water serves as a link between pairs of cations and pairs of anions via several Osbnd H⋯O and N-H⋯O interactions in compound (I). The vibrational absorption bands were identified by infrared spectroscopy. These compounds were also investigated by solid-state 13C, 35Cl and 15N NMR spectroscopy. DFT calculations allowed the attribution of the IR and NMR bands. Intermolecular interactions were investigated by Hirshfeld surfaces. Electronic properties such as HOMO and LUMO energies were derived.

Hydrothermal Syntheses and Structures of Three-Dimensional Oxo-fluorovanadium Phosphates: [H 2N(C 2H 4) 2NH 2] 0.5[(VO) 4V(HPO 4) 2(PO 4) 2F 2(H 2O) 4] · 2H 2O and K 2[(VO) 3(PO 4) 2F 2(H 2O)] · H 2O

NASA Astrophysics Data System (ADS)

Bonavia, Grant; Haushalter, R. C.; Zubieta, Jon

1996-11-01

The hydrothermal reactions of FPO3H2with vanadium oxides result in the incorporation of fluoride into V-P-O frameworks as a consequence of metal-mediated hydrolysis of the fluorophosphoric acid to produce F-and PO3-4. By exploiting this convenient source of F-, two 3-dimensional oxo-fluorovanadium phosphate phases were isolated, [H2N(C2H4)2NH2]0.5[(VO)4V(HOP4)2(PO4)2F2(H2O)4) · 2H2O (1 · 2H2O) and K2[(VO)3(PO4)2F2(H2O)] · H2O (2 · H2O). Both anionic frameworks contain (VIVO)-F--phosphate layers, with confacial bioctahedral {(VIVO)2FO6} units as the fundamental motif. In the case of 1, the layers are linked through {VIIIO6} octahedra, while for 2 the interlayer connectivity is provided by edge-sharing {(VIVO)2F2O6} units. Crystal data are 1 · 2H2O, CH10FN0.5O13P2V2.5, monoclinicC2/m,a= 18.425(4) Å,c= 8.954(2) Å, β = 93.69(2)0,V= 1221.1(4) Å3,Z= 4,Dcalc= 2.423 g cm-3; 2 · H2O, H4F2K2O13P2V3, triclinicPoverline1,a= 7.298(1) Å,b= 8.929(2) Å,c = 10.090(2) Å, α = 104.50(2)0, β = 100.39(2)0, δ = 92.13(2)0,V= 623.8(3) Å3,Z= 2,Dcalc= 2.891 g cm-3.

Comparison of Seven Chemical Pretreatments of Corn Straw for Improving Methane Yield by Anaerobic Digestion

PubMed Central

Song, Zilin; GaiheYang; Liu, Xiaofeng; Yan, Zhiying; Yuan, Yuexiang; Liao, Yinzhang

2014-01-01

Agriculture straw is considered a renewable resource that has the potential to contribute greatly to bioenergy supplies. Chemical pretreatment prior to anaerobic digestion can increase the anaerobic digestibility of agriculture straw. The present study investigated the effects of seven chemical pretreatments on the composition and methane yield of corn straw to assess their effectiveness of digestibility. Four acid reagents (H2SO4, HCl, H2O2, and CH3COOH) at concentrations of 1%, 2%, 3%, and 4% (w/w) and three alkaline reagents (NaOH, Ca(OH)2, and NH3·H2O) at concentrations of 4%, 6%, 8%, and 10% (w/w) were used for the pretreatments. All pretreatments were effective in the biodegradation of the lignocellulosic straw structure. The straw, pretreated with 3% H2O2 and 8% Ca(OH)2, acquired the highest methane yield of 216.7 and 206.6 mL CH4 g VS −1 in the acid and alkaline pretreatments, which are 115.4% and 105.3% greater than the untreated straw. H2O2 and Ca(OH)2 can be considered as the most favorable pretreatment methods for improving the methane yield of straw because of their effectiveness and low cost. PMID:24695485

Comparison of seven chemical pretreatments of corn straw for improving methane yield by anaerobic digestion.

PubMed

Song, Zilin; GaiheYang; Liu, Xiaofeng; Yan, Zhiying; Yuan, Yuexiang; Liao, Yinzhang

2014-01-01

Agriculture straw is considered a renewable resource that has the potential to contribute greatly to bioenergy supplies. Chemical pretreatment prior to anaerobic digestion can increase the anaerobic digestibility of agriculture straw. The present study investigated the effects of seven chemical pretreatments on the composition and methane yield of corn straw to assess their effectiveness of digestibility. Four acid reagents (H2SO4, HCl, H2O2, and CH3COOH) at concentrations of 1%, 2%, 3%, and 4% (w/w) and three alkaline reagents (NaOH, Ca(OH)2, and NH3·H2O) at concentrations of 4%, 6%, 8%, and 10% (w/w) were used for the pretreatments. All pretreatments were effective in the biodegradation of the lignocellulosic straw structure. The straw, pretreated with 3% H2O2 and 8% Ca(OH)2, acquired the highest methane yield of 216.7 and 206.6 mL CH4 g VS(-1) in the acid and alkaline pretreatments, which are 115.4% and 105.3% greater than the untreated straw. H2O2 and Ca(OH)2 can be considered as the most favorable pretreatment methods for improving the methane yield of straw because of their effectiveness and low cost.

Alteration of chemical behavior of L-ascorbic acid in combination with nickel sulfate at different pH solutions in vitro

PubMed Central

Maniyar, Shaheen A; Jargar, Jameel G; Das, Swastika N; Dhundasi, Salim A; Das, Kusal K

2012-01-01

Objective To evaluate the alteration of chemical behavior of L-ascorbic acid (vitamin C) with metal ion (nickel) at different pH solutions in vitro. Methods Spectra of pure aqueous solution of L-ascorbic acid (E mark) compound and NiSO4 (H2O) (sigma USA) were evaluated by UV visible spectrophotometer. Spectral analysis of L-ascorbic acid and nickel at various pH (2.0, 7.0, 7.4 and 8.6) at room temperature of 29 °C was recorded. In this special analysis, combined solution of L-ascorbic acid and nickel sulfate at different pH was also recorded. Results The result revealed that λmax (peak wavelength of spectra) of L-ascorbic acid at pH 2.0 was 289.0 nm whereas at neutral pH 7.0, λmax was 295.4 nm. In alkaline pH 8.6, λmax was 295.4 nm and at pH 7.4 the λmax of L-ascorbic acid remained the same as 295.4 nm. Nickel solution at acidic pH 2.0 was 394.5 nm, whereas at neutral pH 7.0 and pH 7.4 were the same as 394.5 nm. But at alkaline pH 8.6, λmax value of nickel sulfate became 392.0 nm. The combined solution of L-ascorbic acid and nickel sulfate (6 mg/mL each) at pH 2.0 showed 292.5 nm and 392.5 nm, respectively whereas at pH 7.0, L-ascorbic acid showed 296.5 nm and nickel sulfate showed 391.5 nm. At pH 7.4, L-ascorbic acid showed 297.0 nm and nickel sulfate showed 394.0 nm in the combined solution whereas at pH 8.6 (alkaline) L-ascorbic acid and nickel sulfate were showing 297.0 and 393.5 nm, respectively. Conclusions Results clearly indicate an altered chemical behavior of L-ascorbic acid either alone or in combination with nickel sulfate in vitro at different pH. Perhaps oxidation of L-ascorbic acid to L-dehydro ascorbic acid via the free radical (HSc*) generation from the reaction of H2ASc + Ni (II) is the cause of such alteration of λmax value of L-ascorbic acid in the presence of metal nickel. PMID:23569901

Structural diversity of four coordination polymers based on 5-nitro-1,2,3-benzenetricarboxylic acid (H3nbta): Solvothermal syntheses, structural characterizations and properties

NASA Astrophysics Data System (ADS)

Shi, Chenjie; Wang, Zikai; Chen, Yifan; Zhang, Xiaoyu; Zhao, Yue; Tao, Yuehong; Wu, Hua

2017-09-01

Four 3D coordination compounds, named [Cd3(nbta)2(bix)2(H2O)2]·H2O (1), Zn3(nbta)2(biim)3 (2), Zn6(nbta)4(btd)5 (3) and [Co3(nbta)2(bid)(H2O)8]·4H2O (4) (bix=1,4-bis(imidazole-1-ylmethyl)benzene, biim=1,1‧-(1,4-butanediyl)bis(imidazole), btd=1,10-bis(1,2,4-triazol-1-yl)decane, bid=1,10-bis(imidazole-1-yl)decane), and H3nbta=5-nitro-1,2,3-benzenetricarboxylic acid), have been synthesized by solvothermal methods and structurally characterized by X-ray diffraction studies. In compound 1, every nbta3- anion connects four CdII ions to give a 2D layer, and the layers are pillared by bix ligands to generate a 3D framework with a Schläfli symbol of (3·4·63·7)(4·64·8)(43·63)(34·42·66·76·88·92). For compound 2, every nbta3- anion connects three ZnII ions to give a 2D layer structure, the 2D layers are further connected into a facinating 3D framework by biim ligands with (3,4)-connected (3·6·7)(3·5·62·7·8)(3·52·6·8·9)(5·6·8·10·112) topology. In compound 3, the nbta3- anions are connected by ZnII ions to generate a 2D layer, and the layers are bridged by btd ligands to build a fascinating 3D framework with (4·6·7·8·92)(4·6·8·92·10)(4·93·102)(4·6·8·9·102)(4·6·7·8·9·10)(4·6·7·8·102)(42·6·7·8·9) topology. In compound 4, the nbta3- aions are connected by CoII ions into a 2D layer, the 2D layers are linked by bid ligands to generate a 3D 103 topological framework. Furthermore, the IR spectra, TGA, PXRD, elemental analyses, the solid-state luminescence of compounds 1-3 have been studied.

Trapping {BW12}2 tungstoborate: synthesis and crystal structure of hybrid [{(H2BW12O42)2O}{Mo6O6S6(OH)4(H2O)2}]14- anion.

PubMed

Korenev, V S; Abramov, P A; Vicent, C; Mainichev, D A; Floquet, S; Cadot, E; Sokolov, M N; Fedin, V P

2012-12-28

Reaction between monolacunary {BW(11)} tungstoborate and oxothiocationic building block, {Mo(2)O(2)S(2)}, results in the formation of a new polyoxothiometalate with a unique architecture in which two [H(2)BW(12)O(43)](9-) tungstoborate subunits are linked together with a hexamolybdate [Mo(V)(6)O(6)S(6)(OH)(4)(H(2)O)(2)](2+) bridge.

A molecular hybrid polyoxometalate-organometallic moieties and its relevance to supercapacitors in physiological electrolytes

NASA Astrophysics Data System (ADS)

Chinnathambi, Selvaraj; Ammam, Malika

2015-06-01

Supercapacitors operating in physiological electrolytes are of great relevance for both their environmentally friendly aspect as well as the possibility to be employed for powering implantable microelectronic devices using directly biological fluids as electrolytes. Polyoxometalate (POMs) have been proven to be useful for supercapacitors in acidic media. However, in neutral pH, POMs are usually not stable. One relevant alternative is to stabilize POMs by pairing them with organic moieties to form hybrids. In this study, we combined K6P2Mo18O62·12H2O (P2Mo18) with Ru(bpy)3Cl2.6H2O (Ru(bpy)). The synthesis was carried out with and without the mild reducing agent KI. The hybrids were characterized by CHN analysis, TEM, FT-IR, XRD, TGA and cyclic voltammetry. CHN elemental analysis revealed that one mole [P2Mo18O62]6- is paired with 3 mol [Ru(bpy)3]2+ to form [Ru(bpy)3]3PMo18O62·nH2O. With KI present, [P2Mo18O62]6- is linked to 3.33 mol to yield [Ru(bpy)3]3.33PMo18O62·mH2O. Excess of Ru(bpy) in [Ru(bpy)3]3.33PMo18O62·mH2O was further confirmed by TEM, FT-IR, XRD, TGA and cyclic voltammetry. In turn, hybrid composition is found to strongly influence the supercapacitor behavior. The hybrid rich in Ru(bpy) is found to perform better for supercapacitors in physiological electrolytes. 125 F g-1 and 68 F g-1 are the capacitance values obtained with [Ru(bpy)3]3.33PMo18O62·mH2O and [Ru(bpy)3]3PMo18O62·nH2O, respectively. In terms of specific energy densities, 3.5 Wh kg-1 and 2 Wh kg-1 were obtained for both hybrid simultaneously. The difference in supercapacitor performance between both hybrids is also noticed in impedance spectroscopy which showed that [Ru(bpy)3]3.33PMo18O62·mH2O has lower electron transfer resistance if compared to [Ru(bpy)3]3PMo18O62·nH2O. Finally, if compared of parent K6P2Mo18O62·12H2O, the stability of both hybrids is found to be highly improved.

4,4′-Bipyridinium bis(perchlorate)–4-aminobenzoic acid–4,4′-bipyridine–water (1/4/2/2)

PubMed Central

Meng, Qun-Hui; Han, Lu; Hou, Jian-Dong; Luo, Yi-Fan; Zeng, Rong-Hua

2009-01-01

In the structure of the title compound, C10H10N2 2+·2ClO4 −·4C7H7NO2·2C10H8N2·2H2O, the 4,4′-bipyridinium cation has a crystallographically imposed centre of symmetry. The cation is linked by N—H⋯N hydrogen bonds to adjacent 4,4′-bipyridine mol­ecules, which in turn inter­act via O—H⋯N hydrogen bonds with 4-amino­benzoic acid mol­ecules, forming chains running parallel to [30]. The chains are further connected into a three-dimensional network by N—H⋯O and O—H⋯O hydrogen-bonding inter­actions involving the perchlorate anion, the water mol­ecules and the 4-amino­benzoic acid mol­ecules. In addition, π–π stacking inter­actions with centroid–centroid distances ranging from 3.663 (6) to 3.695 (6) Å are present. The O atoms of the perchlorate anion are disordered over two sets of positions, with refined site occupancies of 0.724 (9) and 0.276 (9). PMID:21581593

An experimental and theoretical study of a hydrogen-bonded complex: O-phenylenediamine with 2,6-pyridinedicarboxylic acid

NASA Astrophysics Data System (ADS)

Ghasemi, Khaled; Rezvani, Ali Reza; Habibi-Khorassani, Sayyed Mostafa; Shahraki, Mehdi; Shokrollahi, Ardeshir; Moghimi, Abolghasem; Tamandani, Halimeh Kord; Gavahi, Sara

2015-11-01

The hydrogen-bonded complex, [(OPDH)+(dipicH)-.H2O], between o-phenylenediamine (OPD) and 2,6-pyridinedicarboxylic acid (dipicH2) has been characterized in water by the 1H, 13C NMR and IR spectroscopies. The crystal structure showed that the edge to face C-H⋯π and C-O⋯π stacking interactions between the dipicH2 and OPD rings play an extra significant role in the formation of the hydrogen-bonded complex and supported the H-bonding interactions. The proton transfer also investigated theoretically in gas phase and thermodynamic parameters such as ΔH‡, ΔG‡, ΔS‡ were calculated for this process. Moreover, intramolecular hydrogen-bonding interaction has been recognized by calculating the electron density ρ(r) and Laplacian ∇2ρ(r) at the bond critical point (BCP) using Atoms-In-Molecule (AIM) method and also the interaction between electron acceptor (σ*) of OH with the lone pair of the nitrogen atom as an electron donor using Natural Bond Orbital (NBO) analysis. In addition, the protonation constants of dipicH2 and OPD and the equilibrium constants for the dipic-OPD (1:1) proton transfer system were obtained by the potentiometric pH titration method using the Hyperquad 2008 program. The stoichiometry of the proton transfer species in the solution confirmed the solid state result.

pH-Dependent Antimicrobial Properties of Copper Oxide Nanoparticles in Staphylococcus aureus

PubMed Central

Hsueh, Yi-Huang; Tsai, Ping-Han; Lin, Kuen-Song

2017-01-01

The antimicrobial properties of CuO nanoparticles have been investigated, but the underlying mechanisms of toxicity remain the subject of debate. Here, we show that CuO nanoparticles exhibit significant toxicity at pH 5 against four different Staphylococcus aureus (S. aureus) strains, including Newman, SA113, USA300, and ATCC6538. At this pH, but not at pH 6 and 7, 5 mM CuO nanoparticles effectively caused reduction of SA113 and Newman cells and caused at least 2 log reduction, whereas 20 mM killed most strains but not USA300. At 5 mM, the nanoparticles were also found to dramatically decrease reductase activity in SA113, Newman, and ATCC6538 cells, but not USA300 cells. In addition, analysis of X-ray absorption near-edge structure and extended X-ray absorption fine structure confirmed that S. aureus cells exposed to CuO nanoparticles contain CuO, indicating that Cu2+ ions released from nanoparticles penetrate bacterial cells and are subsequently oxidized intracellularly to CuO at mildly acidic pH. The CuO nanoparticles were more soluble at pH 5 than at pH 6 and 7. Taken together, the data conclusively show that the toxicity of CuO nanoparticles in mildly acidic pH is caused by Cu2+ release, and that USA300 is more resistant to CuO nanoparticles (NPs) than the other three strains. PMID:28397766

Synthesis and structure of cesium complexes of nitrilotris(methylenephosphonic) acid [Cs-μ6-NH(CH2PO3)3H4] and [Cs2-μ10-NH(CH2PO3H)3] · H2O

NASA Astrophysics Data System (ADS)

Somov, N. V.; Chausov, F. F.; Zakirov, R. M.

2017-07-01

3D coordination polymers cesium nitrilotris(methylenephosphonate) and dicesium nitrilotris( methylenephosphonate) are synthesized and their crystal structure is determined. In the crystal of [Cs-μ6-NH(CH2PO3)3H4] (space group P, Z = 2), cesium atoms occupy two crystallographically inequivalent positions with c.n. = 10 and c.n. = 14. The phosphonate ligand plays the bridging function; its denticity is nine. The crystal packing consists of alternating layers of Cs atoms in different environments with layers of ligand molecules between them. A ligand is bound to three Cs atoms of one layer and three Cs atoms of another layer. In the crystal of [Cs2-μ10-NH(CH2PO3H)3] · H2O (space group P, Z = 2), the complex has a dimeric structure: the bridging phosphonate ligand coordinates Cs to form a three-dimensional Cs4O6 cluster. The denticity of the ligand is equal to nine; the coordination numbers of cesium atoms are seven and nine. Two-dimensional corrugated layers of Cs4O6 clusters lie in the (002) plane, and layers of ligand molecules are located between them. Each ligand molecule coordinates eight Cs atoms of one layer and two Cs atoms of the neighboring layer.

Identification of critical amino acids in the proximal C-terminal of TREK-2 K+ channel for activation by acidic pHi and ATP-dependent inhibition.

PubMed

Woo, Joohan; Jun, Young Keul; Zhang, Yin-Hua; Nam, Joo Hyun; Shin, Dong Hoon; Kim, Sung Joon

2018-02-01

TWIK-related two-pore domain K + channels (TREKs) are regulated by intracellular pH (pH i ) and Phosphatidylinositol 4,5-bisphosphate (PI(4,5)P 2 ). Previously, Glu 306 in proximal C-terminal (pCt) of mouse TREK-1 was identified as the pH i -sensing residue. The direction of PI(4,5)P 2 sensitivity is controversial, and we have recently shown that TREKs are inhibited by intracellular ATP via endogenous PI(4,5)P 2 formation. Here we investigate the anionic and cationic residues of pCt for the pH i and ATP-sensitivity in human TREK-2 (hTREK-2). In inside-out patch clamp recordings (I TREK-2,i-o ), acidic pH i -induced activation was absent in E332A and was partly attenuated in E335A. Neutralization of cationic Lys (K330A) also eliminated the acidic pH i sensitivity of I TREK-2,i-o . Unlike the inhibition of wild-type (WT) I TREK-2,i-o by intracellular ATP, neither E332A nor K330A was sensitive to ATP. Nevertheless, exogenous PI(4,5)P 2 (10 μM) abolished I TREK-2 i-o in all the above mutants as well as in WT, indicating unspecific inhibition by exogenous PI(4,5)P 2 . In whole-cell recordings of TREK-2 (I TREK-2,w-c ), K330A and E332A showed higher or fully active basal activity, showing attenuated or insignificant activation by 2-APB, arachidonic acid, or acidic pH e 6.9. I TREK-1,w-c of WT is largely suppressed by pH e 6.9, and the inhibition is slightly attenuated in K312A and E315A. The results show concerted roles of the oppositely charged Lys and Glu in pCt for the ATP-dependent low basal activity and pH i sensitivity.

Remediation of TCE-contaminated groundwater using acid/BOF slag enhanced chemical oxidation.

PubMed

Tsai, T T; Kao, C M; Wang, J Y

2011-04-01

The objective of this study was to evaluate the potential of applying acid/H(2)O(2)/basic oxygen furnace slag (BOF slag) and acid/S(2)O(8)(2-)/BOF slag systems to enhance the chemical oxidation of trichloroethylene (TCE)-contaminated groundwater. Results from the bench-scale study indicate that TCE oxidation via the Fenton-like oxidation process can be enhanced with the addition of BOF slag at low pH (pH=2-5.2) and neutral (pH=7.1) conditions. Because the BOF slag has iron abundant properties (14% of FeO and 6% of Fe(2)O(3)), it can be sustainably reused for the supplement of iron minerals during the Fenton-like or persulfate oxidation processes. Results indicate that higher TCE removal efficiency (84%) was obtained with the addition of inorganic acid for the activation of Fenton-like reaction compared with the experiments with organic acids addition (with efficiency of 10-15% lower) (BOF slag=10gL(-1); initial pH=5.2). This could be due to the fact that organic acids would compete with TCE for available oxidants. Results also indicate that the pH value had a linear correlation with the observed first-order decay constant of TCE, and thus, lower pH caused a higher TCE oxidation rate. Copyright © 2011 Elsevier Ltd. All rights reserved.

Extending the lanthanide-terephthalate system: Isolation of an unprecedented Tb(III)-based coordination polymer with high potential porosity and luminescence properties

NASA Astrophysics Data System (ADS)

Le Natur, François; Calvez, Guillaume; Freslon, Stéphane; Daiguebonne, Carole; Bernot, Kevin; Guillou, Olivier

2015-04-01

A novel coordination polymer with chemical formula {[Tb(bdc)1.5(H2O)]ṡ(DMF)(H2O)}∞ (1) has been synthesized by reaction between 1,4-benzene-dicarboxylic acid (H2bdc) and di-cationic hexanuclear entity [Tb6O(OH)8(NO3)6(H2O)12]2+ in an ethylene glycol (EG)/N,N-dimethylformamide (DMF) mixture. This compound has been obtained as single crystals by slow evaporation in air at room temperature. If the hexanuclear entity is destroyed during the reaction, the coordination polymer that is obtained is original and presents promising potential micro-porosity and luminescent properties. It crystallizes in the monoclinic system, space group C12/c1 (No. 15) with the cell parameters a = 23.7540(1) Å, b = 10.5390(4) Å, c = 19.7580(3) Å, β = 125.8100(1)° and Z = 8.

Metabolism of D-[1-3H]glucose, D-[2-3H]glucose, D-[5-3H]glucose, D-[6-3H]glucose and D-[U-14C]glucose by rat and human erythrocytes incubated in the presence of H2O or D2O.

PubMed

Conget, I; Malaisse, W J

1995-02-01

The present study investigates whether heavy water affects the efficiency of 3HOH production from D-[1-3H]glucose, D-[2-3H]glucose, D-[5-3H]glucose and D-[6-3H]glucose relative to the total generation of tritiated metabolites produced by either rat or human erythrocytes. The relative 3HOH yield was close to 95% with D-[5-3H]glucose, 72% with D-[2-3H]glucose, 22-32% with D-[1-3H]glucose, and only 12% with D-[6-3H]glucose. In the latter case, the comparison of the specific radioactivity of intracellular and extracellular acidic metabolites, expressed relative to that of 14C-labelled metabolites produced from D-[U-14C]glucose, indicated that the generation of 3HOH from D-[6-3H]glucose occurs at distal metabolic steps, such as the partial reversion of the pyruvate kinase reaction or the interconversion of pyruvate and L-alanine in the reaction catalysed by glutamate-pyruvate transaminase. As a rule, the substitution of H2O by D2O only caused minor to negligible changes in the relative 3HOH yield. This implies that the unexpectedly high deuteration of 13C-labelled D-glucose metabolites recently documented in erythrocytes exposed to D2O cannot be attributed to any major interference of heavy water with factors regulating both the deuteration and detritiation efficiency, such as the enzyme-to-enzyme tunnelling of specific glycolytic intermediates.

Hydrothermal syntheses, structures and characterizations of three one-dimensional polyoxomolybdates with 4,4'-dimethylenebiphenyl diphosphonic acid as bridge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang Huishuang; Fu Ruibiao; Zhang Jianjun

2005-05-15

Three heterometallic 1-D polymers, [{l_brace}Ni(1,10-phen){sub 2}(H{sub 2}O){r_brace}{sub 2} {l_brace}(Mo{sub 5}O{sub 15})(4,4'-dbp){r_brace}.(5.75H{sub 2}O)] (4,4'-dbp=O{sub 3}PCH{sub 2}C{sub 6}H{sub 4}C{sub 6}H{sub 4}CH{sub 2}PO{sub 3}) (1), [{l_brace}Co(1,10-phen){sub 2}(H{sub 2}O){r_brace}{sub 2} {l_brace}(Mo{sub 5}O{sub 15})(4,4'-dbp){r_brace}.(5.5H{sub 2}O)] (2) and [{l_brace}Ni(2,2'-bpy){sub 3}{r_brace}{l_brace}Ni(2,2'-bpy){sub 2}(H{sub 2}O){r_brace} {l_brace}(Mo{sub 5}O{sub 15})(4,4'-dbp){r_brace}.(4.75H{sub 2}O)] (3), have been synthesized under hydrothermal conditions. Their structures were determined by single crystal X-ray diffraction. The 1-D chains is constructed of [Mo{sub 5}O{sub 15}(4,4'-dbp)]{sup 4-} units, which are further decorated and charge compensated by [M(1,10-phen){sub 2}] (M=Ni, Co) or [Ni(2,2'-bpy){sub 2}] subunits. The thermogravimetric analyses and magnetic properties of 1 and 2 were studied.

Document Image Compression and Analysis

DTIC Science & Technology

1997-04-01

F3 ’Q>F6BUKXYU󈨐&2:38’CZ3 O ’[5>:H3Z3 O > F3 /3 O 󈧵LA\\+󈨊Ś...H2$6SH0A#BU+’K3 O >3V2:@BCg’�%8h^’U�U+���𔄁%8’�6BH’C N4O RH O 2+H7H#&%<@B󈨍 N ’�󈨐�> 9&%2$382:3E;9B’�>F6BU�>�H�>F6BURU&> F3 ’D9B> F3 ...38#&%’>F6BUD6&2$3Q6&2$RCg’>F6SU�C O 2$#&0RUI3 O 𔄁%8𔃿=2:%8’W@B’ H2:6BCgRU𔄁%8’_U N ŗ ODO "! O

Biodiesel production from non-edible Silybum marianum oil using heterogeneous solid base catalyst under ultrasonication.

PubMed

Takase, Mohammed; Chen, Yao; Liu, Hongyang; Zhao, Ting; Yang, Liuqing; Wu, Xiangyang

2014-09-01

The aim of this study is to investigate modified TiO2 doped with C4H4O6HK as heterogeneous solid base catalyst for transesterification of non-edible, Silybum marianum oil to biodiesel using methanol under ultrasonication. Upon screening the catalytic performance of modified TiO2 doped with different K-compounds, 0.7 C4H4O6HK doped on TiO2 was selected. The preparation of the catalyst was done using incipient wetness impregnation method. Having doped modified TiO2 with C4H4O6HK, followed by impregnation, drying and calcination at 600 °C for 6 h, the catalyst was characterized by XRD, FTIR, SEM, BET, TGA, UV and the Hammett indicators. The yield of the biodiesel was proportional to the catalyst basicity. The catalyst had granular and porous structures with high basicity and superior performance. Combined conditions of 16:1 molar ratio of methanol to oil, 5 wt.% catalyst amount, 60 °C reaction temperature and 30 min reaction time was enough for maximum yield of 90.1%. The catalyst maintained sustained activity after five cycles of use. The oxidative stability which was the main problem of the biodiesel was improved from 2.0 h to 3.2h after 30 days using ascorbic acid as antioxidant. The other properties including the flash point, cetane number and the cold flow ones were however, comparable to international standards. The study indicated that Ti-0.7-600-6 is an efficient, economical and environmentally, friendly catalyst under ultrasonication for producing biodiesel from S. marianum oil with a substantial yield. Copyright © 2014 Elsevier B.V. All rights reserved.

The precipitation of magnesium potassium phosphate hexahydrate for P and K recovery from synthetic urine.

PubMed

Xu, Kangning; Li, Jiyun; Zheng, Min; Zhang, Chi; Xie, Tao; Wang, Chengwen

2015-09-01

Nutrients recovery from urine to close the nutrient loop is one of the most attractive benefits of source separation in wastewater management. The current study presents an investigation of the thermodynamic modeling of the recovery of P and K from synthetic urine via the precipitation of magnesium potassium phosphate hexahydrate (MPP). Experimental results show that maximum recovery efficiencies of P and K reached 99% and 33%, respectively, when the precipitation process was initiated only through adding dissolvable Mg compound source. pH level and molar ratio of Mg:P were key factors determining the nutrient recovery efficiencies. Precipitation equilibrium of MPP and magnesium sodium phosphate heptahydrate (MSP) was confirmed via precipitates analysis using a Scanning Electron Microscope/Energy Dispersive Spectrometer and an X-ray Diffractometer. Then, the standard solubility products of MPP and MSP in the synthetic urine were estimated to be 10(-12.2 ± 0.0.253) and 10(-11.6 ± 0.253), respectively. The thermodynamic model formulated on chemical software PHREEQC could well fit the experimental results via comparing the simulated and measured concentrations of K and P in equilibrium. Precipitation potentials of three struvite-type compounds were calculated through thermodynamic modeling. Magnesium ammonium phosphate hexahydrate (MAP) has a much higher tendency to precipitate than MPP and MSP in normal urine while MSP was the main inhibitor of MPP in ammonium-removed urine. To optimize the K recovery, ammonium should be removed prior as much as possible and an alternative alkaline compound should be explored for pH adjustment rather than NaOH. Copyright © 2015 Elsevier Ltd. All rights reserved.

Crystal structure, vibrational and DFT simulation studies of melaminium dihydrogen phosphite monohydrate

NASA Astrophysics Data System (ADS)

Arjunan, V.; Kalaivani, M.; Marchewka, M. K.; Mohan, S.

2013-08-01

The crystal structure investigations of melamine with phosphorous acid, namely melaminium dihydrogenphosphite monohydrate (C3N6H7·H2PO3·H2O) have been investigated by means of single crystal X-ray diffraction method. The title compound crystallizes in monoclinic crystal system, and the space group is P21/c with a = 10.069 Å, b = 21.592 Å, c = 12.409 Å and Z = 12. The vibrational assignments and analysis of melaminium dihydrogen phosphite monohydrate have also been performed by FTIR, FT-Raman and far-infrared spectral studies. The quantum chemical simulations were performed with DFT (B3LYP) method using 6-31G**, cc-pVTZ, and 6-311++G** basis sets to determine the energy, structural, thermodynamic parameters and vibrational frequencies of melaminium dihydrogen phosphite monohydrate. The hydrogen atom from phosphorous acid was transferred to the melamine molecule giving the singly protonated melaminium cation. The ability of ions to form spontaneous three-dimensional structure through weak Osbnd H···O and Nsbnd H···O hydrogen bonds shows notable vibrational effects.

Improved Catalytic Activity and Stability of a Palladium Pincer Complex by Incorporation into a Metal-Organic Framework.

PubMed

Burgess, Samantha A; Kassie, Abebu; Baranowski, Sarah A; Fritzsching, Keith J; Schmidt-Rohr, Klaus; Brown, Craig M; Wade, Casey R

2016-02-17

A porous metal-organic framework Zr6O4(OH)4(L-PdX)3 (1-X) has been constructed from Pd diphosphinite pincer complexes ([L-PdX](4-) = [(2,6-(OPAr2)2C6H3)PdX](4-), Ar = p-C6H4CO2(-), X = Cl, I). Reaction of 1-X with PhI(O2CCF3)2 facilitates I(-)/CF3CO2(-) ligand exchange to generate 1-TFA and I2 as a soluble byproduct. 1-TFA is an active and recyclable catalyst for transfer hydrogenation of benzaldehydes using formic acid as a hydrogen source. In contrast, the homogeneous analogue (t)Bu(L-PdTFA) is an ineffective catalyst owing to decomposition under the catalytic conditions, highlighting the beneficial effects of immobilization.

Synthesis, characterization, electrochemical investigation and antioxidant activities of a new hybrid cyclohexaphosphate: Cu1.5Li(C2H10N2)P6O18·7H2O

NASA Astrophysics Data System (ADS)

Sleymi, Samira; Lahbib, Karima; Rahmouni, Nihed; Rzaigui, Mohamed; Besbes-Hentati, Salma; Abid, Sonia

2017-09-01

A new organic-inorganic hybrid transition metal phosphate, Cu1.5Li(C2H10N2)P6O18·7H2O, has been prepared and characterized by X-ray diffraction, spectroscopy (infrared, Raman, diffuse reflectance and UV-Vis) and thermal analysis (TG). In addition, its electrochemical behaviors, as well as its antioxidant and antibacterial activities, have been investigated. Its structure is built up by the alternate linkages between copper and phosphate polyhedra, forming puckered layers with intersecting 12-membered rings, in which the ethylenediammonium cations reside. This compound is the first framework structure constructed from cyclohexaphosphates and three distinct copper cations. Cyclic voltammetry study in an acetonitrile solution reveals the facile anodic oxidation of its organic part on a platinum disk and a progressive growing of a thin film, though the repetitive cycling of potential. The title compound was tested for its in vitro antioxidant activities by 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2‧-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), Ferrous chelating ability (FIC) and Ferric Reducing Power (FRP) methods. The antioxidant activity of Cu1.5Li(C2H10N2)P6O18·7H2O was analyzed simultaneously with its antibacterial capacity against Escherichia coli, Salmonella typhimurium, Staphylococus aureus, Enterococcus feacium, Streptococcus agalactiae and Candida albicans. The tested compound showed significant antioxidant activities with low antibacterial properties.

C-C cross-coupling reactions of O6-alkyl-2-haloinosine derivatives and a one-pot cross-coupling/O6-deprotection procedure.

PubMed

Gurram, Venkateshwarlu; Pottabathini, Narender; Garlapati, Ramesh; Chaudhary, Avinash B; Patro, Balaram; Lakshman, Mahesh K

2012-08-01

Reaction conditions for the CC cross-coupling of O(6)-alkyl-2-bromo- and 2-chloroinosine derivatives with aryl-, hetaryl-, and alkylboronic acids were studied. Optimization experiments with silyl-protected 2-bromo-O(6)-methylinosine led to the identification of [PdCl(2)(dcpf)]/K(3)PO(4) in 1,4-dioxane as the best conditions for these reactions (dcpf=1,1'-bis(dicyclohexylphosphino)ferrocene). Attempted O(6)-demethylation, as well as the replacement of the C-6 methoxy group by amines, was unsuccessful, which led to the consideration of Pd-cleavable groups such that C-C cross-coupling and O(6)-deprotection could be accomplished in a single step. Thus, inosine 2-chloro-O(6)-allylinosine was chosen as the substrate and, after re-evaluation of the cross-coupling conditions with 2-chloro-O(6)-methylinosine as a model substrate, one-step C-C cross-coupling/deprotection reactions were performed with the O(6)-allyl analogue. These reactions are the first such examples of a one-pot procedure for the modification and deprotection of purine nucleosides under C-C cross-coupling conditions. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Low-temperature, high yield synthesis, and convenient isolation of the high-electron-density cluster compound Ta6Br14.8H2O for use in biomacromolecular crystallographic phase determination.

PubMed

Hay, Daniel N T; Messerle, Louis

2002-09-01

Reduction of TaBr(5) with Ga in the presence of KBr in a sealed borosilicate ampule at 400 degrees, followed by aqueous Soxhlet extraction and addition of stannous bromide and hydrobromic acid to the extract, yielded Ta(6)Br(14).8H(2)O in 80-84% yield. The new procedure provides a convenient, low temperature, high yield route to the synthesis of the title compound from inexpensive precursors.

Novel metal(II) coordination polymers based on N,N'-bis-(4-pyridyl)phthalamide as supercapacitor electrode materials in an aqueous electrolyte.

PubMed

Gong, Yun; Li, Jian; Jiang, Peng-Gang; Li, Qing-Fang; Lin, Jian-Hua

2013-02-07

Based on the redox-active L (N,N'-bis-(4-pyridyl)phthalamide) ligand, two porous MOFs formulated as Zn(6)(BPC)(6)(L)(3)·9DMF (H(2)BPC = 4,4'-biphenyldicarboxylic acid) (1) and Cd(2)(TDC)(2)(L)(2)·4H(2)O (H(2)TDC = 2,5-thiophenedicarboxylic acid) (2) were synthesized and structurally characterized by single-crystal X-ray diffractions. Complex 1 features a uninodal 5-connected 3-fold interpenetrated 3D framework with {4(6).6(4)}-bnn hexagonal BN topology. Complex 2 displays a uninodal 6-connected 2-fold interpenetrated 3D framework with {4(12).6(3)}-pcu topology. When complexes 1 and 2 are used as supercapacitor electrode materials, they can provide a large voltage window as high as 2.6 V in an aqueous electrolyte, and their specific capacitances are much more than the value for the bare carbon glassy electrode. It is observed that the more the current density, the less the specific capacitance for the two kinds of supercapacitor electrode materials. The two complexes show different thermal stabilities, UV absorption and photoluminescence properties.

A three-dimensional coordination polymer based on 1,2,3-triazole-4,5-dicarboxylic acid (H{sub 3}tda): ([Cd{sub 12}(tda){sub 8}(H{sub 2}O){sub 11}] · (H{sub 2}O)6.25){sub n}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Xin-Hui, E-mail: iamxhzhou@njupt.edu.cn; Chen, Qiang

The title coordination polymer ([Cd{sub 12}(tda){sub 8}(H{sub 2}O){sub 11}] · (H{sub 2}O){sub 6.25}){sub n} (H{sub 3}tda = 1,2,3-triazole-4,5-dicarboxylic acid), has been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction. Complex crystallizes in orthorhombic sp. gr. Pmn2{sub 1} with Z = 4. The Cd{sub 2} unit doublebridged by one carboxylate oxygen atom and two neighboring nitrogen atoms from the tda{sup 3–} ligands are linked by the tda{sup 3–}ligands to lead to the 2D (4,4) network in the ac plane. The almost coplanar Cd{sub 2}(μ{sub 5}-tda){sub 2} unit comprised of two Cd ions double-bridged by two tda{sup 3–} ligands through themore » neighboring nitrogen atoms is connected with the other four Cd{sub 2}(μ{sub 5}-tda){sub 2} units form the undulating 2D network in the ac plane. The (4,4) networks and undulating 2D networks are alternatively connected along the b axis by the tda{sup 3–} ligands coordinating to the Cd ions to form the 3D framework.« less

Preparation, structure and luminescent characterization of a series of metal-organic frameworks based on flexible ligands with nitrogen heterocycles and carboxyl

NASA Astrophysics Data System (ADS)

Dai, Hai-yu; Tang, Yu-yuan; Wang, Cui-juan; Chen, Shuang; Tong, Yan; Zhang, Zhi-Bing

2017-12-01

Seven new compounds, [Zn(pypymba)2]n(1), [Co(pypymba)2]n(2), [Cd(pypymba)2]n(3), [Cd(Hpypymba)Cl2]n(4), {[Cd(pypymba)Cl]·C2H5OH·H2O}n(5), [Cd(pypyaa)Cl]n(6), {[Cd2(pyznpy)2Cl2H2O]·H2O}n(7) [Hpypymba = 4-((3-(pyrazin-2-yl)-1H-pyrazol-1-yl)methyl)benzoic acid, Hpyznpy = 4-((3-(pyridin-2-yl)-1H-pyrazol-1-yl)methyl)benzoic acid, Hpypyaa = 2-(3-pyridin-2-yl)-1H-pyrazol-1-yl)acetic acid], were hydrothermally synthesized by tuning the metal ion's species, counter anions, solvents and pH values and characterized by routine methods: XRD, elemental analysis, fluorescence properties analysis, TGA and crystal structure analysis and single-crystal X-ray crystallography. The main structures of the compounds 1, 2, and 3 are extended to similar 3D structures by C-H…N, C-H…O hydrogen bonds and π…π stacking under the same synthesis method. Each Cd(II) node of compound 4 has four chlorine bridges (two pairs of double chlorine); Each Cd(II) node of compounds 5, 6 has two chlorine bridges (a pair of double chlorine bridges), while their spatial structures are expanded in different ways. Compound 7 also contains chlorine atoms, but does not contain chlorine bridged structures. The luminescent properties of compound 7 and the ones immersed in various kinds of organic compounds and nitrate@EtOH solutions have been investigated. Importantly, 7 shows highly sensitive response to nitrobenzene and Fe3+ through luminescence quenching effects, making it a promising luminescent sensor for nitrobenzene and Fe3+.

Seven 3d-4f coordination polymers of macrocyclic oxamide with polycarboxylates: Syntheses, crystal structures and magnetic properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xin, Na; Key Laboratory of Inorganic-Organic Hybrid Functional Material Chemistry, Ministry of Education; Tianjin Key Laboratory of Structure and Performance for Functional Molecules

2016-11-15

Seven new 3d–4f heterometallic coordination polymers, [Ln(CuL){sub 2}(Hbtca)(btca)(H{sub 2}O)]·2H{sub 2}O (Ln = Tb{sup III}1, Pr{sup III}2, Sm{sup III}3, Eu{sup III}4, Yb{sup III}5), [Nd(NiL)(nip)(Rnip)]·0·25H{sub 2}O·0.25CH{sub 3}OH (R= 0.6CH{sub 3}, 0.4H) 6 and [Nd{sub 2}(NiL)(nip){sub 3}(H{sub 2}O)]·2H{sub 2}O 7(CuL or NiL, H{sub 2}L = 2, 3-dioxo-5, 6, 14, 15-dibenzo-1, 4, 8, 12-tetraazacyclo-pentadeca-7, 13-dien; H{sub 2}btca = benzotriazole-5-carboxylic acid; H{sub 2}nip = 5-nitroisophthalic acid) have been synthesized by a solvothermal method and characterized by single-crystal X-ray diffraction. Complexes 1–5 exhibit a double-strand meso-helical chain structures formed by [Ln{sup III}Cu{sup II}{sub 2}] units via the oxamide and benzotriazole-5-carboxylate bridges, while complex 6 exhibits amore » four-strand meso-helical chain formed by NdNi unit via the oxamide and 5-nitroisophthalate bridges. Complex 7 consists of a 2D layer framework formed by four-strand meso-helical chain via the nip{sup 2−} bridges. Moreover, the magnetic properties of them were investigated, and the best-fit analysis of χ{sub M}T versus T show that the anisotropic contribution of Ln(III) ions (arising from the spin-orbit coupling or the crystal field perturbation) dominates (weak exchange limit) in these complexes(for 3, λ = 214.6 cm{sup −1}, zj’ = −0.33 cm{sup −1}, g{sub av} = 1.94; for 5, Δ = 6.98 cm{sup −1}, zj’ = 1.53 cm{sup −1}, g{sub av} = 1.85). - Graphical-abstract: Seven novel oxamido-bridged 3d-4f heterometallic coordination polymers with benzotriazole-5-carboxylate or 5-nitroisophthalate co-ligands under solvothermal reaction conditions. Polymers 1–7 hold 1D or 2D framework structure, viz., double-strand meso-helical chain of 1–5, four-strand meso-helical chain of 6, and 2D net of 7 consisting of four-strand meso-helical chain. Moreover, the temperature dependences of magnetic susceptibilities of compounds 1–7 were also studied.« less

Cocrystals of a 1,2,4-thiadiazole-based potent neuroprotector with gallic acid: solubility, thermodynamic stability relationships and formation pathways.

PubMed

Surov, Artem O; Churakov, Andrei V; Proshin, Alexey N; Dai, Xia-Lin; Lu, Tongbu; Perlovich, German L

2018-05-30

Three distinct solid forms, namely anhydrous cocrystals with 2 : 1 and 1 : 1 drug/acid ratios ([TDZ : GA] (2 : 1), [TDZ : GA] (1 : 1)), and a hydrated one having 1 : 1 : 1 drug/acid/water stoichiometry ([TDZ : GA : H2O] (1 : 1 : 1)), have been formed by cocrystallization of the biologically active 1,2,4-thiadiazole derivative (TDZ) with gallic acid (GA). The thermodynamic stability relationships between the cocrystals were rationalized in terms of Gibbs energies of the formation reactions and further verified by performing a set of competitive and exchange mechanochemical reactions. Interestingly, competitive grinding in the presence of the structurally related vanillic acid led to the formation of a new polymorphic form of the [TDZ : Vanillic acid] (1 : 1) cocrystal, which was promoted by gallic acid. The mechanochemical method was also applied to elucidate the alternative pathways of the [TDZ : GA : H2O] (1 : 1 : 1) cocrystal formation. Direct cocrystallization of TDZ with GA monohydrate was found to proceed much faster than the reaction of TDZ and anhydrous GA in the presence of an acetonitrile/water mixture, which may indicate the presence of a transitional stage. According to dissolution studies, the [TDZ : GA : H2O] (1 : 1 : 1) cocrystal was ca. 6.6 times more soluble than the parent 1,2,4-thiadiazole at pH 2.0 and 25.0 °C. The apparent two-step dehydration behavior of the [TDZ : GA : H2O] (1 : 1 : 1) cocrystal monohydrate was clarified by analyzing the intermolecular interactions of water molecules with the crystalline environment derived from solid state DFT calculations.

Nucleic acid component analogues: synthesis of 2'-deoxynucleosides from 5-substituted-4-hydroxy-6(1H)-pyrimidinones.

PubMed

Khattab, Ahmed F; Abdel Megied, Ahmed E S; Pedersen, Erik B

2003-01-01

Condensation of the silylated pyrimidines 5a-c with methyl 2-deoxy-3,5-di-O-toluoyl-D-pentofuranoside 6, using trimethylsilyltriflate as catalyst gave anomeric mixtures of 2'-deoxynucleosides 7a-c, the pure alpha- and beta-anomers were separated and deprotected with sodium methoxide in methanol to give 1-(2'-deoxy-alpha-D-pentafuranosyl)-4-hydroxy-5-substituted-6(1H)-pyrimidinones 10a,b and 13a and their corresponding beta-anomers 11a,b and 13b.

Coordination Polymers Derived from Non-Steroidal Anti-Inflammatory Drugs for Cell Imaging and Drug Delivery.

PubMed

Paul, Mithun; Dastidar, Parthasarathi

2016-01-18

A new series of Mn(II) coordination polymers, namely, [{Mn(L)(H2 O)2 }⋅2 Nap]∞ (CP1), [{Mn(L)(Ibu)2 (H2 O)2 }]∞ (CP2), [{Mn(L)(Flr)2 (H2 O)2 }]∞ (CP3), [{Mn(L)(Ind)2 (H2 O)2 }⋅H2 O]∞ (CP4), [{Mn2 (L)2 (μ-Flu)4 (H2 O)}⋅L]∞ (CP5), [{Mn2 (L)2 (μ-Tol)4 (H2 O)2 }]∞ (CP6) and [{Mn2 (L)2 (μ-Mef)4 (H2 O)2 }]∞ (CP7) (Nap=naproxen, Ibu=ibuprofen, Flr=flurbiprofen, Ind=indometacin, Flu=flufenamic acid, Tol=tolfenamic acid and Mef=mefenamic acid) derived from various non-steroidal anti-inflammatory drugs (NSAIDs) and the organic linker 1,2-bis(4-pyridyl)ethylene (L) have been synthesized with the aim of being used for cell imaging and drug delivery. Single-crystal X-ray diffraction (SXRD) studies revealed that the NSAID molecules were part of the coordination polymeric network either through coordination to the metal center (in the majority of the cases) or through hydrogen bonding. Remarkably, all the Mn(II) coordination polymers were found to be soluble in DMSO, thereby making them particularly suitable for the desired biological applications. Two of the coordination polymers (namely, CP1 and CP3) reported herein, were found to be photoluminescent both in the solid as well as in the solution state. Subsequent experiments (namely, MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide), and PGE2 (prostaglandin E2 ) assays) established their biocompatibility and anti-inflammatory response. In vitro studies by using a macrophage cell line (i.e., RAW 264.7) revealed that both CP1 and CP3 were excellent cell imaging agents. Finally, biodegradability studies under simulated physiological conditions in phosphate-buffered saline (PBS) at pH 7.6 showed that slow and sustained release of the corresponding NSAID was indeed possible from both CP1 and CP3. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

QTAIM charge density study of natural cinnamic acids

NASA Astrophysics Data System (ADS)

González Moa, María J.; Mandado, Marcos; Mosquera, Ricardo A.

2006-06-01

B3LYP/6-311++G(2d,2p) 6d ionization potentials and O-H bond dissociation energies of natural cinnamic acids are consistent with an important antioxidant activity. The QTAIM analysis indicates that: (i) the benzene ring and the propenoic acid fragment of cinnamic acids behave as independent π systems; (ii) the ionization process consists in a loss of nearly 1 a.u. of π electron density by the atoms involved in HOMO accompanied by a reorganization of σ electron density that is mostly provided by the remaining atoms.

Benzene and toluene influence with or without nitrogen dioxide on inorganic pigments of works of art—Part II

NASA Astrophysics Data System (ADS)

Agelakopoulou, T.; Bassiotis, I.; Metaxa, E.; Roubani-Kalantzopoulou, F.

Air pollution has a great impact on the social and economic aspects all over the world. In order to account the human interaction with the atmospheric environment, a suitable scientific basis is needed. That is why six physicochemical quantities have been determined in a previous work for each one heterogeneous system between organic volatile pollutants and oxide-pigments of works of art. This investigation is extended in order to determine experimentally five new ones. Thus, a more precise contribution to the elucidation of the mechanism of the deterioration of various works of art in museums is achieved. These physicochemical quantities are: (1) local adsorption energies, (2) local monolayer capacities, (3) local adsorption isotherms, (4) density probability function, and (5) pollutant concentration on the oxide-pigment at equilibrium. All these adsorption parameters mentioned above have been calculated as a function of experimental time for the systems: C 6H 6/TiO 2, C 6H 6/NO 2/TiO 2, C 6H 6/Cr 2O 3, C 6H 6/NO 2/Cr 2O 3, C 6H 5CH 3/TiO 2, C 6H 5CH 3/NO 2/TiO 2, C 6H 5CH 3/Cr 2O 3, C 6H 5CH 3/NO 2/Cr 2O 3, C 6H 6/PbO, C 6H 6/NO 2/PbO, C 6H 5CH 3/PbO, and C 6H 5CH 3/NO 2/PbO for the first time. Thus, in this work we shall stress the recent new aspect of Reversed Flow-(Inverse) Gas Chromatography (RF-GC or RF-IGC), i.e. the time-resolved chromatography related to the evaluation of some important adsorption parameters. Gas Chromatography is a promising meeting place of surface science and atmospheric chemistry.

Seven new Zn(II)/Cd(II) coordination polymers with 2-(hydroxymethyl)-1H-benzo[d]imidazole-5-carboxylic acid: Synthesis, structures and properties

NASA Astrophysics Data System (ADS)

Wang, Xin-Fang; Zhou, Sheng-Bin; Du, Ceng-Ceng; Wang, Duo-Zhi; Jia, Dianzeng

2017-08-01

Using a new simi-rigid multitopic ligand 2-(hydroxymethyl)-1H-benzo[d]imidazole-5-carboxylic acid (H2L), seven new coordination polymers [Zn3(L)2(μ2-OH)2]n (1), {[Zn2(HL)2(H2O)2]·SiF6}n (2), [Zn(HL)(SCN)]n (3), {[Zn2(HL)2(SO4)]·(4,4‧-bpy)}n (4) [4,4‧-bpy =4,4‧-bipyridine], {[Zn(HL)2]·2H2O}n (5), {[Cd(HL)2]·2H2O}n (6) and [Cd2(HL)2(H2O)2(SO4)]n (7) have been successfully obtained from H2L ligand under solvothermal conditions and structurally characterized by single-crystal X-ray diffraction, elemental analysis, thermogravimetric analysis, powder X-ray diffraction and IR spectroscopy. In addition, UV-vis diffuse-reflectance spectra demonstrate wide band gaps. Complex 1 features a 3D topological net of {412·63} with the stoichiometry (6-c), contains 1D channels with the accessible solvent volume of 42.1%. 3, 4, 5 and 6 have a 1D chain structure, 5 and 6 further assemble to form 2D sheet and 3D supramolecular frameworks by hydrogen-bonding interactions, respectively. Complexes 2 and 7 possess a 2D layered structure, and the 2D supramolecular network of 2 can be rationalized to be four-connected {44·62} topological sql network with the dinuclear units, while 7 shows a 3-nodal 2D net with a point symbol of {63}. Moreover, the fluorescent emission, fluorescence lifetimes of 1-7 have been investigated and discussed. Interesting enough, complex 1 showed high efficiency for catalyzing the Knoevenagel condensation reaction between 4-substituted aromatic aldehydes and malononitrile as selective heterogeneous catalyst. The CPs combining catalytic and fluorescent properties could further meet the requirement as a multifunctional material. Seven new Zn(II)/Cd(II) coordination polymers with simi-rigid multitopic ligand, [(2-(hydroxymethyl)-1H-benzo[d]imidazole-5-carboxylic acid) (H2L)] have been successfully obtained and structurally characterized by single-crystal X-ray diffraction, elemental analysis, thermogravimetric analysis, powder X-ray diffraction and IR spectroscopy. All the complexes are air stable at room. In addition, the fluorescent emission, fluorescence lifetime and UV-vis diffuse-reflectance spectra of 1-7 and H2L have been investigated and discussed. Furthermore, we studied the Knoevenagel condensation reaction between 4-substituted aromatic aldehydes and malononitrile by activated 1a as selective heterogeneous catalyst.

Tuning different kinds of entangled metal-organic frameworks by modifying the spacer group of aliphatic dicarboxylate ligands and the reactant ratio.

PubMed

Yang, Jin-Xia; Zhai, Ji-Quan; Zhang, Xin; Qin, Ye-Yan; Yao, Yuan-Gen

2016-01-14

Taking advantage of the conformational flexibility of the bpp ligand and aliphatic dicarboxylic acids, six interesting entangled coordination polymers, {[Cd(fum)(bpp)(H2O)]·(H2O)}n (), {[Cd(fum)(bpp)2]·(H2O)5}n (), {[Cd2(suc)1.5(bpp)2(NO3)(H2O)2]·6H2O}n (), {[Cd(suc)(bpp)2]·(H2O)1.5}n (), {[Cd2(glu)2(bpp)3]·10H2O}n (), and {Cd(adp)(bpp)(H2O)}n () have been prepared and structurally characterized (bpp = 1,3-bi(4-pyridyl)propane, fum = fumaric, suc = succinate, glu = glutaric, adp = adipic). Compounds and are comprised of undulated 2D 4(4)-sql networks. In the structure of compound , two identical undulated layers are parallelly interpenetrated with each other to give a 2D → 2D interpenetrating framework. For , the dangling arms projected from 2D layers are intercalated into the neighboring sheets, producing a 2D → 3D polythreading framework. Compound shows a rare example of a 2D self-penetrating framework with a (3,4)-connected (4(2)·6(3)·8)(4(2)·6) topology. Compound presents an unusual 2D self-threading network with a novel 4-connected {4(2)·6(3)·8} topology. Compound displays a 3D self-penetrating system based on a 2D → 3D parallel polycatenation array. Compound exhibits an unprecedented 3D self-penetrating structure having both 1D + 1D → 1D polycatenation and 3D + 3D → 3D interpenetration characteristics. A comparison of these six compounds demonstrates that both the different spacer lengths of the aliphatic dicarboxylates and reactant ratios appear to play a significant role in the assembly of entangled frameworks. In addition, thermal stabilities and photoluminescence properties of have been examined in the solid state at room temperature.

LC-mS analysis of human urine specimens for 2-oxo-3-hydroxy LSD: method validation for potential interferants and stability study of 2-oxo-3-hydroxy LSD under various storage conditions.

PubMed

Klette, Kevin L; Horn, Carl K; Stout, Peter R; Anderson, Cynthia J

2002-01-01

2-Oxo-3-hydroxy lysergic acid diethylamide (O-H-LSD), a major LSD metabolite, has previously been demonstrated to be a superior marker for identifying LSD use compared with the parent drug, LSD. Specifically, O-H-LSD analyzed using liquid chromatography-mass spectrometry has been reported to be present in urine at concentrations 16 to 43 times greater than LSD. To further support forensic application of this procedure, the specificity of the assay was assessed using compounds that have structural and chemical properties similar to O-H-LSD, common over-the-counter products, prescription drugs and some of their metabolites, and other drugs of abuse. Of the wide range of compounds studied, none were found to interfere with the detection of O-H-LSD or the internal standard 2-oxo-3-hydroxy lysergic acid methyl propylamide. The stability of O-H-LSD was investigated from 0 to 9 days at various temperatures, pH conditions, and exposures to fluorescent light. Additionally, the effect of long-term frozen storage and pH was investigated from 0 to 60 days. There was no significant loss of O-H-LSD under both refrigerated and frozen conditions within the normal human physiological pH range of urine (4.6-8.4). However, significant loss of O-H-LSD was observed in samples prepared at pH 4.6-8.4 and stored at room temperature or higher (24-50 degrees C).

High-valent manganese–oxo valence tautomers and the influence of Lewis/Brönsted acids on C–H bond cleavage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baglia, Regina A.; Krest, Courtney M.; Yang, Tzuhsiung

The addition of Lewis or Brönsted acids (LA = Zn(OTf) 2, B(C 6F 5) 3, HBAr F, TFA) to the high-valent manganese–oxo complex Mn V(O)(TBP 8Cz) results in the stabilization of a valence tautomer Mn IV(O-LA)(TBP 8Cz •+). The Zn II and B(C 6F 5) 3 complexes were characterized by manganese K-edge X-ray absorption spectroscopy (XAS). The position of the edge energies and the intensities of the pre-edge (1s to 3d) peaks confirm that the Mn ion is in the +4 oxidation state. Fitting of the extended X-ray absorption fine structure (EXAFS) region reveals 4 N/O ligands at Mn–N avemore » = 1.89 Å and a fifth N/O ligand at 1.61 Å, corresponding to the terminal oxo ligand. This Mn–O bond length is elongated compared to the Mn V(O) starting material (Mn–O = 1.55 Å). The reactivity of Mn IV(O-LA)(TBP 8Cz •+) toward C–H substrates was examined, and it was found that H • abstraction from C–H bonds occurs in a 1:1 stoichiometry, giving a Mn IV complex and the dehydrogenated organic product. The rates of C–H cleavage are accelerated for the Mn IV(O-LA)(TBP 8Cz •+) valence tautomer as compared to the MnV(O) valence tautomer when LA = Zn II, B(C 6F 5) 3, and HBArF, whereas for LA = TFA, the C–H cleavage rate is slightly slower than when compared to MnV(O). A large, nonclassical kinetic isotope effect of k H/ k D = 25–27 was observed for LA = B(C 6F 5) 3 and HBAr F, indicating that H-atom transfer (HAT) is the rate-limiting step in the C–H cleavage reaction and implicating a potential tunneling mechanism for HAT. Furthermore, the reactivity of Mn IV(O-LA)(TBP 8Cz •+) toward C–H bonds depends on the strength of the Lewis acid. The HAT reactivity is compared with the analogous corrole complex Mn IV(O–H)(tpfc •+) recently reported.« less

High-valent manganese–oxo valence tautomers and the influence of Lewis/Brönsted acids on C–H bond cleavage

DOE PAGES

Baglia, Regina A.; Krest, Courtney M.; Yang, Tzuhsiung; ...

2016-09-30

The addition of Lewis or Brönsted acids (LA = Zn(OTf) 2, B(C 6F 5) 3, HBAr F, TFA) to the high-valent manganese–oxo complex Mn V(O)(TBP 8Cz) results in the stabilization of a valence tautomer Mn IV(O-LA)(TBP 8Cz •+). The Zn II and B(C 6F 5) 3 complexes were characterized by manganese K-edge X-ray absorption spectroscopy (XAS). The position of the edge energies and the intensities of the pre-edge (1s to 3d) peaks confirm that the Mn ion is in the +4 oxidation state. Fitting of the extended X-ray absorption fine structure (EXAFS) region reveals 4 N/O ligands at Mn–N avemore » = 1.89 Å and a fifth N/O ligand at 1.61 Å, corresponding to the terminal oxo ligand. This Mn–O bond length is elongated compared to the Mn V(O) starting material (Mn–O = 1.55 Å). The reactivity of Mn IV(O-LA)(TBP 8Cz •+) toward C–H substrates was examined, and it was found that H • abstraction from C–H bonds occurs in a 1:1 stoichiometry, giving a Mn IV complex and the dehydrogenated organic product. The rates of C–H cleavage are accelerated for the Mn IV(O-LA)(TBP 8Cz •+) valence tautomer as compared to the MnV(O) valence tautomer when LA = Zn II, B(C 6F 5) 3, and HBArF, whereas for LA = TFA, the C–H cleavage rate is slightly slower than when compared to MnV(O). A large, nonclassical kinetic isotope effect of k H/ k D = 25–27 was observed for LA = B(C 6F 5) 3 and HBAr F, indicating that H-atom transfer (HAT) is the rate-limiting step in the C–H cleavage reaction and implicating a potential tunneling mechanism for HAT. Furthermore, the reactivity of Mn IV(O-LA)(TBP 8Cz •+) toward C–H bonds depends on the strength of the Lewis acid. The HAT reactivity is compared with the analogous corrole complex Mn IV(O–H)(tpfc •+) recently reported.« less

Metal-organic framework assembled from erbium and a tetrapodal polyphosphonic acid organic linker.

PubMed

Mendes, Ricardo F; Firmino, Ana D G; Tomé, João P C; Almeida Paz, Filipe A

2018-06-01

A three-dimensional metal-organic framework (MOF), poly[[μ 6 -5'-pentahydrogen [1,1'-biphenyl]-3,3',5,5'-tetrayltetrakis(phosphonato)]erbium(III)] 2.5-hydrate], formulated as [Er(C 12 H 11 O 12 P 4 )]·2.5H 2 O or [Er(H 5 btp)]·2.5H 2 O (I) and isotypical with a Y 3+ -based MOF reported previously by our research group [Firmino et al. (2017b). Inorg. Chem. 56, 1193-1208], was constructed based solely on Er 3+ and on the polyphosphonic organic linker [1,1'-biphenyl]-3,3',5,5'-tetrakis(phosphonic acid) (H 8 btp). The present work describes our efforts to introduce lanthanide cations into the flexible network, demonstrating that, on the one hand, the compound can be obtained using three distinct experimental methods, i.e. hydro(solvo)thermal (Hy), microwave-assisted (MW) and one-pot (Op), and, on the other hand, that crystallite size can be approximately fine-tuned according to the method employed. MOF I contains hexacoordinated Er 3+ cations which are distributed in a zigzag inorganic chain running parallel to the [100] direction of the unit cell. The chains are, in turn, bridged by the anionic organic linker to form a three-dimensional 6,6-connected binodal network. This connectivity leads to the existence of one-dimensional channels (also running parallel to the [100] direction) filled with disordered and partially occupied water molecules of crystalization which are engaged in O-H...O hydrogen-bonding interactions with the [Er(H 5 btp)] framework. Additional weak π-π interactions [intercentroid distance = 3.957 (7) Å] exist between aromatic rings, which help to maintain the structural integrity of the network.

Hydroperoxide-dependent cooxidation of 13-cis-retinoic acid by prostaglandin H synthase.

PubMed

Samokyszyn, V M; Marnett, L J

1987-10-15

Reverse phase high pressure liquid chromatography was employed to separate the major products resulting from the hydroperoxide-dependent cooxidation of 13-cis-retinoic acid by microsomal and purified prostaglandin H (PGH) synthase. Several major oxygenated metabolites including 4-hydroxy-, 5,6-epoxy-, and 5,8-oxy-13-cis-retinoic acid were unambiguously identified on the basis of cochromatography with authentic standards, uv spectra, and mass spectral analysis. Identical product profiles were generated regardless of the type of oxidizing substrate employed, and heat-denatured microsomes or enzyme did not support oxidation. In addition, several geometric isomers including all trans-retinoic acid were identified. Isomerization to all trans-retinoic acid in microsomes occurred in the absence of exogenous hydroperoxide, was insensitive to inhibition by antioxidant, and was eliminated when heat-denatured preparations were substituted for intact microsomes. Conversely, isomerization to at least one other isomer required the addition of hydroperoxide and was sensitive to antioxidant inhibition. Addition of antioxidant to microsomal incubation mixtures inhibited the hydroperoxide-dependent generation of 5,6-epoxy- and 5,8-oxy-13-cis-retinoic acid and other oxygenated metabolites but stimulated the formation of 4-hydroxy-13-cis-retinoic acid. Under standard conditions, 77% of the original retinoid was metabolized resulting in products containing 1.25 oxygen atoms/oxygenated metabolite, and two dioxygen molecules were consumed per hydroperoxide reduced. Purified PGH synthase also supported O2 uptake during cooxidation of 13-cis-retinoic acid by H2O2 or 5-phenyl-4-pentenyl-1-hydroperoxide, and the initial velocities of O2 uptake were directly proportional to enzyme concentration. 13-cis-Retinoic acid effectively inhibited peroxidase-dependent cooxidation of guaiacol indicating a direct interaction of retinoid with peroxidase iron-oxo intermediates, and EPR spin trapping studies demonstrated the formation of retinoid-derived free radical intermediates. Incubating H2O2 with microsomal PGH synthase resulted in the initiation of lipid peroxidation, detected via measurement of malondialdehyde generation, that was inhibited by retinoid and suggests some limited involvement of lipid peroxidation in retinoid oxidation. Incubation of 13-cis-retinoic acid with hematin and 15-hydroperoxy-5,8,11,13-eicosatetraenoic acid in the presence of detergent, a system that generates high yields of peroxyl radicals, resulted in high yields of 5,6-epoxide; 4-hydroxy-13-cis-retinoic acid was not detected.(ABSTRACT TRUNCATED AT 400 WORDS)

Transcriptomic profiling provides molecular insights into hydrogen peroxide-induced adventitious rooting in mung bean seedlings.

PubMed

Li, Shi-Weng; Leng, Yan; Shi, Rui-Fang

2017-02-17

Hydrogen peroxide (H 2 O 2 ) has been known to function as a signalling molecule involved in the modulation of various physiological processes in plants. H 2 O 2 has been shown to act as a promoter during adventitious root formation in hypocotyl cuttings. In this study, RNA-Seq was performed to reveal the molecular mechanisms underlying H 2 O 2 -induced adventitious rooting. RNA-Seq data revealed that H 2 O 2 treatment greatly increased the numbers of clean reads and expressed genes and abundance of gene expression relative to the water treatment. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses indicated that a profound change in gene function occurred in the 6-h H 2 O 2 treatment and that H 2 O 2 mainly enhanced gene expression levels at the 6-h time point but reduced gene expression levels at the 24-h time point compared with the water treatment. In total, 4579 differentially expressed (2-fold change > 2) unigenes (DEGs), of which 78.3% were up-regulated and 21.7% were down-regulated; 3525 DEGs, of which 64.0% were up-regulated and 36.0% were down-regulated; and 7383 DEGs, of which 40.8% were up-regulated and 59.2% were down-regulated were selected in the 6-h, 24-h, and from 6- to 24-h treatments, respectively. The number of DEGs in the 6-h treatment was 29.9% higher than that in the 24-h treatment. The functions of the most highly regulated genes were associated with stress response, cell redox homeostasis and oxidative stress response, cell wall loosening and modification, metabolic processes, and transcription factors (TFs), as well as plant hormone signalling, including auxin, ethylene, cytokinin, gibberellin, and abscisic acid pathways. Notably, a large number of genes encoding for heat shock proteins (HSPs) and heat shock transcription factors (HSFs) were significantly up-regulated during H 2 O 2 treatments. Furthermore, real-time quantitative PCR (qRT-PCR) results showed that, during H 2 O 2 treatments, the expression levels of ARFs, IAAs, AUXs, NACs, RD22, AHKs, MYBs, PIN1, AUX15A, LBD29, LBD41, ADH1b, and QORL were significantly up-regulated at the 6- and/or 24-h time points. In contrast, PER1 and PER2 were significantly down-regulated by H 2 O 2 treatment. These qRT-PCR results strongly correlated with the RNA-Seq data. Using RNA-Seq and qRT-PCR techniques, we analysed the global changes in gene expression and functional profiling during H 2 O 2 -induced adventitious rooting in mung bean seedlings. These results strengthen the current understanding of H 2 O 2 -induced adventitious rooting and the molecular traits of H 2 O 2 priming in plants.

A Hydroxamic Acid Anchoring Group for Durable Dye-Sensitized Solar Cells Incorporating a Cobalt Redox Shuttle.

PubMed

Higashino, Tomohiro; Kurumisawa, Yuma; Cai, Ning; Fujimori, Yamato; Tsuji, Yukihiro; Nimura, Shimpei; Packwood, Daniel M; Park, Jaehong; Imahori, Hiroshi

2017-09-11

A hydroxamic acid group has been employed for the first time as an anchoring group for cobalt-based dye-sensitized solar cells (DSSCs). The porphyrin dye YD2-o-C8HA including a hydroxamic acid anchoring group exhibited a power conversion efficiency (η) of 6.4 %, which is close to that of YD2-o-C8, a representative porphyrin dye incorporating a conventional carboxylic acid. More importantly, YD2-o-C8HA was found to be superior to YD2-o-C8 in terms of both binding ability to TiO 2 and durability of cobalt-based DSSCs. Notably, YD2-o-C8HA photocells revealed a higher η-value (4.1 %) than YD2-o-C8 (2.8 %) after 500 h illumination. These results suggest that the hydroxamic acid can be used for DSSCs with other transition-metal-based redox shuttle to ensure high cell durability as well as excellent photovoltaic performance. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Catalytical Photocyclization of Arylamines with a-Olefins in the Synthesis of 2-Alkylquinoline

ERIC Educational Resources Information Center

Makhmutov, Aynur; Usmanov, Salavat; Mustafin, Ahat

2016-01-01

The article deals with the results of investigation of the process of catalytical photocyclization of aniline and aniline hydrochloride with a-olefins (hexene-1, heptene-1 and octene-1). The following compounds of d- and f-metals are tested as probable catalysts: CuSO4•5H2O, EuCl3•6H2O, PrCl3•6H2O, TbCl3•6H2O, La2O3, MnO2, NiSO4•6H2O, NiCl2•6H2O,…

An ab initio study of the molecular properties of the propyne water hydrogen-bonded complex

NASA Astrophysics Data System (ADS)

Lopes, Kelson C.; Araújo, Regiane C. M. U.; Rusu, Victor H.; Ramos, Mozart N.

2007-05-01

We have employed ab initio MP2 and DFT/B3LYP calculations with the 6-31++G(d,p) basis set to obtain structural, electronic and vibrational properties of the H-bonded complex between propyne and water. This study has revealed that H 2O can doubly complex with propyne forming a quasi five-membered ring. The first complexation occurs through the hydrogen bond between the acid hydrogen of H 2O and the C tbnd C triple bond, whereas the second complexation involves the oxygen atom of H 2O and the in-plane hydrogen atom of the methyl group in propyne. Our calculations have shown that the H-bond lengths between H⋯π and O⋯HC) are 2.419 and 2.707 Å, respectively, employing the DFT/B3LYP calculation whereas the corresponding MP2 values are 2.373 and 2.651 Å. The binding energies including both BSSE and ZPE corrections are -6.16 and -6.72 kJ mol -1, respectively, using the DFT/B3LYP and MP2 calculations. For example, the O-H stretching frequencies of water are decreased by -60 and -29 cm -1 using the DFT/B3LYP calculation, whereas the bending frequency is increased by +15 cm -1. As expected, the infrared intensities for the stretching modes are increased after complexation, especially involving the O-H b bond forming the hydrogen bond with the C tbnd C triple bond.

Chemistry of anti-AIDS and anticancer compounds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yan, S.

1992-01-01

Several types of prodrugs of 2[prime], 3[prime]-dideoxynucleosides were designed and synthesized for evaluation as anti-AIDS drugs. These prodrugs include 5[prime]-O-acyl-2[prime], 3[prime]-dideoxynucleosides, in which the acyl groups are derived from both aromatic and aliphatic acids, [alpha]-amino acids, diacylglycerol carbonic acids, and diacylglycerol carbamic acids. By applying the pyridium-dihydropyridine redox delivery system to deliver 2[prime], 3[prime]-dideoxynucleosides to the central nervous system, 1,4-dihydropyridine-2[prime], 3[prime]-dideoxy-inosine and -adenosine compounds were synthesized. 5[prime]-Esters of 2[prime], 3[prime]-dideoxyinosine and 2[prime], 3[prime]-dideoxyadenosine were evaluated for their activity against the HIV-1 virus and for delivery to the central nervous system (CNS). The isomerization, hydrolysis, and oxidation of alkyl 1,4-dihydro-N-methylpyridine-3-carboxylates weremore » studied by [sup 1]H and [sup 13]C NMR spectroscopy. Three intermediates, 1,4-dihydro-N-methylpyridine-3-carboxylic acid, alkyl (methyl or isopropyl) 1,6-dihydro-N-methylpyridine-3-carboxylate, and 1,6-dihydro-N-methylpyridine-3-carboxylic acid, were observed by [sup 1]H and [sup 13]C NMR spectroscopy, and their percentages in solution were determined. The structures of the 1,6-dihydropyridine intermediates were confirmed by comparison of the NMR spectra with those of an authentic model compound, methyl N-(4-chlorobenzyl)-1,6-dihydropyridine-3-carboxylate. The rate of hydrolysis of alkyl 1,4-dihydro-N-methylpyridine-3-carboxylates depends on the steric bulk of the O-alkyl group. A new type of 1,4-dihydropyridine drug delivery system with a three-carbon spacer group, 9-[2,3-di-O-acetyl-5-O-[3-(1,4-dihydro-N-methylpyridine-3-carboxamido)propionyl]-[beta]-D-arabinofuranosyl]adenine was designed, synthesized, and evaluated to deliver ara-ADA to the CNS for treatment of herpes encephalitis.« less

Thermal wet decomposition of Prussian Blue: implications for prebiotic chemistry.

PubMed

Ruiz-Bermejo, Marta; Rogero, Celia; Menor-Salván, César; Osuna-Esteban, Susana; Martín-Gago, José Angel; Veintemillas-Verdaguer, Sabino

2009-09-01

The complex salt named Prussian Blue, Fe4[Fe(CN)6]3 x 15 H2O, can release cyanide at pH > 10. From the point of view of the origin of life, this fact is of interest, since the oligomers of HCN, formed in the presence of ammonium or amines, leads to a variety of biomolecules. In this work, for the first time, the thermal wet decomposition of Prussian Blue was studied. To establish the influence of temperature and reaction time on the ability of Prussian Blue to release cyanide and to subsequently generate other compounds, suspensions of Prussian Blue were heated at temperatures from room temperature to 150 degrees at pH 12 in NH3 environment for several days. The NH3 wet decomposition of Prussian Blue generated hematite, alpha-Fe2O3, the soluble complex salt (NH4)4[Fe(CN6)] x 1.5 H2O, and several organic compounds, the nature and yield of which depend on the experimental conditions. Urea, lactic acid, 5,5-dimethylhydantoin, and several amino acids and carboxylic acids were identified by their trimethylsilyl (TMS) derivatives. HCN, cyanogen (C2N2), and formamide (HCONH2) were detected in the gas phase by GC/MS analysis.

Highly selective and sensitive detection of metal ions and nitroaromatic compounds by an anionic europium(iii) coordination polymer.

PubMed

Feyisa Bogale, Raji; Ye, Junwei; Sun, Yuan; Sun, Tongxin; Zhang, Siqi; Rauf, Abdul; Hang, Cheng; Tian, Peng; Ning, Guiling

2016-07-05

A luminescent Eu(iii)-based coordination polymer, {[Eu(H2O)5(BTEC)][H(C5H6N2)]·3H2O} () has been synthesized under hydrothermal conditions using 1,2,4,5-benzenetetracarboxylic acid (H4BTEC) as a linker. Compound possesses an anionic zig-zag chain constructed from the BTEC ligands and [EuO4(H2O)5] nodes. The protonated 4-aminopyridine groups as guests are located between chains. exhibits the characteristic sharp emission bands of Eu(3+) at 578, 593, 615, 652 and 693 nm upon excitation at 290 nm. The strong emission of could be quenched effectively by trace amounts of Fe(3+) ions even in the presence of other metal ions including Al(3+), Ca(2+), Cd(2+), Co(2+), Cr(3+), Cu(2+), Fe(2+), K(+), Mg(2+), Mn(2+), Pd(2+) and Zn(2+). Similarly, also exhibits superior selectivity and sensitivity towards 4-nitrophenol (4-NP) compared with other competing interfering analytes, such as 2,4,6-trinitrophenol, 2,6-dinitrotolune, 4-nitrotoluene, nitrobenzene, 1,3-dinitrobenzene, o-xylene, nitromethane, nitropropane, phenol, 4-bromophenol and bromobenzene, through a fluorescence quenching mechanism. The possible fluorescence quenching mechanisms are discussed. Moreover, could be used as a visual fluorescent test paper for selectively detecting trace amounts of Fe(3+) and 4-NP.

Coordination Polymers of 5-Alkoxy Isophthalic Acids

DOE Office of Scientific and Technical Information (OSTI.GOV)

McCormick, Laura J.; Morris, Samuel A.; Slawin, Alexandra M. Z.

The topology of coordination polymers containing 5-alkoxy isophthalic acids and first row transition metals was found to be dependent on the combination of solvent system used and length of the alkyl chain. Four different framework types were thus identified: Phase A, M 6(ROip) 5(OH) 2(H 2O) 4·xH 2O (M = Co and R = Et, Pr, or nBu, or M = Zn and R = Et); Phase B,M 2(ROip) 2(H 2O) (M = Co or Zn and R = Et, Pr, nBu, or iBu, or M = Mn and R = nBu or iBu); Phase C, Zn 3(EtOip) 2(OH) 2;more » and Phase D, Zn 2(EtOip) 2(H 2O) 3. Preliminary screening of the NO storage and release capabilities of the Co-containing materials is also reported.« less

Coordination Polymers of 5-Alkoxy Isophthalic Acids

DOE PAGES

McCormick, Laura J.; Morris, Samuel A.; Slawin, Alexandra M. Z.; ...

2016-08-23

The topology of coordination polymers containing 5-alkoxy isophthalic acids and first row transition metals was found to be dependent on the combination of solvent system used and length of the alkyl chain. Four different framework types were thus identified: Phase A, M 6(ROip) 5(OH) 2(H 2O) 4·xH 2O (M = Co and R = Et, Pr, or nBu, or M = Zn and R = Et); Phase B,M 2(ROip) 2(H 2O) (M = Co or Zn and R = Et, Pr, nBu, or iBu, or M = Mn and R = nBu or iBu); Phase C, Zn 3(EtOip) 2(OH) 2;more » and Phase D, Zn 2(EtOip) 2(H 2O) 3. Preliminary screening of the NO storage and release capabilities of the Co-containing materials is also reported.« less

Study of Perfluorophosphonic Acid Surface Modifications on Zinc Oxide Nanoparticles.

PubMed

Quiñones, Rosalynn; Shoup, Deben; Behnke, Grayce; Peck, Cynthia; Agarwal, Sushant; Gupta, Rakesh K; Fagan, Jonathan W; Mueller, Karl T; Iuliucci, Robbie J; Wang, Qiang

2017-11-28

In this study, perfluorinated phosphonic acid modifications were utilized to modify zinc oxide (ZnO) nanoparticles because they create a more stable surface due to the electronegativity of the perfluoro head group. Specifically, 12-pentafluorophenoxydodecylphosphonic acid, 2,3,4,5,6-pentafluorobenzylphosphonic acid, and (1H,1H,2H,2H-perfluorododecyl)phosphonic acid have been used to form thin films on the nanoparticle surfaces. The modified nanoparticles were then characterized using infrared spectroscopy, X-ray photoelectron spectroscopy, and solid-state nuclear magnetic resonance spectroscopy. Dynamic light scattering and scanning electron microscopy-energy dispersive X-ray spectroscopy were utilized to determine the particle size of the nanoparticles before and after modification, and to analyze the film coverage on the ZnO surfaces, respectively. Zeta potential measurements were obtained to determine the stability of the ZnO nanoparticles. It was shown that the surface charge increased as the alkyl chain length increases. This study shows that modifying the ZnO nanoparticles with perfluorinated groups increases the stability of the phosphonic acids adsorbed on the surfaces. Thermogravimetric analysis was used to distinguish between chemically and physically bound films on the modified nanoparticles. The higher weight loss for 12-pentafluorophenoxydodecylphosphonic acid and (1H,1H,2H,2H-perfluorododecyl)phosphonic acid modifications corresponds to a higher surface concentration of the modifications, and, ideally, higher surface coverage. While previous studies have shown how phosphonic acids interact with the surfaces of ZnO, the aim of this study was to understand how the perfluorinated groups can tune the surface properties of the nanoparticles.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Niu, Yan-Fei; Cui, Li-Ting; Han, Jie, E-mail: chan@ouhk.edu.hk

The role of auxiliary solvents in the formation of MOFs has been investigated for a series of Mn{sup II}-based framework systems. Reactions of 4,4′,4″-nitrilotribenzoic acid (H{sub 3}L) with Mn{sup II} through varying auxiliary solvents of the medium resulted in the formation of diversified multinuclear Mn{sup II} subunits in four new coordination polymers: [Mn{sub 3}(L)(HCOO){sub 3}(DEF){sub 3}] (1), [Mn{sub 3}(L){sub 2}(EtOH){sub 2}]·DMF (2), [Mn{sub 5}(L){sub 4}(H{sub 2}O){sub 2}]·2(H{sub 2}NMe{sub 2}){sup +}·4DMF·2H{sub 2}O (3), and [Mn{sub 3}(L){sub 2}(py){sub 4}(H{sub 2}O)]·H{sub 2}O (4) (H{sub 3}L=4,4′,4′-nitrilotribenzoic acid, DMF=dimethylformamide, DEF=N,N-diethylformamide, py=pyridine). These four compounds were fully characterized by single-crystal X-ray diffraction, showing interesting SBUs variations.more » For compound 1, it displays a (3,6)-connected kgd net with wheel [Mn{sub 6}] cluster serving as SBU, whereas in 2, the sequence of Mn{sub 3}(COO){sub 9}(EtOH){sub 2} is repeated by inversion centers located between Mn1 and Mn3 to form an infinite Mn-carboxylate chain, which are further interlinked by L{sup 3−} ligands to form a 3D architecture. In 3, the pentanuclear Mn{sub 5}(CO{sub 2}){sub 12} clusters are interlinked to form a layer, which are further pillared by L{sup 3−} to generate a 3D network. Compound 4 has a (3,6)-connected network in which the SBU is a linear trimeric Mn{sub 3}(COO){sub 6}(py){sub 4}(H{sub 2}O) cluster. In addition, the thermal stabilities, X-ray powder diffraction of all the compounds were studied, photoluminescence behaviors of compounds 1, 3 and 4 are discussed. - Graphical abstract: Supramolecular assembly of C{sub 3}-symmetric ligand 4,4′,4″-nitrilotribenzoic acid (H{sub 3}L) with Mn{sup II} through varying auxiliary solvents of the medium resulted in the formation of diversified multinuclear Mn{sup II} subunits in four new coordination polymers. The results exhibit the structures of Mn-SBUs in these MOFs largely depend on the ancillary solvents involved in the reactions. Display Omitted.« less

Ferromagnetic coupling in the three-dimensional malonato-bridged gadoliniumIII complex [Gd2(mal)3(H2O)6] (H2mal = malonic acid).

PubMed

Hernández-Molina, María; Ruiz-Pérez, Catalina; López, Trinidad; Lloret, Francesc; Julve, Miguel

2003-09-08

The novel gadolinium(III) complex of formula [Gd(2)(mal)(3)(H(2)O)(6)] (1) (H(2)mal = 1,3-propanedioic acid) has been prepared and characterized by X-ray diffraction analysis. Crystal data for 1: monoclinic, space group I2/a, a = 11.1064(10) A, b = 12.2524(10) A, c =13.6098(2) A, beta = 92.925(10) degrees, U = 1849.5(3) A(3), Z = 4. Compound 1 is a three-dimensional network made up of malonate-bridged gadolinium(III) ions where the malonate exhibits two bridging modes, eta(5)-bidentate + unidentate and eta(3):eta(3) + bis(unidentate). The gadolinium atom is nine-coordinate with three water molecules and six malonate oxygen atoms from three malonate ligands forming a distorted monocapped square antiprism. The shortest metal-metal separations are 4.2763(3) A [through the oxo-carboxylate bridge] and 6.541(3) A [through the carboxylate in the anti-syn coordination mode]. The value of the angle at the oxo-carboxylate atom is 116.8(2) degrees. Variable-temperature magnetic susceptibility measurements reveal the occurrence of a significant ferromagnetic interaction through the oxo-carboxylate pathway (J = +0.048(1) cm(-1), H = -JS(Gd(1)) x S(Gd(1a))).

Thermodynamic properties and crystal structure refinement of ferricopiapite, coquimbite, rhomboclase, and Fe2(SO4)3(H2O)5

USGS Publications Warehouse

Majzlan, J.; Navrotsky, A.; McCleskey, R. Blaine; Alpers, Charles N.

2006-01-01

Enthalpies of formation of ferricopiapite [nominally Fe4.67(SO4)6(OH)2 (H2O)20]. coquimbite [Fe2(SO4)3(H2O)9], rhomboclase [(H3O)Fe(SO4)2 (H2O)3], and Fe2(SO4)3(H2O)5 were measured by acid (5 N HCl) solution calorimetry. The samples were characterized by wet chemical analyses and synchrotron powder X-ray diffraction (XRD). The refinement of XRD patterns gave lattice parameters, atomic positions, thermal factors, and occupancies of the sites. The calculated formulae differ slightly from the nominal compositions: Fe4.78(SO4)6 (OH)2.34(H2O)20.71 (ferricopiapite), (Fe1.47Al0.53)(SO4)3 (H2O)9.65 (coquimbite), (H3O)1.34Fe(SO4)2.17 (H2O)3.06 (rhomboclase), and Fe2(SO4)3 (H2O)5.03. All thermodynamic data are given per mole of these formulae. The measured standard enthalpies (in kJ/mol) of formation from the elements (crystalline Fe, Al, S, and ideal gases O2 and H2) at T = 298.15 K are -4115.8??4.1 [Fe2(SO4)3 (H2O)5.03], -12045.1??9.2 (ferricopiapite), -5738.4??3.3 (coquimbite), and -3201.1??2.6 (rhomboclase). Standard entropy (S??) was estimated as a sum of entropies of oxide, hydroxide, and sulfate components. The estimated S?? (in J/mol.K) values for the iron sulfates are 488.2 [Fe2(SO4)3 (H2O)5.03], 1449.2 (ferricopiapite), 638.3 (coquimbite), and 380.1 (rhomboclase). The calculated Gibbs free energies of formation (in kJ/mol) are -3499.7??4.2 [Fe2(SO4)3 (H2O)5.03], -10089.8??9.3 (ferricopiapite), -4845.6??3.3 (coquimbite), and -2688.0??2.7 (rhomboclase). These results combined with other available thermodynamic data allow construction of mineral stability diagrams in the FeIII2(SO4)3-FeII SO4-H2O system. One such diagram is provided, indicating that the order of stability of ferric sulfate minerals with decreasing pH in the range of 1.5 to -0.5 is: hydronium jarosite, ferricopiapite, and rhomboclase. ?? 2006 E. Schweizerbart'sche Verlagsbuchhandlung.

A performance comparison of choline biosensors: anodic or cathodic detections of H2O2 generated by enzyme immobilized on a conducting polymer.

PubMed

Rahman, Md Aminur; Park, Deog-Soo; Shim, Yoon-Bo

2004-07-15

Amperometric choline biosensors were fabricated by the covalent immobilization of an enzyme of choline oxidase (ChO) and a bi-enzyme of ChO/horseradish peroxidase (ChO/HRP) onto poly-5,2':5',2"-terthiophene-3'-carboxylic acid (poly-TTCA) modified electrodes (CPMEs). A sensor modified with ChO utilized the oxidation process of enzymatically generated H(2)O(2) in a choline solution at +0.6V. The other one modified with ChO/HRP utilized the reduction process of H(2)O(2) in a choline solution at -0.2V. Experimental parameters affecting the sensitivity of sensors, such as pH, applied potential, and temperature were optimized. A performance comparison of two sensors showed that one based on ChO/HRP/CPME had a linear range from 1.0 x 10(-6) to 8.0 x 10(-5) M and the other based on ChO/CPME from 1.0 x 10(-6) to 5.0 x 10(-5) M. The detection limits for choline employing ChO/HRP/CPME and ChO/CPME were determined to be about 1.0 x 10(-7) and 4.0 x 10(-7) M, respectively. The response time of sensors was less than 5s. Sensors showed good selectivity to interfering species. The long-term storage stability of the sensor based on ChO/HRP/CPME was longer than that based on ChO/CPME.

Effects of Low Phytanic Acid-Concentrated DHA on Activated Microglial Cells: Comparison with a Standard Phytanic Acid-Concentrated DHA.

PubMed

Ruiz-Roso, María Belén; Olivares-Álvaro, Elena; Quintela, José Carlos; Ballesteros, Sandra; Espinosa-Parrilla, Juan F; Ruiz-Roso, Baltasar; Lahera, Vicente; de Las Heras, Natalia; Martín-Fernández, Beatriz

2018-05-30

Docosahexaenoic acid (DHA, 22:6 n-3) is an essential omega-3 (ω-3) long chain polyunsaturated fatty acid of neuronal membranes involved in normal growth, development, and function. DHA has been proposed to reduce deleterious effects in neurodegenerative processes. Even though, some inconsistencies in findings from clinical and pre-clinical studies with DHA could be attributed to the presence of phytanic acid (PhA) in standard DHA treatments. Thus, the aim of our study was to analyze and compare the effects of a low PhA-concentrated DHA with a standard PhA-concentrated DHA under different neurotoxic conditions in BV-2 activated microglial cells. To this end, mouse microglial BV-2 cells were stimulated with either lipopolysaccharide (LPS) or hydrogen peroxide (H 2 O 2 ) and co-incubated with DHA 50 ppm of PhA (DHA (PhA:50)) or DHA 500 ppm of PhA (DHA (PhA:500)). Cell viability, superoxide anion (O 2 - ) production, Interleukin 6 (L-6), cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), glutathione peroxidase (GtPx), glutathione reductase (GtRd), Caspase-3, and the brain-derived neurotrophic factor (BDNF) protein expression were explored. Low PhA-concentrated DHA protected against LPS or H 2 O 2 -induced cell viability reduction in BV-2 activated cells and O 2 - production reduction compared to DHA (PhA:500). Low PhA-concentrated DHA also decreased COX-2, IL-6, iNOS, GtPx, GtRd, and SOD-1 protein expression when compared to DHA (PhA:500). Furthermore, low PhA-concentrated DHA increased BDNF protein expression in comparison to DHA (PhA:500). The study provides data supporting the beneficial effect of low PhA-concentrated DHA in neurotoxic injury when compared to a standard PhA-concentrated DHA in activated microglia.

[Studies on chemical constituents from rhizome of Anemone flaccida].

PubMed

Zhang, Lan-tian; Takaishi, Yoshihisa; Zhang, Yan-wen; Duan, Hong-quan

2008-07-01

To study the chemical constituents from Anemone flaccida. Chemical constituents were isolated by repeated column chromatography (silica gel, Toyopearl HW-40C and preparative HPLC). The structures were elucidated on the basis of spectral data analysis. Twelve triterpenes were isolated and their structures were identified as follow: oleanolic acid (1), oleanolic acid 3-O-beta-D-glccopyranosyl-(1-->2)-beta-D-xylopyranoside (2), eleutheroside K (3), oleanolic acid 3-O-alpha-L-rhamnopyranosyl-(1-->2)-beta-D-xylopyranoside (4), oleanolic acid 3-O-beta-D-glccopyranosyl-(1-->2)-alpha-L-arabinofurnoside (5), oleanolic acid 3-O-beta-D-glccuronopyranose (6), oleanolic acid 3-O-beta-D-glccuronopyranose methyl ester (7), oleanolic acid 28-O-alpha-L-rhamnopyranosyl(1-->4)-beta-D-glccopyranosyl (1-->6)-beta-D-glccopyranosyl (8), oleanolic acid 3-O-beta-D-glccuronopyranose 28-O-alpha-L-rhamnopyranosyl (1-->4)-beta-D-glccopyranosyl (1-->6)-beta-D-glccopyranoside (9), oleanolic acid 3-O-beta-D-glccopyranosyl methyl ester 28-O-alpha-L-rhamnopyranosyl (1-->4)-beta-D-glccopyranosyl (1-->6)-beta-D-glccopyranoside (10), oleanolic acid 3-O-beta-D-glccopyranosyl-(1-->2)-beta-D-xylopyranosyl-28-O-alpha-L-rhamnopyranosyl (1-->4)-beta-D-glccopyranosyl (1-->6)-beta-D-glccopyranoside (11), oleanolic acid 3-O-alpha-L-rh-amnopyranosyl-(1-->2)-alpha-L-arabinopyrnosyl-28-O-alpha-L-rhamnopyranosyl (1-->4)-beta-D-glccopyranosyl (1-->6)-beta-D-glccopyranoside (12). compounds 5-8, 10, 12 were isolated from this plant for the first time. Compounds 2, 5 and 11 showed positive anti-tumor activities.

Degradation of histamine in the presence of ascorbic acid and Cu2+ ion; involvement of hydrogen peroxide.

PubMed

Yamamoto, I; Ohmori, H

1981-01-01

In the presence, but not in the absence of Cu2+, ascorbate decomposes histamine in citrate phosphate buffer (pH 6.5) at 37 degrees, but not at 0 degrees. The breakdown is completely inhibited by catalase, but only slightly by superoxide dismutase, and scavengers of OH. like benzoic acid, ethanol or potassium iodide. A1 O2 scavenger, alpha-tocopherol also did not show significant effects on the reaction. On the other hand, addition of H2O2 to the reaction mixture markedly enhances the rate of histamine breakdown induced by ascorbate or ascorbate-Cu2+ systems. However, H2O2 alone cannot breakdown histamine even in the presence of Cu2+. Histamine breakdown induced by ascorbate appears to be dependent upon the autooxidation of this vitamin. From these results and the findings reported by Chatterjee et al. that the products of its aerobic oxidation, dehydroascorbic acid and H2O2 were ineffective in reacting with histamine in the presence of Cu2+, it is concluded that the combination of H2O2 and the intermediate of ascorbate oxidation (monodehydroascorbic acid or other unstable species), both of which are produced during the autooxidation of ascorbate, plays a major role in the histamine transformation by ascorbate-Cu2+ system.

Weakly-bridged dimeric diorganotin(IV) compounds derived from pyruvic acid hydrazone Schiff base ligands: Synthesis, characterization and crystal structures

NASA Astrophysics Data System (ADS)

Hong, Min; Yin, Han-Dong; Cui, Ji-Chun

2011-03-01

We report the synthesis of four diorganotin(IV) compounds of Schiff base pyruvic acid hydrazone derivatives formulated as [R 2SnLY] 2, where L 1 is 2-SC 4H 3CON 2C(CH 3)CO 2 with Y = CH 3CH 2CH 2CH 2OH, R = n-Bu ( 1); L 2 is C 6H 5CON 2C(CH 3)CO 2 with Y = CH 3CH 2OH, R = p-F-Bz ( 2); L 3 is 2-HOC 6H 4CON 2C(CH 3)CO 2 with Y dbnd H 2O, R = p-CN -Bz ( 3); and L 4 is 4-NO 2-C 6H 4CON 2C(CH 3)CO 2 with Y dbnd CH 3CH 2OH, R = Bz ( 4). The structures of all compounds have been established by a combination of single-crystal X-ray diffraction analysis, 1H and 119Sn NMR spectroscopy, IR spectroscopy, and elemental analysis. Studies reveal that four ligands present the same coordination mode with tin center, which all present tridentate ONO donor Schiff bases and coordinate to the tin center in an enolic form. In compounds 1- 4, each tin atom is seven-coordinated and exhibits a distorted pentagonal bipyramid with a planar SnO 4N unit and two apical alkyl carbon atoms, thus forming a weakly-bridged dimeric molecule. Additionally, the distance of Sn⋯O bridge in each compound is obviously affected by the choice of different alkyl groups and coordination solvent molecules, which fluctuates in the range of 2.571(5)-2.839(4) Å. Furthermore, the supramolecular structure analysis show that there are two types of supramolecular infrastructures, 1D chain or 2D network, which are formed by intermolecular O-H···N or C-H⋯X (X = O, N or F) hydrogen bonds.

Production of bioadditives from glycerol esterification over zirconia supported heteropolyacids.

PubMed

Zhu, Shanhui; Zhu, Yulei; Gao, Xiaoqing; Mo, Tao; Zhu, Yifeng; Li, Yongwang

2013-02-01

The synthesis of bioadditives for biofuels from glycerol esterification with acetic acid was performed over zirconia supported heteropolyacids catalysts using H(4)SiW(12)O(40) (HSiW), H(3)PW(12)O(40) (HPW) and H(3)PMo(12)O(40) (HPMo) as active compounds. The as-prepared catalysts were characterized by N(2)-physisorption, XRD, Raman spectroscopy, NH(3)-TPD, FTIR of pyridine adsorption and H(2)O-TPD. Among the catalysts tested, HSiW/ZrO(2) achieved the best catalytic performance owing to the better combination of surface Brønsted acid sites and hydrothermal stability. A 93.6% combined selectivity of glyceryl diacetate and glyceryl triacetate with complete glycerol conversion was obtained at 120°C and 4h of reaction time in the presence of HSiW/ZrO(2). This catalyst also presented consistent activity for four consecutive reaction cycles, while HPW/ZrO(2) and HPMo/ZrO(2) exhibited distinct deactivation after reusability tests. In addition, HSiW/ZrO(2) can be resistant to the impurities present in bulk glycerol. Copyright © 2012 Elsevier Ltd. All rights reserved.

Crystal Analysis of Multi Phase Calcium Phosphate Nanoparticles Containing Different amount of Magnesium

NASA Astrophysics Data System (ADS)

Gozalian, Afsaneh; Behnamghader, Ali Asghar; Moshkforoush, Arash

In this study, Mg doped hydroxyapatite [(Ca, Mg)10(PO4)6(OH)2] and β-tricalcium phosphate nanoparticles were synthesized via sol gel method. Triethyl phosphite, calcium nitrate tetrahydrate and magnesium nitrate hexahydrate were used as P, Ca and Mg precursors. The ratio of (Ca+Mg)/P and the amount of magnesium (x) were kept constant at 1.67 and ranging x = 0 up to 3 in molecular formula of Ca10-xMgx (PO4)6(OH)2, respectively. Phase composition and chemical structure were performed using X-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FT-IR). Phase percentages, crystallite size, degree of crystallinity and lattice parameters were investigated. The presence of magnesium led to form the Mg doped tricalcium phosphate (β-TCMP) and Mg doped hydroxyapatite (Mg-HA). Based on the results of this study, lattice parameters, degree of crystallinity and crystallite size decreased with magnesium content. In addition, with increasing magnesium content, the amount of CaO phase decreased whereas the amount of MgO phase increased significantly. Obtained results can be used for new biomaterials design.

TiO2 nanoparticles versus TiO2-SiO2 nanocomposites: A comparative study of photo catalysis on acid red 88

NASA Astrophysics Data System (ADS)

Balachandran, K.; Venckatesh, Rajendran; Sivaraj, Rajeshwari; Rajiv, P.

2014-07-01

A novel, simple, less time-consuming and cost-effective wet chemical technique was used to synthesis TiO2 nanoparticles and TiO2-SiO2 nanocomposites using Titanium tetra isopropoxide (TTIP) as a precursor relatively at low temperature in acidic pH. Titania sol was prepared by hydrolysis of TTIP and was mixed with silicic acid and tetrahydrofuran mixture. The reaction was carried out under vigorous stirring for 6 h and dried at room temperature. The resulting powders were characterized by UV-Visible spectroscopy, Fourier transform infrared (FT-IR), X-ray diffraction, scanning electron microscope (SEM) and transmission electron microscope (TEM). The grain size of the particles was calculated by X-ray diffraction, surface morphology and chemical composition was determined from scanning electron microscopy-energy dispersive spectroscopy, metal oxide stretching was confirmed from FT-IR spectroscopy, band gap was calculated using UV-Visible spectroscopy. Surface area of the composite as calculated by BET analyzer and it was found to be 65 and 75 m2/g for TiO2 and TiO2-SiO2 respectively. The photocatalytic experiments were performed with aqueous solution of acid red 88 with TiO2 and TiO2-SiO2 batch studies for 4 h irradiation, direct photolysis of TiO2 and TiO2-SiO2 contributed 94.2% and 96.5% decomposition in solar radiation for the optimized concentration of acid red 88.

Fabrication of a Functionalized Magnetic Bacterial Nanocellulose with Iron Oxide Nanoparticles

PubMed Central

Arias, Sandra L.; Shetty, Akshath R.; Senpan, Angana; Echeverry-Rendón, Mónica; Reece, Lisa M.; Allain, Jean Paul

2016-01-01

In this study, bacterial nanocellulose (BNC) produced by the bacteria Gluconacetobacter xylinus is synthesized and impregnated in situ with iron oxide nanoparticles (IONP) (Fe3O4) to yield a magnetic bacterial nanocellulose (MBNC). The synthesis of MBNC is a precise and specifically designed multi-step process. Briefly, bacterial nanocellulose (BNC) pellicles are formed from preserved G. xylinus strain according to our experimental requirements of size and morphology. A solution of iron(III) chloride hexahydrate (FeCl3·6H2O) and iron(II) chloride tetrahydrate (FeCl2·4H2O) with a 2:1 molar ratio is prepared and diluted in deoxygenated high purity water. A BNC pellicle is then introduced in the vessel with the reactants. This mixture is stirred and heated at 80 °C in a silicon oil bath and ammonium hydroxide (14%) is then added by dropping to precipitate the ferrous ions into the BNC mesh. This last step allows forming in situ magnetite nanoparticles (Fe3O4) inside the bacterial nanocellulose mesh to confer magnetic properties to BNC pellicle. A toxicological assay was used to evaluate the biocompatibility of the BNC-IONP pellicle. Polyethylene glycol (PEG) was used to cover the IONPs in order to improve their biocompatibility. Scanning electron microscopy (SEM) images showed that the IONP were located preferentially in the fibril interlacing spaces of the BNC matrix, but some of them were also found along the BNC ribbons. Magnetic force microscope measurements performed on the MBNC detected the presence magnetic domains with high and weak intensity magnetic field, confirming the magnetic nature of the MBNC pellicle. Young's modulus values obtained in this work are also in a reasonable agreement with those reported for several blood vessels in previous studies. PMID:27285589

Fabrication of a Functionalized Magnetic Bacterial Nanocellulose with Iron Oxide Nanoparticles.

PubMed

Arias, Sandra L; Shetty, Akshath R; Senpan, Angana; Echeverry-Rendón, Mónica; Reece, Lisa M; Allain, Jean Paul

2016-05-26

In this study, bacterial nanocellulose (BNC) produced by the bacteria Gluconacetobacter xylinus is synthesized and impregnated in situ with iron oxide nanoparticles (IONP) (Fe3O4) to yield a magnetic bacterial nanocellulose (MBNC). The synthesis of MBNC is a precise and specifically designed multi-step process. Briefly, bacterial nanocellulose (BNC) pellicles are formed from preserved G. xylinus strain according to our experimental requirements of size and morphology. A solution of iron(III) chloride hexahydrate (FeCl3·6H2O) and iron(II) chloride tetrahydrate (FeCl2·4H2O) with a 2:1 molar ratio is prepared and diluted in deoxygenated high purity water. A BNC pellicle is then introduced in the vessel with the reactants. This mixture is stirred and heated at 80 °C in a silicon oil bath and ammonium hydroxide (14%) is then added by dropping to precipitate the ferrous ions into the BNC mesh. This last step allows forming in situ magnetite nanoparticles (Fe3O4) inside the bacterial nanocellulose mesh to confer magnetic properties to BNC pellicle. A toxicological assay was used to evaluate the biocompatibility of the BNC-IONP pellicle. Polyethylene glycol (PEG) was used to cover the IONPs in order to improve their biocompatibility. Scanning electron microscopy (SEM) images showed that the IONP were located preferentially in the fibril interlacing spaces of the BNC matrix, but some of them were also found along the BNC ribbons. Magnetic force microscope measurements performed on the MBNC detected the presence magnetic domains with high and weak intensity magnetic field, confirming the magnetic nature of the MBNC pellicle. Young's modulus values obtained in this work are also in a reasonable agreement with those reported for several blood vessels in previous studies.

Polynuclear Hydroxido-Bridged Complexes of Platinum(IV) with Terminal Nitrato Ligands.

PubMed

Vasilchenko, Danila; Berdugin, Semen; Tkachev, Sergey; Baidina, Iraida; Romanenko, Galina; Gerasko, Olga; Korenev, Sergey

2015-05-18

For the first time the polynuclear hydroxido-bridged platinum(IV) nitrato complexes with nuclearity higher than two were isolated from nitric acid solutions of [Pt(H2O)2(OH)4] and crystallized as supramolecular compounds of macrocyclic cavitands cucurbit[n]uril (CB[n], n = 6,8) and 18-crown-6 ether: [Pt4(μ3-OH)2(μ2-OH)4(NO3)10]·CB[6]·25H2O (I), [Pt6(μ3-OH)4(μ2-OH)6(NO3)12](NO3)2·CB[8]·50H2O (II), and [H3O⊂18-crown-6]2[Pt2(μ2-OH)2(NO3)8][Pt4(μ3-OH)2(μ2-OH)4(NO3)10] (III). The isolation of the compounds in the single crystalline state allows the determination of the structure of the tetranuclear and hexanuclear complexes [Pt4(μ3-OH)2(μ2-OH)4(NO3)10] and [Pt6(μ3-OH)4(μ2-OH)6(NO3)12](2+), which have been previously unknown in the solid state. Stability of Ptx(OH)y cores of the polynuclear nitrato complexes toward alkaline hydrolysis was verified by (195)Pt NMR spectroscopy. Analysis of (195)Pt NMR spectra of the compound III reveals that addition of every Pt(μ-OH)2Pt ring results in ∼260 ppm downfield shift relative to the mononuclear form, which allows the prediction of signal positions for complexes of higher nuclearity.

Reversible Sialylation: Synthesis of CMP-NeuAc from 5′-CMP using α2,3-sialyl O-glycan, glycolipid and macromolecule based donors allow for the synthesis of diverse sialylated products

PubMed Central

Chandrasekaran, E.V.; Xue, Jun; Xia, Jie; Locke, Robert D.; Matta, Khushi L.; Neelamegham, Sriram

2008-01-01

Sialyltransferases transfer sialic acid from CMP-NeuAc to an acceptor molecule. Trans-sialidases of parasites transfer α2,3 linked sialic acid from one molecule to another without the involvement of CMP-NeuAc. Here, we report another type of sialylation termed reverse sialylation catalyzed by mammalian sialyltransferase ST3Gal-II. This enzyme synthesizes CMP-NeuAc by transferring NeuAc from the NeuAcα2,3Galβ1,3GalNAcα-unit of O-glycans, 3-sialyl globo unit of glycolipids and sialylated macromolecules to 5′-CMP. CMP-NeuAc produced in situ is utilized by the same enzyme to sialylate other O-glycans and by other sialyltransferases such as ST6Gal-I and ST6GalNAc-I forming α2,6 sialylated compounds. ST3Gal-II also catalyzed the conversion of 5′-UMP to UMP-NeuAc, which was found to be an inactive sialyl donor. Reverse sialylation proceeded without the need for free sialic acid, divalent metal ions or energy. The direct sialylation using CMP-NeuAc as well as the formation of CMP-NeuAc from 5′-CMP had a wide optimum range (pH 5.2–7.2 and 4.8–6.4 respectively) whereas the entire reaction comprising in situ production of CMP-NeuAc and sialylation of acceptor had a sharp optimum at pH 5.6 (the activity level 50% at pH 5.2 & 6.8 and 25% at pH 4.8 & 7.2). Several properties distinguish forward/conventional vs. reverse sialylation: i. Sodium citrate inhibited forward sialylation but not reverse sialylation. ii. 5′-CDP, a potent forward sialyltransferase inhibitor, did not inhibit the conversion of 5′-CMP to CMP-NeuAc. iii. The mucin core 2 compound 3-O-sulfoα2,3Galβ1,4GlcNAcβ1,6(Galβ1,3)GalNAcα-O-Bn, an efficient acceptor for ST3Gal-II, inhibited the conversion of 5′-CMP to CMP-NeuAc. A significant level of reverse sialylation activity is noted in human prostate cancer cell lines LNCaP and PC3. Overall, the study demonstrates that the sialyltransferase reaction is readily reversible in the case of ST3Gal-II and can be exploited for the enzymatic synthesis of diverse sialyl products. PMID:18067323

Metal-organometallic polymers and frameworks derived from facially metalated arylcarboxylates

NASA Astrophysics Data System (ADS)

Kumalah Robinson, Sayon A.

The interest in coordination polymers, also known as metal-organic frameworks, has risen drastically over the past 2 decades. In this time, the field has matured and given rise to a diverse range of crystalline structures possessing various functionalities. Coordination polymers are typically formed from the self assembly of metal ions which serve as nodes and organic ligands which act as bridges. By the careful selection of the organic ligand and the metal ion, the overall physical properties of the material may be tuned. In this work, the use of organometallic bridging ligands are explored using facially metalated aryl carboxylates ligands to synthesize metal-organometallic frameworks (MOMFs). Therefore, with the aim of synthesizing [CpM]+-functionalized (M = FeII, RuII; Cp = cyclopentadienyl) coordination polymers and metal organic frameworks, various [CpFe]+and [CpRu] + functionalized aryl carboxylates were synthesized and characterized. In particular, the [CpFe]+-functionalized benzoic, terephthalic and trimesic acids as well as the [CpRu]+-functionalized terephthalic acid were made. Using the [CpFe]+ complexes of the benzoic and terephthalic acid as bridging ligands, a number of 1D and 2D coordination polymers were synthesized. For instance, the reaction of [CpFe]+-functionalized benzoic acid with CdCl2 yielded the 1D chain of [Cd(benzoate)Cl 2]˙H2O whilst the reaction of [CpFe]+-functionalized terephthalic acid with Cu(NO3)2˙6H2O yielded a 2D square grid sheet. Using the [CpFe]+-functionalized terephthalic acid, a series of polymorphic, 3D metal-organometallic frameworks of the general formula [M3(terephthalate)4(mu-H2O)2(H 2O)2][NO3]2˙xsolvent (M = Co II, NiII ; solvent = EtOH, DMF, H2O) were synthesized and fully characterized. The polymorphic nature of these frameworks may be attributed to the different orientations that the [CpFe]+ moiety may adapt within the cavities in the 3D frameworks. The selectivity of the desolvated forms of the polymorphs for various alcohols was also probed. A framework having the same 3D topology but slightly different composition as the polymorphic frameworks of [M3(terephthalate)4(mu-H 2O)2(H2O)2][NO3]2˙ xsolvent was obtained using MnBr2˙4H2O. The solvothermal reaction of [CpFe]+-functionalized terephthalic acid and Co(NO3)2˙6H2O afforded the first microporous metal-organometallic phosphate. This 3D framework formed a cubic, 12-connected face centered net featuring a novel dodecanuclear truncated tetrahedral node consisting of [CpFe(terephthalate)]+, CoII, F- and phosphate ions. Lastly, the [CpFe]+-functionalized terephthalic acid was successfully reticulated into the MIL-88 and MIL 53 framework topologies indicating that the metalated ligand may be used to synthesis both known and novel 3D metal organic frameworks.

Regulation of 2-5A Dependent RNase at the Level of its Phosphorylation

DTIC Science & Technology

1991-06-26

extract as follows: 25 ul wheat germ extract 10 ul H2O 1 ul RNasin ribonuclease inhibitor (40 u/ml) 7 ul ImM amino acid mixture 1 ul IM...diacylglycerol (DAG) 2. TPA 3. Indolactam Figure 6. Chemical structure of: 1. H-7 (A kinase inhibitor) 2. okadaic acid (A phosphatase inhibitor) Figure 7...elevating agents: Forskolin and Cholera toxin Figure 17. Down-regulation of 2-5A-depRNase by Okadaic 77 acid : A phosphatase inhibitor Figure 18

UV and solar photo-degradation of naproxen: TiO₂ catalyst effect, reaction kinetics, products identification and toxicity assessment.

PubMed

Jallouli, Nabil; Elghniji, Kais; Hentati, Olfa; Ribeiro, Ana R; Silva, Adrián M T; Ksibi, Mohamed

2016-03-05

Direct photolysis and TiO2-photocatalytic degradation of naproxen (NPX) in aqueous solution were studied using a UV lamp and solar irradiation. The degradation of NPX was found to be in accordance with pseudo-first order kinetics, the photocatalytic process being more efficient than photolysis. The NPX removal by photolysis (pHinitial 6.5) was 83% after 3h, with 11% of chemical oxygen demand (COD) reduction, whereas the TiO2-UV process led to higher removals of both NPX (98%) and COD (25%). The apparent pseudo-first-order rate constant (kapp) for NPX degradation by photolysis ranged from 0.0050 min(-1) at pH 3.5 to 0.0095 min(-1) at pH 6.5, while it was estimated to be 0.0063 min(-1) under acidic conditions in photocatalysis, increasing by 4-fold at pH 6.5. Ultra High Performance Liquid chromatography (UHPLC) coupled with a triple quadrupole detector and also a hybrid mass spectrometer which combines the linear ion trap triple quadrupole (LTQ) and OrbiTrap mass analyser, were used to identify NPX degradation products. The main intermediates detected were 1-(6-methoxynaphtalene-2-yl) ethylhydroperoxide, 2-ethyl-6-methoxynaphthalene, 1-(6-methoxynaphtalen-2-yl) ethanol, 1-(6-methoxynaphtalen-2-yl) ethanone and malic acid. Solar photocatalysis of NPX showed COD removals of 33% and 65% after 3 and 4h of treatment, respectively, and some reduction of acute toxicity, evaluated by the exposure of Eisenia andrei to OECD soils spiked with NPX-treated solutions. Copyright © 2015 Elsevier B.V. All rights reserved.

Isolation of homoleptic platinum oxyanionic complexes with doubly protonated diazacrown cation

NASA Astrophysics Data System (ADS)

Vasilchenko, Danila; Tkachev, Sergey; Baidina, Iraida; Romanenko, Galina; Korenev, Sergey

2017-02-01

Doubly protonated diazacrown ether cation (1,4,10,13-tetraoxa-7,16-diazoniacyclooctadecane DCH22+) was used for the efficient isolation of the homoleptic platinum complexes [Pt(NO3)6]2- and [Pt(C2O4)2]2- to crystalline solid phases from solutions containing mixtures of related platinum complexes. DCH22+ molecules in nitric acid solution were shown to prevent the condensation of mononuclear [Pt(H2O)n(NO3)6-n]n-2 species.

STRUCTURAL ANALYSIS OF THE COMBUSTION SYNTHESIZED Y3+ DOPED CERIA (Ce0.9Y0.1O1.95)

NASA Astrophysics Data System (ADS)

Jeyanthi, C. Esther; Siddheswaran, R.; Kumar, Pushpendra; Mangalaraja, R. V.; Siva Shankar, V.; Rajarajan, K.

2013-07-01

Y3+ doped CeO2 nanopowders (Ce0.9Y0.1O1.95, abbreviated as YDC) were synthesized by citrate-nitrate-auto combustion process using cerium nitrate hexahydrate, yttrium nitrate hexahydrate and citric acid. The as-synthesized powders were calcined at 700°C and converted into dense bodies followed by sintering at 1200°C. The microstructure of the synthesized powders and sintered bodies were examined by scanning electron microscopy (SEM). The surface morphology of the nanoparticles and clusters were also analysed by transmission electron microscopy (TEM). The particles size of the YDC was found to be in the range from 10 to 30 nm, which is in good agreement with the crystallite size calculated from X-ray peak broadening method. Also, the X-ray diffraction confirmed that the Ce0.9Y0.1O1.95 crystallizes as the cubic fluorite structure of pure ceria. The optical absorption by functional molecules, impurities and oxygen vacancies were analysed by FTIR and Raman spectroscopic studies. From the FTIR spectrum, the absorption peak found at 530 cm-1 is attributed to the vibrations of metal-oxygen bonds. The characteristic Raman peak was found to be 468 cm-1, and the minute absorption of oxygen vacancies were observed in the region 500-640 cm-1.

The effect of ligand substituent on crystal packing: Structural and theoretical studies of two Ga(III) supramolecular compounds

NASA Astrophysics Data System (ADS)

Soleimannejad, Janet; Nazarnia, Esfandiar

2016-07-01

A new Ga(III) supramolecular compound (4,4‧-bipyH2)[Ga(hpydc)2]2·7H2O (2) (where H2hpydc = 4-hydroxy-pyridine-2,6-dicarboxylic acid and 4,4‧-bipy = 4,4‧-bipyridine) was synthesized using the proton transfer reaction. Compound 2 was structurally characterized using single crystal X-ray diffraction, and it was shown that its asymmetric unit consists of two independent anionic Ga(III) complexes, one fully protonated 4,4‧-bipyridine and seven uncoordinated water molecules. In order to understand the effect of pyridine OH substituent on supramolecular interactions and crystal packing, compound 2 was compared with (bipyH2)[Ga(pydc)2]·(H2pydc)·4H2O (1) (where H2pydc = pyridine-2,6-dicarboxylic acid), that does not have an OH group on the pyridine ligand. The Density Functional Theory (DFT) and Natural Bond Orbital (NBO) calculations and also Atoms in Molecules (AIM) analysis were used to analyze the non-covalent interactions in both complexes. The calculation of non-covalent interactions' energy provides a useful means to investigate their effects in the crystal packing.

Mass spectrometric monitoring of oxidation of aliphatic C6-C8 hydrocarbons and ethanol in low pressure oxygen and air plasmas.

PubMed

Usmanov, Dilshadbek T; Chen, Lee Chuin; Hiraoka, Kenzo; Wada, Hiroshi; Nonami, Hiroshi; Yamabe, Shinichi

2016-12-01

Experimental and theoretical studies on the oxidation of saturated hydrocarbons (n-hexane, cyclohexane, n-heptane, n-octane and isooctane) and ethanol in 28 Torr O 2 or air plasma generated by a hollow cathode discharge ion source were made. Ions corresponding to [M + 15] + and [M + 13] + in addition to [M - H] + and [M - 3H] + were detected as major ions where M is the sample molecule. The ions [M + 15] + and [M + 13] + were assigned as oxidation products, [M - H + O] + and [M - 3H + O] + , respectively. By the tandem mass spectrometry analysis of [M - H + O] + and [M - 3H + O] + , H 2 O, olefins (and/or cycloalkanes) and oxygen-containing compounds were eliminated from these ions. Ozone as one of the terminal products in the O 2 plasma was postulated as the oxidizing reagent. As an example, the reactions of C 6 H 14 +• with O 2 and of C 6 H 13 + (CH 3 CH 2 CH + CH 2 CH 2 CH 3 ) with ozone were examined by density functional theory calculations. Nucleophilic interaction of ozone with C 6 H 13 + leads to the formation of protonated ketone, CH 3 CH 2 C(=OH + )CH 2 CH 2 CH 3 . In air plasma, [M - H + O] + became predominant over carbocations, [M - H] + and [M - 3H] + . For ethanol, the protonated acetic acid CH 3 C(OH) 2 + (m/z 61.03) was formed as the oxidation product. The peaks at m/z 75.04 and 75.08 are assigned as protonated ethyl formate and protonated diethyl ether, respectively, and that at m/z 89.06 as protonated ethyl acetate. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Hydration Energies and Structures of Alkaline Earth Metal Ions, M2+ (H2O)n, n = 5–7, M = Mg, Ca, Sr, and Ba

PubMed Central

Rodriguez-Cruz, Sandra E.; Jockusch, Rebecca A.

2005-01-01

The evaporation of water from hydrated alkaline earth metal ions, produced by electrospray ionization, was studied in a Fourier transform mass spectrometer. Zero-pressure-limit dissociation rate constants for loss of a single water molecule from the hydrated divalent metal ions, M2+(H2O)n (M = Mg, Ca, and Sr for n = 5–7, and M = Ba for n = 4–7), are measured as a function of temperature using blackbody infrared radiative dissociation. From these values, zero-pressure-limit Arrhenius parameters are obtained. By modeling the dissociation kinetics using a master equation formalism, threshold dissociation energies (Eo) are determined. These reactions should have a negligible reverse activation barrier; therefore, Eo values should be approximately equal to the binding energy or hydration enthalpy at 0 K. For the hepta- and hexahydrated ions at low temperature, binding energies follow the trend expected on the basis of ionic radii: Mg > Ca > Sr > Ba. For the hexahydrated ions at high temperature, binding energies follow the order Ca > Mg > Sr > Ba. The same order is observed for the pentahydrated ions. Collisional dissociation experiments on the tetrahydrated species result in relative dissociation rates that directly correlate with the size of the metals. These results indicate the presence of two isomers for hexahydrated magnesium ions: a low-temperature isomer in which the six water molecules are located in the first solvation shell, and a high-temperature isomer with the most likely structure corresponding to four water molecules in the inner shell and two water molecules in the second shell. These results also indicate that the pentahydrated magnesium ions have a structure with four water molecules in the first solvation shell and one in the outer shell. The dissociation kinetics for the hexa- and pentahydrated clusters of Ca2+, Sr2+, and Ba2+ are consistent with structures in which all the water molecules are located in the first solvation shell. PMID:16429612

Initial Reaction(s) in Biotransformation of CL-20 Is Catalyzed by Salicylate 1-Monooxygenase from Pseudomonas sp. Strain ATCC 29352

PubMed Central

Bhushan, Bharat; Halasz, Annamaria; Spain, Jim C.; Hawari, Jalal

2004-01-01

CL-20 (2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane) (C6H6N12O12), a future-generation high-energy explosive, is biodegradable by Pseudomonas sp. strain FA1 and Agrobacterium sp. strain JS71; however, the nature of the enzyme(s) involved in the process was not understood. In the present study, salicylate 1-monooxygenase, a flavin adenine dinucleotide (FAD)-containing purified enzyme from Pseudomonas sp. strain ATCC 29352, biotransformed CL-20 at rates of 0.256 ± 0.011 and 0.043 ± 0.003 nmol min−1 mg of protein−1 under anaerobic and aerobic conditions, respectively. The disappearance of CL-20 was accompanied by the release of nitrite ions. Using liquid chromatography/mass spectrometry in the negative electrospray ionization mode, we detected a metabolite with a deprotonated mass ion [M − H]− at 345 Da, corresponding to an empirical formula of C6H6N10O8, produced as a result of two sequential N denitration steps on the CL- 20 molecule. We also detected two isomeric metabolites with [M − H]− at 381 Da corresponding to an empirical formula of C6H10N10O10. The latter was a hydrated product of the metabolite C6H6N10O8 with addition of two H2O molecules, as confirmed by tests using 18O-labeled water. The product stoichiometry showed that each reacted CL-20 molecule produced about 1.7 nitrite ions, 3.2 molecules of nitrous oxide, 1.5 molecules of formic acid, and 0.6 ammonium ion. Diphenyliodonium-mediated inhibition of salicylate 1-monooxygenase and a comparative study between native, deflavo, and reconstituted enzyme(s) showed that FAD site of the enzyme was involved in the biotransformation of CL-20 catalyzed by salicylate 1-monooxygenase. The data suggested that salicylate 1-monooxygenase catalyzed two oxygen-sensitive single-electron transfer steps necessary to release two nitrite ions from CL-20 and that this was followed by the secondary decomposition of this energetic chemical. PMID:15240281

Initial reaction(s) in biotransformation of CL-20 is catalyzed by salicylate 1-monooxygenase from Pseudomonas sp. strain ATCC 29352.

PubMed

Bhushan, Bharat; Halasz, Annamaria; Spain, Jim C; Hawari, Jalal

2004-07-01

CL-20 (2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane) (C(6)H(6)N(12)O(12)), a future-generation high-energy explosive, is biodegradable by Pseudomonas sp. strain FA1 and Agrobacterium sp. strain JS71; however, the nature of the enzyme(s) involved in the process was not understood. In the present study, salicylate 1-monooxygenase, a flavin adenine dinucleotide (FAD)-containing purified enzyme from Pseudomonas sp. strain ATCC 29352, biotransformed CL-20 at rates of 0.256 +/- 0.011 and 0.043 +/- 0.003 nmol min(-1) mg of protein(-1) under anaerobic and aerobic conditions, respectively. The disappearance of CL-20 was accompanied by the release of nitrite ions. Using liquid chromatography/mass spectrometry in the negative electrospray ionization mode, we detected a metabolite with a deprotonated mass ion [M - H](-) at 345 Da, corresponding to an empirical formula of C(6)H(6)N(10)O(8), produced as a result of two sequential N denitration steps on the CL- 20 molecule. We also detected two isomeric metabolites with [M - H](-) at 381 Da corresponding to an empirical formula of C(6)H(10)N(10)O(10). The latter was a hydrated product of the metabolite C(6)H(6)N(10)O(8) with addition of two H(2)O molecules, as confirmed by tests using (18)O-labeled water. The product stoichiometry showed that each reacted CL-20 molecule produced about 1.7 nitrite ions, 3.2 molecules of nitrous oxide, 1.5 molecules of formic acid, and 0.6 ammonium ion. Diphenyliodonium-mediated inhibition of salicylate 1-monooxygenase and a comparative study between native, deflavo, and reconstituted enzyme(s) showed that FAD site of the enzyme was involved in the biotransformation of CL-20 catalyzed by salicylate 1-monooxygenase. The data suggested that salicylate 1-monooxygenase catalyzed two oxygen-sensitive single-electron transfer steps necessary to release two nitrite ions from CL-20 and that this was followed by the secondary decomposition of this energetic chemical.

Amino acid repletion does not decrease muscle protein catabolism during hemodialysis.

PubMed

Raj, Dominic S C; Adeniyi, Oladipo; Dominic, Elizabeth A; Boivin, Michel A; McClelland, Sandra; Tzamaloukas, Antonios H; Morgan, Nancy; Gonzales, Lawrence; Wolfe, Robert; Ferrando, Arny

2007-06-01

Intradialytic protein catabolism is attributed to loss of amino acids in the dialysate. We investigated the effect of amino acid infusion during hemodialysis (HD) on muscle protein turnover and amino acid transport kinetics by using stable isotopes of phenylalanine, leucine, and lysine in eight patients with end-stage renal disease (ESRD). Subjects were studied at baseline (pre-HD), 2 h of HD without amino acid infusion (HD-O), and 2 h of HD with amino acid infusion (HD+AA). Amino acid depletion during HD-O augmented the outward transport of amino acids from muscle into the vein. Increased delivery of amino acids to the leg during HD+AA facilitated the transport of amino acids from the artery into the intracellular compartment. Increase in muscle protein breakdown was more than the increase in synthesis during HD-O (46.7 vs. 22.3%, P < 0.001). Net balance (nmol.min(-1).100 ml (-1)) was more negative during HD-O compared with pre-HD (-33.7 +/- 1.5 vs. -6.0 +/- 2.3, P < 0.001). Despite an abundant supply of amino acids, the net balance (-16.9 +/- 1.8) did not switch from net release to net uptake. HD+AA induced a proportional increase in muscle protein synthesis and catabolism. Branched chain amino acid catabolism increased significantly from baseline during HD-O and did not decrease during HD+AA. Protein synthesis efficiency, the fraction of amino acid in the intracellular pool that is utilized for muscle protein synthesis decreased from 42.1% pre-HD to 33.7 and 32.6% during HD-O and HD+AA, respectively (P < 0.01). Thus amino acid repletion during HD increased muscle protein synthesis but did not decrease muscle protein breakdown.

Structural elucidation, EPR and magnetic property of a Co(III) complex salt incorporating 4,4‧-bipyridine and 5-sulfoisophthalate

NASA Astrophysics Data System (ADS)

Das, Kuheli; Datta, Amitabha; Pevec, Andrej; Mane, Sandeep B.; Rameez, Mohammad; Garribba, Eugenio; Akitsu, Takashiro; Tanka, Shinnosuke

2018-01-01

The cobalt(III) derivative [Co3(sip)4(bipy)2(H2O)10][Co(bipy)2(H2O)4]3(sip)2·20H2O (1) has been hydro(solvo) thermally synthesized by combining sodium 5-sulfoisophthalate (sipH2Na) as organic linker, divalent cobalt nitrate hexahydrate as metal salt and the flexible N-donor ancillary ligand bipy (4,4‧-bipyridine). Compound 1 is an ionic solid consisting of both cobalt containing cations and anions and also in addition 5-sulfoisophthalate anions. Cobalt containing cations in the crystal structure are mononuclear complex while cobalt containing anion is a discrete trinuclear species. The π-π interaction present in 1 results in chain supramolecular structure. The encapsulation of the cobalt compound displays a moderate luminescent property. On temperature dependent magnetic study, it is revealed that the corresponding effective magnetic moment is 5.27 B.M. at 300 K, which suggests isolated Co(III) species with S = 2 (theoretical value is 4.90 B M.) and thus 1 shows a rare paramagnetic behavior.

1D helix, 2D brick-wall and herringbone, and 3D interpenetration d10 metal-organic framework structures assembled from pyridine-2,6-dicarboxylic acid N-oxide.

PubMed

Wen, Li-Li; Dang, Dong-Bin; Duan, Chun-Ying; Li, Yi-Zhi; Tian, Zheng-Fang; Meng, Qing-Jin

2005-10-03

Five novel interesting d(10) metal coordination polymers, [Zn(PDCO)(H2O)2]n (PDCO = pyridine-2,6-dicarboxylic acid N-oxide) (1), [Zn2(PDCO)2(4,4'-bpy)2(H2O)2.3H2O]n (bpy = bipyridine) (2), [Zn(PDCO)(bix)]n (bix = 1,4-bis(imidazol-1-ylmethyl)benzene) (3), [Zn(PDCO)(bbi).0.5H2O]n (bbi = 1,1'-(1,4-butanediyl)bis(imidazole)) (4), and [Cd(PDCO)(bix)(1.5).1.5H2O]n (5), have been synthesized under hydrothermal conditions and structurally characterized. Polymer 1 possesses a one-dimensional (1D) helical chainlike structure with 4(1) helices running along the c-axis with a pitch of 10.090 Angstroms. Polymer 2 has an infinite chiral two-dimensional (2D) brick-wall-like layer structure in the ac plane built from achiral components, while both 3 and 4 exhibit an infinite 2D herringbone architecture, respectively extended in the ac and ab plane. Polymer 5 features a most remarkable and unique three-dimensional (3D) porous framework with 2-fold interpenetration related by symmetry, which contains channels in the b and c directions, both distributed in a rectangular grid fashion. Compounds 1-5, with systematic variation in dimensionality from 1D to 2D to 3D, are the first examples of d(10) metal coordination polymers into which pyridinedicarboxylic acid N-oxide has been introduced. In addition, polymers 1, 4, and 5 display strong blue fluorescent emissions in the solid state. Polymer 3 exhibits a strong SHG response, estimated to be approximately 0.9 times that of urea.

Acidophilic denitrifiers dominate the N2O production in a 100-year-old tea orchard soil.

PubMed

Huang, Ying; Long, Xi-En; Chapman, Stephen J; Yao, Huaiying

2015-03-01

Aerobic denitrification is the main process for high N2O production in acid tea field soil. However, the biological mechanisms for the high emission are not fully understood. In this study, we examined N2O emission and denitrifier communities in 100-year-old tea soils with four pH levels (3.71, 5.11, 6.19, and 7.41) and four nitrate concentration (0, 50, 200, and 1000 mg kg(-1) of NO3 (-)-N) addition. Results showed the highest N2O emission (10.1 mg kg(-1) over 21 days) from the soil at pH 3.71 with 1000 mg kg(-1) NO3 (-) addition. The N2O reduction and denitrification enzyme activity in the acid soils (pH <7.0) were significantly higher than that of soils at pH 7.41. Moreover, TRF 78 of nirS and TRF 187 of nosZ dominated in soils of pH 3.71, suggesting an important role of acidophilic denitrifiers in N2O production and reduction. CCA analysis also showed a negative correlation between the dominant denitrifier ecotypes (nirS TRF 78, nosZ TRF 187) and soil pH. The representative sequences were identical to those of cultivated denitrifiers from acidic soils via phylogenetic tree analysis. Our results showed that the acidophilic denitrifier adaptation to the acid environment results in high N2O emission in this highly acidic tea soil.

Gallium(III)-Containing, Sandwich-Type Heteropolytungstates: Synthesis, Solution Characterization, and Hydrolytic Studies toward Phosphoester and Phosphoanhydride Bond Cleavage.

PubMed

Kandasamy, Balamurugan; Vanhaecht, Stef; Nkala, Fiona Marylyn; Beelen, Tessa; Bassil, Bassem S; Parac-Vogt, Tatjana N; Kortz, Ulrich

2016-09-19

The gallium(III)-containing heteropolytungstates [Ga4(H2O)10(β-XW9O33)2](6-) (X = As(III), 1; Sb(III), 2) were synthesized in aqueous acidic medium by reaction of Ga(3+) ions with the trilacunary, lone-pair-containing [XW9O33](9-). Polyanions 1 and 2 are isostructural and crystallized as the hydrated sodium salts Na6[Ga4(H2O)10(β-AsW9O33)2]·28H2O (Na-1) and Na6[Ga4(H2O)10(β-SbW9O33)2]·30H2O (Na-2) in the monoclinic space group P21/c, with unit cell parameters a = 16.0218(12) Å, b = 15.2044(10) Å, c = 20.0821(12) Å, and β = 95.82(0)°, as well as a = 16.0912(5) Å, b = 15.2178(5) Å, c = 20.1047(5) Å, and β = 96.2(0)°, respectively. The corresponding tellurium(IV) derivative [Ga4(H2O)10(β-TeW9O33)2](4-) (3) was also prepared, by direct reaction of sodium tungstate, tellurium(IV) oxide, and gallium nitrate. Polyanion 3 crystallized as the mixed rubidium/sodium salt Rb2Na2[Ga4(H2O)10(β-TeW9O33)2]·28H2O (RbNa-3) in the triclinic space group P1̅ with unit cell parameters a = 12.5629(15) Å, b = 13.2208(18) Å, c = 15.474(2) Å, α = 80.52(1)°, β = 84.37(1)°, and γ = 65.83(1)°. All polyanions 1-3 were characterized in the solid state by single-crystal XRD, FT-IR, TGA, and elemental analysis, and polyanion 2 was also characterized in solution by (183)W NMR and UV-vis spectroscopy. Polyanion 2 was used as a homogeneous catalyst toward adenosine triphosphate (ATP) and the DNA model substrate 4-nitrophenylphosphate, monitored by (1)H and (31)P NMR spectroscopy. The encapsulated gallium(III) centers in 2 promote the Lewis acidic synergistic activation of the hydrolysis of ATP and DNA model substrates at a higher rate in near-physiological conditions. A strong interaction of 2 with the P-O bond of ATP was evidenced by changes in chemical shift values and line broadening of the (31)P nucleus in ATP upon addition of the polyanion.

Hydrolysis of Ketene Catalyzed by Formic Acid: Modification of Reaction Mechanism, Energetics, and Kinetics with Organic Acid Catalysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Louie, Matthew K.; Francisco, Joseph S.; Verdicchio, Marco

2015-05-14

The hydrolysis of ketene (H2C=C=O) to form acetic acid involving two water molecules and also separately in the presence of one to two water molecules and formic acid (FA) was investigated. Our results show that, while the currently accepted indirect mechanism, involving addition of water across the carbonyl C=O bond of ketene to form an ene-diol followed by tautomerization of the ene-diol to form acetic acid, is the preferred pathway when water alone is present, with formic acid as catalyst, addition of water across the ketene C=C double bond to directly produce acetic acid becomes the kinetically favored pathway formore » temperatures below 400 K. We find not only that the overall barrier for ketene hydrolysis involving one water molecule and formic acid (H2C2O + H2O + FA) is significantly lower than that involving two water molecules (H2C2O + 2H(2)O) but also that FA is able to reduce the barrier height for the direct path, involving addition of water across the C=C double bond, so that it is essentially identical with (6.4 kcal/mol) that for the indirect ene-diol formation path involving addition of water across the C=O bond. For the case of ketene hydrolysis involving two water molecules and formic acid (H2C2O + 2H(2)O + FA), the barrier for the direct addition of water across the C=C double bond is reduced even further and is 2.5 kcal/mol lower relative to the ene-diol path involving addition of water across the C=O bond. In fact, the hydrolysis barrier for the H2C2O + 2H(2)O + FA reaction through the direct path is sufficiently low (2.5 kcal/mol) for it to be an energetically accessible pathway for acetic acid formation under atmospheric conditions. Given the structural similarity between acetic and formic acid, our results also have potential implications for aqueous-phase chemistry. Thus, in an aqueous environment, even in the absence of formic acid, though the initial mechanism for ketene hydrolysis is expected to involve addition of water across the carbonyl bond as is currently accepted, the production and accumulation of acetic acid will likely alter the preferred pathway to one involving addition of water across the ketene C=C double bond as the reaction proceeds.« less

Synthesis of hydroxyapatite whiskers through dissolution reprecipitation process using EDTA

NASA Astrophysics Data System (ADS)

Seo, Dong Seok; Lee, Jong Kook

2008-04-01

Hydroxyapatite (HA) has been of interest in many industrial applications, such as ion exchange, catalysis and biomaterials. Chelating agents have often been used to prepare inorganic powders in the form of sphere, rod, whisker and fiber. In this study, HA whiskers were synthesized directly from typically shaped HA powders by refluxing at 80 and 100 °C for 24 h using ethylenediamine tetraacetic acid (EDTA). 3% or 6% of hydrogen peroxide (H 2O 2) was used to promote precipitation of HA crystals. The pH of the solution was adjusted at 7 or 9 by adding ammonia solution. The higher the H 2O 2 concentration, pH value and refluxing temperature, the longer and thinner whiskers were formed. The whiskers produced at 100 °C with 6% of H 2O 2 and pH 9 had the highest aspect ratio of about 50-60 (a length of 3 μm and a width of 0.05 μm).

Synthesis, structural characterization and DFT calculation on a square-planar Ni(II) complex of a compartmental Schiff base ligand

NASA Astrophysics Data System (ADS)

Biswas, Surajit; Dolai, Malay; Dutta, Arpan; Ali, Mahammad

2016-12-01

Reaction of a symmetric compartmental Schiff-base ligand, (H2L) with nickel(II) perchlorate hexahydrate in 1:1 M ratio in methanol gives rise to a mononuclear nickel(II) compound, NiL (1). The compound has been characterized by C, H, N microanalyses and UV-Vis spectra. The single crystal X-ray diffraction studies reveal a square planar geometry around the Ni(II) center. The compound crystallizes in monoclinic system with space group C2/c with a = 21.6425(6), b = 9.9481(3), c = 13.1958(4) Å, β = 107.728(2)°, V = 2706.16(14) Å3 and Z = 4. Ground state DFT optimization and TDDFT calculations on the ligand and complex were performed to get their UV-Vis spectral pattern.

Aquatic plant-derived changes in oil sands naphthenic acid signatures determined by low-, high- and ultrahigh-resolution mass spectrometry.

PubMed

Headley, John V; Peru, Kerry M; Armstrong, Sarah A; Han, Xiumei; Martin, Jonathan W; Mapolelo, Mmilili M; Smith, Donald F; Rogers, Ryan P; Marshall, Alan G

2009-02-01

Mass spectrometry is a common tool for studying the fate of complex organic compound mixtures in oil sands processed water (OSPW), but a comparison of low-, high- ( approximately 10 000), and ultrahigh-resolution ( approximately 400 000) instrumentation for this purpose has not previously been made. High-resolution quadrupole time-of-flight mass spectrometry (QTOF MS) and ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), with negative-ion electrospray ionization, provided evidence for the selective dissipation of components in OSPW. Dissipation of oil sands naphthenic acids (NAs with general formula C(n)H(2n+z)O(2) where n is the number of carbon atoms, and Z is zero or a negative even number describing the number of rings) was masked (by components such as fatty acids, O(3), O(5), O(6), O(7), SO(2), SO(3), SO(4), SO(5), SO(6), and NO(4) species) at low resolution (1000) when using a triple quadrupole mass spectrometer. Changes observed in the relative composition of components in OSPW appear to be due primarily to the presence of plants, specifically cattails (Typha latifolia) and their associated microorganisms. The observed dissipation included a range of heteratomic species containing O(2), O(3), O(4), and O(5), present in Athabasca oil sands acid extracts. For the heteratomic O(2) species, namely naphthenic acids, an interesting structural relationship suggests that low and high carbon number NAs are dissipated by the plants preferentially, with a minimum around C(14)/C(15). Other heteratomic species containing O(6), O(7), SO(2), SO(3), SO(4), SO(5), SO(6), and NO(4) appear to be relatively recalcitrant to the cattails and were not dissipated to the same extent in planted systems. Copyright 2009 John Wiley & Sons, Ltd.

Preparation of LaB{sub 3}O{sub 6}:Eu{sup 3+} phosphors by a facile precursor method and their luminescent properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Xia; Liang, Pan; Huang, Hong-Sheng

2014-04-01

Graphical abstract: LaB{sub 3}O{sub 6}:Eu{sup 3+} phosphor was obtained by calcining the precursor which was synthesized by boric acid melting method. It (a) exhibits much stronger PL intensity than that (b) prepared by conventional solid state reaction method. - Highlights: • A calcining precursor method was used for preparation of LaB{sub 3}O{sub 6}:Eu{sup 3+} phosphor. • Precursor was prepared by boric acid melting method. • The luminescence intensity of LaB{sub 3}O{sub 6}:Eu{sup 3+} was enhanced by the present method. - Abstract: The LaB{sub 3}O{sub 6}:Eu{sup 3+} phosphors were prepared by calcining the precursors which were synthesized by boric acid meltingmore » method using rare earth oxide and boric acid as raw materials, and they were characterized by EDS, XRD, IR, SEM and PL. The influences of reaction temperature for the preparation of precursor and subsequent calcination temperature and time of precursor on the luminescence properties of LaB{sub 3}O{sub 6}:Eu{sup 3+} phosphor were investigated. The results showed that the LaB{sub 3}O{sub 6}:Eu{sup 3+} phosphors with maximum luminescent intensity were obtained by calcining precursor at 1000 °C for 6 h, in which the precursor was prepared at 200 °C for 72 h. Compared with the conventional high temperature solid-state reaction method, the pure LaB{sub 3}O{sub 6}:Eu{sup 3+} phosphor can be obtained at relatively lower calcination temperature by the precursor method and exhibits much stronger emission intensity.« less

A new ferulic acid ester from Rhodiola wallichiana var. cholaensis (Crassulaceae).

PubMed

Song, Yaling; Zhou, Jianming; Wang, Xuejing; Xie, Xue; Zhao, Yiwu; Ni, Fuyong; Huang, Wenzhe; Wang, Zhenzhong; Xiao, Wei

2018-01-01

A new ferulic acid ester, 6-feruloyloxyhexanoic acid (1), was isolated along with 10 known ones (2-11), from the concentrated water extract of Rhodiola wallichiana var. cholaensis. Their chemical structures were elucidated on the basis of extensive spectroscopic methods including Two-dimensional nuclear magnetic resonance (2D NMR) experiments. Compound 3 was isolated from this plant for the first time. The protective effects against H 2 O 2 -induced myocardial cell injury in cultured H9c2 cells were also evaluated. Compounds 1, 5 and 7-11 provided significant protective effects on H 2 O 2 -induced H9c2 cells injury at the concentration of 25 μg/mL. And the protective effects of compound 1 was also investigated by the oxygen-glucose deprivation/reperfusion (OGD/R) tests.