Electroregulated Metal-Binding with a Crown Ether Tetrathiafulvalene Derivative: Toward Electrochemically Addressed Metal Cation Sponges.

PubMed

Le Derf, Franck; Mazari, Miloud; Mercier, Nicolas; Levillain, Eric; Richomme, Pascal; Becher, Jan; Garín, Javier; Orduna, Jesus; Gorgues, Alain; Sallé, Marc

1999-12-27

A redox responsive ligand incorporating the tetrathiafulvalene unit has been synthesized. The crystal structure of the free ligand (Z)-1 (C(20)H(30)O(5)S(8), triclinic P&onemacr;, Z = 2, a = 9.087(6) Å, b = 11.637(7) Å, c = 14.370(8) Å, alpha = 65.54(3) degrees, beta = 82.32(5) degrees, gamma = 84.18(6) degrees, V = 1368 Å(3)) shows the redox-active tetrathiafulvalene core to be essentially planar, which allows observation of two reversible one-electron processes upon electrochemical oxidation. The efficiency of this system in the control of the reversible complexation/expulsion sequence of a metallic cation (i.e., Ba(2+)) has been made possible thanks to a combination of (a) an unprecedented high coordination ability among tetrathiafulvalene-based macrocycles as determined by LSI mass spectrometry (log K degrees = 3.5, NBA-matrix) as well as by solution investigations ((1)H NMR and cyclic voltammetry titration studies), which remarkably converge to similar binding constant values (i.e., log K degrees = 4.2-4.3), and (b) reversible metal cation expulsion upon electrochemical oxidation to the dicationic state. A channel-like solid-state structure is observed for the Ba(2+) complex (C(20)H(30)O(5)S(8), Ba(2+)(CF(3)SO(3))(2)(2-), (H(2)O)(2), CD(3)CN, monoclinic C2/c, Z = 8, a = 45.66(1) Å, b = 8.897(5) Å, c = 23.124(8) Å, beta = 105.54(4) degrees, V = 9050 Å(3)), which results from the segregated stacking mode of the crown ether and the redox-active tetrathiafulvalene subunits, respectively.

Palladium-Catalyzed Reductive Insertion of Alcohols into Aryl Ether Bonds

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

Wang, Meng; Gutiérrez, Oliver Y.; Camaioni, Donald M.

Pd/C catalyzes C-O bond cleavage of aryl ethers (diphenyl ether and cyclohexyl phenyl ether) by methanol in H2. The aromatic C-O bond is cleaved by reductive methanolysis, which is initiated by Pd-catalyzed partial hydrogenation of one phenyl ring to form an enol ether. The enol ether reacts rapidly with methanol to form a ketal, which generates methoxycyclohexene by eliminating phenol or an alkanol. Subsequent hydrogenation leads to methoxycyclohexane.

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

4-Fluoro­anilinium tetra­chloridoferrate(III) 18-crown-6 clathrate

PubMed Central

Ge, Jia-Zhen; Zhao, Min-Min

2010-01-01

The reaction of 4-fluoro­aniline hydro­chloride, 18-crown-6 and ferric chloride in methano­lic solution yields the title compound, (C6H7FN)[FeCl4]·C12H24O6, which has an unusual supramolecular structure. N—H⋯O hydrogen-bonding inter­actions between the NH3 + substituents of the 4-fluoro­anilinium cations and the O atoms of the crown ether mol­ecules result in a rotator–stator-like structure. PMID:21587679

Crystal structures of dioxonium hexafluorotantalate and dioxonium hexafluoroniobate complexes with tetrabenzo-30-crown-10

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

Furmanova, N. G., E-mail: furm@ns.crys.ras.ru; Rabadanov, M. Kh.; Chernaya, T. S.

2008-03-15

Two isostructural complexes of dioxonium [H{sub 5}O{sub 2}]{sup +} with tetrabenzo-30-crown-10 of the compositions [(tetrabenzo-30-crown-10 {center_dot} H{sub 5}O{sub 2})][TaF{sub 6}] (I) and [(tetrabenzo-30-crown-10 {center_dot} H{sub 5}O{sub 2})][NbF{sub 6}] (II) are studied using X-ray diffraction. The complexes crystallize in the monoclinic crystal system (space group C2/c, Z = 4). The unit cell parameters of these compounds are as follows: a = 15.6583(12) Angstrom-Sign , b = 15.2259(13) Angstrom-Sign , c = 16.4473(13) Angstrom-Sign , and {beta} = 99.398(6) Degree-Sign for complex I and a = 15.7117(12) Angstrom-Sign , b = 15.2785(15) Angstrom-Sign , c = 16.5247(15) Angstrom-Sign , and {beta} =more » 99.398(7) Degree-Sign for complex II. These complexes belong to the ionic type. The dioxonium cation [H{sub 5}O{sub 2}]{sup +} in the form of the two-unit cluster [H{sub 3}O {center_dot} H{sub 2}O]{sup +} is stabilized by the strong hydrogen bond OH Midline-Horizontal-Ellipsis O [O Midline-Horizontal-Ellipsis O, 2.353(4) Angstrom-Sign ] and encapsulated by the crown ether. Each oxygen atom of the dioxonium cation also forms two oxygen bonds O Midline-Horizontal-Ellipsis O(crown). The crown ether adopts an unusual two-level (pocket-like) conformation, which provides a complete encapsulation of the oxonium associate. The interaction of the cationic complex with the anion in the crystal occurs through contacts of the C-H Midline-Horizontal-Ellipsis F type.« less

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.

Thermodynamic properties (enthalpy, bond energy, entropy, and heat capacity) and internal rotor potentials of vinyl alcohol, methyl vinyl ether, and their corresponding radicals.

PubMed

da Silva, Gabriel; Kim, Chol-Han; Bozzelli, Joseph W

2006-06-29

Vinyl alcohols (enols) have been discovered as important intermediates and products in the oxidation and combustion of hydrocarbons, while methyl vinyl ethers are also thought to occur as important combustion intermediates. Vinyl alcohol has been detected in interstellar media, while poly(vinyl alcohol) and poly(methyl vinyl ether) are common polymers. The thermochemical property data on these vinyl alcohols and methyl vinyl ethers is important for understanding their stability, reaction paths, and kinetics in atmospheric and thermal hydrocarbon-oxygen systems. Enthalpies , entropies , and heat capacities (C(p)()(T)) are determined for CH(2)=CHOH, C(*)H=CHOH, CH(2)=C(*)OH, CH(2)=CHOCH(3), C(*)H=CHOCH(3), CH(2)=C(*)OCH(3), and CH(2)=CHOC(*)H(2). Molecular structures, vibrational frequencies, , and C(p)(T) are calculated at the B3LYP/6-31G(d,p) density functional calculation level. Enthalpies are also determined using the composite CBS-Q, CBS-APNO, and G3 methods using isodesmic work reactions to minimize calculation errors. Potential barriers for internal rotors are calculated at the B3LYP/6-31G(d,p) level and used to determine the hindered internal rotational contributions to entropy and heat capacity. The recommended ideal gas phase values calculated in this study are the following (in kcal mol(-1)): -30.0, -28.9 (syn, anti) for CH(2)=CHOH; -25.6, -23.9 for CH(2)=CHOCH(3); 31.3, 33.5 for C(*)H=CHOH; 27.1 for anti-CH(2)=C(*)OH; 35.6, 39.3 for C(*)H=CHOCH(3); 33.5, 32.2 for CH(2)=C(*)OCH(3); 21.3, 22.0 for CH(2)=CHOC(*)H(2). Bond dissociation energies (BDEs) and group additivity contributions are also determined. The BDEs reveal that the O-H, O-CH(3), C-OH, and C-OCH(3) bonds in vinyl alcohol and methyl vinyl ether are similar in energy to those in the aromatic molecules phenol and methyl phenyl ether, being on average around 3 kcal mol(-1) weaker in the vinyl systems. The keto-enol tautomerization enthalpy for the interconversion of vinyl alcohol to acetaldehyde is determined to be -9.7 kcal mol(-1), while the activation energy for this reaction is calculated as 55.9 kcal mol(-1); this is the simplest keto-enol tautomerization and is thought to be important in the reactions of vinyl alcohol. Formation of the formyl methyl radical (vinoxy radical/vinyloxy radical) from both vinyl alcohol and methyl vinyl ether is also shown to be important, and its reactions are discussed briefly.

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.

N-alkyl pyrrolidone ether podands as versatile alkali metal ion chelants.

PubMed

Perrin, Andrea; Myers, Dominic; Fucke, Katharina; Musa, Osama M; Steed, Jonathan W

2014-02-28

This work explores the coordination chemistry of a bis(pyrrolidone) ether ligand. Pyrrolidones are commercially important functional groups because of the high polarity and hence high hydrophilicity and surface affinity. An array of alkali metal ion complexes of a podand bearing two pendant pyrrolidone functionalities, namely 1-{2-[2-(2-oxo-pyrrolid-1-yl)-ethoxy]-ethyl}-pyrrolid-2-one (1) are reported. Reaction of this ligand with sodium hexafluorophosphate gives two discrete species of formulae [Na(1)2]PF6 (3) and [Na3(H2O)2(μ-1)2](PF6)3 (4), and a coordination polymer {[Na3(μ3-1)3(μ2-1)](PF6)3}n (5). The same reaction in methanol gives a 1 : 1 complex, namely [Na2(μ-1)2(MeOH)2](PF6)2 (6). Use of tetraphenyl borate as a less coordinating counter ion gives [Na2(1)2(H2O)4](BPh4)2 (7) and [Na2(1)4](BPh4)2 (8). Two potassium complexes have also been isolated, a monomer [K(1)2]PF6 (9) and a cyclic tetramer [K4(μ4-H2O)2(μ-1)4](PF6)4 (10). The structures illustrate the highly polar nature of the amide carbonyl moiety within bis(pyrrolidone) ethers with longer interactions to the ether oxygen atom. The zinc complex is also reported and {[ZnCl2(μ-1)]}n (11) exhibits bonding only to the carbonyl moieties. The ether oxygen atom is not necessary for Na(+) complexation as exemplified by the structure of the sodium complex of the analogue 1,3-bis(pyrrolid-2-on-1-yl)butane (2). Reaction of compound 1 with lithium salts results in isolation of the protonated ligand.

Nanocomposites Derived from Carbon Nanofibers and a Hyperbranched Poly(Ether-Ketone): In Situ Polymerization, Chain-End Modification, and Properties (Preprint)

DTIC Science & Technology

2007-05-01

and Soxhlet - extracted with water for three days and methanol for three more days. It was then dried over P2O5 under reduced pressure at 120 °C...for 72 h to give the product in quantitative yield . Anal. Calcd. for C16.39H8O4: C, 73.22%; 6 H, 2.98%; O, 23.81%. Found: C, 72.94%; H, 3.12%; O...HBP-PEK)-g-VGCNF, 3e, to afford 0.47 (94% yield based on initial amount) of a black solid. Found: C, 98.66%; H, 0.93%; N, ɘ.20%; O, ɘ.10

Sensitive multiresidue method by HS-SPME/GC-MS for 10 volatile organic compounds in urine matrix: a new tool for biomonitoring studies on children.

PubMed

Antonucci, Arianna; Vitali, Matteo; Avino, Pasquale; Manigrasso, Maurizio; Protano, Carmela

2016-08-01

A HS-SPME method coupled with GC-MS analysis has been developed for simultaneously measuring the concentration of 10 volatile organic compounds (VOCs) (benzene, toluene, ethylbenzene, o-, m-, and p-xylene, methyl tert-butyl ether, ethyl tert-butyl ether, 2-methyl-2-butyl methyl ether, and diisopropyl ether) in urine matrix as a biomonitoring tool for populations at low levels of exposure to such VOCs. These compounds, potentially toxic for human health, are common contaminants of both outdoor and indoor air, as they are released by autovehicular traffic; some of them are also present in environmental tobacco smoke (ETS). Thus, the exposure to these pollutants cannot be neglected and should be assessed. The low limits of detection and quantification (LODs and LOQs <6.5 and 7.5 ng L(-1), respectively) and the high reproducibility (CVs <4 %) make the developed method suited for biomonitoring populations exposed at low levels such as children. Further, the method is cost-effective and low in time-consumption; therefore, it is useful for investigating large populations. It has been applied to children exposed to traffic pollution and/or ETS; the relevant results are reported, and the relevant implications are discussed.

[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.

Activation of C-O and C-C bonds and formation of novel HAlOH-ether complexes: an EPR study of the reaction of ground-state Al atoms with methylethyl ether and diethyl ether.

PubMed

Brunet, François D; Feola, Julie C; Joly, Helen A

2012-03-15

Reaction mixtures, containing Al atoms and methylethyl ether (MEE) or diethyl ether (DEE) in an adamantane matrix, were prepared with the aid of a metal-atom reactor known as a rotating cryostat. The EPR spectra of the resulting products were recorded from 77-260 K, at 10 K intervals. Al atoms were found to insert into methyl-O, ethyl-O, and C-C bonds to form CH(3)AlOCH(2)CH(3), CH(3)OAlCH(2)CH(3), and CH(3)OCH(2)AlCH(3), respectively, in the case of MEE while DEE produced CH(3)CH(2)AlOCH(2)CH(3) and CH(3)AlCH(2)OCH(2)CH(3), respectively. From the intensity of the transition lines attributed to the Al atom C-O insertion products of MEE, insertion into the methyl-O bond is preferred. The Al hyperfine interaction (hfi) extracted from the EPR spectra of the C-O insertion products was greater than that of the C-C insertion products, that is, 5.4% greater for the DEE system and 7% greater for the MEE system. The increase in Al hfi is thought to arise from the increased electron-withdrawing ability of the substituents bonded to Al. Besides HAlOH, resulting from the reaction of Al atoms with adventitious water, novel mixed HAlOH:MEE and HAlOH:DEE complexes were identified with the aid of isotopic studies involving H(2)(17)O and D(2)O. The Al and H hfi of HAlOH were found to decrease upon complex formation. These findings are consistent with the nuclear hfi calculated using a density functional theory (DFT) method with close agreement between theory and experiment occurring at the B3LYP level using a 6-311+G(2df,p) basis set.

4-(4-Meth­oxy­phen­yl)-2-methyl­but-3-yn-2-ol

PubMed Central

Eissmann, Frank; Kafurke, Uwe; Weber, Edwin

2010-01-01

The mol­ecular structure of the title compound, C12H14O2, features a nearly coplanar arrangement including the aromatic ring, the C C—C group and the ether O atom. The maximum deviation from the least-squares plane of these ten atoms is 0.0787 (8) Å for the ether O atom. In the crystal, mol­ecules are connected via O—H⋯O hydrogen bonds (involving the hy­droxy O atom both as hydrogen-bond donor and acceptor) and weaker (ar­yl)C—H⋯π(ar­yl) contacts, leading to the formation of strands running parallel to the b axis. Further stabilization results from weaker (meth­yl)C—H⋯π(acetyl­ene) inter­actions between different strands. PMID:21588063

Vibrational Signatures of Large Amplitude Motions for the Shackled Hydronium Ion Nested in 18-CROWN-6 Ether Using D2 Tagging

NASA Astrophysics Data System (ADS)

Duong, Chinh H.; Menges, Fabian; Craig, Stephanie; Wolke, Conrad T.; Johnson, Mark

2016-06-01

The diffuse spectra arising from the excess proton in dilute acids suggests that its behavior is highly dependent on the local environment surrounding it. In this work, we report how the spectra of the H3O+, NH4+, and CH3NH3+ ions respond when docked to the rigid, tri-coordinated binding pocket of the 18-crown-6 ether using cryogenic ion vibrational predissociation (CIVP) spectroscopy with D2 tagging at 10 K. The H3O+{tiny^bullet}18-crown-6 ether complex displays a broad (350 cm-1 FWHM) unstructured band arising from the OH stretching fundamentals, which is significantly broader than the corresponding band (125 cm-1 FWHM) in the Eigen cation (H9O4+) spectrum. Perdeuterated isotopologue studies for both systems yield sharper bands with clear multiplet structures, indicating that the broadening arises from nuclear quantum effects. The key displacements underlying this coupling were explored using the vibrationally adiabatic scheme introduced by McCoy in the context of similar broadening in the Ca2+OH-(H2O)n system. Christopher J. Johnson, Laura C. Dzugan, Arron B. Wolk, Christopher M. Leavitt, Joseph A. Fournier, Anne B. McCoy, Mark A. Johnson, J. Phys. Chem. A 118, 2014.

Health assessment of gasoline and fuel oxygenate vapors: micronucleus and sister chromatid exchange evaluations.

PubMed

Schreiner, Ceinwen A; Hoffman, Gary M; Gudi, Ramadevi; Clark, Charles R

2014-11-01

Micronucleus and sister chromatid exchange (SCE) tests were performed for vapor condensate of baseline gasoline (BGVC), or gasoline with oxygenates, methyl tert-butyl ether (G/MTBE), ethyl tert butyl ether (G/ETBE), t-amyl methyl ether (G/TAME), diisopropyl ether (G/DIPE), t-butyl alcohol (TBA), or ethanol (G/EtOH). Sprague Dawley rats (the same 5/sex/group for both endpoints) were exposed to 0, 2000, 10,000, or 20,000mg/m(3) of each condensate, 6h/day, 5days/week over 4weeks. Positive controls (5/sex/test) were given cyclophosphamide IP, 24h prior to sacrifice at 5mg/kg (SCE test) and 40mg/kg (micronucleus test). Blood was collected from the abdominal aorta for the SCE test and femurs removed for the micronucleus test. Blood cell cultures were treated with 5μg/ml bromodeoxyuridine (BrdU) for SCE evaluation. No significant increases in micronucleated immature erythrocytes were observed for any test material. Statistically significant increases in SCE were observed in rats given BGVC alone or in female rats given G/MTBE. G/TAME induced increased SCE in both sexes at the highest dose only. Although DNA perturbation was observed for several samples, DNA damage was not expressed as increased micronuclei in bone marrow cells. Inclusion of oxygenates in gasoline did not increase the effects of gasoline alone or produce a cytogenetic hazard. Copyright © 2014 Elsevier Inc. All rights reserved.

Supramolecular Recognition Allows Remote, Site-Selective C-H Oxidation of Methylenic Sites in Linear Amines.

PubMed

Olivo, Giorgio; Farinelli, Giulio; Barbieri, Alessia; Lanzalunga, Osvaldo; Di Stefano, Stefano; Costas, Miquel

2017-12-18

Site-selective C-H functionalization of aliphatic alkyl chains is a longstanding challenge in oxidation catalysis, given the comparable relative reactivity of the different methylenes. A supramolecular, bioinspired approach is described to address this challenge. A Mn complex able to catalyze C(sp 3 )-H hydroxylation with H 2 O 2 is equipped with 18-benzocrown-6 ether receptors that bind ammonium substrates via hydrogen bonding. Reversible pre-association of protonated primary aliphatic amines with the crown ether selectively exposes remote positions (C8 and C9) to the oxidizing unit, resulting in a site-selective oxidation. Remarkably, such control of selectivity retains its efficiency for a whole series of linear amines, overriding the intrinsic reactivity of C-H bonds, no matter the chain length. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Health assessment of gasoline and fuel oxygenate vapors: immunotoxicity evaluation.

PubMed

White, Kimber L; Peachee, Vanessa L; Armstrong, Sarah R; Twerdok, Lorraine E; Clark, Charles R; Schreiner, Ceinwen A

2014-11-01

Female Sprague Dawley rats were exposed via inhalation to vapor condensates of either gasoline or gasoline combined with various fuel oxygenates to assess potential immunotoxicity of evaporative emissions. Test articles included vapor condensates prepared from "baseline gasoline" (BGVC), or gasoline combined with methyl tertiary butyl ether (G/MTBE), ethyl t-butyl ether (G/ETBE), t-amyl methyl ether (G/TAME), diisopropyl ether (G/DIPE), ethanol (G/EtOH), or t-butyl alcohol (G/TBA). Target concentrations were 0, 2000, 10,000 or 20,000mg/mg(3) administered for 6h/day, 5days/week for 4weeks. The antibody-forming cell (AFC) response to the T-dependent antigen, sheep erythrocyte (sRBC), was used to determine the effects of the gasoline vapor condensates on the humoral components of the immune system. Exposure to BGVC, G/MTBE, G/TAME, and G/TBA did not result in significant changes in the IgM AFC response to sRBC, when evaluated as either specific activity (AFC/10(6) spleen cells) or as total spleen activity (AFC/spleen). Exposure to G/EtOH and G/DIPE resulted in a dose-dependent decrease in the AFC response, reaching the level of statistical significance only at the high 20,000mg/m(3) level. Exposure to G/ETBE resulted in a statistically significant decrease in the AFC response at the middle (10,000mg/m(3)) and high (20,000mg/m(3)) exposure concentrations. Copyright © 2014 Elsevier Inc. All rights reserved.

Additional chain-branching pathways in the low-temperature oxidation of branched alkanes

DOE PAGES

Wang, Zhandong; Zhang, Lidong; Moshammer, Kai; ...

2015-12-31

Chain-branching reactions represent a general motif in chemistry, encountered in atmospheric chemistry, combustion, polymerization, and photochemistry; the nature and amount of radicals generated by chain-branching are decisive for the reaction progress, its energy signature, and the time towards its completion. In this study, experimental evidence for two new types of chain-branching reactions is presented, based upon detection of highly oxidized multifunctional molecules (HOM) formed during the gas-phase low-temperature oxidation of a branched alkane under conditions relevant to combustion. The oxidation of 2,5-dimethylhexane (DMH) in a jet-stirred reactor (JSR) was studied using synchrotron vacuum ultra-violet photoionization molecular beam mass spectrometry (SVUV-PI-MBMS).more » Specifically, species with four and five oxygen atoms were probed, having molecular formulas of C 8H 14O 4 (e.g., diketo-hydroperoxide/keto-hydroperoxy cyclic ether) and C 8H 16O 5 (e.g., keto-dihydroperoxide/dihydroperoxy cyclic ether), respectively. The formation of C 8H 16O 5 species involves alternative isomerization of OOQOOH radicals via intramolecular H-atom migration, followed by third O 2 addition, intramolecular isomerization, and OH release; C 8H 14O 4 species are proposed to result from subsequent reactions of C 8H 16O 5 species. The mechanistic pathways involving these species are related to those proposed as a source of low-volatility highly oxygenated species in Earth's troposphere. At the higher temperatures relevant to auto-ignition, they can result in a net increase of hydroxyl radical production, so these are additional radical chain-branching pathways for ignition. Furthermore, the results presented herein extend the conceptual basis of reaction mechanisms used to predict the reaction behavior of ignition, and have implications on atmospheric gas-phase chemistry and the oxidative stability of organic substances.« less

Matrix isolation studies of the interactions of BF3 with water and substituted diethyl ethers. Chemical ionization mass spectrometric determination of the proton affinity of (CF3CH2)2O

NASA Technical Reports Server (NTRS)

Ball, David W.; Zehe, Michael J.

1993-01-01

BF3 was co-condensed with H2O, D2O, (C2H5)2O, (CF3CH2)2O, and (C2F5)2O in excess argon at 15 K. Infrared spectra of BF3/water isolated in solid argon provided a more complete analysis of the BF3--H2O complex than previously published. Infrared spectra of the matrices showed a definite Lewis acid-base interaction between BF3 and diethyl ether; a weak but definite interaction with bis (2,2,2-trifluorodiethyl) ether, and no observable interaction with perfluorodiethyl ether. Thus, the ether data indicate a clear trend between strength of interaction with BF3 and the degree of F substitution. To support and explain the emerging relationship between interaction strength and the basicity of the oxygen-containing molecule, the proton affinity of (CF3CH2)2O was measured using chemical ionization mass spectrometry. The implications of the results for lubricant/metal oxide surface interactions are discussed.

Crystal chemistry of elpidite from Khan Bogdo (Mongolia) and its K- and Rb-exchanged forms

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

Grigor'eva, A. A.; Zubkova, N. V., E-mail: nata_zubkova@rambler.ru; Pekov, I. V.

2011-09-15

Elpidite Na{sub 2}ZrSi{sub 6}O{sub 15} {center_dot} 3H{sub 2}O [space group Pbcm, a = 7.1312(12), b = 14.6853(12), and c = 14.6349(15) Angstrom-Sign ] from Khan Bogdo (Mongolia) and its K- and Rb-exchanged forms K{sub 1.78}Na{sub 0.16}H{sub 0.06}ZrSi{sub 6}O{sub 15} {center_dot} 0.85H{sub 2}O [Cmce, a = 14.054(3), b = 14.308(3), and c = 14.553(3) Angstrom-Sign ] and Na{sub 1.58}Rb{sub 0.2}H{sub 0.22}ZrSi{sub 6}O{sub 15} {center_dot} 2.69H{sub 2}O [Pbcm, a = 7.1280(10), b = 14.644(3), and c = 14.642(3) Angstrom-Sign ] that were obtained by cation exchange at 90 Degree-Sign C, as well as K{sub 1.84}Na{sub 0.11}H{sub 0.05}ZrSi{sub 6}O{sub 15} {center_dot} 0.91H{sub 2}Omore » [Cmce, a = 14.037(3), b = 14.226(3), and c = 14.552(3) Angstrom-Sign ] and Rb{sub 1.78}Na{sub 0.06}H{sub 0.16}ZrSi{sub 6}O{sub 15} {center_dot} 0.90H{sub 2}O [Cmce, a = 14.2999(12), b = 14.4408(15), and c = 14.7690(12) Angstrom-Sign ], obtained at 150 Degree-Sign C are studied by single-crystal X-ray diffraction and IR spectroscopy. The base of the structures is a heteropolyhedral Zr-Si-O framework whose cavities accommodate Na (K, Rb) cations and H{sub 2}O molecules.« less

Conformational Study of Dibenzyl Ether

NASA Astrophysics Data System (ADS)

Hernandez-Castillo, Alicia O.; Abeysekera, Chamara; Hewett, Daniel M.; Zwier, Timothy S.

2017-06-01

Understanding the initial stages of polycyclic aromatic hydrocarbon (PAH) aggregation, the onset of soot formation, is an important goal on the pathway to cleaner combustion processes. PAHs with short alkyl chains, present in fuel-rich combustion environments, can undergo reactions that will chemically link aromatic rings together. One such example of a linked diaryl compound is dibenzyl ether, C_{6}H_{5}-CH_{2}-O-CH_{2}-C_{6}H_{5}. The -CH_{2}-O-CH_{2}- linkage has a length and flexibility well-suited to forming a π-stacked conformation between the two phenyl rings. In this talk, we will explore the single-conformation spectroscopy of dibenzyl ether under jet-cooled conditions in the gas phase. Laser-induced fluorescence, chirped pulse Fourier transform microwave (8-18 GHz region), and single-conformation infrared spectroscopy in the alkyl CH stretch region were all carried out on the molecule, thereby interrogating its full array of electronic, vibrational and rotational degrees of freedom. This work is the first step in a broader study to determine the extent of π-stacking in linked aryl compounds as a function of linkage and PAH size.

Health assessment of gasoline and fuel oxygenate vapors: developmental toxicity in rats.

PubMed

Roberts, Linda G; Gray, Thomas M; Trimmer, Gary W; Parker, Robert M; Murray, F Jay; Schreiner, Ceinwen A; Clark, Charles R

2014-11-01

Gasoline-vapor condensate (BGVC) or condensed vapors from gasoline blended with methyl t-butyl ether (G/MTBE), ethyl t-butyl ether (G/ETBE), t-amyl methyl ether (G/TAME) diisopropyl ether (G/DIPE), ethanol (G/EtOH), or t-butyl alcohol (G/TBA) were evaluated for developmental toxicity in Sprague-Dawley rats exposed via inhalation on gestation days (GD) 5-20 for 6h/day at levels of 0 (control filtered air), 2000, 10,000, and 20,000mg/m(3). These exposure durations and levels substantially exceed typical consumer exposure during refueling (<1-7mg/m(3), 5min). Dose responsive maternal effects were reduced maternal body weight and/or weight change, and/or reduced food consumption. No significant malformations were seen in any study. Developmental effects occurred at 20,000mg/m(3) of G/TAME (reduced fetal body weight, increased incidence of stunted fetuses), G/TBA (reduced fetal body weight, increased skeletal variants) and G/DIPE (reduced fetal weight) resulting in developmental NOAEL of 10,000mg/m(3) for these materials. Developmental NOAELs for other materials were 20,000mg/m(3) as no developmental toxicity was induced in those studies. Developmental NOAELs were equal to or greater than the concurrent maternal NOAELs which ranged from 2000 to 20,000mg/m(3). There were no clear cut differences in developmental toxicity between vapors of gasoline and gasoline blended with the ether or alcohol oxygenates. Copyright © 2014 Elsevier Inc. All rights reserved.

a Comparison of the Molecular Structures of C_4H_9OCH_3, C_4H_9SCH_3, C_5H_{11}OCH_3, and C_5H_{11}SCH_3 Using Microwave Spectroscopy

NASA Astrophysics Data System (ADS)

Long, Brittany E.; Betancur, Juan; Choi, Yoon Jeong; Cooke, S. A.; Grubbs, G. S., II; Ogulnick, Jonathan; Holmes, Tara

2017-06-01

Pure rotational spectra of the title molecules have been recorded using chirped pulse Fourier transform microwave spectroscopy. Under our experimental conditions only one conformer has been observed for each of the four compounds. These conformers have torsional angles of CXCC = 180^o, XCCC = 60^o, CCCC = 180^o, and, for the C_5H_{11}-X-CH_3 species, CCCC_{Methyl} = 180^o. These angles correspond to anti-gauche-anti conformations for the butyl methyl ether/thioether species, and anti-gauche-anti-anti conformations for the pentyl methyl ether/thioether species. Splittings due to the internal rotation of the X-CH_3 group are observed in both butyl species but are not observed in the pentyl species. The barrier to the X-CH_3 internal rotation has been investigated through spectral analyses and quantum chemical calculations. The differences in the internal rotation barrier between the ethers and thioethers will be discussed and will further be compared to the barriers obtained for similar molecules.

[N,N-Bis(2,6-diisopropyl­phen­yl)pent-2-ene-2,4-diiminato(1−)]bis­(1,2,4-diaza­phosphol-1-yl)aluminium(III)

PubMed Central

Yang, Dongming; Pi, Chengfu; Ding, Yuqiang; Zheng, Wenjun

2010-01-01

In the title compound, [Al(C29H41N2)(C2H2N2P)2], the AlIII atom is coordinated by four N atoms from β-diketiminate and 1,2,4-diaza­phospho­lide ligands in a slightly distorted tetra­hedral fashion. PMID:21589338

Health assessment of gasoline and fuel oxygenate vapors: neurotoxicity evaluation.

PubMed

O'Callaghan, James P; Daughtrey, Wayne C; Clark, Charles R; Schreiner, Ceinwen A; White, Russell

2014-11-01

Sprague-Dawley rats were exposed via inhalation to vapor condensates of either gasoline or gasoline combined with various fuel oxygenates to assess potential neurotoxicity of evaporative emissions. Test articles included vapor condensates prepared from "baseline gasoline" (BGVC), or gasoline combined with methyl tertiary butyl ether (G/MTBE), ethyl t-butyl ether (G/ETBE), t-amyl methyl ether (G/TAME), diisopropyl ether (G/DIPE), ethanol (G/EtOH), or t-butyl alcohol (G/TBA). Target concentrations were 0, 2000, 10,000 or 20,000mg/mg(3) and exposures were for 6h/day, 5days/week for 13weeks. The functional observation battery (FOB) with the addition of motor activity (MA) testing, hematoxylin and eosin staining of brain tissue sections, and brain regional analysis of glial fibrillary acidic protein (GFAP) were used to assess behavioral changes, traditional neuropathology and astrogliosis, respectively. FOB and MA data for all agents, except G/TBA, were negative. G/TBA behavioral effects resolved during recovery. Neuropathology was negative for all groups. Analyses of GFAP revealed increases in multiplebrain regions largely limited to males of the G/EtOH group, findings indicative of minor gliosis, most significantly in the cerebellum. Small changes (both increases and decreases) in GFAP were observed for other test agents but effects were not consistent across sex, brain region or exposure concentration. Copyright © 2014 Elsevier Inc. All rights reserved.

Health assessment of gasoline and fuel oxygenate vapors: subchronic inhalation toxicity.

PubMed

Clark, Charles R; Schreiner, Ceinwen A; Parker, Craig M; Gray, Thomas M; Hoffman, Gary M

2014-11-01

Sprague Dawley rats were exposed via inhalation to vapor condensates of either gasoline or gasoline combined with various fuel oxygenates to assess whether their use in gasoline influences the hazard of evaporative emissions. Test substances included vapor condensates prepared from an EPA described "baseline gasoline" (BGVC), or gasoline combined with methyl tertiary butyl ether (G/MTBE), ethyl t-butyl ether (G/ETBE), t-amyl methyl ether (G/TAME), diisopropyl ether (G/DIPE), ethanol (G/EtOH), or t-butyl alcohol (G/TBA). Target concentrations were 0, 2000, 10,000 or 20,000mg/m(3) and exposures were for 6h/day, 5days/week for 13weeks. A portion of the animals were maintained for a four week recovery period to determine the reversibility of potential adverse effects. Increased kidney weight and light hydrocarbon nephropathy (LHN) were observed in treated male rats in all studies which were reversible or nearly reversible after 4weeks recovery. LHN is unique to male rats and is not relevant to human toxicity. The no observed effect level (NOAEL) in all studies was 10,000mg/m(3), except for G/MTBE (<2000) and G/TBA (2000). The results provide evidence that use of the studied oxygenates are unlikely to increase the hazard of evaporative emissions during refueling, compared to those from gasoline alone. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

Health assessment of gasoline and fuel oxygenate vapors: Neurotoxicity evaluation

PubMed Central

O’Callaghan, James P.; Daughtrey, Wayne C.; Clark, Charles R.; Schreiner, Ceinwen A.; White, Russell

2016-01-01

Sprague–Dawley rats were exposed via inhalation to vapor condensates of either gasoline or gasoline combined with various fuel oxygenates to assess potential neurotoxicity of evaporative emissions. Test articles included vapor condensates prepared from “baseline gasoline” (BGVC), or gasoline combined with methyl tertiary butyl ether (G/MTBE), ethyl t-butyl ether (G/ETBE), t-amyl methyl ether (G/TAME), diisopropyl ether (G/DIPE), ethanol (G/EtOH), or t-butyl alcohol (G/TBA). Target concentrations were 0, 2000, 10,000 or 20,000 mg/mg3 and exposures were for 6 h/day, 5 days/week for 13 weeks. The functional observation battery (FOB) with the addition of motor activity (MA) testing, hematoxylin and eosin staining of brain tissue sections, and brain regional analysis of glial fibrillary acidic protein (GFAP) were used to assess behavioral changes, traditional neuropathology and astrogliosis, respectively. FOB and MA data for all agents, except G/TBA, were negative. G/TBA behavioral effects resolved during recovery. Neuropathology was negative for all groups. Analyses of GFAP revealed increases in multiple brain regions largely limited to males of the G/EtOH group, findings indicative of minor gliosis, most significantly in the cerebellum. Small changes (both increases and decreases) in GFAP were observed for other test agents but effects were not consistent across sex, brain region or exposure concentration. PMID:24879970

TeX4 (X = F, Cl, Br) as Lewis acids--complexes with soft thio- and seleno-ether ligands.

PubMed

Hector, Andrew L; Jolleys, Andrew; Levason, William; Reid, Gillian

2012-08-28

TeF(4) reacts with OPR(3) (R = Me or Ph) in anhydrous CH(2)Cl(2) to give the colourless, square based pyramidal 1 : 1 complexes [TeF(4)(OPR(3))] only, in which the OPR(3) is coordinated basally in the solid state, (R = Me: d(Te-O) = 2.122(2) Å; R = Ph: d(Te-O) = 2.1849(14) Å). Variable temperature (19)F{(1)H}, (31)P{(1)H} and (125)Te{(1)H} NMR spectroscopic studies strongly suggest this is the low temperature structure in solution, although the systems are dynamic. The much softer donor ligands SMe(2) and SeMe(2) show a lower affinity for TeF(4), although unstable, yellow products with spectroscopic features consistent with [TeF(4)(EMe(2))] are obtained by the reaction of TeF(4) in neat SMe(2) or via reaction in CH(2)Cl(2) with SeMe(2). TeX(4) (X = F, Cl or Br) causes oxidation and halogenation of TeMe(2) to form X(2)TeMe(2). The Br(2)TeMe(2) hydrolyses in trace moisture to form [BrMe(2)Te-O-TeMe(2)Br], the crystal structure of which has been determined. TeX(4) (X = Cl or Br) react with the selenoethers SeMe(2), MeSe(CH(2))(3)SeMe or o-C(6)H(4)(SeMe)(2) (X = Cl) in anhydrous CH(2)Cl(2) to give the distorted octahedral monomers trans-[TeX(4)(SeMe(2))(2)], cis-[TeX(4){MeSe(CH(2))(3)SeMe}] and cis-[TeCl(4){o-C(6)H(4)(SeMe)(2)}], which have been characterised by IR, Raman and multinuclear NMR ((1)H, (77)Se{(1)H} and (125)Te{(1)H}) spectroscopy, and via X-ray structure determinations of representative examples. Tetrahydrothiophene (tht) can form both 1 : 1 and 1 : 2 Te : L complexes. For X = Br, the former has been shown to be a Br-bridged dimer, [Br(3)(tht)Te(μ-Br)(2)TeBr(3)(tht)], by crystallography with the tht ligands anti, whereas the latter are trans-octahedral monomers. Like its selenoether analogue, MeS(CH(2))(3)SMe forms distorted octahedral cis-chelates, [TeX(4){MeS(CH(2))(3)SMe}], whereas the more rigid o-C(6)H(4)(SMe)(2) unexpectedly forms a zig-zag chain polymer in the solid state, [TeCl(4){o-C(6)H(4)(SMe)(2)}](n), in which the dithioether adopts an extremely unusual bridging mode. This is in contrast to the chelating monomer, cis-[TeCl(4){o-C(6)H(4)(SeMe)(2)}], formed with the analogous selenoether and may be attributed to small differences in the ligand chelate bite angles. The wider bite angle xylyl-linked bidentates, o-C(6)H(4)(CH(2)EMe(2))(2) behave differently; the thioether forms cis-chelated [TeX(4){o-C(6)H(4)(CH(2)SMe)(2)}] confirmed crystallographically, whereas the selenoether undergoes C-Se cleavage and rearrangement on treatment with TeX(4), forming the cyclic selenonium salts, [C(9)H(11)Se](2)[TeX(6)]. The tetrathiamacrocycle, [14]aneS(4) (1,4,8,11-tetrathiacyclotetradecane), does not react cleanly with TeCl(4), but forms the very poorly soluble [TeCl(4)([14]aneS(4))](n), shown by crystallography to be a zig-zag polymer with exo-coordinated [14]aneS(4) units linked via alternate S atoms to a cis-TeCl(4) unit. Trends in the (125)Te{(1)H} NMR shifts for this series of Te(IV) halides chalcogenoether complexes are discussed.

Permitted Daily Exposure for Diisopropyl Ether as a Residual Solvent in Pharmaceuticals

PubMed Central

Evandri, Maria Grazia

2018-01-01

Solvents can be used in the manufacture of medicinal products provided their residual levels in the final product comply with the acceptable limits based on safety data. At worldwide level, these limits are set by the “Guideline Q3C (R6) on impurities: guideline for residual solvents” issued by the ICH. Diisopropyl ether (DIPE) is a widely used solvent but the possibility of using it in the pharmaceutical manufacture is uncertain because the ICH Q3C guideline includes it in the group of solvents for which “no adequate toxicological data on which to base a Permitted Daily Exposure (PDE) was found”. We performed a risk assessment of DIPE based on available toxicological data, after carefully assessing their reliability using the Klimisch score approach. We found sufficiently reliable studies investigating subchronic, developmental, neurological toxicity and carcinogenicity in rats and genotoxicity in vitro. Recent studies also investigated a wide array of toxic effects of gasoline/DIPE mixtures as compared to gasoline alone, thus allowing identifying the effects of DIPE itself. These data allowed a comprehensive toxicological evaluation of DIPE. The main target organs of DIPE toxicity were liver and kidney. DIPE was not teratogen and had no genotoxic effects, either in vitro or in vivo. However, it appeared to increase the number of malignant tumors in rats. Therefore, DIPE could be considered as a non-genotoxic animal carcinogen and a PDE of 0.98 mg/day was calculated based on the lowest No Observed Effect Level (NOEL) value of 356 mg/m3 (corresponding to 49 mg/kg/day) for maternal toxicity in developmental rat toxicity study. In a worst-case scenario, using an exceedingly high daily dose of 10 g/day, allowed DIPE concentration in pharmaceutical substances would be 98 ppm, which is in the range of concentration limits for ICH Q3C guideline class 2 solvents. This result might be considered for regulatory decisions. PMID:29686773

Di(phenylpropylamino)gossypol: a derivative of the dimeric natural product gossypol

USDA-ARS?s Scientific Manuscript database

Di(phenylpropylamino)gossypol [2,2'-bis(1,6-dihydroxy,-5-isopropyl,-8-methineaminopropylbenzene-3-methyl)-naphthylene-7-one, C48H52N2O6] is formed by reaction of the dimeric natural product gossypol with 3-phenyl-1-propylamine. When crystallized from diethyl ether, the compound has monoclinic (P21/c...

Ruthenium Catalyzed Diastereo- and Enantioselective Coupling of Propargyl Ethers with Alcohols: Siloxy-Crotylation via Hydride Shift Enabled Conversion of Alkynes to π-Allyls

PubMed Central

Liang, Tao; Zhang, Wandi; Chen, Te-Yu; Nguyen, Khoa D.; Krische, Michael J.

2015-01-01

The first enantioselective carbonyl crotylations through direct use of alkynes as chiral allylmetal equivalents are described. Chiral ruthenium(II) complexes modified by Josiphos (SL-J009-1) catalyze the C-C coupling of TIPS-protected propargyl ether 1a with primary alcohols 2a-2o to form products of carbonyl siloxy-crotylation 3a-3o, which upon silyl deprotection-reduction deliver 1,4-diols 5a-5o with excellent control of regio-, anti-diastereo- and enantioselectivity. Structurally related propargyl ethers 1b and 1c bearing ethyl- and phenyl-substituents engage in diastereo- and enantioselective coupling, as illustrated in the formation of adducts 5p and 5q, respectively. Selective mono-tosylation of diols 5a, 5c, 5e, 5f, 5k and 5m is accompanied by spontaneous cyclization to deliver the trans-2,3-disubstituted furans 6a, 6c, 6e, 6f, 6k and 6m, respectively. Primary alcohols 2a, 2l and 2p were converted to the siloxy-crotylation products 3a, 3l and 3p, which upon silyl deprotection-lactol oxidation were transformed to the trans-4,5-disubstituted γ-butyrolactones 7a, 7l and 7p. The formation of 7p represents a total synthesis of (+)-trans-whisky lactone. Unlike closely related ruthenium catalyzed alkyne-alcohol C-C couplings, deuterium labeling studies provide clear evidence of a novel 1,2-hydride shift mechanism that converts metal-bound alkynes to π-allyls in the absence of intervening allenes. PMID:26418572

H2O2 recycling during oxidation of the arylglycerol beta-aryl ether lignin structure by lignin peroxidase and glyoxal oxidase.

PubMed

Hammel, K E; Mozuch, M D; Jensen, K A; Kersten, P J

1994-11-15

Oxidative C alpha-C beta cleavage of the arylglycerol beta-aryl ether lignin model 1-(3,4-dimethoxy-phenyl)-2-phenoxypropane-1,3-diol (I) by Phanerochaete chrysosporium lignin peroxidase in the presence of limiting H2O2 was enhanced 4-5-fold by glyoxal oxidase from the same fungus. Further investigation showed that each C alpha-C beta cleavage reaction released 0.8-0.9 equiv of glycolaldehyde, a glyoxal oxidase substrate. The identification of glycolaldehyde was based on 13C NMR spectrometry of reaction product obtained from beta-, gamma-, and beta,gamma-13C-substituted I, and quantitation was based on an enzymatic NADH-linked assay. The oxidation of glycolaldehyde by glyoxal oxidase yielded 0.9 oxalate and 2.8 H2O2 per reaction, as shown by quantitation of oxalate as 2,3-dihydroxyquinoxaline after derivatization with 1,2-diaminobenzene and by quantitation of H2O2 in coupled spectrophotometric assays with veratryl alcohol and lignin peroxidase. These results suggest that the C alpha-C beta cleavage of I by lignin peroxidase in the presence of glyoxal oxidase should regenerate as many as 3 H2O2. Calculations based on the observed enhancement of LiP-catalyzed C alpha-C beta cleavage by glyoxal oxidase showed that approximately 2 H2O2 were actually regenerated per cleavage of I when both enzymes were present. The cleavage of arylglycerol beta-aryl ether structures by ligninolytic enzymes thus recycles H2O2 to support subsequent cleavage reactions.

Coordination trends in alkali metal crown ether uranyl halide complexes: the series [A(crown)]2[UO(2)X(4)] where A=Li, Na, K and X=Cl, Br.

PubMed

Danis, J A; Lin, M R; Scott, B L; Eichhorn, B W; Runde, W H

2001-07-02

UO(2)(C(2)H(3)O(2))(2).2H(2)O reacts with AX or A(C(2)H(3)O(2) or ClO(4)) (where A = Li, Na, K; X = Cl, Br) and crown ethers in HCl or HBr aqueous solutions to give the sandwich-type compounds [K(18-crown-6)](2)[UO(2)Cl(4)] (1), [K(18-crown-6)](2)[UO(2)Br(4)] (2), [Na(15-crown-5)](2)[UO(2)Cl(4)] (3), [Na(15-crown-5)](2)[UO(2)Br(4)] (4), [Li(12-crown-4)](2)[UO(2)Cl(4)] (5), and [Li(12-crown-4)](2)[UO(2)Br(4)] (6). The compounds have been characterized by single-crystal X-ray diffraction, powder diffraction, elemental analysis, IR, and Raman spectroscopy. The [UO(2)X(4)](2-) ions coordinate to two [A(crown)](+) cations through the four halides only (2), through two halides only (3), through the two uranyl oxygens and two halides (3, 4), or through the two uranyl oxygen atoms only (5, 6). Raman spectra reveal nu(U-O) values that correlate with expected trends. The structural trends are discussed within the context of classical principles of hard-soft acid-base theory.

Polymer-Nanoparticle Hybrid Photovoltaic Research for U.S. Air Force Applications

DTIC Science & Technology

2010-01-06

6 S S O S S O II xi xiviii xii (69%) (93%) (64%) (92%) 4S SBr Br S S OO OO II S S OO aReagents and Conditions: i.THF, n- BuLi , C6H13Br, -78oC, ii...CHCl3, FeCl3 (cat.), Br2, iii. THF, n- BuLi , B(OBu)3, -78oC, 2 M HCl, iv. Toluene, 1,3-propandiol, Reflux, v. (a) Ether, n- BuLi -78oC, (b) 3...thiophenecarboxaldehyde, vi. (a) n- BuLi (2eqiv.), -23oC, I2 (3eqiv.), (b) Na2SO3 and HI solun, vii. CH2Cl2, P.C.C, r.t, viii. Cu, DMF, Reflux, ix

Palladium-Catalyzed Formal Cross-Coupling of Diaryl Ethers with Amines: Slicing the 4-O-5 Linkage in Lignin Models.

PubMed

Zeng, Huiying; Cao, Dawei; Qiu, Zihang; Li, Chao-Jun

2018-03-26

Lignin is the second most abundant organic matter on Earth, and is an underutilized renewable source for valuable aromatic chemicals. For future sustainable production of aromatic compounds, it is highly desirable to convert lignin into value-added platform chemicals instead of using fossil-based resources. Lignins are aromatic polymers linked by three types of ether bonds (α-O-4, β-O-4, and 4-O-5 linkages) and other C-C bonds. Among the ether bonds, the bond dissociation energy of the 4-O-5 linkage is the highest and the most challenging to cleave. To date, 4-O-5 ether linkage model compounds have been cleaved to obtain phenol, cyclohexane, cyclohexanone, and cyclohexanol. The first example of direct formal cross-coupling of diaryl ether 4-O-5 linkage models with amines is reported, in which dual C(Ar)-O bond cleavages form valuable nitrogen-containing derivatives. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Conformation and Complexation of Tannins: NMR Spectra and Molecular Search Modeling of Flavan-3-ols

Treesearch

Richard W. Hemingway; Fred L. Tohiason; G. Wayne McGraw; Jan P. Steynberg

1996-01-01

Studies offlavan-3-01sin their biologically significant phenolic form show that both H-6 and C-6 resonances are downfield from H-8 and C-8. Therefore, assignments for the H atoms of the A-ring are inverse to those commonly reported. By contrast, in the methyl ether and methyl ether acetate derivatives, both H-8 and C-8 are downfield from H-6 and C-6 and assignments...

Design, synthesis, characterization, and OFET properties of amphiphilic heteroleptic tris(phthalocyaninato) europium(III) complexes. The effect of crown ether hydrophilic substituents.

PubMed

Gao, Yingning; Ma, Pan; Chen, Yanli; Zhang, Ying; Bian, Yongzhong; Li, Xiyou; Jiang, Jianzhuang; Ma, Changqin

2009-01-05

Two amphiphilic heteroleptic tris(phthalocyaninato) europium complexes with hydrophilic crown ether heads and hydrophobic octyloxy tails [Pc(mCn)(4)]Eu[Pc(mCn)(4)]Eu[Pc(OC(8)H(17))(8)] [m = 12, n = 4, H(2)Pc(12C4)(4) = 2,3,9,10,16,17,23,24-tetrakis(12-crown-4)phthalocyanine; m = 18, n = 6, H(2)Pc(18C6)(4) = 2,3,9,10,16,17,23,24-tetrakis(18-crown-6)phthalocyanine; H(2)Pc(OC(8)H(17))(8) = 2,3,9,10,16,17,23,24-octakis(octyloxy)phthalocyanine] (1, 2) were designed and prepared from the reaction between homoleptic bis(phthalocyaninato) europium compound [Pc(mCn)(4)]Eu[Pc(mCn)(4)] (m = 12, n = 4; m = 18, n = 6) and metal-free H(2)Pc(OC(8)H(17))(8) in the presence of Eu(acac)(3).H(2)O (Hacac = acetylacetone) in boiling 1,2,4-trichlorobenzene. These novel sandwich triple-decker complexes were characterized by a wide range of spectroscopic methods and electrochemically studied. With the help of the Langmuir-Blodgett technique, these typical amphiphilic triple-decker complexes were fabricated into organic field effect transistors (OFET) with top contact configuration on bare SiO(2)/Si substrate, hexamethyldisilazane-treated SiO(2)/Si substrate, and octadecyltrichlorosilane (OTS)-treated SiO(2)/Si substrate, respectively. The device performance is revealed to be dependent on the species of crown ether substituents and substrate surface treatment. OFETs fabricated from the triple decker with 12-crown-4 hydrophilic substituents, 1, allow the hole transfer in the direction parallel to the aromatic phthalocyanine rings. In contrast, the devices of a triple-decker compound containing 18-crown-6 as hydrophilic heads, 2, transfer holes in a direction along the long axis of the assembly composed of face-to-face aggregated triple-decker molecules, revealing the effect of molecular structure, specifically the crown ether substituents on the film structure and OFET functional properties. The carrier mobility for hole as high as 0.33 cm(2) V(-1) s(-1) and current modulation of 7.91 x 10(5) were reached for the devices of triple-decker compound 1 deposited on the OTS-treated SiO(2)/Si substrates, indicating the effect of substrate surface treatment on the OFET performance due to the improvement on the film quality as demonstrated by the atomic force microscope investigation results.

Di-μ-bromido-bis-[(diethyl ether-κO)(2,4,6-tri-methyl-phen-yl)magnesium]: the mesityl Grignard reagent.

PubMed

Seven, Omer; Bolte, Michael; Lerner, Hans-Wolfram

2013-01-01

The crystal structure of the title compound, [Mg2Br2(C9H11)2(C4H10O)2], features a centrosymmetric two-centre magnesium complex with half a mol-ecule in the asymmetric unit. The Mg atom is in a considerably distorted Br2CO coordination. Bond lengths and angles are comparable with already published values. The crystal packing is stabilized by C-H⋯π inter-actions linking the complexes into sheets parallel to (0-11).

Synthesis of Improved Antileishmanial and Antitrypanosomal Drugs Treatment and Prophylaxis

DTIC Science & Technology

1986-11-01

for a diphenyl ether analog ((2) p. 44). 16 - -r , ü$$m&±ysc$c .<v£*^Ä VV’-Orfs aB9*>ratfe>^v CHART NO. 1 8-[(6-AMIDOXIMINOHEXYL)AMINO]-6-METHOXY...MALEATE (SNL-130) cico—(f)V-ci A1C1 CS 1 (58%) • Brü 1) »3PCH2CH2NMe2/n-BuLi 2) H30* 3) Oxalic Acid 4) OH 0 «CHCH,NMe 2ŕ,c2 2 (79%), Free base... diphenyl ether analog ((2) p. 44). A mixture of sodium amide (11.6 g, O.J mol), acetonitrile (15 mL, 11.8 g> 0.29 mol) and dry benzene (1 L) was heated

Isopycnic Phases and Structures in H2O/CO2/Ethoxylated Alcohol Surfactant Mixtures

NASA Technical Reports Server (NTRS)

Paulaitis, Michael E.; Zielinski, Richard G.; Kaler, Eric W.

1996-01-01

Ternary mixtures of H2O and CO2 with ethoxylated alcohol (C(i)E(j)) surfactants can form three coexisting liquid phases at conditions where two of the phases have the same density (isopycnic phases). Isopycnic phase behavior has been observed for mixtures containing the surfactants C8E5, C10E6, and C12E6, but not for those mixtures containing either C4E1 or CgE3. Pressure-temperature (PT) projections for this isopycnic three-phase equilibrium were determined for H2O/CO2/C8E5 and H2O/CO2/C10E6 mixtures at temperatures from approximately 25 to 33 C and pressures between 90 and 350 bar. As a preliminary to measuring the microstructure in isopycnic three component mixtures, phase behavior and small angle neutron scattering (SANS) experiments were performed on mixtures of D2O/CO2/ n-hexaethyleneglycol monododecyl ether (C12E6) as a function of temperature (25-31 C), pressure (63.1-90.7 bar), and CO2 composition (0-3.9 wt%). Parameters extracted from model fits of the SANS spectra indicate that, while micellar structure remains essentially unchanged, critical concentration fluctuations increase as the phase boundary and plait point are approached.

Hydrogen-bonded supramolecular structures of three related 4-(5-nitro-2-furyl)-1,4-dihydropyridines.

PubMed

Quesada, Antonio; Argüello, Jacqueline; Squella, Juan A; Wardell, James L; Low, John N; Glidewell, Christopher

2006-01-01

In ethyl 5-cyano-2,6-dimethyl-4-(5-nitro-2-furyl)-1,4-dihydropyridine-3-carboxylate, C15H15N3O5, the molecules are linked into chains by a single N-H...O hydrogen bond. The molecules in diethyl 2,6-dimethyl-4-(5-nitro-2-furyl)-1,4-dihydropyridine-3,5-dicarboxylate, C17H20N2O7, are linked by a combination of one N-H...O hydrogen bond and two C-H...O hydrogen bonds into sheets built from equal numbers of R(2)(2)(17) and R(4)(4)(18) rings. In 2,6-dimethyl-4-(5-nitro-2-furyl)-1,4-dihydropyridine-3,5-dicarbonitrile, C13H10N4O3, the molecules are linked by a combination of a three-centre N-H...(O)2 hydrogen bond and two independent two-centre C-H...O hydrogen bonds into complex sheets containing four types of ring.

Health assessment of gasoline and fuel oxygenate vapors: reproductive toxicity assessment.

PubMed

Gray, Thomas M; Steup, David; Roberts, Linda G; O'Callaghan, James P; Hoffman, Gary; Schreiner, Ceinwen A; Clark, Charles R

2014-11-01

Vapor condensates of baseline gasoline (BGVC), or gasoline-blended with methyl tertiary butyl ether (G/MTBE), ethyl t-butyl ether (G/ETBE), t-amyl methyl ether (G/TAME), diisopropyl ether (G/DIPE), ethanol (G/EtOH), or t-butyl alcohol (G/TBA) were evaluated for reproductive toxicity in rats at target concentrations of 2000, 10,000, or 20,000mg/m(3), 6h/day, 7days/week. BGVC and G/MTBE were assessed over two generations, the others for one generation. BGVC and G/MTBE F1 offspring were evaluated for neuropathology and changes in regional brain glial fibrillary acidic protein content. No neurotoxicity was observed. Male kidney weight was increased consistent with light hydrocarbon nephropathy. In adult rats, decreased body weight gain and increased liver weight were seen. Spleen weight decreased in adults and pups exposed to G/TBA. No pathological changes to reproductive organs occurred in any study. Decreased food consumption was seen in G/TAME lactating females. Transient decreases in G/TAME offspring weights were observed during lactation. Except for a minor increase in time to mating in G/TBA which did not affect other reproductive parameters, there were no adverse reproductive findings. The NOAEL for reproductive and offspring parameters was 20,000mg/m(3) for all vapor condensates except for lower offspring NOAELs of 10,000mg/m(3) for G/TBA and 2000mg/m(3) for G/TAME. Copyright © 2014 Elsevier Inc. All rights reserved.

Health assessment of gasoline and fuel oxygenate vapors: Reproductive toxicity assessment

PubMed Central

Gray, Thomas M.; Steup, David; Roberts, Linda G.; O'Callaghan, James P.; Hoffman, Gary; Schreiner, Ceinwen A.; Clark, Charles R.

2016-01-01

Vapor condensates of baseline gasoline (BGVC), or gasoline-blended with methyl tertiary butyl ether (G/MTBE), ethyl t-butyl ether (G/ETBE), t-amyl methyl ether (G/TAME), diisopropyl ether (G/DIPE), ethanol (G/EtOH), or t-butyl alcohol (G/TBA) were evaluated for reproductive toxicity in rats at target concentrations of 2000, 10,000, or 20,000 mg/m3, 6 h/day, 7 days/week. BGVC and G/MTBE were assessed over two generations, the others for one generation. BGVC and G/MTBE F1 offspring were evaluated for neuropathology and changes in regional brain glial fibrillary acidic protein content. No neurotoxicity was observed. Male kidney weight was increased consistent with light hydrocarbon nephropathy. In adult rats, decreased body weight gain and increased liver weight were seen. Spleen weight decreased in adults and pups exposed to G/TBA. No pathological changes to reproductive organs occurred in any study. Decreased food consumption was seen in G/TAME lactating females. Transient decreases in G/TAME off-spring weights were observed during lactation. Except for a minor increase in time to mating in G/TBA which did not affect other reproductive parameters, there were no adverse reproductive findings. The NOAEL for reproductive and offspring parameters was 20,000 mg/m3 for all vapor condensates except for lower offspring NOAELs of 10,000 mg/m3 for G/TBA and 2000 mg/m3 for G/TAME. PMID:24813181

Synthesis of Soluble Alpha-Thiophene Oligomers. Monomer to Octamer

DTIC Science & Technology

1992-04-25

by forming the Grignard reagent of 5 [Mg (1.5 3 Schemne I a... Me3Si- -SMe 3 (1 1 2 Brj3-B ----m MeSi- 4 j 3 -- X d~-e me3Si J- SiW 3 (2) 3 4, X =Br 6...1.03 equiv), C6 H6 , 0* C to 230 C, 0.5 h, 94 %] and then to the corresponding Grignard reagent [Mg (1.5 equiv), ether, 23*C to 350 C] which was...PPh3)4 (5 mol %), toluene, reflux, 14 h] afforded the pentamer 1 in 47 % yield (eq g).25 The Grignard reagent of 13 was coupled with the iodide 16

Ionic complexation of N 2O 4 by 18-crown-6

NASA Astrophysics Data System (ADS)

Ricard, S.; Audet, P.; Savoie, R.

1988-08-01

An ionic complex has been obtained from N 2O 4 in the presence of the macrocyclic ether 18-crown-6. This crystalline compound has been shown from its Raman spectrum to have the formula NO +·crown·H(NO 3) 2-, with the nitrosonium ion closely associated with the crown ether rather than with the hydrogen dinitrate accompanying ion. This adduct decomposes readily in moist air to give the known complex (HNO 3·H 2O) 2·crown.

Experimental and Calculational Studies of the Interactions of BF3 with Fluoroethers

NASA Technical Reports Server (NTRS)

Zehe, Michael J.; Morales, Wilfredo; Ball, David W.

1998-01-01

BF3 was co-condensed with (C2H5)2O, (CF3CH2)2O and (C2F5)2O in excess argon at 15 K. Infrared spectra of the matrices showed a definite Lewis acid-base interaction between BF3 and diethyl ether; a weak but definite interaction with bis(2,2,2,-trifluorodiethyl)ether, and no observable interaction with perfluorodiethyl ether. Molecular orbital (MO) calculations complemented the experimental observations by revealing that fluorine atoms on the ethers decreased electron localization about the oxygen atom. Thus, the experimental data and MO calculations indicated a clear trend between strength of interaction with BF3 and the degree of ether F substitution. The implications of the results for commercial perfluoro ether lubricant/metal oxide surface interactions are discussed.

Synthesis and electronic factors in thermal cyclodimerization of functionalized aromatic trifluorovinyl ethers.

PubMed

Spraul, Bryan K; Suresh, S; Jin, Jianyong; Smith, Dennis W

2006-05-31

A series of 19 p-substituted aromatic trifluorovinyl ether compounds were prepared from versatile intermediate p-Br-C(6)H(4)-O-CF=CF(2) and underwent thermal radical mediated cyclodimerization to new difunctional compounds containing the 1,2-disubstituted perfluorocyclobutyl (PFCB) linkage. The synthetic scope demonstrates the functional group transformation tolerance of the fluorovinyl ether, and the dimers are useful as monomers for traditional step-growth polymerization methods. (19)F NMR spectra confirmed that p-substitution affects the trifluorovinyl ether group chemical shifts. The first kinetic studies and substituent effects on thermal cyclodimerization were performed, and the results indicated that electron-withdrawing groups slow the rate of cyclodimerization. The data were further analyzed using the Hammett equation, and reaction constants (rho) of -0.46 at 120 degrees C and -0.59 at 130 degrees C were calculated. This study presents the first liner free energy relationship reported for the cyclodimerization of aromatic trifluorovinyl ethers to PFCB compounds.

Gibbs energies of transferring triglycine from water into H2O-DMSO solvent

NASA Astrophysics Data System (ADS)

Usacheva, T. R.; Kuz'mina, K. I.; Lan, Pham Thi; Kuz'mina, I. A.; Sharnin, V. A.

2014-08-01

The Gibbs energies of transferring triglycine (3Gly, glycyl-glycyl-glycine) from water into mixtures of water with dimethyl sulfoxide (χDMSO = 0.05, 0.10, and 0.15 mole fractions) at 298.15 K are determined from the interphase distribution. An increased dimethyl sulfoxide (DMSO) concentration in the solvent slightly raises the positive values of Δtr G ○(3Gly), possibly indicating the formation of more stable 3Gly-H2O solvated complexes than ones of 3Gly-DMSO. It is shown that the change in the Gibbs energy of transfer of 3Gly is determined by the enthalpy component. The relationship of 3Gly and 18-crown-6 ether (18C6) solvation's contributions to the change in the Gibbs energy of [3Gly18C6] molecular complex formation in H2O-DMSO solvents is analyzed, and the key role of 3Gly solvation's contribution to the change in the stability of [3Gly18C6] upon moving from H2O to mixtures with DMSO is revealed.

(1RS,4SR)-3-Dichloro­methyl­ene-1,4-dimethyl-2-oxabicyclo­[2.2.2]oct-5-ene

PubMed Central

Tyrrell, Andrew J.; Feast, George C.; Robertson, Jeremy

2008-01-01

X-ray crystallography was used to confirm the structure of the enantio-enriched title compound, C10H12Cl2O, a bicylic enol ether. A bridged boat-like structure is adopted and the dichloro­methyl­ene C atom is positioned significantly removed from the core bicyclic unit. In the crystal structure, mol­ecules pack to form sheets approximately perpendicular to the a and c axes. PMID:21202895

α-Diazo oxime ethers for N-heterocycle synthesis.

PubMed

Choi, Subin; Ha, Sujin; Park, Cheol-Min

2017-06-01

This Feature Article introduces the preparation and synthetic utility of α-diazo oxime ethers. α-Oximino carbenes are useful synthons for N-heterocycles, and can be easily prepared from α-diazo oxime ethers as precursors. We begin with the preparation of α-diazo oxime ethers and their application in [3+2] cycloaddition. It turns out that the nature of metals bound to carbenes plays a crucial role in modulating the reactivity of α-oximino carbenes, in which copper carbenes smoothly react with enamines, whereas the less reactive enol ethers and nitriles require gold carbenes. In Section 3.2, a discussion on N-O and C-H bond activation is presented. Carbenes derived from diazo oxime ethers show unique reactivity towards N-O and C-H bond activation, in which the proximity of the two functionalities, carbene and oxime ether, dictates the preferred reaction pathways toward pyridines, pyrroles, and 2H-azirines. In Section 3.3, the development of tandem reactions based on α-diazo oxime ethers is discussed. The nature of carbenes in which whether free carbenes or metal complexes are involved dissects the pathway and forms different types of 2H-azirines. The 2H-azirine formation turned out to be an excellent platform for the tandem synthesis of N-heterocycles including pyrroles and pyridines. In the last section, we describe the electrophilic activation of 2H-azirines with vinyl carbenes and oximino carbenes. The resulting azirinium species undergo rapid ring expansion rearrangements to form pyridines and pyrazines.

VAPOR PRESSURES, LIQUID MOLAR VOLUMES, VAPOR NON- IDEALITIES, AND CRITICAL PROPERTIES OF SOME FLUORINATED ETHERS: CF3OCF2OCF3, CF3OCF2 CF2H, c-CF2CF2CF2O, CF3OCF2H, AND CF3OCH3; AND OF CCl3F AND CF2ClH

EPA Science Inventory

Vapor pressures, compressibilities, expansivities, and molar volumes of the liquid phase have been measured between room temperature and the critical temperature for a series of fluorinated ethers: CF3OCF2OCF3, CF3OCF2CF2H, c-CF2CF2CF2O, CF3OCF2H, and CF3OCH3. Vapor-phase non-ide...

Crystal structures of complexes of the cys-syn-cys isomer of dicyclohexano-18-crown-6 with oxonium hexafluorotantalate and oxonium hexafluoroniobate

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

Fonari, M. S.; Alekseeva, O. A.; Furmanova, N. G.

2007-03-15

The crystal structures of [(cys-syn-cys-dicyclohexano-18-crown-6 . H{sub 3}O)][TaF{sub 6}] and [(cys-syn-cys-dicyclohexano-18-crown-6 . H{sub 3}O)][NbF{sub 6}] complex compounds are determined using X-ray diffraction analysis. The tantalum complex has two polymorphic modifications, namely, the monoclinic (I) and triclinic (II) modifications. The unit cell parameters of these compounds are as follows: a = 8.507(4) A, b = 11.947(5) A, c = 27.392(12) A, {beta} = 93.11(1) deg., Z = 4, and space group P2{sub 1}/n for modification I; and a = 10.828(1) A, b = 11.204(1) A, c = 12.378(1) A, {alpha} = 72.12(1) deg., {beta} = 79.40(1) deg., {gamma} = 73.70(1) deg.,more » Z = 2, and space group P-1 for modification II. The triclinic niobium complex [(cys-syn-cys-dicyclohexano-18-crown-6 . H{sub 3}O)][NbF{sub 6}] (III) with the unit cell parameters a = 10.796(3) A, b = 11.183(3) A, c = 12.352(3) A, {alpha} = 72.364(5) deg., {beta} = 79.577(5) deg., {gamma} = 73.773(4) deg., Z = 2, and space group P-1 is isostructural with tantalum complex II. The structures of all three complexes are ionic in character. The oxonium cation in complexes I-III is encapsulated by the crown ether and thus forms one ordinary and two bifurcated hydrogen bonds with the oxygen atoms of the crown ether. This macrocyclic cation is bound to the anions through the C-H...F contacts (H...F, 2.48-2.58 A). The conformation of the macrocycle in complex I differs substantially from that in complex II (III)« less

Lipase-catalyzed kinetic resolution of novel antitubercular benzoxazole derivatives.

PubMed

Łukowska-Chojnacka, Edyta; Kowalkowska, Anna; Napiórkowska, Agnieszka

2018-04-01

Novel benzoxazole derivatives were synthesized, and their antitubercular activity against sensitive and drug-resistant Mycobacterium tuberculosis strains (M. tuberculosis H 37 Rv, M. tuberculosis sp. 210, M. tuberculosis sp. 192, Mycobacterium scrofulaceum, Mycobacterium intracellulare, Mycobacterium fortuitum, Mycobacterium avium, and Mycobacterium kansasii) was evaluated. The chemical step included preparation of ketones, alcohols, and esters bearing benzoxazole moiety. All racemic mixtures of alcohols and esters were separated in Novozyme SP 435-catalyzed transesterification and hydrolysis, respectively. The transesterification reactions were carried out in various organic solvents (tert-butyl methyl ether, toluene, diethyl ether, and diisopropyl ether), and depending on the solvent, the enantioselectivity of the reactions ranged from 4 to >100. The enzymatic hydrolysis of esters was performed in 2 phase tert-butyl methyl ether/phosphate buffer (pH = 7.2) system and provided also enantiomerically enriched products (ee 88-99%). The antitubercular activity assay has shown that synthesized compounds exhibit an interesting antitubercular activity. Racemic mixtures of alcohols, (±)-4-(1,3-benzoxazol-2-ylsulfanyl)butan-2-ol ((±)-3a), (±)-4-[(5-bromo-1,3-benzoxazol-2-yl)sulfanyl]butan-2-ol ((±)-3b), and (±)-4-[(5,7-dibromo-1,3-benzoxazol-2-yl)sulfanyl]butan-2-ol ((±)-3c), displayed as high activity against M. scrofulaceum, M. intracellulare, M. fortuitum, and M. kansasii as commercially available antituberculosis drug-Isoniazid. Moreover, these compounds exhibited twice higher activity toward M. avium (MIC 12.5) compared with Isoniazid (MIC 50). © 2017 Wiley Periodicals, Inc.

Anti-knock quality of sugar derived levulinic esters and cyclic ethers

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

Tian, Miao; McCormick, Robert L.; Luecke, Jon

Here, the objective of this paper is to investigate the anti-knock quality of sugar-derived levulinic esters (methyl levulinate (ML) and ethyl levulinate (EL)) and cyclic ethers (furfuryl ethyl ether (FEE) and ethyl tetrahydrofurfuryl ether (ETE)). To this end, combustion experiments were carried out in both an engine and a constant volume autoignition device. The results from both apparati demonstrate that ML, EL and FEE have superior anti-knock quality than the reference Euro95 gasoline. ETE, conversely, performed markedly worse than the reference fuel on both setups and might therefore be a more appropriate fuel for compression ignition engines. The main reasonmore » of the distinctions in anti-knock quality can be found in the molecular structure of the neat biofuels. ML and EL are levulinic esters, with a ketone (C=O) functionality and an ester (C(=O)-O) group on the carbon chain. They can readily produce stable intermediates during the auto-ignition process, thereby slowing down the overall reaction rate. The unsaturated cyclic ether (FEE) has very strong ring C-H bonds. However, the saturated cyclic ether (ETE) has weak ring C-H bonds, which facilitate more readily ring opening reactions. Long side chains on the cyclic ethers further accelerate the reaction rate. Importantly for future research, our results suggest that IQT and engine experiments are interchangeable setups with respect to qualitative anti-knock quality evaluation of novel compounds.« less

Anti-knock quality of sugar derived levulinic esters and cyclic ethers

DOE PAGES

Tian, Miao; McCormick, Robert L.; Luecke, Jon; ...

2017-04-22

Here, the objective of this paper is to investigate the anti-knock quality of sugar-derived levulinic esters (methyl levulinate (ML) and ethyl levulinate (EL)) and cyclic ethers (furfuryl ethyl ether (FEE) and ethyl tetrahydrofurfuryl ether (ETE)). To this end, combustion experiments were carried out in both an engine and a constant volume autoignition device. The results from both apparati demonstrate that ML, EL and FEE have superior anti-knock quality than the reference Euro95 gasoline. ETE, conversely, performed markedly worse than the reference fuel on both setups and might therefore be a more appropriate fuel for compression ignition engines. The main reasonmore » of the distinctions in anti-knock quality can be found in the molecular structure of the neat biofuels. ML and EL are levulinic esters, with a ketone (C=O) functionality and an ester (C(=O)-O) group on the carbon chain. They can readily produce stable intermediates during the auto-ignition process, thereby slowing down the overall reaction rate. The unsaturated cyclic ether (FEE) has very strong ring C-H bonds. However, the saturated cyclic ether (ETE) has weak ring C-H bonds, which facilitate more readily ring opening reactions. Long side chains on the cyclic ethers further accelerate the reaction rate. Importantly for future research, our results suggest that IQT and engine experiments are interchangeable setups with respect to qualitative anti-knock quality evaluation of novel compounds.« less

Cationic Bulk Polymerization of Vinyl Ethers in the Liquid Crystalline Phase

DTIC Science & Technology

1991-10-30

mesophase, if any, cannot alone be responsible for the unusual results obtained in this study. Table 3 . Polymerization of’ 2 -[(4-cyano-4’-biphenvl)oxy...NCC 11-H-( /C20 \\ / z 0 h ab cd e f S(7.43-7.47) Li (1.27-1.73) d (6.88-6.93) ab(7.53-7.64) ( 3 8 - , 4 9 h ( 3 .4 4 ) 10 9 8 7 6 5 4 3 2 1 0 Figure...Macromol. Sci.-Rev. Makromol. Chem. 171, 137 (1979) 2 . C. M. Paleos, Chem. Soc. Rev. 14, 45 (1985) 3 . R. G. Weiss, Tetrahedron 44, 3413 (1988) 4. D. J

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.

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

Interstellar Aldehydes and their corresponding Reduced Alcohols: Interstellar Propanol?

NASA Astrophysics Data System (ADS)

Etim, Emmanuel; Chakrabarti, Sandip Kumar; Das, Ankan; Gorai, Prasanta; Arunan, Elangannan

2016-07-01

There is a well-defined trend of aldehydes and their corresponding reduced alcohols among the known interstellar molecules; methanal (CH_2O) and methanol (CH_3OH); ethenone (C_2H_2O) and vinyl alcohol (CH_2CHOH); ethanal (C_2H_4O) and ethanol(C_2H_5OH); glycolaldehyde (C_2H_4O_2) and ethylene glycol(C_2H_6O_2). The reduced alcohol of propanal (CH_3CH_2CHO) which is propanol (CH_3CH_2CH_2OH) has not yet been observed but its isomer; ethyl methyl ether (CH_3CH_2OCH_3) is a known interstellar molecule. In this article, different studies are carried out in investigating the trend between aldehydes and their corresponding reduced alcohols and the deviation from the trend. Kinetically and with respect to the formation route, alcohols could have been produced from their corresponding reduced aldehydes via two successive hydrogen additions. This is plausible because of (a) the unquestionable high abundance of hydrogen, (b) presence of energy sources within some of the molecular clouds and (c) the ease at which successive hydrogen addition reaction occurs. In terms of stability, the observed alcohols are thermodynamically favorable as compared to their isomers. Regarding the formation process, the hydrogen addition reactions are believed to proceed on the surface of the interstellar grains which leads to the effect of interstellar hydrogen bonding. From the studies, propanol and propan-2-ol are found to be more strongly attached to the surface of the interstellar dust grains which affects its overall gas phase abundance as compared to its isomer ethyl methyl ether which has been observed.

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.

Scandium complexes with the tetraphenylethylene and anthracene dianions.

PubMed

Ellis, John E; Minyaev, Mikhail E; Nifant'ev, Ilya E; Churakov, Andrei V

2018-06-01

The structural study of Sc complexes containing dianions of anthracene and tetraphenylethylene should shed some light on the nature of rare-earth metal-carbon bonding. The crystal structures of (18-crown-6)bis(tetrahydrofuran-κO)sodium bis(η 6 -1,1,2,2-tetraphenylethenediyl)scandium(III) tetrahydrofuran disolvate, [Na(C 4 H 8 O) 2 (C 12 H 24 O 6 )][Sc(C 26 H 20 ) 2 ]·2C 4 H 8 O or [Na(18-crown-6)(THF) 2 ][Sc(η 6 -C 2 Ph 4 ) 2 ]·2(THF), (1b), (η 5 -1,3-diphenylcyclopentadienyl)(tetrahydrofuran-κO)(η 6 -1,1,2,2-tetraphenylethenediyl)scandium(III) toluene hemisolvate, [Sc(C 17 H 13 )(C 26 H 20 )(C 4 H 8 O)]·0.5C 7 H 8 or [(η 5 -1,3-Ph 2 C 5 H 3 )Sc(η 6 -C 2 Ph 4 )(THF)]·0.5(toluene), (5b), poly[[(μ 2 -η 3 :η 3 -anthracenediyl)bis(η 6 -anthracenediyl)bis(η 5 -1,3-diphenylcyclopentadienyl)tetrakis(tetrahydrofuran)dipotassiumdiscandium(III)] tetrahydrofuran monosolvate], {[K 2 Sc 2 (C 14 H 10 ) 3 (C 17 H 13 ) 2 (C 4 H 8 O) 4 ]·C 4 H 8 O} n or [K(THF) 2 ] 2 [(1,3-Ph 2 C 5 H 3 ) 2 Sc 2 (C 14 H 10 ) 3 ]·THF, (6), and 1,4-diphenylcyclopenta-1,3-diene, C 17 H 14 , (3a), have been established. The [Sc(η 6 -C 2 Ph 4 ) 2 ] - complex anion in (1b) contains the tetraphenylethylene dianion in a symmetrical bis-η 3 -allyl coordination mode. The complex homoleptic [Sc(η 6 -C 2 Ph 4 ) 2 ] - anion retains its structure in THF solution, displaying hindered rotation of the coordinated phenyl rings. The 1D 1 H and 13 C{ 1 H}, and 2D COSY 1 H- 1 H and 13 C- 1 H NMR data are presented for M[Sc(Ph 4 C 2 ) 2 ]·xTHF [M = Na and x = 4 for (1a); M = K and x = 3.5 for (2a)] in THF-d 8 media. Complex (5b) exhibits an unsymmetrical bis-η 3 -allyl coordination mode of the dianion, but this changes to a η 4 coordination mode for (1,3-Ph 2 C 5 H 3 )Sc(Ph 4 C 2 )(THF) 2 , (5a), in THF-d 8 solution. A 45 Sc NMR study of (2a) and UV-Vis studies of (1a), (2a) and (5a) indicate a significant covalent contribution to the Sc-Ph 4 C 2 bond character. The unique Sc ate complex, (6), contains three anthracenide dianions demonstrating both a η 6 -coordination mode for two bent ligands and a μ 2 -η 3 :η 3 -bridging mode of a flat ligand. Each [(1,3-Ph 2 C 5 H 3 ) 2 Sc 2 (C 14 H 10 ) 3 ] 2- dianionic unit is connected to four neighbouring units via short contacts with [K(THF) 2 ] + cations, forming a two-dimensional coordination polymer framework parallel to (001).

Synchronized separation, concentration and determination of trace sulfadiazine and sulfamethazine in food and environment by using polyoxyethylene lauryl ether-salt aqueous two-phase system coupled to high-performance liquid chromatography.

PubMed

Lu, Yang; Cong, Biao; Tan, Zhenjiang; Yan, Yongsheng

2016-11-01

Polyoxyethylene lauryl ether (POELE10)-Na2C4H4O6 aqueous two-phase extraction system (ATPES) is a novel and green pretreatment technique to trace samples. ATPES coupled with high-performance liquid chromatography (HPLC) is used to analyze synchronously sulfadiazine (SDZ) and sulfamethazine (SMT) in animal by-products (i.e., egg and milk) and environmental water sample. It was found that the extraction efficiency (E%) and the enrichment factor (F) of SDZ and SMT were influenced by the types of salts, the concentration of salt, the concentration of POELE10 and the temperature. The orthogonal experimental design (OED) was adopted in the multi-factor experiment to determine the optimized conditions. The final optimal condition was as following: the concentration of POELE10 is 0.027gmL(-1), the concentration of Na2C4H4O6 is 0.180gmL(-1) and the temperature is 35°C. This POELE10-Na2C4H4O6 ATPS was applied to separate and enrich SDZ and SMT in real samples (i.e., water, egg and milk) under the optimal conditions, and it was found that the recovery of SDZ and SMT was 96.20-99.52% with RSD of 0.35-3.41%. The limit of detection (LOD) of this method for the SDZ and SMT in spiked samples was 2.52-3.64pgmL(-1), and the limit of quantitation (LOQ) of this method for the SDZ and SMT in spiked samples was 8.41-12.15pgmL(-1). Copyright © 2016 Elsevier Inc. 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.

A combined binding mechanism of nonionic ethoxylated surfactants to bovine serum albumin revealed by fluorescence and circular dichroism.

PubMed

Iovescu, Alina; Băran, Adriana; Stîngă, Gabriela; Cantemir-Leontieş, Anca Ruxandra; Maxim, Monica Elisabeta; Anghel, Dan Florin

2015-12-01

The study systematically investigates aqueous mixtures of fixed bovine serum albumin (BSA) and various ethoxylated nonionic surfactants belonging to a homologous series or not. Mono-disperse tetra-(C12E4), hexa-(C12E6) and octa-ethyleneglycol mono-n-dodecyl ether (C12E8), and poly-disperse eicosa-ethyleneglycol mono-n-tetradecyl ether (C14EO20) are respectively employed. Fluorescence and circular dichroism measurements are performed at surfactant/protein molar ratios (rm)s lower and higher than one. We aim to get new insights into the binding mechanism of these species and to differentiate among the interaction abilities of these surfactants. The relative magnitude of the binding thermodynamic parameters by fluorescence, and the increase of α-helix prove that hydrogen bonding drives the interaction next to the hydrophobic attraction. C12En (n=4,6,8) develop more H bonds with the albumin than C14EO20 owing to a zigzag conformation of their short ethyleneoxide chains. Among the homologous surfactants, C12E6 has a slightly stronger interaction with BSA due to a maximal number of H bonds at a minimal hindering. Static fluorescence and dynamic fluorescence indicate an inter-conversion between the tryptophan (Trp) rotamers which happens around the surfactants critical micellar concentration. For C14EO20, the meander conformation of the polar group determines a less evident conversion of the Trp rotamers and smaller α-helix rise. Binding isotherms of the homologous surfactants and the fluorescence quenching mechanism by C12E6 are also provided. Copyright © 2015 Elsevier B.V. All rights reserved.

Resonance Raman spectroscopy of 2H-labelled spheroidenes in petroleum ether and in the Rhodobacter sphaeroides reaction centre.

PubMed

Kok, P; Köhler, J; Groenen, E J; Gebhard, R; van der Hoef, I; Lugtenburg, J; Farhoosh, R; Frank, H A

1997-03-01

As a step towards the structural analysis of the carotenoid spheroidene in the Rhodobacter sphaeroides reaction centre, we present the resonance Raman spectra of 14-2H, 15-2H, 15'-2H, 14'-2H, 14,15'-2H2 and 15-15'-2H2 spheroidenes in petroleum ether and, except for 14,15'-2H2 spheroidene, in the Rb. sphaeroides R26 reaction center (RC). Analysis of the spectral changes upon isotopic substitution allows a qualitative assignment of most of the vibrational bands to be made. For the all-trans spheroidenes in solution the resonance enhancement of the Raman bands is determined by the participation of carbon carbon stretching modes in the centre of the conjugated chain, the C9 to C15' region. For the RC-bound 15,15'-cis spheroidenes, enhancement is determined by the participation of carbon-carbon stretching modes in the centre of the molecule, the C13 to C13' region. Comparison of the spectra in solution and in the RC reveals evidence for an out-of-plane distortion of the RC-bound spheroidene in the central C14 to C14' region of the carotenoid. The characteristic 1240 cm-1 band in the spectrum of the RC-bound spheroidene has been assigned to a normal mode that contains the coupled C12-C13 and C13'-C12' stretch vibrations.

1,2,3-triazolate-bridged tetradecametallic transition metal clusters [M14(L)6O6(OMe)18X6] (M=FeIII, CrIII and VIII/IV) and related compounds: ground-state spins ranging from S=0 to S=25 and spin-enhanced magnetocaloric effect.

PubMed

Shaw, Rachel; Laye, Rebecca H; Jones, Leigh F; Low, David M; Talbot-Eeckelaers, Caytie; Wei, Qiang; Milios, Constantinos J; Teat, Simon; Helliwell, Madeleine; Raftery, James; Evangelisti, Marco; Affronte, Marco; Collison, David; Brechin, Euan K; McInnes, Eric J L

2007-06-11

We report the synthesis, by solvothermal methods, of the tetradecametallic cluster complexes [M14(L)6O6(OMe)18Cl6] (M=FeIII, CrIII) and [V14(L)6O6(OMe)18Cl6-xOx] (L=anion of 1,2,3-triazole or derivative). Crystal structure data are reported for the {M14} complexes [Fe14(C2H2N3)6O6(OMe)18Cl6], [Cr14(bta)6O6(OMe)18Cl6] (btaH=benzotriazole), [V14O6(Me2bta)6(OMe)18Cl6-xOx] [Me2btaH=5,6-Me2-benzotriazole; eight metal sites are VIII, the remainder are disordered between {VIII-Cl}2+ and {VIV=O}2+] and for the distorted [FeIII14O9(OH)(OMe)8(bta)7(MeOH)5(H2O)Cl8] structure that results from non-solvothermal synthetic methods, highlighting the importance of temperature regime in cluster synthesis. Magnetic studies reveal the {Fe14} complexes to have ground state electronic spins of S

Investigation of Thermochemistry Associated with the Carbon–Carbon Coupling Reactions of Furan and Furfural Using ab Initio Methods

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

Liu, Cong; Assary, Rajeev S.; Curtiss, Larry A.

2014-06-26

Upgrading of furan and small oxygenates obtained from the decomposition of cellulosic materials via formation of carbon-carbon bonds is critical to effective conversion of biomass to liquid transportation fuels. Simulation-driven molecular level understanding of carbon-carbon bond formation is required to design efficient catalysts and processes. Accurate quantum chemical methods are utilized here to predict the reaction energetics for conversion of furan (C4H4O) to C5-C8 ethers and the transformation of furfural (C5H6O2) to C13-C26 alkanes. Furan, can be coupled with various C1 to C4 lower molecular weight carbohydrates obtained from the pyrolysis via Diels-Alder type reactions in the gas phase tomore » produce C5-C8 cyclic ethers. The computed reaction barriers for these reactions (~25 kcal/mol) are lower than the cellulose activation or decomposition reactions (~50 kcal/mol). Cycloaddition of C5-C8 cyclo-ethers with furans can also occur in the gas phase, and the computed activation energy is similar to that of the first Diels-Alder reaction. Furfural, obtained from biomass, can be coupled with aldehydes or ketones with α-hydrogen atoms to form longer chain aldol products and these aldol products can undergo vapor phase hydrocycloaddition (activation barrier of ~20 kcal/mol) to form the precursors of C26 cyclic hydrocarbons. These thermochemical studies provide the basis for further vapor phase catalytic studies required for upgrading of furans/furfurals to longer chain hydrocarbons.« less

Synthesis, crystal structure and thermal study of the hybrid nickel sulfate: C6N2H16[Ni(H2O)6(SO4)2].2H2O

NASA Astrophysics Data System (ADS)

Ngopoh, F. A. I.; Hamdi, N.; Chaouch, S.; Lachkar, M.; da Silva, I.; El Bali, B.

2018-03-01

A new inorganic-organic hybrid open framework nickel sulfate C6N2H16[Ni(H2O)6(SO4)2].2H2O has been synthesized by slow evaporation in aqueous solution using trans-1,4-diaminocyclohexane as structure-directing agent. It was characterized by single-crystal X-ray diffraction, infrared spectroscopy and analyzed by TGA-DSC. The compound crystallizes in the monoclinic space group P21/n, with the unit cell parameters of a = 6.2586 Å, b = 12.3009 Å, c = 13.2451 Å, β = 98,047°, Z = 4. Its crystal structure consists of isolated polyhedrons [Ni(H2O)6]2+ and [SO4]2- and free water which connects through hydrogen bonds. This association results in the porous framework where the protonated organic molecule trans-1,4-diaminocyclohexane is located as a counter ion. The IR spectra Shows the bands corresponding to the sulfate anion, water molecule and diprotonated trans-1-4-diaminocyclohexane. Thermal study indicates the loss of water molecules and the degradation of trans-1-4-diaminocyclohexane.

Crystal structures of a novel NNN pincer ligand and its dinuclear titanium(IV) alkoxide pincer complex.

PubMed

Pedziwiatr, Jakub; Ghiviriga, Ion; Abboud, Khalil A; Veige, Adam S

2017-02-01

This report describes a synthetic protocols and the crystal structures involving a novel pincer-type H 3 [NNN] ligand, namely di-μ-bromido-μ-{2-(2,2-di-methylpropanimido-yl)- N -[2-(2,2-di-methyl-propanimido-yl)-4-methyl-phen-yl]-4-methylaniline}-bis-[(diethyl ether)lithium], [Li 2 Br 2 (C 24 H 33 N 3 )(C 4 H 10 O) 2 ] ( 1 ) and a dinuclear metal complex, namely di-μ-bromido-2:3κ 4 Br : Br -bis-{2-(2,2-di-methylpropanimido-yl)- N -[2-(2,2-di-methyl-propanimido-yl)-4-methyl-phen-yl]-4-methylaniline}-1κ 3 N , N ', N '';4κ 3 N , N ', N ''-tetra-μ-iso-propano-lato-1:2κ 4 O : O ;3:4κ 4 O : O -diiso-propano-lato-1κ O ,4κ O -2,3-dilithium-1,4-dititanium, [Li 2 Ti 2 Br 2 (C 24 H 32 N 3 ) 2 (C 3 H 7 O) 6 ] or {[NHNNH]Ti(O i Pr) 3 (LiBr) 2 } 2 ( 2 ). Complex 1 , which sits on a twofold rotation axis, is a rare example of a pincer-type ligand which bears ketimine side arms. A unique feature of complex 1 is that the ketimine N atoms have an LiBr(Et 2 O) fragment bonded to them, with the Li atom adopting a distorted tetra-hedral geometry. This particular fragment creates an LiBr bridge between the two ketimine sidearms, which leads to a cage-type appearance of the ligand. Complex 2 consists of the previously described ligand and a Ti IV metal atom in an octa-hedral environment, and is located on an inversion center. Complex 2 crystallizes as a dinuclear species with the metal atoms being bridged by an LiBr entity [the Br atoms are disordered and refined in two positions with their site occupation factors refining to 0.674 (12)/0.372 (12)], and the Li cation being bonded to the isopropoxide O atoms (Li having a tetra-hedral coordination as in 1 ). The organic ligand of compound 2 exhibits disorder in its periphery groups; isopropyl and tert -butyl groups (occupation factors fixed at 0.6/0.4). The novel [NNN]H 3 pincer-type ligand was characterized by multinuclear and multidimensional NMR, HRMS and X-ray crystallography. The dinuclear metal complex 2 was characterized by X-ray crystallography. Although each structure exhibits donor N-H groups, no hydrogen bonding is found in either one, perhaps due to the bulky groups around them. One of the ethyl groups of the ether ligand of 1 is disordered and refined in two parts with site-occupation factors of 0.812 (8) and 0.188 (8). One and a half toluene solvent mol-ecules are also present in the asymmetric unit of 2 . The toluene mol-ecules were significantly disordered and could not be modeled properly, thus SQUEEZE [Spek (2015 ▸). Acta Cryst. C 71 , 9-18] was used to remove their contributions to the overall intensity data.

Solvent-assisted stir bar sorptive extraction by using swollen polydimethylsiloxane for enhanced recovery of polar solutes in aqueous samples: Application to aroma compounds in beer and pesticides in wine.

PubMed

Ochiai, Nobuo; Sasamoto, Kikuo; David, Frank; Sandra, Pat

2016-07-15

A novel solvent-assisted stir bar sorptive extraction (SA-SBSE) technique was developed for enhanced recovery of polar solutes in aqueous samples. A conventional PDMS stir bar was swollen in several solvents with log Kow ranging from 1.0 to 3.5 while stirring for 30min prior to extraction. After extraction, thermal desorption - gas chromatography - (tandem) mass spectrometry (TD-GC-(MS/)MS) or liquid desorption - large volume injection (LD-LVI)-GC-MS were performed. An initial study involved investigation of potential solvents for SA-SBSE by weighing of the residual solvent in the swollen PDMS stir bar before and after extraction. Compared to conventional SBSE, SA-SBSE using diethyl ether, methyl isobutyl ketone, dichloromethane, diisopropyl ether and toluene provided higher recoveries from water samples for test solutes with log Kow<2.5. For SA-SBSE using dichloromethane, recoveries were improved by factors of 1.4-4.1, while maintaining or even improving the recoveries for test solutes with log Kow>2.5. The performance of the SA-SBSE method using dichloromethane, diisopropyl ether, and cyclohexane is illustrated with analyses of aroma compounds in beer and of pesticides in wine. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Phosphoglucoisomerase-catalyzed interconversion of hexose phosphates: isotopic discrimination between hydrogen and deuterium.

PubMed

Malaisse, W J; Malaisse-Lagae, F; Liemans, V; Ottinger, R; Willem, R

1990-03-27

The discrimination between the isotopes of hydrogen in the reaction catalyzed by yeast phosphoglucoisomerase is examined by NMR, as well as by spectrofluorometric or radioisotopic methods. The monodirectional conversion of D-glucose 6-phosphate to D-fructose 6-phosphate displays a lower maximal velocity with D-[2-2H]glucose 6-phosphate than unlabelled D-glucose 6-phosphate, with little difference in the affinity of the enzyme for these two substrates. About 72% of the deuterium located on the C2 of D-[1-13C,2-2H]glucose 6-phosphate is transferred intramolecularly to the C1 of D-[1-13C,1-2H]fructose 6-phosphate. The velocity of the monodirectional conversion of D-[U-14C]glucose 6-phosphate (or D-[2-3H]glucose 6-phosphate) to D-fructose 6-phosphate is virtually identical in H2O and D2O, respectively, but is four times lower with the tritiated than 14C-labelled ester. In the monodirectional reaction, the intramolecular transfer from the C2 of D-[2-3H]glucose 6-phosphate is higher in the presence of D2O than H2O. Whereas prolonged exposure of D-[1-13C]glucose 6-phosphate to D2O, in the presence of phosphoglucoisomerase, leads to the formation of both D-[1-13C,2-2H]glucose 6-phosphate and D-[1-13C,1-2H]fructose 6-phosphate, no sizeable incorporation of dueterium from D2O on the C1 of D-[1-13C]fructose 1,6-bisphosphate is observed when the monodirectional conversion of D-[1-13C]glucose 6-phosphate occurs in the concomitant presence of phosphoglucoisomerase and phosphofructokinase. The latter finding contrasts with the incorporation of hydrogen from 1H2O or tritium from 3H2O in the monodirectional conversion of D-[2-3H]glucose 6-phosphate and unlabelled D-glucose 6-phosphate, respectively, to their corresponding ketohexose esters.

Pincer phosphine complexes of ruthenium: formation of Ru(P-O-P)(PPh3)HCl (P-O-P = xantphos, DPEphos, (Ph2PCH2CH2)2O) and Ru(dppf)(PPh3)HCl and characterization of cationic dioxygen, dihydrogen, dinitrogen, and arene coordinated phosphine products.

PubMed

Ledger, Araminta E W; Moreno, Aitor; Ellul, Charles E; Mahon, Mary F; Pregosin, Paul S; Whittlesey, Michael K; Williams, Jonathan M J

2010-08-16

Treatment of Ru(PPh(3))(3)HCl with the pincer phosphines 9,9-dimethyl-4,5-bis(diphenylphosphino)xanthene (xantphos), bis(2-diphenylphosphinophenyl)ether (DPEphos), or (Ph(2)PCH(2)CH(2))(2)O affords Ru(P-O-P)(PPh(3))HCl (xantphos, 1a; DPEphos, 1b; (Ph(2)PCH(2)CH(2))(2)O, 1c). The X-ray crystal structures of 1a-c show that all three P-O-P ligands coordinate in a tridentate manner through phosphorus and oxygen. Abstraction of the chloride ligand from 1a-c by NaBAr(4)(F) (BAr(4)(F) = B(3,5-C(6)H(3)(CF(3))(2))(4)) gives the cationic aqua complexes [Ru(P-O-P)(PPh(3))(H(2)O)H]BAr(4)(F) (3a-c). Removal of chloride from 1a by AgOTf yields Ru(xantphos)(PPh(3))H(OTf) (2a), which reacts with water to form [Ru(xantphos)(PPh(3))(H(2)O)H](OTf). The aqua complexes 3a-b react with O(2) to generate [Ru(xantphos)(PPh(3))(eta(2)-O(2))H]BAr(4)(F) (5a) and [Ru(DPEphos)(PPh(3))(eta(2)-O(2))H]BAr(4)(F) (5b). Addition of H(2) or N(2) to 3a-c yields the thermally unstable dihydrogen and dinitrogen species [Ru(P-O-P)(PPh(3))(eta(2)-H(2))H]BAr(4)(F) (6a-c) and [Ru(P-O-P)(PPh(3))(N(2))H]BAr(4)(F) (7a-c), which have been characterized by multinuclear NMR spectroscopy at low temperature. Ru(PPh(3))(3)HCl reacts with 1,1'-bis(diphenylphosphino)ferrocene (dppf) to give the 16-electron complex Ru(dppf)(PPh(3))HCl (1d), which upon treatment with NaBAr(4)(F), affords [Ru(dppf){(eta(6)-C(6)H(5))PPh(2)}H]BAr(4)(F) (8), in which the PPh(3) ligand binds eta(6) through one of the PPh(3) phenyl rings. Reaction of 8 with CO or PMe(3) at elevated temperatures yields the 18-electron products [Ru(dppf)(PPh(3))(CO)(2)H]BAr(F)(4) (9) and [Ru(PMe(3))(5)H]BAr(4)(F) (10).

AtomicNuclearProperties

Science.gov Websites

) Polytrifluorochloroethylene [C2F3Cl]n Polyvinylacetate [CH2CHOCOCH3]n Polyvinyl alcohol (C2H3-O-H)n Polyvinyl butyral [C8H1302 other materal for properties of interest in high-energy physics: stopping power (<-dE/dx>) tables (C10H16O) Aniline (C6H5NH2) Anthracene (C14H10) Benzene C6H6 Butane (C4H10) n-Butyl alcohol (C4H9OH) Carbon

rac-(S,S)-Bis(1-ferrocenylbut-3-en-yl) ether.

PubMed

Xie, Hao-Jun; Zhao, Chun-Zheng; Sun, Jun; Chen, Si; Wang, Jian-Jun

2013-01-01

The title complex, [Fe2(C5H5)2(C18H20O)], formed by dehydration of 1-ferrocenylbut-3-en-1-ol, crystallizes as a racemic compound. The central C-O-C fragment, in which the C atoms are the chiral centers, is characterized by an angle of 116.26 (10)° at the O atom. One ferrocene group shows a staggered conformation whereas the other shows an eclipsed conformation.

Synthesis of carbon-11-labeled 5-HT6R antagonists as new candidate PET radioligands for imaging of Alzheimer's disease.

PubMed

Wang, Xiaohong; Dong, Fugui; Miao, Caihong; Li, Wei; Wang, Min; Gao, Mingzhang; Zheng, Qi-Huang; Xu, Zhidong

2018-06-01

Carbon-11-labeled serotonin (5-hydroxytryptamine) 6 receptor (5-HT 6 R) antagonists, 1-[(2-bromophenyl)sulfonyl]-5-[ 11 C]methoxy-3-[(4-methyl-1-piperazinyl)methyl]-1H-indole (O-[ 11 C]2a) and 1-[(2-bromophenyl)sulfonyl]-5-methoxy-3-[(4-[ 11 C]methyl-1-piperazinyl)methyl]-1H-indole (N-[ 11 C]2a), 5-[ 11 C]methoxy-3-((4-methylpiperazin-1-yl)methyl)-1-(phenylsulfonyl)-1H-indole (O-[ 11 C]2b) and 5-methoxy-3-((4-[ 11 C]methylpiperazin-1-yl)methyl)-1-(phenylsulfonyl)-1H-indole (N-[ 11 C]2b), 1-((4-isopropylphenyl)sulfonyl)-5-[ 11 C]methoxy-3-((4-methylpiperazin-1-yl)methyl)-1H-indole (O-[ 11 C]2c) and 1-((4-isopropylphenyl)sulfonyl)-5-methoxy-3-((4-[ 11 C]methylpiperazin-1-yl)methyl)-1H-indole (N-[ 11 C]2c), 1-((4-fluorophenyl)sulfonyl)-5-[ 11 C]methoxy-3-((4-methylpiperazin-1-yl)methyl)-1H-indole (O-[ 11 C]2d) and 1-((4-fluorophenyl)sulfonyl)-5-methoxy-3-((4-[ 11 C]methylpiperazin-1-yl)methyl)-1H-indole (N-[ 11 C]2d), were prepared from their O- or N-desmethylated precursors with [ 11 C]CH 3 OTf through O- or N-[ 11 C]methylation and isolated by HPLC combined with SPE in 40-50% radiochemical yield, based on [ 11 C]CO 2 and decay corrected to end of bombardment (EOB). The radiochemical purity was >99%, and the molar activity (MA) at EOB was 370-740 GBq/μmol with a total synthesis time of ∼40-min from EOB. Copyright © 2018 Elsevier Ltd. All rights reserved.

(C6N2H16)[Co(H2O)6](SO4)2.2H2O: A new hybrid material based on sulfate templated by diprotonated trans-1,4-diaminocyclohexane

NASA Astrophysics Data System (ADS)

Hamdi, N.; Ngopoh, F. A. I.; da Silva, I.; El Bali, B.; Lachkar, M.

2018-03-01

Employing trans-1,4-diaminocyclohexane (DACH) as template, the new hybrid sulphate (C6N2H16)[Co(H2O)6](SO4)2.2H2O was prepared in solution. Single-crystal X-ray diffraction analysis shows that it crystallizes in the monoclinic system (S.G.: P 21/n), with the following unit-cell parameters (Å,°): a = 6.2897(2), b = 12.3716(6), c = 13.1996(4), β = 98.091(3) V = 1016.89(7) Å3, Z = 4. Its 3D crystal structure is made upon isolated [Co(H2O)6] octahedra, regular [SO4] tetrahedra, protonated DACH and free H2O molecules, which interact through N-H···O and O-H···O hydrogen bonds. The Fourier transform infrared result exhibits bands corresponding to the vibrations of DACH, sulfate group and water molecules. The thermal decomposition of the phase consists mainly in the loss of the organic moiety and one sulfate group, leading thus to the formation of anhydrous cobalt sulfate.

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.

Synaptic Mechanisms of Action of Convulsion-Producing Anticholinesterases. Characterization of Di-Isopropyl Phosphorofluoridate-Induced Epileptiform Activity in the Mammalian Hippocampus.

DTIC Science & Technology

1983-10-01

O ) OV6 ISOBSLET *SECURITY CLASSIFICATION OF THIS PAGE (Oc~ Dt. Entered) - 4 .. I,3...* %%S& P 4. A I IUN U ,13 ’ A ^II t~,.. I. f ltnew- A "viously...Abstr. 8:558, 1982. 73. Gustafsson, B., Galvan, M., Grafe, P . and Wigstrom, H. A transient outward current in a mammalian central neurone blocked by 4...TEST CHART N4ATIONAL BUREAU CF STANAROS -963 - A ............ ............ AD _ _ _ Report No. 1 SYNAPTIC MECHANISMS OF ACTION OF CONVULSION-PRODUCING

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

Synthesis and biological evaluation of arctigenin ester and ether derivatives as activators of AMPK.

PubMed

Shen, Sida; Zhuang, Jingjing; Chen, Yijia; Lei, Min; Chen, Jing; Shen, Xu; Hu, Lihong

2013-07-01

A series of new arctigenin and 9-deoxy-arctigenin derivatives bearing different ester and ether side chains at the phenolic hydroxyl positions are designed, synthesized, and evaluated for activating AMPK potency in L6 myoblasts. Initial biological evaluation indicates that some alkyl ester and phenethyl ether arctigenin derivatives display potential activities in AMPK phosphorylation improvement. Further structure-activity relationship analysis shows that arctigenin ester derivatives 3a, 3h and 9-deoxy-arctigenin phenethyl ether derivatives 6a, 6c, 6d activate AMPK more potently than arctigenin. Moreover, the 2-(3,4-dimethoxyphenyl)ethyl ether moiety of 6c has been demonstrated as a potential functional group to improve the effect of AMPK phosphorylation. The structural optimization of arctigenin leads to the identification of 6c as a promising lead compound that exhibits excellent activity in AMPK activation. Copyright © 2013 The Authors. Published by Elsevier Ltd.. All rights reserved.

A Mechanistical Study on the Formation of Dimethyl Ether (CH3OCH3) and Ethanol (CH3CH2OH) in Methanol-containing Ices and Implications for the Chemistry of Star-forming Regions

NASA Astrophysics Data System (ADS)

Bergantini, Alexandre; Góbi, Sándor; Abplanalp, Matthew J.; Kaiser, Ralf I.

2018-01-01

The underlying formation mechanisms of complex organic molecules (COMs)—in particular, structural isomers—in the interstellar medium (ISM) are largely elusive. Here, we report new experimental findings on the role of methanol (CH3OH) and methane (CH4) ices in the synthesis of two C2H6O isomers upon interaction with ionizing radiation: ethanol (CH3CH2OH) and dimethyl ether (CH3OCH3). The present study reproduces the interstellar abundance ratios of both species with ethanol to dimethyl ether branching ratios of (2.33 ± 0.14):1 suggesting that methanol and methane represents the key precursor to both isomers within interstellar ices. Exploiting isotopic labeling combined with reflectron time-of-flight mass spectrometry (Re-TOF-MS) after isomer selective vacuum ultra-violet (VUV) photoionization of the neutral molecules, we also determine the formation mechanisms of both isomers via radical–radical recombination versus carbene (CH2) insertion with the former pathway being predominant. Formation routes to higher molecular weight reaction products such as ethylene glycol (HOCH2CH2OH), dimethyl peroxide (CH3OOCH3), and methoxymethanol (CH3OCH2OH) are discussed briefly as well.

Selective borane reduction of phosphinoferrocene carbaldehydes to phosphinoalcohol-borane adducts. The coordination behaviour of 1-(diphenylphosphino)-1'-(methoxymethyl)ferrocene, a new ferrocene O,P-hybrid donor prepared from such an adduct.

PubMed

Stěpnička, Petr; Císařová, Ivana

2013-03-14

The reduction of ferrocene phosphino-aldehydes, R(2)PfcCHO (R = Ph, 2; Cy, 3; fc = ferrocene-1,1'-diyl, Cy = cyclohexyl) and (S(p))-[Fe(η(5)-C(5)H(3)-1-CHO-2-PPh(2))(η(5)-C(5)H(5))] ((S(p))-4), with BH(3)·THF or BH(3)·SMe(2) in THF at 0 °C selectively afforded the corresponding phosphinoalcohol-borane adducts, R(2)PfcCH(2)OH·BH(3) (R = Ph, 5; Cy, 6) and (S(p))-[Fe(η(5)-C(5)H(3)-1-CH(2)OH-2-PPh(2))(η(5)-C(5)H(5))]·BH(3) ((S(p))-7), in quantitative yields. In contrast, the reactions performed at elevated temperatures favoured the formation of methyl derivatives (e.g., Ph(2)PfcCH(3)·BH(3) (8)) resulting from overreduction (deoxygenation). The crystal structures of 3, 5, (S(p))-7, 8 and Cy(2)PfcBr (9) have been determined by single-crystal X-ray diffraction analysis. The crystal assemblies of adducts 5 and (S(p))-7 are built up by means of C-H...O contacts, O-H...HB dihydrogen bonds and other soft interactions but, surprisingly, not via the conventional O-H...O hydrogen bonds. Adduct 5 was smoothly deprotected to give the corresponding free phosphine, Ph(2)PfcCH(2)OH (1), and was further used for the preparation of a hybrid phosphinoether ligand, Ph(2)PfcCH(2)OMe (11). The latter compound was studied as a donor for Group 8-10 metal ions and for Cu(i), whereupon the following complexes were isolated and structurally characterised: [(η(6)-p-cymene)RuCl(2)(11-κP)] (12*), [(η(6)-p-cymene)RuCl(11-κP)(MeCN)][SbF(6)] (13*), [RhCl(cod)(11-κP)] (cod = η(2):η(2)-cycloocta-1,5-diene; 14), trans-[PdCl(2)(11-κP)(2)] (trans-15*), [PdCl(μ-Cl)(11-κP)](2) (16*), cis- and trans-[PtCl(2)(11-κP)(2)] (cis-17 and trans-17*), and [Cu(CF(3)SO(3)-κO)(11-κP)(H(2)O)] (18) (the asterisk indicates that the crystal structure was determined). In all these compounds, ligand 11 behaves as a P-monodentate donor while its ether group remains uncoordinated. This probably reflects structural flexibility of 11 resulting from the presence of the methylene linker and also distinguishes 11 from its known, non-spaced analogue Ph(2)PfcOMe.

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

CF3+ fragmentation by electron impact ionization of perfluoro-propyl-vinyl-ethers, C5F10O, in gas phase

NASA Astrophysics Data System (ADS)

Kondo, Yusuke; Ishikawa, Kenji; Hayashi, Toshio; Miyawaki, Yudai; Takeda, Keigo; Kondo, Hiroki; Sekine, Makoto; Hori, Masaru

2015-04-01

The gas phase fragmentations of perfluoro-propyl-vinyl ether (PPVE, C5F10O) are studied experimentally. Dominant fragmentations of PPVE are found to be the result of a dissociative ionization reaction, i.e., CF3+ via direct bond cleavage, and C2F3O- and C3F7O- via electron attachment. Regardless of the appearance energy of around 14.5 eV for the dissociative ionization of CF3+, the observed ion efficiency for the CF3+ ion was extremely large the order of 10-20 cm-2, compared with only 10-21 cm-2 for the other channels. PPVE characteristically generated CF3+ as the largest abundant ion are advantageous for use of feedstock gases in plasma etching processes.

A novel fibrinolytic enzyme (nattokinase) in the vegetable cheese Natto; a typical and popular soybean food in the Japanese diet.

PubMed

Sumi, H; Hamada, H; Tsushima, H; Mihara, H; Muraki, H

1987-10-15

A strong fibrinolytic activity was demonstrated in the vegetable cheese Natto, which is a typical soybean food eaten in Japan. The average activity was calculated at about 40 CU (plasmin units)/g wet weight. This novel fibrinolytic enzyme, named nattokinase, was easily extracted with saline. The mol. wt and pI were about 20,000 and 8.6, respectively. Nattokinase not only digested fibrin but also the plasmin substrate H-D-Val-Leu-Lys-pNA (S-2251), which was more sensitive to the enzyme than other substrates tried. Diisopropyl fluorophosphate and 2,2,2-trichloro-1-hydroxyethyl-o,o-dimethylphosphate strongly inhibited this fibrinolytic enzyme.

Interstellar Alcohols

NASA Technical Reports Server (NTRS)

Charnley, S. B.; Kress, M. E.; Tielens, A. G. G. M.; Millar, T. J.

1995-01-01

We have investigated the gas-phase chemistry in dense cores where ice mantles containing ethanol and other alcohols have been evaporated. Model calculations show that methanol, ethanol, propanol, and butanol drive a chemistry leading to the formation of several large ethers and esters. Of these molecules, methyl ethyl ether (CH3OC2H5) and diethyl ether (C2H5)2O attain the highest abundances and should be present in detectable quantities within cores rich in ethanol and methanol. Gas-phase reactions act to destroy evaporated ethanol and a low observed abundance of gas-phase C,H,OH does not rule out a high solid-phase abundance. Grain surface formation mechanisms and other possible gas-phase reactions driven by alcohols are discussed, as are observing strategies for the detection of these large interstellar molecules.

Anhydrous versus hydrated N4-substituted 1H-pyrazolo[3,4-d]pyrimidine-4,6-diamines: hydrogen bonding in two and three dimensions.

PubMed

Trilleras, Jorge; Quiroga, Jairo; Cobo, Justo; Marchal, Antonio; Nogueras, Manuel; Low, John N; Glidewell, Christopher

2008-10-01

Ten new N(4)-substituted 1H-pyrazolo[3,4-d]pyrimidine-4,6-diamines have been synthesized and the structures of nine of them are reported here, falling into two clear groups, those which are stoichiometric hydrates and those which crystallize in solvent-free forms. In each of N(4)-methyl-N(4)-phenyl-1H-pyrazolo[3,4-d]pyrimidine-4,6-diamine, C(12)H(12)N(6) (I), N(4)-cyclohexyl-N(4)-methyl-1H-pyrazolo[3,4-d]pyrimidine-4,6-diamine, C(12)H(18)N(6) (II), and N(4)-(3-chlorophenyl)-1H-pyrazolo[3,4-d]pyrimidine-4,6-diamine, C(11)H(9)ClN(6) (III), the molecules are linked into hydrogen-bonded sheets. The molecules of 2-{4-(6-amino-1H-pyrazolo[3,4-d]pyrimidin-4-yl)piperazin-1-yl}ethanol, C(11)H(17)N(7)O (IV), are linked into a three-dimensional framework, while the structure of N(4)-methyl-N(4)-(4-methylphenyl)-1H-pyrazolo[3,4-d]pyrimidine-4,6-diamine monohydrate, C(13)H(14)N(6) x H(2)O (V), is only two-dimensional despite the presence of five independent hydrogen bonds. The stoichiometric hemihydrates N(4)-ethyl-N(4)-phenyl-1H-pyrazolo[3,4-d]pyrimidine-4,6-diamine hemihydrate, C(13)H(14)N(6) x 0.5 H(2)O (VI) and N(4)-(4-methoxyphenyl)-N(4)-methyl-1H-pyrazolo[3,4-d]pyrimidine-4,6-diamine hemihydrate, C(13)H(14)N(6)O x 0.5 H(2)O (VII), exhibit remarkably similar sheet structures, despite different space groups and Z' values, Z' = 0.5 in C2/c for (VI) and Z' = 1 in P1 for (VII). N(4)-4-Benzyl-N(4)-phenyl-1H-pyrazolo[3,4-d]pyrimidine-4,6-diamine monohydrate, C(18)H(16)N(6) x H(2)O (VIII), crystallizes with Z' = 2 in P2(1)/n, and the four independent molecular components are linked into sheets by a total of 11 intermolecular hydrogen bonds. The sheet structure in {4-(pyrrolidin-1-yl)-1H-pyrazolo[3,4-d]pyrimidine-6-amine} ethanol hemisolvate hemihydrate, C(9)H(12)N(6).0.5C(2)H(6)O x 0.5 H(2)O (IX), is built from the pyrimidine and water components only; it contains eight independent hydrogen bonds, and it very closely mimics the sheets in (VI) and (VII); the ethanol molecules are pendent from these sheets. The N(4)-alkyl-N(4)-aryl-4-aminopyrazolopyrimidine molecules in (I), (V)-(VIII) all adopt very similar conformations, dominated in each case by an intramolecular C-H...pi(arene) hydrogen bond: this interaction is absent from (III) where the molecular conformation is entirely different and probably dominated by the intermolecular hydrogen bonds.

Crystal Structures and Thermal Properties of Two Transition-Metal Compounds {[Ni(DNI)2(H2O)3][Ni(DNI)2 (H2O)4]}·6H2O and Pb(DNI)2(H2O)4 (DNI = 2,4-Dinitroimidazolate)

PubMed Central

Zhang, Guo-Fang; Cai, Mei-Yu; Jing, Ping; He, Chong; Li, Ping; Zhao, Feng-Qi; Li, Ji-Zhen; Fan, Xue-Zhong; Ng, Seik Weng

2010-01-01

Two transition-metal compounds derived from 2,4-dinitroimidazole, {[Ni(DNI)2(H2O)3][Ni(DNI)2 (H2O)4]}·6H2O, 1, and Pb(DNI)2(H2O)4, 2, were characterized by elemental analysis, FT-IR, TG-DSC and X-ray single-crystal diffraction analysis. Crystal data for 1: monoclinic, space group C2/c, a = 26.826(3), b = 7.7199(10), c = 18.579(2) Å, β = 111.241(2)° and Z = 4; 2: monoclinic, space group C2/c, a = 6.5347(6), b = 17.1727(17), c = 14.1011(14) Å, β = 97.7248(10) and Z = 4. Compound 1 contains two isolated nickel centers in its structure, one being six-coordinate and another five-coordinate. The structure of 2 contains a lead (II) center surrounded by two chelating DNI ligands and four water molecules in distorted square-antiprism geometry. The abundant hydrogen bonds in two compounds link the molecules into three-dimensional network and stabilize the molecules. The TG-DSC analysis reveals that the first step is the loss of water molecules and the final residue is the corresponding metal oxides and carbon. PMID:20526419

Infrared matrix-isolation and theoretical studies of the reactions of ferrocene with ozone.

PubMed

Kugel, Roger W; Pinelo, Laura F; Ault, Bruce S

2015-03-19

The reactions between ferrocene (Cp2Fe) (2a) and ozone (O3) were studied using low-temperature matrix-isolation techniques coupled with theoretical density functional theory (DFT) calculations. Co-deposition of Ar/Cp2Fe and Ar/O3 gas mixtures onto a cryogenically cooled CsI window produced a dark-green charge-transfer complex, Cp2Fe-O3, that photodecomposed upon red (λ ≥ 600 nm) and infrared (λ ≥ 1000 nm) irradiation but was stable to green or blue irradiation. Products of photodecomposition were characterized by FT-IR, oxygen-18 labeling, and DFT calculations using the B3LYP functionals and the 6-311G++(d,2p) basis set. Likely, photochemical products included four structures having the molecular formula C10H10FeO, identified by DFT calculations based on their calculated infrared spectra and (18)O isotope shifts. Each of these calculated molecules had one intact and fully coordinated η(5)-C5H5 cyclopentadienyl (Cp) ring and (1) an η(5)-C5H5O cyclic ether (pyran ring) (2b), (2) an η(4)-C5H5O linear aldehyde (2c), (3) a bidentate cyclic aldehyde with a seven-membered ring including the iron atom (2d), or (4) an Fe-O bond and an η(2)-C5H5 (Cp) ring (2e). No conclusive evidence for a gas-phase thermal reaction between ferrocene and ozone was observed under the conditions of these experiments. However, strong evidence for a surface-catalyzed thermal reaction was observed in merged-jet experiments wherein the gases were premixed before deposition. Surface-catalyzed ferrocene-ozone reaction products included a thin film of Fe2O3 observed on the walls of the merged tube as well as cyclopentadiene (C5H6), cyclopentadienone (C5H4O), and further oxidation products observed in the matrix. Possible mechanisms for both the photochemical and the thermal reactions are discussed.

Iron(II) catalysis in oxidation of hydrocarbons with ozone in acetonitrile

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

Bataineh, Hajem; Pestovsky, Oleg; Bakac, Andreja

Oxidation of alcohols, ethers, and sulfoxides by ozone in acetonitrile is catalyzed by submillimolar concentrations of Fe(CH 3CN) 6 2+. The catalyst provides both rate acceleration and greater selectivity toward the less oxidized products. For example, Fe(CH 3CN) 6 2+-catalyzed oxidation of benzyl alcohol yields benzaldehyde almost exclusively (>95%), whereas the uncatalyzed reaction generates a 1:1 mixture of benzaldehyde and benzoic acid. Similarly, aliphatic alcohols are oxidized to aldehydes/ketones, cyclobutanol to cyclobutanone, and diethyl ether to a 1:1 mixture of ethanol and acetaldehyde. The kinetics of oxidation of alcohols and diethyl ether are first-order in [Fe(CH 3CN) 6 2+] andmore » [O 3] and independent of [substrate] at concentrations greater than ~5 mM. In this regime, the rate constant for all of the alcohols is approximately the same, k cat = (8 ± 1) × 10 4 M –1 s –1, and that for (C 2H 5) 2O is (5 ± 0.5) × 10 4 M –1 s –1. In the absence of substrate, Fe(CH 3CN) 6 2+ reacts with O 3 with k Fe = (9.3 ± 0.3) × 10 4 M –1 s –1. The similarity between the rate constants k Fe and k cat strongly argues for Fe(CH 3CN) 6 2+/O 3 reaction as rate-determining in catalytic oxidation. The active oxidant produced in Fe(CH 3CN) 6 2+/O 3 reaction is suggested to be an Fe(IV) species in analogy with a related intermediate in aqueous solutions. As a result, this assignment is supported by the similarity in kinetic isotope effects and relative reactivities of the two species toward substrates.« less

Iron(II) catalysis in oxidation of hydrocarbons with ozone in acetonitrile

DOE PAGES

Bataineh, Hajem; Pestovsky, Oleg; Bakac, Andreja

2015-02-11

Oxidation of alcohols, ethers, and sulfoxides by ozone in acetonitrile is catalyzed by submillimolar concentrations of Fe(CH 3CN) 6 2+. The catalyst provides both rate acceleration and greater selectivity toward the less oxidized products. For example, Fe(CH 3CN) 6 2+-catalyzed oxidation of benzyl alcohol yields benzaldehyde almost exclusively (>95%), whereas the uncatalyzed reaction generates a 1:1 mixture of benzaldehyde and benzoic acid. Similarly, aliphatic alcohols are oxidized to aldehydes/ketones, cyclobutanol to cyclobutanone, and diethyl ether to a 1:1 mixture of ethanol and acetaldehyde. The kinetics of oxidation of alcohols and diethyl ether are first-order in [Fe(CH 3CN) 6 2+] andmore » [O 3] and independent of [substrate] at concentrations greater than ~5 mM. In this regime, the rate constant for all of the alcohols is approximately the same, k cat = (8 ± 1) × 10 4 M –1 s –1, and that for (C 2H 5) 2O is (5 ± 0.5) × 10 4 M –1 s –1. In the absence of substrate, Fe(CH 3CN) 6 2+ reacts with O 3 with k Fe = (9.3 ± 0.3) × 10 4 M –1 s –1. The similarity between the rate constants k Fe and k cat strongly argues for Fe(CH 3CN) 6 2+/O 3 reaction as rate-determining in catalytic oxidation. The active oxidant produced in Fe(CH 3CN) 6 2+/O 3 reaction is suggested to be an Fe(IV) species in analogy with a related intermediate in aqueous solutions. As a result, this assignment is supported by the similarity in kinetic isotope effects and relative reactivities of the two species toward substrates.« less

Preparation of Radiochemical-Labeled Compounds for the U.S. Army Drug Development Program

DTIC Science & Technology

1992-04-20

hydrochloric acid , b) extraction with ether, c) basification with potassium carbonate, d extraction with ether. 2. The crude product was isolated by...Chloride Fisher A-575 880667 Nethylene Chloride Fisher D-37 913251 Alumina, basic Act.I Woelm B 1385 Ethylene Natheson 08227 Hydrochloric Acid Fisher A...4-14C]WR-242511) and [!6- 14C]ertelinic acid were coupleted. A total of 31 m~i of (414 ]WR-238605 was prepared with specific activity of 21 mCi

Expansion of antimonato polyoxovanadates with transition metal complexes: (Co(N3C5H15)2)2[{Co(N3C5H15)2}V15Sb6O42(H2O)]·5H2O and (Ni(N3C5H15)2)2[{Ni(N3C5H15)2}V15Sb6O42(H2O)]·8H2O.

PubMed

Antonova, Elena; Näther, Christian; Kögerler, Paul; Bensch, Wolfgang

2012-02-20

Two new polyoxovanadates (Co(N(3)C(5)H(15))(2))(2)[{Co(N(3)C(5)H(15))(2)}V(15)Sb(6)O(42)(H(2)O)]·5H(2)O (1) and (Ni(N(3)C(5)H(15))(2))(2)[{Ni(N(3)C(5)H(15))(2)}V(15)Sb(6)O(42)(H(2)O)]·8H(2)O (2) (N(3)C(5)H(15) = N-(2-aminoethyl)-1,3-propanediamine) were synthesized under solvothermal conditions and structurally characterized. In both structures the [V(15)Sb(6)O(42)(H(2)O)](6-) shell displays the main structural motif, which is strongly related to the {V(18)O(42)} archetype cluster. Both compounds crystallize in the triclinic space group P1 with a = 14.3438(4), b = 16.6471(6), c = 18.9186(6) Å, α = 87.291(3)°, β = 83.340(3)°, γ = 78.890(3)°, and V = 4401.4(2) Å(3) (1) and a = 14.5697(13), b = 15.8523(16), c = 20.2411(18) Å, α = 86.702(11)°, β = 84.957(11)°, γ = 76.941(11)°, and V = 4533.0(7) Å(3) (2). In the structure of 1 the [V(15)Sb(6)O(42)(H(2)O)](6-) cluster anion is bound to a [Co(N(3)C(5)H(15))(2)](2+) complex via a terminal oxygen atom. In the Co(2+)-centered complex, one of the amine ligands coordinates in tridentate mode and the second one in bidentate mode to form a strongly distorted CoN(5)O octahedron. Similarly, in compound 2 an analogous NiN(5)O complex is joined to the [V(15)Sb(6)O(42)(H(2)O)](6-) anion via the same attachment mode. A remarkable difference between the two compounds is the orientation of the noncoordinated propylamine group leading to intermolecular Sb···O contacts in 1 and to Sb···N interactions in 2. In the solid-state lattices of 1 and 2, two additional [M(N(3)C(5)H(15))(2)](2+) complexes act as countercations and are located between the [{M(N(3)C(5)H(15))(2)}V(15)Sb(6)O(42)(H(2)O)](4-) anions. Between the anions and cations strong N-H···O hydrogen bonds are observed. In both compounds the clusters are stacked along the b axis in an ABAB fashion with cations and water molecules occupying the space between the clusters. Magnetic characterization demonstrates that the Ni(2+) and Co(2+) cations do not significantly couple with the S = 1/2 vanadyl groups. The susceptibility data can be successfully reproduced assuming a distorted ligand field for the Co(2+) ions (1) and an O(h)-symmetric Ni(2+) ligand field (2).

Zeolite 5A Catalyzed Etherification of Diphenylmethanol

ERIC Educational Resources Information Center

Cooke, Jason; Henderson, Eric J.; Lightbody, Owen C.

2009-01-01

An experiment for the synthetic undergraduate laboratory is described in which zeolite 5A catalyzes the room temperature dehydration of diphenylmethanol, (C[subscript 6]H[subscript 5])[subscript 2]CHOH, producing 1,1,1',1'-tetraphenyldimethyl ether, (C[subscript 6]H[subscript 5])[subscript 2]CHOCH(C[subscript 6]H[subscript 5])[subscript 2]. The…

Synthesis and characterization of a series of nickel( ii ) alkoxide precursors and their utility for Ni(0) nanoparticle production

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

Treadwell, LaRico J.; Boyle, Timothy J.; Phelan, W. Adam

2017-02-22

We synthesized a series of nickel(II) aryloxide ([Ni(OAr) 2(py) x]) precursors from an amide-alcohol exchange using [Ni(NR 2) 2] in the presence of pyridine (py). The H-OAr selected were the mono- and di-ortho-substituted 2-alkyl phenols: alkyl = methyl (H-oMP), iso-propyl (H-oPP), tert-butyl (H-oBP) and 2,6-di-alkyl phenols (alkyl = di-iso-propyl (H-DIP), di-tert-butyl (H-DBP), di-phenyl (H-DPhP)). Furthermore, the crystalline products were solved as solvated monomers and structurally characterized as [Ni(OAr) 2(py) x], where x = 4: OAr = oMP (1), oPP (2); x = 3: OAr = oBP (3), DIP (4); x = 2: OAr = DBP (5), DPhP (6). The excitedmore » states (singlet or triplet) and various geometries of 1–6 were identified by experimental UV-vis and verified by computational modeling. Magnetic susceptibility of the representative compound 4 was fit to a Curie Weiss model that yielded a magnetic moment of 4.38(3)μ B consistent with a Ni 2+ center. Compounds 1 and 6 were selected for decomposition studied under solution precipitation routes since they represent the two extremes of coordination. The particle size and crystalline structure were characterized using transmission electron microscopy (TEM) and powder X-ray diffraction (PXRD). Finally, the materials isolated from 1 and 6 were found by TEM to form irregular shape nanomaterials (8–15 nm), which by PXRD were found to be Ni 0 hcp (PDF: 01-089-7129) and fcc (PDF: 01-070-0989), respectively.« less

Structural analysis by reductive cleavage with LiAlH4 of an allyl ether choline-phospholipid, archaetidylcholine, from the hyperthermophilic methanoarchaeon Methanopyrus kandleri

PubMed Central

Nishihara, Masateru; Morii, Hiroyuki; Matsuno, Koji; Ohga, Mami; Stetter, Karl O.; Koga, Yosuke

2002-01-01

A choline-containing phospholipid (PL-4) in Methanopyrus kandleri cells was identified as archaetidylcholine, which has been described by Sprott et al. (1997). The PL-4 consisted of a variety of molecular species differing in hydrocarbon composition. Most of the PL-4 was acid-labile because of its allyl ether bond. The identity of PL-4 was confirmed by thin-layer chromatography (TLC) followed by positive staining with Dragendorff-reagent and fast-atom bombardment–mass spectrometry. A new method of LiAlH4 hydrogenolysis was developed to cleave allyl ether bonds and recover the corresponding hydrocarbons. We confirmed the validity of the LiAlH4 method in a study of the model compound synthetic unsaturated archaetidic acid (2,3-di-O-geranylgeranyl-sn-glycerol-1-phosphate). Saturated ether bonds were not cleaved by the LiAlH4 method. The hydrocarbons formed following LiAlH4 hydrogenolysis of PL-4 were identified by gas–liquid chromatography and mass spectrometry. Four kinds of hydrocarbons with one to four double bonds were detected: 47% of the hydrocarbons had four double bonds; 11% had three double bonds; 14% had two double bonds; 7% had one double bond; and 6% were saturated species. The molecular species composition of PL-4 was also estimated based on acid lability: 77% of the molecular species had two acid-labile hydrocarbons; 11% had one acid-labile and one acid-stable hydrocarbon; and 11% had two acid-stable hydrocarbons. To our knowledge, this is the first report of a specific chemical degradation method for the structural analysis of allyl ether phospholipid in archaea. PMID:15803650

Phase Behavior of Binary Mixture of Heptaethylene Glycol Decyl Ether and Water: Formation of Phase Compound in Solid Phase

PubMed

Nibu; Suemori; Inoue

1997-07-01

Differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT-IR) were used to construct and characterize the phase diagram for a binary mixture of heptaethylene glycol decyl ether (C10 E7 ) and water in the temperature range from -60 to 80°C. Plots of the endothermic peak temperatures obtained by DSC measurements against compositions provided eutectic solid-liquid phase boundaries with a eutectic composition of 34 wt% of H2 O. On the other hand, heat of fusion per unit weight of the mixture changed discretely at the composition corresponding to the "eutectic" composition. Furthermore, the IR spectra obtained for the mixture in the solid phase were well reproduced as a superposition of those for the mixture of 34 wt% H2 O and pure components but were not reproduced by superimposing the spectra obtained for the solid surfactant and ice. These observations indicate that a solid phase compound is formed between C10 E7 and water with a stoichiometry of 1:14 and that the compound and pure components exist as separate phases, rather than the phases separating into surfactant and ice, which would be expected if the C10 E7 /water mixture formed a true eutectic mixture system. It is estimated from the composition corresponding to the phase compounds that two molecules of water per oxyethylene unit are bound to hydrophilic polyoxyethylene chain of C10 E7 to form a hydrated compound.

Bile acids. XLIV, quantitation of bile acids from the bile fistula rat given (4-14C) cholesterol.

PubMed

Siegfried, C M; Doisy, E A; Elliott, W H

1975-01-24

The bile acids derived from [4-14-C]cholesterol administered intracardially to rats with cannulated bile ducts were identified and quantitated. Over a period of 28 days about 90% of the administered 14-C was found in bile of which 73% was retained in the biliary acid fraction. [7beta-3-H]cholic acid, alpha-muri[3beta-3-H]cholic acid, beta-muri[3beta-3-H]cholic acid and litho[3beta-3-H]cholic acid were prepared with specific activities of about 30 muCi/mg by reduction of appropriate ketonic precursors with NaB3H4 and were added to the biliary acid fraction. After separation and purification of the bile acids, cholic, chenodeoxycholic, alpha- and beta-muricholic acids accounted for 70, 16, 7.5 and 6.1%, respectively, of the 14-C in the biliary acid fraction. The specific activities of these isolated 14-C-labeled acids were almost identical. Lithocholic acid accounted for a maximum of 0.2% and ursodeoxycholic acid and 7-oxolithocholic acid could account for no more than 2% of the biliary 14-C. Gas-liquid chromatography on 3% OV-17 of the trimethylsilyl ether derivatives of the methyl esters of the common bile acids of rat bile results in their complete separation and provides a convenient means of estimating the relative proportions of these acids in rat bile. By this method, the relative amounts of the four major acids, cholic, chenodeoxycholic, alpha- and beta-muricholic acids were 63, 20, 8 and 6%, respectively.

Disposition in male volunteers of a subanaesthetic intravenous dose of an oil in water emulsion of 14C-propofol.

PubMed

Simons, P J; Cockshott, I D; Douglas, E J; Gordon, E A; Hopkins, K; Rowland, M

1988-04-01

1. An intravenous dose of 14C-propofol (0.47 mg/kg) administered to six male volunteers was rapidly eliminated with 88% recovered in the urine in 5 days and less than 2% in faeces. 2. The dose was cleared by metabolism with less than 0.3% excreted unchanged. The major metabolites were the glucuronic acid conjugate of propofol and the glucuronic acid and sulphate conjugates of its hydroxylated derivative, 2,6-diisopropyl-1,4-quinol. Propofol glucuronide accounted for about 53% of the urinary radioactivity and was the major metabolite in plasma from 30 min post dose. 3. The blood concentration of propofol declined in a biphasic manner from a maximum mean value of 0.44 microgram/ml, 2 min after injection. The half-lives of the first and second exponential phases, mean values 5 min and 97 min respectively, varied widely among subjects. A proportion of the dose was cleared slowly, probably due to slow release from less well perfused tissues. Propofol accounted for 94% of the total blood radioactivity at 2 min but only about 6% from 3 to 8 h post dose. 4. Propofol has a volume of distribution equivalent to about 3 to 4 times body weight, and a mean total body clearance of 2.2 1/min.

Studies on mass energy-absorption coefficients and effective atomic energy-absorption cross sections for carbohydrates

NASA Astrophysics Data System (ADS)

Ladhaf, Bibifatima M.; Pawar, Pravina P.

2015-04-01

We measured here the mass attenuation coefficients (μ/ρ) of carbohydrates, Esculine (C15H16O9), Sucrose (C12H22O11), Sorbitol (C6H14O6), D-Galactose (C6H12O6), Inositol (C6H12O6), D-Xylose (C5H10O5) covering the energy range from 122 keV up to 1330 keV photon energies by using gamma ray transmission method in a narrow beam good geometry set-up. The gamma-rays were detected using NaI(Tl) scintillation detection system with a resolution of 8.2% at 662 keV. The attenuation coefficient data were then used to obtain the total attenuation cross-section (σtot), molar extinction coefficients (ε), mass-energy absorption coefficients (μen/ρ) and effective (average) atomic energy-absorption cross section (σa,en) of the compounds. These values are found to be in good agreement with the theoretical values calculated based on XCOM data.

Carbonyl Activation by Borane Lewis Acid Complexation: Transition States of H2 Splitting at the Activated Carbonyl Carbon Atom in a Lewis Basic Solvent and the Proton-Transfer Dynamics of the Boroalkoxide Intermediate.

PubMed

Heshmat, Mojgan; Privalov, Timofei

2017-07-06

By using transition-state (TS) calculations, we examined how Lewis acid (LA) complexation activates carbonyl compounds in the context of hydrogenation of carbonyl compounds by H 2 in Lewis basic (ethereal) solvents containing borane LAs of the type (C 6 F 5 ) 3 B. According to our calculations, LA complexation does not activate a ketone sufficiently enough for the direct addition of H 2 to the O=C unsaturated bond; but, calculations indicate a possibly facile heterolytic cleavage of H 2 at the activated and thus sufficiently Lewis acidic carbonyl carbon atom with the assistance of the Lewis basic solvent (i.e., 1,4-dioxane or THF). For the solvent-assisted H 2 splitting at the carbonyl carbon atom of (C 6 F 5 ) 3 B adducts with different ketones, a number of TSs are computed and the obtained results are related to insights from experiment. By using the Born-Oppenheimer molecular dynamics with the DFT for electronic structure calculations, the evolution of the (C 6 F 5 ) 3 B-alkoxide ionic intermediate and the proton transfer to the alkoxide oxygen atom were investigated. The results indicate a plausible hydrogenation mechanism with a LA, that is, (C 6 F 5 ) 3 B, as a catalyst, namely, 1) the step of H 2 cleavage that involves a Lewis basic solvent molecule plus the carbonyl carbon atom of thermodynamically stable and experimentally identifiable (C 6 F 5 ) 3 B-ketone adducts in which (C 6 F 5 ) 3 B is the "Lewis acid promoter", 2) the transfer of the solvent-bound proton to the oxygen atom of the (C 6 F 5 ) 3 B-alkoxide intermediate giving the (C 6 F 5 ) 3 B-alcohol adduct, and 3) the S N 2-style displacement of the alcohol by a ketone or a Lewis basic solvent molecule. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Wide-pore silica-based ether-bonded phases for separation of proteins by high-performance hydrophobic-interaction and size-exclusion chromatography.

PubMed

Miller, N T; Feibush, B; Karger, B L

1984-12-21

This paper examines the use of wide-pore silica-based hydrophilic ether-bonded phases for the chromatographic separation of proteins under mild elution conditions. In particular, ether phases of the following structure identical to Si-(CH2)3-O-(CH2-CH2-O)n-R, where n = 1, 2, 3 and R = methyl, ethyl or n-butyl, have been prepared. These phases can be employed either in high-performance hydrophobic-interaction or size-exclusion chromatography, depending on mobile phase conditions. In the hydrophobic-interaction mode, a gradient of decreasing salt concentration, e.g., from 3 M ammonium sulfate (pH 6.0, 25 degrees C), yields sharp peaks with high mass recovery of active proteins. In this mode, retention can be controlled by salt type and concentration, as well as by column temperature. In the size-exclusion mode, use of medium ionic strength, e.g., 0.5 M ammonium acetate (pH 6.0) yields linear calibration of log (MW[eta]) vs. retention volume. Even at 0.05 M salt concentration, no stationary phase charge effects on protein elution are observed. These bonded-phase columns exhibit good column-to-column reproducibility and constant retention for at least five months of continual use. Examples of the high-performance separation of proteins in both modes are illustrated.

MOF-based catalysts for selective hydrogenolysis of carbon–oxygen ether bonds

DOE PAGES

Stavila, Vitalie; Parthasarathi, Ramakrishnan; Davis, Ryan W.; ...

2015-11-23

We demonstrate that metal–organic frameworks (MOFs) can catalyze hydrogenolysis of aryl ether bonds under mild conditions. Mg-IRMOF-74(I) and Mg-IRMOF-74(II) are stable under reducing conditions and can cleave phenyl ethers containing β-O-4, α-O-4, and 4-O-5 linkages to the corresponding hydrocarbons and phenols. Reaction occurs at 10 bar H 2 and 120 °C without added base. DFT-optimized structures and charge transfer analysis suggest that the MOF orients the substrate near Mg 2+ ions on the pore walls. Ti and Ni doping further increase conversions to as high as 82% with 96% selectivity for hydrogenolysis versus ring hydrogenation. Thus repeated cycling induces nomore » loss of activity, making this a promising route for mild aryl-ether bond scission.« less

Removal of lindane from an aqueous solution by using aminopropyl silica gel-immobilized calix[6]arene.

PubMed

Tor, Ali; Aydin, Mehmet Emin; Aydin, Senar; Tabakci, Mustafa; Beduk, Fatma

2013-11-15

An aminopropyl silica gel-immobilized calix[6]arene (C[6]APS) has been used for the removal of lindane from an aqueous solution in batch sorption technique. The C[6]APS was synthesized with p-tert-butylcalix[6]arene hexacarboxylate derivative and aminopropyl silica gel in the presence of N,N'-diisopropyl carbodiimide coupling reagent. The sorption study was carried out as functions of solution pH, contact time, initial lindane concentration, C[6]APS dosage and ionic strength of solution. The matrix effect of natural water samples on the sorption efficiency of C[6]APS was also investigated. Maximum lindane removal was obtained at a wide pH range of 2-8 and sorption equilibrium was achieved in 2h. The isotherm analysis indicated that the sorption data can be represented by both Langmuir and Freundlich isotherm models. Increasing ionic strength of the solutions increased the sorption efficiency and matrix of natural water samples had no effect on the sorption of lindane. By using multilinear regression model, regression equation was also developed to explain the effects of the experimental variables. Copyright © 2013 Elsevier B.V. All rights reserved.

Applied Mathematical Modules for Use in a Linear Algebra Service Course

DTIC Science & Technology

1990-05-01

H . (1977). Elements of ohysical chemistry. Reading, MA: Addison-Wesley. Rorres , C . & Anton , H . (1984). Applications...k t)r+ v𔃽 A142"+ c -- + C Vt +1 t+ C c tKc cos t 2= 113 123 313 32-3 51 2 V - cu-14sin r t) 232 _E _ VL3 h 3kx3 Cl t + c1 _3 t c + 3 =11-3 12 3 31 6... H " O H H H o 0 0 H H H H H H Ao, //o\\ H HH H

Sealed Gravitational Capillary Viscometry of Dimethyl Ether and Two Next-Generation Alternative Refrigerants

PubMed Central

Cousins, Dylan S.; Laesecke, Arno

2012-01-01

The viscosities of dimethyl ether (DME, C2H6O) and of the fluorinated propene isomers 2,3,3,3-tetrafluoroprop-1-ene (R1234yf, C3H2F4) and trans-1,3,3,3-tetrafluoropropene (R1234ze(E)) were measured in a combined temperature range from 242 K to 350 K at saturated liquid conditions. The instrument was a sealed gravitational capillary viscometer developed at NIST for volatile liquids. Calibration and adjustment of the instrument constant were conducted with n-pentane. The repeatability of the measurements was found to be approximately 1.5 %, leading to a temperature-dependent estimated combined standard uncertainty of the experimental data between 5.7 % at 242 K for dimethyl ether and 2.6 % at 340 K for R1234yf. The measurements were supplemented by ab initio calculations of the molecular size, shape, and charge distributions of the measured compounds. The viscosity results for dimethyl ether were compared with literature data. One other data set measured with a sealed capillary viscometer and exceeding the present results by up to 7 % could be reconciled by applying the vapor buoyancy correction. Then, all data agreed within the estimated uncertainty of the present results. Viscosities for the fluorinated propene isomers deviate up to 4 % from values predicted with the NIST extended corresponding-states model. The viscosities of the two isomers do not scale with their dipole moments. While the measured viscosity of R1234ze(E) with the lower dipole moment is close to that of R134a, the refrigerant to be replaced, that of R1234yf with the higher dipole moment is up to 25 % lower. The viscosity of dimethyl ether is compared with those of water and methanol. PMID:26900526

Crystal structure of (2,4-di-tert-butyl-6-{[(6,6'-dimethyl-2'-oxido-1,1'-biphenyl-2-yl)imino]methyl}phenolato-κ(3) O,N,O')bis(propan-2-olato-κO)titanium(IV).

PubMed

Chen, Liang; Wang, Huiran; Deng, Xuebin

2014-09-01

In the mononuclear Ti(IV) title complex, [Ti(C29H33NO2)(C3H6O)2], the TiNO4 coordination polyhedron comprises an N-atom and two O-atom donors from the dianionic Schiff base ligand and two O-atom donors from monodentate isopropoxide anions. The stereochemistry is distorted trigonal-bipyramidal with the N-donor in an elongated axial site [Ti-N = 2.2540 (17) Å], the O-donors having normal Ti-O bond lengths [1.7937 (14) Å (axial)-1.8690 (14) Å]. In the crystal, C-H⋯π inter-actions link mol-ecules into centrosymmetric dimers.

Preparation of new crosslinking agents and additives for use in polymer electrolyte membranes (PEMs) for fuel cell applications

NASA Astrophysics Data System (ADS)

Zhou, Yangliu

The most commonly used proton conductive membrane in polymer electrolyte membrane fuel cells (PEMFC) and direct methanol fuel cells (DMFC) studies to date is DuPont's NafionRTM, which is a perfluorinated copolymer of tetrafluoroethylene (TFE) and perfluorovinyl ether with a pendant sulfonic acid group. A focus of this work is to find ways to improve the performance of NafionRTM membranes. Crosslinking the TFE chains of fluorinated ionomeric copolymers to improve their thermal and mechanical stability is a proven route to this goal. A straightforward synthetic route to perfluorinated divinyl ethers of the formula CF2=CFO(CF 2)3[OCF(CF3)CF2]mOCF=CF 2 (m = 0-1) has been demonstrated. The compounds CF2=CFO(CF 2)3OCF=CF2 and CF2=CFO(CF2) 3OCF(CF3)CF2OCF=CF2 were prepared and characterized by GC-MS, 13C and 19F NMR, and gas-IR spectroscopy. Synthetic routes to fluorosulfato-tetrafluoropropionyl fluoride [FSO3CF2CF2C(O)F] and difluoromalonyl difluoride [F(O)CCF2C(O)F] with improved yields were found. The second focus of the dissertation was the development of fluorous triarylphosphines for use as new doping materials for the modification of NafionRTM membranes and for use as ligands in catalysts for biphasic catalysis. The synthesis and characterization of a series of new polyhexafluoropropylene oxide derivatives for preparation of fluorous triarylphosphines and phosphonium salts was studied, such as F[CF(CF3)CF2O] 4CF(CF3)CH2CH2I, F[CF(CF3)CF 2O]4CF(CF3)CH=CH2, F[CF(CF3)CF 2O]4CF(CF3) CH2CH2C6H5, and F[CF(CF 3)CF2O]4CF(CF3)CH2CH 2C6H4Br. In a separate study, the photochlorination of 2,2,3,3-tetrafluoro-1-propanol (HCF2CF2CH2OH) and 2,2,3,3-tetrafluoropropyl 2,2,3,3-tetrafluoropropionate [HCF2CF2C(O)OCH2 CF2CF2H] with super diazo blue light (lambda max = 420 nm) were investigated. The photochemical products are different from those obtained under mercury light (lambda = 253.7nm). A new compound ClCF2CF2C(O)OC(H)ClCF2CF2Cl was prepared and characterized by GC-MS, elemental analysis, 1H, 13C and 19F NMR, and gas-IR spectroscopy.

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.

Oxygen-Centered Hexatantalum Tetradecaimido Cluster Complexes

PubMed Central

Krinsky, Jamin L.; Anderson, Laura L.; Arnold, John; Bergman, Robert G.

2008-01-01

The syntheses and characterization of several octahedral hexatantalum cluster compounds of formula (ArN)14Ta6O are described (Ar = Ph, p-MeC6H4, p-MeOC6H4, p-t-BuC6H4, p-BrC6H4, m-ClC6H4). Treatment of Bn3Ta=N-t-Bu (Bn = CH2C6H5) or pentakis(dimethylamido)tantalum with an excess of the appropriate aniline and stoichiometric water or tantalum oxide afforded varying yields of arylimido clusters. The structures of two species were confirmed by X-ray diffraction (XRD), while the identity of the central oxygen atom was elucidated by electrospray mass spectrometry (MS) using 17O/18O-enriched material. The title species are very air- and moisture-sensitive but quite thermally stable in solution. Experimentally determined optical properties and oxidation/reduction potentials, as well as some computational results, indicate that they possess an electronic structure wherein the highest occupied molecular orbitals are ligand-centered, while the lowest unoccupied orbitals are metal-centered and delocalized throughout the tantalum cage. Whereas chemical oxidation resulted in cluster decomposition, reduction with decamethylcobaltocene yielded stable salts of formula [Cp*2Co][(ArN)14Ta6O] (Ar = Ph, Ar = p-MeC6H4). Small-molecule reactivity studies on one of these clusters showed that its imido functionalities are moderately reactive toward oxide donors but inert with respect to metallaheterocycle-forming processes. Clean imido/oxo exchange was observed with aldehydes and ketones, leading cleanly to organic imines with no soluble byproducts being observed. This exchange was also observed with a rhenium oxo compound (generating an imidorhenium complex as the only soluble species). All 14 imido groups were transferred in these reactions, and no mixed-ligand cluster intermediates were ever observed. PMID:18163614

New Acetylene-Terminated Quinoxaline Oligomers

DTIC Science & Technology

1982-03-01

3󈧭 Br, 20.97 Found: C, 62.88; *H, 3.50; Br, 20.83. ( 2 ) (4-Phenylethynyl- 3 ’- bromo )diphenyl ether (6.98 g, 0.02 mol) was dissolved in 150 ml of...I 2 . Govt Accession No. 3 . Recipient’s Catalog Number AFWAL-TR-82-4006 4. Title (and Subtitle) 5. Type of Report & Period Coverec NEW ACETYLENE...displacement of the nitro group of p-nitrobenzil by treatment with the sodium 3 -ethynylphenolate. 1O-CO-Ar-CO-CO-1 + 2 NH2 ) -- H2 > SNHQ2f \\NH2 NH2

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

Yahyaoui, Samia; Rekik, Walid; Laboratoire Sciences Chimiques de Rennes

The crystal structures of 1,4-diazabicyclo[2.2.2]octane (dabco)-templated iron sulfate, (C{sub 6}H{sub 14}N{sub 2})[Fe(H{sub 2}O){sub 6}](SO{sub 4}){sub 2}, were determined at room temperature and at -173 deg. C from single-crystal X-ray diffraction. At 20 deg. C, it crystallises in the monoclinic symmetry, centrosymmetric space group P2{sub 1}/n, Z=2, a=7.964(5), b=9.100(5), c=12.065(5) A, {beta}=95.426(5) deg. and V=870.5(8) A{sup 3}. The structure consists of [Fe(H{sub 2}O){sub 6}]{sup 2+} and disordered (C{sub 6}H{sub 14}N{sub 2}){sup 2+} cations and (SO{sub 4}){sup 2-} anions connected together by an extensive three-dimensional H-bond network. The title compound undergoes a reversible phase transition of the first-order at -2.3 deg. C,more » characterized by DSC, dielectric measurement and optical observations, that suggests a relaxor-ferroelectric behavior. Below the transition temperature, the compound crystallizes in the monoclinic system, non-centrosymmetric space group Cc, with eight times the volume of the ambient phase: a=15.883(3), b=36.409(7), c=13.747(3) A, {beta}=120.2304(8){sup o}, Z=16 and V=6868.7(2) A{sup 3}. The organic moiety is then fully ordered within a supramolecular structure. Thermodiffractometry and thermogravimetric analyses indicate that its decomposition proceeds through three stages giving rise to the iron oxide. - Graphical abstract: The new dabcodiium hexaaquairon(II) bis(sulfate), (C{sub 6}H{sub 14}N{sub 2})[Fe(H{sub 2}O){sub 6}](SO{sub 4}){sub 2}, was prepared and characterized. It exhibits a supramolecular structure and undergoes a reversible order-disorder phase transition at -2.3 deg. C.« less

Synthesis, anticancer activity, and iron affinity of the Actinoplanes metabolite 7,8-dihydroxy-1-methylnaphtho[2,3-c]furan-4,9-dione.

PubMed

Breyer, Sandra; Effenberger-Neidnicht, Katharina; Knauer, Sebastian; Schobert, Rainer

2011-02-01

The first synthesis of 7,8-dihydroxy-1-methylnaphtho[2,3-c]furan-4,9-dione (1), an isofuranonaphthoquinone produced by an Actinoplanes strain is described. Lactone ring opening of 6-methylfuro[3,4-c]furan-1(3H)-one (4) with ortho-lithiated veratrole (3), oxidation of product alcohol 5, and Friedel-Crafts acylation of the resulting aroylcarboxylic acid 7 afforded the mono methyl ether 2 of the target compound. The latter was obtained by demethylation of 2 with BBr(3) in 14% overall yield. While mono ether 2 was distinctly more cytotoxic than catechol 1 against a panel of five cancer cell lines, only the latter showed a siderophore-like binding affinity for Fe(III) with a complex dissociation constant K(D) of approximately 10(-29) M(3) (pM = 25.9). Copyright © 2010 Elsevier Ltd. All rights reserved.

The hydrothermal decomposition of calcium monosulfoaluminate 14-hydrate to katoite hydrogarnet and β-anhydrite: An in-situ synchrotron X-ray diffraction study

NASA Astrophysics Data System (ADS)

Meller, Nicola; Kyritsis, Konstantinos; Hall, Christopher

2009-10-01

We apply in-situ synchrotron X-ray diffraction to study the transformation of calcium monosulfoaluminate 14-hydrate Ca 4Al 2O 6(SO 4)·14H 2O [monosulfate-14] to hydrogarnet Ca 3Al 2(OH) 12 on the saturated water vapor pressure curve up to 250 °C. We use an aqueous slurry of synthetic ettringite Ca 6Al 2(SO 4) 3(OH) 12·26H 2O as the starting material; on heating, this decomposes at about 115 °C to form monosulfate-14 and bassanite CaSO 4·0.5H 2O. Above 170 °C monosulfate-14 diffraction peaks slowly diminish in intensity, perhaps as a result of loss of crystallinity and the formation of an X-ray amorphous meta-monosulfate. Hydrogarnet nucleates only at temperatures above 210 °C. Bassanite transforms to β-anhydrite (insoluble anhydrite) at about 230 °C and this transformation is accompanied by a second burst of hydrogarnet growth. The transformation pathway is more complex than previously thought. The mapping of the transformation pathway shows the value of rapid in-situ time-resolved synchrotron diffraction.

Zinc(II) complexes with heterocyclic ether, acid and amide. Crystal structure, spectral, thermal and antibacterial activity studies

NASA Astrophysics Data System (ADS)

Jabłońska-Wawrzycka, Agnieszka; Rogala, Patrycja; Czerwonka, Grzegorz; Hodorowicz, Maciej; Stadnicka, Katarzyna

2016-02-01

The reaction of zinc salts with heterocyclic ether (1-ethoxymethyl-2-methylimidazole (1-ExMe-2-MeIm)), acid (pyridine-2,3-dicarboxylic acid (2,3-pydcH2)) and amide (3,5-dimethylpyrazole-1-carboxamide (3,5-DMePzCONH2)) yielded three new zinc complexes formulated as [Zn(1-ExMe-2-MeIm)2Cl2] 1, fac-[Zn(H2O)6][Zn(2,3-pydcH)3]22 and [Zn(3,5-DMePz)2(NCO)2] 3. Complexes of 1 and 3 are four-coordinated with a tetrahedron as coordination polyhedron. However, compound 2 forms an octahedral cation-anion complex. The complex 3 was prepared by eliminating of the carboxamide group from the ligand and then the 3,5-dimethylpyrazole (3,5-DMePz) and isocyanates formed were employed as new ligands. The IR and X-ray studies have confirmed a bidentate fashion of coordination of the 2,3-pydcH and monodentate fashion of coordination of the 1-ExMe-2-MeIm and 3,5-DMePz to the Zn(II) ions. The crystal packing of Zn(II) complexes are stabilized by intermolecular classical hydrogen bonds of O-H⋯O and N-H⋯O types. The most interesting feature of the supramolecular architecture of complexes is the existence of C-H⋯O, C-H⋯Cl and C-H⋯π interactions and π⋯π stacking, which also contributes to structural stabilisation. The correlation between crystal structure and thermal stability of zinc complexes is observed. In all compounds the fragments of ligands donor-atom containing go in the last steps. Additionally, antimicrobial activities of compounds were carried out against certain Gram-positive and Gram-negative bacteria and counts of CFU (colony forming units) were also determined. The achieved results confirmed a significant antibacterial activity of some tested zinc complexes. On the basis of the Δ log CFU values the antibacterial activity of zinc complexes follows the order: 3 > 2 > 1. Influence a number of N-donor atoms in zinc environment on antibacterial activity is also observed.

Three closely related 4,5,6,7-tetrahydro-1H-pyrazolo[4,3-c]pyridines: synthesis, molecular conformations and hydrogen bonding in zero, one and two dimensions.

PubMed

Sagar, Belakavadi K; Harsha, Kachigere B; Yathirajan, Hemmige S; Rangappa, Kanchugarakoppal S; Rathore, Ravindranath S; Glidewell, Christopher

2017-03-01

In each of 1-(4-fluorophenyl)-5-methylsulfonyl-3-[4-(trifluoromethyl)phenyl]-4,5,6,7-tetrahydro-1H-pyrazolo[4,3-c]pyridine, C 21 H 19 F 4 N 3 O 2 S, (I), 1-(4-chlorophenyl)-5-methylsulfonyl-3-[4-(trifluoromethyl)phenyl]-4,5,6,7-tetrahydro-1H-pyrazolo[4,3-c]pyridine, C 21 H 19 ClF 3 N 3 O 2 S, (II), and 1-(3-methylphenyl)-5-methylsulfonyl-3-[4-(trifluoromethyl)phenyl]-4,5,6,7-tetrahydro-1H-pyrazolo[4,3-c]pyridine, C 22 H 22 F 3 N 3 O 2 S, (III), the reduced pyridine ring adopts a half-chair conformation with the methylsulfonyl substituent occupying an equatorial site. Although compounds (I) and (II) are not isostructural, having the space groups Pbca and P2 1 2 1 2 1 , respectively, their molecular conformations are very similar, but the conformation of compound (III) differs from those of (I) and (II) in the relative orientation of the N-benzyl and methylsulfonyl substituents. In compounds (II) and (III), but not in (I), the trifluoromethyl groups are disordered over two sets of atomic sites. Molecules of (I) are linked into centrosymmetric dimers by C-H...π(arene) hydrogen bonds, molecules of (II) are linked by two C-H...O hydrogen bonds to form ribbons of R 3 3 (18) rings, which are themselves further linked by a C-Cl...π(arene) interaction, and a combination of C-H...O and C-H...π(arene) hydrogen bonds links the molecules of (III) into sheets. Comparisons are made with the structures of some related compounds.

Persubstituted p-benzoquinone monoxime alkyl ethers and their molecular structure

NASA Astrophysics Data System (ADS)

Slaschinin, D. G.; Alemasov, Y. A.; Ilushkin, D. I.; Sokolenko, W. A.; Tovbis, M. S.; Kirik, S. D.

2012-05-01

Theoretical and experimental approaches were applied for the investigation of the reactivity of persubstituted 4-nitrosophenols in the reaction with alkyl iodides, in particular the potassium salt of 2,6-di(alkoxycarbonyl)-3,5-dimethyl-4-nitrosophenol. Hartre-Fock calculations showed that the anion negative charge was located mostly on the oxygen of hydroxyl group, while estimation of the total energy of the alkylated products pointed out the benefit of alkylation on the oxygen atom of the nitroso group yielding p-benzoquinone monoxime alkyl ethers. Methylation and ethylation of persubstituted nitrosophenols were carried out. The products obtained were investigated using X-ray diffraction, 1Н NMR spectroscopy and mass spectrometry. The crystal structure of the methyl ether of 2,6-di(alkoxycarbonyl)-3,5-dimethyl-1,4-benzoquinone-1-oxime (С15H19NO6) (I) was determined by the X-ray powder diffraction technique. The unit cell parameters were: a = 7.3322(6) Å, b = 10.5039(12) Å, c = 21.1520(20) Å, β = 93.742(6)°, V = 1625.58(2) Å3Z = 4, Sp.Gr. P21/c. The structure modeling was made in direct space by the Monte-Carlo approach using rigid and soft restrictions. The structure refinement was completed by the Rietveld method. It was established that the alkylation occurred on the oxygen atom of the nitroso group. The molecules (I) in the crystal structure were packed in columns along the axis a with pairwise convergence in a column up to the distance of 3.63 Å due to a 180° turn of every second molecule around the column axis. In the molecular structure the methyloxime group was oriented in the benzene plane and had π-conjugation with the ring. The ethoxycarbonyl groups were turned nearly perpendicular to the ring. Other compounds obtained had the structure of the alkyl ethers of 1.4-benzoquinone-1-oxime, which was proved by 1Н NMR spectroscopy and mass-spectrometry.

Responses of the L51781Y tk/sup +//tk/sup -/ mouse lymphoma cell forward mutation assay: III. 72 coded chemicals

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

McGregor, D.B.; Brown, A.; Cattanach, P.

Seventy-two chemicals were tested for their mutagenic potential in the L51781Y tk/sup +///sup -/ mouse lymphoma cell forward mutation assay, using procedures based upon those described previously. Cultures were exposed to the chemicals for 4 hr, then cultured for 2 days before planting in soft agar with or without trifluorothymidine (TFT), 3 ..mu..g/ml. The chemicals were tested at least twice. Significant responses were obtained with allyl isothiocyanate, p-benzoquinone dioxime, benzyl acetate, 2-biphenylamine HCl, bis(2-chloro-1-methylethyl)ether, cadmium chloride, chlordane, chlorobenzene, chlorobenzilate, 2-chloroethanol, chlorothalonil, cytarabine x HCl, p,p'-DDE, diazinon, 2,6-dichloro-p-phenylenediamine, N,N-diethylthiourea, diglycidylresorcinol ether, 2,4-dimethoxy aniline x HCl, disperse yellow 3, endosulfan, 1,2-epoxyhexadecane, ethylmore » acrylate, ethyl benzene, ethylene thiourea, F D and C yellow Number 6, furan, heptachlor, isophorone, mercuric chloride, 4,4'-methylenedianiline x 2 HCl, methyl viologen, nickel sulfate x 6H/sub 2/O, 4,4'-oxydianiline, pentachloroethane, piperonyl butoxide, propyl gallate, quinoline, rotenone, 2,4,5,6-tetrachloro-4-nitro-anisole, 1,1,1,2-tetrachloroethane, trichlorfon, 2,4,6-trichlorophenol, 2,4,5-trimethoxybenzaldehyde, 1,1,3-trimethyl-2-thiourea, 1-vinyl-3-cyclopetene dioxide, vinyl toluene, and ziram. The assay was incapable of providing a clear indication of whether some chemicals were mutagens; these benzyl alcohol, 1,4-dichlorobenzene, phenol, succinic acid-2,2-dimethyl hydrazide, and toluene.« less

Sol-gel synthesis of K{sub 3}InF{sub 6} and structural characterization of K{sub 2}InC{sub 10}O{sub 10}H{sub 6}F{sub 9}, K{sub 3}InC{sub 12}O{sub 14}H{sub 4}F{sub 18} and K{sub 3}InC{sub 12}O{sub 12}F{sub 18}

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

Labeguerie, Jessica; Gredin, Patrick; Marrot, Jerome

2005-10-15

K{sub 3}InF{sub 6} is synthesized by a sol-gel route starting from indium and potassium acetates dissolved in isopropanol in the stoichiometry 1:3, with trifluoroacetic acid as fluorinating agent. The crystal structures of the organic precursors were solved by X-ray diffraction methods on single crystals. Three organic compounds were isolated and identified: K{sub 2}InC{sub 10}O{sub 10}H{sub 6}F{sub 9}, K{sub 3}InC{sub 12}O{sub 14}H{sub 4}F{sub 18} and K{sub 3}InC{sub 12}O{sub 12}F{sub 18}. The first one, deficient in potassium in comparison with the initial stoichiometry, is unstable. In its crystal structure, acetate as well as trifluoroacetate anions are coordinated to the indium atom. Themore » two other precursors are obtained, respectively, by quick and slow evaporation of the solution. They correspond to the final organic compounds, which give K{sub 3}InF{sub 6} by decomposition at high temperature. The crystal structure of K{sub 3}InC{sub 12}O{sub 14}H{sub 4}F{sub 18} is characterized by complex anions [In(CF{sub 3}COO){sub 4}(OH{sub x}){sub 2}]{sup (5-2x)-} and isolated [CF{sub 3}COOH{sub 2-x}]{sup (x-1)-} molecules with x=2 or 1, surrounded by K{sup +} cations. The crystal structure of K{sub 3}InC{sub 12}O{sub 12}F{sub 18} is only constituted by complex anions [In(CF{sub 3}COO){sub 6}]{sup 3-} and K{sup +} cations. For all these compounds, potassium cations ensure only the electroneutrality of the structure. IR spectra of K{sub 2}InC{sub 10}O{sub 10}H{sub 6}F{sub 9} and K{sub 3}InC{sub 12}O{sub 12}F{sub 18} were also performed at room temperature on pulverized crystals.« less

Stereoselective synthesis of novel thioglycosyl heterocycles

NASA Astrophysics Data System (ADS)

El Ashry, El Sayed H.; Awad, Laila F.; Al Moaty, Mohamed N. Abd; Ghabbour, Hazem A.; Barakat, Assem

2018-01-01

In this work, the synthesis of novel 1,2,4-triazole thioglycoside heterocycles 4, 5, and 8 were achieved by the reaction of 1,2,3,4,6-penta-O-acetyl-β-D-glucopyranose (2) and galactopyranose (3) with 4-((4-arylidene)amino)-5-methyl-1,2,4-triazole-3-thiol derivatives 1 and 6 in the presence of boron trifluoride etherate (BF3·Et2O) as a promoter under nitrogen in CH2Cl2. Exclusive β-stereoselectivity of the formed glycosidic bond was confirmed by X-ray analysis of 4 as well as its spectral data. Different stereoselectivities were observed when the acceptor 9, having an ortho phenolic OH group, was coupled with the donors 2 or 3, under the same reaction conditions. Similarly, treatment of a mixture of 1-O-acetyl-2,3,5-tri-O-benzoyl-β-D-ribofuranose (16) and the thiol acceptors 1 and 15 afforded the β-thioribofuranosides 17 and 18, respectively. The β-stereoselectivity of the reaction was confirmed by 1H, 13C, 1Hsbnd 1H 2D, and 1Hsbnd 13C 2D NMR spectral analysis.

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.

The structures of 1,4-diaryl-5-trifluoromethyl-1H-1,2,3-triazoles related to J147, a drug for treating Alzheimer's disease.

PubMed

Farrán, M Ángeles; Bonet, M Ángels; Claramunt, Rosa M; Torralba, M Carmen; Alkorta, Ibon; Elguero, José

2018-04-01

J147 [N-(2,4-dimethylphenyl)-2,2,2-trifluoro-N'-(3-methoxybenzylidene)acetohydrazide] has recently been reported as a promising new drug for the treatment of Alzheimer's disease. The X-ray structures of seven new 1,4-diaryl-5-trifluoromethyl-1H-1,2,3-triazoles, namely 1-(3,4-dimethylphenyl)-4-phenyl-5-trifluoromethyl-1H-1,2,3-triazole (C 17 H 14 F 3 N 3 , 1), 1-(3,4-dimethylphenyl)-4-(3-methoxyphenyl)-5-trifluoromethyl-1H-1,2,3-triazole (C 18 H 16 F 3 N 3 O, 2), 1-(3,4-dimethylphenyl)-4-(4-methoxyphenyl)-5-trifluoromethyl-1H-1,2,3-triazole (C 18 H 16 F 3 N 3 O, 3), 1-(2,4-dimethylphenyl)-4-(4-methoxyphenyl)-5-trifluoromethyl-1H-1,2,3-triazole (C 18 H 16 F 3 N 3 O, 4), 1-[2,4-bis(trifluoromethyl)phenyl]-4-(3-methoxyphenyl)-5-trifluoromethyl-1H-1,2,3-triazole (C 18 H 10 F 9 N 3 O, 5), 1-(3,4-dimethoxyphenyl)-4-(3,4-dimethoxyphenyl)-5-trifluoromethyl-1H-1,2,3-triazole (C 19 H 18 F 3 N 3 O 4 , 6) and 3-[4-(3,4-dimethoxyphenyl)-5-(trifluoromethyl)-1H-1,2,3-triazol-1-yl]phenol (C 17 H 14 F 3 N 3 O 3 , 7), have been determined and compared to that of J147. B3LYP/6-311++G(d,p) calculations have been performed to determine the potential surface and molecular electrostatic potential (MEP) of J147, and to examine the correlation between hydrazone J147 and the 1,2,3-triazoles, both bearing a CF 3 substituent. Using MEPs, it was found that the minimum-energy conformation of 4, which is nearly identical to its X-ray structure, is closely related to one of the J147 seven minima.

Lignans isolated from Campylotropis hirtella (Franch.) Schindl. decreased prostate specific antigen and androgen receptor expression in LNCaP cells.

PubMed

Han, Hui-Ying; Wang, Xiang-Hong; Wang, Nai-Li; Ling, Ming-Tat; Wong, Yong-Chuan; Yao, Xin-Sheng

2008-08-27

Accumulating epidemiological data suggest that Asian men have lower incidences of prostate cancer and benign prostate hyperplasia (BPH) compared with American and European populations and may have benefited from their higher intake of phytoestrogens in their diet. However, how these phytochemicals affect prostatic diseases is still unclear. In this study, we isolated six lignans from a plant, Campylotropis hirtella (Franch.) Schindl., which has been used as a folk medicine for treatment of BPH in China, through bioassay guided fractionation. They were dehydrodiconiferyl alcohol (C1), 4-[(-6-hydroxy-2,3-dihydro-1-benzofuran-3-yl)methyl]-5-methoxybenzene-1,3-diol (C2), erythro-guaiacylglycerol-beta-O-4'-coniferyl ether (C3), threo-guaiacylglycerol-beta-O-4'-coniferyl ether (C4), secoisolariciresinol (C5), and prupaside (C6), where C2 was identified as a new lignan analog. Their IC50 values for inhibition of prostate specific antigen (PSA) secretion were 19, 45, 110, 128, 137, and 186 microM, respectively, from C1 to C6 in LNCaP cells. Further study showed that C1-5 down-regulated cellular PSA expression and C1-4 also decreased androgen receptor (AR) expression in LNCaP cells. Furthermore, we investigated the proapoptotic effect of C1 on LNCaP cells. The active forms of caspase 3 associated with the specific proteolysis of poly (ADP-ribose) polymerase (PARP) were detected, and the antiapoptotic protein Bcl-2 was down-regulated after the treatment with C1. These results collectively indicated that these lignans may have chemopreventive or therapeutic actions for prostate cancer through suppressing AR signaling pathway and inducing apoptosis.

Phytotoxicity of brominated diphenyl ether-47 (BDE-47) and its hydroxylated and methoxylated analogues (6-OH-BDE-47 and 6-MeO-BDE-47) to maize (Zea mays L.).

PubMed

Xu, Xuehui; Huang, Honglin; Wen, Bei; Wang, Sen; Zhang, Shuzhen

2015-03-16

Polybrominated diphenyl ethers (PBDEs), methoxylated PBDEs (MeO-PBDEs), and hydroxylated PBDEs (OH-PBDEs) are widely found in various environmental media, which is of concern given their biological toxicity. In this study, the phytotoxicities of BDE-47, 6-MeO-BDE-47, and 6-OH-BDE-47 to maize (Zea mays L.) were investigated by an in vivo exposure experiment. Results showed that BDE-47, 6-MeO-BDE-47, and 6-OH-BDE-47 inhibited seed germination and seedling development, and elevated malondialdehyde (MDA), carbonyl groups, and phosphorylated histone H2AX levels in maize roots, suggesting the inducement of lipid peroxidation, protein carbonylation, and DNA damage to maize. Exposure to BDE-47, 6-MeO-BDE-47, and 6-OH-BDE-47 caused the overproduction of H2O2, O2(•-), and •OH, and elevated the activities of antioxidant enzymes in the roots. In addition, 6-OH-BDE-47 caused more severe damage and reactive oxygen species (ROS) generation in maize than did BDE-47 and 6-MeO-BDE-47. These results demonstrated the phytotoxicities of BDE-47, 6-OH-BDE-47, and 6-MeO-BDE-47 to maize, and clarified that overproduction of ROS was the key mechanism leading to toxicity. This study offers useful information for a more comprehensive understanding of the environmental behaviors and toxicities of PBDEs, MeO-PBDEs, and OH-PBDEs.

Hexafluorobenzene in comparison with perfluoro-15-crown-5-ether for repeated monitoring of oxygenation using 19F MRI in a mouse model.

PubMed

Mignion, Lionel; Magat, Julie; Schakman, Olivier; Marbaix, Etienne; Gallez, Bernard; Jordan, Bénédicte F

2013-01-01

Hexafluorobenzene (HFB) and perfluoro-15-crown-5-ether (15C5) were compared as fluorine reporter probes of tissue oxygenation using (19)F MRI for dynamic assessment of muscle oxygenation, with special focus on muscle tissue toxicity of the probes, and consecutive alteration of animal behavior. The latter were also compared in terms of sensitivity to changes in oxygenation as well as of signal-to-noise ratio for accurate pO(2) measurements. For that purpose, mouse muscles were imaged at 11.7 T, at 2- and 36-h after intramuscular injection of HFB or 15C5. Histological analysis of the muscle tissue revealed a lack of toxicity for 15C5 from 2 up to 36-h postinjection, whereas HFB induced tissue necrosis, blood clots and thrombosis as soon as 24-h postinjection. This muscle toxicity led to a limitation in mice mobility 24-h after injection of HFB as evidenced by behavioral testing (open-field, grip strength, and catwalk tests), which was not the case after 15C5 intramuscular injection. Finally, pO(2) measurements assessed 2-h postinjection showed consistent values with both probes, evidencing cross-validation of the (19)F MRI oximetry technique for acute measurements. However, the measurement at 36-h was hampered for HFB, which showed significant lower values of muscle pO(2), whereas 15C5 was able to reliably assess muscle pO(2) at 36-h postinjection. Copyright © 2012 Wiley Periodicals, Inc.

A four-component coupling reaction of carbon dioxide, amines, cyclic ethers and 3-triflyloxybenzynes for the synthesis of functionalized carbamates.

PubMed

Xiong, Wenfang; Qi, Chaorong; Cheng, Ruixiang; Zhang, Hao; Wang, Lu; Yan, Donghao; Jiang, Huanfeng

2018-04-27

A novel four-component coupling reaction of carbon dioxide, amines, cyclic ethers and 3-triflyloxybenzynes has been developed for the first time, providing an efficient method for the synthesis of a series of functionalized carbamate derivatives in moderate to high yields. The process proceeds under mild, transition metal-free and fluoride-free conditions, leading to the formation of two new C-O bonds, one new C-N bond and one C-H bond in a single step.

Influence of iron and copper oxides on polychlorinated diphenyl ether formation in heterogeneous reactions.

PubMed

Liu, Wenxia; Shen, Lianfeng; Zhang, Fawen; Liu, Wenbin; Zheng, Minghui; Yang, Xitian

2013-08-01

Polychlorinated diphenyl ether (PCDE) has attracted great attention recently as an important type of environmental pollutant. The influence of iron and copper oxides on formation of PCDEs was investigated using laboratory-scale flow reactors under air and under nitrogen at 350 °C, a temperature corresponding to the post-combustion zone of a municipal solid waste incinerator. The results show that the 2,2',3,4,4',5,5',6-otachlorodiphenyl ether (OCDE) formed from the condensation of pentachlorophenol (PCP) and 1,2,4,5-tetrachlorobenzene (Cl4Bz) is the predominant congener formed on the SiO2/Fe2O3 surface with and without oxygen. This indicated that HCl elimination between PCP and 1,2,4,5-Cl4Bz molecules formed 2,2',3,4,4',5,5',6-OCDE in the presence of Fe2O3. On the other hand, decachlorodiphenyl ether, nonachlorodiphenyl ether, and OCDE were the dominant products on the SiO2/CuO surface without oxygen, although the 2,2',3,4,4',5,5',6-OCDE was the dominant product on the SiO2/CuO surface with oxygen. Therefore, the presence of Fe2O3 and CuO influences the formation and homologue distribution of PCDEs, which shifted towards the lower chlorinated species. Fe2O3 can promote both the condensation and dechlorination reaction without oxygen. On the contrary, with oxygen, Fe2O3 suppresses the condensation of chlorobenzene and chlorophenol to form PCDEs and polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs). CuO can increase the formation of lower chlorinated PCDEs and PCDDs without oxygen. In conclusion, the different fly ash components have a major influence on PCDE emissions.

3,4-Dimethyl-1-phenyl­pyrano[2,3-c]pyrazol-6(1H)-one

PubMed Central

Ahmad, Neman; Tahir, M. Nawaz; Khan, Misbahul Ain; Ather, Abdul Qayyum; Khan, Muhammad Naeem

2011-01-01

In the title compound, C14H12N2O2, the dihedral angle between the phenyl ring and the 3,4-dimethyl­pyrano[2,3-c]pyrazol-6(1H)-one system is 7.28 (6)°. An intra­molecular C—H⋯O inter­action generates an S(6) ring. In the crystal, the mol­ecules are linked by C—H⋯O hydrogen bonds, forming C(8) chains. C–H⋯π and π–π inter­actions [centroid–centroid separation = 3.6374 (12) Å] further consolidate the packing. PMID:21754037

Radical Cationic Pathway for the Decay of Ionized Glyme Molecules in Liquid Solution.

PubMed

Taletskiy, Konstantin S; Borovkov, Vsevolod I; Schegoleva, Lyudmila N; Beregovaya, Irina V; Taratayko, Andrey I; Molin, Yuriy N

2015-11-12

Chemical stability of primary radical cations (RCs) generated in irradiated matter determines substantially the radiation resistance of organic materials. Transformations of the RCs of the glyme molecules, R(-O-CH2-CH2-)nO-R (R = CH3, n = 1-4) has been studied on the nanosecond time scale by measuring the magnetic field effects in the recombination fluorescence from irradiated liquid solutions of the glymes. In all cases, the RCs observed were different from that expected for the primary ones and revealed very similar hyperfine couplings independent of the poly(ethylene oxide) chain length and of the substitution of terminal methyl groups by C2H5 or CH2CH2Cl, as has been shown with diglyme as an example. Quantum chemical analysis of possible chemical transformations for the monoglyme RC as a model system allowed us to discover the reaction pathway yielding the methyl vinyl ether RC. The pathway involves intramolecular proton transfer followed by C-O bond cleavage. Only one (-O-CH2-CH2-O-) fragment is involved in this transformation, which is nearly barrierless due to the catalytic effect of adjacent glyme molecules. The rapid formation of the methyl vinyl ether RC in the irradiated monoglyme was confirmed by the numerical simulation of the experimental curves of the time-resolved magnetic field effect. These findings suggest that the R'-O-CH═CH2(•+) formation is a typical decay pathway for the primary RCs in irradiated liquid glymes.

Syntheses, structures and characterization of isomorphous CoII and NiII coordination polymers based on 2-[(1H-imidazol-1-yl)methyl]-6-methyl-1H-benzimidazole and benzene-1,4-dicarboxylate.

PubMed

Huang, Qiu Ying; Zhao, Yang; Meng, Xiang Ru

2017-08-01

Careful choice of the organic ligands is one of the most important parameters in the rational design and synthesis of coordination polymers. Aromatic polycarboxylates have been widely used in the preparation of metal-organic polymers since they can utilize various coordination modes to form diverse structures and can act as hydrogen-bond acceptors and donors in the assembly of supramolecular structures. Nitrogen-heterocyclic organic compounds have also been used extensively as ligands for the construction of polymers with interesting structures. In the polymers catena-poly[[[diaquabis{2-[(1H-imidazol-1-yl)methyl]-6-methyl-1H-benzimidazole-κN 3 }cobalt(II)]-μ 2 -benzene-1,4-dicarboxylato-κ 2 O 1 :O 4 ] dihydrate], {[Co(C 8 H 4 O 4 )(C 12 H 11 N 4 ) 2 (H 2 O) 2 ]·2H 2 O} n , (I), and catena-poly[[[diaquabis{2-[(1H-imidazol-1-yl)methyl]-6-methyl-1H-benzimidazole-κN 3 }nickel(II)]-μ 2 -benzene-1,4-dicarboxylato-κ 2 O 1 :O 4 ] dihydrate], {[Ni(C 8 H 4 O 4 )(C 12 H 11 N 4 ) 2 (H 2 O) 2 ]·2H 2 O} n , (II), the Co II or Ni II ion lies on an inversion centre and exhibits a slightly distorted octahedral coordination geometry, coordinated by two N atoms from two imidazole rings and four O atoms from two monodentate carboxylate groups and two water molecules. The dicarboxylate ligands bridge metal ions forming a polymeric chain. The 2-[(1H-imidazol-1-yl)methyl]-6-methyl-1H-benzimidazole ligands coordinate to the Co II or Ni II centres in monodentate modes through an imidazole N atom and are pendant on opposite sides of the main chain. The two structures are isomorphous. In the crystal, the one-dimensional chains are further connected through O-H...O, O-H...N and N-H...O hydrogen bonds, leading to a three-dimensional supramolecular architecture. In addition, the IR spectroscopic properties, PXRD patterns, thermogravimetric behaviours and fluorescence properties of both polymers have been investigated.

Resistance and Stock Propulsion on the High Speed Sealift (HSS) Hybrid Contra-Rotating Shaft-Pod (HCRSP) Concept, Model 5653-3A

DTIC Science & Technology

2008-09-01

8217 I l ALW N- N OD0 OH (N IV’ W 00 H- -W’ 0) (Nq Ht DC1 C’w H HH HrHir-1r-1C4(N N m 0H 0 E rr.. .1 0 29H0UH WP 4t or -u HH H HN wo)w i o I CW0W M IDID01...l C4 H NA a) N’ N) ~ N C14 N m m U m (0 a) m H (N U M m v IV -IN . . . . . . $-Na A F- " (N -l(04" 04 -4 -4" Ht -4 F- e~N rlN m H 0 CmN’rCr m ) m mmm...H O H-4 LALANOLAHCO)a)C"la)iL. . .N.a. .OHA.. . H.N.N.O.N.l. . 0HH H H H kel( N O L A 0 M m.) L ( 0 1 WmmN r 1 4 4w o oW W 6m o ( o,WmL A6L A 6L A L

Synthesis, characterization and DNA-binding studies of mono and heterobimetallic complexes Cu sbnd Sn 2/Zn sbnd Sn 2 and their DNA cleavage activity

NASA Astrophysics Data System (ADS)

Arjmand, Farukh; Sayeed, Fatima

2010-02-01

Heterobimetallic complexes C 6H 24N 4O 6CuSn 2Cl 63, C 6H 24N 4O 6ZnSn 2Cl 64 have been synthesized from their monometallic analogs C 6H 16N 4O 2CuCl 21, C 6H 16N 4O 2ZnCl 22, and were characterized by various spectroscopic and analytical methods. The complexes 1-4 reveal an octahedral geometry for both central metal ions Cu/Zn as well as for Sn metal ion. The interaction of complexes 1-4 with CT-DNA, were investigated by using absorption, emission, cyclic voltammetry, viscometry and DNA cleavage studies. The emission quenching of 3 and 4 by [Fe(CN) 6] 4- depressed greatly when bound to CT-DNA. The results of spectroscopic, viscometric and cyclic voltammetry of complexes 3 and 4 revealed electrostatic mode of binding of the complexes with CT-DNA. These results revealed that 4 bind more avidly in comparison to 3 with CT-DNA. Gel electrophoresis of DNA with complexes 3 and 4 demonstrated that the complexes exhibit excellent cleavage activity under physiological conditions.

Crystal structures of five (2-chloro­quinolin-3-yl)methyl ethers: supra­molecular assembly in one and two dimensions mediated by hydrogen bonding and π–π stacking

PubMed Central

Sowmya, Haliwana B. V.; Suresha Kumara, Tholappanavara H.; Gopalpur, Nagendrappa; Jasinski, Jerry P.; Millikan, Sean P.; Yathirajan, Hemmige S.; Glidewell, Christopher

2015-01-01

In the mol­ecules of the title compounds, methyl 5-bromo-2-[(2-chloro­quinolin-3-yl)meth­oxy]benzoate, C18H13BrClNO3, (I), methyl 5-bromo-2-[(2-chloro-6-methyl­quinolin-3-yl)meth­oxy]benzoate, C19H15BrClNO3, (II), methyl 2-[(2-chloro-6-methyl­quinolin-3-yl)meth­oxy]benzoate, C19H16ClNO3, (III), which crystallizes with Z′ = 4 in space group P212121, and 2-chloro-3-[(naphthalen-1-yl­oxy)meth­yl]quinoline, C20H14ClNO, (IV), the non-H atoms are nearly coplanar, but in {5-[(2-chloro­quinolin-3-yl)meth­oxy]-4-(hy­droxy­meth­yl)-6-methyl­pyridin-3-yl}methanol, C18H17ClN2O3, (V), the planes of the quinoline unit and of the unfused pyridine ring are almost parallel, although not coplanar. The mol­ecules of (I) are linked by two independent π–π stacking inter­actions to form chains, but there are no hydrogen bonds present in the structure. In (II), the mol­ecules are weakly linked into chains by a single type of π–π stacking inter­action. In (III), three of the four independent mol­ecules are linked by π–π stacking inter­actions but the other mol­ecule does not participate in such inter­actions. Weak C—H⋯O hydrogen bonds link the mol­ecules into three types of chains, two of which contain just one type of independent mol­ecule while the third type of chain contains two types of mol­ecule. The mol­ecules of (IV) are linked into chains by a C—H⋯π(arene) hydrogen bond, but π–π stacking inter­actions are absent. In (V), there is an intra­molecular O—H⋯O hydrogen bond, and mol­ecules are linked into sheets by a combination of O—H⋯N hydrogen bonds and π–π stacking inter­actions. PMID:26090133

Synthesis of ketones from biomass-derived feedstock.

PubMed

Meng, Qinglei; Hou, Minqiang; Liu, Huizhen; Song, Jinliang; Han, Buxing

2017-01-31

Cyclohexanone and its derivatives are very important chemicals, which are currently produced mainly by oxidation of cyclohexane or alkylcyclohexane, hydrogenation of phenols, and alkylation of cyclohexanone. Here we report that bromide salt-modified Pd/C in H 2 O/CH 2 Cl 2 can efficiently catalyse the transformation of aromatic ethers, which can be derived from biomass, to cyclohexanone and its derivatives via hydrogenation and hydrolysis processes. The yield of cyclohexanone from anisole can reach 96%, and the yields of cyclohexanone derivatives produced from the aromatic ethers, which can be extracted from plants or derived from lignin, are also satisfactory. Detailed study shows that the Pd, bromide salt and H 2 O/CH 2 Cl 2 work cooperatively to promote the desired reaction and inhibit the side reaction. Thus high yields of desired products can be obtained. This work opens the way for production of ketones from aromatic ethers that can be derived from biomass.

The transformation of triclosan by laccase: Effect of humic acid on the reaction kinetics, products and pathway.

PubMed

Dou, Rong-Ni; Wang, Jing-Hao; Chen, Yuan-Cai; Hu, Yong-You

2018-03-01

This study systematically explored the effect of humic acid (HA) (as model of natural organic matter) on the kinetics, products and transformation pathway of triclosan (TCS) by laccase-catalyzed oxidation. It was found that TCS could be effectively transformed by laccase-catalysis, with the apparent second-order rate constant being 0.056 U -1 mL min -1 . HA inhibited the removal rate of TCS. HA-induced inhibition was negatively correlated with HA concentration in the range of 0-10 mg L -1 and pH-dependent from 3.5 to 9.5. FT-IR and 13 C NMR spectra showed a decrease of aromatic hydroxyl (phenolic) groups and an increase of aromatic ether groups, indicating the cross-linking of HA via C-O-C and C-N-C bonds during enzyme-catalyzed oxidation. Ten principle oxidative products, including two quinone-like products (2-chlorohydroquinone, 2-chloro-5-(2,4-dichlodichlorophenoxy)-(1,4)benzoquinone), one chlorinated phenol (2,4-dichlorophenol (2,4-DCP)), three dimers, two trimmers and two tetramers, were detected by gas chromatograghy/mass spectrometry (GC-MS) and high performance liquid chromatography/quadrupole time-of-flight/mass spectrometry (HPLC/Q-TOF/MS). The presence of HA induced significantly lesser generation of self-polymers and enhanced cross-coupling between HA and self-polymers via C-O-C, C-N-C and C-C coupling pathways. A plausible transformation pathway was proposed as follows: TCS was initially oxidized to form reactive phenoxyl radicals, which self-coupled to each other subsequently by C-C and C-O pathway, yielding self-polymers. In addition, the scission of ether bond was also observed. The presence of HA can promote scission of ether bond and further oxidation of phenoxyl radicals, forming hydroxylated or quinone-like TCS. This study shed light on the behavior of TCS in natural environment and engineered processes, as well provided a perspective for the water/wastewater treatment using enzyme-catalyzed oxidation techniques. Copyright © 2017 Elsevier Ltd. All rights reserved.

Water-soluble ferrocene complexes (WFCs) functionalized silica nanospheres for WFC delivery in HepG2 tumor therapy.

PubMed

Yan, Saisai; Hu, Fan; Hong, Xia; Shuai, Qi

2018-09-01

Silica-encapsulated nanospheres of water-soluble ferrocene complexes WFCs@SiO 2 and WFCs@SiO 2 @glutaraldehyde (GA) were first synthesized by a facile inverse-microemulsion method. The surface functional groups, particle size, and morphologies of nanospheres were characterized by IR spectra, UV-vis absorption spectra, dynamic light scattering (DLS) and SEM images. Single-crystal X-ray diffraction was used to confirm the molecular structure of free ferrocenyl-pyrazol ligand (L) and three WFCs, namely, [Ni(C 22 H 14 F 6 FeN 4 O 4 )(H 2 O) 4 ] (5a), [Mg(C 22 H 14 F 6 FeN 4 O 4 )(H 2 O) 4 ]·3H 2 O (5b), and [Ba(C 22 H 14 F 6 FeN 4 O 4 )(H 2 O) 3 ] (5c). The electrochemical properties of 5a-5c were explored by cyclic voltammetry. The WFCs-loading capacities of 5a-5c in WFCs@SiO 2 were found to be 38.4, 38.2, and 38.1 μg/mg, respectively. Cell studies under two drug delivery modes (free diffusion and endocytosis) were carried out by MTT cell-survival assays and morphological observation of HepG2 cells. It's interesting that the cytotoxicity of WFCs against HepG2 was increased by applying silica nanocarriers. Compared to WFCs@SiO 2 , the modification of GA on the spherical surface provided not only the better water-dispersity but also additional functional groups for further modification of other pharmacophores. The novel nanocarrier system for WFC delivery present a novel concept-of-proof method to protect varieties of affordable metal-based anticancer agents in physiological conditions and provided experimental basis for future studies focusing on drug delivery of other WFCs. Copyright © 2018 Elsevier B.V. All rights reserved.

Physicochemical stability and inactivation of human and simian rotaviruses

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

Meng, Z.D.; Birch, C.; Heath, R.

1987-04-01

The effects of various physical and chemical treatments on the stability of a human serotype 1 rotavirus and simian agent 11 (SA11) were compared by using a fluorescence focus assay. The infectivity of both strains was retained after storage at room temperature for 14 days, 4 degree C for 22 days, and -20 degree C for 32 days; lyophilization; and treatment at pH 3 to 11. Both viruses were inactivated at pH 12, as was the human virus at pH 2, although this pH resulted in only partial inactivation of SA11. The human virus also appeared to be more sensitivemore » than SA11 to the action of ether and chloroform. The infectivity of both viruses was lost after UV irradiation for 15 min and after treatment with 8% formaldehyde for 5 min, 70% (vol/vol) ethanol for 30 min, and 2% lysol, 2% phenol, and 1% H/sub 2/O/sub 2/ for 1 h each.« less

Ionizing radiation-induced destruction of benzene and dienes in aqueous media.

PubMed

Al-Sheikhly, Mohamad; Poster, Dianne L; An, Jung-Chul; Neta, Pedatsur; Silverman, Joseph; Huie, Robert E

2006-05-01

Pulse radiolysis with spectrophotometric and conductometric detection was utilized to study the formation and reactions of radicals from benzene and dienes in aqueous solutions. The benzene OH adduct, *C6H6OH, reacts with O2 (k = 3 x 10(8) L mol(-1) s(-1)) in a reversible reaction. The peroxyl radical, HOC6H6O2*, undergoes O2*- elimination, bimolecular decay, and reaction with benzene to initiate a chain reaction, depending on the dose rate, benzene concentration, and pH. The occurrence of the chain reaction is demonstrated in low-dose-rate gamma radiolysis experiments where the consumption of O2 was monitored. 1,4-Cyclohexadiene, 1,4-hexadiene, and 1,4-pentadiene form OH-adducts and undergo H-abstraction by O*- radicals. The OH-adducts react with O2 to form peroxyl radicals. These peroxyl radicals, however, do not undergo unimolecular O2*- elimination but rather decay by second-order processes, which lead to subsequent steps of O2*- elimination.

Processings of Conference on Dynamics of Precision Gun Weapons (1st), held at Rock Island, Illinois, on January 26-27, 1977

DTIC Science & Technology

1977-02-18

Ji+ k’ W", 0 where T DIO 0 T 1tor _2 f \\ - + _3 Pz~ -dt - t f [2\\1O m+l/ ab + b Jb d and (26) T 3 (T z) i )F k j [2 (f 0i + x ~ A 1 Jd t ,., The terms...I 6b7 + A2 (0+)6 ( bjb 3 ) ItO )T Df + x AT 6b dt The end and jump conditions for A and A are 1 2 1 - A(tl 0 -) = 0 2 [Xi(tlO-) fi(tlO-)] = 0i=l...00 0 c’) 0 C’) 00 c’) 9: IAH HI ON co 0’ c a, - H 0 0 0 0 0H C1 H 0 0 000 0 Z F4 HH o 0 U C4 0 0 ’z AH H I U) -E- z 0 H ~P4 E-4 0 H H C4 C4 14 C4 C w

Constraining the Molecular Complexity in the Interstellar Medium—The Formation of Ethyl Methyl Ether (CH3OCH2CH3) in Star-forming Regions

NASA Astrophysics Data System (ADS)

Bergantini, Alexandre; Frigge, Robert; Kaiser, Ralf I.

2018-05-01

We report the first confirmed synthesis of ethyl methyl ether (EME, CH3CH2OCH3) within astrophysical model ices containing water (H2O) and methane (CH4) exposed to ionizing radiation at ultra-low temperatures of 5 K. EME (also known as methoxyethane), was recently observed toward Orion KL and currently is the largest confirmed oxygen-bearing molecule found in the interstellar medium. Exploiting isomer-selective photoionization (PI) of the subliming molecules in the temperature-programmed desorption phase at 10.49, 9.92, and 9.70 eV, coupled with reflectron time-of-flight mass spectrometry and isotopic substitution experiments (H2 18O–CH4), the detection of fragment ions of EME at m/z = 45 (C2H5O+) and m/z = 59 (C3H7O+), and probing the proton transfer in subliming ethanol–EME complexes via m/z = 61 (C3H9O+), the present study reveals that EME can be formed from suprathermal reactions initiated by cosmic rays and secondary electrons generated within astrophysical ices. The detection of EME in our experiments represents a significant advance in the understanding of formation pathways of complex organic molecules present in hot cores and helps to constrain astrochemical models on the formation of such species within molecular clouds.

Synthesis and crystal structures of inclusion compounds of 2,2'-dithiosalicylic acid and triethylamine/tripropylamine

NASA Astrophysics Data System (ADS)

Yang, Y. X.; Li, H. Y.; Wu, J. F.

2015-12-01

Herein we reported two new inclusion compounds of 2,2'-dithiosalicylic acid (C14H10O4S2, DTSA) and triethylamine and tripropylamine, [C14H8O4S 2 2- · [N+(C2H5)3]2 · H2O] (1) and [C14H10O4S2 · C14H8O4S 2 2- · [N+(C3H7)3]2] (2). Compound 1: triclinic P overline 1, a = 8.2159(2), b = 12.5724(3), c = 14.9203(3) Å, α = 97.0390(10), β = 101.4310(10)°, γ = 101.3370(10)°, V = 1460.06(6) Å3, Z = 2, R 1 = 0.0526, wR 2 = 0.1495; Compound 2: monoclinic P21/ c, a = 20.5178(13), b = 15.3623(8), c = 15.5529(9) Å, β = 102.036(3)°, V = 4794.5(5) Å3, Z = 4, R 1 = 0.0533, wR 2 = 0.1252. In these two crystal structures, DTSA utilizes conventional O-H···O hydrogen bonds to link to generate varied host lattices, in which the central N atoms of the guest amine molecules accept the protons of DTSA to form the corresponding cations to act as the couterions to develop the stable crystal structures. Noticeably, except Van der Waals forces usually existing between the host and guest molecules, the central N atoms of the guests of the two compounds can construct strong N-H…O hydrogen bonds with the related host molecules, which further enforce the host-guest interactions to help form the final inclusion compounds.

Design and syntheses of hybrid metal-organic materials based on K3[M(C2O4)3]·3H2O [M(III)=Fe, Al, Cr] metallotectons

NASA Astrophysics Data System (ADS)

Sun, Yayong; Zong, Yingxia; Ma, Haoran; Zhang, Ao; Liu, Kang; Wang, Debao; Wang, Wenqiang; Wang, Lei

2016-05-01

By using K3[M(C2O4)3]·3H2O [M(III)=Fe, Al, Cr] (C2O42-=oxalate) metallotectons as the starting material, we have synthesized eight novel complexes with formulas [{Fe(C2O4)2(H2O)2}2]·(H-L1)2·H2O 1, [Fe(C2O4)Cl2]·(H2-L2)0.5·(L2)0.5·H2O 2, [{Fe(C2O4)1.5Cl2}2]·(H-L3)43, [Fe2(C2O4)Cl8]·(H2-L4)2·2H2O 4, K[Al(C2O4)3]·(H2-L5)·2H2O 5, K[Al(C2O4)3]·(H-L6)2·2H2O 6, K[Cr(C2O4)3]·2H2O 7, Na[Fe(C2O4)3]·(H-L6)2·2H2O 8 (with L1=4-dimethylaminopyridine, L2=2,3,5,6-tetramethylpyrazine, L3=2-aminobenzimidazole, L4=1,4-bis-(1H-imidazol-1-yl)benzene, L5=1,4-bis((2-methylimidazol-1-yl)methyl)benzene, L6=2-methylbenzimidazole). Their structures have been determined by single-crystal X-ray diffraction analyses, elemental analyses, IR spectra and thermogravimetric analyses. Compound 3 is a 2D H-bonded supramolecular architecture. Others are 3D supramolecular structures. Compound 1 shows a [Fe(C2O4)2(H2O)2]- unit and 3D antionic H-bonded framework. Compound 2 features a [Fe(C2O4)Cl2]- anion and 1D iron-oxalate-iron chain. Compound 3 features a [Fe2(C2O4)3Cl4]4- unit. Compound 4 features distinct [Fe2(C2O4)Cl8]4- units, which are mutual linked by water molecules to generated a 2D H-bonded network. Compound 5 features infinite ladder-like chains constructed by [Al(C2O4)3]3- units and K+ cations. The 1D chains are further extended into 3D antionic H-bonded framework through O-H···O H-bonds. Compounds 6-8 show 2D [KAl(C2O4)3]2- layer, [KCr(C2O4)3]2- layer and [NaFe(C2O4)3]2- layer, respectively.

Partial Molar Volumes of 15-Crown-5 Ether in Mixtures of N,N-Dimethylformamide with Water.

PubMed

Tyczyńska, Magdalena; Jóźwiak, Małgorzata

2014-01-01

The density of 15-crown-5 ether (15C5) solutions in the mixtures of N,N -dimethylformamide (DMF) and water (H 2 O) was measured within the temperature range 293.15-308.15 K using an Anton Paar oscillatory U-tube densimeter. The results were used to calculate the apparent molar volumes ( V Φ ) of 15C5 in the mixtures of DMF + H 2 O over the whole concentration range. Using the apparent molar volumes and Redlich and Mayer equation, the standard partial molar volumes of 15-crown-5 were calculated at infinite dilution ([Formula: see text]). The limiting apparent molar expansibilities ( α ) were also calculated. The data are discussed from the point of view of the effect of concentration changes on interactions in solution.

An Interactive Computer Program for the Preliminary Design and Analysis of Marine Reduction Gears.

DTIC Science & Technology

1982-03-01

4 E-4 c 043 04 4 E- PQ = 24 0 0 E- m 2054 4a =44 Env)2 d0 a b43 09 0 4 I6.4 44 = w. 0k2. . U)3c m 00 I= =C * 4 0 . O)U ad i 0 0~P In3 U= 4 40:M = 4 m...pa *Q4 2 c4~ .~ co N ra a9.* o H 00a = = :b4 H~ H U (3 C) U- of *4= t. E- H)40 UUO *n04 043 q N. W E-4 E-4 1.4-0 31 H 000 oi-4. H4 - M0 2I 2 04 E- HU...aO o %-c ’. %D in0 o f 3W -+V E4pa a noM pa pa pCa 0 pa H14 . pa H 1.4 pa ~00 MtH x 4 -4 U 4E4E4 0 E-4 H E ~ CaM N4 -40 0 UE- E.UE- u 0 c E4 0 9 E-4

Crystal chemistry of thorium nitrates and chromates

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

Sigmon, Ginger E.; Burns, Peter C., E-mail: pburns@nd.ed

2010-07-15

The structures and infrared spectra of six novel thorium compounds are reported. Th(NO{sub 3}){sub 2}(OH){sub 2}(H{sub 2}O){sub 2} (1) crystallizes in space group C2/c, a=14.050(1), b=8.992(7), c=5.954(5) A, {beta}=101.014(2){sup o}. K{sub 2}Th(NO{sub 3}){sub 6} (2), P-3, a=13.606(1), c=6.641(6) A. (C{sub 12}H{sub 28}N){sub 2}Th(NO{sub 3}){sub 6} (3), P2{sub 1}/c, a=14.643(4), b=15.772(5), c=22.316(5) A, {beta}=131.01(1){sup o}. KTh(NO{sub 3}){sub 5}(H{sub 2}O){sub 2} (4), P2{sub 1}/c, a=10.070(8), b=12.731(9), c=13.231(8) A, {beta}=128.647(4){sup o}. Th(CrO{sub 4}){sub 2}(H{sub 2}O){sub 2} (5), P2{sub 1}/n, a=12.731(1), b=9.469(8), c=12.972(1) A, {beta}=91.793(2){sup o}. K{sub 2}Th{sub 3}(CrO{sub 4}){sub 7}(H{sub 2}O){sub 10} (6), Ama2, a=19.302(8), b=15.580(6), c=11.318(6) A. The coordination polyhedra about Thmore » in these structures are diverse. Th is coordinated by 9 O atoms in 5 and 6, seven of which are from monodentate (CrO{sub 4}) tetrahedra and two are (H{sub 2}O). The Th in compound 1 is coordinated by ten O atoms, four of which are O atoms of two bidentate (NO{sub 3}) triangles and six of which are (OH) and (H{sub 2}O). In compounds 2, 3 and 4 the Th is coordinate by 12 O atoms. In 2 and 3 there are six bidentate (NO{sub 3}) triangles, and in 4 ten of the O atoms are part of five bidentate (NO{sub 3}) triangles and the others are (H{sub 2}O) groups. The structural units of these compounds consist of a chain of thorium and nitrate polyhedra (1), isolated thorium hexanitrate clusters (2, 3), an isolated thorium pentanitrate dihydrate cluster (4), and a sheet (6) and framework (5) of thorium and chromate polyhedra. These structures illustrate the complexity inherent in the crystal chemistry of Th. - Graphical Abstract: The structures and infrared spectra of four new Th nitrates and two Th chromates are reported. The coordination numbers of the Th cations range from nine to 12 in these compounds. Structural units consist of isolated clusters, chains, sheets and frameworks.« less

Synthesis and Structural Characterization of Magnesium Based Coordination Networks in Different Solvents

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

D Banerjee; J Finkelstein; A Smirnov

2011-12-31

Three magnesium based metal-organic frameworks, Mg{sub 3}(3,5-PDC){sub 3}(DMF){sub 3} {center_dot} DMF [1], Mg(3,5-PDC)(H{sub 2}O) {center_dot} (H{sub 2}O) [3], and Mg{sub 4}(3,5-PDC){sub 4}(DMF){sub 2}(H{sub 2}O){sub 2} {center_dot} 2DMF {center_dot} 4.5H{sub 2}O [4], and a 2-D coordination polymer, [Mg(3,5-PDC)(H{sub 2}O){sub 2}] [2] [PDC = pyridinedicarboxylate], were synthesized using a combination of DMF, methanol, ethanol, and water. Compound 1 [space group P2{sub 1}/n, a = 12.3475(5) {angstrom}, b = 11.1929(5) {angstrom}, c = 28.6734(12) {angstrom}, {beta} = 98.8160(10){sup o}, V = 3916.0(3) {angstrom}{sup 3}] consists of a combination of isolated and corner-sharing magnesium octahedra connected by the organic linkers to form a 3-Dmore » network with a 12.2 {angstrom} x 4.6 {angstrom} 1-D channel. The channel contains coordinated and free DMF molecules. In compound 2 [space group C2/c, a = 9.964(5) {angstrom}, b = 12.0694(6) {angstrom}, c = 7.2763(4) {angstrom}, {beta} = 106.4970(6){sup o}, V = 836.70(6) {angstrom}{sup 3}], PDC connects isolated seven coordinated magnesium polyhedra into a layered structure. Compound 3 [space group P6{sub 1}22, a = 11.479(1) {angstrom}, c = 14.735(3) {angstrom}, V = 1681.7(4) {angstrom}{sup 3}] (previously reported) contains isolated magnesium octahedra connected by the organic linker with each other forming a 3D network. Compound 4 [space group P2{sub 1}/c, a = 13.7442(14) {angstrom}, b = 14.2887(15) {angstrom}, c = 14.1178(14) {angstrom}, {beta} = 104.912(2){sup o}, V = 2679.2(5) {angstrom}{sup 3}] also exhibits a 3D network based on isolated magnesium octahedra with square cavities containing both disordered DMF and water molecules. The structural topologies originate due to the variable coordination ability of solvent molecules with the metal center. Water molecules coordinate with the magnesium metal centers preferably over other polar solvents (DMF, methanol, ethanol) used to synthesize the coordination networks. Despite testing multiple desolvation routes, we were unable to measure BET surface areas greater than 51.9 m{sup 2}/g for compound 1.« less

Synthesis and Structural Characterization of Magnesium Based Coordination Networks in Different Solvents

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

Banerjee, Debasis; Finkelstein, Jeffrey; Smirnov, A.

2015-10-15

Three magnesium based metal-organic frameworks, Mg{sub 3}(3,5-PDC){sub 3}(DMF){sub 3} {center_dot} DMF [1], Mg(3,5-PDC)(H{sub 2}O) {center_dot} (H{sub 2}O) [3], and Mg4(3,5-PDC)4(DMF){sub 2}(H{sub 2}O){sub 2} {center_dot} 2DMF {center_dot} 4.5H{sub 2}O [4], and a 2-D coordination polymer, [Mg(3,5-PDC)(H{sub 2}O){sub 2}] [2] [PDC = pyridinedicarboxylate], were synthesized using a combination of DMF, methanol, ethanol, and water. Compound 1 [space group P2{sub 1}/n, a = 12.3475(5) {angstrom}, b = 11.1929(5) {angstrom}, c = 28.6734(12) {angstrom}, {beta} = 98.8160(10){sup o}, V = 3916.0(3) {angstrom}{sup 3}] consists of a combination of isolated and corner-sharing magnesium octahedra connected by the organic linkers to form a 3-D network withmore » a 12.2 {angstrom} x 4.6 {angstrom} 1-D channel. The channel contains coordinated and free DMF molecules. In compound 2 [space group C2/c, a = 9.964(5) {angstrom}, b = 12.0694(6) {angstrom}, c = 7.2763(4) {angstrom}, {beta} = 106.4970(6){sup o}, V = 836.70(6) {angstrom}{sup 3}], PDC connects isolated seven coordinated magnesium polyhedra into a layered structure. Compound 3 [space group P6{sub 1}22, a = 11.479(1) {angstrom}, c = 14.735(3) {angstrom}, V = 1681.7(4) {angstrom}{sup 3}] (previously reported) contains isolated magnesium octahedra connected by the organic linker with each other forming a 3D network. Compound 4 [space group P2{sub 1}/c, a = 13.7442(14) {angstrom}, b = 14.2887(15) {angstrom}, c = 14.1178(14) {angstrom}, {beta} = 104.912(2){sup o}, V = 2679.2(5) {angstrom}{sup 3}] also exhibits a 3D network based on isolated magnesium octahedra with square cavities containing both disordered DMF and water molecules. The structural topologies originate due to the variable coordination ability of solvent molecules with the metal center. Water molecules coordinate with the magnesium metal centers preferably over other polar solvents (DMF, methanol, ethanol) used to synthesize the coordination networks. Despite testing multiple desolvation routes, we were unable to measure BET surface areas greater than 51.9 m{sup 2}/g for compound 1.« less

Framework fluxionality of organometallic oxides: synthesis, crystal structure, EXAFS, and DFT studies on [[Ru(eta6-arene)]4Mo4O16] complexes.

PubMed

Laurencin, Danielle; Garcia Fidalgo, Eva; Villanneau, Richard; Villain, Françoise; Herson, Patrick; Pacifico, Jessica; Stoeckli-Evans, Helen; Bénard, Marc; Rohmer, Marie-Madeleine; Süss-Fink, Georg; Proust, Anna

2004-01-05

Reactions of the molybdates Na(2)MoO4.2 H2O and (nBu(4)N)2[Mo2O7] with [[Ru(arene)Cl(2)](2)] (arene=C(6)H5CH3, 1,3,5-C6H3(CH3)(3), 1,2,4,5-C6H2(CH3)4) in water or organic solvents led to formation of the triple-cubane organometallic oxides [[Ru(eta(6)-arene)](4)Mo4O16], whose crystal and molecular structures were determined. Refluxing triple cubane [[Ru(eta(6)-C6H5CH3)](4)Mo4O16] in methanol caused partial isomerization to the windmill form. The two isomers of [[Ru(eta(6)-C6H5CH3)](4)Mo4O16] were characterized by Raman and Mo K-edge X-ray absorption spectroscopy (XAS), both in the solid-state and in solution. This triple-cubane isomer was also used as a spectroscopic model to account for isomerization of the p-cymene windmill [[Ru(eta(6)-1,4-CH3C6H4CH(CH3)2)](4)Mo4O16] in solution. Using both Raman and XAS techniques, we were then able to determine the ratio between the windmill and triple-cubane isomers in dichloromethane and in chloroform. Density functional calculations on [[Ru(eta(6)-arene)](4)Mo4O16] (arene=C6H6, C6H5CH3, 1,3,5-C6H3(CH3)3, 1,4-CH3C6H4CH(CH3)2, C6(CH3)6) suggest that the windmill form is intrinsically more stable, provided the complexes are assumed to be isolated. Intramolecular electrostatic interactions and steric bulk induced by substituted arenes were found to modulate but not to reverse the energy difference between the isomers. The stability of the triple-cubane isomers should therefore be accounted for by effects of the surroundings that induce a shift in the energy balance between both forms.

Coupled antiferromagnetic spin- 1 2 chains in green dioptase Cu 6 [ Si 6 O 18 ] · 6 H 2 O

DOE PAGES

Podlesnyak, Andrey A; Larry M. Anovitz; Kolesnikov, Alexander I; ...

2016-02-01

Inmore » this paper, we report inelastic neutron scattering measurements of the magnetic excitations of green dioptase Cu 6[Si 6O 18]∙6H 2O. The observed spectrum contains two magnetic modes and a prominent spin gap that is consistent with the ordered ground state of Cu moments coupled antiferromagnetically in spiral chains along the c axis and ferromagnetically in ab planes on the hexagonal cell. The data are in excellent agreement with a spin- 1 2 Hamiltonian that includes antiferromagnetic nearest-neighbor intrachain coupling J c=10.6(1) meV, ferromagnetic interchain coupling J ab=₋1.2 (1) meV, and exchange anisotropy ΔJ c=0.14(1) meV. We calculated the sublattice magnetization to be strongly reduced, ~0.39μ B. This appears compatible with a reduced Néel temperature, T N=14.5K

River infiltration to a subtropical alluvial aquifer inferred using multiple environmental tracers

NASA Astrophysics Data System (ADS)

Lamontagne, S.; Taylor, A. R.; Batlle-Aguilar, J.; Suckow, A.; Cook, P. G.; Smith, S. D.; Morgenstern, U.; Stewart, M. K.

2015-06-01

Chloride (Cl-), stable isotope ratios of water (δ18O and δ2H), sulfur hexafluoride (SF6), tritium (3H), carbon-14 (14C), noble gases (4He, Ne, and Ar), and hydrometry were used to characterize groundwater-surface water interactions, in particular infiltration rates, for the Lower Namoi River (New South Wales, Australia). The study period (four sampling campaigns between November 2009 and November 2011) represented the end of a decade-long drought followed by several high-flow events. The hydrometry showed that the river was generally losing to the alluvium, except when storm-derived floodwaves in the river channel generated bank recharge—discharge cycles. Using 3H/14C-derived estimates of groundwater mean residence time along the transect, infiltration rates ranged from 0.6 to 5 m yr-1. However, when using the peak transition age (a more realistic estimate of travel time in highly dispersive environments), the range in infiltration rate was larger (4-270 m yr-1). Both river water (highest δ2H, δ18O, SF6, 3H, and 14C) and an older groundwater source (lowest δ2H, δ18O, SF6, 3H, 14C, and highest 4He) were found in the riparian zone. This old groundwater end-member may represent leakage from an underlying confined aquifer (Great Artesian Basin). Environmental tracers may be used to estimate infiltration rates in this riparian environment but the presence of multiple sources of water and a high dispersion induced by frequent variations in the water table complicates their interpretation.

Shear rheology and in-vitro release kinetic study of apigenin from lyotropic liquid crystal.

PubMed

Fan, Jun; Liu, Feng; Wang, Zhongni

2016-01-30

Apigenin is a flavonoid compound with diverse pharmacological functions which could develop health benefit products, but its formulation is hampered by its poor water solubility and bioavailability. In this paper, in order to overcome these difficulties, apigenin was encapsulated in LLC formed by polyoxyethylene-10-oleyl ether (Brij 97) and sodium deoxycholate (NaDC) mixtures. The hexagonal liquid crystalline phase (H) and the cubic liquid crystalline phase (C) were found in this system. The shear rheology was used to study the structure change with temperature. It was shown that C3 (Brij 97-NaDC/IPM-PEG400/H2O=36:9:55) was C at low temperature. But above 35.6°C, the matrix of C3 completely transformed to polymer solution. The matrix of H3 was H (Brij 97-NaDC:IPM-PEG 400:H2O=50:9:41) below 50°C, but the structural strength change was obvious. Vitro release experiment was used to study drug release kinetics. It was indicated that apigenin encapsulated in LLC conformed to the concentration diffusion model, and cumulative percentage of apigenin released from C3 and H3 had corresponding relationship with the shear rheology at different temperatures. Copyright © 2015. Published by Elsevier B.V.

Effect of H2 and redox condition on biotic and abiotic MTBE transformation

USGS Publications Warehouse

Bradley, P.M.; Chapelle, F.H.; Landmeyer, J.E.

2006-01-01

Laboratory studies conducted with surface water sediment from a methyl tert-butyl ether (MTBE)-contaminated site in South Carolina demonstrated that, under methanogenic conditions, [U-14C] MTBE was transformed to 14C tert-butyl alcohol (TBA) with no measurable production of 14CO2. Production of TBA was not attributed to the activity of methanogenic microorganisms, however, because comparable transformation of [U-14C] MTBE to 14C-TBA also was observed in heat-sterilized controls with dissolved H2 concentrations > 5 nM. The results suggest that the transformation of MTBE to TBA may be an abiotic process that is driven by biologically produced H2 under in situ conditions. In contrast, mineralization of [U-14C] MTBE to 14CO2 was completely inhibited by heat sterilization and only observed in treatments characterized by dissolved H2 concentrations < 2 nM. These results suggest that the pathway of MTBE transformation is influenced by in situ H2 concentrations and that in situ H2 concentrations may be an useful indicator of MTBE transformation pathways in ground water systems.

Conformations and Barriers to Methyl Group Internal Rotation in Two Asymmetric Ethers: Propyl Methyl Ether and Butyl Methyl Ether

NASA Astrophysics Data System (ADS)

Long, B. E.; Dechirico, F.; Cooke, S. A.

2012-06-01

The conformational preferences of the O-C-C-C unit are important in many biological systems with the unit generally preferring a gauche configuration compared to an anti configuration. Butyl methyl ether and propyl methyl ether provide very simple systems for this phenomenom to manifest. Pure rotational spectra of the title molecules have been recorded using chirped pulse Fourier transform microwave spectroscopy (CP-FTMW). In the case of butyl methyl ether, only one conformer has been observed. This conformer has torsional angles of COCC = 180°, OCCC = 62° and CCCC = 180° (anti-gauche-anti) and rotational constants of A = 10259.4591(33) MHz, B = 1445.6470(13) MHz, and C = 1356.2944(14) MHz. The rotational spectrum was doubled and has been analyzed to produce an effective barrier to methyl group internal rotation of 780(35) cm-1. A prior rotational spectroscopic study on propyl methyl ether had focused only on the high energy anti-anti conformer. We have analyzed spectra from the lowest energy anti-gauche conformer and the spectroscopic constants will be presented. A summary of the differences in conformational energies and methyl group internal rotation barriers for the class of aliphatic asymmetric ethers will be presented. K. N. Houk, J. E. Eksterowicz, Y.-D. Wu, C. D. Fuglesang, D. B. Mitchell. J. Am. Chem. Soc. 115 (4170), 1993. Hiroshi Kato, Jun Nakagawa, Michiro Hayashi. J. Mol. Spectrosc. 80 (272), 1980.

C-H functionalization of phenols using combined ruthenium and photoredox catalysis: in situ generation of the oxidant.

PubMed

Fabry, David C; Ronge, Meria A; Zoller, Jochen; Rueping, Magnus

2015-02-23

A combination of ruthenium and photoredox catalysis allowed the ortho olefination of phenols. Using visible light, the direct C-H functionalization of o-(2-pyridyl)phenols occurred, and diverse phenol ethers were obtained in good yields. The regeneration of the ruthenium catalyst was accomplished by a photoredox-catalyzed oxidative process. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and Properties of Poly(ether sulfone)s with Clustered Sulfonic Groups for PEMFC Applications under Various Relative Humidity.

PubMed

Lee, Shih-Wei; Chen, Jyh-Chien; Wu, Jin-An; Chen, Kuei-Hsien

2017-03-22

Novel sulfonated poly(ether sulfone) copolymers (S4PH-x-PSs) based on a new aromatic diol containing four phenyl substituents at the 2, 2', 6, and 6' positions of 4,4'-diphenyl ether were synthesized. Sulfonation was found to occur exclusively on the 4 position of phenyl substituents by NMR spectroscopy. The ion exchange capacity (IEC) values can be controlled by adjusting the mole percent (x in S4PH-x-PS) of the new diol. The fully hydrated sulfonated poly(ether sulfone) copolymers had good proton conductivity in the range 0.004-0.110 S/cm at room temperature. The surface morphology of S4PH-x-PSs and Nafion 212 was investigated by atomic force microscopy (tapping-mode) and related to the percolation limit and proton conductivity. Single H 2 /O 2 fuel cell based on S4PH-40-PS loaded with 0.25 mg/cm 2 catalyst (Pt/C) exhibited a peak power density of 462.6 mW/cm 2 , which was close to that of Nafion 212 (533.5 mW/cm 2 ) at 80 °C with 80% RH. Furthermore, fuel cell performance of S4PH-35-PS with various relative humidity was investigated. It was confirmed from polarization curves that the fuel cell performance of S4PH-35-PS was not as high as that of Nafion 212 under fully hydrated state due to higher interfacial resistance between S4PH-35-PS and electrodes. While under low relative humidity (53% RH) at 80 °C, fuel cells based on S4PH-35-PS showed higher peak power density (234.9 mW/cm 2 ) than that (214.0 mW/cm 2 ) of Nafion 212.

Selective Cleavage of the Aryl Ether Bonds in Lignin for Depolymerization by Acidic Lithium Bromide Molten Salt Hydrate under Mild Conditions.

PubMed

Yang, Xiaohui; Li, Ning; Lin, Xuliang; Pan, Xuejun; Zhou, Yonghong

2016-11-09

The present study demonstrates that the concentrated lithium bromide (LiBr) solution with acid as catalyst was able to selectively cleave the β-O-4 aryl ether bond and lead to lignin depolymerization under mild conditions (e.g., in 60% LiBr with 0.3 M HCl at 110 °C for 2 h). Four industrial lignins from different pulping and biorefining processes, including softwood kraft lignin (SKL), hardwood kraft lignin (HKL), softwood ethanol organosolv lignin (EOL), and acid corncob lignin (ACL), were treated in the LiBr solution. The molecular weight, functional group, and interunit linkages of the lignins were characterized using GPC, FTIR, and NMR. The results indicated that the β-O-4 aryl ether bonds of the lignins were selectively cleaved, and both LiBr and HCl played crucial roles in catalyzing the cleavage of the ether bonds.

Carbon-carbon bond cleavage of 1,2-hydroxy ethers b7 vanadium(V) dipicolinate complexes

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

Hanson, Susan K; Gordon, John C; Thorn, David L

2009-01-01

The development of alternatives to current petroleum-based fuels and chemicals is becoming increasingly important due to concerns over climate change, growing world energy demand, and energy security issues. Using non-food derived biomass to produce renewable feedstocks for chemicals and fuels is a particularly attractive possibility. However, the majority of biomass is in the form of lignocellulose, which is often not fully utilized due to difficulties associated with breaking down both lignin and cellulose. Recently, a number of methods have been reported to transform cellulose directly into more valuable materials such as glucose, sorbitol, 5-(chloromethyl)furfural, and ethylene glycol. Less progress hasmore » been made with selective transformations of lignin, which is typically treated in paper and forest industries by kraft pulping (sodium hydroxide/sodium sulfide) or incineration. Our group has begun investigating aerobic oxidative C-C bond cleavage catalyzed by dipicolinate vanadium complexes, with the idea that a selective C-C cleavage reaction of this type could be used to produce valuable chemicals or intermediates from cellulose or lignin. Lignin is a randomized polymer containing methoxylated phenoxy propanol units. A number of different linkages occur naturally; one of the most prevalent is the {beta}-O-4 linkage shown in Figure 1, containing a C-C bond with 1,2-hydroxy ether substituents. While the oxidative C-C bond cleavage of 1,2-diols has been reported for a number of metals, including vanadium, iron, manganese, ruthenium, and polyoxometalate complexes, C-C bond cleavage of 1,2-hydroxy ethers is much less common. We report herein vanadium-mediated cleavage of C-C bonds between alcohol and ether functionalities in several lignin model complexes. In order to explore the scope and potential of vanadium complexes to effect oxidative C-C bond cleavage in 1,2-hydroxy ethers, we examined the reactivity of the lignin model complexes pinacol monomethyl ether (A), 2-phenoxyethanol (B), and 1,2-diphenyl-2-methoxyethanol (C) (Figure 1). Reaction of (dipic)V{sup V}(O)O{sup i}Pr (1a) or (dipic)V{sup v}(O)OEt (lb) with A, B, or C in acetonitrile yielded new vanadium(V) complexes where the alcohol-ether ligand was bound in a chelating fashion. From the reaction of 1b with pinacol monomethyl ether (A) in acetonitrile solution, (dipic)V{sup v}(O)(pinOMe) (2) (PinOMe = 2,3-dimethyl-3-methoxy-2-butanoxide) was isolated in 61 % yield. Reaction of 1b with 2-phenoxyethanol (B) in acetonitrile gave the new complex (dipic)V{sup v}(O)(OPE) (3) (OPE = 2-phenoxyethoxide), which was isolated in 76% yield. In a similar fashion, 1a reacted with 1,2-diphenyl-2-methoxyethanol (C) to give (dipic)V(O)(DPME) (4) (DPME = 1,2-diphenyl-2-methoxyethoxide), which was isolated in 39% yield. Complexes 2, 3, and 4 were characterized by {sup 1}H NMR and IR spectroscopy, elemental analysis, and X-ray crystallography. Compared to the previously reported vanadium(V) pinacolate complex (dipic)V(O)(pinOH) the X-ray structure of complex 2 reveals a slightly shorter V = O bond, 1.573(2) {angstrom} vs 1.588(2) {angstrom} for the pinOH structure. Complexes 3 and 4 display similar vanadium oxo bond distances of 1.568(2) {angstrom} and 1.576(2) {angstrom}, respectively. All three complexes show longer bonds to the ether-oxygen trans to the oxo (2.388(2) {angstrom} for 2, 2.547(2) {angstrom} for 3, and 2.438(2) {angstrom} for 4) than to the hydroxy-oxygen in the pinOH structure (2.252(2) {angstrom}).« less

A concise synthesis of a highly substituted 6-(1H-benzimidazol-1-yl)-5-nitrosopyrimidin-2-amine: synthetic sequence and the molecular and supramolecular structures of one product and two intermediates.

PubMed

Cobo, Justo; Vicentes, Daniel E; Rodríguez, Ricaurte; Marchal, Antonio; Glidewell, Christopher

2018-06-01

A concise and efficient synthesis of 6-benzimidazolyl-5-nitrosopyrimidines has been developed using Schiff base-type intermediates derived from N 4 -(2-aminophenyl)-6-methoxy-5-nitrosopyrimidine-2,4-diamine. 6-Methoxy-N 4 -{2-[(4-methylbenzylidene)amino]phenyl}-5-nitrosopyrimidine-2,4-diamine, (I), and N 4 -{2-[(ethoxymethylidene)amino]phenyl}-6-methoxy-5-nitrosopyrimidine-2,4-diamine, (III), both crystallize from dimethyl sulfoxide solution as the 1:1 solvates C 19 H 18 N 6 O 2 ·C 2 H 6 OS, (Ia), and C 14 H 16 N 6 O 3 ·C 2 H 6 OS, (IIIa), respectively. The interatomic distances in these intermediates indicate significant electronic polarization within the substituted pyrimidine system. In each of (Ia) and (IIIa), intermolecular N-H...O hydrogen bonds generate centrosymmetric four-molecule aggregates. Oxidative ring closure of intermediate (I), effected using ammonium hexanitratocerate(IV), produced 4-methoxy-6-[2-(4-methylphenyl-1H-benzimidazol-1-yl]-5-nitrosopyrimidin-2-amine, C 19 H 16 N 6 O 2 , (II) [Cobo et al. (2018). Private communication (CCDC 1830889). CCDC, Cambridge, England], where the extent of electronic polarization is much less than in (Ia) and (IIIa). A combination of N-H...N and C-H...O hydrogen bonds links the molecules of (II) into complex sheets.

Protonation switching to the least-basic heteroatom of carbamate through cationic hydrogen bonding promotes the formation of isocyanate cations.

PubMed

Kurouchi, Hiroaki; Sumita, Akinari; Otani, Yuko; Ohwada, Tomohiko

2014-07-07

We found that phenethylcarbamates that bear ortho-salicylate as an ether group (carbamoyl salicylates) dramatically accelerate OC bond dissociation in strong acid to facilitate generation of isocyanate cation (N-protonated isocyanates), which undergo subsequent intramolecular aromatic electrophilic cyclization to give dihydroisoquinolones. To generate isocyanate cations from carbamates in acidic media as electrophiles for aromatic substitution, protonation at the ether oxygen, the least basic heteroatom, is essential to promote CO bond cleavage. However, the carbonyl oxygen of carbamates, the most basic site, is protonated exclusively in strong acids. We found that the protonation site can be shifted to an alternative basic atom by linking methyl salicylate to the ether oxygen of carbamate. The methyl ester oxygen ortho to the phenolic (ether) oxygen of salicylate is as basic as the carbamate carbonyl oxygen, and we found that monoprotonation at the methyl ester oxygen in strong acid resulted in the formation of an intramolecular cationic hydrogen bond (>CO(+) H⋅⋅⋅O<) with the phenolic ether oxygen. This facilitates OC bond dissociation of phenethylcarbamates, thereby promoting isocyanate cation formation. In contrast, superacid-mediated diprotonation at the methyl ester oxygen of the salicylate and the carbonyl oxygen of the carbamate afforded a rather stable dication, which did not readily undergo CO bond dissociation. This is an unprecedented and unknown case in which the monocation has greater reactivity than the dication. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Pleomorphic copper coordination by Alzheimer's disease amyloid-beta peptide.

PubMed

Drew, Simon C; Noble, Christopher J; Masters, Colin L; Hanson, Graeme R; Barnham, Kevin J

2009-01-28

Numerous conflicting models have been proposed regarding the nature of the Cu(2+) coordination environment of the amyloid beta (Abeta) peptide, the causative agent of Alzheimer's disease. This study used multifrequency CW-EPR spectroscopy to directly resolve the superhyperfine interactions between Cu(2+) and the ligand nuclei of Abeta, thereby avoiding ambiguities associated with introducing point mutations. Using a library of Abeta16 analogues with site-specific (15)N-labeling at Asp1, His6, His13, and His14, numerical simulations of the superhyperfine resonances delineated two independent 3N1O Cu(2+) coordination modes, {N(a)(D1), O, N(epsilon)(H6), N(epsilon)(H13)} (component Ia) and {N(a)(D1), O, N(epsilon)(H6), N(epsilon)(H14)} (component Ib), between pH 6-7. A third coordination mode (component II) was identified at pH 8.0, and simulation of the superhyperfine resonances indicated a 3N1O coordination sphere involving nitrogen ligation by His6, His13, and His14. No differences were observed upon (17)O-labeling of the phenolic oxygen of Tyr10, confirming it is not a key oxygen ligand in the physiological pH range. Hyperfine sublevel correlation (HYSCORE) spectroscopy, in conjunction with site-specific (15)N-labeling, provided additional support for the common role of His6 in components Ia and Ib, and for the assignment of a {O, N(epsilon)(H6), N(epsilon)(H13), N(epsilon)(H14)} coordination sphere to component II. HYSCORE studies of a peptide analogue with selective (13)C-labeling of Asp1 revealed (13)C cross-peaks characteristic of equatorial coordination by the carboxylate oxygen of Asp1 in component Ia/b coordination. The direct resolution of Cu(2+) ligand interactions, together with the key finding that component I is composed of two distinct coordination modes, provides valuable insight into a range of conflicting ligand assignments and highlights the complexity of Cu(2+)/Abeta interactions.

Kinetic Resolution of α-Hydroxy-Substituted Oxime Ethers by Enantioselective Cu-H-Catalyzed Si-O Coupling.

PubMed

Dong, Xichang; Kita, Yuji; Oestreich, Martin

2018-04-12

A catalyst-controlled enantioselective alcohol silylation by Cu-H-catalyzed dehydrogenative Si-O coupling of hydroxy groups α to an oxime ether and simple hydrosilanes is reported. The selectivity factors reached in this kinetic resolution are generally high (s≈50), and these reactions thereby provide reliable access to highly enantioenriched α-hydroxy-substituted oxime ethers. The synthetic usefulness of these compounds is also demonstrated. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

The asymmetric synthesis of terminal aziridines by methylene transfer from sulfonium ylides to imines.

PubMed

Kavanagh, Sarah A; Piccinini, Alessandro; Connon, Stephen J

2013-06-07

A new ylide-based protocol for the asymmetric aziridination of imines via methylene transfer has been developed involving the use of a simple chiral sulfonium salt and an organic strong base. A systematic study identified triisopropylphenyl sulfonylimines as optimal substrates for the process. Unexpectedly, hindered C2-symmetric sulfonyl salts incorporating bulky ethers at C-2 and C-5--which had previously been useful in the corresponding epoxidation chemistry--decomposed in these aziridination reactions via competing elimination pathways. Under optimised conditions it was found that a simple salt derived from (2R,5R)-2,5-diisopropyl thiolane could mediate asymmetric methylene transfer to a range of imines with uniformly excellent yields with 19-30% ee. Since this is a similar level of enantiomeric excess to that obtained using these same salts in epoxidation chemistry, it was concluded that if more bulky sulfonium salts could be devised which were resistant to decomposition under the reaction conditions, that highly enantioselective aziridine formation by methylene transfer would be possible.

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.

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.

New HPLC methods to quantitate terpenoid aldehydes in foliage of cotton (Gossypium)

USDA-ARS?s Scientific Manuscript database

The cotton plant (Gossypium) produces protective terpenoid aldehydes in lysigenous pigment glands. These terpenoids include hemigossypolone, hemigossypolone-6-methyl ether, gossypol, gossypol-6-methyl ether, gossypol-6,6'-dimethyl ether, heliocides H1, H2, H3 and H4, and heliocides B1, B2, B3 and B4...

Synthesis, Structures, and Vibrational Spectroscopy of the Two-Dimensional Iodates Ln(IO) 3 and Ln(IO 3) 3(H 2O) ( Ln-Yb,Lu)

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

Assefa, Zerihun; Ling, Jie; Haire, Richard

2006-01-01

The reaction of Lu3+ or Yb3+ and H5IO6 in aqueous media at 180 C leads to the formation of Yb(IO3)3(H2O) or Lu(IO3)3(H2O), respectively, while the reaction of Yb metal with H5IO6 under similar reaction conditions gives rise to the anhydrous iodate, Yb(IO3)3. Under supercritical conditions Lu3+ reacts with HIO3 and KIO4 to yield the isostructural Lu(IO3)3. The structures have been determined by single-crystal X-ray diffraction. Crystallographic data are (MoKa, {lambda}=0.71073 {angstrom}): Yb(IO3)3, monoclinic, space group P21/n, a=8.6664(9) {angstrom}, b=5.9904(6) {angstrom}, c=14.8826(15) {angstrom}, {beta}=96.931(2){sup o}, V=766.99(13), Z=4, R(F)=4.23% for 114 parameters with 1880 reflections with I>2s(I); Lu(IO3)3, monoclinic, space group P21/n,more » a=8.6410(9), b=5.9961(6), c=14.8782(16) {angstrom}, {beta}=97.028(2){sup o}, V=765.08(14), Z=4, R(F)=2.65% for 119 parameters with 1756 reflections with I>2s(I); Yb(IO3)3(H2O), monoclinic, space group C2/c, a=27.2476(15), b=5.6296(3), c=12.0157(7) {angstrom}, {beta}=98.636(1){sup o}, V=1822.2(2), Z=8, R(F)=1.51% for 128 parameters with 2250 reflections with I>2s(I); Lu(IO3)3(H2O), monoclinic, space group C2/c, a=27.258(4), b=5.6251(7), c=12.0006(16) {angstrom}, {beta}=98.704(2){sup o}, V=1818.8(4), Z=8, R(F)=1.98% for 128 parameters with 2242 reflections with I>2s(I). The f elements in all of the compounds are found in seven-coordinate environments and bridged with monodentate, bidentate, or tridentate iodate anions. Both Lu(IO3)3(H2O) and Yb(IO3)3(H2O) display distinctively different vibrational profiles from their respective anhydrous analogs. Hence, the Raman profile can be used as a complementary diagnostic tool to discern the different structural motifs of the compounds.« less

NCI calculations for understanding a physical phase transition in (C6H14N2)[Mn(H2O)6](SeO4)2

NASA Astrophysics Data System (ADS)

Naïli, Houcine; François, Michel; Norquist, Alexander J.; Rekik, Walid

2017-12-01

An organically templated manganese selenate, (C6H14N2)[Mn(H2O)6](SeO4)2, has been synthesized by slow evaporation and crystallographically characterized. The title compound crystallizes at room temperature in the monoclinic centrosymmetric space group P21/n, with the following unit cell parameters: a = 7.2373(4) Å; b = 12.5600(7) Å; c = 10.1945(7) Å; β = 91.155(4)°, V = 926.50(10) Å3and Z = 2. Its crystal structure is built of manganese(II) cations coordinated by six water molecules in octahedral geometry, disordered dabcodiium cations and selenate anions, resulting in an extensive hydrogen-bonding network. Differential scanning calorimetry (DSC) measurement indicated that the precursor undergoes a reversible phase transition at about 216 and 218 K during the cooling and heating processes respectively. Below this temperature the title compound is noncentrosymmetric with space group P21 and lattice parameters a = 7.2033(8) Å; b = 12.4981(13) Å; c = 10.0888(11) Å; β = 91.281(2)°, V = 908.04(17) Å3 and Z = 2. The disorder-order transformation of the C atoms of (C6H14N2)2+ cation may drive the structural phase transition. The low temperature phase obtained by breaking symmetry presents a fully ordered structure. The noncovalent interaction (NCI) method was used not only to locate, quantify, and visualize intermolecular interactions in the high and low temperature phases but also to confirm the phase transition detected by DSC measurement. The thermal decomposition of this new compound proceeds through four stages giving rise to the manganese oxide as final product at 850 °C.

A chalcone showing positional disorder, two related diarylcyclohexenones showing enantiomeric disorder and a related hydroxyterphenyl, all derived from simple carbonyl precursors.

PubMed

Salian, Vinutha V; Narayana, Badiadka; Yathirajan, Hemmige S; Akkurt, Mehmet; Çelik, Ömer; Ersanlı, Cem Cüneyt; Glidewell, Christopher

2015-07-01

Four compounds are reported, all of which lie along a versatile reaction pathway which leads from simple carbonyl compounds to terphenyls. (2E)-1-(2,4-Dichlorophenyl)-3- [4-(prop-1-en-2-yl)phenyl]prop-2-en-1-one, C18H14Cl2O, (I), prepared from 4-(prop-1-en-2-yl)benzaldehyde and 2,4-dichloroacetophenone, exhibits disorder over two sets of atomic sites having occupancies of 0.664 (6) and 0.336 (6). The related chalcone (2E)-3-(4-chlorophenyl)-1-(4-fluorophenyl)prop-2-en-1-one reacts with acetone to produce (5RS)-3-(4-chlorophenyl)-5-[4-(propan-2-yl)phenyl]cyclohex-2-en-1-one, C21H21ClO, (II), which exhibits enantiomeric disorder with occupancies at the reference site of 0.662 (4) and 0.338 (4) for the (5R) and (5S) forms; the same chalcone reacts with methyl 3-oxobutanoate to give methyl (1RS,6SR)-4-(4-chlorophenyl)-6-[4-(propan-2-yl)phenyl]-2-oxocyclohex-3-ene-1-carboxylate, C23H23ClO3, (III), where the reference site contains both (1R,6S) and (1S,6R) forms with occupancies of 0.923 (3) and 0.077 (3), respectively. Oxidation, using 2,3-dichloro-5,6-dicyano-1,4-benzoquinone, of ethyl (1RS,6SR)-6-(4-bromophenyl)-4-(4-fluorophenyl)-2-oxocyclohex-3-ene-1-carboxylate, prepared in a similar manner to (II) and (III), produces ethyl 4''-bromo-4-fluoro-5'-hydroxy-1,1':3',1''-terphenyl-4'-carboxylate, C21H16BrFO3, (IV), which crystallizes with Z' = 2 in the space group P-1. There are no significant intermolecular interactions in the structures of compounds (I) and (II), but for the major disorder component of compound (III), the molecules are linked into sheets by a combination of C-H...O and C-H...π(arene) hydrogen bonds. The two independent molecules of compound (IV) form two different centrosymmetric dimers, one built from inversion-related pairs of C-H...O hydrogen bonds and the other from inversion-related pairs of C-H...π(arene) hydrogen bonds. Comparisons are made with related compounds.

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.

Synthesis and characterization of two novel inorganic/organic hybrid materials based on polyoxomolybdate clusters: (C5H5N5)2(C5H6N5)4[(HAsO4)2Mo6O18]·11H2O and Na2(Himi)3[SeMo6O21(CH3COO)3]·6H2O

NASA Astrophysics Data System (ADS)

Ayed, Meriem; Mestiri, Imen; Ayed, Brahim; Haddad, Amor

2017-01-01

Two new organic-inorganic hybrid compound, (C5H5N5)2(C5H6N5)4[(HAsO4)2Mo6O18]·11H2O (I) and Na2(Himi)3[SeMo6O21(CH3COO)3]·6H2O (II) were synthesized and structurally characterized by scanning electron microscopy (SEM), elemental analyses, FTIR, UV spectroscopy, thermal stability analysis, XRD and single crystal X-ray diffraction. Crystal data: (I) triclinic system, space group P-1, a = 11,217 (9) Å, b = 11,637 (8) Å, c = 14,919 (8) Å, α = 70,90 (5)°, β = 70,83 (2)°, γ = 62,00(1)° and Z = 1; (II) triclinic system, space group P-1, a = 10.6740(1) Å, b = 10.6740(1) Å, c = 20.0570(1) Å, α = 76.285(1)°, β = 82.198(2)°, γ = 87.075(1)°, Z = 1. The crystal structure of (I) can be described by infinite polyanions [(HAsO4)2Mo6O18]4- organized with water molecules in layers parallel to the c-direction; adjacent layers are further joined up by hydrogen bonding interactions with organic groups which were associated in chains spreading along the b-direction. The structure of (II) consists of functionalized selenomolybdate clusters [SeMo6O21(CH3COO)3]5-, protonated imidazole cations, sodium ions and lattice water molecules, which are held together to generate a three-dimensional supramolecular network via hydrogen-bonding interaction. Furthermore, the electrochemical properties of these compounds have been studied.

The hydrolysis of geminal ethers: a kinetic appraisal of orthoesters and ketals.

PubMed

Repetto, Sonia L; Costello, James F; Butts, Craig P; Lam, Joseph K W; Ratcliffe, Norman M

2016-01-01

A novel approach to protecting jet fuel against the effects of water contamination is predicated upon the coupling of the rapid hydrolysis reactions of lipophilic cyclic geminal ethers, with the concomitant production of a hydrophilic acyclic hydroxyester with de-icing properties (Fuel Dehydrating Icing Inhibitors - FDII). To this end, a kinetic appraisal of the hydrolysis reactions of representative geminal ethers was undertaken using a convenient surrogate for the fuel-water interface (D2O/CD3CN 1:4). We present here a library of acyclic and five/six-membered cyclic geminal ethers arranged according to their hydroxonium catalytic coefficients for hydrolysis, providing for the first time a framework for the development of FDII. A combination of (1)H NMR, labelling and computational studies was used to assess the effects that may govern the observed relative rates of hydrolyses.

Selective Ether/Ester C–O Cleavage of an Acetylated Lignin Model via Tandem Catalysis

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

Lohr, Tracy L.; Li, Zhi; Marks, Tobin J.

2015-11-06

Lignin, a heterogeneous phenolic polymer which constitutes roughly 15 to 20 wt % of lignocellulosic biomass (cellulose, hemicellose, and lignin), represents one of the few renewable sources of aromatic monomers.(1) Current lignin depolymerization methodologies, including base-catalyzed,(2) acid-catalyzed,(3) metal-catalyzed,(4) ionic liquid (IL)-assisted,(5) and supercritical-fluid-assisted(2b, 6) approaches, typically afford low yields (~10–20% or less) of low molecular weight aromatics under relatively harsh reaction conditions (>300 °C).(7) Recent advances include using oxidized lignin and lignin models,(8) where oxidation of the Cα alcohol facilitates depolymerizaton, with aromatic monomer yields reaching up to 52% for aspen “hardwood” lignin.(9) The most common structural lignin motifs containmore » a β-O-4 aryl-ether linkage,(10) a primary alcohol in the γ skeletal position, and a secondary alcohol in the α position (Scheme 1). Our laboratory has previously demonstrated an effective strategy for thermodynamically leveraged etheric and esteric C–O bond hydrogenolysis using a tandem metal triflate + supported palladium catalytic system.(11) A homogeneous M(OTf)n catalyst mediates endothermic ether or near thermoneutral ester C–O bond scission (the reverse of hydroelementation), which is coupled to exothermic Pd-catalyzed hydrogenation of the resulting C=C unsaturation, driving the overall process downhill. We next asked whether this tandem system might be applicable to cleaving the β-O-4 aryl-ether bond in lignin and lignin models. The promising results of that investigation are communicated here.« less

Surface hydrophobicity and acidity effect on alumina catalyst in catalytic methanol dehydration reaction

PubMed Central

Osman, Ahmed I; Thompson, Jillian; Halawy, Samih A; Mohamed, Mohamed A

2017-01-01

Abstract BACKGROUND Methanol to dimethyl ether (MTD) is considered one of the main routes for the production of clean bio‐fuel. The effect of copper loading on the catalytic performance of different phases of alumina that formed by calcination at two different temperatures was examined for the dehydration of methanol to dimethyl ether (DME). RESULTS A range of Cu loadings of (1, 2, 4, 6, 10 and 15% Cu wt/wt) on Al2O3 calcined at 350 and 550 °C were prepared and characterized by TGA, XRD, BET, NH3‐TPD, TEM, H2‐TPR, SEM, EDX, XPS and DRIFT‐Pyridine techniques. The prepared catalysts were used in a fixed bed reactor under reaction conditions in which the temperature ranged from 180–300 °C with weight hourly space velocity (WHSV) = 12.1 h‐1. It was observed that all catalysts calcined at 550 °C (γ‐Al2O3 support phase) exhibited higher activity than those calcined at 350 °C (γ‐AlOOH), and this is due to the phase support change. Furthermore, the optimum Cu loading was found to be 6% Cu/γ‐Al2O3 with this catalyst also showing a high degree of stability under steady state conditions and this is attributed to the enhancement in surface acidity and hydrophobicity. CONCLUSION The addition of copper to the support improved the catalyst properties and activity. For all the copper modified catalysts, the optimum catalyst with high degree of activity and stability was 6% copper loaded on gamma alumina. © 2017 The Authors. Journal of Chemical Technology & Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. PMID:29200585

Alkyl Azides, Diazides, Haloazides and Bridged Polycyclic Diazides

DTIC Science & Technology

1991-05-16

temperature. Most of the methyl ether was removed during this process. The ehtyl ether was distilled from the reaction mixture using a water aspirator into a...Street PROGRAM IPROJECT ITASK IWORK li1111? ArliiqIoh, VA 22217-5000 EILIMENT NO I NO. I oACCESSION P10) Alkyl Azides, Dlazides, laloazides and...REPRODUCE LEGIBLY. ALKYL AZIDES, DIAZIDES, HALOAZIDES AND BRIDGED POLYCYCLIC DIAZIDES Final REPORTe July 1, 1989-November 14, 1990 A6jd.%4gi0 F’or

The Path of Carbon in Photosynthesis XIII. pH Effects in C{sup 14}O{sub 2} Fixation by Scenedesmus

DOE R&D Accomplishments Database

Ouellet, C.; Benson, A. A.

1951-10-23

The rates of photosynthesis and dark fixation of C{sup 14}O{sub 2} in Scenedesmus have been compared in dilute phosphate buffers of 1.6 to 11.4 pH; determination of C{sup 14} incorporation into the various products shows enhancement of uptake in an acid medium into sucrose, polysaccharides, alanine and serine, in an alkaline medium into malic asparctic acids. kinetic experiments at extreme pH values suggest that several paths are available for CO{sub 2} assimilation. A tentative correlation of the results with the pH optima of some enzymes and resultant effects upon concentrations of intermediates is presented.

Solvation effects on alanine dipeptide: A MP2/cc-pVTZ//MP2/6-31G** study of (Phi, Psi) energy maps and conformers in the gas phase, ether, and water.

PubMed

Wang, Zhi-Xiang; Duan, Yong

2004-11-15

The effects of solvation on the conformations and energies of alanine dipeptide (AD) have been studied by ab initio calculations up to MP2/cc-pVTZ//MP2/6-31G**, utilizing the polarizable continuum model (PCM) to mimic solvation effects. The energy surfaces in the gas phase, ether, and water bear similar topological features carved by the steric hindrance, but the details differ significantly due to the solvent effects. The gas-phase energy map is qualitatively consistent with the Ramachandran plot showing seven energy minima. With respect to the gas-phase map, the significant changes of the aqueous map include (1) the expanded low-energy regions, (2) the emergence of an energy barrier between C5-beta and alpha(R)-beta(2) regions, (3) a clearly pronounced alpha(R) minimum, a new beta-conformer, and the disappearance of the gas-phase global minimum, and (4) the shift of the dominant region in LEII from the gas-phase C7(ax) region to the alpha(L) region. These changes bring the map in water to be much closer to the Ramachandran plot than the gas-phase map. The solvent effects on the geometries include the elongation of the exposed N-H and C=O bonds, the shortening of the buried HN--CO peptide bonds, and the enhanced planarity of the peptide bonds. The energy surface in ether has features similar to those both in the gas phase and in water. The free energy order computed in the gas phase and in ether is in good agreement with experimental studies that concluded that C5 and C7(eq) are the dominant species in both the gas phase and nonpolar solvents. The free energy order in water is consistent with the experimental observation that the dominant C7(eq) in the nonpolar solvent was largely replaced by P(II)-like (i.e., beta) and alpha(R) in the strong polar solvents. Based on calculations on AD + 4H(2)O and other AD-water clusters, we suggest that explicit water-AD interactions may distort C5 and beta (or alpha(R) and beta) to an intermediate conformation. Our analysis also shows that the PCM calculations at the MP2/cc-pVTZ//MP2/6-31G** level give good descriptions to the bulk solvent polarization effect. The results presented in this article should be of sufficient quality to characterize the peptide bonds in the gas phase and solvents. The energy surfaces may serve as the basis for developing of strategies enabling the inclusion of solvent polarization in the force field.

A novel fluorescent probe for Cr3 + based on rhodamine-crown ether conjugate and its application to drinking water examination and bioimaging

NASA Astrophysics Data System (ADS)

Diao, Quanping; Ma, Pinyi; Lv, Linlin; Li, Tiechun; Wang, Xinghua; Song, Daqian

2016-03-01

A trivalent chromium (Cr3 +) fluorescence probe (RhC) was designed and synthesized via Schiff base reaction based on rhodamine-crown ether conjugate. This probe displayed a favorable selectivity for Cr3 + over a range of other common metal ions in DMF/H2O (3:7, v/v; PBS buffer 50 mmol L- 1; pH = 6.8) solution, leading to prominent fluorescence "OFF-ON" switching of the rhodamine fluorophore. The limit of detection was calculated to be 1.5 μmol L- 1 (S/N = 3). The binding ratio of RhC-Cr3 + complex was determined to be 1:2 according to the Job's plot and HR-MS. The probe was successfully applied to examination of Cr3 + in drinking water spiked samples. The average recoveries ranged from 104.9% to 106.9% at spiked concentration level of 10.00 μmol L- 1, and the obtained results were consistent with those obtained using atomic absorption spectrometry (AAS). Moreover, bioimaging experiments showed that RhC can sense the Cr3 + in living cells with a fluorescence enhancement signal.

Ethyl 4-(2-fur-yl)-2-oxochroman-3-carboxyl-ate.

PubMed

Prabhakar, Maddela; Reddy, J S N; Kumar, N Ravi; Ganesh, S Viswanadha; Solomon, K Anand

2010-05-12

The title compound, C(16)H(14)O(5), was prepared from the reaction of 3-carbethoxy-coumarin with furan in the presence of AlCl(3) as catalyst. In the crystal, inter-molecular C-H⋯O hydrogen-bonding inter-actions between four mol-ecules lead to a tetra-mer in the unit cell. The furan ring is anti-periplanar [C-C-C-O = 167.9 (13)°] and the ethoxy-carbonyl group is (-)anti-clinal [C-C-C-O = -128.6 (14)°] to the lactone ring.

Syntheses, structures, and vibrational spectroscopy of the two-dimensional iodates Ln(IO 3) 3 and Ln(IO 3) 3(H 2O) ( Lndbnd Yb, Lu)

NASA Astrophysics Data System (ADS)

Assefa, Zerihun; Ling, Jie; Haire, Richard G.; Albrecht-Schmitt, Thomas E.; Sykora, Richard E.

2006-12-01

The reaction of Lu 3+ or Yb 3+ and H 5IO 6 in aqueous media at 180 °C leads to the formation of Yb(IO 3) 3(H 2O) or Lu(IO 3) 3(H 2O), respectively, while the reaction of Yb metal with H 5IO 6 under similar reaction conditions gives rise to the anhydrous iodate, Yb(IO 3) 3. Under supercritical conditions Lu 3+ reacts with HIO 3 and KIO 4 to yield the isostructural Lu(IO 3) 3. The structures have been determined by single-crystal X-ray diffraction. Crystallographic data are (Mo Kα, λ=0.71073 Å): Yb(IO 3) 3, monoclinic, space group P2 1/ n, a=8.6664(9) Å, b=5.9904(6) Å, c=14.8826(15) Å, β=96.931(2)°, V=766.99(13), Z=4, R( F)=4.23% for 114 parameters with 1880 reflections with I>2 σ( I); Lu(IO 3) 3, monoclinic, space group P2 1/ n, a=8.6410(9), b=5.9961(6), c=14.8782(16) Å, β=97.028(2)°, V=765.08(14), Z=4, R( F)=2.65% for 119 parameters with 1756 reflections with I>2 σ( I); Yb(IO 3) 3(H 2O), monoclinic, space group C2/ c, a=27.2476(15), b=5.6296(3), c=12.0157(7) Å, β=98.636(1)°, V=1822.2(2), Z=8, R( F)=1.51% for 128 parameters with 2250 reflections with I>2 σ( I); Lu(IO 3) 3(H 2O), monoclinic, space group C2/ c, a=27.258(4), b=5.6251(7), c=12.0006(16) Å, β=98.704(2)°, V=1818.8(4), Z=8, R( F)=1.98% for 128 parameters with 2242 reflections with I>2 σ( I). The f elements in all of the compounds are found in seven-coordinate environments and bridged with monodentate, bidentate, or tridentate iodate anions. Both Lu(IO 3) 3(H 2O) and Yb(IO 3) 3(H 2O) display distinctively different vibrational profiles from their respective anhydrous analogs. Hence, the Raman profile can be used as a complementary diagnostic tool to discern the different structural motifs of the compounds.

Characterization of hallucinogenic phenethylamines using high-resolution mass spectrometry for non-targeted screening purposes.

PubMed

Pasin, Daniel; Cawley, Adam; Bidny, Sergei; Fu, Shanlin

2017-10-01

Hallucinogenic phenethylamines such as 2,5-dimethoxyphenethylamines (2C-X) and their N-(2-methoxybenzyl) derivatives (25X-NBOMe) have seen an increase in novel analogues in recent years. These rapidly changing analogues make it difficult for laboratories to rely on traditional targeted screening methods to detect unknown new psychoactive substances (NPS). In this study, twelve 2C-X, six 2,5-dimethoxyamphetamines (DOX), and fourteen 25X-NBOMe derivatives, including two deuterated derivatives (2C-B-d 6 and 25I-NBOMe-d 9 ), were analyzed using ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS). Collision-induced dissociation (CID) experiments were performed using collision energies set at 10, 20, and 40 eV. For 2C-X and DOX derivatives, common losses were observed including neutral and radical losses such as NH 3 (17.0265 Da), •CH 6 N (32.0500 Da), C 2 H 7 N (45.0578 Da) and C 2 H 9 N (47.0735 Da). 2C-X derivatives displayed common product ions at m/z 164.0837 ([C 10 H 12 O 2 ] +• ), 149.0603 ([C 9 H 9 O 2 ] + ), and 134.0732 ([C 9 H 10 O] +• ) while DOX derivatives had common product ions at m/z 178.0994 ([C 11 H 14 O 2 ] +• ), 163.0754 ([C 10 H 11 O 2 ] + ), 147.0804 ([C 10 H 11 O] + ), and 135.0810 ([C 9 H 11 O] + ). 25X-NBOMe had characteristic product ions at m/z 121.0654 ([C 8 H 9 O] + ) and 91.0548 ([C 7 H 7 ] + ) with minor common losses corresponding to 2-methylanisole (C 8 H 10 O, 122.0732 Da), 2-methoxybenzylamine (C 8 H 11 NO, 137.0847 Da), and •C 9 H 14 NO (152.1074 Da). Novel analogues of the selected classes can be detected by applying neutral loss filters (NLFs) and extracting the common product ions. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

Measurement of Temperature Dependence for Vapor Pressures of Seventeen OH-PBDEs and Eleven MeO-PBDEs by Gas Chromatographic Method.

PubMed

Zhao, Hongxia; Xie, Qing; Chen, Xiuying; Qu, Baocheng; Jiang, Jingqiu

2016-05-01

Hydroxylated polybromodiphenyl ethers (OH-PBDEs) and methoxylated polybrominated diphenyl ethers (MeO-PBDEs) are emerging organic pollutants. Supercooled liquid vapor pressures (p L) and enthalpies of vaporization (∆vap H) for seventeen OH-PBDEs and eleven MeO-PBDEs were determined by a gas chromatographic technique. p L at 298 K ranged from 0.0173 Pa for 2'-OH-BDE3 to 2.32 × 10(-7) Pa for 3'-OH-BDE154 and they are approximately one order of magnitude smaller than those determined for the counterpart polybrominated diphenyl ethers (PBDEs). ∆vap H was in the range of 76-121 kJ/mol. The temperature dependence of p L was measured by fitting the experimental data with the log(p L/Pa) = a/(T/K) + b equation, and this corresponds to a 50-265 times higher p L value at 0 versus 30°C. Using fundamental quantum chemical descriptors, two quantitative structure-property relationship models (Q cum > 0.935) were developed to estimate p L at any temperature for the additional OH- and MeO-PBDE congeners.

Synthesis of Potential Prophylactic Agents Against Cyanide Intoxication

DTIC Science & Technology

1993-05-06

34/21) S 2,6-C 2 Ad 72 mp 139" CsH3C12NO 163 (lie mp 139.5-140.5") 6 4-OMe A 45 Mp 73-79e CH 7N0% (lit t mp 73-741) 7 2-OMe A 50 Mp 66" C*HNO 126 (litf...Form. Found cation. Compd. No. Reactants Yield, % Mp, *C (cation.anion) %C %H %N anion Part A. 1 -Alkoxypyridinium salts. 14 2,3-Mes, 87 120-122 CH ...111 + 4(C6H6CVs O, 28.62 3.22 4.40 ..... (MeO)2SO2 _OSO 2 CH s ) is 4-OMe,6 + 78 46-48 CSH 121NO 2 34.18 4.30 4.91 154, 126 Ed (CsH12NO2-) 34.02

40 CFR Appendix - Tables to Part 132

Code of Federal Regulations, 2012 CFR

2012-07-01

...-Bromophenyl phenyl ether Butyl benzyl phthalate Cadmium Carbon tetrachloride; tetrachloromethane Chlorobenzene...) phthalate Diazinon 1,2:5,6-Dibenzanthracene; dibenz[a,h]anthracene Dibutyl phthalate; di-n-butyl phthalate 1...-dichloropropylene Diethyl phthalate 2,4-Dimethylphenol; 2,4-xylenol Dimethyl phthalate 4,6-Dinitro-o-cresol; 2...

Flavonolignans and other constituents from Lepidium meyenii with activities in anti-inflammation and human cancer cell lines.

PubMed

Bai, Naisheng; He, Kan; Roller, Marc; Lai, Ching-Shu; Bai, Lu; Pan, Min-Hsiung

2015-03-11

From the roots of Lepidium meyenii Walpers (Brassicaceae) have been isolated and identified 2 flavonolignans, tricin 4'-O-[threo-β-guaiacyl-(7″-O-methyl)-glyceryl] ether (1) and tricin 4'-O-(erythro-β-guaiacyl-glyceryl) ether (2), along with 11 other known compounds, tricin (3), pinoresinol (4), 4-hydroxycinnamic acid (5), guanosine (6), glucotropaeolin (7), desulfoglucotropaeolin (8), 3-hydroxybenzylisothiocyanate (9), malic acid benzoate (10), 5-(hydroxymethyl)-2-furfural (11), d-phenylalanine (12), and vanillic acid 4-O-β-d-glucoside (13). Structures were elucidated on the basis of NMR and MS data. Some isolates and previously isolated lepidiline B (14) were tested for cytotoxicity in a small panel of human cancer cell lines (Hep G2, COLO 205, and HL-60) and for anti-inflammatory activities in LPS-treated RAW 264.7 macrophage. Among them, compounds 1 and 14 were modestly active for inhibiting nitrite production in macrophage. Compounds 1, 14, and 3 were demonstrated to be selectively active against HL-60 cells with IC50 values of 40.4, 52.0, and 52.1 μM, respectively.

Heliolactone, a non-sesquiterpene lactone germination stimulant for root parasitic weeds from sunflower.

PubMed

Ueno, Kotomi; Furumoto, Toshio; Umeda, Shuhei; Mizutani, Masaharu; Takikawa, Hirosato; Batchvarova, Rossitza; Sugimoto, Yukihiro

2014-12-01

Root exudates of sunflower (Helianthus annuus L.) line 2607A induced germination of seeds of root parasitic weeds Striga hermonthica, Orobanche cumana, Orobanche minor, Orobanche crenata, and Phelipanche aegyptiaca. Bioassay-guided purification led to the isolation of a germination stimulant designated as heliolactone. FT-MS analysis indicated a molecular formula of C20H24O6. Detailed NMR spectroscopic studies established a methylfuranone group, a common structural component of strigolactones connected to a methyl ester of a C14 carboxylic acid via an enol ether bridge. The cyclohexenone ring is identical to that of 3-oxo-α-ionol and the other part of the molecule corresponds to an oxidized carlactone at C-19. It is a carlactone-type molecule and functions as a germination stimulant for seeds of root parasitic weeds. Heliolactone induced seed germination of the above mentioned root parasitic weeds, while dehydrocostus lactone and costunolide, sesquiterpene lactones isolated from sunflower root exudates, were effective only on O. cumana and O. minor. Heliolactone production in aquacultures increased when sunflower seedlings were grown hydroponically in tap water and decreased on supplementation of the culture with either phosphorus or nitrogen. Costunolide, on the other hand, was detected at a higher concentration in well-nourished medium as opposed to nutrient-deficient media, thus suggesting a contrasting contribution of heliolactone and the sesquiterpene lactone to the germination of O. cumana under different soil fertility levels. Copyright © 2014 Elsevier Ltd. All rights reserved.

Preparation and Characterization of Activated Alumina

NASA Astrophysics Data System (ADS)

Rabia, A. R.; Ibrahim, A. H.; Zulkepli, N. N.

2018-03-01

Activated alumina is a high surface area and highly porous form of aluminum oxide that can be employed for contaminant species adsorb from ether gases or liquids without changing its form. The research in getting this material has generated huge interested. Thus, this paper presented preparation of activated alumina from chemical process. Pure aluminum (99.9% pure) reacted at room temperature with an aqueous NaOH in a reactor to produce a solution of sodium aluminate (NaAlO2). This solution was passed through filter paper and the clear filtrate was neutralized with H2SO4, to pH 6, 7 or 8, resulting in the precipitation of a white gel, Al(OH)3·XH2O. The washed gel for sulfate ions were dried at 80 °C for 6 h, a 60 mesh sieve was to separate and sort them into different sizes. The samples were then calcined (burn) for 3h in a muffle furnace, in air, at a heating rate of 2 °C min-1. The prepared activated alumina was further characterized for better understanding of its physical properties in order to predict its chemical mechanism.

Effects of NOx on the molecular composition of secondary organic aerosol formed by the ozonolysis and photooxidation of α-pinene

NASA Astrophysics Data System (ADS)

Park, Jun-Hyun; Babar, Zaeem Bin; Baek, Sun Jong; Kim, Hyun Sik; Lim, Ho-Jin

2017-10-01

The molecular composition of secondary organic aerosol (SOA), obtained from the ozonolysis and photooxidation of α-pinene, was investigated using ultrahigh-resolution Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS) in negative ion mode electrospray ionization (ESI). SOA formation was performed in an indoor smog chamber. The molecular formulae of individual species were identified on the basis of the measured ionic mass using guidelines, such as number of atoms, elemental ratios, and the nitrogen rule. In each of the SOAs obtained, 815-3501 monomeric and oligomeric (mainly dimeric) species were identified below m/z 800. From ozonolysis, mainly 95% of the typical oxygenated species (CHO) were detected, whereas from photooxidation under high NOx conditions, 32% of nitrogen-containing species (CHON) were detected. Several common intense species (e.g., C9H14O6, C10H14O6, C10H16O5, C17H26O7, C19H28O9, C10H15NO8, and C10H15NO9) could be listed as candidate tracers for the conventional tracers for α-pinene SOA. The increased percentage of CHON as a primary effect of NOx on the SOA composition evidently affected other physicochemical parameters, such as elemental ratios (i.e., O/C, H/C, and N/C), the double-bond equivalent (DBE), the carbon oxidation state (OSC), and the organic-mass-to-carbon ratio (OM/OC). The O/C and OM/OC for CHON were greater than those observed for CHO, indicating that nitrogen preferentially exists in the oxidized form (e.g., -ONO2). The complexity of oligomerization was observed in DBE and OM/OC according to the number of carbon atoms.

New perspectives in the PAW/GIPAW approach: J(P-O-Si) coupling constants, antisymmetric parts of shift tensors and NQR predictions.

PubMed

Bonhomme, Christian; Gervais, Christel; Coelho, Cristina; Pourpoint, Frédérique; Azaïs, Thierry; Bonhomme-Coury, Laure; Babonneau, Florence; Jacob, Guy; Ferrari, Maude; Canet, Daniel; Yates, Jonathan R; Pickard, Chris J; Joyce, Siân A; Mauri, Francesco; Massiot, Dominique

2010-12-01

In 2001, Pickard and Mauri implemented the gauge including projected augmented wave (GIPAW) protocol for first-principles calculations of NMR parameters using periodic boundary conditions (chemical shift anisotropy and electric field gradient tensors). In this paper, three potentially interesting perspectives in connection with PAW/GIPAW in solid-state NMR and pure nuclear quadrupole resonance (NQR) are presented: (i) the calculation of J coupling tensors in inorganic solids; (ii) the calculation of the antisymmetric part of chemical shift tensors and (iii) the prediction of (14)N and (35)Cl pure NQR resonances including dynamics. We believe that these topics should open new insights in the combination of GIPAW, NMR/NQR crystallography, temperature effects and dynamics. Points (i), (ii) and (iii) will be illustrated by selected examples: (i) chemical shift tensors and heteronuclear (2)J(P-O-Si) coupling constants in the case of silicophosphates and calcium phosphates [Si(5)O(PO(4))(6), SiP(2)O(7) polymorphs and α-Ca(PO(3))(2)]; (ii) antisymmetric chemical shift tensors in cyclopropene derivatives, C(3)X(4) (X = H, Cl, F) and (iii) (14)N and (35)Cl NQR predictions in the case of RDX (C(3)H(6)N(6)O(6)), β-HMX (C(4)H(8)N(8)O(8)), α-NTO (C(2)H(2)N(4)O(3)) and AlOPCl(6). RDX, β-HMX and α-NTO are explosive compounds. Copyright © 2010 John Wiley & Sons, Ltd.

A moderate distortion of the `picket-fence' porphyrin (cryptand-222)potassium chlorido[meso-α,α,α,α-tetrakis(o-pivalamidophenyl)porphyrinato]ferrate(II) n-hexane monosolvate.

PubMed

Yu, Qiang; Liu, Diansheng; Li, Xiangjun; Li, Jianfeng

2015-10-01

As representative porphyrin model compounds, the structures of `picket-fence' porphyrins have been studied intensively. The title solvated complex salt {systematic name: (4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane)potassium(I) [5,10,15,20-tetrakis(2-tert-butanamidophenyl)porphyrinato]iron(II) n-hexane monosolvate}, [K(C18H36N2O6)][Fe(C64H64N8O4)Cl]·C6H14 or [K(222)][Fe(TpivPP)Cl]·C6H14 [222 is cryptand-222 or 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane, and TpivPP is meso-α,α,α,α-tetrakis(o-pivalamidophenyl)porphyrinate(2-)], [K(222)][Fe(TpivPP)Cl]·C6H14, is a five-coordinate high-spin iron(II) picket-fence porphyrin complex. It crystallizes with a potassium cation chelated inside a cryptand-222 molecule; the average K-O and K-N distances are 2.81 (2) and 3.05 (2) Å, respectively. One of the protecting tert-butyl pickets is disordered. The porphyrin plane presents a moderately ruffled distortion, as suggested by the atomic displacements. The axial chloride ligand is located inside the molecular cavity on the hindered porphyrin side and the Fe-Cl bond is tilted slightly off the normal to the porphyrin plane by 4.1°. The out-of-plane displacement of the metal centre relative to the 24-atom mean plane (Δ24) is 0.62 Å, indicating a noticeable doming of the porphyrin core.

Effect of Methyl Substitution on the N-H···O Interaction in Complexes of Pyrrole with Water, Methanol, and Dimethyl Ether: Matrix Isolation Infrared Spectroscopy and ab Initio Computational Studies.

PubMed

Sarkar, Shubhra; Ramanathan, N; Sundararajan, K

2018-03-08

Hydrogen-bonded interactions of pyrrole with water and methanol have been studied using matrix isolation infrared spectroscopy and compared with the calculation performed on dimethyl ether. Computations carried out at MP2/aug-cc-pVDZ level of theory yielded two minima for the pyrrole-water and pyrrole-methanol complexes. The global and local minima correspond to the N-H···O and O-H···π complexes, respectively, where the N-H group of pyrrole interacts with oxygen of water/methanol and O-H of water and methanol interacts with the π cloud of pyrrole. Computations performed on the pyrrole-dimethyl ether gave only N-H···O type complex. From the experimental vibrational wavenumber shifts in the N-H stretching and N-H bending modes of pyrrole, as well as in the O-H stretching modes of water and methanol, the 1:1 N-H···O complexes were discerned. The strength of the N-H···O hydrogen bond and the corresponding shift in the N-H stretching vibrational wavenumbers increases in the order pyrrole-water < pyrrole-methanol < pyrrole-dimethyl ether, where a proton is successively replaced by a methyl group. Apart from the 1:1 complexes, higher clusters of 2:1 and 1:2 pyrrole-water and pyrrole-methanol complexes were also generated in N 2 matrix. Atoms in molecules and natural bond orbital analyses were carried out at the MP2/aug-cc-pVDZ level to understand the nature of interaction in the 1:1 pyrrole-water, pyrrole-methanol and pyrrole-dimethyl ether complexes.

Organic Compounds Produced by Photolysis of Realistic Interstellar and Cometary Ice Analogs Containing Methanol

NASA Astrophysics Data System (ADS)

Bernstein, Max P.; Sandford, Scott A.; Allamandola, Louis J.; Chang, Sherwood; Scharberg, Maureen A.

1995-11-01

The infrared (IR) spectra of ultraviolet (UV) and thermally processed, methanol-containing interstellar/ cometary ice analogs at temperatures from 12 to 300 K are presented. Infrared spectroscopy, 1H and 13C nuclear magnetic resonance (NMR) spectroscopy, and gas chromatography-mass spectrometry indicate that CO (carbon monoxide), CO2 (carbon dioxide), CH4 (methane), HCO (the formyl radical), H2CO (formaldehyde), CH3CH2OH (ethanol), HC(=O)NH2 (formamide), CH3C(=O)NH2 (acetamide), and R-C=-N (nitriles) are formed. In addition, the organic materials remaining after photolyzed ice analogs have been warmed to room temperature contain (in rough order of decreasing abundance), (1) hexamethylenetetramine (HMT, C6H12N4), (2) ethers, alcohols, and compounds related to polyoxymethylene {POM, ( CH2O )n}, and (3) ketones {R-C(=O)-R'} and amides {H2NC(=O)-R}. Most of the carbon in these residues is thought to come from the methanol in the original ice. Deuterium and 13C isotopic labeling demonstrates that methanol is definitely the source of carbon in HMT. High concentrations of HMT in interstellar and cometary ices could have important astrophysical consequences. The ultraviolet photolysis of HMT frozen in H2O ice readily produces the "XCN" band observed in the spectra of protostellar objects and laboratory ices, as well as other nitriles. Thus, HMT may be a precursor of XCN and a source of CN in comets and the interstellar medium. Also, HMT is known to hydrolyze under acidic conditions to yield ammonia, formaldehyde, and amino acids. Thus, HMT may be a significant source of prebiogenic compounds on asteroidal parent bodies. A potential mechanism for the radiative formation of HMT in cosmic ices is outlined.

Metabolic inactivation of five glycidyl ethers in lung and liver of humans, rats and mice in vitro.

PubMed

Boogaard, P J; de Kloe, K P; Bierau, J; Kuiken, G; Borkulo, P E; Watson, W P; van Sittert, N J

2000-05-01

1. Some glycidyl ethers (GE) have been shown to be direct mutagens in short-term in vitro tests and consequently GE are considered to be potentially mutagenic in vivo. However, GE may be metabolically inactivated in the body by two different enzymatic routes: conjugation of the epoxide moiety with the endogenous tripeptide glutathione (GSH) catalysed by glutathione S-transferase (GST) or hydrolysis of the epoxide moiety catalysed by epoxide hydrolase (EH). 2. The metabolic inactivation of five different GE, the diglycidyl ethers of bisphenol A (BADGE), 4,4'-dihydroxy-3,3',5,5'-tetramethylbiphenyl (Epikote YX4000) and 1,6-hexanediol (HDDGE) and the GE of 1-dodecanol (C12GE) and o-cresol (o-CGE), has been studied in subcellular fractions of human, C3H mouse and F344 rat liver and lung. 3. All GE were chemically very stable and resistant to aqueous hydrolysis, but were rapidly hydrolysed by EH in cytosolic and microsomal fractions of liver and lung. The aromatic GE were very good substrates for EH. In general, microsomal EH is more efficient than cytosolic EH in hydrolysis of GE, and human microsomes are more efficient than rodent microsomes. 4. The more water-soluble GE, o-CGE and HDDGE, were good substrates for GST whereas the more lipophilic GE, YX4000 and C12GE, were poor substrates for GST. In general, rodents are more efficient in GSH conjugation of GE than humans. 5. In general, the epoxide groups of YX4000 are the most and those of HDDGE the least efficiently inactivated of the five GE under study. For the other three GE no general trend was observed: the relative efficiency of inactivation varied with organ and species. 6. The large variation in metabolism observed with five representative GE indicate that GE have variable individual properties and should not be considered as a single, homogenous class of compounds.

Crystal structure of (eth­oxy­ethyl­idene)di­methyl­aza­nium ethyl sulfate

PubMed Central

Tiritiris, Ioannis; Saur, Stefan; Kantlehner, Willi

2015-01-01

In the title salt, C6H14NO+·C2H5SO4 −, the C—N bond lengths in the cation are 1.2981 (14), 1.4658 (14) and 1.4707 (15) Å, indicating double- and single-bond character, respectively. The C—O bond length of 1.3157 (13) Å shows double-bond character, indicating charge delocalization within the NCO plane of the iminium ion. In the crystal, C—H⋯O hydrogen bonds between H atoms of the cations and O atoms of neighbouring ethyl sulfate anions are present, generating a three-dimensional network. PMID:26870525

The Ruthenostannylene Complex [Cp*(IXy)H2 Ru-Sn-Trip]: Providing Access to Unusual Ru-Sn Bonded Stanna-imine, Stannene, and Ketenylstannyl Complexes.

PubMed

Liu, Hsueh-Ju; Ziegler, Micah S; Tilley, T Don

2015-05-26

Reactivity studies of the thermally stable ruthenostannylene complex [Cp*(IXy)(H)2 Ru-Sn-Trip] (1; IXy=1,3-bis(2,6-dimethylphenyl)imidazol-2-ylidene; Cp*=η(5) -C5 Me5 ; Trip=2,4,6-iPr3 C6 H2 ) with a variety of organic substrates are described. Complex 1 reacts with benzoin and an α,β-unsaturated ketone to undergo [1+4] cycloaddition reactions and afford [Cp*(IXy)(H)2 RuSn(κ(2) -O,O-OCPhCPhO)Trip] (2) and [Cp*(IXy)(H)2 RuSn(κ(2) -O,C-OCPhCHCHPh)Trip] (3), respectively. The reaction of 1 with ethyl diazoacetate resulted in a tin-substituted ketene complex [Cp*(IXy)(H)2 RuSn(OC2 H5 )(CHCO)Trip] (4), which is most likely a decomposition product from the putative ruthenium-substituted stannene complex. The isolation of a ruthenium-substituted stannene [Cp*(IXy)(H)2 RuSn(=Flu)Trip] (5) and stanna-imine [Cp*(IXy)(H)2 RuSn(κ(2) -N,O-NSO2 C6 H4 Me)Trip] (6) complexes was achieved by treatment of 1 with 9-diazofluorene and tosyl azide, respectively. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

3-Chloro-4-fluoro­anilinium picrate

PubMed Central

Sarojini, Balladka K.; Narayana, Badiadka; Yathirajan, Hemmige S.; Gerber, Thomas; van Brecht, Benjamin; Betz, Richard

2013-01-01

In the title picrate salt of a dihalogenated aniline derivative, C6H6ClF+·C6H2N3O7 −, the intra­cyclic C—C—C angles in the picrate anion cover a broad range [111.95 (12)–125.38 (13)°], while those in the aromatic cation span a much narrower range [118.25 (14)–122.33 (13)°]. In the crystal, classical N—H⋯O hydrogen bonds, as well as C—H⋯O contacts, connect the ions into layers parallel to (001). PMID:23424519

Bioactive Lignans from Zanthoxylum alatum Roxb. stem bark with cytotoxic potential.

PubMed

Mukhija, Minky; Lal Dhar, Kanaya; Nath Kalia, Ajudhia

2014-02-27

Zanthoxylum alatum is used in traditional medicinal systems for number of disorders like cholera, diabetes, cough, diarrhea, fever, headache, microbial infections, toothache, inflammation and cancer. The aim of the present study was to evaluate Zanthoxylum alatum stem bark for its cytotoxic potential and to isolate the bioactive constituents. Cytotoxicity of the different extracts and isolated compounds was studied on lung carcinoma cell line (A549) and pancreatic carcinoma cell line (MIA-PaCa) using MTT assay. Isolation of compounds from most active extract (petroleum ether) was done on silica gel column. Structure elucidation was done by using various spectrophotometric techniques like UV, IR, (1)H NMR, (13)C NMR and mass spectroscopy. The type of cell death caused by most active compound C was explored by fluorescence microscopy using the acridine orange/ethidium bromide method. Petroleum ether extract of plant has shown significant cytotoxic potential. Three lignans sesamin (A), kobusin (B), and 4'O demethyl magnolin (C) has been isolated. All lignans showed cytotoxic activities in different ranges. Compound C was the novel bioactive compound from a plant source and found to be most active. In apoptosis study, treatment caused typical apoptotic morphological changes. It enhances the apoptosis at IC50 dose (21.72 µg/mL) however showing necrotic cell death at higher dose after 24h on MIA-PaCa cell lines. Petroleum ether extract (60-80 °C) of Zanthoxylum alatum has cytotoxic potential. The lignans isolated from the petroleum ether extract were responsible for the cytotoxic potential of the extract. 4'O demethyl magnolin was novel compound from Zanthoxylum alatum. Hence the Zanthoxylum alatum can be further explored for the development of anticancer drug. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Synthesis and physico-chemical studies on neodymium(III) and samarium(III) complexes with tetraaza macrocyclic ligands

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

Goel, S.; Pandey, U.K.; Pandey, O.P.

1988-05-01

Reactions of neodymium trichloride and samarium trichloride with 6,7,13,14-R/sub 4/ - 3,10-X/sub 2/-(14)-5,7,12,14-tetraene-1,5,8,12-N/sub 4/-(2,4,9,11-N/sub 4/) (R = CH/sub 3/, X = 0 (L/sub 1//sup (1)/); R = C/sub 6/H/sub 5/, X = O (L/sub 1//sup (2)/); R = CH/sub 3/, X = S(L/sub 2//sup (1)/)) and R = C/sub 6/H/sub 5/, X = S(/sub 2//sup (2)/)) have been studied in ethanol and complexes of the type (M(L/sub 1//sup (1)/ or L/sub 1//sup (2)/))Cl/sub 3/ and (M(L/sub 2//sup (1)/ or L/sub 2//sup (2)/)(H/sub 2/O)/sub 2/)Cl/sub 3/ (M = Nd(III) and Sm(III)) have been isolated. In addition, macrocyclic complexes of Nd(III) andmore » Sm(III) with another series of tetraaza ligands, viz, 5,6,11,12-R/sub 4/-3,8-X/sub 2/-(12)-4,6,10,12-tetraene-1,4,7,10-N/sub 4/-(2,9-N/sub 2/) (R = CH/sub 3/, X = O (L/sub 3//sup (1)/); R = C/sub 6/H/sub 5/, X = O(L/sub 3//sup (2)/); R = CH/sub 3/, X = S(L/sub 4//sup (1)/); R = C/sub 6/H/sub 5/, X = S(L/sub 4//sup (2)/)), formulated as (M(L/sub 3//sup (1)/, L/sub 3//sup (2)/, L/sub 4//sup (1)/ or L/sub 4//sup (2)/)(H/sub 2/O)/sub 2/)Cl/sub 3/ (M = Nd(III) and Sm(III)) have been prepared by template condensation of Nd(III) and Sm(III) complexes of diacetylbis(semicarbazonethiosemicarbazone) or benzilibis(semicarbazonethiosemicarbazone) with diacetyl or benzil. The complexes have been identified by elemental analysis, electrical conductance, spectral and thermal measurements.« less

Isotopic Ratios of H, C, N, O, and S in Comets C2012 F6 (lemmon) and C2014 Q2 (lovejoy) * ** ***

NASA Technical Reports Server (NTRS)

Biver, N.; Moreno, R.; Sandqvist, Aa.; Bockelee-Morvan, D.; Colom, P.; Crovisier, J.; Lis, D. C.; Bossier, J.; Debout, V.; Paubert, G.;

30 CFR 57.5006 - Air Quality-Surface Only [Reserved

Code of Federal Regulations, 2010 CFR

2010-07-01

... acceptable to the Secretary. (a) Carbon tetrachloride, (b) Phenol, (c) 4-Nitrobiphenyl, (d) Alpha..., (h) Bis (chloromethyl) ether, (i) Beta-napthylamine, (j) Benzidine, (k) 4-Aminodiphenyl, (l) Ethyleneimine, (m) Beta-propiolactone, (n) 2-Acetylaminofluorene, (o) 4-Dimethylaminobenzene, and (p) N...

30 CFR 57.5006 - Air Quality-Surface Only [Reserved

Code of Federal Regulations, 2011 CFR

2011-07-01

... acceptable to the Secretary. (a) Carbon tetrachloride, (b) Phenol, (c) 4-Nitrobiphenyl, (d) Alpha..., (h) Bis (chloromethyl) ether, (i) Beta-napthylamine, (j) Benzidine, (k) 4-Aminodiphenyl, (l) Ethyleneimine, (m) Beta-propiolactone, (n) 2-Acetylaminofluorene, (o) 4-Dimethylaminobenzene, and (p) N...

Total NMR assignments of new [C7-O-C7'']-biflavones from leaves of the limonene-carvone chemotype of Lippia alba (Mill) N. E. Brown.

PubMed

Barbosa, Francisco Geraldo; Lima, Mary Anne Sousa; Silveira, Edilberto Rocha

2005-04-01

Phytochemical analysis of leaves of the limonene-carvone chemotype of Lippia alba led to the isolation of two biflavonoids with a new structural pattern with an ether linkage: 5,5''-dihydroxy-6,4',6'',3''',4'''-pentamethoxy-[C(7)--O--C(7'')]-biflavone (1) and 4',4,5,5''-tetrahydroxy-6,6'',3'''-trimethoxy-[C(7)--O--C(7'')]-biflavone (2). Structural elucidation of the new compounds was established on the basis of spectral data, through the use of 1D NMR and several 2D shift correlated NMR pulse sequences (COSY, HMQC, HMBC and NOESY). Copyright (c) 2005 John Wiley & Sons, Ltd

Copper and manganese complexes based on 1,4-naphthalene dicarboxylic acid ligand and its derivative: Syntheses, crystal structures, and magnetic properties

NASA Astrophysics Data System (ADS)

Xing, Yubo; Liu, Yuqi; Xue, Xiaofei; Wang, Xinying; Li, Wei

2018-02-01

Three new metal-organic coordination polymers, {[Mn2(1,4-NDC)2 (C2H5OH) (DMF) (H2O)]·CH3OH}n(1), {[Mn(III)(1,4-NDC)(C2H5O)][Mn(II)(1,4-NDC)(DMF)(H2O)]}n(2) and {[Cu2(C13H9O4)4(H2O)2]}n(3) based on1,4-H2NDC and its derivative were hydrothermally synthesized (1,4-H2NDC = 1,4-naphthalene-dicarboxylic acid, C13H10O4 = 4-methyl formate-1-naphthalenecarboxylic acid), and characterized by techniques of single crystal X-ray diffraction, infrared spectra (IR), elemental analysis, powder X-ray diffraction(PXRD) and variable-temperature magnetic susceptibility measurements. X-ray crystal structure analyses reveal that complexes 1 and 2 show a same 3,5-connected fsc 3D topology network with the Schlȁfli symbol of {4·6·8}{4·66·83}. But, the valence of some Mn atom in complex 2 take place transition from the +II oxidation state to the +III oxidation state, which may be the effect of the different solvent ratio. In complex 3, the Cu⋯Cu distance of 2.620(13) Å is significantly shorter than the sum of the van der Waals radii of Cu (1.40 Å), resulting in a strong ferromagnetic interaction between the Cu(II) centers. Furthermore, the temperature-dependent magnetic susceptibility measurements exhibit overall antiferromagnetic interactions between manganese ions for complexes 1 and 2, and a strong ferromagnetic interaction between the Cu(II) centers for complex 3.

Electron impact ionisation cross section for organoplatinum compounds

NASA Astrophysics Data System (ADS)

Mahato, Dibyendu; Naghma, Rahla; Alam, Mohammad Jane; Ahmad, Shabbir; Antony, Bobby

2016-11-01

This article reports electron impact ionisation cross sections for platinum-based drugs viz., cisplatin (H6N2Cl2Pt), carboplatin (C6H12N2O4Pt), oxaliplatin (C8H14N2O4Pt), nedaplatin (C2H8N2O3Pt) and satraplatin (C10H22ClN2O4Pt) complexes used in the cancer chemotherapy. The multi-scattering centre spherical complex optical potential formalism is used to obtain the inelastic cross section for these large molecules upon electron impact. The ionisation cross section is derived from the inelastic cross section employing complex scattering potential-ionisation contribution method. Comparison is made with previous results, where ever available and overall a reasonable agreement is observed. This is the first attempt to report total ionisation cross sections for nedaplatin and satraplatin complexes.

Diisopropyl methylphosphonate (DIMP)

Integrated Risk Information System (IRIS)

Diisopropyl methylphosphonate ( DIMP ) ; CASRN 1445 - 75 - 6 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessmen

The hydrolysis of geminal ethers: a kinetic appraisal of orthoesters and ketals

PubMed Central

Repetto, Sonia L; Butts, Craig P; Lam, Joseph K W; Ratcliffe, Norman M

2016-01-01

Summary A novel approach to protecting jet fuel against the effects of water contamination is predicated upon the coupling of the rapid hydrolysis reactions of lipophilic cyclic geminal ethers, with the concomitant production of a hydrophilic acyclic hydroxyester with de-icing properties (Fuel Dehydrating Icing Inhibitors - FDII). To this end, a kinetic appraisal of the hydrolysis reactions of representative geminal ethers was undertaken using a convenient surrogate for the fuel–water interface (D2O/CD3CN 1:4). We present here a library of acyclic and five/six-membered cyclic geminal ethers arranged according to their hydroxonium catalytic coefficients for hydrolysis, providing for the first time a framework for the development of FDII. A combination of 1H NMR, labelling and computational studies was used to assess the effects that may govern the observed relative rates of hydrolyses. PMID:27559399

Energy Transfer between Post-Transition Elements & Rare Earths in Oxide & Chalcogenide Glasses.

DTIC Science & Technology

1979-08-27

Caird [13]. A calculation of reduced matrix elements of Pr3 in 20 Na O • 80 TeO2 glass [14] showed that they differ slightly from data of ref. [121... glasses Transition (lass 35 ZnO 65 TeO2 20 Na2 O 80 TeO 2 fX 106 fX 106 l.,eas 3a, a) Ia’l. faI f.me.s f al f+ I fal 3 H4 - 3 H6 1.56 1.65 1.12...Rare-Earth Doped Glasses 20. jIST HAEV CCnFn~m ,i cn,on ra e sideit If c."*Ar’ -- ~ 14-r by t?-h.c .: r Intensity parameters, radiative transition

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.

Flavonoids from Jovibarba globifera (Crassulaceae) rosette leaves and their antioxidant activity.

PubMed

Szewczyk, Katarzyna; Krzaczek, Tadeusz; Łopatyński, Tomasz; Gawlik-Dziki, Urszula; Zidorn, Christian

2014-01-01

Seven flavonoids new for the genus Jovibarba, kaempferol 1, kaempferol 3-O-galactopyranosyl-(1 → 2)-O-α-L-rhamnopyranoside 2, kaempferol 3-O-β-D-glucoside 3, kaempferol 3-O-α-L-rhamnopyranosyl-7-O-α-D-glucofuranosyl-(1 → 2)-O-α-L-rhamnopyranoside 4, kaempferol 3-O-β-D-glucopyranoside-7-O-α-L-rhamnopyranoside 5, kaempferol 3,7,4'-O-trimethyl ether 6 and quercetin 7, were isolated from fresh and dried leaves of J.ovibarba globifera subsp. globifera. The structures of these compounds were established by analysis of their spectroscopic ((1)H and (13)C NMR) and spectrometric (MS) data, as well as by comparison of these with those reported in the literature. All of the flavonoids are reported for the first time from the investigated taxon. In addition the antioxidant activities in DPPH test of selected compounds were evaluated.

Reductive deconstruction of organosolv lignin catalyzed by zeolite supported nickel nanoparticles

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

Kasakov, Stanislav; Shi, Hui; Camaioni, Donald M.

2015-11-01

Mechanistic aspects of deconstruction and hydrodeoxygenation of organosolv lignin using supported Ni catalysts with (Ni/HZSM-5 and Ni/HBEA) and without Brønsted acid sites (Ni/SiO2) are reported. Lignin was deconstructed and converted to saturated cyclic hydrocarbons ranging from C5 to C14. In the one-stage reaction, full conversion with total yield of 70 ± 5 wt.% saturated hydrocarbons was achieved at 593 K and 20 bar H2. The organosolv lignin used consists of seven to eight monolignol subunits and has an average molecular weight of ca. 1200 g mol-1. The monolignols were mainly guaiacyl, syringyl and phenylcoumaran, randomly interconnected through β-O-4, 4-O-5, β-1,more » 5-5’ and β-β ether bonds. In situ IR spectroscopy was used to follow the changes in lignin constituents during reaction. The proposed reaction pathways for the catalytic transformation of this organosolv lignin to alkanes start with the hydrogenolysis of aryl alkyl ether bonds, followed by hydrogenation of the aromatic compounds on Ni to cyclic alcohols. Oxygen is removed from the alcohols via dehydration on Brønsted acid sites to yield cyclic alkenes that are further hydrogenated to alkanes. Formation of condensation products may occur via intermolecular recombination of aromatic monomers or alkylation of aromatic compounds by alkenes. The financial support from TUM-PNNL cooperation project “Development of new methods for in situ characterization in liquid phase reactions” (CN-177939) is highly appreciated. The work by S.K., H.S., and J.A.L was partially supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences.« less

Platinum(0)-mediated C-O bond activation of ethers via an SN2 mechanism.

PubMed

Ortuño, Manuel A; Jasim, Nasarella A; Whitwood, Adrian C; Lledós, Agustí; Perutz, Robin N

2016-11-29

A computational study of the C(methyl)-O bond activation of fluorinated aryl methyl ethers by a platinum(0) complex Pt(PCyp 3 ) 2 (Cyp = cyclopentyl) (N. A. Jasim, R. N. Perutz, B. Procacci and A. C. Whitwood, Chem. Commun., 2014, 50, 3914) demonstrates that the reaction proceeds via an S N 2 mechanism. Nucleophilic attack of Pt(0) generates an ion pair consisting of a T-shaped platinum cation with an agostic interaction with a cyclopentyl group and a fluoroaryloxy anion. This ion-pair is converted to a 4-coordinate Pt(ii) product trans-[PtMe(OAr F )(PCyp 3 ) 2 ]. Structure-reactivity correlations are fully consistent with this mechanism. The Gibbs energy of activation is calculated to be substantially higher for aryl methyl ethers without fluorine substituents and higher still for alkyl methyl ethers. These conclusions are in accord with the experimental results. Further support was obtained in an experimental study of the reaction of Pt(PCy 3 ) 2 with 2,3,5,6-tetrafluoro-4-allyloxypyridine yielding the salt of the Pt(η 3 -allyl) cation and the tetrafluoropyridinolate anion [Pt(PCy 3 ) 2 (η 3 -allyl)][OC 5 NF 4 ]. The calculated activation energy for this reaction is significantly lower than that for fluorinated aryl methyl ethers.

Development of Dorzolamide Loaded 6-O-Carboxymethyl Chitosan Nanoparticles for Open Angle Glaucoma

PubMed Central

Ahmed, Mohammed Hadi

2013-01-01

Chitosan (CS) is a biodegradable, biocompatible, and mucoadhesive natural polymer soluble in acidic pH only and can be irritating to the eye. Objective of the study was to synthesize water soluble 6-O-carboxymethyl (OCM-CS) derivative of CS, and to develop CS and OCM-CS nanoparticles (NPs) loaded with dorzolamide hydrochloride (DRZ). CS was reacted with monochloroacetic acid (MCA) for OCM-CS synthesis and was characterized by FT-IR, DSC, and 13C NMR. CS and OCM-CS NPs were prepared by ionic gelation method. Ocular irritation potential were evaluated and therapeutic efficacy was measured by reduction in intraocular pressure (IOP) in normotensive rabbits. Maximum yield was obtained when the ratio of water/isopropyl alcohol was 1/4 at 55°C. The FT-IR, DSC and 13C NMR confirmed the formation of an ether linkage between hydroxyl groups of CS and MCA. The particle size and zeta potential of optimised CSNPs was 250.3 ± 2.62 nm and +33.47 ± 0.723 mV, whereas those for OCM-CSNPs were 187.1 ± 2.72 nm and 30.87 ± 0.86 mV. The entrapment efficiency was significantly improved for OCM-CSNPs, compared to CSNPs. OCM-CSNPs had tailored drug release and improved bioavailability with reduction in pulse entry as compared to CSNPs. Hence, it can be concluded that DRZ loaded OCM-CSNPs would be better alternative option to available eye drops for glaucoma treatment. PMID:24222858

Development of dorzolamide loaded 6-o-carboxymethyl chitosan nanoparticles for open angle glaucoma.

PubMed

Shinde, Ujwala; Ahmed, Mohammed Hadi; Singh, Kavita

2013-01-01

Chitosan (CS) is a biodegradable, biocompatible, and mucoadhesive natural polymer soluble in acidic pH only and can be irritating to the eye. Objective of the study was to synthesize water soluble 6-O-carboxymethyl (OCM-CS) derivative of CS, and to develop CS and OCM-CS nanoparticles (NPs) loaded with dorzolamide hydrochloride (DRZ). CS was reacted with monochloroacetic acid (MCA) for OCM-CS synthesis and was characterized by FT-IR, DSC, and (13)C NMR. CS and OCM-CS NPs were prepared by ionic gelation method. Ocular irritation potential were evaluated and therapeutic efficacy was measured by reduction in intraocular pressure (IOP) in normotensive rabbits. Maximum yield was obtained when the ratio of water/isopropyl alcohol was 1/4 at 55°C. The FT-IR, DSC and (13)C NMR confirmed the formation of an ether linkage between hydroxyl groups of CS and MCA. The particle size and zeta potential of optimised CSNPs was 250.3 ± 2.62 nm and +33.47 ± 0.723 mV, whereas those for OCM-CSNPs were 187.1 ± 2.72 nm and 30.87 ± 0.86 mV. The entrapment efficiency was significantly improved for OCM-CSNPs, compared to CSNPs. OCM-CSNPs had tailored drug release and improved bioavailability with reduction in pulse entry as compared to CSNPs. Hence, it can be concluded that DRZ loaded OCM-CSNPs would be better alternative option to available eye drops for glaucoma treatment.

Effects of blend of canola oil and palm oil on nutrient intake and digestibility, growth performance, rumen fermentation and fatty acids in goats.

PubMed

Adeyemi, Kazeem Dauda; Sazili, Awis Qurni; Ebrahimi, Mahdi; Samsudin, Anjas Asmara; Alimon, Abd Rasak; Karim, Roselina; Karsani, Saiful Anuar; Sabow, Azad Behnan

2016-09-01

The study examined the effects of blend of 80% canola oil and 20% palm oil (BCPO) on nutrient intake and digestibility, growth performance, rumen fermentation and fatty acids (FA) in goats. Twenty-four Boer bucks were randomly assigned to diets containing 0, 4 and 8% BCPO on a dry matter basis, fed for 100 days and slaughtered. Diet did not affect feed efficiency, growth performance, intake and digestibility of all nutrients except ether extract. Intakes and digestibilities of ether extract, unsaturated fatty acids (FA) and total FA were higher (P < 0.05) while digestibility of C18:0 was lower (P < 0.05) in oil-fed goats than the control goats. Total volatile FA, acetate, butyrate, acetate/propionate ratio and methane decreased (P < 0.05) with increasing BCPO but propionate, NH3 -N and rumen pH did not differ between diets. Ruminal concentration of C18:0, n-3 FA and total FA increased (P < 0.05) while C12:0, C14:0, C15:0 and n-6 FA decreased with increasing BCPO. Analysis of the FA composition of Triceps brachii muscle showed that concentrations of C16:0, C14:0 and C18:2n-6 were lower (P < 0.05) while C18:1n-9, C18:3n-3 and C20:5n-3 were higher in oil-fed goats compared with control goats. Dietary BCPO altered muscle lipids without having detrimental effects on nutrient intake and digestibility and growth performance in goats. © 2015 Japanese Society of Animal Science.

Bis-propargyl thermosets

DOEpatents

Douglas, Elliot P.; Langlois, David A.; Benicewicz, Brian C.

1995-01-01

The present invention provides (1) curable bispropargyl-containing monomers represented by the formula: B.sup.1 --A.sup.1.sub.m --R--A.sup.2.sub.n --B.sup.2 wherein R is a radical selected from the group consisting of 1,4-phenylene, 4,4'-biphenyl, 2,6-naphthalene, --C.sub.6 H.sub.4 --CR.sup.2 .dbd.CR.sup.2 --C.sub.6 H.sub.4 -- wherein R.sup.2 is H or CH.sub.3, and the same where said groups contain one or more substituents selected from the group consisting of halo, nitro, lower alkyl, lower alkoxy, fluoroalkyl or fluoroalkoxy, A.sup.1 and A.sup.2 are selected from the group consisting of --C.sub.6 H.sub.4 --C(O)--O-- and --C.sub.6 H.sub.4 --O--C(O)--, m and n are 0 or 1, m+n is 0, 1 or 2, and B.sup.1 and B.sup.2 are --OCH.sub.2 --C.tbd.C--H, (2) thermoset compositions comprised of cured segments derived from monomers represented by the formula: B.sup.1 --A.sup.1.sub.m --R--A.sup.2.sub.n --B.sup.2 as described above, and (3) curable blends of at least two of the monomers.

Heteroaryl ethers by oxidative palladium catalysis of pyridotriazol-1-yloxy pyrimidines with arylboronic acids.

PubMed

Bardhan, Sujata; Wacharasindhu, Sumrit; Wan, Zhao-Kui; Mansour, Tarek S

2009-06-18

The oxidative palladium-catalyzed cross-coupling of pyrimidines containing pyridotriazol-1-yloxy (OPt) as either a urea or an amide functional group with arylboronic acids in the presence of Cs(2)CO(3) in DME containing 0.6-1.0% H(2)O is described for the preparation of heteroaryl ethers. The bromo substitution in the case of 3-(5-bromo-pyrimidin-2-yloxy)-3H-[1,2,3]triazolo[4,5-b]pyridine 1 could serve as a handle for further elaborations such as Suzuki coupling for attaching varied aryl groups.

Isomorphous rare-earth bis[bis(2,6-diisopropylphenyl)phosphate] complexes and their self-assembly into two-dimensional frameworks by intramolecular hydrogen bonds.

PubMed

Minyaev, Mikhail E; Nifant'ev, Ilya E; Tavtorkin, Alexander N; Korchagina, Sof'ya A; Zeynalova, Shadana Sh; Ananyev, Ivan V; Churakov, Andrei V

2017-10-01

The crystal structures of rare-earth diaryl- or dialkylphosphate derivatives are poorly explored. Crystals of bis[bis(2,6-diisopropylphenyl)phosphato-κO]chloridotetrakis(methanol-κO)neodymium methanol disolvate, [Nd(C 24 H 34 O 4 P)Cl(CH 4 O) 4 ]·2CH 3 OH, (1), and of the lutetium, [Lu(C 24 H 34 O 4 P)Cl(CH 4 O) 4 ]·2CH 3 OH, (2), and yttrium, [Y(C 24 H 34 O 4 P)Cl(CH 4 O) 4 ]·2CH 3 OH, (3), analogues have been obtained by reactions between lithium bis(2,6-diisopropylphenyl)phosphate and LnCl 3 (H 2 O) 6 (in a 2:1 ratio) in methanol. Compounds (1)-(3) crystallize in the C2/c space group. Their crystal structures are isomorphous. The molecule possesses C 2 symmetry with a twofold crystallographic axis passing through the Ln and Cl atoms. The bis(2,6-diisopropylphenyl)phosphate ligands all display a κ 1 O-monodentate coordination mode. The coordination polyhedron for the metal atom [coordination number (CN) = 7] is a distorted pentagonal bipyramid. Each [Ln{O 2 P(O-2,6- i Pr 2 C 6 H 3 ) 2 } 2 Cl(CH 3 OH) 4 ] molecular unit exhibits two intramolecular O-H...O hydrogen bonds, forming six-membered rings, and two intramolecular O-H...Cl interactions, forming four-membered rings. Intermolecular O-H...O hydrogen bonds connect each unit via four noncoordinating methanol molecules with four other units, forming a two-dimensional hydrogen-bond network. Crystals of bis[bis(2,6-diisopropylphenyl)phosphato-κO]tetrakis(methanol-κO)(nitrato-κ 2 O,O')neodymium methanol disolvate, [Nd(C 24 H 34 O 4 P)(NO 3 )(CH 4 O) 4 ]·2CH 3 OH, (4), have been obtained in an analogous manner from NdCl 3 (H 2 O) 6 . Compound (4) also crystalizes in the C2/c space group. Its crystal structure is similar to those of (1)-(3). The κ 2 O,O'-bidentate nitrate anion is disordered over a twofold axis, being located nearly on it. Half of the molecule is crystallographically unique (CN Nd = 8). Unlike (1)-(3), complex (4) exhibits disorder of all three methanol molecules, one isopropyl group of the phosphate ligand and the NO 3 - ligand. The structure of (4) displays intra- and intermolecular O-H...O hydrogen bonds similar to those in (1)-(3). Compounds (1)-(4) represent the first reported mononuclear bis[bis(diaryl/dialkyl)phosphate] rare-earth complexes.

Birnessite-induced binding of phenolic monomers to soil humic substances and nature of the bound residues.

PubMed

Li, Chengliang; Zhang, Bin; Ertunc, Tanya; Schaeffer, Andreas; Ji, Rong

2012-08-21

The nature of the abiotic birnessite (δ-MnO(2))-catalyzed transformation products of phenolic compounds in the presence of soil organic matter is crucial for understanding the fate and stability of ubiquitous phenolic carbon in the environment. (14)C-radioactive and (13)C-stable-isotope tracers were used to study the mineralization and transformation by δ-MnO(2) of two typical humus and lignin phenolic monomers--catechol and p-coumaric acid--in the presence and absence of agricultural and forest soil humic acids (HAs) at pH 5-8. Mineralization decreased with increasing solution pH, and catechol was markedly more mineralized than p-coumaric acid. In the presence of HAs, the mineralization was strongly reduced, and considerable amounts of phenolic residues were bound to the HAs, independent of the solution pH. The HA-bound residues were homogeneously distributed within the humic molecules, and most still contained the unchanged aromatic ring as revealed by (13)C NMR analysis, indicating that the residues were probably bound via ester or ether bonds. The study provides important information on δ-MnO(2) stimulation of phenolic carbon binding to humic substances and the molecular distribution and chemical structure of the bound residues, which is essential for understanding the environmental fates of both naturally occurring and anthropogenic phenolic compounds.

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.

30 CFR 56.5006 - Restricted use of chemicals.

Code of Federal Regulations, 2011 CFR

2011-07-01

... recognized agency acceptable to the Secretary. (a) Carbon tetrachloride. (b) Phenol, (c) 4-Nitrobiphenyl, (d... Dichlorobenzidine, (h) Bis (chloromethyl) ether, (i) Beta-napthylamine, (j) Benzidine, (k) 4-Aminodiphenyl, (l) Ethyleneimine, (m) Beta-propiolactone, (n) 2-Acetylaminofluorene, (o) 4-Dimethylaminobenzene, and (p) N...

30 CFR 56.5006 - Restricted use of chemicals.

Code of Federal Regulations, 2010 CFR

2010-07-01

... recognized agency acceptable to the Secretary. (a) Carbon tetrachloride. (b) Phenol, (c) 4-Nitrobiphenyl, (d... Dichlorobenzidine, (h) Bis (chloromethyl) ether, (i) Beta-napthylamine, (j) Benzidine, (k) 4-Aminodiphenyl, (l) Ethyleneimine, (m) Beta-propiolactone, (n) 2-Acetylaminofluorene, (o) 4-Dimethylaminobenzene, and (p) N...

Crystal Structure and Magnetic Behavior of Two New Dinuclear Carbonato-Bridged Copper(II) Compounds. Superexchange Pathway for the Different Coordination Modes of the Carbonato Bridge in Polynuclear Copper(II) Compounds.

PubMed

Escuer, Albert; Mautner, Franz A.; Peñalba, Evaristo; Vicente, Ramon

1998-08-24

Four new &mgr;-CO(3)(2-) copper(II) complexes with different coordination modes for the carbonato bridge have been obtained by fixation of atmospheric CO(2): {(&mgr;(3)-CO(3))[Cu(3)(ClO(4))(3)(Et(3)dien)(3)]}(ClO(4)) (1), Et(3)dien = N,N',N"-triethylbis(2-aminoethane)amine; {(&mgr;-CO(3))[Cu(2)(H(2)O)(Et(4)dien)(2)]}(ClO(4))(2).H(2)O (2), Et(4)dien = N,N,N",N"-tetraethyl-bis(2-aminoethane)amine; {(&mgr;-CO(3))[Cu(2)(H(2)O)(2)(EtMe(4)dien)(2)]} (ClO(4))(2).2H(2)O (3), EtMe(4)dien = N'-ethyl-N,N,N",N"-tetramethylbis(2-aminoethane)amine; and {(&mgr;-CO(3))[Cu(2)(H(2)O)(Me(5)dien)(2)]}(ClO(4))(2).H(2)O (4), Me(5)dien = N,N,N',N",N"-pentamethylbis(2-aminoethane)amine. The crystal structures have been solved for 2, monoclinic system, space group P2(1)/n, formula [C(25)H(62)Cl(2)Cu(2)N(6)O(13)] with a = 12.763(6) Å, b = 25.125(8) Å, c = 13.261(4) Å, beta = 111.85(3) degrees, Z = 4, and for 3, triclinic system, space group P&onemacr;, formula [C(21)H(58)Cl(2)Cu(2)N(6)O(15)] with a = 8.412(3) Å, b = 14.667(4) Å, c = 16.555(5) Å, alpha = 99.66(2) degrees, beta = 102.14(2) degrees, gamma = 104.72(2) degrees, Z = 2. Susceptibility measurements show ferromagnetic behavior (J = +6.7(6) cm(-)(1)) for the trinuclear compound 1 whereas 2-4 are antiferromagnetically coupled with J = -17.8(8), -125.5(9), and -21.2(3) cm(-)(1) respectively. Certain synthetic aspects that may be related to the nuclearity of the copper(II) &mgr;-CO(3)(2-) compounds and the superexchange pathway for the different coordination modes of the carbonato bridge are discussed.

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

N-[2-(2,2-Di-methyl-propanamido)-pyrimidin-4-yl]-2,2-di-methyl-propanamide n-hexane 0.25-solvate hemihydrate.

PubMed

Ośmiałowski, Borys; Valkonen, Arto; Chęcińska, Lilianna

2013-10-05

The asymmetric unit of the title compound, C14H22N4O2·0.25C6H14·0.5H2O, contains two independent mol-ecules of 2,4-bis-(pivaloyl-amino)-pyrimidine (M) with similar conformations, one water mol-ecule and one-half n-hexane solvent mol-ecule situated on an inversion center. In one independent M mol-ecule, one of the two tert-butyl groups is rotationally disordered between two orientations in a 3:2 ratio. The n-hexane solvent mol-ecule is disordered between two conformations in the same ratio. The water mol-ecule bridges two independent M mol-ecules via O-H⋯O, N-H⋯O and O-H⋯N hydrogen bonds into a 2M·H2O unit, and these units are further linked by N-H⋯N hydrogen bonds into chains running in the [010] direction. Weak C-H⋯O inter-actions are observed between the adjacent chains.

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

Banerjee, Debasis; Borkowski, Lauren A.; Kim, Sun Jin

Two lithium-based metal-organic frameworks, Li{sub 2}(C{sub 14}H{sub 8}O{sub 4}) [Li{sub 2}(4,4'-BPDC) [1]; ULMOF-2, UL = ultralight; BPDC = biphenyldicarboxylate]; space group P2{sub 1}/c, a = 12.758(2) {angstrom}, b = 5.142(4) {angstrom}, c = 8.00(2) {angstrom}, {beta} = 97.23{sup o}, V = 520.6(14) {angstrom}{sup 3} and Li{sub 2}(C{sub 14}H{sub 8}O{sub 6}S) [Li{sub 2}(4,4'-SDB) [2]; ULMOF-3, UL = ultralight; SDB = sulfonyldibenzoate], space group P2{sub 1}/n, a = 5.5480(11) {angstrom}, b = 23.450(5) {angstrom}, c = 10.320(2) {angstrom}, {beta} = 96.47(3){sup o}, V = 1334.1(5) {angstrom}3, were synthesized. Compounds 1 and 2 were synthesized by solvothermal methods and were characterized using singlemore » crystal X-ray diffraction. Structure 1 consists of layers of two-dimensional antifluorite related LiO motif connected by BPDC linkers, whereas structure 2 is constructed by a combination of tetrameric lithium polyhedral clusters connected by the sulfonyldibenzoate linker. The frameworks are stable up to 575 and 500 C, respectively, under N{sub 2} atmosphere.« less

New Fluorinated Polymers

NASA Technical Reports Server (NTRS)

Fitch, John W., III

1997-01-01

This report summarizes progress during 1996 in our research effort along with a description of additional results associated with a TAG supplement to this grant (items 2 and 5 below). Progress is reported in five areas: 1) Polyamides Derived from [(p-HOOCC6H4)](sub 2)C(CF3)X (X= -CF3, OCH3, Cl); 2) Phosphorus-containing '12F-PEK' - Effect of Systematic Replacement of [(p-FC6H4COC6H4)](sub 2)C[(CF3)](sub 2) Monomer by [(p-FC6H4)](sub 2)(C6H5)PO; 3) Poly(ether ketone)s Derived from [(p-FC6H4COC6H4)](sub 2)(C6H5)PO; 4) New CF3-containing Organosilane Monomers and; 5) New Monomers for 12F-PEK Analogues with Improved Processability and Solubility.

High performance cobalt-free Cu1.4Mn1.6O4 spinel oxide as an intermediate temperature solid oxide fuel cell cathode

NASA Astrophysics Data System (ADS)

Zhen, Shuying; Sun, Wang; Li, Peiqian; Tang, Guangze; Rooney, David; Sun, Kening; Ma, Xinxin

2016-05-01

In this work Cu1.4Mn1.6O4 (CMO) spinel oxide is prepared and evaluated as a novel cobalt-free cathode for intermediate temperature solid oxide fuel cells (IT-SOFCs). Single phase CMO powder with cubic structure is identified using XRD. XPS results confirm that mixed Cu+/Cu2+ and Mn3+/Mn4+ couples exist in the CMO sample, and a maximum conductivity of 78 S cm-1 is achieved at 800 °C. Meanwhile, CMO oxide shows good thermal and chemical compatibility with a 10 mol% Sc2O3 stabilized ZrO2 (ScSZ) electrolyte material. Impedance spectroscopy measurements reveals that CMO exhibits a low polarization resistance of 0.143 Ω cm2 at 800 °C. Furthermore, a Ni-ScSZ/ScSZ/CMO single cell demonstrates a maximum power density of 1076 mW cm-2 at 800 °C under H2 (3% H2O) as the fuel and ambient air as the oxidant. These results indicate that Cu1.4Mn1.6O4 is a superior and promising cathode material for IT-SOFCs.

Computer Center Reference Manual

DTIC Science & Technology

1988-06-20

Compiler options, separated by colons (default: A-:B?-:BREG-8:BT-:C-:D+:H2:A H+24:L+:O+:P-:+:RV-:S4:S+4:A ST-:T+: TREG -8:U-:V+:A-:Z+) CPU- - Cray to execute...4 a 0~ 0 -. C 6 0 _ .0’ 63 r C 6 0 C .. 60 0 6 .- 6 ILC A L U 00 00 IL C 6 1 6j 0 1.- U 0 E L 14. E Lc C0 a 60. LL 1 0’. . 𔄀 - 66 6 0 DL C 6 a 4

Thermodesulfobacterium geofontis sp. nov., a hyperthermophilic, sulfate-reducing bacterium isolated from Obsidian Pool, Yellowstone National Park

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

Hamilton-Brehm, Scott D.; Gibson, Robert A.; Green, Stefan J.

2013-01-24

A novel sulfate-reducing bacterium designated OPF15T was isolated from Obsidian Pool, Yellowstone National Park, Wyoming. The phylogeny of 16S rRNA and functional genes (dsrAB) placed the organism within the family Thermodesulfobacteriaceae. The organism displayed hyperthermophilic temperature requirements for growth with a range of 70 90 C and an optimum of 83 C. Optimal pH was around 6.5 7.0 and the organism required the presence of H2 or formate as an electron donor and CO2 as a carbon source. Electron acceptors supporting growth included sulfate, thiosulfate, and elemental sulfur. Lactate, acetate, pyruvate, benzoate, oleic acid, and ethanol did not serve asmore » electron donors. Membrane lipid analysis revealed diacyl glycerols and acyl/ether glycerols which ranged from C14:0 to C20:0. Alkyl chains present in acyl/ether and diether glycerol lipids ranged from C16:0 to C18:0. Straight, iso- and anteiso-configurations were found for all lipid types. The presence of OPF15T was also shown to increase cellulose consumption during co-cultivation with Caldicellulosiruptor obsidiansis, a fermentative, cellulolytic extreme thermophile isolated from the same environment. On the basis of phylogenetic, phenotypic, and structural analyses, Thermodesulfobacterium geofontis sp. nov. is proposed as a new species with OPF15T representing the type strain.« less

Thermodesulfobacterium geofontis sp. nov., a hyperthermophilic, sulfate-reducing bacterium isolated from Obsidian Pool, Yellowstone National Park.

PubMed

Hamilton-Brehm, Scott D; Gibson, Robert A; Green, Stefan J; Hopmans, Ellen C; Schouten, Stefan; van der Meer, Marcel T J; Shields, John P; Damsté, Jaap S S; Elkins, James G

2013-03-01

A novel sulfate-reducing bacterium designated OPF15(T) was isolated from Obsidian Pool, Yellowstone National Park, Wyoming. The phylogeny of 16S rRNA and functional genes (dsrAB) placed the organism within the family Thermodesulfobacteriaceae. The organism displayed hyperthermophilic temperature requirements for growth with a range of 70-90 °C and an optimum of 83 °C. Optimal pH was around 6.5-7.0 and the organism required the presence of H2 or formate as an electron donor and CO2 as a carbon source. Electron acceptors supporting growth included sulfate, thiosulfate, and elemental sulfur. Lactate, acetate, pyruvate, benzoate, oleic acid, and ethanol did not serve as electron donors. Membrane lipid analysis revealed diacyl glycerols and acyl/ether glycerols which ranged from C14:0 to C20:0. Alkyl chains present in acyl/ether and diether glycerol lipids ranged from C16:0 to C18:0. Straight, iso- and anteiso-configurations were found for all lipid types. The presence of OPF15(T) was also shown to increase cellulose consumption during co-cultivation with Caldicellulosiruptor obsidiansis, a fermentative, cellulolytic extreme thermophile isolated from the same environment. On the basis of phylogenetic, phenotypic, and structural analyses, Thermodesulfobacterium geofontis sp. nov. is proposed as a new species with OPF15(T) representing the type strain.

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.

Synthesis,and structural characterization of [(CH3(C5H4N))Ga(SCH2(CO)O)]-[(4-MepyH)]+, a novel Ga(III) five coordinate complex.

NASA Technical Reports Server (NTRS)

Banger, Kulbinder K.; Duraj, Stan A.; Fanwic, Phillp E.; Hepp, Aloysius F.; Martuch, Robert A.

2003-01-01

The synthesis and structural characterization of a novel ionic Ga(III) five coordinate complex [{CH3(C5H4N)}Ga(SCH2(CO)O)2]-[(4-MepyH)]+, (4-Mepy = CH3(C5H5N)) from the reaction between Ga2Cl4 with sodium mercapto-acetic acid in 4-methylpyridine is described. Under basic reaction conditions the mercapto ligand is found to behave as a 2e- bidentate ligand. Single crystal X-ray diffraction studies show the complex to have a distorted square pyramidal geometry with the [(-SCH2(CO)CO-)] ligands in a trans conformation. The compound crystallizes in the P2(sub 1)/c (No. 14) space group with a = 7.7413(6) A, b = 16.744(2) A, c = 14.459(2) A, V = 1987.1(6) A(sup 3), R(F) = 0.032 and R(sub w) = 0.038.

Formation of polychlorinated diphenyl ethers from condensation of chlorophenols with chlorobenzenes.

PubMed

Liu, Wenxia; Zheng, Minghui; Liu, Wenbin; Ma, Xiaodong; Qian, Yong; Zhang, Bing

2008-01-01

Polychlorinated diphenyl ethers (PCDEs), which are among the members of persistent organic pollutants, and PCDEs have been determined in a number of environmental samples. The main possible sources are the technical production of chlorinated phenols and all processes of incomplete combustion. PCDEs were observed in the fly ash from a municipal waste incinerator (MWI). It was speculated that the condensation of chlorophenols with chlorobenzenes occurred via PCDEs to form polychlorinated dibenzofurans (PCDFs). Nevertheless, PCDEs formation from condensation of chlorophenols with chlorobenzenes has not been confirmed by experimental observation. The objective of this paper is to investigate the formation mechanism of PCDEs from the condensation of chlorophenols with chlorobenzenes. The results are expected to be helpful in understanding the formation of PCDEs and in controlling and abating PCDEs emissions from MWI. The pyrolysis of pentachlorophenol (PCP) and/or polychlorobenzenes (PCBz) was carried out in a sealed glass tube. The reaction products were extracted and purified with K2CO3 solution. The samples were concentrated and then cleaned up on an alumina column. GC/MS was used for identification and quantification of reaction products. The results showed that the pyrolysis of hexachlorobenzene (HCB) at 340 degrees C for 6 h led to the formation of decachlorodiphenyl ether (DCDE) (2.41 microg/mg) and octachlorodibenzo-p-dioxins (OCDD) (0.24 micropg/mg), while the pyrolysis of PCP yielded DCDE (13.08 microg/mg) and OCDD (180.13 microg/mg). In addition, the amount of DCDE formation from the pyrolysis of the mixture of PCP and HCB was 4.65 times higher than the total amount of DCDE formation from the pyrolysis of HCB and PCP, respectively. This indicated that PCP and HCB were prone to condensation and formation of DCDE. DCDE was the main congener of PCDEs from condensation of PCP with HCB at 340, 400 and 450 degrees C. A small amount of nonachlorodiphenyl ether (NCDE) was formed by dechlorination reaction at 450 degrees C. The condensation of PCP with 1,2,4,5-tetrachlorobenzene (Cl4Bz) formed 2,2',3,4,4',5,5',6-octachlorodiphenyl ether (OCDE). Small amounts of heptachlorodiphenyl ether (HpCDE) and hexachlorodiphenyl ether (HxCDE) were detected at 450 degrees C. Meanwhile, polychlorinated dibenzo-p-dioxins (PCDDs) and PCDFs were detected from the condensation of PCP and PCBz. Experimental studies clarified the behavior of the formation of PCDEs from condensation of polychlorophenols and PCBz. The condensation of polychlorophenols with PCBz formed PCDEs through elimination of HCl between polychlorophenols and PCBz molecules. Another pathway of PCDEs formation was elimination of H2O between two polychlorophenol molecules. In addition, dechlorination processes had caused the specific homologous pattern of PCDEs under higher temperatures.

Rotational Spectra of Halogenated Ethers Used as Volatile Anaesthetics

NASA Astrophysics Data System (ADS)

Vega-Toribio, Alicia; Lesarri, Alberto; Suenram, Richard D.; Grabow, Jens-Uwe

2009-06-01

Following previous microwave investigations by Suenram et al., we will report on the rotational spectrum of several halogenated ethers used as volatile anaesthetics, including sevoflurane ((CF_3)_2CH-O-CH_2F), isoflurane (CF_3CHCl-O-CHF_2), enflurane (CHFClCF_2-O-CHF_2) and methoxyflurane (CHCl_2CF_2-O-CH_3). This study has been conducted in the 6-18 GHz centimetre-wave region using Balle-Flygare-type FT-microwave spectroscopy. The results will include the analysis of the rotational spectra of minor species in natural abundance (^{13}C and ^{18}O in some cases), structural calculations and auxiliary ab initio modelling. The conformational and structural conclusions will be compared with previous gas-phase electron diffraction and solid-state X-ray diffraction analysis. R. D. Suenram, D. J. Brugh, F. J. Lovas and C. Chu, 51st OSU Int. Symp. On Mol. Spectrosc., Columbus, OH, 1999, RB07

Crystal structure of 1-meth-oxy-2,2,2-tris-(pyrazol-1-yl)ethane.

PubMed

Lyubartseva, Ganna; Parkin, Sean; Coleman, Morgan D; Mallik, Uma Prasad

2014-09-01

The title compound, C12H14N6O, consists of three pyrazole rings bound via nitro-gen to the distal ethane carbon of meth-oxy ethane. The dihedral angles between the three pyrazole rings are 67.62 (14), 73.74 (14), and 78.92 (12)°. In the crystal, mol-ecules are linked by bifurcated C-H,H⋯N hydrogen bonds, forming double-stranded chains along [001]. The chains are linked via C-H⋯O hydrogen bonds, forming a three-dimensional framework structure. The crystal was refined as a perfect (0.5:0.5) inversion twin.

Roles of Bridging Ligand Topology and Conformation in Controlling Exchange Interactions between Paramagnetic Molybdenum Fragments in Dinuclear and Trinuclear Complexes.

PubMed

Ung VÂ, V&acaron;n Ân; Cargill Thompson, Alexander M. W.; Bardwell, David A.; Gatteschi, Dante; Jeffery, John C.; McCleverty, Jon A.; Totti, Federico; Ward, Michael D.

1997-07-30

The magnetic properties of two series of dinuclear complexes, and one trinuclear complex, have been examined as a function of the bridging pathway between the metal centers. The first series of dinuclear complexes is [{Mo(V)(O)(Tp)Cl}(2)(&mgr;-OO)], where "OO" is [1,4-O(C(6)H(4))(n)O](2)(-) (n = 1, 1; n = 2, 3), [4,4'-O(C(6)H(3)-2-Me)(2)O](2)(-) (4), or [1,3-OC(6)H(4)O](2)(-) (2) [Tp = tris(3,5-dimethylpyrazolyl)hydroborate]. The second series of dinuclear complexes is [{Mo(I)(NO)(Tp)Cl}(2)(&mgr;-NN)], where "NN" is 4,4'-bipyridyl (5), 3,3'-dimethyl-4,4'-bipyridine (6), 3,8-phenanthroline (7), or 2,7-diazapyrene (8). The trinuclear complex is [{Mo(V)(O)(Tp)Cl}(3)(1,3,5-C(6)H(3)O(3))] (9), whose crystal structure was determined [9.5CH(2)Cl(2): C(56)H(81)B(3)Cl(13)Mo(3)N(18)O(6); monoclinic, P2(1)/n; a = 13.443, b = 41.46(2), c = 14.314(6) Å; beta = 93.21(3) degrees; V = 7995(5) Å(3); Z = 4; R(1) = 0.106]. In these complexes, the sign and magnitude of the exchange coupling constant J is clearly related to both the topology and the conformation of the bridging ligand [where J is derived from H = -JS(1)().S(2)() for 1-8 and H = -J(S(1)().S(2)() + S(2)().S(3)() + S(1)().S(3)()) for 9]. The values are as follows: 1, -80 cm(-)(1); 2, +9.8 cm(-)(1); 3, -13.2 cm(-)(1); 4, -2.8 cm(-)(1); 5, -33 cm(-)(1); 6, -3.5 cm(-)(1); 7, -35.6 cm(-)(1); 8, -35.0 cm(-)(1); 9, +14.4 cm(-)(1). In particular the following holds: (1) J is negative (antiferromagnetic exchange) across the para-substituted bridges ligands of 1 and 3-8 but positive (ferromagnetic exchange) across the meta-substituted bridging ligands of 2 and 9. (2) J decreases in magnitude dramatically as the bridging ligand conformation changes from planar to twisted (compare 3 and 4, or 6 and 8). These observations are consistent with a spin-polarization mechanism for the exchange interaction, propagated across the pi-system of the bridging ligand by via overlap of bridging ligand p(pi) orbitals with the d(pi) magnetic orbitals of the metals. The EPR spectrum of 9 is characteristic of a quartet species and shows weak Deltam(s) = 2 and Deltam(s) = 3 transitions at one-half and one-third, respectively, of the field strength of the principal Deltam(s) = 1 component.

Thermodynamic characterization of three polymorphic forms of piracetam.

PubMed

Picciochi, Ricardo; Diogo, Hermínio P; da Piedade, Manuel E Minas

2011-02-01

Combustion calorimetry, solution calorimetry, and differential scanning calorimetry (DSC) were used to determine the standard (p° = 0.1 MPa) molar enthalpies of formation of Forms I, II, and III piracetam at 298.15 K, namely, Δ(f) H(m)° (C(6)H(10)O(2)N(2), cr I) = -520.6 ± 1.6 kJ·mol(-1), Δ(f) H(m)° (C(6)H(10)O(2)N(2), cr II) = -523.8 ± 1.6 kJ·mol(-1), and Δ(f) H(m)° (C(6)H(10)O(2)N(2), cr III) = -524.1 ± 1.6 kJ·mol(-1). The enthalpy of formation of gaseous piracetam at 298.15 K was also derived as Δ(f) H(m)° (C(6)H(10)O(2)N(2), g) = -401.3 ± 2.1 kJ·mol(-1), by combining the standard molar enthalpy of formation of Form II piracetam with the corresponding enthalpy of sublimation, Δ(sub) H(m)° (C(6) H(10) O(2) N(2), cr II) = 122.5 ± 1.4 kJ·mol(-1), obtained by drop-sublimation Calvet microcalorimetry and the Knudsen effusion method. The Δ(f) H(m)° (C(6)H(10)O(2)N(2), g) value was used to assess the corresponding predictions by the B3LYP/cc-pVTZ (-335.3 kJ·mol(-1)), G3MP2 (-388.7 kJ·mol(-1)), and CBS-QB3 (-402.8 kJ·mol(-1)) methods, based on the calculation of the atomization enthalpy of piracetam. Finally, the results of the solution and DSC experiments indicate that the stability hierarchy of Forms I, II, and III piracetam at 298.15 K, for which there was conflicting evidence in the literature, is III > II > I. Copyright © 2010 Wiley-Liss, Inc.

New Apigenin Glycoside, Polyphenolic Constituents, Anti-inflammatory and Hepatoprotective Activities of Gaillardia grandiflora and Gaillardia pulchella Aerial Parts.

PubMed

Moharram, Fatma A; El Dib, Rabab Abd El Moneim; Marzouk, Mohamed S; El-Shenawy, Siham M; Ibrahim, Haitham A

2017-07-01

Gaillardia grandiflora Hort. ex Van Houte and Gaillardia pulchella Foug are flowering plants widely cultivated in Egypt for their ornamental value. Previous reports demonstrated that sesquiterpene derivatives represent the major compounds in both species. Moreover, only few flavones were identified from genus Gaillardia and few studies on the cytotoxicity of G. pulchella were found. Investigation of the phenolic constituents of the aerial parts of both species and evaluation of their anti-inflammatory and hepatoprotective activities. The 80% aqueous methanol extracts (AME) were prepared for both plants and evaluated for their biological activities. Phytochemical investigation of both extracts resulted in isolation of twelve compounds, which have been identified on the basis of ultraviolet, 1D and 2D nuclear magnetic resonance spectroscopy and negative ESI-MS. The new 8-hydroxyapigenin 6- O -β-D-apiofuranosyl-(1'''→6'')- C -β-D- 4 C 1 -glucopyranoside was isolated from G. grandiflora for the first time in nature, along with schaftoside, luteolin 6-C-β-D- 4 C 1 -glucopyranoside 8-methyl ether, apigenin 6- C -β-D- 4 C 1 -glucopyranoside 8-methyl ether, isoorientin, isovitexin, 6-methoxyluteolin and hispidulin, as well as vicenin-2, vitexin, luteolin and apigenin, which were isolated from G. pulchella together with 6-methoxyluteolin. Furthermore, the AME of both species were found to be nontoxic to mice and exhibited significant anti-inflammatory and hepatoprotective activities in dose dependent manner. Current results shed light on the phenolic constituents of G. grandiflora and G. pulchella aerial parts and the safety of the AME of both species, in addition to their significant anti-inflammatory and hepatoprotective activities. Both plant species may be promising candidates for natural anti-inflammatory and hepatoprotective drugs. Phytochemical investigation of Gaillardia grandiflora and Gaillardia pulchella 80% aqueous methanol extracts of the aerial parts led to the isolation of twelve compoundsThe new compound 8-hydroxyapigenin 6- O -β-D-apiofuranosyl-(1''''→6'')- C -β-D-4C1-glucopyranoside was isolated from G. grandiflora for the first time in natureSchaftoside, luteolin 6- C -β-D-4C1-glucopyranoside 8-methyl ether, apigenin 6- C -β-D-4C1-glucopyranoside 8-methyl ether, isoorientin, isovitexin, 6-methoxyluteolin and hispidulin were isolated from G. grandiflora Vicenin-2, vitexin, luteolin, apigenin and 6-methoxyluteolin were isolated from G. pulchella The extracts of both species were nontoxic to mice up to 5 g/kg body weightBoth extracts exhibited significant anti-inflammatory and hepatoprotective activities in dose dependent manner Abbreviations used: ALP: Alkaline phosphatase; ALT: Alanine aminotransferase; AME: The 80% aqueous methanol extract of G. grandiflora or G. pulchella aerial parts; AST: Aspartate aminotransferase; br d: Broad doublet; Comp-PC: Comparative paper chromatography; d: Doublet; 2D-PC: Two-dimensional paper chromatography; DMSO-d6: Deuterated dimethyl sulfoxide; G.: Gaillardia ; GPx: Glutathione peroxidase; GRd: Glutathione reductase; GSH: glutathione; GST: Glutathione-S-transferase; J : Nuclear spin-spin coupling constant; m: Multiplet; [M-H]-: Molecular ion peak; MDA: Malondialdehyde; m / z : Mass/charge ratio; NO: Nitric oxide; p: Probability; PC: Paper chromatography; Rf: Retention flow; rpm: Rotation per minute; s: Singlet; SDE: The ethanol extract of Scoparia dulcis ; SE: Standard error; SOD: Superoxide dismutase; TMS: Tetramethylsilane; λmax: Maximum fluorescence emission wavelength.

New Apigenin Glycoside, Polyphenolic Constituents, Anti-inflammatory and Hepatoprotective Activities of Gaillardia grandiflora and Gaillardia pulchella Aerial Parts

PubMed Central

Moharram, Fatma A.; El Dib, Rabab Abd El Moneim; Marzouk, Mohamed S.; El-Shenawy, Siham M.; Ibrahim, Haitham A.

2017-01-01

Background: Gaillardia grandiflora Hort. ex Van Houte and Gaillardia pulchella Foug are flowering plants widely cultivated in Egypt for their ornamental value. Previous reports demonstrated that sesquiterpene derivatives represent the major compounds in both species. Moreover, only few flavones were identified from genus Gaillardia and few studies on the cytotoxicity of G. pulchella were found. Aim of the Study: Investigation of the phenolic constituents of the aerial parts of both species and evaluation of their anti-inflammatory and hepatoprotective activities. Materials and Methods: The 80% aqueous methanol extracts (AME) were prepared for both plants and evaluated for their biological activities. Phytochemical investigation of both extracts resulted in isolation of twelve compounds, which have been identified on the basis of ultraviolet, 1D and 2D nuclear magnetic resonance spectroscopy and negative ESI-MS. Results: The new 8-hydroxyapigenin 6-O-β-D-apiofuranosyl-(1’’’→6’’)-C-β-D-4C1-glucopyranoside was isolated from G. grandiflora for the first time in nature, along with schaftoside, luteolin 6-C-β-D-4C1-glucopyranoside 8-methyl ether, apigenin 6-C-β-D-4C1-glucopyranoside 8-methyl ether, isoorientin, isovitexin, 6-methoxyluteolin and hispidulin, as well as vicenin-2, vitexin, luteolin and apigenin, which were isolated from G. pulchella together with 6-methoxyluteolin. Furthermore, the AME of both species were found to be nontoxic to mice and exhibited significant anti-inflammatory and hepatoprotective activities in dose dependent manner. Conclusion: Current results shed light on the phenolic constituents of G. grandiflora and G. pulchella aerial parts and the safety of the AME of both species, in addition to their significant anti-inflammatory and hepatoprotective activities. Both plant species may be promising candidates for natural anti-inflammatory and hepatoprotective drugs. SUMMARY Phytochemical investigation of Gaillardia grandiflora and Gaillardia pulchella 80% aqueous methanol extracts of the aerial parts led to the isolation of twelve compoundsThe new compound 8-hydroxyapigenin 6-O-β-D-apiofuranosyl-(1’’’’→6’’)-C-β-D-4C1-glucopyranoside was isolated from G. grandiflora for the first time in natureSchaftoside, luteolin 6-C-β-D-4C1-glucopyranoside 8-methyl ether, apigenin 6-C-β-D-4C1-glucopyranoside 8-methyl ether, isoorientin, isovitexin, 6-methoxyluteolin and hispidulin were isolated from G. grandifloraVicenin-2, vitexin, luteolin, apigenin and 6-methoxyluteolin were isolated from G. pulchellaThe extracts of both species were nontoxic to mice up to 5 g/kg body weightBoth extracts exhibited significant anti-inflammatory and hepatoprotective activities in dose dependent manner Abbreviations used: ALP: Alkaline phosphatase; ALT: Alanine aminotransferase; AME: The 80% aqueous methanol extract of G. grandiflora or G. pulchella aerial parts; AST: Aspartate aminotransferase; br d: Broad doublet; Comp-PC: Comparative paper chromatography; d: Doublet; 2D-PC: Two-dimensional paper chromatography; DMSO-d6: Deuterated dimethyl sulfoxide; G.: Gaillardia; GPx: Glutathione peroxidase; GRd: Glutathione reductase; GSH: glutathione; GST: Glutathione-S-transferase; J: Nuclear spin-spin coupling constant; m: Multiplet; [M-H]−: Molecular ion peak; MDA: Malondialdehyde; m/z: Mass/charge ratio; NO: Nitric oxide; p: Probability; PC: Paper chromatography; Rf: Retention flow; rpm: Rotation per minute; s: Singlet; SDE: The ethanol extract of Scoparia dulcis; SE: Standard error; SOD: Superoxide dismutase; TMS: Tetramethylsilane; λmax: Maximum fluorescence emission wavelength. PMID:28808387

Synthesis, structural characterization and density functional studies of ethyl 4-(biphenyl-4-yl)-2,6,6-trimethyl-5-oxo-1,4,5,6,7,8-hexahydroquinoline-3-carboxylate A non-merohedral twinned structure

NASA Astrophysics Data System (ADS)

Yıdırım, Sema Öztürk; Büyükmumcu, Zeki; Butcher, Ray J.; Çetin, Gökalp; Şimşek, Rahime; Şafak, Cihat

2018-07-01

1,4-Dihydropyridine (1,4-DHP) derivatives have the reducing effect of extracellular Ca2+ ions influx on the L-type calcium channel. Because of this effect many 1,4-DHP derivatives are potent calcium channel blockers and antihypertensive agents. The biphenyl group is present in the structures of the most biologically active compounds and thus is an important group. By introducing this moiety into the structure of various compounds, active compounds are obtained. Thus, pharmacologically active structures can be condensed with the biphenyl structure to achieve novel biologically active compounds or compounds with increased activity. In this study, to achieve an active calcium channel blocker compound, the biphenyl group was introduced into the 1,4-DHP structure. The structure of the compound is proved by IR, 1H NMR, Mass spectroscopy, X-ray crystallography and elemental analysis. The cytotoxic activity assays have continued and positive results have been obtained. The phenyl rings [C16-C21 and C22-C27] make dihedral angles of 84.4 (1) and 87.5 (1)°, respectively, with the 1,4-dihydropyridine ring [N1/C1/C4-C9]. In the crystal, adjacent molecules are linked by Nsbnd H … O and Csbnd H … O hydrogen bonds into chains parallel to [010].

Four-Coordinate Iron(II) Diaryl Compounds with Monodentate N-Heterocyclic Carbene Ligation: Synthesis, Characterization, and Their Tetrahedral-Square Planar Isomerization in Solution.

PubMed

Liu, Yuesheng; Luo, Lun; Xiao, Jie; Wang, Lei; Song, You; Qu, Jingping; Luo, Yi; Deng, Liang

2015-05-18

The salt elimination reactions of (IPr2Me2)2FeCl2 (IPr2Me2 = 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene) with the corresponding aryl Grignard reagents afford [(IPr2Me2)2FeAr2] (Ar = Ph, 3; C6H4-p-Me, 4; C6H4-p-(t)Bu, 5; C6H3-3,5-(CF3)2, 6) in good yields. X-ray crystallographic studies revealed the presence of both tetrahedral and trans square planar isomers for 3 and 6 and the tetrahedral structures for 4 and 5. Magnetic susceptibility and (57)Fe Mössbauer spectrum measurements on the solid samples indicated the high-spin (S = 2) and intermediate-spin (S = 1) nature of the tetrahedral and square planar structures, respectively. Solution property studies, including solution magnetic susceptibility measurement, variable-temperature (1)H and (19)F NMR, and absorption spectroscopy, on 3-6, as well as an (57)Fe Mössbauer spectrum study on a frozen tetrahydrofuran solution of tetrahedral [(IPr2Me2)2(57)FePh2] suggest the coexistence of tetrahedral and trans square planar structures in solution phase. Density functional theory calculations on (IPr2Me2)2FePh2 disclosed that the tetrahedral and trans square planar isomers are close in energy and that the geometry isomerization can occur by spin-change-coupled geometric transformation on four-coordinate iron(II) center.

Single-crystal X-ray diffraction and NMR crystallography of a 1:1 cocrystal of dithianon and pyrimethanil.

PubMed

Pöppler, Ann Christin; Corlett, Emily K; Pearce, Harriet; Seymour, Mark P; Reid, Matthew; Montgomery, Mark G; Brown, Steven P

2017-03-01

A single-crystal X-ray diffraction structure of a 1:1 cocrystal of two fungicides, namely dithianon (DI) and pyrimethanil (PM), is reported [systematic name: 5,10-dioxo-5H,10H-naphtho[2,3-b][1,4]dithiine-2,3-dicarbonitrile-4,6-dimethyl-N-phenylpyrimidin-2-amine (1/1), C 14 H 4 N 2 O 2 S 2 ·C 12 H 13 N 2 ]. Following an NMR crystallography approach, experimental solid-state magic angle spinning (MAS) NMR spectra are presented together with GIPAW (gauge-including projector augmented wave) calculations of NMR chemical shieldings. Specifically, experimental 1 H and 13 C chemical shifts are determined from two-dimensional 1 H- 13 C MAS NMR correlation spectra recorded with short and longer contact times so as to probe one-bond C-H connectivities and longer-range C...H proximities, whereas H...H proximities are identified in a 1 H double-quantum (DQ) MAS NMR spectrum. The performing of separate GIPAW calculations for the full periodic crystal structure and for isolated molecules allows the determination of the change in chemical shift upon going from an isolated molecule to the full crystal structure. For the 1 H NMR chemical shifts, changes of 3.6 and 2.0 ppm correspond to intermolecular N-H...O and C-H...O hydrogen bonding, while changes of -2.7 and -1.5 ppm are due to ring current effects associated with C-H...π interactions. Even though there is a close intermolecular S...O distance of 3.10 Å, it is of note that the molecule-to-crystal chemical shifts for the involved sulfur or oxygen nuclei are small.

Low severity coal conversion by ionic hydrogenation: Quarterly report, October--December 1988

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

Maioriello, J.; Larsen, J.W.

1988-12-31

A newly developed reaction system consisting of H/sub 2/O:BF/sub 3//H/sub 2//(CH/sub 3/CN)/sub 2/PtCl/sub 2/ was applied to the ionic hydrogenation of aromatic and functionalized aromatic compounds. Hydrogenations were carried out in this aqueous system at 50/degree/C and 500 psi H/sub 2/. Aryl ethers were hydrogenated and cleaved, yielding deoxygenated, fully saturated compounds as the major products. Reactions of nitrogen-containing aromatic compounds resulted in partial saturation of aromatic rings without cleavage of the C-N bonds. Aromatic and PNA compounds can be fully or partially hydrogenated depending on their structures. Aromatic thiols, sulfides and thiophenes poison the catalyst; the oxidized sulfur formsmore » (sulfonic acids, sulfones) were not reduced and did not poison the catalyst. It was found that certain aromatic compounds were easier to hydrogenate than others. Ionic hydrogenation of Wyodak cola using a H/sub 2/O:BF/sub 3//H/sub 2//(MeCN)/sub 2/PtCl/sub 2/ resulted in no significant increase in THF extractability (5.8--9.6% THF-extractables, wt) over that of the parent coal (4.6--6.7% THF-extractables, wt). Ionic hydrogenation of a demineralized Wyodak coal (1 M aq. citric acid, reflux 1 day) resulted in a slight increase in THF extractability (10.4%) over the untreated parent coal (5.6--5.8%). 4 refs., 1 fig., 1 tab.« less

[Chemical constituents from petroleum ether fraction of Swertia chirayita and their activities in vitro].

PubMed

You, Rong-Rong; Chen, Xue-Qing; He, Dan-Dan; Huang, Chang-Gao; Jin, Yang; Qian, Shi-Hui; Ju, Jian-Ming; Fan, Jun-Ting

2017-10-01

The present work is to study the chemical constituents from petroleum ether fraction of Tibetan medicine Swertia chirayita by column chromatography and recrystallization. The structures were identified by physical and chemical properties and spectral data as swerchirin (1), decussatin (2), 1,8-dihydroxy-3,5,7-trimethoxyxanthone (3), 1-hydroxy-3,5,7,8-tetramethoxyxanthone (4), bellidifolin (5), 1-hydroxy-3, 7-dimethoxyxanthone (6), methylswertianin (7), 1-hydroxy-3,5-dimethoxyxanthone (8), erythrodiol (9), oleanolic acid (10), gnetiolactone (11), scopoletin (12), sinapaldehyde (13), syringaldehyde (14), and β-sitosterol (15). Compounds 3, 4, 9, 11-14 were isolated from S. chirayita for the first time. Compounds 9 and 12 were firstly isolated from the genus Swertia. The cytotoxic activities of compounds 1, 2, 5, 7 and 8 against human pancreatic cancer cell lines SW1990 and BxPC-3,and the protective effects of these compounds against hydrogen peroxide (H2O2)-induced oxidative stress in human endothelium-derived EA.hy926 were investigated in vitro. The results showed no obvious effect at the high concentration of 50 μmol•L⁻¹. Copyright© by the Chinese Pharmaceutical Association.

Molecular structure and conformation of N-2-[3'-(methoxysalicylideneimino)benzyl]-3″-methoxysalicylideneimine

NASA Astrophysics Data System (ADS)

Dey, D. K.; Dey, S. P.; Elmali, A.; Elerman, Y.

2001-05-01

The Schiff base, N-2-[3'-(methoxysalicylideneimino)benzyl]-3″-methoxysalicylidene-imine, 1,2-C 6H 4[NCHC 6H 3(OMe-3')OH-2']CH 2NCHC 6H 3(OMe-3″)OH-2″, has been prepared by the reaction of 2-amino-1-benzylamine and 3-methoxysalicylaldehyde ( o-vanillin) in ethanol. The molecular structure has been confirmed by single crystal X-ray crystallography. The crystal is in the monoclinic space group P2 1/ n with a=16.179(5), b=6.715(5), c=18.780(6) Å, β=100.56(3)°, Dcalc=1.293 mg cm -3, V=2006(2) Å 3 and R=0.0357 for 3929 independent reflections. The 1H and 13C NMR spectra in CDCl 3 solution indicate the retention of solid state structure in solution. The title compound is not planar. Intramolecular hydrogen bonds occur between O(1) and N(1) [2.614(2) Å] and between O(2) and N(2) [2.585(2) Å] atoms, the hydrogen atom essentially being bonded to the oxygen atom. Minimum energy conformations from AM1 were calculated as a function of five torsion angles θ1 (C6-C7-N1-C8), θ2 (C14-N2-C15-C16), θ3 (C9-C8-N1-C7), θ4 (C13-C14-N2-C15) and θ5 (C10-C9-C8-N1), varied every 5°. The optimized geometry of the crystal structure corresponding to the non-planar conformation is the most stable conformation in all calculations. The results strongly indicate that the minimum energy conformation is primarily determined by non-bonded hydrogen-hydrogen repulsions.

μ-Hexa-thio-metadiphosphato-bis-[(1,4,7,10,13,16-hexa-oxa-cyclo-octa-decane-κ(6) O)rubidium] aceto-nitrile disolvate.

PubMed

Gjikaj, Mimoza; Pook, Niels-Patrick; Qarri, Flora

2013-12-01

The asymmetric unit of the title compound, [Rb2(P2S6)(C12H24O6)2]·2CH3CN, contains one half of an [Rb(18-crown-6)2]2[P2S6] unit and one aceto-nitrile solvent mol-ecule. The [Rb(18-crown-6)]2[P2S6] unit is completed by inversion symmetry. Its Rb(+) ion is situated near the centre of the macrocyclic cavity, but is displaced by 0.8972 (1) Å from the O atoms of the crown in the direction of the [P2S6](2-) moiety. The overall coordination number of the cation is eight, defined by the six crown ether O atoms and by two terminal S atoms of the [P2S6](2-) anion. The hexa-thio-metadiphosphate anion is built up from two tetra-hedral PS4 units joined together by a common edge. The crystal structure is characterized by alternating layers of [Rb(18-crown-6)]2[P2S6] and aceto-nitrile solvent mol-ecules stacked along [010].

Synthesis and crystal structure of a new 2,6-dimethyl piperazine-1,4-diium perchlorate monohydrate: [C{sub 6}H{sub 16}N{sub 2}](ClO{sub 4}){sub 2} · H{sub 2}O

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

Mleh, C. Ben; Roisnel, T.; Marouani, H., E-mail: houda.marouani@fsb.rnu.tn

2017-03-15

A proton transfer compound 2,6-dimethyl piperazine-1,4-diium perchlorate monohydrate was synthesized by slow evaporation at room temperature using 2,6-dimethyl piperazine as template. The asymmetric unit contains one organic dication, two crystal graphically independent perchlorate anions and one water molecule. Each organic entities is engaged in a large number of bifurcated and non-bifurcated N–H···O (O) and C–H···O hydrogen bonds with different species and enhanced the three dimensional supramolecular network. In addition, the diprotonated piperazine ring adopts a chair conformation with the methyl groups occupying equatorial positions.

Bonding Properties of a Novel Inorganometallic Complex, Ru(SnPh(3))(2)(CO)(2)(iPr-DAB) (iPr-DAB = N,N'-Diisopropyl-1,4-diaza-1,3-butadiene), and its Stable Radical-Anion, Studied by UV-Vis, IR, and EPR Spectroscopy, (Spectro-) Electrochemistry, and Density Functional Calculations.

PubMed

Aarnts, Maxim P.; Wilms, Maikel P.; Peelen, Karin; Fraanje, Jan; Goubitz, Kees; Hartl, Frantisek; Stufkens, Derk J.; Baerends, Evert Jan; Vlcek, Antonín

1996-09-11

Ru(SnPh(3))(2)(CO)(2)(iPr-DAB) was synthesized and characterized by UV-vis, IR, (1)H NMR, (13)C NMR, (119)Sn NMR, and mass (FAB(+)) spectroscopies and by single-crystal X-ray diffraction, which proved the presence of a nearly linear Sn-Ru-Sn unit. Crystals of Ru(SnPh(3))(2)(CO)(2)(iPr-DAB).3.5C(6)H(6) form in the triclinic space group P&onemacr; in a unit cell of dimensions a = 11.662(6) Å, b = 13.902(3) Å, c = 19.643(2) Å, alpha = 71.24(2) degrees, beta = 86.91(4) degrees, gamma = 77.89(3) degrees, and V = 2946(3) Å(3). One-electron reduction of Ru(SnPh(3))(2)(CO)(2)(iPr-DAB) produces the stable radical-anion [Ru(SnPh(3))(2)(CO)(2)(iPr-DAB)](*-) that was characterized by IR, and UV-vis spectroelectrochemistry. Its EPR spectrum shows a signal at g = 1.9960 with well resolved Sn, Ru, and iPr-DAB (H, N) hyperfine couplings. DFT-MO calculations on the model compound Ru(SnH(3))(2)(CO)(2)(H-DAB) reveal that the HOMO is mainly of sigma(Sn-Ru-Sn) character mixed strongly with the lowest pi orbital of the H-DAB ligand. The LUMO (SOMO in the reduced complex) should be viewed as predominantly pi(H-DAB) with an admixture of the sigma(Sn-Ru-Sn) orbital. Accordingly, the lowest-energy absorption band of the neutral species will mainly belong to the sigma(Sn-Ru-Sn)-->pi(iPr-DAB) charge transfer transition. The intrinsic strength of the Ru-Sn bond and the delocalized character of the three-center four-electron Sn-Ru-Sn sigma-bond account for the inherent stability of the radical anion.

Fenton-like Degradation of MTBE: Effects of Iron Counter Anion and Radical Scavengers

EPA Science Inventory

Fenton-driven oxidation of Methyl tert-butyl ether (MTBE) (0.11-0.16 mM) in batch reactors containing ferric iron (5 mM), hydrogen peroxide (H2O2) (6 mM) (pH=3) was performed to investigate MTBE transformation mechanisms. Independent variables included the form of iron (Fe) (Fe2(...

The effect of oxygen concentration on the boundary lubricating characteristics of an unformulated C-ether to 300 C

NASA Technical Reports Server (NTRS)

Jones, W. R., Jr.

1973-01-01

The effect of oxygen concentration on the boundary lubricating characteristics of an unformulated C-ether was studied with the use of a ball-on disk sliding-friction apparatus. Results were compared with those obtained with a polyphenyl ether. Experimental conditions included oxygen concentrations ranging from 20 percent (air) to 0.001 percent (nitrogen), a load of 1 kilogram, a sliding speed of 17 meters per minute, and disk temperatures ranging from 20 to 300 C (77 to 572 F). The C-ether yielded better boundary lubricating characteristics than did the polyphenyl ether in air and nitrogen over most of the temperature range. The C-ether exhibited lower wear at high oxygen levels (10 to 20 percent O2) from 25 to 200 C (77 to 392 F) and at low oxygen levels (0.001 to 1.0 percent O2) from 200 to 300 C (392 to 572 F). Friction polymer was observed around the wear scars of most test specimens. Friction polymer generation and its effect on wear are discussed in light of current theories.

Syntheses, structures, and physicochemical properties of diruthenium compounds of tetrachlorocatecholate with metal-metal bonded Ru(3+)(mu-OR)(2)Ru(3+) and Ru(3.5+)(mu-OR)(2)Ru(3.5+) cores (R = CH(3) and C(2)H(5)).

PubMed

Miyasaka, H; Chang, H C; Mochizuki, K; Kitagawa, S

2001-07-02

Metal-metal bonded Ru(3+)(mu-OR)(2)Ru(3+) and Ru(3.5+)(mu-OR)(2)Ru(3.5+) (R = CH(3) and CH(3)CH(2)) compounds with tetrachlorocatecholate (Cl(4)Cat) have been synthesized in the corresponding alcohol, MeOH and EtOH, from a nonbridged Ru(2+)-Ru(3+) compound, Na(3)[Ru(2)(Cl(4)Cat)(4)(THF)].3H(2)O.7THF (1). In alcohol solvents, compound 1 is continuously oxidized by oxygen to form Ru(3+)(mu-OR)(2)Ru(3+) and Ru(3.5+)(mu-OR)(2)Ru(3.5+) species. The presence of a characteristic countercation leads to selective isolation of either Ru(3+)(mu-OR)(2)Ru(3+) or Ru(3.5+)(mu-OR)(2)Ru(3.5+) as a stable adduct species. In methanol, Ph(4)PCl and dibenzo-18-crown-6-ether afford Ru(3+)(mu-OMe)(2)Ru(3+) species, [A](2)[Ru(2)(Cl(4)Cat)(4)(mu-OMe)(2)Na(2)(MeOH)(6)] ([A](+) = Ph(4)P(+) (2), [Na(dibenzo-18-crown-6)(H(2)O)(MeOH)](+) (3)), while benzo-15-crown-5-ether provides a Ru(3.5+)(mu-OMe)(2)Ru(3.5+) species, [Na(benzo-15-crown-5)(2)][Ru(2)(Cl(4)Cat)(4)(mu-OMe)(2)Na(2)(MeOH)(6)] (4). The air oxidation of 1 in a MeOH/EtOH mixed solvent (1:1 v/v) containing benzo-15-crown-5-ether provides a Ru(3.5+)(mu-OMe)(2)Ru(3.5+) species, [Na(benzo-15-crown-5)(H(2)O)][Ru(2)(Cl(4)Cat)(2)(mu-OMe)(2)Na(2)(EtOH)(2)(H(2)O)(2)(MeOH)(2)].(benzo-15-crown-5) (5). Similarly, the oxidation of 1 in ethanol with Ph(4)PCl provides a Ru(3.5+)(mu-OEt)(2)Ru(3.5+) species, (Ph(4)P)[Ru(2)(Cl(4)Cat)(4)(mu-OEt)(2)Na(2)(EtOH)(6)] (7). A selective formation of a Ru(3+)(mu-OEt)(2)Ru(3+) species, (Ph(4)P)(2)[Ru(2)(Cl(4)Cat)(4)(mu-OEt)(2)Na(2)(EtOH)(2)(H(2)O)(2)] (6), is found in the presence of pyrazine or 2,5-dimethylpyrazine. The crystal structures of these compounds, except 2 and 7, have been determined by X-ray crystallography, and all compounds have been characterized by several spectroscopic and magnetic investigations. The longer Ru-Ru bonds are found in the Ru(3+)(mu-OR)(2)Ru(3+) species (2.606(1) and 2.628(2) A for 3 and 6, respectively) compared with those of Ru(3.5+)(mu-OMe)(2)Ru(3.5+) species (2.5260(6) A and 2.514(2) A for 4 and 5, respectively). These structural features and magnetic and ESR data revealed the electronic configurations of sigma(2)pi(2)delta(2)delta(2)pi(2) and sigma(2)pi(2)delta(2)delta(2)pi(1) for Ru(3+)(mu-OR)(2)Ru(3+) and Ru(3.5+)(mu-OR)(2)Ru(3.5+), respectively, in which the former is diamagnetic and the latter is paramagnetic with S = (1)/(2) ground state. Compound 5 forms a one-dimensional chain with alternating arrangement of a Ru(3.5+)(mu-OMe)(2)Ru(3.5+) unit and a free benzo-15-crown-5-ether molecule by intermolecular hydrogen bonds (O(H(2)O).O(crown-ether) = 2.91-3.04 A). The cyclic voltammetry in DMF affords characteristic metal-origin voltammograms; two reversible and two quasi-reversible redox waves were observed. The feature of cyclic voltammograms for the Ru(3+)(mu-OR)(2)Ru(3+) species (2, 3, and 6) and the Ru(3.5+)(mu-OR)(2)Ru(3.5+) species (4 and 7) are similar to each other, indicating that both species are electrochemically stable. The isolation of the pyrazine-trans-coordinated species, [Ph(4)P][Ru(Cl(4)Cat)(2)(L)(2)] (L = pyrazine (8), 2,5-dimethylpyrazine (9)), revealed the selective isolation of 6 from pyrazine-containing solution. UV-vis spectral variation by ethanolysis for 9 demonstrated the selective conversion from the pyrazine-trans-coordinated species to the Ru(3+)(mu-OEt)(2)Ru(3+) species without an oxidation to the Ru(3.5+)(mu-OEt)(2)Ru(3.5+) species. This result suggests the presence of equilibrium between [Ru(Cl(4)Cat)(2)(L)(2)](-) and Ru(3+)(mu-OEt)(2)Ru(3+) species in the synthetic condition for 6.

Structure elucidation and chemical synthesis of stigmolone, a novel type of prokaryotic pheromone.

PubMed

Hull, W E; Berkessel, A; Plaga, W

1998-09-15

Approximately 2 micromol of a novel prokaryotic pheromone, involved in starvation-induced aggregation and formation of fruiting bodies by the myxobacterium Stigmatella aurantiaca, were isolated by a large-scale elution procedure. The pheromone was purified by HPLC, and high-resolution MS, IR, 1H-NMR, and 13C-NMR were used to identify the active substance as the hydroxy ketone 2,5, 8-trimethyl-8-hydroxy-nonan-4-one, which has been named stigmolone. The analysis was complicated by a solvent-dependent equilibrium between stigmolone and the cyclic enol-ether 3,4-dihydro-2,2, 5-trimethyl-6-(2-methylpropyl)-2H-pyran formed by intramolecular nucleophilic attack of the 8-OH group at the ketone C4 followed by loss of H2O. Both compounds were synthesized chemically, and their structures were confirmed by NMR analysis. Natural and synthetic stigmolone have the same biological activity at ca. 1 nM concentration.

The role of boric acid in the synthesis of Eni Carbon Silicates.

PubMed

Zanardi, Stefano; Bellussi, Giuseppe; Parker, Wallace O'Neil; Montanari, Erica; Bellettato, Michela; Cruciani, Giuseppe; Carati, Angela; Guidetti, Stefania; Rizzo, Caterina; Millini, Roberto

2014-07-21

The influence of H3BO3 on the crystallization of hybrid organic-inorganic aluminosilicates denoted as Eni Carbon Silicates (ECS's) was investigated. Syntheses were carried out at 100 °C under different experimental conditions, using bridged silsesquioxanes of general formula (EtO)3Si-R-Si(OEt)3 (R = -C6H4- (BTEB), -C10H6- (BTEN) and -C6H4-C6H4- (BTEBP)), in the presence of equimolar concentrations of NaAlO2 and H3BO3. The study, involving the synthesis of three different but structurally related phases (ECS-14 from BTEB, ECS-13 here described for the first time from BTEN, and ECS-5 from BTEBP), confirmed a catalytic role for H3BO3 which in general increased the crystallization rate and improved the product quality in terms of amount of crystallized phase (crystallinity), size of the crystallites and phase purity, while it was weakly incorporated in trace amounts in the framework of ECS's.

Information Management 70XX Civilian Equivalent

DTIC Science & Technology

1991-06-01

METHODOLOGY Data for this survey were collected using the USAF Job Inventory AFPT 90-70X-877 dated August 1989. Military specific or outdated tasks were...ce N: "!0 - 0- .4 x .V X 4 x .11 X I 4 N 10󈧎-14 aO M0I o % ci 4P W)-4 4z COZ 0 H ..J go w01 on Hu on I a I I I 1 6 M 100’’ CL. 0 A0C 0 u w .4 0 Z 1...4 -) 4)d) 0) ()0) 4)0() a) a) ) 0)0)w00 0 0 0 u H 0 4 4$ZP P-4 4P S 4W C0 CDH CD : lD )C 0 Cl 0 C \\Z t 00 00 -4 0000 0 00 D co C--1 C C14 -4 I - C14

N(4)-Methyl-N(4)-(2-methylphenyl)-1H-pyrazolo[3,4-d]pyrimidine-4,6-diamine-ethanol-hydrazine (1/0.865/0.135): hydrogen-bonded ribbons containing four independent ring types.

PubMed

Trilleras, Jorge; Quiroga, Jairo; Cobo, Justo; Glidewell, Christopher

2009-06-01

N(4)-Methyl-N(4)-(2-methylphenyl)-1H-pyrazolo[3,4-d]pyrimidine-4,6-diamine crystallizes from ethanol as a mixed solvate, C(13)H(14)N(6).0.865C(2)H(6)O.0.135N(2)H(4), (I), where the hydrazine has been carried through from the initial preparation. Within the heterocyclic component, the 2-methylphenyl substituent is disordered over two sets of sites. There is an intramolecular C-H...pi(arene) hydrogen bond, which may control the molecular conformation of the heterocycle. The heterocyclic molecules are linked by two independent N-H...N hydrogen bonds in a chain containing two types of R(2)(2)(8) ring. The ethanol component is linked to this chain by a combination of O-H...N and N-H...O hydrogen bonds and the hydrazine component by two N-H...N hydrogen bonds, so generating two R(3)(3)(9) rings and thus forming a ribbon containing four distinct ring types.

Genetic Exclusion in Bacteriophage T4.

DTIC Science & Technology

1987-01-01

1942) as "interference" between various coliphages , was shown by Delbruck and Bailey (1946) to be the inability of superinfecting phage to contribute... water : 5.8 g Na IPO , 3.0 2 4 g KH PO , 0.5 g NaCl, 1.0 g NH Cl, and the pH adjusted to 2 4 4 o 6.8 to 7.0. All media were autoclaved, cooled to 55 C...0.5M Tris), once with a 1:1 mixture of phenol and chloroform (1/24 isoamyl alcohol) then thrice iith an equal volume of water saturated ether. After

Tautomerism in o-hydroxyanilino-1,4-naphthoquinone derivatives: Structure, NMR, HPLC and density functional theoretic investigations

NASA Astrophysics Data System (ADS)

Bhand, Sujit; Patil, Rishikesh; Shinde, Yogesh; Lande, Dipali N.; Rao, Soniya S.; Kathawate, Laxmi; Gejji, Shridhar P.; Weyhermüller, Thomas; Salunke-Gawali, Sunita

2016-11-01

Structure and spectral characteristics of 'Ortho' ((E)-4-hydroxy-2-(2‧-(4‧-R)-hydroxyphenyl)-imino)-naphthalen-1(2H)-one) and 'para' (2-(2‧-(4‧-R)-hydroxyphenyl)-amino)-1,4-naphthoquinone) tautomers of o-hydroxyanilino-1,4-naphthoquinone derivatives (Rdbnd H, 1A; sbnd CH3, 2A; and -Cl, 3A) are investigated using the 1H, 13C, DEPT, gDQCOSY, gHSQCAD NMR, HPLC, cyclic voltammetry techniques combined with the density functional theory. The compound 2A crystallizes in monoclinic space group P21/c. wherein the polymer chain is facilitated via Osbnd H⋯O and Csbnd H⋯O intermolecular hydrogen bonding. Marginal variations in bond distances in quinonoid and aminophenol moieties render structural flexibility to these compounds those in solution exist as exist in 'ortho - para' tautomers. 1H and 13C NMR spectra in DMSO-d6 showed two sets of peaks in all compounds; whereas only the para tautomer of for 1A and 2A, the para tautomer is predominant in CD3CN solution. Further the ortho-para interconversion is accompanied by a large up-field signals for C(3)sbnd H(3) in their 1H and 13C NMR spectra. These inferences are corroborated by the density functional theoretic calculations.

3,6-Dimethyl-N 1,N 4-bis­(1-phenyl­eth­yl)-1,4-dihydro-1,2,4,5-tetra­zine-1,4-dicarboxamide

PubMed Central

Rao, Guo-Wu; Li, Qi; Lu, Xiao-Jing

2012-01-01

In the title mol­ecule, C22H26N6O2, the central tetra­zine ring exhibits a boat conformation, and the two phenyl rings form a dihedral angle of 88.39 (6)°. In the crystal, weak N—H⋯O and C—H⋯O hydrogen bonds link mol­ecules into layers parallel to the ab plane. PMID:22347041

Field Demonstration for P-D-680 Solvent Replacement (Part II)

DTIC Science & Technology

1998-05-12

jo \\ Ji o < s NJ £. ° 8? Q- 3* £?. «" «< o Ö- 8" 03 O C O ~ e O 3 re *i re re w8 g 3 2> 8 = er ^ o 3 ^ fS Ni O...34 3 3. 3. n_ £ 2. O 2- e. re Z. 2 3 v! 3 oso,o,<f)( ji «s S?3re-t930.Q3^. «o.03rt3-3c"o=; 1 » < 3 -•■n O -t33^c«^3ga3 re...soWfirtH T^ skd uiEita, ox^fifk^. 4. KrflTjTS, SAFETY 0? ALTERATIVE F-D-S80 SOLVENT Have you, cr did you have knowledge of ethers

Three Co(II) complexes with a sexidentate N2O4-donor bis-Schiff base ligand: Synthesis, crystal structures, DFT studies, urease inhibition and molecular docking studies

NASA Astrophysics Data System (ADS)

Wang, Hu; Zhang, Xia; Zhao, Yu; Zhang, Dongmei; Jin, Fan; Fan, Yuhua

2017-11-01

Three new N2O4-donor bis-Schiff base Co(II) complexes, Co(C36H34N2O8)·2CH3OH (1), Co(C28H34N2O8S2)·H2O (2) and Co(C40H36N4O8)·3CH3OH (3) with distorted octahedral six-coordinate Co(II) centers were synthesized and determined by single crystal X-ray analysis. The X-ray crystallography shows that the metal atoms of three complexes are all six-coordinate with two nitrogen atoms from Cdbnd N groups, two oxygen atoms from ether groups and two carboxylic oxygen atoms in the mono-ligand, forming a distorted octahedral geometry. Theoretical studies of the three complexes were carried out by density functional theory (DFT) Becke's three-parameter hybrid (B3LYP) method employing the 6-31G basis set. The DFT studies indicate that the calculation is in accordance with the experimental results. Moreover, inhibition of jack bean urease by Co(II) complexes 1-3 have also been investigated. At the same time, a docking analysis using a DOCK program was conducted to determine the probable binding mode by inserting the complexes into the active site of jack bean urease. The experimental values and docking simulation exhibited that the complex 3 showed strong inhibitory activity (IC50 = 16.43 ± 2.35 μM) and the structure-activity relationships were further discussed.

Gold(I) Complexes with N-Donor Ligands. 2.(1) Reactions of Ammonium Salts with [Au(acac-kappaC(2))(PR(3))] To Give [Au(NH(3))L](+), [(AuL)(2)(&mgr;(2)-NH(2))](+), [(AuL)(4)(&mgr;(4)-N)](+), or [(AuL)(3)(&mgr;(3)-O)](+). A New and Facile Synthesis of [Au(NH(3))(2)](+) Salts. Crystal Structure of [{AuP(C(6)H(4)OMe-4)(3)}(3)(&mgr;(3)-O)]CF(3)SO(3).

PubMed

Vicente, José; Chicote, María-Teresa; Guerrero, Rita; Jones, Peter G.; Ramírez De Arellano, M. Carmen

1997-09-24

The complexes [Au(acac-kappaC(2))(PR(3))] (acac = acetylacetonate, R = Ph, C(6)H(4)OMe-4) react with (NH(4))ClO(4) to give amminegold(I), [Au(NH(3))(PR(3))]ClO(4), amidogold(I), [(AuPR(3))(2)(&mgr;(2)-NH(2))]ClO(4), or nitridogold(I), [(AuPR(3))(4)(&mgr;(4)-N)]ClO(4), complexes, depending on the reaction conditions. Similarly, [Au(acac-kappaC(2))(PPh(3))] reacts with (NH(3)R')OTf (OTf = CF(3)SO(3)) (1:1) or with [H(3)N(CH(2))(2)NH(2)]OTf (1:1) to give (amine)gold(I) complexes [Au(NH(2)R')(PPh(3))]OTf (R' = Me, C(6)H(4)NO(2)-4) or [(AuPPh(3))(2){&mgr;(2)-H(2)N(CH(2))(2)NH(2)}](OTf)(2), respectively. The ammonium salts (NH(2)R'(2))OTf (R' = Et, Ph) react with [Au(acac-kappaC(2))(PR(3))] (R = Ph, C(6)H(4)OMe-4) (1:2) to give, after hydrolysis, the oxonium salts [(AuPR(3))(3)(&mgr;(3)-O)]OTf (R = Ph, C(6)H(4)OMe-4). When NH(3) is bubbled through a solution of [AuCl(tht)] (tht = tetrahydrothiophene), the complex [Au(NH(3))(2)]Cl precipitates. Addition of [Au(NH(3))(2)]Cl to a solution of AgClO(4) or TlOTf leads to the isolation of [Au(NH(3))(2)]ClO(4) or [Au(NH(3))(2)]OTf, respectively. The crystal structure of [(AuPR(3))(3)(&mgr;(3)-O)]OTf.Me(2)CO (R = C(6)H(4)OMe-4) has been determined: triclinic, space group P&onemacr;, a = 14.884(3) Å, b = 15.828(3) Å, c = 16.061(3) Å, alpha = 83.39(3) degrees, beta = 86.28(3) degrees, gamma = 65.54(3) degrees, R1 (wR2) = 0.0370 (0.0788). The [(AuPR(3))(3)(&mgr;(3)-O)](+) cation shows an essentially trigonal pyramidal array of three gold atoms and one oxygen atom with O-Au-P bond angles of ca. 175 degrees and Au.Au contacts in the range 2.9585(7)-3.0505(14) Å. These cations are linked into centrosymmetric dimers through two short Au.Au [2.9585(7), 3.0919(9) Å] contacts. The gold atoms of the dimer form a six-membered ring with a chair conformation.

Base-stabilized silaimine and its donor-free dimer derived from the reaction of NHC-supported silylene with SiCl4.

PubMed

Cui, Haiyan; Cui, Chunming

2015-12-21

Reaction of the N-heterocyclic carbene (NHC)-stabilized silylene ArN(SiMe3)Si(IiPr)Cl (1, Ar = 2,6-iPr2C6H3, IiPr = 1,3-diisopropyl-4,5-dimethyl-imidazol-2-ylidene) with SiCl4 resulted in the formation of three different products NHC-stabilized dichlorosilaimine ArN=Si(IiPr)Cl2 (2), aminotrichlorosilane ArN(SiMe3)SiCl3 (3) and a silaimine dimer (ArNSiCl2)2 (4) under different conditions. The products can be controlled by reaction conditions. Compound 2 is the first example of a less bulky NHC-supported silaimine via the reaction of a silylene with SiCl4.

Monochloro non-bridged half-metallocene-type zirconium complexes containing phosphine oxide-(thio)phenolate chelating ligands as efficient ethylene polymerization catalysts.

PubMed

Tang, Xiao-Yan; Wang, Yong-Xia; Liu, San-Rong; Liu, Jing-Yu; Li, Yue-Sheng

2013-01-14

A series of novel monochloro half-zirconocene complexes containing phosphine oxide-(thio)phenolate chelating ligands of the type, ClCp'Zr[X-2-R(1)-4-R(2)-6-(Ph(2)P=O)C(6)H(2)](2) (Cp' = C(5)H(5), 2a: X = O, R(1) = Ph, R(2) = H; 2b: X = O, R(1) = F, R(2) = H; 2c: X = O, R(1) = (t)Bu, R(2) = H; 2d: X = O, R(1) = R(2) = (t)Bu; 2e: X = O, R(1) = SiMe(3), R(2) = H; 2f: X = S, R(1) = SiMe(3), R(2) = H; Cp' = C(5)Me(5), 2g: X = O, R(1) = SiMe(3), R(2) = H), have been synthesized in high yields. These complexes were identified by (1)H {(13)C} NMR and elemental analyses. Structures for 2b, 2c and 2f were further confirmed by X-ray crystallography. Structural characterization of these complexes reveals crowded environments around the zirconium. Complexes 2b and 2c adopt six-coordinate, distorted octahedral geometry around the zirconium center, in which the equatorial positions are occupied by three oxygen atoms of two chelating phosphine oxide-bridged phenolate ligands and a chlorine atom. The cyclopentadienyl ring and one oxygen atom of the ligand are coordinated on the axial position. Complex 2f also folds a six-coordinate, distorted octahedral geometry around the Zr center, consisting of a Cp-Zr-O (in P=O) axis [177.16°] and a distorted plane of two sulfur atoms and one oxygen atom of two chelating phosphine oxide-bridged thiophenolate ligands as well as a chlorine atom. When activated by modified methylaluminoxane (MMAO), all the complexes exhibited high activities towards ethylene polymerization at high temperature (75 °C), giving high molecular weight polymers with unimodal molecular weight distribution. The formation of 14-electron, cationic metal alkyl species might come from the Zr-O (in phenol ring) bond cleavage based on the DFT calculations study.

A water-soluble and water-coordinated Mn(II) complex: synthesis, characterization and phantom MRI image study.

PubMed

Phukan, Bedika; Patel, Anant B; Mukherjee, Chandan

2015-08-07

Ligand H4bedik was reacted with MnCl2·4H2O at pH ∼ 6.5 to give a highly water-soluble and water-coordinated Mn(ii) complex (). The complex was found to show r1 = 3.11 mM(-1) s(-1) per Mn(ii) at 1.4 T and 6.26 mM(-1) s(-1) per Mn(ii) at 14.1 T at 25 °C, pH = 7.4. In addition to r1, the r2 at 14.1 T was found to be 132.78 mM(-1) s(-1) per Mn(ii) at 25 °C, pH = 7.4.

Ethers on Si(001): A Prime Example for the Common Ground between Surface Science and Molecular Organic Chemistry.

PubMed

Pecher, Lisa; Laref, Slimane; Raupach, Marc; Tonner, Ralf

2017-11-20

By using computational chemistry it has been shown that the adsorption of ether molecules on Si(001) under ultrahigh vacuum conditions can be understood with classical concepts of organic chemistry. Detailed analysis of the two-step reaction mechanism-1) formation of a dative bond between the ether oxygen atom and a Lewis acidic surface atom and 2) nucleophilic attack of a nearby Lewis basic surface atom-shows that it mirrors acid-catalyzed ether cleavage in solution. The O-Si dative bond is the strongest of its kind, and the reactivity in step 2 defies the Bell-Evans-Polanyi principle. Electron rearrangement during C-O bond cleavage has been visualized with a newly developed method for analyzing bonding, which shows that the mechanism of nucleophilic substitutions on semiconductor surfaces is identical to molecular S N 2 reactions. Our findings illustrate how surface science and molecular chemistry can mutually benefit from each other and unexpected insight can be gained. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Recharge of low-arsenic aquifers tapped by community wells in Araihazar, Bangladesh, inferred from environmental isotopes.

PubMed

Mihajlov, I; Stute, M; Schlosser, P; Mailloux, B J; Zheng, Y; Choudhury, I; Ahmed, K M; van Geen, A

2016-05-01

More than 100,000 community wells have been installed in the 150-300 m depth range throughout Bangladesh over the past decade to provide low-arsenic drinking water (<10 μg/L As), but little is known about how aquifers tapped by these wells are recharged. Within a 25 km 2 area of Bangladesh east of Dhaka, groundwater from 65 low-As wells in the 35-240 m depth range was sampled for tritium ( 3 H), oxygen and hydrogen isotopes of water ( 18 O/ 16 O and 2 H/ 1 H), carbon isotope ratios in dissolved inorganic carbon (DIC, 14 C/ 12 C and 13 C/ 12 C), noble gases, and a suite of dissolved constituents, including major cations, anions, and trace elements. At shallow depths (<90 m), 24 out of 42 wells contain detectable 3 H of up to 6 TU, indicating the presence of groundwater recharged within 60 years. Radiocarbon ( 14 C) ages in DIC range from modern to 10 kyr. In the 90-240 m depth range, however, only 5 wells shallower than 150 m contain detectable 3 H (<0.3 TU) and 14 C ages of DIC cluster around 10 kyr. The radiogenic helium ( 4 He) content in groundwater increases linearly across the entire range of 14 C ages at a rate of 2.5×10 -12 ccSTP 4 He g -1 yr -1 . Within the samples from depths >90 m, systematic relationships between 18 O/ 16 O, 2 H/ 1 H, 13 C/ 12 C and 14 C/ 12 C, and variations in noble gas temperatures, suggest that changes in monsoon intensity and vegetation cover occurred at the onset of the Holocene, when the sampled water was recharged. Thus, the deeper low-As aquifers remain relatively isolated from the shallow, high-As aquifer.

Recharge of low-arsenic aquifers tapped by community wells in Araihazar, Bangladesh, inferred from environmental isotopes

PubMed Central

Mihajlov, I.; Stute, M.; Schlosser, P.; Mailloux, B. J.; Zheng, Y.; Choudhury, I.; Ahmed, K.M.; van Geen, A.

2017-01-01

More than 100,000 community wells have been installed in the 150–300 m depth range throughout Bangladesh over the past decade to provide low-arsenic drinking water (<10 μg/L As), but little is known about how aquifers tapped by these wells are recharged. Within a 25 km2 area of Bangladesh east of Dhaka, groundwater from 65 low-As wells in the 35–240 m depth range was sampled for tritium (3H), oxygen and hydrogen isotopes of water (18O/16O and 2H/1H), carbon isotope ratios in dissolved inorganic carbon (DIC, 14C/12C and 13C/12C), noble gases, and a suite of dissolved constituents, including major cations, anions, and trace elements. At shallow depths (<90 m), 24 out of 42 wells contain detectable 3H of up to 6 TU, indicating the presence of groundwater recharged within 60 years. Radiocarbon (14C) ages in DIC range from modern to 10 kyr. In the 90–240 m depth range, however, only 5 wells shallower than 150 m contain detectable 3H (<0.3 TU) and 14C ages of DIC cluster around 10 kyr. The radiogenic helium (4He) content in groundwater increases linearly across the entire range of 14C ages at a rate of 2.5×10−12 ccSTP 4He g−1 yr−1. Within the samples from depths >90 m, systematic relationships between 18O/16O, 2H/1H, 13C/12C and 14C/12C, and variations in noble gas temperatures, suggest that changes in monsoon intensity and vegetation cover occurred at the onset of the Holocene, when the sampled water was recharged. Thus, the deeper low-As aquifers remain relatively isolated from the shallow, high-As aquifer. PMID:28966406

Organic Compounds Produced by Photolysis of Realistic Interstellar and Cometary Ice Analogs Containing Methanol

NASA Technical Reports Server (NTRS)

Bernstein, Max P.; Sandford, Scott A.; Allamandola, Louis J.; Chang, Sherwood; Scharberg, Maureen A.

1995-01-01

The InfraRed (IR) spectra of UltraViolet (UV) and thermally processed, methanol-containing interstellar / cometary ice analogs at temperatures from 12 to 300 K are presented. Infrared spectroscopy, H-1 and C-13 Nuclear Magnetic Resonance (NMR) spectroscopy, and gas chromatography-mass spectrometry indicate that CO (carbon monoxide), CO2 (carbon dioxide), CH4 (methane), HCO (the formyl radical), H2CO (formaldehyde), CH3CH2OH (ethanol), HC([double bond]O)NH2 (formamide), CH3C([double bond]O)NH2 (acetamide), and R[single bond]C[triple bond]N (nitriles) are formed. In addition, the organic materials remaining after photolyzed ice analogs have been warmed to room temperature contain (in rough order of decreasing abundance), (1) hexamethylenetetramine (HMT, C6H12N4), (2) ethers, alcohols, and compounds related to PolyOxyMethylene (POM, ([single bond]CH2O[single bond](sub n)), and (3) ketones (R[single bond]C([double bond]O)[single bond]R') and amides (H2NC([double bond]O)[single bond]R). Most of the carbon in these residues is thought to come from the methanol in the original ice. Deuterium and C-13 isotopic labeling demonstrates that methanol is definitely the source of carbon in HMT. High concentrations of HMT in interstellar and cometary ices could have important astrophysical consequences. The ultraviolet photolysis of HMT frozen in H2O ice readily produces the 'XCN' band observed in the spectra of protostellar objects and laboratory ices, as well as other nitriles. Thus, HMT may be a precursor of XCN and a source of CN in comets and the interstellar medium. Also, HMT is known to hydrolyze under acidic conditions to yield ammonia, formaldehyde, and amino acids. Thus, HMT may be a significant source of prebiogenic compounds on asteroidal parent bodies. A potential mechanism for the radiative formation of HMT in cosmic ices is outlined.

The fungal phytotoxin alternariol 9-methyl ether and some of its synthetic analogues inhibit the photosynthetic electron transport chain.

PubMed

Demuner, Antonio Jacinto; Barbosa, Luiz Cláudio Almeida; Miranda, Ana Cristina Mendes; Geraldo, Guilherme Carvalho; da Silva, Cleiton Moreira; Giberti, Samuele; Bertazzini, Michele; Forlani, Giuseppe

2013-12-27

Alternariol and monomethylalternariol are natural phytotoxins produced by some fungal strains, such as Nimbya and Alternaria. These substances confer virulence to phytopathogens, yet no information is available concerning their mode of action. Here we show that in the micromolar range alternariol 9-methyl ether is able to inhibit the electron transport chain (IC50 = 29.1 ± 6.5 μM) in isolated spinach chloroplasts. Since its effectiveness is limited by poor solubility in water, several alternariol analogues were synthesized using different aromatic aldehydes. The synthesized 6H-benzo[c]cromen-6-ones, 5H-chromene[4,3-b]pyridin-5-one, and 5H-chromene[4,3-c]pyridin-5-one also showed inhibitory properties, and three 6H-benzo[c]cromen-6-ones were more effective (IC50 = 12.8-22.8 μM) than the lead compound. Their addition to the culture medium of a cyanobacterial model strain was found to inhibit algal growth, with a relative effectiveness that was consistent with their activity in vitro. In contrast, the growth of a nonphotosynthetic plant cell culture was poorly affected. These compounds may represent a novel lead for the development of new active principles targeting photosynthesis.

Metal-organic frameworks assembled from lanthanide and 2,5-pyridinedicaboxylate with cubane-like [Ln4(OH)4] building units

NASA Astrophysics Data System (ADS)

Abdelbaky, Mohammed S. M.; Amghouz, Zakariae; Fernández-Zapico, Eva; García-Granda, Santiago; García, José R.

2015-09-01

Lanthanide-organic frameworks based on 2,5-pyridinedicaboxylate (25p) ligand, formulated as [Yb4(OH)4(25p)4(H2O)3]·H2O (25pYb), [Y4(OH)4(25p)4(H2O)3]·H2O (25pY-1) and [Y6(OH)8(25p)5(H2O)2] (25pY-2), have been obtained as single phases under hydrothermal conditions. 25pYb and 25pY-1 are isostructural, and crystallize in the triclinic space group, P-1, with a=8.6075(5) Å, b=14.8478(7) Å, c=15.9164(9) Å, α=86.277(4)°, β=80.196(5)°, γ=81.785(4)°, and a=8.7166(6) Å, b=14.966(1) Å, c=15.966(1) Å, α=86.260(6)°, β=80.036(6)°, γ=81.599(6)°, respectively. 25pY-2 crystallizes in the monoclinic space group, P21/c, with a=24.9117(17) Å, b=13.7340(8) Å, c=14.3385(10) Å, β=100.551(7)°. 25pYb and 25pY-2 have been structurally characterized by single-crystal X-ray diffraction. The 25pYb structure is based on tetranuclear cubane-like [Yb4(OH)4]8+ clusters, which are interconnected to eight neighbouring clusters through teen surrounding 25p ligands leading to neutral 3D framework, while the structure of 25pY-2 is based on two independent cuban-like [Y4(OH)4]8+ clusters, which are joined together through Y1 cation leading to the formation of hexanuclear [Y6(OH)8]10+ clusters, which in turn are joined via Y2 cation resulting in infinite inorganic chain extending along c-axis, and each chain is interconnected to six adjacent chains through 25p ligands leading finally to 3D framework. The luminescence properties of Eu3+ and Tb3+ doped 25pY-1 and 25pY-2 compounds have also been investigated. All materials has been characterized by powder X-ray diffraction, thermal analyses (TG-SDTA-MS), FTIR spectroscopy, C-H-N elemental analysis, scanning electron microscopy (SEM-EDX), and powder X-ray thermodiffraction.

Benzene-1,4-diol–5-(1H-imidazol-1-yl)pyrimidine (1/1)

PubMed Central

Jiang, Yan-Ke; Hou, Gui-Ge

2011-01-01

The asymmetric unit of title compound, C7H6N4·C6H6O2, contains one 5-(1H-imidazol-1-yl)pyrimidine mol­ecule and two half benzene-1,4-diol mol­ecules; the benzene-1,4-diol mol­ecules are located on individual inversion centers. In the pyrimidine mol­ecule, the imidazole ring is twisted with respect to the pyrimidine ring at a dihedral angle of 25.73 (7)°. In the crystal, O—H⋯N hydrogen bonds link the mol­ecules to form supra­molecular chains. π–π stacking is also observed in the crystal, the centroid–centroid distance between parallel imdazole rings being 3.5543 (16) Å. PMID:22220081

Design and syntheses of hybrid metal–organic materials based on K{sub 3}[M(C{sub 2}O{sub 4}){sub 3}]·3H{sub 2}O [M(III)=Fe, Al, Cr] metallotectons

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

Sun, Yayong; Zong, Yingxia; Ma, Haoran

2016-05-15

By using K{sub 3}[M(C{sub 2}O{sub 4}){sub 3}]·3H{sub 2}O [M(III)=Fe, Al, Cr] (C{sub 2}O{sub 4}{sup 2−}=oxalate) metallotectons as the starting material, we have synthesized eight novel complexes with formulas [{Fe(C_2O_4)_2(H_2O)_2}{sub 2}]·(H–L{sub 1}){sub 2}·H{sub 2}O 1, [Fe(C{sub 2}O{sub 4})Cl{sub 2}]·(H{sub 2}–L{sub 2}){sub 0.5}·(L{sub 2}){sub 0.5}·H{sub 2}O 2, [{Fe(C_2O_4)_1_._5Cl_2}{sub 2}]·(H–L{sub 3}){sub 4}3, [Fe{sub 2}(C{sub 2}O{sub 4})Cl{sub 8}]·(H{sub 2}–L{sub 4}){sub 2}·2H{sub 2}O 4, K[Al(C{sub 2}O{sub 4}){sub 3}]·(H{sub 2}–L{sub 5})·2H{sub 2}O 5, K[Al(C{sub 2}O{sub 4}){sub 3}]·(H–L{sub 6}){sub 2}·2H{sub 2}O 6, K[Cr(C{sub 2}O{sub 4}){sub 3}]·2H{sub 2}O 7, Na[Fe(C{sub 2}O{sub 4}){sub 3}]·(H–L{sub 6}){sub 2}·2H{sub 2}O 8 (with L{sub 1}=4-dimethylaminopyridine, L{sub 2}=2,3,5,6-tetramethylpyrazine, L{sub 3}=2-aminobenzimidazole, L{sub 4}=1,4-bis-(1H-imidazol-1-yl)benzene, L{sub 5}=1,4-bis((2-methylimidazol-1-yl)methyl)benzene,more » L{sub 6}=2-methylbenzimidazole). Their structures have been determined by single-crystal X-ray diffraction analyses, elemental analyses, IR spectra and thermogravimetric analyses. Compound 3 is a 2D H-bonded supramolecular architecture. Others are 3D supramolecular structures. Compound 1 shows a [Fe(C{sub 2}O{sub 4}){sub 2}(H{sub 2}O){sub 2}]{sup −} unit and 3D antionic H-bonded framework. Compound 2 features a [Fe(C{sub 2}O{sub 4})Cl{sub 2}]{sup -} anion and 1D iron-oxalate-iron chain. Compound 3 features a [Fe{sub 2}(C{sub 2}O{sub 4}){sub 3}Cl{sub 4}]{sup 4−} unit. Compound 4 features distinct [Fe{sub 2}(C{sub 2}O{sub 4})Cl{sub 8}]{sup 4−} units, which are mutual linked by water molecules to generated a 2D H-bonded network. Compound 5 features infinite ladder-like chains constructed by [Al(C{sub 2}O{sub 4}){sub 3}]{sup 3−} units and K{sup +} cations. The 1D chains are further extended into 3D antionic H-bonded framework through O–H···O H-bonds. Compounds 6–8 show 2D [KAl(C{sub 2}O{sub 4}){sub 3}]{sup 2−} layer, [KCr(C{sub 2}O{sub 4}){sub 3}]{sup 2−} layer and [NaFe(C{sub 2}O{sub 4}){sub 3}]{sup 2−} layer, respectively. - Graphical abstract: We report here eight novel complexes by using [M(C{sub 2}O{sub 4}){sub 3}]{sup 3−} [M(III)=Fe, Al, Cr] metallotectons as the starting materials. These complexes show supramolecular architectures bonded by charge-assisted hydrogen bonds.« less

Identification and characterization of dimeric oxidation products of p-cymene-2,3-diol isolated from Thymus vulgaris L.

PubMed

Rainis, Guido; Ternes, Waldemar

2014-01-08

The aim of this study was to investigate the oxidation products of p-cymene-2,3-diol, a major antioxidative constituent of thyme (Thymus vulgaris L.). Although a dimeric form of p-cymene-2,3-diol and some derivative substances exhibiting valuable food technological and health-promoting properties have been reported in earlier publications, no obvious correlation has been shown between these substances. A modified HPLC-ESI-MS method made it possible to prove that two dimers, 3,4,3',4'-tetrahydroxy-5,5'-diisopropyl-2,2'-dimethylbiphenyl (1) and the newly identified 3',4'-dihydroxy-5,5'-diisopropyl-2,2'-dimethylbiphenyl-3,4-dione (2), are oxidation products of p-cymene-2,3-diol. 2 was characterized by the fragmentation pattern determined by multiple mass spectrometry, (1)H NMR, (13)C NMR, H-H COSY, HSQC, and HMBC. Both biphenyls were also quantitated in freeze-dried thyme as well as in a food matrix spiked with thyme extract. Model experiments using raw and cooked minced pork meat as matrix and sodium nitrite as oxidizing and reduction agent with and without ascorbic acid as protective reagent showed the correlation between food processing and dimer generation.

Conformational Preference and Donor Atom Interaction Leading to Hexacoordination vs Pentacoordination in Bicyclic Tetraoxyphosphoranes(1).

PubMed

Sherlock, David J.; Chandrasekaran, A.; Prakasha, T. K.; Day, Roberta O.; Holmes, Robert R.

1998-01-12

New bicyclic tetraoxyphosphoranes all containing a six-membered oxaphosphorinane ring, C(6)H(8)(CH(2)O)(2)P(OC(12)H(8))(OXyl) (1), (C(6)H(4)O)(2)P(OC(12)H(8))(OXyl) (2), CH(2)[(t-Bu)(2)C(6)H(2)O](2)P(OC(12)H(8))(OXyl) (3), O(2)S[(t-Bu)MeC(6)H(2)O](2)P(OC(12)H(8))(OXyl) (4), and S[(t-Bu)MeC(6)H(2)O](2)P(OC(12)H(8))(OXyl) (5), were synthesized by the oxidative addition reaction of the cyclic phosphine P(OC(12)H(8))(OXyl) (6) with an appropriate diol in the presence of N-chlorodiisopropylamine. X-ray analysis revealed trigonal bipyramidal (TBP) geometries for 1-4 where the dioxa ring varied in size from six- to eight-membered. With a sulfur donor atom as part of an eight-membered ring in place of a potential oxygen donor atom of a sulfone group as in 4, the X-ray study of 5 showed the formation of a hexacoordinated structure via a P-S interaction. Ring constraints are evaluated to give an order of conformational flexibility associated with the (TBP) tetraoxyphosphoranes 4 > 3 approximately 1 > 2 which parallels the degree of shielding from (31)P NMR chemical shifts: 4 > 3 > 1 > 2. The six- and seven-membered dioxa rings in 1 and 2, respectively, are positioned at axial-equatorial sites, whereas the eight-membered dioxa ring in 3 and 4 occupies diequatorial sites of a TBP. V-T (1)H NMR data give barriers to xylyl group rotation about the C-OXyl bond. The geometry of 5 is located along a coordinate from square pyramidal toward octahedral to the extent of 60.7%. Achieving hexacoordination in bicyclic tetraoxyphosphoranes of reduced electrophilicity relative to bicyclic pentaoxyphosphoranes appears to be dependent on the presence of a sufficiently strong donor atom.

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

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.

Discovery and Role of a Novel Eicosanoid Family in Breast Cancer

DTIC Science & Technology

2009-08-01

electron impact mode (70 eV) using a Thermo Finnigan Trace DSQ instrument equipped with a 30 m HP5 column (0.25 mm i.d., film thickness 0.25 µm). The...TMS ether derivative was prepared. The electron impact analysis (70 eV) of the syn and anti isomers gave essentially the same mass spectra with major...cis,trans-dienes (H7: δ 6.57 ppm, dd, J = 15.1 Hz/11.0 Hz; H8: δ 6.13, dd, J = 11.0; H6: δ 5.70, dd, J = 14.9 Hz/6.3 Hz, H9: δ 5.55, m; and H13 : δ 6.51

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

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.

Syntheses, structures, and vibrational spectroscopy of the two-dimensional iodates Ln(IO{sub 3}){sub 3} and Ln(IO{sub 3}){sub 3}(H{sub 2}O) (Ln =Yb, Lu)

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

Assefa, Zerihun; Ling Jie; Haire, Richard G.

2006-12-15

The reaction of Lu{sup 3+} or Yb{sup 3+} and H{sub 5}IO{sub 6} in aqueous media at 180 {sup o}C leads to the formation of Yb(IO{sub 3}){sub 3}(H{sub 2}O) or Lu(IO{sub 3}){sub 3}(H{sub 2}O), respectively, while the reaction of Yb metal with H{sub 5}IO{sub 6} under similar reaction conditions gives rise to the anhydrous iodate, Yb(IO{sub 3}){sub 3}. Under supercritical conditions Lu{sup 3+} reacts with HIO{sub 3} and KIO{sub 4} to yield the isostructural Lu(IO{sub 3}){sub 3}. The structures have been determined by single-crystal X-ray diffraction. Crystallographic data are (MoK{alpha}, {lambda}=0.71073 A): Yb(IO{sub 3}){sub 3}, monoclinic, space group P2{sub 1}/n, a=8.6664(9)more » A, b=5.9904(6) A, c=14.8826(15) A, {beta}=96.931(2){sup o}, V=766.99(13), Z=4, R(F)=4.23% for 114 parameters with 1880 reflections with I>2{sigma}(I); Lu(IO{sub 3}){sub 3}, monoclinic, space group P2{sub 1}/n, a=8.6410(9), b=5.9961(6), c=14.8782(16) A, {beta}=97.028(2){sup o}, V=765.08(14), Z=4, R(F)=2.65% for 119 parameters with 1756 reflections with I>2{sigma}(I); Yb(IO{sub 3}){sub 3}(H{sub 2}O), monoclinic, space group C2/c, a=27.2476(15), b=5.6296(3), c=12.0157(7) A, {beta}=98.636(1){sup o}, V=1822.2(2), Z=8, R(F)=1.51% for 128 parameters with 2250 reflections with I>2{sigma}(I); Lu(IO{sub 3}){sub 3}(H{sub 2}O), monoclinic, space group C2/c, a=27.258(4), b=5.6251(7), c=12.0006(16) A, {beta}=98.704(2){sup o}, V=1818.8(4), Z=8, R(F)=1.98% for 128 parameters with 2242 reflections with I>2{sigma}(I). The f elements in all of the compounds are found in seven-coordinate environments and bridged with monodentate, bidentate, or tridentate iodate anions. Both Lu(IO{sub 3}){sub 3}(H and Yb(IO{sub 3}){sub 3}(H{sub 2}O) display distinctively different vibrational profiles from their respective anhydrous analogs. Hence, the Raman profile can be used as a complementary diagnostic tool to discern the different structural motifs of the compounds. - Graphical abstract: Four new metal iodates, Yb(IO{sub 3}){sub 3}, Lu(IO{sub 3}){sub 3}, Yb(IO{sub 3}){sub 3}(H{sub 2}O), and Lu(IO{sub 3}){sub 3}(H{sub 2}O), have all been isolated as single crystals through the use of hydrothermal reactions. Structural determinations using single-crystal X-ray diffraction have shown that the materials are all alike in that they contain two-dimensional structures. Vibrational profiles for all of the materials have been collected, using Raman spectroscopy, and analyzed.« less

Synthesis of modified proanthocyanidins: introduction of acyl substituents at C-8 of catechin. Selective synthesis of a C-4-->O-->C-3 ether-linked procyanidin-like dimer.

PubMed

Beauhaire, Josiane; Es-Safi, Nour-Eddine; Boyer, François-Didier; Kerhoas, Lucien; Guernevé, Christine le; Ducrot, Paul-Henri

2005-02-01

The regioselective introduction of substituents at C-8 of (+)-catechin is described, leading to the synthesis of several catechin derivatives with various substitution patterns to be used for the further synthesis of modified proanthocyanidins. Thereafter, a new 3-O-4 ether-linked procyanidin-like derivative was synthesized. Its formation was selectively achieved through TiCl(4)-catalyzed condensation of 4-(2-hydroxyethoxy)tetra-O-benzyl catechin with the 8-trifluoroacetyl adduct of tetra-O-benzyl catechin.

Photoionization of N,N,N[prime],N[prime]-tetramethylbenzidine in a mixed micelle of ionic and nonionic surfactants: Electron spin-echo modulation and electron spin resonance studies

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

Baglioni, P.; Rivara-Minten, E.; Stenland, C.

1991-11-28

Electron spin-echo modulation (ESEM) and electron spin resonance (ESR) spectra of the photogenerated N,N,N[prime],N[prime]-tetramethylbenzidine (TMB) cation radical in frozen mixed micelles of sodium dodecyl sulfate (SDS) or dodecyltrimethylammonium chloride (DTAC) and hexakis(ethylene glycol) monododecyl ether (C[sub 12]E[sub 6]), selectively deuterated along the poly(ethylene glycol) group (C[sub 12]D[sub 6]) or along the alkyl chain ((CD)[sub 12]E[sub 6]), have been studied as a function of the mixed-micelle composition in H[sub 2]O and D[sub 2]O. ESEM effects due to TMB[sup +] interactions with deuterium in D[sub 2]O show a decrease of the TMB[sup +]-water interactions for the system DTAC/C[sub 12]E[sub 6] and anmore » increase for the system SDS/C[sub 12]E[sub 6] that depend on the composition of the mixed micelle. The location of TMB[sup +] in the mixed micelles, deduced by comparing the modulation effects due to interactions of the photocation with water deuteriums or deuteriums of deuterated surfactants, is reported for the SDS/C[sub 12]E[sub 6] and DTAC/C[sub 12]E[sub 6] mixed micelles. The efficiency of charge separation upon the photoionization of TMB to produce TMB[sup +] measured by ESR correlates with the surface charge and with the degree of water penetration into the mixed micelle.« less

Non Covalent Interactions in Large Diamondoid Dimers in the Gas Phase - a Microwave Study

NASA Astrophysics Data System (ADS)

Perez, Cristobal; Sekutor, Marina; Fokin, Andrey A.; Blomeyer, Sebastian; Vishnevskiy, Yury V.; Mitzel, Norbert W.; Schreiner, Peter R.; Schnell, Melanie

2017-06-01

Accurate structure determination of large molecules still represents an ambitious challenge. Interesting benchmark systems for structure determination are large diamondoid dimers, whose structures are governed by strong intramolecular interactions. Recently, diamondoid dimers with unusually long central C-C bonds (up to 1.71 Å) were synthesized. This long central C-C bond was rationalized by numerous CH...HC-type dispersion attractions between the two halves of the molecule. The thermodynamic stabilization of molecules equipped with bulky groups has provided a conceptually new rationale, since until then it had been assumed that such molecules are highly unstable. We performed a broadband CP-FTMW spectroscopy study in the 2-8 GHz frequency range on oxygen-substituted diamondoid dimers (C_{26}H_{34}O_2, 28 heavy atoms) as well as diadamantyl ether to provide further insight into their structures. The experimental data are compared with results from quantum-chemical calculations and gas-phase electron diffraction. For the ether, we even obtained ^{13}C and ^{18}O isotopologues to generate the full heavy-atom substitution structure.

Kinetic Studies of the Thermal Decomposition of Methylperoxynitrate and of Ozone-Olefin Reactions.

NASA Astrophysics Data System (ADS)

Bahta, Abraha

This research concerns the thermal decomposition kinetics of CH(,3)O(,2)NO(,2) and laboratory kinetic measurements of ozone-olefin reactions. In the first system, the thermal decomposition rate of CH(,3)O(,2)NO(,2) was studied in the temperature range of 256-268 K at (TURN)350 torr total pressure and in the pressure range of 50-720 torr at 263 K by the perturbation of the equilibrium: (UNFORMATTED TABLE FOLLOWS). CH(,3)O(,2) + NO(,2) (+M) (DBLARR) CH(,3)O(,2)NO(,2) (+M) (3,-3). with NO. CH(,3)O(,2) + NO (--->) CH(,3)O + NO(,2) (4). (TABLE ENDS). The CH(,3)O(,2)NO(,2) was generated in situ by the photolysis of Cl(,2) in the presence of O(,2), CH(,4) and NO(,2). The decomposition kinetics were monitored in the presence of NO by the change in ultraviolet absorption at 250 nm. The Arrhenius expression obtained for the thermal decomposition is k(,-3) = 6 x 10('15) exp{-(21,000 (+OR-) 1500)/RT} sec('-1) at (TURNEQ)350 torr total pressure (mostly CH(,4)) where R = 1.987 cal/mole('-) K. The uncertainty in the Arrhenius parameters can be greatly reduced by combining this expression with data for k(,3) and thermodynamics data to give k(,-3) = (6 (+OR-) 3) x 10('15) exp{-(21,300 (+OR-) 300)/RT} sec('-1) at (TURNEQ)350 torr total pressure. Computations based on the pressure dependence of the forward reaction give k(,-3)('(INFIN)) = 2.1 x 10('16) exp{-(21,700 (+OR -) 300)/RT} sec('-1) k(,-3)('(DEGREES)) = 3.3 x 10(' -4) exp{-(20,150 x 300)/RT} cm('3) sec('-1). At 263 K the equilibrium constant K(,3,-3){263 K} is determined to be (2.68 (+OR-) 0.26) x 10('-10) cm('3). In the stratosphere the CH(,3)O(,2)NO(,2) lifetime will be controlled by play a role in the NO(,x) budget of the lower stratosphere. In the second part, the kinetics of the reactions of O(,3) with C(,2)H(,4), C(,3)H(,4), 1,3-C(,4)H(,6), and trans-1,3-C(,5)H(,8) were studied with initial olefin-to -ozone ratios (GREATERTHEQ) 4.9, in the presence of excess O(,2), and over the temperature range 232 to 300 K. The initial O(,3) pressure was varied from 5-18 mtorr, and the olefin pressure was varied from 0.1 to 4.5 torr (C(,2)H(,4)), 2.8 to 39.6 torr (allene), 52.7 to 600 mtorr (1,3-C(,4)H(,6)), or 26.2 to 106 mtorr (1,3-C(,5)H(,8)). The O(,3) decay was monitored by ultraviolet absorption. The reaction is first order in both O(,3) and olefin. The rate coefficients are independent of the O(,2) pressure (100-400 torr), and in the case of the O(,3)/C(,2)H(,4) system, the rate coefficients are independent of the nature of the diluent gas--N(,2), O(,2), and air were used. These measured rate coefficients were found to fit the Arrhenius expressions: (UNFORMATTED TABLE FOLLOWS). For C(,2)H(,4): k{232-298 K}=(7.88(+OR -)0.46)x10('-15) exp{-(5085(+OR-)580)/RT}. For C(,3)H(,4): k{252-298 K}=(1.92(+OR -)0.14)x10('-15) exp{-(5430(+OR-)830)/RT}. For 1,3-C(,4)H(,6): k{254-299 K}=(2.43(+OR -)0.15)x10('-14) exp{-(4900(+OR-)670)}. and. For t-1,3-C(,5)H(,8): k{262-298 K}=(6.56(+OR -)0.40)x10('-12). exp{-(7140(+OR-)860)/RT}. (TABLE ENDS). cm('3) s('-1), where the uncertainties represent one standard deviation.

Crystallization process of zeolite rho prepared by hydrothermal synthesis using 18-crown-6 ether as organic template.

PubMed

Araki, Sadao; Kiyohara, Yasato; Tanaka, Shunsuke; Miyake, Yoshikazu

2012-06-15

There are many viewpoints on the formation mechanisms for zeolites, but the details are not clear. An understanding of the elementary steps for their formation is important for the development of large-scale membranes and efficient manufacturing processes. In this study, the effects of silicon, aluminum, and the incorporation of 18-crown-6 (18C6) ether, on the formation of zeolite rho, using 18C6 as the structure directing agent (SDA) have been investigated by using field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray fluorescence spectrometry (EDX), nuclear magnetic resonance spectroscopy (NMR), thermo gravimetric analysis (TGA), and the pH measurement. These results suggested that a zeolite rho has four synthesis steps; (1) 0-3 h, the dehydration and condensation reaction between the silica and alumina to form amorphous aluminosilicates; (2) 3-20 h, the particle growth and aggregation process for the amorphous aluminosilicates; (3) 20-48 h, the crystallization and crystal growth of zeolite rho, with the incorporation of 18C6; and (4) 48-96 h, gentle growth with an increase in Na/Si ratio and a change in rate for the bounding state between the silica- and the alumina-based species. We consider the above to reflect the four steps for the formation of zeolite rho. Copyright © 2012 Elsevier Inc. All rights reserved.

Crystal structure of catena-poly[[[tetra-aqua-zinc(II)]-μ-1,4-bis-[4-(1H-imidazol-1-yl)benzo-yl]piperazine] dinitrate monohydrate].

PubMed

Hou, Chen; Gan, Hong-Mei; Liu, Jia-Cheng

2015-05-01

In the title polymeric complex, {[Zn(C24H22N6O2)(H2O)4](NO3)2·2H2O} n , the Zn(II) cation, located about a twofold rotation axis, is coordinated by two imidazole groups and four water mol-ecules in a distorted N2O4 octa-hedral geometry; among the four coordinate water mol-ecules, two are located on the same twofold rotation axis. The 1,4-bis-[4-(1H-imidazol-1-yl)benzo-yl]piperazine] ligand is centro-symmetric, with the centroid of the piperazine ring located on an inversion center, and bridges the Zn(II) cations, forming polymeric chains propagating along [201]. In the crystal, O-H⋯O and weak C-H⋯O hydrogen bonds link the polymeric chains, nitrate anions and solvent water mol-ecules into a three-dimensional supra-molecular architecture. A short O⋯O contact of 2.823 (13) Å is observed between neighboring nitrate anions.

4-(4-Bromo-phen-yl)-1-(2,6-difluoro-benz-yl)-3-(3,4,5-trimeth-oxy-phen-yl)-1H-1,2,4-triazole-5(4H)-thione.

PubMed

Fun, Hoong-Kun; Ooi, Chin Wei; Chandrakantha, B; Isloor, Arun M; Shetty, Prakash

2012-01-01

In the title compound, C(24)H(20)BrF(2)N(3)O(3)S, the triazole ring (r.m.s. deviation = 0.0107 Å) makes dihedral angles of 28.18 (14), 63.76 (14) and 77.01 (18)°, respectively, with the trimeth-oxy-, bromo-, and difluoro-substituted benzene rings. The C atoms of the meta meth-oxy groups are roughly coplanar with their ring [displacements = -0.289 (4) and 0.083 (7) Å], whereas the C atom of the para group is displaced [1.117 (3) Å]. In the crystal, inversion dimers linked by two pairs of C-H⋯O hydrogen bonds occur. The ring motif of the two hydrogen bonds to their symmetry-generated O-atom acceptors is R(2) (2)(8).

Water-soluble titanium alkoxide material

DOEpatents

Boyle, Timothy J.

2010-06-22

A water soluble, water stable, titanium alkoxide composition represented by the chemical formula (OC.sub.6H.sub.6N).sub.2Ti(OC.sub.6H.sub.2(CH.sub.2N(CH.sub.3).sub.2).sub- .3-2,4,6).sub.2 with a theoretical molecular weight of 792.8 and an elemental composition of 63.6% C, 8.1% H, 14.1% N, 8.1% O and 6.0% Ti.

Electrically Conducting Polymer Nanoparticles to Selectively Target and Treat Metastatic Colorectal Cancer

DTIC Science & Technology

2014-09-01

2,5-di(2-ethylhexyl)-pyrrolo[3,4-c] pyrrole -1,4-dione acceptor 2 toluene reflux, 48 hrs Pd(PPh3)4 Br A Br SSMe3Sn SnMe3 M1 SS P3 S N NO O S n C8H18...bis(2-ethylhexyl)-2,6-bis(trimethyl-stannyl)-4H-cyclopenta-[2,1-b;3,4- b’]dithiophene with 3,6-dithien-2-yl-2,5-di(2-ethylhexyl)-pyrrolo[3,4-c] pyrrole ...cyclopenta-[2,1-b;3,4-b’]- dithiophene (M1). Synthesis of 2,5-Diethylhexyl-3,6-bis(5-bromothiophen-2-yl)pyrrolo[3,4-c]- pyrrole -1,4-dione (A). The

Piperidinium bis­(2-oxidobenzoato-κ2 O 1,O 2)borate

PubMed Central

Tang, Zhi-Hua; Huang, Chaojun

2009-01-01

The asymmetric unit of the title compound, C5H12N+·C14H8BO6 − or [C5H12N][BO4(C7H4O)2], contains two piperidinium cations and two bis­(salicylato)borate anions. The coordination geometries around the B atoms are distorted tetra­hedral. In the two mol­ecules, the aromatic rings are oriented at dihedral angles of 76.27 (3) and 83.86 (3)°. The rings containing B atoms have twist-boat conformations, while the two cations adopt chair conformations. In the crystal, the component species are linked by N—H⋯O hydrogen bonds. In the crystal structure, intra- and inter­molecular N—H⋯O hydrogen bonds link the mol­ecules. PMID:21581628

Reduced 3,4'-bipyrazoles from a simple pyrazole precursor: synthetic sequence, molecular structures and supramolecular assembly.

PubMed

Cuartas, Viviana; Insuasty, Braulio; Cobo, Justo; Glidewell, Christopher

2017-10-01

The reaction of 5-chloro-3-methyl-1-phenyl-1H-pyrazole-4-carbaldehyde and N-benzylmethylamine under microwave irradiation gives 5-[benzyl(methyl)amino]-3-methyl-1-phenyl-1H-pyrazole-4-carbaldehyde, C 19 H 19 N 3 O, (I). Subsequent reactions under basic conditions, between (I) and a range of acetophenones, yield the corresponding chalcones. These undergo cyclocondensation reactions with hydrazine to produce reduced bipyrazoles which can be N-formylated with formic acid or N-acetylated with acetic anhydride. The structures of (I) and of representative examples from this reaction sequence are reported, namely the chalcone (E)-3-{5-[benzyl(methyl)amino]-3-methyl-1-phenyl-1H-pyrazol-4-yl}-1-(4-bromophenyl)prop-2-en-1-one, C 27 H 24 BrN 3 O, (II), the N-formyl derivative (3RS)-5'-[benzyl(methyl)amino]-3'-methyl-1',5-diphenyl-3,4-dihydro-1'H,2H-[3,4'-bipyrazole]-2-carbaldehyde, C 28 H 27 N 5 O, (III), and the N-acetyl derivative (3RS)-2-acetyl-5'-[benzyl(methyl)amino]-5-(4-methoxyphenyl)-3'-methyl-1'-phenyl-3,4-dihydro-1'H,2H-[3,4'-bipyrazole], which crystallizes as the ethanol 0.945-solvate, C 30 H 31 N 5 O 2 ·0.945C 2 H 6 O, (IV). There is significant delocalization of charge from the benzyl(methyl)amino substituent onto the carbonyl group in (I), but not in (II). In each of (III) and (IV), the reduced pyrazole ring is modestly puckered into an envelope conformation. The molecules of (I) are linked by a combination of C-H...N and C-H...π(arene) hydrogen bonds to form a simple chain of rings; those of (III) are linked by a combination of C-H...O and C-H...N hydrogen bonds to form sheets of R 2 2 (8) and R 6 6 (42) rings, and those of (IV) are linked by a combination of O-H...N and C-H...O hydrogen bonds to form a ribbon of edge-fused R 2 4 (16) and R 4 4 (24) rings.

Assembly of a new inorganic-organic frameworks based on [Sb4Mo12(OH)6O48]10- polyanion

NASA Astrophysics Data System (ADS)

Thabet, Safa; Ayed, Meriem; Ayed, Brahim; Haddad, Amor

2014-10-01

A new organic-inorganic hybrid material, (C4N2H7)8[K(H2O)]2[Sb4Mo12(OH)6O48]ṡ16H2O (1) has been isolated by the conventional solution method and characterized by elemental analysis, single-crystal X-ray diffraction, infrared spectroscopy, UV-visible spectroscopies, cyclic voltammetry and TG-DTA analysis. The compound crystallizes in the triclinic space group P - 1 with a = 13.407(6) Å, b = 13.906(2) Å, c = 14.657(7) Å, α = 77.216(9)°, β = 71.284(6)°, γ = 71.312(3)° and Z = 1. The crystal structure exhibits an infinite 1D inorganic structure built from [Sb4Mo12(OH)6O48]10- clusters and potassium cations; adjacent chains are further joined up hydrogen bonding interactions between protonated 2-methylimidazolim cations, water molecules and polyoxoanions to form a 3D supramolecular architecture.

Supply of avocado starch (Persea americana mill) as bioplastic material

NASA Astrophysics Data System (ADS)

Ginting, M. H. S.; Hasibuan, R.; Lubis, M.; Alanjani, F.; Winoto, F. A.; Siregar, R. C.

2018-02-01

The purpose of this study was to determine the effect of time precipitation of avocado slurry seed to yield of starch. Starch analysis included starch content, moisture content, amylose content, amylopectin content, ash content, protein content, fat content, Fourier transform infra red analysis and rapid visco analyzer. Supply of starch from avocado seeds was used by extraction method. Every one hundred grams of avocado slurry was precipitated by gravity with variations for 4 hours, 8 hours, 12 hours, 16 hours, 20 hours and 24 hours. The Starch yield was washed, and dried using oven at 70°C for 30 minutes. Starch yield was the highest as 24.20 gram at 24 hours. The result of starch characterization was 73.62%, water content 16.6%, amylose 0.07%, amylopectin 73.55%, ash content 0.23%, protein content 2.16%, fat content 1.09%. Rapid visco analyzer obtained at 91.33°C of gelatinization temperature. Scanning electron microscopy analyzes obtained 20 μm oval-shaped starch granules. Fourier Transform Infra Red analysis of starch obtained the peak spectrum of O-H group of alcohols, C-H alkanes and C-O ether.

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.

μ-Hexa­thio­metadiphosphato-bis­[(1,4,7,10,13,16-hexa­oxa­cyclo­octa­decane-κ6 O)rubidium] aceto­nitrile disolvate

PubMed Central

Gjikaj, Mimoza; Pook, Niels-Patrick; Qarri, Flora

2013-01-01

The asymmetric unit of the title compound, [Rb2(P2S6)(C12H24O6)2]·2CH3CN, contains one half of an [Rb(18-crown-6)2]2[P2S6] unit and one aceto­nitrile solvent mol­ecule. The [Rb(18-crown-6)]2[P2S6] unit is completed by inversion symmetry. Its Rb+ ion is situated near the centre of the macrocyclic cavity, but is displaced by 0.8972 (1) Å from the O atoms of the crown in the direction of the [P2S6]2− moiety. The overall coordination number of the cation is eight, defined by the six crown ether O atoms and by two terminal S atoms of the [P2S6]2− anion. The hexa­thio­metadiphosphate anion is built up from two tetra­hedral PS4 units joined together by a common edge. The crystal structure is characterized by alternating layers of [Rb(18-crown-6)]2[P2S6] and aceto­nitrile solvent mol­ecules stacked along [010]. PMID:24860286

Differential response of pitted morning glory and ivy leaf morning glory to acifluorfen, fomesafen, and lactofen

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

Higgins, J.M.

1987-01-01

Field and laboratory investigations were conducted to examine the response of soybeans (Glycine max (L.) Merr.), pitted morning glory (Ipomoea lacunosa L.number/sup 1/ IPOLA), and ivy leaf morning glory (Ipomoea hederacea (L.) Jacq. number IPOHE) to acifluorfen, fomesafen, and lactofen. In field studies, greatest soybean injury was observed with acifluorfen and lactofen. All treatments provided 80% or greater control of pitted morning glory 15 days after treatment. Only acifluorfen and fomesafen at 0.6 kg ai ha/sup -1/ provided 80% or greater ivy leaf morning glory. The differential response of pitted morning glory and ivy leaf morning glory to these diphenylmore » ether herbicides was reflected in soybean seed yields. In laboratory studies, 71 to 84% of applied /sup 14/C-acifluorfen was not absorbed into the leaf surface of ivy leaf morning glory. Thirty-two to 46% of applied acifluorfen was recovered from the leaf surface of pitted morning glory. Sixty-four percent of applied /sup 14/C-lactofen was recovered from leaf surfaces of both morning glory species 96 h after treatment. Treated leaves of pitted morning glory contained 35 to 37% more /sup 14/C-acifluorfen than ivy leaf morning glory. Less than 28% of applied /sup 14/C-lactofen was absorbed into treated leaves of both morning glory species at 24, 48, and 96 h harvests.« less

The syntheses and characterizations of vanadium complexes with 1,2-dihydroxyanthraquinone and the structure-effect relationship in their in vitro anticancer activities.

PubMed

Du, Shizhen; Feng, Jun; Lu, Xiaoming; Wang, Guo

2013-07-14

[V(V)O2(O2C14H6O2)(C5N2H12)](C5N2H13)(CH3OH) (1) and {Na[V(V)O(O2C14H6O2)2][(CH3)2NCHO]}n (2) have been synthesized by the reaction of V2O5 and NaVO3 with aromatic 1,2-diol (1,2-dihydroxyanthraquinone), and their molecular and crystal structures have been determined by X-ray diffraction. MTT assay tests of the V(V)O2L(A)L(B) and V(V)OL2 complexes against cancer cells have revealed that, when L is catechol, VOL2 showed broad-spectrum, high anticancer activities which were proportional to their concentration; however when L is naphthol or alizarin, VOL2 displayed little effect towards the cancer cells; moreover, complex 1 in the coordination model of V(V)O2L(A)L(B) showed specifically higher inhibition (88.65%) against HCT-8 than the clinical anticancer drug Fu-5 (69.97%). The results revealed that both the V(V) and the ligands cannot influence the inhibition against cancer cells individually. The mechanism of the broad-spectrum anticancer activities of VOL2 when L is catechol ligand might originate from the redox activities of V(V)/V(IV) which regulate the concentration of ROS (reactive oxygen species). N-Methylpiperazine formed as a by-product in complex 1 was confirmed by (1)H NMR and its formation mechanism catalyzed by V2O5 has been deduced.

Oxygenates vs. synthesis gas

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

Kamil Klier; Richard G. Herman; Alessandra Beretta

1999-04-01

Methanol synthesis from H{sub 2}/CO has been carried out at 7.6 MPa over zirconia-supported copper catalysts. Catalysts with nominal compositions of 10/90 mol% and 30/70 mol% Cu/ZrO{sub 2} were used in this study. Additionally, a 3 mol% cesium-doped 10/90 catalyst was prepared to study the effect of doping with heavy alkali, and this promoter greatly increased the methanol productivity. The effects of CO{sub 2} addition, water injection, reaction temperature, and H{sub 2}/C0 ratio have been investigated. Both CO{sub 2} addition to the synthesis gas and cesium doping of the catalyst promoted methanol synthesis, while inhibiting the synthesis of dimethyl ether.more » Injection of water, however, was found to slightly suppress methanol and dimethyl ether formation while being converted to CO{sub 2} via the water gas shift reaction over these catalysts. There was no clear correlation between copper surface area and catalyst activity. Surface analysis of the tested samples revealed that copper tended to migrate and enrich the catalyst surface. The concept of employing a double-bed reactor with a pronounced temperature gradient to enhance higher alcohol synthesis was explored, and it was found that utilization of a Cs-promoted Cu/ZnO/Cr{sub 2}O{sub 3} catalyst as a first lower temperature bed and a Cs-promoted ZnO/Cr{sub 2}O{sub 3} catalyst as a second high-temperature bed significantly promoted the productivity of 2-methyl-1-propanol (isobutanol) from H{sub 2}/CO synthesis gas mixtures. While the conversion of CO to C{sub 2+} oxygenates over the double-bed configuration was comparable to that observed over the single Cu-based catalyst, major changes in the product distribution occurred by the coupling to the zinc chromite catalyst; that is, the productivity of the C{sub 1}-C{sub 3} alcohols decreased dramatically, and 2-methyl branched alcohols were selectively formed. The desirable methanol/2-methyl oxygenate molar ratios close to 1 were obtained in the present double-bed system that provides the feedstock for the synthesis of high octane and high cetane ethers, where the isobutanol productivity was as high as 139 g/kg cat/hr. Higher alcohol synthesis has been investigated over a Cs/Cu/ZnO/Cr{sub 2}O{sub 3} catalyst at temperatures higher (up to 703K) than those previously utilized, and no sintering of the catalyst was observed during the short-term testing. However, the higher reaction temperatures led to lower CO conversion levels and lower yield of alcohols, especially of methanol, because of equilibrium limitations. With the double catalyst bed configuration, the effect of pressure in the range of 7.6--12.4 MPa on catalyst activity and selectivity was studied. The upper bed was composed of the copper-based catalyst at 598K, and the lower bed consisted of a copper-free Cs-ZnO/Cr{sub 2}O{sub 3} catalyst at a high temperature of 678K. High pressure was found to increase CO conversion to oxygenated products, although the increase in isobutanol productivity did not keep pace with that of methanol. It was also shown that the Cs/Cu/ZnO/Cr{sub 2}O{sub 3} catalyst could be utilized to advantage as the second-bed catalyst at 613--643K instead of the previously used copper-free Cs-ZnO/ Cr{sub 2}O{sub 3} catalyst at higher temperature, With double Cs/Cu/ZnO/Cr{sub 2}O{sub 3} catalysts, high space time yields of up to 202 g/kg cat/hr, with high selectivity to isobutanol, were achieved.« less

Evaluation of mosquito larvicidal activity of fruit extracts of Acacia auriculiformis against the Japanese encephalitis vector Culex vishnui.

PubMed

Barik, Mousumi; Rawani, Anjali; Laskar, Subrata; Chandra, Goutam

2018-02-19

The larvicidal potentiality of crude and ethyl acetate extracts of fruits of Acacia auriculiformis was investigated against all the larval instars of JE vector Culex vishnui. The crude extracts showed good results against all the larval instars with highest mortality at 0.09%. Highest mortality was found at 300 ppm of ethyl acetate extract. Lowest LC 50 value was obtained at 72 h for third instar larvae. Non target organisms tested, showed no to very less mortality to ethyl acetate solvent extract. Presence of N-H stretching, a C=O stretching, C=C and C-N stretching vibrations of secondary amide or amine group were confirmed from IR analysis. GC-MS analysis revealed the presence of three compounds namely Ethane 2-chloro-1,1-dimethoxy, Acetic acid, 1-methyl ether ester and [4-[1-[3,5-Dimethyl-4[(trimethylsilyl)oxy)phenyl]-1,3-dimethylbutyl)-2,6dimethylphenoxy)(trimethyl) silane, responsible for mosquito larval death.

Effect of diphenyl ether herbicides and oxadiazon on porphyrin biosynthesis in mouse liver, rat primary hepatocyte culture and HepG2 cells.

PubMed

Krijt, J; van Holsteijn, I; Hassing, I; Vokurka, M; Blaauboer, B J

1993-01-01

The effects of the herbicides fomesafen, oxyfluorfen, oxadiazon and fluazifop-butyl on porphyrin accumulation in mouse liver, rat primary hepatocyte culture and HepG2 cells were investigated. Ten days of herbicide feeding (0.25% in the diet) increased the liver porphyrins in male C57B1/6J mice from 1.4 +/- 0.6 to 4.8 +/- 2.1 (fomesafen) 16.9 +2- 2.9 (oxyfluorfen) and 25.9 +/- 3.1 (oxadiazon) nmol/g wet weight, respectively. Fluazifop-butyl had no effect on liver porphyrin metabolism. Fomesafen, oxyfluorfen and oxadiazon increased the cellular porphyrin content of rat hepatocytes after 24 h of incubation (control, 3.2 pmol/mg protein, fomesafen, oxyfluorfen and oxadiazon at 0.125 mM concentration 51.5, 54.3 and 44.0 pmol/mg protein, respectively). The porphyrin content of HepG2 cells increased from 1.6 to 18.2, 10.6 and 9.2 pmol/mg protein after 24 h incubation with the three herbicides. Fluazifop-butyl increased hepatic cytochrome P450 levels and ethoxy- and pentoxyresorufin O-dealkylase (EROD and PROD) activity, oxyfluorfen increased PROD activity. Peroxisomal palmitoyl CoA oxidation increased after fomesafen and fluazifop treatment to about 500% of control values both in mouse liver and rat hepatocytes. Both rat hepatocytes and HepG2 cells can be used as a test system for the porphyrogenic potential of photobleaching herbicides.

Synthesis, crystal structure, and vibrational study of K2Cu(HPO4)2·6H2O: A new metal hydrogenphosphate compound

NASA Astrophysics Data System (ADS)

Ettoumi, Houda; Bulou, Alain; Suñol, Joan Josep; Mhiri, Tahar

2015-11-01

The study reports on the synthesis, single-crystal X-ray structure, and infrared and polarized Raman spectra of a new metal phosphate. The chemical formula of the compound K2Cu(HPO4)2·6H2O resembled that of Tutton salts. The compound crystallized in the monoclinic system, space group P21/c, with a = 6.166(9), b = 12.118(19), c = 9.077(14) Å, β = 104.33(2), and Z = 2. The compound consisted of transition metal cations octahedrally coordinated by six water molecules, [Cu(H2O)6]2+, HPO4 pseudo-tetrahedra, and KO8 polyhedra. The KO8 polyhedra shared two edges with two HPO4 groups, two corners with the two other HPO4 groups, and two corners with Cu(H2O)6. The connection between [Cu(H2O)6]2+ octahedral and (HPO4)2- pseudo-tetrahedra was reinforced by hydrogen bonds formed between the water molecules and other oxygen atoms linked to the P atom. These structural results were corroborated by infrared and polarized Raman spectroscopy.

"Leaching or not leaching": an alternative approach to antimicrobial materials via copolymers containing crown ethers as active groups.

PubMed

De Rosa, M; Vigliotta, G; Soriente, A; Capaccio, V; Gorrasi, G; Adami, R; Reverchon, E; Mella, M; Izzo, L

2017-03-28

In this work, new copolymers containing either MMA and 18C6 crown-ether pendants, or PEG, MMA and 18C6 crown-ether pendants were synthesized to test the idea that sequestering structural alkali-earth ions from the bacterial outer membrane (OM) may lead to bacterial death. The copolymers were obtained either via uncontrolled radical polymerization or ATRP; the latter approached allowed us to produce not only linear copolymers but also branched Y-like structures. After checking for the capability of complexing magnesium and calcium ions, the antimicrobial activity of all copolymers was tested placing their casted plaques in contact with pure water E. coli suspensions. All plaques adsorbed alkali-earth ions and killed bacteria, albeit with different antimicrobial efficiencies. Differences in the latter characteristic were attributed to different plaque roughness. The role of the 18C6 crown-ether pendants was elucidated by pre-saturating plaques with Mg/Ca ions, the marked reduction in antimicrobial efficiency indicating that losing the latter from OM due to surface complexation does play an important role in killing bacteria at short (<5 h) contact times. At longer times, the mode of action is instead related to the poly-cationic nature acquired by the plaques due to ion sequestering.

Thermal conductivity of Ca3Co2O6 single crystals

NASA Astrophysics Data System (ADS)

Che, H. L.; Shi, J.; Wu, J. C.; Rao, X.; Liu, X. G.; Zhao, X.; Sun, X. F.

2018-05-01

Ca3Co2O6 is a rare example of one-dimensional Ising spin-chain material with the moments preferentially aligned along the c axis. In this work, we study the c-axis thermal conductivity (κc) of Ca3Co2O6 single crystal at low temperatures down to 0.3 K and in magnetic fields up to 14 T. The zero-field κc(T) shows a large phonon peak and can be well fitted by using the classical Debye model, which indicates that the heat transport is purely phononic. Moreover, the low-T κc(H) isotherms with H || c display a field-independent behavior. These results indicate that there is no contribution of magnetic excitations to the thermal conductivity in Ca3Co2O6, neither carrying heat nor scattering phonons, which can be attributed to the Ising-like spin anisotropy.

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.

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

Rivenet, Murielle; Vigier, Nicolas; Roussel, Pascal

Six new layered uranyl vanadates (NH{sub 4}){sub 2}[(UO{sub 2}){sub 2}V{sub 2}O{sub 8}] (1), (H{sub 2}EN)[(UO{sub 2}){sub 2}V{sub 2}O{sub 8}] (2), (H{sub 2}DAP)[(UO{sub 2}){sub 2}V{sub 2}O{sub 8}] (3), (H{sub 2}PIP)[(UO{sub 2}){sub 2}(VO{sub 4}){sub 2}].0,8H{sub 2}O (4), (H{sub 2}DMPIP)[(UO{sub 2}){sub 2}V{sub 2}O{sub 8}] (5), (H{sub 2}DABCO)[(UO{sub 2}){sub 2}(VO{sub 4}){sub 2}] (6) were prepared from mild-hydrothermal reactions using 1,2-ethylenediamine (EN); 1,3-diaminopropane (DAP); piperazine (PIP); 1-methylpiperazine (MPIP); 1,4-diazabicyclo[2,2,2]octane (DABCO). The structures of 1, 4, 5 and 6 were solved using single-crystal X-ray diffraction data while the structural models of 2 and 3 were established from powder X-ray diffraction data. In compounds 1, 2, 3more » and 5, the uranyl-vanadate layers are built from dimers of edge-shared UO{sub 7} pentagonal bipyramids and dimers of edge-shared VO{sub 5} square pyramids further connected through edge-sharing. In 1 and 3, the layers are identical to that occurring in the carnotite group of uranyl-vanadates. In 2 and 5, the V{sub 2}O{sub 8} dimers differ in orientation leading to a new type of layer. The layers of compound 4 and 6 are built from chains of edge-shared UO{sub 7} pentagonal bipyramids connected by VO{sub 4} tetrahedra and are of uranophane-type anion topology. For the six compounds, the ammonium or organoammonium cation resides in the space between the inorganic layers. Crystallographic data: 1 monoclinic, space group P2{sub 1}/c with a=6.894(2), b=8.384(3), c=10.473(4) A and {beta}=106.066(5){sup o}, 2 monoclinic, space group P2{sub 1}/a with a=13.9816(6), b=8.6165(3), c=10.4237(3) A and {gamma}=93.125(3){sup o}, 3 orthorhombic, space group Pmcn with a=14.7363(8), b=8.6379(4) and c=10.4385(4) A, 4 monoclinic, space group C2/m with a=15.619(2), b=7.1802(8), c=6.9157(8) A and {beta}=101.500(2){sup o}, 5 monoclinic, space group P2{sub 1}/b with a=9.315(2), b=8.617(2), c=10.5246(2) A and {gamma}=114.776(2){sup o}, 6 monoclinic, space group C2/m with a=17.440(2), b=7.1904(9), c=6.8990(8) A and {beta}=98.196(2){sup o}. - Graphical abstract: The three types of layer in layered uranyl-vanadates using diamine as a structure-directing agent.« less

Oxidative cleavage of non-phenolic β-O-4 lignin model dimers by an extracellular aromatic peroxygenase

Treesearch

Matthias Kinne; Marzena Poraj-Kobielska; Rene Ullrich; Paula Nousiainen; Jussi Sipilä; Katrin Scheibner; Kenneth E. Hammel; Martin Hofrichter

2011-01-01

The extracellular aromatic peroxygenase of the agaric fungus Agrocybe aegerita catalyzed the H2O2-dependent cleavage of non-phenolic arylgiycerol-ß-aryl ethers (ß-O-4 ethers). For instance 1-(3,4-dimethoxyphenyl)-2-(2-methoxy-phenoxy)propane-1,3-diol, a recalcitrant dimeric lignin model compound that represents the major...

Toxicology Study of Diisopropyl Methylphosphonate and Dicyclopentadiene in Mallard Ducks, Bobwhite Quail and Mink.

DTIC Science & Technology

1979-06-01

hematology, etc.) measured during the chronic tests. In the OCPD tissue residue study, Mallards and Bobwhites were fed or dosed with 14C-DCPD at the...Table 73. Body weight gain of 17-day-old Mallard ducklings during 3-day post-treatment on non-treated feed after withdrawal of OCPD -treated feed...treatment recovery period ................... 261 Table 107. Feed consumption, body weight, and amount of chemical ingested by adult mink fed OCPD at

Functionalization of metallabenzenes through nucleophilic aromatic substitution of hydrogen.

PubMed

Clark, George R; Ferguson, Lauren A; McIntosh, Amy E; Söhnel, Tilo; Wright, L James

2010-09-29

The cationic metallabenzenes [Ir(C(5)H(4){SMe-1})(κ(2)-S(2)CNEt(2))(PPh(3))(2)]PF(6) (1) and [Os(C(5)H(4){SMe-1})(CO)(2)(PPh(3))(2)][CF(3)SO(3)] (2) undergo regioselective nucleophilic aromatic substitution of hydrogen at the metallabenzene ring position γ to the metal in a two-step process that first involves treatment with appropriate nucleophiles and then oxidation. Thus, reaction between compound 1 and NaBH(4), MeLi, or NaOEt gives the corresponding neutral iridacyclohexa-1,4-diene complexes Ir(C(5)H(3){SMe-1}{H-3}{Nu-3})(κ(2)-S(2)CNEt(2))(PPh(3))(2) (Nu = H (3), Me (4), OEt (5)). Similarly, reaction between 2 and NaBH(4) or MeLi gives the corresponding osmacyclohexa-1,4-diene complexes Os(C(5)H(3){SMe-1}{H-3}{Nu-3})(CO)(2)(PPh(3))(2) (Nu = H (8), Me (9)). The metallacyclohexa-1,4-diene rings in all these compounds are rearomatized on treatment with the oxidizing agent O(2), CuCl(2), or 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ). Accordingly, the cationic metallabenzene 1 or 2 is returned after reaction between 3 and DDQ/NEt(4)PF(6) or between 8 and DDQ/NaO(3)SCF(3), respectively. The substituted cationic iridabenzene [Ir(C(5)H(3){SMe-1}{Me-3})(κ(2)-S(2)CNEt(2))(PPh(3))(2)]PF(6) (6) or [Ir(C(5)H(4){SMe-1}{OEt-3})(κ(2)-S(2)CNEt(2))(PPh(3))(2)]PF(6) (7) is produced in a similar manner through reaction between 4 or 5, respectively, and DDQ/NEt(4)PF(6), and the substituted cationic osmabenzene [Os(C(5)H(3){SMe-1}{Me-3})(CO)(2)(PPh(3))(2)]Cl (10) is formed in good yield on treatment of 9 with CuCl(2). The starting cationic iridabenzene 1 is conveniently prepared by treatment of the neutral iridabenzene Ir(C(5)H(4){SMe-1})Cl(2)(PPh(3))(2) with NaS(2)CNEt(2) and NEt(4)PF(6), and the related starting cationic osmabenzene 2 is obtained by treatment of Os(C(5)H(4){S-1})(CO)(PPh(3))(2) with CF(3)SO(3)CH(3) and CO. The stepwise transformations of 1 into 6 or 7 as well as 2 into 10 provide the first examples in metallabenzene chemistry of regioselective nucleophilic aromatic substitutions of hydrogen by external nucleophiles. DFT calculations have been used to rationalize the preferred sites for nucleophilic attack at the metallabenzene rings of 1 and 2. The crystal structures of 1, 3, 6, and 7 have been obtained.

Partial oxidation of dimethyl ether using the structured catalyst Rh/Al2O3/Al prepared through the anodic oxidation of aluminum.

PubMed

Yu, B Y; Lee, K H; Kim, K; Byun, D J; Ha, H P; Byun, J Y

2011-07-01

The partial oxidation of dimethyl ether (DME) was investigated using the structured catalyst Rh/Al2O3/Al. The porous Al2O3 layer was synthesized on the aluminum plate through anodic oxidation in an oxalic-acid solution. It was observed that about 20 nm nanopores were well developed in the Al2O3 layer. The thickness of Al2O3 layer can be adjusted by controlling the anodizing time and current density. After pore-widening and hot-water treatment, the Al2O3/Al plate was calcined at 500 degrees C for 3 h. The obtained delta-Al2O3 had a specific surface area of 160 m2/g, making it fit to be used as a catalyst support. A microchannel reactor was designed and fabricated to evaluate the catalytic activity of Rh/Al2O3/Al in the partial oxidation of DME. The structured catalyst showed an 86% maximum hydrogen yield at 450 degrees C. On the other hand, the maximum syngas yield by a pack-bed-type catalyst could be attained by using a more than fivefold Rh amount compared to that used in the structured Rh/Al2O3/Al catalyst.

Thermodynamic equilibrium calculations of hydrogen production from the combined processes of dimethyl ether steam reforming and partial oxidation

NASA Astrophysics Data System (ADS)

Semelsberger, Troy A.; Borup, Rodney L.

Thermodynamic analyses of producing a hydrogen-rich fuel-cell feed from the combined processes of dimethyl ether (DME) partial oxidation and steam reforming were investigated as a function of oxygen-to-carbon ratio (0.00-2.80), steam-to-carbon ratio (0.00-4.00), temperature (100 °C-600 °C), pressure (1-5 atm) and product species. Thermodynamically, dimethyl ether processed with air and steam generates hydrogen-rich fuel-cell feeds; however, the hydrogen concentration is less than that for pure DME steam reforming. Results of the thermodynamic processing of dimethyl ether indicate the complete conversion of dimethyl ether to hydrogen, carbon monoxide and carbon dioxide for temperatures greater than 200 °C, oxygen-to-carbon ratios greater than 0.00 and steam-to-carbon ratios greater than 1.25 at atmospheric pressure (P = 1 atm). Increasing the operating pressure has negligible effects on the hydrogen content. Thermodynamically, dimethyl ether can produce concentrations of hydrogen and carbon monoxide of 52% and 2.2%, respectively, at a temperature of 300 °C, and oxygen-to-carbon ratio of 0.40, a pressure of 1 atm and a steam-to-carbon ratio of 1.50. The order of thermodynamically stable products (excluding H 2, CO, CO 2, DME, NH 3 and H 2O) in decreasing mole fraction is methane, ethane, isopropyl alcohol, acetone, n-propanol, ethylene, ethanol and methyl-ethyl ether; trace amounts of formaldehyde, formic acid and methanol are observed. Ammonia and hydrogen cyanide are also thermodynamically favored products. Ammonia is favored at low temperatures in the range of oxygen-to-carbon ratios of 0.40-2.50 regardless of the steam-to-carbon ratio employed. The maximum ammonia content (i.e., 40%) occurs at an oxygen-to-carbon ratio of 0.40, a steam-to-carbon ratio of 1.00 and a temperature of 100 °C. Hydrogen cyanide is favored at high temperatures and low oxygen-to-carbon ratios with a maximum of 3.18% occurring at an oxygen-to-carbon ratio of 0.40 and a steam-to-carbon ratio of 0.00 in the temperature range of 400 °C-500 °C. Increasing the system pressure shifts the equilibrium toward ammonia and hydrogen cyanide.

Prayon process for wet acid purification

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

Davister, A.; Peeterbroeck, M.

Described is a process developed in Belgium which enables the upgrading technical phosphoric acid to feed and food grades. After laboratory and pilot tests, Prayon developed and patented a solvent extraction process using a mixture of di-isopropyl ether and tributyl phosphate as solvent. The purified phosphoric acid obtained complies with the quality requirements of the market and can be used for metal treatments, in the manufacture of pure phosphates, for cattle feed, by the fermentation industry, for beverages, etc. Among the advantages of this process are its simplicity of operation, its low power consumption, and minimal environmental pollution. Extensive technologicalmore » data are given.« less

Analysis of carvedilol enantiomers in human plasma using chiral stationary phase column and liquid chromatography with tandem mass spectrometry.

PubMed

Poggi, Josiane Cristófani; Da Silva, Flávia Garcez; Coelho, Eduardo Barbosa; Marques, Maria Paula; Bertucci, Carlo; Lanchote, Vera Lucia

2012-03-01

Carvedilol is an antihypertensive drug available as a racemic mixture. (-)-(S)-carvedilol is responsible for the nonselective β-blocker activity but both enantiomers present similar activity on α(1)-adrenergic receptor. To our knowledge, this is the first study of carvedilol enantiomers in human plasma using a chiral stationary phase column and liquid chromatography with tandem mass spectrometry. The method involves plasma extraction with diisopropyl ether using metoprolol as internal standard and direct separation of the carvedilol enantiomers on a Chirobiotic T® (Teicoplanin) column. Protonated ions [M + H](+) and their respective ion products were monitored at transitions of 407 > 100 for the carvedilol enantiomers and 268 > 116 for the internal standard. The quantification limit was 0.2 ng ml(-1) for both enantiomers in plasma. The method was applied to study enantioselectivity in the pharmacokinetics of carvedilol administered as a single dose of 25 mg to a hypertensive patient. The results showed a higher plasma concentration of (+)-(R)-carvedilol (AUC(0-∞) 205.52 vs. 82.61 (ng h) ml(-1)), with an enantiomer ratio of 2.48. Copyright © 2012 Wiley Periodicals, Inc.

Morphology of the D/A interface in vapor deposited bilayer organic photovoltaics

NASA Astrophysics Data System (ADS)

Erwin, Patrick; Dimitriou, Michael; Thompson, Mark E.

2017-08-01

A series of bilayer films were prepared by vacuum deposition onto Silicon substrates. These films consisted of either Si/SiO2/donor/C60 or Si/SiO2/C60/donor, where the organic films were in the 20-40 nm thick range and the donors were 7,7-difluoro-14-phenyl-7H-6l4,7l4-[1,3,2]diazaborinino[4,3-a:6,1-a']diisoindole (bDIP), copper phthalocyanine (CuPC), 3,6,11,14-tetraphenyldiindeno[1,2,3-cd:1',2',3'-lm]perylene (DBP) and 2-(4-(diphenylamino)-2,6- dihydroxyphenyl)-4-(4-(diphenyliminio)-2,6-dihydroxycyclohexa-2,5-dien-1-ylidene)-3-oxocyclobut-1-en-1-olate (DPSQ). The donors chosen here have been reported to give good power efficiencies when incorporated into bilayer photovoltaic cells with a C60 acceptor. These bilayer films were examined by neutron reflectometry to characterize the interface between the donor and C60. In the SiO2/donor/C60 films, DPSQ, CuPC, and DBP show a discrete interface with C60 while bDIP shows substantial spontaneous mixing at the interface, consistent with a donor/(donor + C60)/C60 structure, where the mixed layer is 14 nm.. In the SiO2/C60/donor films, all four donors show negligible mixing at the D/A interface consistent with a discrete D/A junction.

Ministry of Defence Main Estimates 2009-10

DTIC Science & Technology

2009-07-02

fR 2 M O G C ha ng es " 13 .7 " 13 .7 " 13 .7 0. 0 F le x C ap it al to R es ou rc e. 60 0. 0 60 0. 0...as h R el ea se 48 .9 48 .9 " 48 .9 0 0. 0 N D P B C os ts 13 2. 1 9. 5 14 1. 6 14 1. 6 0. 9 0. 9 R fR 1 T ot al 23 ,8 87 .1 11 ,6 32 .5 35 ,5 19 .6 17...rs O ut " 28 .0 " 28 .0 " 28 .0 R es er ve B id 2, 38 4. 3 42 2.

Real-Time Radio Wave Propagation for Mobile Ad-Hoc Network Emulation and Simulation Using General Purpose Graphics Processing Units (GPGPUs)

DTIC Science & Technology

2014-05-01

COST-Walfisch- Ikegami model (14) estimates the received power predominantly on the basis of frequency and distance to the transmitter. Ray-optical (15...34 # $ $ # % & ’ ( ) * + , , - . / - 0 1 2 3 4 5 6 7 7 6 8 9 : ; < = > ? @ A B C ? D E F A B G H ? E E I J K L M N O P Q R S T U V W X S Y Z O Y [ Q [ \\ W O P...a b _ c _ d _ e f ` d g h ` i j k l l m n o p k q r s t u v w w x y z

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

Some actions of substituted choline phenyl ethers, particularly of choline 2:6-xylyl ether

PubMed Central

Edge, N. D.; Mason, D. F. J.; Wyllie, J. H.

1957-01-01

Marked nicotine-like stimulant properties are possessed by choline phenyl ether and choline o-tolyl ether, and to a decreasing extent by choline 2:6-xylyl ether and choline 2:4:6-mesityl ether. The compounds all show neuromuscular blocking properties, which are of short duration and pass from mainly decamethonium-like to mainly curare-like as more methyl groups are added to the phenyl nucleus. This series of compounds also possesses muscarinic, weak anti-adrenaline and vasodilator properties, as well as long-lasting local anaesthetic effects in the two compounds tested by intradermal injection. PMID:13460236

Structural requirements and reaction pathways in dimethyl ether combustion catalyzed by supported Pt clusters.

PubMed

Ishikawa, Akio; Neurock, Matthew; Iglesia, Enrique

2007-10-31

The identity and reversibility of the elementary steps required for catalytic combustion of dimethyl ether (DME) on Pt clusters were determined by combining isotopic and kinetic analyses with density functional theory estimates of reaction energies and activation barriers to probe the lowest energy paths. Reaction rates are limited by C-H bond activation in DME molecules adsorbed on surfaces of Pt clusters containing chemisorbed oxygen atoms at near-saturation coverages. Reaction energies and activation barriers for C-H bond activation in DME to form methoxymethyl and hydroxyl surface intermediates show that this step is more favorable than the activation of C-O bonds to form two methoxides, consistent with measured rates and kinetic isotope effects. This kinetic preference is driven by the greater stability of the CH3OCH2* and OH* intermediates relative to chemisorbed methoxides. Experimental activation barriers on Pt clusters agree with density functional theory (DFT)-derived barriers on oxygen-covered Pt(111). Measured DME turnover rates increased with increasing DME pressure, but decreased as the O2 pressure increased, because vacancies (*) on Pt surfaces nearly saturated with chemisorbed oxygen are required for DME chemisorption. DFT calculations show that although these surface vacancies are required, higher oxygen coverages lead to lower C-H activation barriers, because the basicity of oxygen adatoms increases with coverage and they become more effective in hydrogen abstraction from DME. Water inhibits reaction rates via quasi-equilibrated adsorption on vacancy sites, consistent with DFT results indicating that water binds more strongly than DME on vacancies. These conclusions are consistent with the measured kinetic response of combustion rates to DME, O2, and H2O, with H/D kinetic isotope effects, and with the absence of isotopic scrambling in reactants containing isotopic mixtures of 18O2-16O2 or 12CH3O12CH3-13CH3O13CH3. Turnover rates increased with Pt cluster size, because small clusters, with more coordinatively unsaturated surface atoms, bind oxygen atoms more strongly than larger clusters and exhibit lower steady-state vacancy concentrations and a consequently smaller number of adsorbed DME intermediates involved in kinetically relevant steps. These effects of cluster size and metal-oxygen bond energies on reactivity are ubiquitous in oxidation reactions requiring vacancies on surfaces nearly saturated with intermediates derived from O2.

7-Chloro-4-[(7-chloro­quinolin-4-yl)sulfan­yl]quinoline dihydrate

PubMed Central

Wardell, James L.; Tiekink, Edward R. T.

2012-01-01

In the title thio­ether dihydrate, C18H10Cl2N2S·2H2O, the S-bound quinolinyl residues are almost orthogonal, forming a dihedral angle of 72.36 (4)°. In the crystal, the four water mol­ecules are connected via an eight-membered {⋯OH}4 synthon with each of the four pendent water H atoms hydrogen bonded to a pyridine N atom to stabilize a three-dimensional architecture. PMID:22589973

Proton affinities of hydrated molecules

NASA Astrophysics Data System (ADS)

Valadbeigi, Younes

2016-09-01

Proton affinities (PA) of non-hydrated, M, and hydrated forms, M(H2O)1,2,3, of 20 organic molecules including alcohols, ethers, aldehydes, ketones and amines were calculated by the B3LYP/6-311++G(d,p) method. For homogeneous families, linear correlations were observed between PAs of the M(H2O)1,2,3 and the PAs of the non-hydrated molecules. Also, the absolute values of the hydration enthalpies of the protonated molecules decreased linearly with the PAs. The correlation functions predicted that for an amine with PA < 1100 kJ/mol the PA(M(H2O)) is larger than the corresponding PA, while for an amine with PA > 1100 kJ/mol the PA(M(H2O)) is smaller than the PA.

Hydration of polar and nonpolar molecules at the surface of amorphous solid water

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

Souda, Ryutaro

2004-10-15

On the basis of time-of-flight secondary ion mass spectrometry, properties of amorphous solid water above the glass transition temperature (136 K) and the hydration of polar (HCOOH,C{sub 3}H{sub 7}OH) and nonpolar (C{sub 6}H{sub 14},C{sub 6}F{sub 14}) molecules on the D{sub 2}O-ice surface have been investigated. No evidence was obtained for the irreversible transition of the amorphous solid water into the crystalline phase: the self-diffusion of water molecules occurs above 140 K irrespective of the preparation temperatures of the water-ice film ranging from 15 K to 165 K, whereas the morphology of the film changes drastically at 165 K due tomore » the evolution of liquidlike water. It is also demonstrated that the change in conformation of the hydrated HCOOH molecule, as well as the occurrence of hydrophilic/hydrophobic hydration of the C{sub 3}H{sub 7}OH molecule, can be analyzed successfully from the temperature evolutions of the secondary-ion intensities. These polar molecules basically stay on the surface and tend to quench the morphological change of the water film due to the reduction of surface tension. The nonpolar C{sub 6}H{sub 14} and C{sub 6}F{sub 14} molecules readily dissolve in the D{sub 2}O layer below 100 K and dehydration of the incorporated molecules occurs at 165 K concomitantly with the evolution of the liquidlike water. It is thus concluded that the hydrophobic hydration of nonpolar molecules is intimately related to the properties of water films.« less

Thermodynamic properties of hyperbranched polymer, Boltorn U3000, using inverse gas chromatography.

PubMed

Domańska, Urszula; Zołek-Tryznowska, Zuzanna

2009-11-19

Mass-fraction activity coefficients at infinite dilution (Omega13(infinity)) of alkanes (C5-C10), cycloalkanes (C5-C8), alkenes (C5-C8), alkynes (C5-C8), aromatic hydrocarbons (benzene, toluene, ethylbenzene, o-, m-, p-xylene, thiophene), alcohols (C1-C5), water, ethers (tetrahydrofuran (THF), methyl-tert-butylether (MTBE), diethyl-, di-n-propyl-, di-n-butyl ether), and ketones (propanone, 2-pentanone, 3-pentanone, 2-hexanone, 3-hexanone, cyclopentanone) in the hyperbranched polymer, Boltorn U3000 (B-U3000), have been determined by inverse gas chromatography (IGC) using the polymer as the stationary phase. The measurements were carried out at different temperatures between 308.15 and 348.15 K. The density and thermophysical properties of polymer were described. The specific retention volume (V(g)), the Flory-Huggins interaction parameter (chi13(infinity)), the molar enthalpy of sorption (the partial molar enthalpies of solute dissolution) (Delta(s)H), the partial molar excess enthalpy at infinite dilution of the solute and polymer (DeltaH1(E,infinity)), the partial molar Gibbs excess energy at infinite dilution (DeltaG1(E,infinity)), and the solubility parameter (delta3) were calculated.

A PEROXIDASE-MEDIATED, STREPTOCOCCUS MITIS-DEPENDENT ANTIMICROBIAL SYSTEM IN SALIVA

PubMed Central

Hamon, Charles B.; Klebanoff, Seymour J.

1973-01-01

H2O2 formation by Streptococcus mitis was measured by the catalase-dependent conversion of [14C]formate to 14CO2 ; it was optimal at pH 6.0–6.5 and required glucose. The H2O2 formed by S. mitis could be employed as a component of an antimicrobial system that also included lactoperoxidase (LPO) and either iodide or thiocyanate ions in the concentrations present in saliva. The antimicrobial effect of the LPO-iodide-S. mitis system was measured by the decrease in the viable cell count of the target organisms (Escherichia coli, Staphylococcus aureus, Candida tropicalis). The antimicrobial effect of the LPO-thiocyanate-S. mitis system was measured by the decrease in the rate of growth or the rate of uptake of [14C]valine by the target organisms (E. coli, S. aureus). Mixed or parotid saliva could replace LPO and thiocyanate ions in the S. mitis-dependent inhibition of bacterial growth and valine uptake. The presence in saliva of a peroxidase-mediated, antimicrobial system dependent on microbial metabolism for H2O2 and its role as a natural host defense mechanism are considered. PMID:4685704

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.

Community Noise Exposure Resulting from Aircraft Operations. Volume 5. Acoustic Data on Air Force Propeller Aircraft

DTIC Science & Technology

1978-02-01

6 .- 6 a . I a- S 0 I I C3 uI nm0 14 * N N 𔃾 nInA󈧒 C3 f6 - ~ S C3S00 0c h )4 a1 SnI S i LU 14 0 I0 w 1 .- 4 1- pejz I C SW4 - #N0Wa*% 0( IW -W~ x...m #a CAC3 * DtoKIDft4 lp 3 I f6 . lt-C3 lat *0- IL 0 19 9 9 999 **9 U% .49 9999 I (A o3 0-1.1 N N .80* us-Ia. , NF0In m UN O.4 " 0.2 4% 1 I 1 WI "i I4...G OPIA0 0* N.4C " DI 0.3, 0=6s (A 6 4 6 4 .4 *L 7 I I f6 1 0 CLx 2 W N M9 0% *ON 40 MNca.4t C3 GON 00’p.*!fU ON N I o x11 j eS .4 4 I 6& ILI’N I L5

Electrochemical and diffusional insights of combustion synthesized SrLi2Ti6O14 negative insertion material for Li-ion Batteries

NASA Astrophysics Data System (ADS)

Dayamani, Allumolu; Shinde, Ganesh S.; Chaupatnaik, Anshuman; Rao, R. Prasada; Adams, Stefan; Barpanda, Prabeer

2018-05-01

Solvothermal synthetic routes can provide energy-savvy platforms to fabricate battery anode materials involving relatively milder annealing steps vis-à-vis the conventional solid-state synthesis. These energy efficient routes in turn restrict aggressive grain growth to form nanoscale particles favouring efficient Li+ diffusion. Here, we report an economic solution combustion synthesis of SrLi2Ti6O14 anode involving nitrate-urea complexation with a short annealing duration of only 2 h (900 °C). Rietveld refinement confirms the phase purity of target product assuming an orthorhombic framework (Cmca symmetry). It delivers reversible capacity of ∼125 mAh.g-1 at a rate of C/20 involving a 1.38 V Ti4+/Ti3+ redox activity with excellent rate kinetics and cycling stability. Bond valence site energy (BVSE) calculations gauge SrLi2Ti6O14 to be an anisotropic 3D Li+ ion conductor with the highest ionic conductivity along the c direction. The electrochemical and diffusional pathways have been elucidated for combustion prepared SrLi2Ti6O14 as an efficient and safe negative electrode candidate for Li-ion batteries.

N′-[(E)-3-Chloro-2-fluoro­benzyl­idene]-6-methyl­nicotinohydrazide monohydrate

PubMed Central

Fun, Hoong-Kun; Quah, Ching Kheng; Shyma, P. C.; Kalluraya, Balakrishna; Vidyashree, J. H. S.

2012-01-01

The title compound, C14H11ClFN3O·H2O, exists in an E conformation with respect to the N=C bond. The pyridine ring forms a dihedral angle of 5.00 (9)° with the benzene ring. In the crystal, the ketone O atom accepts one O—H⋯O and one C—H⋯O hydrogen bond, the water O atom accepts one N—H⋯O and two C—H⋯O hydrogen bonds and the pyridine N atom accepts one O—H⋯N hydrogen bond, forming layers parallel to the ab plane. PMID:22798798

Optimization of soxhlet extraction and physicochemical analysis of crop oil from seed kernel of Feun Kase (Thevetia peruviana)

NASA Astrophysics Data System (ADS)

Suwari, Kotta, Herry Z.; Buang, Yohanes

2017-12-01

Optimizing the soxhlet extraction of oil from seed kernel of Feun Kase (Thevetia peruviana) for biodiesel production was carried out in this study. The solvent used was petroleum ether and methanol, as well as their combinations. The effect of three factors namely different solvent combinations (polarity), extraction time and extraction temperature were investigated for achieving maximum oil yield. Each experiment was conducted in 250 mL soxhlet apparatus. The physicochemical properties of the oil yield (density, kinematic viscosity, acid value, iodine value, saponification value, and water content) were also analyzed. The optimum conditions were found after 4.5 h with extraction time, extraction temperature at 65 oC and petroleum ether to methanol ratio of 90 : 10 (polarity index 0.6). The oil extract was found to be 51.88 ± 3.18%. These results revealed that the crop oil from seed kernel of Feun Kase (Thevetia peruviana) is a potential feedstock for biodiesel production.

Structure elucidation and chemical synthesis of stigmolone, a novel type of prokaryotic pheromone

PubMed Central

Hull, William E.; Berkessel, Albrecht; Plaga, Wulf

1998-01-01

Approximately 2 μmol of a novel prokaryotic pheromone, involved in starvation-induced aggregation and formation of fruiting bodies by the myxobacterium Stigmatella aurantiaca, were isolated by a large-scale elution procedure. The pheromone was purified by HPLC, and high-resolution MS, IR, 1H-NMR, and 13C-NMR were used to identify the active substance as the hydroxy ketone 2,5,8-trimethyl-8-hydroxy-nonan-4-one, which has been named stigmolone. The analysis was complicated by a solvent-dependent equilibrium between stigmolone and the cyclic enol-ether 3,4-dihydro-2,2,5-trimethyl-6-(2-methylpropyl)-2H-pyran formed by intramolecular nucleophilic attack of the 8-OH group at the ketone C4 followed by loss of H2O. Both compounds were synthesized chemically, and their structures were confirmed by NMR analysis. Natural and synthetic stigmolone have the same biological activity at ca. 1 nM concentration. PMID:9736725

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.

3-(4-Hy­droxy­phen­yl)-7-meth­oxy­chroman-4-one monohydrate

PubMed Central

Xiao, Zhu-Ping; Peng, Zhu-Yun; Luo, Qun; Wu, Ying; Yang, Ye-Ling

2011-01-01

In the title compound, C16H14O4·H2O, the dihedral angle betwen the benzene rings is 71.4 (6)°. The pyran ring is in a sofa conformation. In the crystal, O—H⋯O hydrogen bonds connect the components into a two-dimensional network parallel to (010), incorporating C 2 2(4) and C 2 2(11) chains. In addition, weak C—H⋯O, C—H⋯π and π–π stacking inter­actions [centroid–centroid distance = 3.768 (2) Å] are present. PMID:22199730

Abundances of ethylene oxide and acetaldehyde in hot molecular cloud cores

NASA Technical Reports Server (NTRS)

Nummelin, A.; Dickens, J. E.; Bergman, P.; Hjalmarson, A.; Irvine, W. M.; Ikeda, M.; Ohishi, M.

1998-01-01

We have searched for millimetre-wave line emission from ethylene oxide (c-C2H4O) and its structural isomer acetaldehyde (CH3CHO) in 11 molecular clouds using SEST. Ethylene oxide and acetaldehyde were detected through multiple lines in the hot cores NGC 6334F, G327.3-0.6, G31.41+0.31, and G34.3+0.2. Acetaldehyde was also detected towards G10.47+0.03, G322.2+0.6, and Orion 3'N, and one ethylene oxide line was tentatively detected in G10.47+0.03. Column densities and rotational excitation temperatures were derived using a procedure which fits the observed line intensifies by finding the minimum chi 2-value. The resulting rotational excitation temperatures of ethylene oxide and acetaldehyde are in the range 16-38 K, indicating that these species are excited in the outer, cooler parts of the hot cores or that the excitation is significantly subthermal. For an assumed source size of 20", the deduced column densities are (0.6-1)x10(14) cm-2 for ethylene oxide and (2-5)x10(14) cm-2 for acetaldehyde. The fractional abundances with respect to H2 are X[c-C2H4O]=(2-6)xl0(-10), and X[CH3CHO]=(0.8-3)x10(-9). The ratio X[CH3CHO]/X[c-C2H4O] varies between 2.6 (NGC 6334F) and 8.5 (G327.3-0.6). We also detected and analysed multiple transitions of CH3OH, CH3OCH3, C2H5OH, and HCOOH. The chemical, and possibly evolutionary, states of NGC 6334F, G327.3-0.6, G31.41+0.31, and G34.3+0.2 seem to be very similar.

A series of substituted (2E)-3-(2-fluoro-4-phenoxyphenyl)-1-phenylprop-2-en-1-ones.

PubMed

Chopra, Deepak; Mohan, T P; Vishalakshi, B; Row, T N Guru

2007-12-01

In the molecular structures of a series of substituted chalcones, namely (2E)-3-(2-fluoro-4-phenoxyphenyl)-1-phenylprop-2-en-1-one, C21H15FO2, (I), (2E)-3-(2-fluoro-4-phenoxyphenyl)-1-(4-fluorophenyl)prop-2-en-1-one, C21H14F2O2, (II), (2E)-1-(4-chlorophenyl)-3-(2-fluoro-4-phenoxyphenyl)prop-2-en-1-one, C21H14ClFO2, (III), (2E)-3-(2-fluoro-4-phenoxyphenyl)-1-(4-methylphenyl)prop-2-en-1-one, C22H17FO2, (IV), and (2E)-3-(2-fluoro-4-phenoxyphenyl)-1-(4-methoxyphenyl)prop-2-en-1-one, C22H17FO3, (V), the configuration of the keto group with respect to the olefinic double bond is s-cis. The molecules pack utilizing weak C-H...O and C-H...pi intermolecular contacts. Identical packing motifs involving C-H...O interactions, forming both chains and dimers, along with C-H...pi dimers and pi-pi aromatic interactions are observed in the fluoro, chloro and methyl derivatives.

Safety in the SEM laboratory--1981 update

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

Bance, G.N.; Barber, V.C.; Sholdice, J.A.

1981-01-01

The article reviews recent information on hazards as they relate to safety in SEM laboratories. The first section lists the safety equipment that should be available in a SEM laboratory. Flammable and combustible liquids are discussed, and particular warnings are given concerning the fire and explosion risks associated with diethyl ether and diisopropyl ether. The possible hazards associated with electrical equipment, and the risk of X-ray emissions from EM's are briefly outlined. The hazards associated with acute and chronic toxicity of chemicals used in the EM laboratory are discussed. The need to reduce exposure to a growing list of recognizablemore » hazardous chemicals is emphasized. This reduction can be accomplished by more extensive use of functioning fume hoods, and the use of more appropriate and effective protective gloves. Allergies and the hazards of dangerous pathogens in the SEM laboratory are discussed. The explosion and other hazards associated with cryogens, vacuum evaporators, critical point dryers, and compressed gas cylinders are emphasized.« less

Rapid Detection and Isolation of Escherichia coli O104:H4 from Milk Using Monoclonal Antibody-coated Magnetic Beads

PubMed Central

Luciani, Mirella; Di Febo, Tiziana; Zilli, Katiuscia; Di Giannatale, Elisabetta; Armillotta, Gisella; Manna, Laura; Minelli, Fabio; Tittarelli, Manuela; Caprioli, Alfredo

2016-01-01

Monoclonal antibodies (MAbs) specific for the lipopolysaccharide (LPS) of Escherichia coli O104:H4 were produced by fusion of Sp2/O-Ag-14 mouse myeloma cells with spleen cells of Balb/c mice, immunized with heat-inactivated and sonicated E. coli O104:H4 bacterial cells. Four MAbs specific for the E. coli O104:H4 LPS (1E6G6, 1F4C9, 3G6G7, and 4G10D2) were characterized and evaluated for the use in a method for the detection of E. coli O104:H4 in milk samples that involves antibody conjugation to magnetic microbeads to reduce time and increase the efficiency of isolation. MAb 1E6G6 was selected and coupled to microbeads, then used for immuno-magnetic separation (IMS); the efficiency of the IMS method for E. coli O104:H4 isolation from milk was evaluated and compared to that of the EU RL VTEC conventional culture-based isolation procedure. Milk suspensions also containing other pathogenic bacteria that could potentially be found in milk (Campylobacter jejuni, Listeria monocytogenes, and Staphylococcus aureus) were also tested to evaluate the specificity of MAb-coated beads. Beads coated with MAb 1E6G6 showed a good ability to capture the E. coli O104:H4, even in milk samples contaminated with other bacteria, with a higher number of E. coli O104:H4 CFU reisolated in comparison with the official method (121 and 41 CFU, respectively, at 103 E. coli O104:H4 initial load; 19 and 6 CFU, respectively, at 102 E. coli O104:H4 initial load; 1 and 0 CFU, respectively, at 101 E. coli O104:H4 initial load). The specificity was 100%. PMID:27379071

Evolution of Functional Groups during Pyrolysis Oil Upgrading

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

Stankovikj, Filip; Tran, Chi-Cong; Kaliaguine, Serge

In this paper, we examine the evolution of functional groups (carbonyl, carboxyl, phenol, and hydroxyl) during stabilization at 100–200 °C of two typical wood derived pyrolysis oils from BTG and Amaron in a batch reactor over Ru/C catalyst for 4h. An aqueous and an oily phase were obtained. The content of functional groups in both phases were analyzed by GC/MS, 31P-NMR, 1H-NMR, elemental analysis, KF titration, carbonyl groups by Faix, Folin – Ciocalteu method and UV-Fluorescence. The consumption of hydrogen was between 0.007 and 0.016 g/g oil, and 0.001-0.020 g of CH4/g of oil, 0.005-0.016 g of CO2/g oil andmore » 0.03-0.10 g H2O/g oil were formed. The content of carbonyl, hydroxyl, and carboxyl groups in the volatile GC-MS detectable fraction decreased (80, 65, and ~70% respectively), while their behavior in the total oil and hence in the non-volatile fraction was more complex. The carbonyl groups initially decreased having minimum at ~125-150°C and then increased, while the hydroxyl groups had reversed trend. This might be explained by initial hydrogenation of the carbonyl groups to form hydroxyls, followed by continued dehydration reactions at higher temperatures that may increase their content. The 31P-NMR was on the limit of its sensitivity for the carboxylic groups to precisely detect changes in the non-volatile fraction, however the more precise titration method showed that the concentration of carboxylic groups in the non-volatile fraction remains constant with increased stabilization temperature. The UV-Fluorescence results show that repolymerization increases with temperature. ATR-FTIR method coupled with deconvolution of the region between 1490 and 1850 cm-1 showed to be a good tool for following the changes in carbonyl groups and phenols of the stabilized pyrolysis oils. The deconvolution of the IR bands around 1050 and 1260 cm-1 correlated very well with the changes in the 31P-NMR silent O groups (likely ethers). Most of the H2O formation could be explained from the significant reduction of these silent O groups (from 12% in the fresh oils, to 6 to 2% in the stabilized oils) most probably belonging to ethers.« less

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.

Group 13 ligand supported heavy-metal complexes: first structural evidence for gallium-lead and gallium-mercury bonds.

PubMed

Prabusankar, Ganesan; Gemel, Christian; Winter, Manuela; Seidel, Rüdiger W; Fischer, Roland A

2010-05-25

Heavy-metal complexes of lead and mercury stabilized by Group 13 ligands were derived from the oxidative addition of Ga(ddp) (ddp=HC(CMeNC(6)H(3)-2,6-iPr(2))(2), 2-diisopropylphenylamino-4-diisopropyl phenylimino-2-pentene) with corresponding metal precursors. The reaction of Me(3)PbCl and Ga(ddp) afforded compound [{(ddp)Ga(Cl)}PbMe(3)] (1) composed of Ga-Pb(IV) bonds. In addition, the monomeric plumbylene-type compound [{(ddp)Ga(OSO(2)CF(3))}(2)Pb(thf)] (2a) with an unsupported Ga-Pb(II)-Ga linkage was obtained by the reaction of [Pb(OSO(2)CF(3))(3)] with Ga(ddp) (2 equiv). Compound 2a falls under the rare example of a discrete plumbylene-type compound supported by a nonclassical ligand. Interesting structural changes were observed when [Pb(OSO(2)CF(3))(3)]2.H(2)O was treated with Ga(ddp) in a 1:2 ratio to yield [{(ddp)Ga(mu-OSO(2)CF(3))}(2)(OH(2))Pb] (2b) at below -10 degrees C. Compound 2b consists of a bent Ga-Pb-Ga backbone with a bridging triflate group between the Ga-Pb bond and a weakly interacting water molecule at the gallium center. Similarly, the reaction of mercury thiolate Hg(SC(6)F(5)) with Ga(ddp) (2 equiv) produced the bimetallic homoleptic compounds anti-[{(ddp)Ga(SC(6)F(5))}(2)Hg] (3a) and gauche-[{(ddp)Ga(SC(6)F(5))}(2)Hg] (3b), respectively, with a linear Ga-Hg-Ga linkage. Compounds 1-3 were structurally characterized and these are the first examples of compounds comprised of Ga-Pb(II), Ga-Pb(IV), and Ga-Hg bonds.

Evaporation Rates of Chemical Warfare Agents using 5 CM Wind Tunnels. 5. VX From Sand and Concrete

DTIC Science & Technology

2010-12-01

1 .9 ɝ > UJ Q 2 o o i II i E r tn r m v en *• A i- 8 3 3 as s« x1 c a> o c o O § > (%) Bumieuiou lueSy 8 i« r ^ JCi ...301 2.4 2.8 42 405 8.81 87.1 UKSand 93 194 2.0 2.1 42 405 39.82 92.1 UKSand 234 300 2.4 2.7 10 405 0.87 131 SS 18 58 1.3 1.4 10 18 0.95 83.2 SS 4...3c082 sand H 620 2.79 2.82 35.2 182 1.5 8.7 3c081 sand H 131 2.12 2.44 35.3 1SI 1.5 1.0 3c 154 sand H 580 2.76 2.69 35.3 181 1.5 6.1 3c093 sand H

An Investigation of Long Term Orbits About the Planet Mars Using a Dynamic Atmosphere Model

DTIC Science & Technology

1989-12-01

O ( c IT1 I,5")) Figure 1.2: Ionosphere...20.1272 2TC - Met*t210 | ’K 40 - Ix cl o ~ /2-. o 6 230 220Z- \\AW - Ii Z10 - A €, c , , , , zoo- ’, I ,, O - %%" ISIO- %% 170- U Figure 1.4: Atmospheric...sini +’I-e2 R n ’ C ’. dk -_ -e2 R + h coti R - k P’yI-e 2 R (.1.1.4d) dt na- h na2it-e2 i haS O r)LN d121 IR (. .1. 4e) dt na2 sini il-e2 i dLN

The interaction between ketamine and some crown ethers in common organic solvents studied by NMR: The effect of donating atoms and ligand structure

NASA Astrophysics Data System (ADS)

Chekin, Fereshteh; Bordbar, Maryam; Fathollahi, Yaghoub; Alizadeh, Naader

2006-02-01

1H NMR spectroscopy was used to investigate the stoichiometry and stability of the drug ketamine cation complexes with some crown ethers, such as 15-crown-5 (15C5), aza-15-crown-5 (A15C5), 18-crown-6 (18C6), aza-18-crown-6 (A18C6), diaza-18-crown-6 (DA18C6), dibenzyl-diaza-18-crown-6 (DBzDA18C6) and cryptant [2,2,2] (C222) in acetonitrile (AN), dimethylsulfoxide (DMSO) and methanol (MeOH) at 27 °C. In order to evaluate the formation constants of the ketamine cation complexes, the CH 3 protons chemical shift (on the nitrogen atom of ketamine) was measured as function of ligand/ketamine mole ratio. The formation constant of resulting complexes were calculated by the computer fitting of chemical shift versus mole ratio data to appropriate equations. A significant chemical shift variation was not observed for 15C5 and 18C6. The stoichiometry of the mono aza and diaza ligands are 1:1 and 1:2 (ligand/ketamine), respectively. In all of the solvents studied, DA18C6 formed more stable complexes than other ligands. The solvent effect on the stability of these complexes is discussed.

An ether -à-go-go K+ current, Ih-eag, contributes to the hyperpolarization of human fusion-competent myoblasts

PubMed Central

Bijlenga, Philippe; Occhiodoro, Teresa; Liu, Jian-Hui; Bader, Charles R; Bernheim, Laurent; Fischer-Lougheed, Jacqueline

1998-01-01

Two early signs of human myoblast commitment to fusion are membrane potential hyperpolarization and concomitant expression of a non-inactivating delayed rectifier K+ current, IK(NI). This current closely resembles the outward K+ current elicited by rat ether-à-go-go (r-eag) channels in its range of potential for activation and unitary conductance.It is shown that activation kinetics of IK(NI), like those of r-eag, depend on holding potential and on [Mg2+]o, and that IK(NI), like r-eag, is reversibly inhibited by a rise in [Ca2+].Forced expression of an isolated human ether-à-go-go K+ channel (h-eag) cDNA in undifferentiated myoblasts generates single-channel and whole-cell currents with remarkable similarity to IK(NI).h-eag current (Ih-eag) is reversibly inhibited by a rise in [Ca2+]i, and the activation kinetics depend on holding potential and [Mg2+]o.Forced expression of h-eag hyperpolarizes undifferentiated myoblasts from −9 to −50 mV, the threshold for the activation of both Ih-eag and IK(NI). Similarly, the higher the density of IK(NI), the more hyperpolarized the resting potential of fusion-competent myoblasts.It is concluded that h-eag constitutes the channel underlying IK(NI) and that it contributes to the hyperpolarization of fusion-competent myoblasts. To our knowledge, this is the first demonstration of a physiological role for a mammalian eag K+ channel. PMID:9763622

Tautomeric properties, conformations and structure of N-(2-hydroxy-5-chlorophenyl) salicylaldimine

NASA Astrophysics Data System (ADS)

Elmali, A.; Kabak, M.; Kavlakoglu, E.; Elerman, Y.; Durlu, T. N.

1999-11-01

The crystal structure of N-(2-hydroxy-5-chlorophenyl) salicylaldimine (C 13H 10NO 2Cl) was determined by X-ray analysis. It crystallizes orthorhombic space group P2 12 12 1 with a=12.967(2) Å, b=14.438(3) Å, c=6.231(3) Å, V=1166.5(6) Å 3, Z=4, Dc=1.41 g cm -3 and μ(MoK α)=0.315 mm -1. The title compound is thermochromic and the molecule is nearly planar. Both tautomeric forms (keto and enol forms in 68(3) and 32(3)%, respectively) are present in the solid state. The molecules contain strong intramolecular hydrogen bonds, N1-H1⋯O1/O2 (2.515(1) and 2.581(2) Å) for the keto form and O1-H01⋯N1 for the enol one. There is also strong intermolecular O2-H⋯O1 hydrogen bonding (2.599(2) Å) between neighbouring molecules. Minimum energy conformations AM1 were calculated as a function of the three torsion angles, θ1(N1-C7-C6-C5), θ2(C8-N1-C7-C6) and θ3(C9-C8-N1-C7), varied every 10°. Although the molecule is nearly planar, the AM1 optimized geometry of the title compound is not planar. The non-planar conformation of the title compound corresponding to the optimized X-ray structure is the most stable conformation in all calculations.

Three polymorphs of an inclusion compound of 2,2'-(disulfanediyl)dibenzoic acid and trimethylamine.

PubMed

Yang, Yunxia; Li, Lihua; Zhang, Li; Dong, Wenjing; Ding, Keying

2016-12-01

Polymorphism is the ability of a solid material to exist in more than one form or crystal structure and this is of interest in the fields of crystal engineering and solid-state chemistry. 2,2'-(Disulfanediyl)dibenzoic acid (also called 2,2'-dithiosalicylic acid, DTSA) is able to form different hydrogen bonds using its carboxyl groups. The central bridging S atoms allow the two terminal arene rings to rotate freely to generate various hydrogen-bonded linking modes. DTSA can act as a potential host molecule with suitable guest molecules to develop new inclusion compounds. We report here the crystal structures of three new polymorphs of the inclusion compound of DTSA and trimethylamine, namely trimethylazanium 2-[(2-carboxyphenyl)disulfanyl]benzoate 2,2'-(disulfanediyl)dibenzoic acid monosolvate, C 3 H 10 N + ·C 14 H 9 O 4 S 2 - ·C 14 H 10 O 4 S 2 , (1), tetrakis(trimethylazanium) bis{2-[(2-carboxyphenyl)disulfanyl]benzoate} 2,2'-(disulfanediyl)dibenzoate 2,2'-(disulfanediyl)dibenzoic acid monosolvate, 4C 3 H 10 N + ·2C 14 H 9 O 4 S 2 - ·C 14 H 8 O 4 S 2 2- ·C 14 H 10 O 4 S 2 , (2), and trimethylazanium 2-[(2-carboxyphenyl)disulfanyl]benzoate, C 3 H 10 N + ·C 14 H 9 O 4 S 2 - , (3). In the three polymorphs, DTSA utilizes its carboxyl groups to form conventional O-H...O hydrogen bonds to generate different host lattices. The central N atoms of the guest amine molecules accept H atoms from DTSA molecules to give the corresponding cations, which act as counter-ions to produce the stable crystal structures via N-H...O hydrogen bonding between the host acid and the guest molecule. It is noticeable that although these three compounds are composed of the same components, the final crystal structures are totally different due to the various configurations of the host acid, the number of guest molecules and the inducer (i.e. ancillary experimental acid).

The Tritiated Water Skin Barrier Integrity Test: Considerations for Acceptance Criteria with and Without 14C-Octanol.

PubMed

Lehman, Paul A; Beatch, Kacie; Raney, Sam G; Franz, Thomas J

2017-01-01

A study was designed to assess barrier integrity simultaneously using separate compounds (probes) for polar and non-polar pathways through the skin, 3 H 2 O and 14 C-octanol, respectively; and to determine whether the two probe approach could better define barrier integrity. A 5-min dose of water containing 3 H 2 O and 14 C -octanol was applied to ex vivo human skin mounted in Franz diffusion cells. The receptor solution was sampled at 30 min, analyzed for 3 H and 14 C content, and the correlation between water and octanol absorption was determined by statistical tests suitable for non-normally distributed data. This study was conducted on skin from 37 donors with from 3 to 30 replicate skin sections per donor (a total of 426 sections). The correlation between 3 H 2 O and 14 C-octanol absorption was low (Pearson correlation coefficient = 0.3485). The 3 H 2 O absorption cutoff used in this study to select for a normal skin barrier rejected some sections in which 14 C-octanol absorption was within normal limits and accepted others in which 14 C-octanol absorption was abnormally high. The converse was true for 3 H 2 O absorption when the 14 C-octanol-based cutoff was used. The results of the 3 H 2 O test or of similar tests that primarily assess the permeability of polar pathways through the skin may not necessarily provide information relevant to the absorption of highly lipophilic compounds. Octanol, or another molecule that more closely matches the physicochemical attributes of the test compound, may characterize properties of the skin barrier that are more relevant to compounds of low water solubility.

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.

Synthesis, structure and reactivity of rare-earth metallacarborane alkyls [η(1):η(5)-O(CH2)2C2B9H9]Ln(σ:η(1)-CH2C6H4-o-NMe2)(THF)2.

PubMed

Yang, Jingying; Xie, Zuowei

2015-04-14

Rare-earth metallacarborane alkyls can be stabilized by the incorporation of a functional sidearm into both π and σ ligands. Reaction of [Me3NH][7,8-O(CH2)2-7,8-C2B9H10] with one equiv. of Ln(CH2C6H4-o-NMe2)3 gave metallacarborane alkyls [η(1):η(5)-O(CH2)2C2B9H9]Ln(σ:η(1)-CH2C6H4-o-NMe2)(THF)2 (Ln = Y (), Gd (), Er ()) via alkane elimination. They represent the first examples of rare-earth metallacarborane alkyls. Treatment of with RN[double bond, length as m-dash]C[double bond, length as m-dash]NR (R = Cy, (i)Pr) or 2-benzoylpyridine afforded the corresponding mono-insertion products [η(1):η(5)-O(CH2)2C2B9H9]Y[η(2)-(RN)2C(CH2C6H4-o-NMe2)](DME) (R = Cy (), (i)Pr ()) or [η(1):η(5)-O(CH2)2C2B9H9]Y[C5H4NC(Ph)(CH2C6H4-o-NMe2)O](THF)2 (), respectively. Complex also reacted with ArNCO or ArNC (Ar = 2,6-diisopropylphenyl, 2,6-dimethylphenyl) to give di-insertion products [η(1):η(5)-O(CH2)2C2B9H9]Y[OC([double bond, length as m-dash]NC6H3Me2)N(C6H3Me2)C(CH2C6H4-o-NMe2)O](THF)2 () or [η(1):η(5)-O(CH2)2C2B9H9]Y[C([double bond, length as m-dash]NC6H3(i)Pr2)C([double bond, length as m-dash]NC6H3(i)Pr2)(CH2C6H4-o-NMe2)](DME) (). These results showed that the reactivity pattern of the Ln-C σ bond in rare-earth metallacarborane alkyls was dependent on the nature of the unsaturated organic molecules. New complexes were characterized by various spectroscopic techniques and elemental analysis. Some were further confirmed by single-crystal X-ray analysis.

Structure and physicochemical characterization of a naproxen–picolinamide cocrystal

PubMed Central

Kerr, Hannah E.; Softley, Lorna K.; Suresh, Kuthuru; Hodgkinson, Paul; Evans, Ivana Radosavljevic

2017-01-01

Naproxen (NPX) is a nonsteroidal anti-inflammatory drug with pain- and fever-relieving properties, currently marketed in the sodium salt form to overcome solubility problems; however, alternative solutions for improving its solubility across all pH values are desirable. NPX is suitable for cocrystal formation, with hydrogen-bonding possibilities via the COOH group. The crystal structure is presented of a 1:1 cocrystal of NPX with picolinamide as a coformer [systematic name: (S)-2-(6-meth­oxy­naphthalen-2-yl)propanoic acid–pyridine-2-carbox­amide (1/1), C14H14O3·C6H6N2O]. The pharmaceutically relevant physical properties were investigated and the intrinsic dissolution rate was found to be essentially the same as that of commercial naproxen. An NMR crystallography approach was used to investigate the H-atom positions in the two crystallographically unique COOH–CONH hydrogen-bonded dimers. 1H solid-state NMR distinguished the two carboxyl protons, despite the very similar crystallographic environments. The nature of the hydrogen bonding was confirmed by solid-state NMR and density functional theory calculations. PMID:28257010

Structure and physicochemical characterization of a naproxen-picolinamide cocrystal.

PubMed

Kerr, Hannah E; Softley, Lorna K; Suresh, Kuthuru; Hodgkinson, Paul; Evans, Ivana Radosavljevic

2017-03-01

Naproxen (NPX) is a nonsteroidal anti-inflammatory drug with pain- and fever-relieving properties, currently marketed in the sodium salt form to overcome solubility problems; however, alternative solutions for improving its solubility across all pH values are desirable. NPX is suitable for cocrystal formation, with hydrogen-bonding possibilities via the COOH group. The crystal structure is presented of a 1:1 cocrystal of NPX with picolinamide as a coformer [systematic name: (S)-2-(6-methoxynaphthalen-2-yl)propanoic acid-pyridine-2-carboxamide (1/1), C 14 H 14 O 3 ·C 6 H 6 N 2 O]. The pharmaceutically relevant physical properties were investigated and the intrinsic dissolution rate was found to be essentially the same as that of commercial naproxen. An NMR crystallography approach was used to investigate the H-atom positions in the two crystallographically unique COOH-CONH hydrogen-bonded dimers. 1 H solid-state NMR distinguished the two carboxyl protons, despite the very similar crystallographic environments. The nature of the hydrogen bonding was confirmed by solid-state NMR and density functional theory calculations.

X-ray, spectroscopic and antibacterial activity studies of the 1:1 complex of lasalocid acid with 1,1,3,3-tetramethylguanidine

NASA Astrophysics Data System (ADS)

Huczyński, Adam; Janczak, Jan; Stefańska, Joanna; Rutkowski, Jacek; Brzezinski, Bogumil

2010-08-01

The crystal structure of the 1:1 complex between lasalocid acid (LAS) and 1,1,3,3-tetramethylguanidine (TMG) with one inclusion acetone molecule is studied by X-ray diffraction, FT-IR spectroscopy, 1H and 13C NMR. The complex is stabilized by three intra- and two inter-molecular hydrogen bonds formed between LAS anion and protonated TMG molecule. The NH2+ protons of the protonated TMG molecule are hydrogen bonded with the etheric oxygen atom O(6) and the hydroxyl oxygen atom O(8) of the LAS anion. The intermolecular NH⋯O hydrogen bonds are relatively long (2.933(4) Å and 2.903(4) Å). One oxygen atom of the carboxylate group is involved in a relatively strong intramolecular quasi-aromatic O(1)-H⋯O(3) hydrogen bond of 2.428(4) Å length, and the second oxygen atom in the bifurcated intramolecular relatively weak O(4)-H⋯O(2) of 2.803(4) Å and O(8)-H⋯O(2) of 2.805(4) Å hydrogen bonds. The O(4)-H⋯O(2) and O(8)-H⋯O(2) hydrogen bonds bind the ends of the LAS anion forming a pseudo-cyclic structure. The FT-IR spectra of the complex in the solid state and in the solution are comparable, thus the structures observed in the both states are also comparable. The in vitro biological tests of LAS-TMG show its good activity towards some strains of Gram-positive bacteria but this activity is lower than that of lasalocid acid.

Hybrid Fluorosilicones for Aircraft Fuel Tank Sealants. Part 4. Synthesis of Fluorocarbon and Fluorocarbon Ether Hybrid Fluorosilicone Polymers.

DTIC Science & Technology

1974-05-01

onine n oviro id i ncesay (Coidntiu d onac evesesie fluoroether SECURITY CLASIICAIO OFstuei THISer wAGE sythsie,and uRred) research~~~~~~~~ amle wer...i I. ." r;. . - 7 7 7 SECTION Table of Contents (Continued)Page b. Preparation of CHa-CH(CFa)aO(CFa),O( CFt )CH-CH* ............ 27 c. Preparation of...Photolysis of I(CFg)aO(CPs)nO(CFm)aI/Hg/ CFt .................. 32 6. Reaction of I(CFR)&O(CF,).O(CFa)s1 with Hg ..................... 33 a. 280 0C

Cation or Solvent-Induced Supermolecular Phthalocyanine Formation: Crown Ether Substituted Phthalocyanines.

DTIC Science & Technology

1987-06-01

38.) of slightly bluish green powder (Anal, see Table I). tH NMR(CDCl 3 ) 8.02(8H,s), 4.7-3.6(64H,m), - 3.41(2H,s). ZnCRPc was obtained by reaction of...J.P.; Bencosme, S.; Evitt, E., Sessler, J. Chem. Phys. 1984, 86, 161. Mialoco, C.; Giannotti, A., Maillard , P.; Momeuteau, M. Chem. Phys. Lett. 1984

International Workshop on Advances in Inorganic Fibre Technology Held in Melbourne, Australia on August 13 - 14, 1992

DTIC Science & Technology

1992-08-14

o Air -cured 0 1-Octyne-cured,/ S1-Hexyne I -cured 1 10- E C 5 011 0 L I I I 1200...1825 °C o TWS-400, 2h * TWS-400, 4h 52 INORGANIC FIBRES FOR CDMPOSITE MATERIALS A.R. BUNSELL Ecole Nationale Sup6rieure des Mines de Paris Centre des ...7stalblishm~ent in U.K. It was soon estab.li sheia -t1at .uazlit; of ?M precursor ani o temperatUra ther.:-A3_ stubilisation con iition3 are - tw.. o

Liquefaction of kraft lignin by hydrocracking with simultaneous use of a novel dual acid-base catalyst and a hydrogenation catalyst.

PubMed

Wang, Jindong; Li, Wenzhi; Wang, Huizhen; Ma, Qiaozhi; Li, Song; Chang, Hou-Min; Jameel, Hasan

2017-11-01

In this study, a novel catalyst, S 2 O 8 2- -KNO 3 /TiO 2 , which has active acidic and basic sites, was prepared and used in lignin hydrocracking with a co-catalyst, Ru/C. Ru/C is an efficient hydrogenation catalyst and S 2 O 8 2- -KNO 3 /TiO 2 is a dual catalyst, which could efficiently degrade lignin. This catalytic hydrogenation system can reduce solid products to less than 1%, while giving a high liquid product yield of 93%. Catalytic hydrocracking of kraft lignin at 320°C for 6h gave 93% liquid product with 0.5% solid product. Most of this liquid product was soluble in petroleum ether (60% of 93%), which is a clear liquid and comprises mainly of monomeric and dimeric degradation products. These results demonstrated that the combination of the two catalysts is an efficient catalyst for liquefaction of lignin, with little char formation (∼1%). This concept has the potential to produce valuable chemicals and fuels from lignin under moderate conditions. Copyright © 2017 Elsevier Ltd. All rights reserved.

A New Physical Meaning of Sommerfeld Fine Structure Constant

NASA Astrophysics Data System (ADS)

Sohrab, Siavash

2015-04-01

Identifying physical space or Casimir vacuum as a compressible tachyon fluid, Planck compressible ether, leads to stochastic definitions of Planck h = mk <λk > c and Boltzmann k = mk <νk > c constants, finite photon mass mk = (hk/c3)1/2 , amu = mk c2 = (hkc)1/2 , and modified Avogadro-Loschmidt number No = 1/(hkc)1/2 = 6.03766 x1023 mole-1 . Thus, Lorentz-FitzGerald contractions now result from compressibility of physical space and become causal (Pauli) in accordance with Poincaré-Lorentz dynamic theory of relativity as opposed to Einstein kinematic theory of relativity. At thermodynamic equilibrium he = me <λe > ve = hk = mk <λk > c = h, Compton wavelength can be expressed as λc = h/me c = (ve /c)h <λe > /(me <λe > ve) = αλe . Hence, Sommerfeld fine structure constant α is identified as the ratio of electron to photon speeds α = e2/(2ɛo hc) = ve/c = 1/137.036. The mean thermal speed of electron at equilibrium with photon gas is ve = 2.187640x106 m/s and its de Broglie wavelength is λe = 3.3250x10-10 m. Also, electron kinetic energy for oscillations in two directions < x + > and < x- > or ɛe = hνe = me ve2= kTe results in electron temperature Te = 3.15690x105 K.

1,4-Dioxane degradation characteristics of Rhodococcus aetherivorans JCM 14343.

PubMed

Inoue, Daisuke; Tsunoda, Tsubasa; Yamamoto, Norifumi; Ike, Michihiko; Sei, Kazunari

2018-06-01

Rhodococcus aetherivorans JCM 14343 can degrade 1,4-dioxane as a sole carbon and energy source. This study aimed to characterize this 1,4-dioxane degradation ability further, and assess the potential use of the strain for 1,4-dioxane removal in industrial wastewater. Strain JCM 14343 was able to degrade 1,4-dioxane inducibly, and its 1,4-dioxane degradation was also induced by tetrahydrofuran and 1,4-butanediol. The demonstration that 1,4-butanediol not only induced but also enhanced 1,4-dioxane degradation was a novel finding of this study. Although strain JCM 14343 appeared not to be an effective 1,4-dioxane degrader considering the maximum specific 1,4-dioxane degradation rate (0.0073 mg-dioxane/mg-protein/h), half saturation concentration (59.2 mg/L), and cell yield (0.031 mg-protein/mg-1,4-dioxane), the strain could degrade over 1100 mg/L of 1,4-dioxane and maintain its degradation activity at a wide range of temperature (5-40 °C) and pH (4-9) conditions. This suggests the usefulness of strain JCM 14343 in 1,4-dioxane treatment under acidic and cold conditions. In addition, 1,4-dioxane degradation experiments in the presence of ethylene glycol (EG) or other cyclic ethers revealed that 1,4-dioxane degradation by strain JCM 14343 was inhibited in the presence of other cyclic ethers, but not by EG, suggesting certain applicability of strain JCM 14343 for industrial wastewater treatment.

Enhancing Low-Temperature and Pressureless Sintering of Micron Silver Paste Based on an Ether-Type Solvent

NASA Astrophysics Data System (ADS)

Zhang, Hao; Li, Wanli; Gao, Yue; Zhang, Hao; Jiu, Jinting; Suganuma, Katsuaki

2017-08-01

Micron silver paste enables a low-temperature and pressureless sintering process by using an ether-type solvent CELTOL-IA (C x H y O z , x > 10, boiling point of approximately 200°C) for the die attachment of high-powered devices. The conductive patterns formed by the silver paste had a low electrical resistivity of 8.45 μΩ cm at 180°C. The paste also achieved a high bonding strength above 30 MPa at 180°C without the assistance of pressures. These superior performance indicators result from the favorable removal of the solvent, its thermal behavior, and its good wetting on the silver layer. The results suggest that the micron silver paste with a suitable solvent can promote the further spreading of next-generation power devices owing to its marked cost advantage and excellent performance.

Copper/carbon coated lithium sodium titanate as advanced anode material for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Wu, Kaiqiang; Lin, Xiaoting; Shao, Lianyi; Shui, Miao; Long, Nengbing; Ren, Yuanlong; Shu, Jie

2014-08-01

Core-shell Li2Na2Ti6O14@Cu/C is prepared by a preliminary formation of Li2Na2Ti6O14 by solid state reaction and a following coating process with Cu/C layer by thermal decomposition. The amorphous Cu/C coating layer reveals a thickness of 5 nm on the surface of Li2Na2Ti6O14, which improves the electronic conductivity and charge transfer rate of active materials. As a result, Li2Na2Ti6O14@Cu/C shows lower electrochemical polarization and quicker kinetic behavior compared to bare Li2Na2Ti6O14. Cycled at 50 mA g-1, Li2Na2Ti6O14@Cu/C can deliver a reversible capacity of 120.3 mAh g-1 after 50 cycles, which is much higher than the value of 96.8 mAh g-1 obtained by Li2Na2Ti6O14. Even kept at 400 mA g-1, a reversible lithium storage capacity of 76.3 mAh g-1 can be delivered by Li2Na2Ti6O14@Cu/C. The improved electrochemical properties of Li2Na2Ti6O14 are attributed to the electronic conductive Cu/C coating layer on the surface.

Supramolecular self-assemblies of beta-cyclodextrins with aromatic tethers: factors governing the helical columnar versus linear channel superstructures.

PubMed

Liu, Yu; Fan, Zhi; Zhang, Heng-Yi; Yang, Ying-Wei; Ding, Fei; Liu, Shuang-Xi; Wu, Xue; Wada, Takehiko; Inoue, Yoshihisa

2003-10-31

A series of 6-O-(p-substituted phenyl)-modified beta-cyclodextrin derivatives, i.e., 6-O-(4-bromophenyl)-beta-CD (1), 6-O-(4-nitrophenyl)-beta-CD (2), 6-O-(4-formylphenyl)-beta-CD (3), 6-phenylselenyl-6-deoxy-beta-CD (4), and 6-O-(4-hydroxybenzoyl)-beta-CD (5), were synthesized, and their inclusion complexation behavior in aqueous solution and self-assembling behavior in the solid state were comparatively studied by NMR spectroscopy, microcalorimetry, crystallography, and scanning tunneling microscopy. Interestingly, (seleno)ethers 1-4 and ester 5 displayed distinctly different self-assembling behavior in the solid state, affording a successively threading head-to-tail polymeric helical structure for the (seleno)ethers or a mutually penetrating tail-to-tail dimeric columnar channel structure for the ester. Combining the present and previous structures reported for the relevant beta-CD derivatives, we further deduce that the pivot heteroatom, through which the aromatic substituent is tethered to beta-CD, plays a critical role in determining the helix structure, endowing the 2-fold and 4-fold axes to the N/O- and S/Se-pivoted beta-CD aggregates, respectively. This means that one can control the self-assembling orientation, alignment, and helicity in the solid state by finely tuning the pivot atom and the tether length. Further NMR and calorimetric studies on the self-assembling behavior in aqueous solution revealed that the dimerization step is the key to the formation of linear polymeric supramolecular architecture, which is driven by favorable entropic contributions.

Syntheses, crystal structures and optical spectroscopy of Ln{sub 2}(SO{sub 4}){sub 3}.8H{sub 2}O (Ln=Ho, Tm) and Pr{sub 2}(SO{sub 4}){sub 3}.4H{sub 2}O

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

Kazmierczak, Karolina; Hoeppe, Henning A., E-mail: henning@ak-hoeppe.d

2011-05-15

The lanthanide sulphate octahydrates Ln{sub 2}(SO{sub 4}){sub 3}.8H{sub 2}O (Ln=Ho, Tm) and the respective tetrahydrate Pr{sub 2}(SO{sub 4}){sub 3}.4H{sub 2}O were obtained by evaporation of aqueous reaction mixtures of trivalent rare earth oxides and sulphuric acid at 300 K. Ln{sub 2}(SO{sub 4}){sub 3}.8H{sub 2}O (Ln=Ho, Tm) crystallise in space group C2/c (Z=4, a{sub Ho}=13.4421(4) A, b{sub Ho}=6.6745(2) A, c{sub Ho}=18.1642(5) A, {beta}{sub Ho}=102.006(1) A{sup 3} and a{sub Tm}=13.4118(14) A, b{sub Tm}=6.6402(6) A, c{sub Tm}=18.1040(16) A, {beta}{sub Tm}=101.980(8) A{sup 3}), Pr{sub 2}(SO{sub 4}){sub 3}.4H{sub 2}O adopts space group P2{sub 1}/n (a=13.051(3) A, b=7.2047(14) A, c=13.316(3) A, {beta}=92.55(3) A{sup 3}). The vibrationalmore » and optical spectra of Ho{sub 2}(SO{sub 4}){sub 3}.8H{sub 2}O and Pr{sub 2}(SO{sub 4}){sub 3}.4H{sub 2}O are also reported. -- Graphical abstract: In the lanthanide sulphate octahydrates the cations form slightly undulated layers. Between the layers are voids in which sulphate tetrahedra and water molecules are located. The holmium compound exhibits an Alexandrite effect. Display Omitted Highlights: {yields} Determination of the optimum conditions for the growth of single-crystals of Ln{sub 2}(SO{sub 4}){sub 3}.8H{sub 2}O (Ln=Ho, Tm) and Pr{sub 2}(SO{sub 4}){sub 3}.4H{sub 2}O. {yields} Single-crystal structure elucidation of Ln{sub 2}(SO{sub 4}){sub 3}.8H{sub 2}O (Ln=Ho, Tm) including hydrogen bonds. {yields} Single-crystal structure determination of Pr{sub 2}(SO{sub 4}){sub 3}.4H{sub 2}O including hydrogen bonds. {yields} UV-vis spectra of Ho{sub 2}(SO{sub 4}){sub 3}.8H{sub 2}O and Pr{sub 2}(SO{sub 4}){sub 3}.4H{sub 2}O recorded and interpreted: Assignation of bands and clarification of the Alexandrite effect of the Ho compound. {yields} IR and Raman spectra of Ln{sub 2}(SO{sub 4}){sub 3}.8H{sub 2}O (Ln=Ho, Tm) and Pr{sub 2}(SO{sub 4}){sub 3}.4H{sub 2}O recorded and interpreted.« less

Dynamic Solidification in Nanoconfined Water Films

DTIC Science & Technology

2010-06-16

C . Ramanujan , H. O. Ozer, and A. Oral, Phys. Rev. B, 70, 054114 (2004). [6] T. D. Li, J. P. Gao...unclassified c . THIS PAGE unclassified Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18 Water is the fundamental solvent of all...Displacement (nm) 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 D a m p in g c o e ff ic ie n t (m N s /m ) 0.0 0.5 1.0 1.5 0 1 2 3 4 5 6 7 R e la x a ti o n t

rac-6-Hydroxy-2,5,7,8-tetramethylchroman-2-carboxamide from synchrotron data

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

Brzezinski, Krzysztof; Dauter, Zbigniew; Baj, Aneta

2012-05-29

The crystal structure of the title water-soluble analogue of vitamin E, trolox amide, C{sub 14}H{sub 19}NO{sub 3}, solved and refined against synchrotron diffraction data, contains two molecules in the asymmetric unit. In both molecules, the heterocyclic ring is in a half-chair conformation. The crystal packing features a herring-bone pattern generated by N-H...O hydrogen bonds between the hydroxy and amide groups. O-H...O hydrogen bonds also occur.

Titanium isopropoxide complexes of a series of sterically demanding aryloxo based [N2O2]2- ligands as precatalysts for ethylene polymerization.

PubMed

Panda, Manas K; Kaur, Sukhdeep; Reddy, Annapureddy Rajasekhar; Shaikh, Mobin M; Butcher, Ray J; Gupta, Virendrakumar; Ghosh, Prasenjit

2010-12-07

Several titanium isopropoxide complexes [N,N'-bis(2-oxo-3-R(1)-5-R(2)-phenylmethyl)-N,N'-bis(methylene-p-R(3)-C(6)H(4))-ethylenediamine]Ti(O(i)Pr)(2) [R(1) = t-Bu, R(2) = Me, R(3) = H (1b); R(1) = R(2) = t-Bu, R(3) = H, (2b); R(1) = R(2) = Cl, R(3) = H, (3b), R(1) = t-Bu, R(2) = Me, R(3) = Cl (4b); R(1) = R(2) = t-Bu, R(3) = Cl, (5b); R(1) = R(2) = R(3) = Cl, (6b)] supported over sterically demanding aryloxy based [N(2)O(2)]H(2) ligands have been designed as precatalysts for the ethylene polymerization. Specifically, the 1b-6b complexes, when treated with methylaluminoxane (MAO) under 88 ± 0.5 psi of ethylene at 30 °C for 3 h, produced polyethylene polymers of high molecular weight (M(w) = ca. 7.2-8.3 × 10(5) g mol(-1)) having broad molecular weight distribution (PDI = ca. 13.1-14.6). The 1b-6b complexes were conveniently synthesized from the direct reaction of the [N(2)O(2)]H(2) ligands, 1a-6a, with Ti(O(i)Pr)(4) in 69-86% yield.

Solid-State Threshold Accelerometer Chip.

DTIC Science & Technology

1987-03-28

adhered to another gold surface and *welded.’ Literature on surface wear and friction effects with various surface treatments often show that gold-on...LASTING 0.1 SECONDS.i i. -- S *.I CIC ~14. MATERIAL - ALUMINUM CROSSECTION - F/;%f 蕻 n, . t -. to1 77/ - CA6 /je /24 h,6qe 3/,/.o Z#0 1/c 0, &o

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.

Dimethyl 4-[3-(4-meth­oxy­phen­yl)-1-phenyl-1H-pyrazol-4-yl]-2,6-dimethyl-1,4-dihydro­pyridine-3,5-dicarboxyl­ate dihydrate

PubMed Central

Fun, Hoong-Kun; Ooi, Chin Wei; Garudachari, B.; Shivananda, Kammasandra Nanjunda; Isloor, Arun M.

2012-01-01

In the title compound, C27H27N3O5·2H2O, the dihydro­pyridine ring adopts a flattened boat conformation. The central pyrazole ring is essentially planar [maximum deviation of 0.003 (1) Å] and makes dihedral angles of 50.42 (6) and 26.44 (6)° with the benzene rings. In the crystal, mol­ecules are linked via N—H⋯O, O—H⋯O, O—H⋯N and C—H⋯O hydrogen bonds into two-dimensional networks parallel to the bc plane. The crystal structure is further consolidated by weak C—H⋯π inter­actions. PMID:22798871

40 CFR Table 9 to Subpart Ffff of... - Soluble Hazardous Air Pollutants

Code of Federal Regulations, 2010 CFR

2010-07-01

... sulfate 77781 6. Dinitrotoluene (2,4) 121142 7. Dioxane (1,4) 123911 8. Ethylene glycol dimethyl ether 110714 9. Ethylene glycol monobutyl ether acetate 112072 10. Ethylene glycol monomethyl ether acetate...

Effect of ligand substitution on the SMM properties of three isostructural families of double-cubane Mn4Ln2 coordination clusters.

PubMed

Akhtar, Muhammad Nadeem; Lan, Yanhua; AlDamen, Murad A; Zheng, Yan-Zhen; Anson, Christopher E; Powell, Annie K

2018-03-06

Three isostructural lanthanide series with a core of MnMnLn 2 are reported. These three families have the formulae of [MnMnLn 2 (μ 4 -O) 2 (H 2 edte) 2 (piv) 6 (NO 3 ) 2 ] {no crystallization solvent, Ln = La, Ce, Pr, Nd, Eu (1-4, 6); solv = 3MeCN, Ln = Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Y (5, 7-13)}, where H 2 edte = N,N,N',N'-tetrakis(2-hydroxyethyl)ethylenediamine and piv = pivalate; [MnMnLn 2 (μ 4 -O) 2 (H 2 edte) 2 (benz) 6 (NO 3 ) 2 ], where benz = benzoate, or [MnMnLn 2 (μ 4 -O) 2 (edteH 2 ) 2 (benz) 6 (NO 3 ) 2 ]·2MeCN {Ln = Gd, Tb, Dy (14-16); and [MnMnLn 2 (μ 4 -O) 2 (edteH 2 ) 2 (piv) 8 ].solv {solv = 4MeCN, Ln = La (17); solv = 2MeCN·tol·H 2 O, Ln = Pr, Nd, Sm, Tb (18-20, 22); solv = 2MeCN·H 2 O, Ln = Gd (21). These compounds crystallize in two different systems, namely, monoclinic in the space groups P2 1 /n for 1-4, 6, and 14-16 and C2/c for 5, 7-13, 18-20, and 22 and triclinic in the space group P1[combining macron] for 17 and 21. The crystal structures of these compounds display a face-fused dicubane structure connected by different types of bridged oxygen atoms. Solid-state dc magnetic susceptibility characterization was carried out for 1-22, and fitting showed that Mn III Mn III is antiferromagnetically (AF) coupled and Mn II Mn III , Mn II Ln and Mn III Ln are weakly ferromagnetically coupled. In addition, ac measurements were carried out and showed that only 7, 15, and 22 for Tb, 8 and 16 for Dy, and 20 for Sm exhibited slow magnetization relaxation. In the case of 15, it was possible to determine the energy barrier of the slow-relaxation behavior by fitting peak temperatures to the Arrhenius law, which gave a value of U eff = 21.2 K and a pre-exponential factor of τ 0 = 4.0 × 10 -9 s.

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

Electrophilic fluorinating reagent mediated synthesis of fluorinated alpha-keto Ethers, benzil, and 6,6'-dialkoxy-2,2'-bipyridines.

PubMed

Manandhar, Sudha; Singh, Rajendra P; Eggers, Gary V; Shreeve, Jean'ne M

2002-09-06

Interactions of various fluorinated and nonfluorinated alcohols with trans-stilbene in the presence of electrophilic reagents were studied. Under neat conditions, reactions of trans-stilbene (1) with fluorinated alcohols, R(f)OH (R(f) = CF3CH2-, CFH2CH2-, CF3CF2CH2-, CF2H(CF2)3CH2-, (CF3)2CH-, (CF3)3C- (2a-f) in the presence of an electrophilic reagent, 1-(chloromethyl)-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate) (Selectfluor) or N,N-difluoro-2,2'-bipyridinium bis(tetrafluoroborate) (MEC-31), gave alpha-keto ethers (3a-f) and benzil (4) in good to moderate yields. alpha-Keto ether and benzil formation was very much dependent on the reaction time, the degree of fluorination of the alcohols, and whether a solvent such as CH3CN, DMF or DMA was utilized. In solution, alpha-keto ethers and benzil did not form. Interestingly, under neat conditions, nonfluorinated alcohols, ROH (R = CH3-, CH3CH2-, CH3CH2CH2-, CH3CH2CH2CH2-, CH3CH2CH2CH2CH2CH2-) (5g-k) did not react with trans-stilbene in the presence of MEC-31 but gave 6,6'-dialkoxy-2,2'-bipyridines (6g-k), regioselectively, in excellent isolated yields. On the other hand, fluorinated alcohols did not react with MEC-31. Reaction of MEC-31 with an excess of diethylene glycol (7) gave the bipyridine derivative (8) in 88% isolated yield. Reaction of 8 either with diethylaminosulfur trifluoride (DAST) or bis(2-methoxyethyl)aminosulfur trifluoride (Deoxofluor) readily produced the corresponding difluoro derivative (9) in 85% isolated yield. All new compounds have been characterized by spectroscopic and elemental analysis.

Friction Regimes of Water-Lubricated Diamond (111): Role of Interfacial Ether Groups and Tribo-Induced Aromatic Surface Reconstructions

NASA Astrophysics Data System (ADS)

Kuwahara, Takuya; Moras, Gianpietro; Moseler, Michael

2017-09-01

Large-scale quantum molecular dynamics of water-lubricated diamond (111) surfaces in sliding contact reveals multiple friction regimes. While water starvation causes amorphization of the tribological interface, small H2O traces are sufficient to preserve crystallinity. This can result in high friction due to cold welding via ether groups or in ultralow friction due to aromatic surface passivation triggered by tribo-induced Pandey reconstruction. At higher water coverage, Grotthuss-type diffusion and H2O dissociation yield dense H /OH surface passivation leading to another ultralow friction regime.

catena-Poly[[aqua­(1,10-phenanthroline)cobalt(II)]-μ-4,4′-(propane-1,3-diyldi­oxy)dibenzoato

PubMed Central

Shen, Su-Mei

2009-01-01

In the title compound, [Co(C17H14O6)(C12H8N2)(H2O)]n, the CoII atom is coordinated by a monodentate 4,4′-(propane-1,3-diyldi­oxy)dibenzoate (cpp) dianion, a water mol­ecule and a chelating 1,10-phenanthroline (phen) ligand. A symmetry-generated cpp ligand completes the CoN2O3 trigonal-bipyramidal geometry for the metal ion, with the N atoms occupying both equatorial and axial sites. The bridging cpp ligands form chains propagating in [110] and O—H⋯O hydrogen bonds consolidate the packing. PMID:21577702

FTIR cryospectroscopic and ab initio studies of desflurane-dimethyl ether H-bonded complexes.

PubMed

Melikova, S M; Rutkowski, K S; Rospenk, M

2017-09-05

The IR spectra of mixtures of desflurane and dimethyl ether are studied with the help of FTIR cryospectroscopy in liquefied Kr at T~118-158K. Comparative analysis of the experimental data and results of ab initio calculations show that either of the two C-H groups of desflurane is involved in heterodimer formation of comparable strengths. The blue frequency shift is found for stretching vibrations of those C-H donors which directly participate in H-bond formation. Additionally the complexes are stabilized by weaker contacts between hydrogen atoms of dimethyl ether and fluorine atoms of desflurane. Copyright © 2017 Elsevier B.V. All rights reserved.

Initial Reactivity of Linkages and Monomer Rings in Lignin Pyrolysis Revealed by ReaxFF Molecular Dynamics.

PubMed

Zhang, Tingting; Li, Xiaoxia; Guo, Li

2017-10-24

The initial conversion pathways of linkages and their linked monomer units in lignin pyrolysis were investigated comprehensively by ReaxFF MD simulations facilitated by the unique VARxMD for reaction analysis. The simulated molecular model contains 15 920 atoms and was constructed on the basis of Adler's softwood lignin model. The simulations uncover the initial conversion ratio of various linkages and their linked aryl monomers. For linkages and their linked monomer aryl rings of α-O-4, β-O-4 and α-O-4 & β-5, the C α /C β ether bond cracking dominates the initial pathway accounting for at least up to 80% of their consumption. For the linkage of β-β & γ-O-α, both the C α -O ether bond cracking and its linked monomer aryl ring opening are equally important. Ring-opening reactions dominate the initial consumption of other 4-O-5, 5-5, β-1, β-2, and β-5 linkages and their linked monomers. The ether bond cracking of C α -O and C β -O occurs at low temperature, and the aryl ring-opening reactions take place at relatively high temperature. The important intermediates leading to the stable aryl ring opening are the phenoxy radicals, the bridged five-membered and three-membered rings and the bridged six-membered and three-membered rings. In addition, the reactivity of a linkage and its monomer aryl ring may be affected by other linkages. The ether bond cracking of α-O-4 and β-O-4 linkages can activate its neighboring linkage or monomer ring through the formed phenoxy radicals as intermediates. The important intermediates revealed in this article should be of help in deepening the understanding of the controlling mechanism for producing aromatic chemicals from lignin pyrolysis.

Finishing Systems for Naval Aircraft Applications: Current Schemes and Future Trends

DTIC Science & Technology

2000-01-01

glycidyl ether (CGE) and the difunctional neopentyl glycol , diglycidyl ether (NGDE) are pictured below in Figure 7. 16 o r CH3 OH CH2- XCH-CH2--0-<Q)-C...glycidyl ether (CGE) and neopentyl glycol , diglycidyl ether (NGDE). Coatings prepared with CGE were unacceptable due to poor surface properties and

Synthesis, structure and physicochemical characterization of the hybrid material [C6H16N2O]2 SnCl6·2Cl·2H2O

NASA Astrophysics Data System (ADS)

Belhaj Salah, S.; Pereira da Silva, P. S.; Lefebvre, F.; Ben Nasr, C.; Ammar, S.; Mrad, M. L.

2017-04-01

The current study reports the chemical preparation, crystal structure, Hirshfeld surface analysis and spectroscopic characterization of the novel compound [C6H16N2O]2SnCl6·2Cl·2H2O. This compound crystallizes in the triclinic system (space group P - 1, Z = 1) with the following unit cell dimensions: a = 7.9764(9), b = 8.2703(9), c = 12.1103(14)Å, α = 84.469(6), β = 75.679(6), and γ = 64.066(5)°. The structure was solved using 3093 independent reflections down to R = 0.020. The atomic arrangement shows alternation of organic and inorganic entities. The cohesion between these entities is ensured by Nsbnd H…Cl and Osbnd H…Cl hydrogen bonds that build a three-dimensional network. The 3D Hirshfeld surfaces and the associated 2D fingerprint plots were investigated for intermolecular interactions. The 13C and 15N CP-MAS NMR spectra are in agreement with the X-ray structure. The vibrational absorption bands were identified by infrared spectroscopy. DFT calculations allowed the attribution of the IR and NMR bands. X-ray powder, XPS and UV spectrum have been carried out. The DSC profile shows that the title material exhibits dehydration at 339 K.

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.

Crystal structures of three lead(II) acetate-bridged di-amino-benzene coordination polymers.

PubMed

Geiger, David K; Parsons, Dylan E; Zick, Patricia L

2014-12-01

Poly[tris-(acetato-κ(2) O,O')(μ2-acetato-κ(3) O,O':O)tetra-kis-(μ3-acetato-κ(4) O,O':O:O')bis-(benzene-1,2-di-amine-κN)tetra-lead(II)], [Pb4(CH3COO)8(C6H8N2)2] n , (I), poly[(acetato-κ(2) O,O')(μ3-acetato-κ(4) O,O':O:O')(4-chloro-benzene-1,2-diamine-κN)lead(II)], [Pb(CH3COO)2(C6H7ClN2)] n , (II), and poly[(κ(2) O,O')(μ3-acetato-κ(4) O,O':O:O')(3,4-di-amino-benzo-nitrile-κN)lead(II)], [Pb(CH3COO)2(C7H7N3)] n , (III), have polymeric structures in which monomeric units are joined by bridging acetate ligands. All of the Pb(II) ions exhibit hemidirected coordination. The repeating unit in (I) is composed of four Pb(II) ions having O6, O6N, O7 and O6N coordination spheres, respectively, where N represents a monodentate benzene-1,2-di-amine ligand and O acetate O atoms. Chains along [010] are joined by bridging acetate ligands to form planes parallel to (10-1). (II) and (III) are isotypic and have one Pb(II) ion in the asymmetric unit that has an O6N coordination sphere. Pb2O2 units result from a symmetry-imposed inversion center. Polymeric chains parallel to [100] exhibit hydrogen bonding between the amine and acetate ligands. In (III), additional hydrogen bonds between cyano groups and non-coordinating amines join the chains by forming R 2 (2)(14) rings.

Calcium aluminates hydration in presence of amorphous SiO{sub 2} at temperatures below 90 deg. C

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

Rivas Mercury, J.M.; Turrillas, X.; Aza, A.H. de

2006-10-15

The hydration behaviour of Ca{sub 3}Al{sub 2}O{sub 6}, Ca{sub 12}Al{sub 14}O{sub 33} and CaAl{sub 2}O{sub 4} with added amorphous silica at 40, 65 and 90 deg. C has been studied for periods ranging from 1 to 31 days. In hydrated samples crystalline phases like katoite (Ca{sub 3}Al{sub 2}(SiO{sub 4}){sub 3-} {sub x} (OH){sub 4} {sub x} ) and gibbsite, Al(OH){sub 3}, were identified, likewise amorphous phases like Al(OH) {sub x} , calcium silicate hydrates, C-S-H, and calcium aluminosilicate hydrates, C-S-A-H, were identified. The stoichiometry of Ca{sub 3}Al{sub 2}(SiO{sub 4}){sub 3-} {sub x} (OH){sub 4} {sub x} (0{<=}3-x{<=}0.334), which was themore » main crystalline product, was established by Rietveld refinement of X-ray and neutron diffraction data and by transmission electron microscopy. - Graphical abstract: Katoite, Ca{sub 3}Al{sub 2}(SiO{sub 4}){sub 3-} {sub x} (OH){sub 4} {sub x} (0{<=}3-x{<=}0.334), was identified besides gibbsite, Al(OH){sub 3}, as a crystalline stable hydration products in Ca{sub 3}Al{sub 2}O{sub 6}, Ca{sub 12}Al{sub 14}O{sub 33} and CaAl{sub 2}O{sub 4} hydrated with added amorphous silica between 40 and 90 deg. C.« less

NACA Conference on Turbojet-Engine Thrust-Augmentation Research - a Compilation of the Papers Presented by NACA Staff Members

DTIC Science & Technology

1948-10-28

N . E. Harvey, Lt. Col. J. A. Hartman, E. P. Hildestad, H. L. Eolbrook, G. E, Hopkins, Lt. Comdr. L. A...velocity and diffuser efficiency on augmentation. 1041A H oo \\=> K H n w E-i O 33 1.6 1.4 E-i co !=> Pi E-i § 1.0 o 1.2 .8...xutm E"H N 1 DO E-i O £3 E-i DO £) E-H o ^ 00 :=> ex E-t Co o Is i.5 i.O .5 :.0 ,5 2 - 750 40G <C < CD-1 T Q lg 3800°

Survival of Escherichia coli O157:H7 during manufacture and storage of white brined cheese.

PubMed

Osaili, Tareq M; Al-Nabulsi, Anas A; Olaimat, Amin N; Shaker, Reyad R; Taha, Mohammad; Holley, Richard A

2014-09-01

Escherichia coli O157:H7 is a major foodborne pathogen that causes severe disease in humans. Survival of E. coli O157:H7 during processing and storage of white brined cheese was investigated. Cheeses were prepared using pasteurized milk inoculated with a 4 strain E. coli O157:H7 cocktail (7 log(10) CFU/g) with or without yogurt starter culture (Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus salivarius ssp. thermophilus) and stored in 10% or 15% NaCl brine at 10 and 21 ºC for 28 d. NaCl concentration, water activity (a(w)), pH, and numbers of E. coli O157:H7 and lactic acid bacteria (LAB) were determined in cheese and brine. E. coli O157:H7 was able to survive in cheese stored in both brines at 10 and 21 ºC regardless of the presence of starter LAB, although the latter significantly enhanced E. coli O157:H7 reduction in cheese or its brine at 10 ºC. E. coli O157:H7 numbers were reduced by 2.6 and 3.4 log(10) CFU/g in cheese stored in 10% and 15% NaCl brine, respectively, in the presence of starter LAB and by 1.4 and 2.3 log(10) CFU/g, respectively, in the absence of starter LAB at 10 ºC. The pathogen survived, but at lower numbers in the brines. The salt concentration of cheese stored in 10% brine remained about 5% during ripening, but in 15% brine, the NaCl level increased 1.6% to 8.1% (w/w) by 28 d. Values of pH and a(w) slightly decreased 1 d after exposure to brine and reached 5.5 to 6.6 and 0.88 to 0.94, respectively, in all treatments. © 2014 Institute of Food Technologists®

Crystal structure of ochraceolide A isolated from Elaeodendron trichotomum (Turcz.) Lundell

PubMed Central

Herrera-España, Angel D.; Mena-Rejón, Gonzalo J.; Hernández-Ortega, Simón; Quijano, Leovigildo; Mirón-López, Gumersindo

2017-01-01

The title compound, C30H44O3 [systematic name: 6aR,6 bR,8aS,9aR,12aR,14bR)-4,4,6a,6;b,8a,14b-hexa­methyl-12-methyl­eneicosa­hydro-3H-phenanthro[1′,2′:6,7]indeno­[2,1-b]furan-3,11(2H)-dione], is a triterpene lactone, which was isolated from di­chloro­methane extract of Elaeodendron trichotomum (Turcz.) Lundell (celastraceae) stem bark. The compound has a lupane skeleton and consists of four fused six-membered rings and two five-membered rings. In the crystal, mol­ecules are linked by weak C—H⋯O hydrogen bonds into a three-dimensional network. The configuration of ochraceolide A was proposed based on analogue compounds which belong to the lupane type. PMID:29250361

C=C bond cleavage on neutral VO3(V2O5)n clusters.

PubMed

Dong, Feng; Heinbuch, Scott; Xie, Yan; Bernstein, Elliot R; Rocca, Jorge J; Wang, Zhe-Chen; Ding, Xun-Lei; He, Sheng-Gui

2009-01-28

The reactions of neutral vanadium oxide clusters with alkenes (ethylene, propylene, 1-butene, and 1,3-butadiene) are investigated by experiments and density function theory (DFT) calculations. Single photon ionization through extreme ultraviolet radiation (EUV, 46.9 nm, 26.5 eV) is used to detect neutral cluster distributions and reaction products. In the experiments, we observe products (V(2)O(5))(n)VO(2)CH(2), (V(2)O(5))(n)VO(2)C(2)H(4), (V(2)O(5))(n)VO(2)C(3)H(4), and (V(2)O(5))(n)VO(2)C(3)H(6), for neural V(m)O(n) clusters in reactions with C(2)H(4), C(3)H(6), C(4)H(6), and C(4)H(8), respectively. The observation of these products indicates that the C=C bonds of alkenes can be broken on neutral oxygen rich vanadium oxide clusters with the general structure VO(3)(V(2)O(5))(n=0,1,2...). DFT calculations demonstrate that the reaction VO(3) + C(3)H(6) --> VO(2)C(2)H(4) + H(2)CO is thermodynamically favorable and overall barrierless at room temperature. They also provide a mechanistic explanation for the general reaction in which the C=C double bond of alkenes is broken on VO(3)(V(2)O(5))(n=0,1,2...) clusters. A catalytic cycle for alkene oxidation on vanadium oxide is suggested based on our experimental and theoretical investigations. The reactions of V(m)O(n) with C(6)H(6) and C(2)F(4) are also investigated by experiments. The products VO(2)(V(2)O(5))(n)C(6)H(4) are observed for dehydration reactions between V(m)O(n) clusters and C(6)H(6). No product is detected for V(m)O(n) clusters reacting with C(2)F(4). The mechanisms of the reactions between VO(3) and C(2)F(4)/C(6)H(6) are also investigated by calculations at the B3LYP/TZVP level.

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 the specificities of human blood group H gene-specified alpha 1,2-L-fucosyltransferase toward sulfated/sialylated/fucosylated acceptors: evidence for an inverse relationship between alpha 1,2-L-fucosylation of Gal and alpha 1,6-L-fucosylation of asparagine-linked GlcNAc.

PubMed

Chandrasekaran, E V; Jain, R K; Larsen, R D; Wlasichuk, K; Matta, K L

1996-07-09

The assembly of complex structures bearing the H determinant was examined by characterizing the specificities of a cloned blood group H gene-specified alpha 1,2-L-fucosyltransferase (FT) toward a variety of sulfated, sialylated, or fucosylated Gal beta 1,3/4GlcNAc beta- or Gal beta 1,3GalNAc alpha-based acceptor structures. (a) As compared to the basic type 2, Gal beta 1,4GlcNAc beta-(K(m) = 1.67 mM), the basic type 1 was 137% active (K(m) = 0.83 mM). (b) On C-6 sulfation of Gal, type 1 became 142.1% active and type 2 became 223.0% active (K(m) = 0.45 mM). (c) On C-6 sulfation of GlcNAc, type 2 showed 33.7% activity. (d) On C-3 or C-4 fucosylation of GlcNAc, both types 1 and 2 lost activity. (e) Type 1 showed 70.8% and 5.8% activity, respectively, on C-6 and C-4 O-methylation of GlcNAc. (f) Type 1 retained 18.8% activity on alpha 2,6-sialylation of GlcNAc. (g) Terminal type 1 or 2 of extended chain had lower activity. (h) With Gal in place of GlcNAc in type 1, the activity became 43.2%. (i) Compounds with terminal alpha 1,3-linked Gal were inactive. (j) Gal beta 1,3GalNAc alpha- (the T-hapten) was approximately 0.4-fold as active as Gal beta 1,4GlcNAc beta-. (k) C-6 sulfation of Gal on the T-hapten did not affect the acceptor activity. (l) C-6 sulfation of GalNAc decreased the activity to 70%, whereas on C-6 sulfation of both Gal and GalNAc the T-hapten lost the acceptor ability. (m) C-6 sialylation of GalNAc also led to inactivity. (n) beta 1,6 branching from GalNAc of the T-hapten by a GlcNAc residue or by units such as Gal beta 1, 4GlcNAc-, Gal beta 1,4(Fuc alpha 1,3)GlcNAc-, or 3-sulfoGal beta 1,4GlcNAc- resulted in 111.9%, 282.8%, 48.3%, and 75.3% activities, respectively. (o) The enhancement of enzyme affinity by a sulfo group on C-6 of Gal was demonstrated by an increase (approximately 5-fold) in the K(m) for Gal beta 1,4GlcNAc beta 1,6(Gal beta 1,3)GalNAc alpha-O-Bn in presence of 6-sulfoGal beta 1,- 4GlcNAc beta-O-Me (3.0 mM). (p) Among the two sites in Gal beta 1, 4GlcNAc beta 1,6(Gal beta 1,3) GalNAc alpha-O-Bn, the enzyme had a higher affinity ( > 3-fold) for the Gal linked to GlcNAc. (q) With respect to Gal beta 1,- 3GlcNAc beta-O-Bn (3.0 mM), fetuin triantennary asialo glycopeptide (2.4 mM), bovine IgG diantennary glycopeptide (2.8 mM), asialo Cowper's gland mucin (0.06 mM), and the acrylamide copolymers (0.125 mM each) containing Gal beta 1,3GlcNAc beta-, Gal beta 1,3(6-sulfo)GlcNAc beta-, Gal beta 1,3GalNAc alpha-, Gal beta 1,3Gal beta-, or Gal alpha 1,3Gal beta- units were 153.6%, 43.0%, 6.2%, 52.5%, 94.9%, 14.7%, 23.6%, and 15.6% active, respectively. (r) Fucosylation by alpha 1,2-L-FT of the galactosyl residue which occurs on the antennary structure of the bovine IgG glycopeptide was adversely affected by the presence of an alpha 1,6-L-fucosyl residue located on the distant glucosaminyl residue that is directly attached to the asparagine of the protein backbone. This became evident from the 4-fold activity of alpha 1,2-L-FT toward bovine IgG glycopeptide after approximately 5% removal of alpha 1,6-linked Fuo.

Crystal structure of choline fenofibrate (Trilipix®), (C5H14NO) (C17H14ClO4)

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

Kaduk, James A.; Zhong, Kai; Gindhart, Amy M.

2016-04-04

The crystal structure of choline fenofibrate has been solved and refined using synchrotron X-ray powder diffraction data, and optimized using density functional techniques. Choline fenofibrate crystallizes in space groupPbca(#61) witha= 12.341 03(2),b= 28.568 70(6),c= 12.025 62(2) Å,V= 4239.84(1) Å 3, andZ= 8. The hydroxyl group of the choline anion makes a strong hydrogen bond to the ionized carboxylate group of the fenofibrate anion. Together with C–H···O hydrogen bonds, these link the cations and anions into layers parallel to theac-plane. The powder pattern has been submitted to ICDD for inclusion in the Powder Diffraction File™.

Alpha List of Prime Contract Awards. Oct 92-Sep 93. FY93. (Claude Ralph - Day Francis O Co. Inc.)

DTIC Science & Technology

1994-03-01

4LLAA ( LU AC x 0 m LA (LA 0 x1 (1A)LALLCA(A( AcCA L A 0 ( tALALA01upIc (00.- U1 C(0 (D0 (0’.CD(0 (D (D (D (DW 00 0 (m (m (0CD(D0(m0w(0(20 (D0w Lo(1(0...COVcII N 44444444444 4444444444 N c04 II 44 4444 N 0041 caoacao acca 0i 0o cn I’ ID6 OOCNY 2 N4NrJNNNNNN0 NNNNNNNNNN C3 cO-4 11 L) U0 0 0 0 0 0c 0 0 0 0...0.4 .. 14൰*o0oo 00 0 0 - .4 N 4j H 4 I0cc WOO 004 INN C 10 10 100N04144443(300 t0 I0.4 ffM MN 14 100 N 0YMIn C 0 0 (1 H ma I (fl>( IIO N N NN N 0 4

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.

Crystal structures of (±)-(1SR,5SR,6SR,7SR,10SR,11SR,13RS,14SR)-13-hy-droxy-7-meth-oxy-meth-oxy-11,15,18,18-tetra-methyl-3-oxo-2,4-dioxa-tetra-cyclo-[12.3.1.0(1,5).0(6,11)]octa-dec-15-en-10-yl benzoate, its 13-epimer and 13-one derivative.

PubMed

Oishi, Takeshi; Fukaya, Keisuke; Yamaguchi, Yu; Sugai, Tomoya; Watanabe, Ami; Sato, Takaaki; Chida, Noritaka

2015-05-01

The title compounds, C29H38O8·0.25C5H12, (A), C29H38O8, (B), and C29H36O8, (C), are tetra-cyclic benzoates possessing a taxane skeleton with a fused dioxolane ring as the core structure. In the asymmetric unit of (A), there are two independent benzoate mol-ecules (A and A') and a half mol-ecule of solvent pentane disordered about an inversion center. The mol-ecular conformations of (A), (B) and (C) are similar except for the flexible meth-oxy-meth-oxy group. The cyclo-hexane, cyclo-hexene and central cyclo-octane rings adopt chair, half-chair and chair-chair (extended crown) forms, respectively. The dioxolane rings are essentially planar, while the dioxolane ring of A' is slightly twisted from the mean plane. In the crystal of (A), inter-molecular O-H⋯O, C-H⋯O and C-H⋯π inter-actions link the independent benzoates alternately, forming a chain structure. In the crystals of (B) and (C), mol-ecules are linked through O-H⋯O and C-H⋯π inter-actions, and C-H⋯O hydrogen bonds, respectively, into similar chains. Further, weak inter-molecular C-H⋯O inter-actions connect the chains into a three-dimensional network in (A) and a sheet in (B), whereas no other interactions are observed for (C).

Preparation and characterization of plasticized palm-based polyurethane solid polymer electrolyte

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

Daud, Farah Nadia; Ahmad, Azizan; Badri, Khairiah Haji

2013-11-27

Palm-based polyurethane solid polymer electrolyte was prepared via prepolymerization method between palm kernel oil based polyols (PKO-p) and 2,4’-diphenylmethane diisocyanate (2,4’-MDI) in acetone at room temperature with the vary amount of lithium trifuoromethanesulfonate (LiCF{sub 3}SO{sub 3}) salt and polyethylene glycol (PEG). The film was analyzed using attenuated total reflection infrared (ATR-IR) spectroscopy, electrochemical impedance spectroscopy (EIS) and X-ray diffractometry (XRD). EIS result indicated ionic conductivity obtained with 30 wt% LiCF3SO3 increased to 6.55 × 10{sup −6} S cm{sup −1} when 10 wt.% of plasticizer was added into the system. FTIR analysis showed the interaction between lithium ions and amine (-N-H)more » at 3600–3100 cm{sup −1}, carbonyl (-C=O) at 1750–1650 cm{sup −1} and ether (-C-O-C-) at 1150–1000 cm{sup −1} of the polyurethane forming polymer-salt complexes. The XRD result confirmed that LiCF{sub 3}SO{sub 3} salt completely dissociated within the polyurethane film with the absence of crystalline peaks of LiCF{sub 3}SO{sub 3}.« less

Synthesis and structure of U(VI), Np(VI), and Pu(VI) propionates

NASA Astrophysics Data System (ADS)

Serezhkin, V. N.; Grigor'ev, M. S.; Abdul'myanov, A. R.; Fedoseev, A. M.; Serezhkina, L. B.

2015-11-01

Crystals of [ AnO2(C2H5COO)2(H2O)2], where An = U (I), Np (II), or Pu (III), have been synthesized and studied by X-ray diffraction at 100 K. Compounds I-III are isostructural and crystallize in the monoclinic system, sp. gr. C2/ c, Z = 4, with the following unit-cell parameters: a = 7.4677(2), 7.4740(1), 7.512(2) Å, b = 14.2384(4), 14.1681(3), 14.182(4) Å, c = 10.5977(3), 10.5875(2), 10.607(3) Å, β = 92.384(1)°, 92.476(1)°, 92.668(17)°. Crystals I-III are composed of the mononuclear complexes [ AnO2(C2H5COO)2(H2O)2] as the main structural units belonging to the crystal-chemical group AB 01 2 M 1 2 ( A= AnO2+ 2, B 01 = C2H5COO-, M 1 = H2O). The crystal-chemical analysis of the structures of compounds of the composition UO2 L 2 · nH2O, where L is the carboxylate ion, is performed.

Crystal structure of 4-meth-oxy-N-(piperidine-1-carbono-thio-yl)benzamide.

PubMed

Suhud, Khairi; Hasbullah, Siti Aishah; Ahmad, Musa; Heng, Lee Yook; Kassim, Mohammad B

2017-10-01

In the title compound, C 14 H 18 N 2 O 2 S, the piperidine ring has a chair conformation. Its mean plane is twisted with respect to the 4-meth-oxy-benzoyl ring, with a dihedral angle of 63.0 (3)°. The central N-C(=S)-N(H)-C(=O) bridge is twisted with an N-C-N-C torsion angle of 74.8 (6)°. In the crystal, mol-ecules are linked by N-H⋯O and C-H⋯O hydrogen bonds, forming chains along the c -axis direction. Adjacent chains are linked by C-H⋯π inter-actions, forming layers parallel to the ac plane. The layers are linked by offset π-π inter-actions [inter-centroid distance = 3.927 (3) Å], forming a supra-molecular three-dimensional structure.

Norfloxacin sesquihydrate

PubMed Central

Ravindra, Nittala V.; Panpalia, Gopal M.; Jagarlapudi, A. R. P. Sarma

2009-01-01

In the crystal structure of the title compound [systematic name: 1-ethyl-6-fluoro-4-oxo-7-(piperazin-4-ium-1-yl)-1,4-dihydro­quinoline-3-carboxyl­ate sesquihydrate], C16H18FN3O3·1.42H2O, N—H⋯O and O—H⋯O hydrogen bonds assemble the mol­ecules in a two-dimensional layered corrugated sheet structure parallel to the b axis. The water mol­ecules are disordered [occupancies 0.741 (11) and 0.259 (11)]. PMID:21581912

Radical-molecule reaction C3H+H2O: a mechanistic study.

PubMed

Dong, Hao; Ding, Yi-Hong; Sun, Chia-Chung

2005-02-08

Despite the importance of the C(3)H radical in both combustion and interstellar space, the reactions of C(3)H toward stable molecules have never been studied. In this paper, we report our detailed mechanistic study on the radical-molecule reaction C(3)H+H(2)O at the Becke's three parameter Lee-Yang-Parr-B3LYP6-311G(d,p) and coupled cluster with single, double, and triple excitations-CCSD(T)6-311G(2d,p) (single-point) levels. It is shown that the C(3)H+H(2)O reaction initially favors formation of the carbene-insertion intermediates HCCCHOH (1a,1b) rather than the direct H- or OH-abstraction process. Subsequently, the isomers (1a,1b) can undergo a direct H- extrusion to form the well-known product propynal HCCCHO (P(5)). Highly competitively, (1a,1b) can take the successive 1,4- and 1,2-H-shift interconversion to isomer H(2)CCCHO(2a,2b) and then to isomer H(2)CCHCO(3a,3b), which can finally take a direct C-C bond cleavage to give product C(2)H(3) and CO (P(1)). The other products are kinetically much less feasible. With the overall entrance barrier 10.6 kcal/mol, the title reaction can be important in postburning processes. Particularly, our calculations suggest that the title reaction may play a role in the formation of the intriguing interstellar molecule, propynal HCCCHO. The calculated results will also be useful for the analogous C(3)H reactions such as with ammonia and alkanes.

Quick and simple sample treatment for multiresidue analysis of bisphenols, bisphenol diglycidyl ethers and their derivatives in canned food prior to liquid chromatography and fluorescence detection.

PubMed

Alabi, A; Caballero-Casero, N; Rubio, S

2014-04-04

We report herein a multiresidue method for canned food determination of 12 bisphenols [bisphenol A (BPA), bisphenol B (BPB), bisphenol F (BPF), bisphenol E (BPE)], bisphenol diglycidyl ethers [bisphenol F diglycidyl ether (BFDGE), bisphenol A diglycidyl ether (BADGE)] and their derivatives [BADGE·2H2O, BADGE·H2O, BADGE·HCl·H2O, BADGE·HCl, BADGE·2HCl and BFDGE·2HCl]. The method was based on the microextraction of the target contaminants in 200mg food sample with 600 μL of a supramolecular solvent made up of inverse aggregates of tetradecanol, followed by analysis of the extract by liquid chromatography/fluorescence detection using external calibration. Chromatographic separation of all target compounds, including the ortho-ortho, ortho-para and para-para isomers of BFDGE and BFDGE·2HCl, was achieved with baseline separation (Resolution ≥ 1.52). No concentration of the extracts was required, the microextraction took about 30 min and several samples could be simultaneous treated. Method validation was carried out according to the recommendations of the European Commission Decision 2002/657/EC. Quantitation limits for the different analytes ranged between 0.9 and 3.5 μg kg(-1). Repeatability and reproducibility, expressed as relative standard deviation, were in the ranges 1.8-6.8% and 4.4-8.1%. The method was applied to the analysis of the target compounds in different food categories including vegetables, legumes, fruits, fish and seafood, meat product and grain. Recoveries in samples were within the range 80-110%. Only BPF and BPE were undetected in the canned food analyzed. The concentration found for the rest of bisphenols, diglycidyl ethers and derivatives was in the range 7.1-959 μg kg(-1). The study of the isomeric distribution of BFDGE and BFDGE·2HCl in food showed that they are preferentially present as one of the isomeric forms, that highlighting for further studies. The analytical and operational characteristics of this multiresidue method make it suitable for monitoring programs intended for the assessment of human exposure to bisphenols, diglycidyl ethers and derivatives from diet. Copyright © 2014 Elsevier B.V. All rights reserved.

Respiratory strategy is a major determinant of [3H]water and [14C]chlorpyrifos uptake in aquatic insects

USGS Publications Warehouse

Buchwalter, D.B.; Jenkins, J.J.; Curtis, L.R.

2002-01-01

Despite the extensive use of aquatic insects to evaluate freshwater ecosystem health, little is known about the underlying factors that result in sensitivity differences between taxa. Organismal characteristics (respiratory strategy and body size) were used to explore the rates of [3H]H2O and [14)C]chlorpyrifos accumulation in aquatic insects. Ten aquatic insect taxa, including ephemeropteran, trichopteran, dipteran, hemipteran, and coleopteran species, were exposed to [14C]chlorpyrifos (240 ng??L-1) and [3H]H2O for up to 12 h. Because exchange epithelial surfaces on the)integument are permeable to water, [3H]H2O was used as a quantitative surrogate for exposed cellular surface area.) [14C]Chlorpyrifos uptake rates were highly correlated with water permeability in all 10 taxa tested and largely covaried with body size and respiratory strategy. Rates were highest among smaller organisms on a per-weight basis and in taxa with relatively large external cellular surfaces such as gills. Air-breathing taxa were significantly less permeable to both [3)HH20 and [14C)C]chlorpyrifos. A method for labeling exposed epithelial surfaces with a fluorescent dye was developed. This technique allowed discrimination between exchange epithelium and barrier tissue on the integument. Fluorescent dye distributions on the body surface provided a rapid method for estimating exposed epithelium consistent with [3H]H2O and [14)C]chlorpyrifos accumulation.

The chemistry of subcritical water reactions of a hardwood derived lignin and lignin model compounds with nitrogen, hydrogen, carbon monoxide and carbon dioxide

NASA Astrophysics Data System (ADS)

Hill Bembenic, Meredith A.

Biofuels, like cellulosic ethanol, may only be cost effective if the lignin byproduct is upgraded to value-added products. However, lignin's inherent aromatic structure and interunit crosslinkages hinder effective conversion. High temperature H2O is considered for lignin conversion, because H2O exhibits unusual properties at higher temperatures (particularly at its supercritical point of 374°C and 3205 psi) including a decreased ion product and a decreased static dielectric constant (similar to those of polar organic solvents at room temperature) such that there is a high solubility for organic compounds, like lignin. Much of the research concerning lignin and supercritical H2O has focused on further decomposition to gases (e.g., H2, CH4, and CO2) where nearly no char formation is expected in the presence of a catalyst. However, the conditions required for supercritical H2O are difficult to maintain, catalysts can be expensive, and gases are not favorable to the current liquid fuel infrastructure. Reactions using Organosolv lignin, subcritical H2O (365°C) and various industrial gases (N2, H2, CO, and CO2 at an initial pressure of 500 psi) for 30 min. were examined to determine both lignin's potential to generate value-added products (e.g., monomer compounds and methanol) and the role (if any) of the H2O and the gases during the reactions. The behavior of H2O at reaction temperature and pressure is expected to be similar to the behavior of supercritical H 2O without the need to maintain supercritical conditions. Different characterization techniques were used for the products collected including primarily GC/FID-TCD of the evolved gases, GC/MS analysis of the organic liquids, solid phase microextraction analysis of the water, and solid state 13C-NMR analysis of the residues. The reactor pressure at temperature was shown to influence the reactivity of the H2O and lignin, and the highest conversions (≈54--62%) were obtained when adding a gas. However, the collected solids from the CO reactions appeared to be the most reacted (i.e., the most changed from the unreacted lignin) according to solid state 13C-NMR analysis, and the widest variety of products (methoxy-substituted phenolic compounds) were obtained when using CO according to GC/MS analysis. Therefore, reactions with CO were completed that varied the initial reaction pressure (300, 500 and 800 psi) in order to elucidate the effects of CO pressure. Similar conversion (≈54--58%) and DCM-soluble liquid product yields (≈53--62%) were obtained for the different pressure reactions, but the reactions with an initial pressure of 500 psi had the greatest change in aromaticity from the unreacted lignin. Additional reactions between Organosolv lignin and H2O with CO (initial pressure of 500 psi) were conducted where the reaction time was varied (15, 30 and 60 min.) to determine the effect of reaction time. Longer reaction time (60 min.) appeared to inhibit conversion to low molecular weight compounds (i.e., conversion and DCM-soluble yields were lower at ≈53% and ≈28%, respectively). Solid state 13C-NMR of collected residues also showed that there are losses in carbons representative of both guaiacyl and syringyl components as reaction time increases, which may indicate that methoxy groups are being cleaved or the products are reacting with each other (i.e., repolymerization) to form high molecular weight compounds as reaction time is increased. The role of H2O and the gases during the baseline reactions and the expanded CO reactions is not intuitive based on the results, so reactions with lignin model compounds (i.e., aromatic aldehydes represented by vanillin and syringaldehyde, aromatic ketones represented by acetovanillone and acetosyringone, and aromatic ethers represented by dibenzyl ether and 2-phenethyl phenyl ether) were completed to study this. From these results, the suggested reaction pathway of Organosolv lignin reactions in subcritical H2O with and without added pressure is: 1) cleavage of ethers (via hydrolysis) to form smaller methoxy-substituted phenolic monomers with aldehyde- or ketone-substituents representative of lignin monomers; 2) cleavage of the methoxy-, aldehyde- and/or ketone-substituents to form primarily methoxy-substituted phenolic monomers; 3) rearrangement of these phenolic monomers due to the enhanced pressure at reaction temperature; 4) formation of oligomers due to interaction amongst the methoxy-substituted phenolic monomers, which is also due to the enhanced pressure at reaction temperature; and 5) repolymerization of the monomers and oligomers to form high molecular weight compounds (i.e., longer reactions times or different pressures seemed to enhance these reactions). Under these conditions, depolymerization seems to be the dominant reaction pathway versus repolymerization. Reactions with lignin and H2O at 365°C have not been previously reported nor has the reaction chemistry for lignin depolymerization at these conditions been established. The results with lignin (or lignin model compounds), subcritical H2O and CO also show that the desired product slate can be modified with different pressure and time conditions. In particular, increasing reaction time (from 15 to 60 min.) caused lignin conversion to decrease, and the products appeared to be reacting with each other. However, the longer reaction time also showed that more methanol is generated (along with more solids).

Projections of Demand for Waterborne Transportation, Ohio River Basin, 1980, 1990, 2000, 2020, 2040. Volume 9. Group VII. Ores and Minerals.

DTIC Science & Technology

1980-12-01

U l 0 0 ) C 4140 c4 34jE 04 0)t 03.- In lo No ID 0ID 6)ID M). U 0 ( in cc m m m c m mm m a a) la.0u) 0r- 02d)20 C ’N C ~ 3 C -27- c -o 0 It14’ 0 14 tn...N 1.D/ c4 0)00E w.~ 0 V-- -"- -- V04 M1)4VdW -4I -..- 1. 0001M.-40 00 4D4J.’ ::l c:; Q o u00 0 0.0 a 0~~ ~ m𔃺 w , 0-0m.-Q)uH 1.4 0 : . 0 4140 .0 ZZl...Statistical Report. 1969-78 eds. Washington, D.C.: AISI , 1970-79. American Metal Market. Metal Statistics. 1970 -d. New York: Fairchild, 1976. "Facts and

Effect analysis of quantum chemical descriptors and substituent characteristics on Henry's law constants of polybrominated diphenyl ethers at different temperatures.

PubMed

Long, Jiang; Youli, Qiu; Yu, Li

2017-11-01

Twelve substituent descriptors, 17 quantum chemical descriptors and 1/T were selected to establish a quantitative structure-property relationship (QSPR) model of Henry's law constants for 7 polybrominated diphenyl ethers (PBDEs) at five different temperatures. Then, the lgH of 202 congeners at different temperatures were predicted. The variation rule and regulating mechanism of lgH was studied from the perspectives of both quantum chemical descriptors and substituent characteristics. The R 2 for modeling and testing sets of the final QSPR model are 0.977 and 0.979, respectively, thus indicating good fitness and predictive ability for Henry' law constants of PBDEs at different temperatures. The favorable hydrogen binding sites are the 5,5',6,6'-positions for high substituent congeners and the O atom of the ether bond for low substituent congeners, which affects the interaction between PBDEs and water molecules. lgH is negatively and linearly correlated with 1/T, and the variation trends of lgH with temperature are primarily regulated by individual substituent characteristics, wherein: the more substituents involved, the smaller the lgH. The significant sequence for the main effect of substituent positions is para>meta>ortho, where the ortho-positions are mainly involved in second-order interaction effect (64.01%). Having two substituents in the same ring also provides a significant effect, with 81.36% of second-order interaction effects, particularly where there is an adjacent distribution (55.02%). Copyright © 2017 Elsevier Inc. All rights reserved.

Second International Conference on Snow Engineering.

DTIC Science & Technology

1992-12-01

the Wiinter 10 aa 0. cS," 0’ 00 < 0~ - ap aa aa a a a a a - - -(p,,l O IID A (11 OuI JDI (3/ill) JJDMIM ol 0 8 N~ ~ T -\\----- w to co ad ba a C. ’ C6...V {l H 2.2 󈧐-2. *, 10 - C @ 2.0 + ® 8 - A • _ -1.8 06 C, 1.6 x 1.4 "" - - . 1.2 " 0 t 0 x 1.2 - Type! Type I Typelll Normal Lognormal 1.0 : Annual...n ua cO000 e rP s dxtrep e Snow Depths 0 - (an) 1500 200 300 400 Fig. 8 . Relationship between W... and H,,,, Wim i (kgf/ni) gN r MRI values of A : 10

Vibrational, NMR spectrum and orbital analysis of 3,3',5,5'-tetrabromobisphenol A: a combined experimental and computational study.

PubMed

Qiu, Shanshan; Wei, Jin; Pan, Feng; Liu, Jingping; Zhang, Aiqian

2013-03-15

In the present work, the experimental and theoretical studies on the structure, vibrations, NMR and HOMO-LUMO analysis of 3,3',5,5'-tetrabromobisphenol A (TBBPA) are presented. The FT-IR (400-4000 cm(-1)) and FT-Raman (100-4000 cm(-1)) spectra of TBBPA were recorded. The molecular geometry, vibrational frequencies were calculated by using density functional theory (DFT) method with the 6-31G(d) basis set. The optimized geometric properties, scaled vibrational wavenumbers, IR intensities, Raman activities show good agreement with the experimental data. The assigned vibrational modes of the IR and Raman spectra were compared with the corresponding properties of the polybrominated diphenyl ethers (PBDEs). Comparative analysis indicated that the red shift of C-Br vibration could probably be ascribed to the further electronic density equalization due to the p-π conjugation between O atom and the benzene. The natural bonding orbital (NBO) analysis demonstrated that the intermolecular hyperconjugative interactions are mainly formed by the orbital overlap between σ (O-H), σ(*) (C-C), π (C-C), π(*) (C-C) bond orbitals. Compared to the higher E((2)) value (33.65-34.82 kcal/mol) originated from LP(2)O to π(*) (C-C), the one (E((2)): 8.23-9.73 kcal/mol) from LP(3)Br and π(*) (C-C) contributes to the preferential tendency of C-Br breakage to the C-O breakage in the transformation. The calculated NMR results obtained on the 6-31G(d) level proves good agreement with the experimental data (r(2)=0.999). Analysis of isosurface of the related orbital shows that all the main excitation exhibit π-π(*) character localized on the benzene rings. Copyright © 2012 Elsevier B.V. All rights reserved.

Proton Conduction in Tröger's Base Linked Poly(crown ether)s.

PubMed

Patel, Hasmukh A; Selberg, John; Salah, Dhafer; Chen, Haoyuan; Liao, Yijun; Nalluri, Siva Krishna Mohan; Farha, Omar K; Snurr, Randall Q; Rolandi, Marco; Stoddart, J Fraser

2018-06-05

Exactly 50 years ago, the ground-breaking discovery of dibenzo[18]crown-6 (DB18C6) by Charles Pedersen, led to the use of DB18C6 as a receptor in supramolecular chemistry and a host in host‒guest chemistry. We have demonstrated proton conductivity in Tröger's base-linked polymers through hydrogen-bonded networks formed from adsorbed water molecules on the oxygen atoms of DB18C6 under humid conditions. Tröger's base-linked polymers - poly(TBL‒DB18C6)-t and poly(TBL‒DB18C6)-c - synthesized by the in situ alkylation and cyclization of either trans- or cis-di(aminobenzo) [18]crown-6 at room temperature have been isolated as high molecular weight polymers. The macromolecular structures of the isomeric poly(TBL‒DB18C6)s have been established by spectroscopic techniques and size-exclusion chromatography. The excellent solubility of these polymers in chloroform allows the formation of free-standing membranes which are thermally stable and also show stability under aqueous conditions. The hydrophilic nature of the DB18C6 building blocks in the polymer facilitates retention of the water as confirmed by water-vapor adsorption isotherms which show a 23 wt% water uptake. The adsorbed water is retained even after reducing the relative humidity to 25 %. The proton conductivity of poly(TBL‒DB18C6)-t which is found to be 1.4 x 10‒4 mS cm‒1 in a humid environment, arises from the hydrogen bonding and the associated proton hopping mechanism, as supported by a modeling study. In addition to proton conductivity, the Tröger's base-linked polymers reported here promise a wide range of applications where the sub-nanometer-sized cavities of the crown ethers and the robust film-forming ability are the governing factors in dictating their properties.

Amine templating effect absent in uranyl sulfates synthesized with 1,4-n-butyldiamine

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

Jouffret, Laurent J., E-mail: ljouffret@nd.edu; Wylie, Ernest M.; Burns, Peter C.

2013-01-15

Two new uranyl sulfates, (C{sub 4}H{sub 14}N{sub 2})[(UO{sub 2}){sub 2}(SO{sub 4}){sub 3}(H{sub 2}O)]{center_dot}2H{sub 2}O (NDUS2) and (C{sub 4}H{sub 14}N{sub 2})[(UO{sub 2})(SO{sub 4}){sub 2}(H{sub 2}O)]{center_dot}2H{sub 2}O (NDUS3), were synthesized and their crystal structures determined. NDUS2 was obtained in highly acidic media heat-treated at 373 K and subsequently maintained at 278 K until crystals formed after two months. NDUS3 results from the degradation of NDUS2 over the course of a few days. NDUS2 and NDUS3 crystallize in the monoclinic space group P2{sub 1}/n, a=10.9075(4) A, b=10.4513(4) A, c=17.7881(7) A, {beta}=97.908(2) Degree-Sign , V=2008.52(13) A{sup 3}, Z=4, at 140 K and a=8.8570(4) A,more » b=7.3299(3) A, c=20.4260(9) A, {beta}=95.140(2) Degree-Sign , V=1320.74(10) A{sup 3}, Z=4, at 140 K, respectively. The compounds contain interlayer 1,4-n-butyldiammonium cations that charge-balance the anionic structural units. - Graphical abstract: Amine templating effect absent in uranyl sulfates synthesized with 1,4-diaminobutane, as shown by the synthesis of two new uranyl sulfates, (C{sub 4}H{sub 14}N{sub 2})[(UO{sub 2}){sub 2}(SO{sub 4}){sub 3}(H{sub 2}O)]{center_dot}2H{sub 2}O (NDUS2) and (C{sub 4}H{sub 14}N{sub 2})[(UO{sub 2})(SO{sub 4}){sub 2}(H{sub 2}O)]{center_dot}2H{sub 2}O (NDUS3). Highlights: Black-Right-Pointing-Pointer Two layered uranyl sulfates were synthesized. Black-Right-Pointing-Pointer Amine molecules are located in the interlayers of the compounds. Black-Right-Pointing-Pointer No templating effect of the amine was observed. Black-Right-Pointing-Pointer Amine molecules are only charge balancing cations in the structures.« less

RhII -Catalyzed β-C(sp2 )-H Alkylation of Enol Ethers, Enamides and Enecarbamates with α-Diazo Dicarbonyl Compounds.

PubMed

McLarney, Brett D; Cavitt, Marchello A; Donnell, Theodore M; Musaev, Djamaladdin G; France, Stefan

2017-01-23

A Rh II -catalyzed method for intermolecular alkylation of the β-C(sp 2 )-H bond of enol ethers, enamides, and enecarbamates with α-diazo-1,3-dicarbonyl compounds is reported. The products are formed in up to 99 % yield and can be readily derivatized under a variety of conditions. By utilizing a combination of experimental and computational studies, the presumptive addition-elimination reaction mechanism was investigated and found to proceed under thermodynamic control at higher temperature. The acquired fundamental knowledge was translated into a strategic reaction design and yielded the first example of the β-C-H functionalizations of acyclic enol ethers using α-diazo-1,3-dicarbonyl compounds. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Adsorption and catalytic properties of sulfated aluminum oxide modified with cobalt ions

NASA Astrophysics Data System (ADS)

Lanin, S. N.; Bannykh, A. A.; Vlasenko, E. V.; Krotova, I. N.; Obrezkov, O. N.; Shilina, M. I.

2017-01-01

The adsorption properties of sulfated aluminum oxide (9% SO 4 2- /γ-Al2O3) and a cobalt-containing composite (0.5%Co/SO 4 2- /γ-Al2O3) based on it are studied via dynamic sorption. The adsorption isotherms of such test adsorbates as n-hydrocarbons (C6-C8), benzene, ethylbenzene, chloroform, and diethyl ether are measured, and their isosteric heats of adsorption are calculated. It is shown that the surface sulfation of aluminum oxide substantially improves its electron-accepting properties, and so the catalytic activity of SO 4 2- /γ-Al2O3 in the liquid-phase alkylation of benzene with octene-1 at temperatures of 25-120°C is one order of magnitude higher than for the initial aluminum oxide. It is established that additional modification of sulfated aluminum oxide with cobalt ions increases the activity of this catalyst by 2-4 times. It is shown that adsorption sites capable of strong specific adsorption with both donating (aromatics, diethyl ether chemosorption) and accepting molecules (chloroform) form on the surface of sulfated γ-Al2O3 promoted by cobalt salt.

Quantum-Mechanical Studies on Chemical Reactivity and Ballistic Chemistry. VII. Semiempirical Molecular Orbital Calculations and Experimental Studies on Relative Chemical Reactivities of Isomeric Tetrazole Derivatives, and their Relationship to the Explosive Properties of some Tetrazole Derivatives

DTIC Science & Technology

1981-10-01

factor of about 20) than the methyl protons of the isomeric 2-phenyl compound-^6. Furthermore, when N-(4-dimethylaminophenyl) nitrones are reacted...34Tetrazoles from N-(4-Dimethylaminophenyl) nitrones and Hydrogen Azide", J. Heteroayol. Chem., 14, 757 (1977). 17 Further examples of...r—» , M < =< e 40 X rH u 03 ■l-J ■P u 0 6 H o u u 1— cd +J 1= c S B ■H u a> ft X U-l D W HJ -J H) o 0 Kl O < ■H a TS

Molten Salt Assisted Self-Assembly: Synthesis of Mesoporous LiCoO2 and LiMn2 O4 Thin Films and Investigation of Electrocatalytic Water Oxidation Performance of Lithium Cobaltate.

PubMed

Saat, Gülbahar; Balci, Fadime Mert; Alsaç, Elif Pınar; Karadas, Ferdi; Dag, Ömer

2018-01-01

Mesoporous thin films of transition metal lithiates (TML) belong to an important group of materials for the advancement of electrochemical systems. This study demonstrates a simple one pot method to synthesize the first examples of mesoporous LiCoO 2 and LiMn 2 O 4 thin films. Molten salt assisted self-assembly can be used to establish an easy route to produce mesoporous TML thin films. The salts (LiNO 3 and [Co(H 2 O) 6 ](NO 3 ) 2 or [Mn(H 2 O) 4 ](NO 3 ) 2 ) and two surfactants (10-lauryl ether and cethyltrimethylammonium bromide (CTAB) or cethyltrimethylammonium nitrate (CTAN)) form stable liquid crystalline mesophases. The charged surfactant is needed for the assembly of the necessary amount of salt in the hydrophilic domains of the mesophase, which produces stable metal lithiate pore-walls upon calcination. The films have a large pore size with a high surface area that can be increased up to 82 m 2 g -1 . The method described can be adopted to synthesize other metal oxides and metal lithiates. The mesoporous thin films of LiCoO 2 show promising performance as water oxidation catalysts under pH 7 and 14 conditions. The electrodes, prepared using CTAN as the cosurfactant, display the lowest overpotentials in the literature among other LiCoO 2 systems, as low as 376 mV at 10 mA cm -2 and 282 mV at 1 mA cm -2 . © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Robiginitalea sediminis sp. nov., isolated from a sea cucumber culture pond.

PubMed

Zhang, Jing; Han, Ji-Ru; Chen, Guan-Jun; Du, Zong-Jun

2018-06-01

A Gram-stain negative, aerobic, non-motile, orange and rod/coccoid-shaped bacterium, designated O458 T , was isolated from sediment collected from a sea cucumber culture pond located in Rongcheng, Shandong province, China (122°14'E, 36°54'N). Comparative analysis of 16S rRNA gene sequences revealed that strain O458 T is a member of the genus Robiginitalea and is closely related to Robiginitalea biformata (95.7% sequence similarity) and Robiginitalea myxolifaciens (94.9%). Its DNA G+C content was 55.2 mol%. The strain grew at temperatures between 15 and 45 °C (optimum 33 °C), from pH 6.5 to 8.5 (optimum pH 7.0-7.5) and between 1.0 and 6.0% (w/v) NaCl (optimum 2.0%). Strain O458 T was found to contain menaquinon-6 (MK-6) as the only respiratory quinone, iso-C 15:0 , iso-C 17:0 3-OH and Summed feature 1 (iso-C 15:1 H and/or iso-C 13:0 3-OH) as the major fatty acids. The major polar lipids were phosphatidylethanolamine (PE) and four unidentified lipids (L1, L2, L3 and L4). On the basis of the results of the phylogenetic and phenotypic analyses it is suggested that strain O458 T represents a novel species of the genus Robiginitalea, for which the name Robiginitalea sediminis sp. nov. is proposed. The type strain is O458 T (=KCTC 52898 T =MCCC 1H00190 T ).

Influence of plant root exudates, germ tube orientation and passive conidia transport on biological control of fusarium wilt by strains of nonpathogenic Fusarium oxysporum.

PubMed

Mandeel, Qaher A

2006-03-01

In earlier studies, biological control of Fusarium wilt of cucumber induced by Fusarium oxysporum f. sp. cucumerinum was demonstrated using nonpathogenic strains C5 and C14 of Fusarium oxysporum. Strain C14 induced resistance and competed for infection sites whether roots were wounded or intact, whereas strain C5 required wounds to achieve biocontrol. In the current work, additional attributes involved in enhanced resistance by nonpathogenic biocontrol agents strains to Fusarium wilt of cucumber and pea were further investigated. In pre-penetration assays, pathogenic formae specials exhibited a significantly higher percentage of spore germination in 4-day-old root exudates of cucumber and pea than nonpathogens. Also, strain C5 exhibited the lowest significant reduction in spore germination in contrast to strain C14 or control. One-day-old cucumber roots injected with strain C14 resulted in significant reduction in germ tube orientation towards the root surface, 48-96 h after inoculation with F. o. cucumerinum spores, whereas strain C5 induced significantly lower spore orientation of the pathogen and only at 72 and 96 h after inoculation. In post-penetration tests, passive transport of microconidia of pathogenic and nonpathogens in stems from base to apex were examined when severed plant roots were immersed in spore suspension. In repeated trials, strain C5, F. o. cucumerinum and F. o. pisi were consistently isolated from stem tissues of both cucumber and pea at increasing heights over a 17 days incubation period. Strain C14 however, was recovered at a maximum translocation distance of 4.6 cm at day 6 and later height of isolation significantly declined thereafter to 1.2 cm at day 17. In pea stem, the decline was even less. Significant induction of resistance to challenge inoculation by the pathogen in cucumber occurred 72 and 96 h after pre-inoculation with biocontrol agents. Nonetheless, strain C14 induced protection as early as 48 h and the maximum resistance was reached at 96 h. The presented data confirm the previous findings that attributes important for nonpathogenic fusaria to induce resistant are: rapid spore germination and orientation in response to root exudate; active root penetration and passive conidia transport in stem to initiate defence reaction without pathogenicity and enough lag period between induction and challenge inoculation. Strain C14 possesses all these qualifications and hence its ability to enhance host resistance is superior than strain C5.

Cross-dehydrogenative coupling and oxidative-amination reactions of ethers and alcohols with aromatics and heteroaromatics

PubMed Central

Vuram, Prasanna K.

2017-01-01

Cross-dehydrogenative coupling (CDC) is a process in which, typically, a C–C bond is formed at the expense of two C–H bonds, either catalyzed by metals or other organic compounds, or via uncatalyzed processes. In this perspective, we present various modes of C–H bond-activation at sp3 centers adjacent to ether oxygen atoms, followed by C–C bond formation with aromatic systems as well as with heteroaromatic systems. C–N bond-formation with NH-containing heteroaromatics, leading to hemiaminal ethers, is also an event that can occur analogously to C–C bond formation, but at the expense of C–H and N–H bonds. A large variety of hemiaminal ether-forming reactions have recently appeared in the literature and this perspective also includes this complementary chemistry. In addition, the participation of C–H bonds in alcohols in such processes is also described. Facile access to a wide range of compounds can be attained through these processes, rendering such reactions useful for synthetic applications via Csp3 bond activations. PMID:28970941

National Program for Inspection of Non-Federal Dams. Cleveland Brook Reservoir (Dam MA 00225), Housatonic River Basin, Hinsdale, Massachusetts. Phase I Inspection Report.

DTIC Science & Technology

1979-06-01

wf ’U ~ ~ ~ a~ 77-1 . M. , .16. O~lAIL OP OF OMAft TO SLW-F PIPE~LCCABE O i O-FFi I - - - SCALL CA ri.w -0p -" ~4bb .Aw 15CSCAL l1.4d .4* 4o %R*a...11’ sia !e, Massac.husettsNX FFE 6H,..NO RATEF, c. 3VA’l 7a tAS NO SAMPLER CORE BAR. ms - T FT AFrH... HS TagL SS NC A TE 1___ 9/1G,_____7c__ -. 1

Coordinated Research Program in Pulsed Power Physics.

DTIC Science & Technology

1981-12-01

Ref. C11, this problem may be elimi- nated by factoring the tridiagonal , 2nd order, finite difference equation, Eq. (1), into two ist order finite ...13)Ti,o where 1h 2 /2 h2 = 2 - g + / -h g (1- - g) (14) 1+ h This solution to the finite difference equations consists of expo- nentially growing...December 1, 1981fl j,/,,- //,CJ’ .* ., .) - 13. NUMBEROF PAGES - A.)6 2 /’ij250 14. MONITORING AGENCY NAME & ADDRESS(iI different from Controlling

Diffusion of dioxygen in 1-alkenes and biphenyl in perfluoro- n-alkanes

NASA Astrophysics Data System (ADS)

Kowert, Bruce A.; Sobush, Kurtis T.; Dang, Nhan C.; Seele, Louis G., III; Fuqua, Chantel F.; Mapes, Courtney L.

2002-02-01

The translational diffusion constant, D, has been measured for O 2 in the even 1-alkenes 1-C 6H 12 to 1-C 16H 32 and biphenyl in n-C 6F 14 and n-C 9F 20. Deviations from the Stokes-Einstein relation were found; the use of D/ T= A/ ηp gave p=0.560±0.017 for O 2 in the 1-alkenes, the same (within experimental error) as found previously for O 2 in the n-alkanes. The charge transfer (CT) transition used to detect O 2 in the 1-alkenes is at 220 nm. The D values for biphenyl in the perfluoro- n-alkanes (PFAs) are consistent with those in the n-alkanes, where p=0.718±0.004. These results suggest that O 2 has similar solute-solvent interactions in both the 1-alkenes and n-alkanes as does biphenyl in the n-alkanes and PFAs.

Nonlinear, Incremental Structural Analysis of Olmsted Locks and Dams. Volume 2: Appendixes A through I

DTIC Science & Technology

1992-12-01

steel Hr 14x117: A = 34.4 in E - 29,000,000 psi From plans provided: L - 708 in k - 1.25(34.4...El 5 U.M. il IIl I E1~ E16 40I " , _j* tool cn toA LI LL E17 Iiin Ii i cc, LL E18 11- - - U.a. U.T. ’-3 1-4 LIJ ri m q O E19 61 Uj p41’ I WI m- 14 LL...4 ’o 4 4 Ca L ~Ln 04 :L H13 00 cc I.- 1 cn LU c’J 0I z CLoZ 1A1 J: , f * 1:T T--/ CC LIL 4-4J H5l Cr) A A 1 .1, , +,-C +~ + CL H6 L1 Ul LMz WA0

5-Methylpyrazine-2-carboxamide

DOE PAGES

Rillema, D. Paul; Senaratne, Nilmini K.; Moore, Curtis; ...

2017-07-28

The title compound, C 6H 7N 3O, is nearly planar, with a dihedral angle of 2.14 (11)° between the pyrazine ring and the mean plane of the carboxamide group [C—C(=O)—N]. In the crystal, molecules are linked via pairs of N—H...O hydrogen bonds forming inversion dimers with an R 2 2 (8) ring motif. These dimers are further linked by a pair of N—H...N hydrogen bonds, enclosing an R 2 2 (10) ring motif, and C—H...O hydrogen bonds, forming ribbons lying parallel to the ab plane. The ribbons are linked by offset π–π interactions [intercentroid distance = 3.759(1)Å], forming two setsmore » of mutually perpendicular slabs parallel to planes (110) and (1-10).« less

Regioselective oxyalkylation of vinylarenes catalyzed by diatomite-supported manganese oxide nanoparticles.

PubMed

Sun, Huayin; Zhang, Yonghui; Guo, Fengfeng; Zha, Zhenggen; Wang, Zhiyong

2012-04-06

A regioselective oxyalkylation reaction of vinylarenes with cyclic ethers was developed under the catalysis of a new heterogeneous catalyst, the diatomite-supported Mn(3)O(4) nanoparticles (SMONP-1). The use of this heterogeneous catalyst provided a novel approach for the synthesis of α-carbonyled β-alkylated aryl derivatives via a sp(3) C-H bond functionalization under mild aerobic conditions.

Low temperature (550-700 K) oxidation pathways of cyclic ketones: Dominance of HO 2-elimination channels yielding conjugated cyclic coproducts

DOE PAGES

Scheer, Adam M.; Welz, Oliver; Vasu, Subith S.; ...

2015-04-13

The low-temperature oxidation of three cyclic ketones, cyclopentanone (CPO; C 5H 8O), cyclohexanone (CHO; C 6H 10 O), and 2-methyl-cyclopentanone (2-Me-CPO; CH 3–C 5H7 O), is studied between 550 and 700 K and at 4 or 8 Torr total pressure. Initial fuel radicals R are formedvia fast H-abstraction from the ketones by laser-photolytically generated chlorine atoms. Intermediates and products from the subsequent reactions of these radicals in the presence of excess O 2 are probed with time and isomeric resolution using multiplexed photoionization mass spectrometry with tunable synchrotron ionizing radiation. For CPO and CHO the dominant product channel in themore » R + O 2 reactions is chain-terminating HO 2-elimination yielding the conjugated cyclic coproducts 2-cyclopentenone and 2-cyclohexenone, respectively. Results on oxidation of 2-Me-CPO also show a dominant contribution from HO 2-elimination. Moreover, the photoionization spectrum of the co-product suggests formation of 2-methyl-2-cyclopentenone and/or 2-cyclohexenone, resulting from a rapid Dowd–Beckwith rearrangement, preceding addition to O 2, of the initial (2-oxocyclopentyl)methyl radical to 3-oxocyclohexyl. Cyclic ethers, markers for hydroperoxyalkyl radicals (QOOH), key intermediates in chain-propagating and chain-branching low-temperature combustion pathways, are only minor products. The interpretation of the experimental results is supported by stationary point calculations on the potential energy surfaces of the associated R + O 2 reactions at the CBS-QB3 level. Furthermore, the calculations indicate that HO 2-elimination channels are energetically favored and product formation via QOOH is disfavored. Lastly, the prominence of chain-terminating pathways linked with HO 2 formation in low-temperature oxidation of cyclic ketones suggests little low-temperature reactivity of these species as fuels in internal combustion engines.« less

Low temperature (550-700 K) oxidation pathways of cyclic ketones: Dominance of HO 2-elimination channels yielding conjugated cyclic coproducts

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

Scheer, Adam M.; Welz, Oliver; Vasu, Subith S.

The low-temperature oxidation of three cyclic ketones, cyclopentanone (CPO; C 5H 8O), cyclohexanone (CHO; C 6H 10 O), and 2-methyl-cyclopentanone (2-Me-CPO; CH 3–C 5H7 O), is studied between 550 and 700 K and at 4 or 8 Torr total pressure. Initial fuel radicals R are formedvia fast H-abstraction from the ketones by laser-photolytically generated chlorine atoms. Intermediates and products from the subsequent reactions of these radicals in the presence of excess O 2 are probed with time and isomeric resolution using multiplexed photoionization mass spectrometry with tunable synchrotron ionizing radiation. For CPO and CHO the dominant product channel in themore » R + O 2 reactions is chain-terminating HO 2-elimination yielding the conjugated cyclic coproducts 2-cyclopentenone and 2-cyclohexenone, respectively. Results on oxidation of 2-Me-CPO also show a dominant contribution from HO 2-elimination. Moreover, the photoionization spectrum of the co-product suggests formation of 2-methyl-2-cyclopentenone and/or 2-cyclohexenone, resulting from a rapid Dowd–Beckwith rearrangement, preceding addition to O 2, of the initial (2-oxocyclopentyl)methyl radical to 3-oxocyclohexyl. Cyclic ethers, markers for hydroperoxyalkyl radicals (QOOH), key intermediates in chain-propagating and chain-branching low-temperature combustion pathways, are only minor products. The interpretation of the experimental results is supported by stationary point calculations on the potential energy surfaces of the associated R + O 2 reactions at the CBS-QB3 level. Furthermore, the calculations indicate that HO 2-elimination channels are energetically favored and product formation via QOOH is disfavored. Lastly, the prominence of chain-terminating pathways linked with HO 2 formation in low-temperature oxidation of cyclic ketones suggests little low-temperature reactivity of these species as fuels in internal combustion engines.« less

Secondary metabolites of ponderosa lemon (Citrus pyriformis) and their antioxidant, anti-inflammatory, and cytotoxic activities.

PubMed

Hamdan, Dalia; El-Readi, Mahmoud Zaki; Tahrani, Ahmad; Herrmann, Florian; Kaufmann, Dorothea; Farrag, Nawal; El-Shazly, Assem; Wink, Michael

2011-01-01

Column chromatography of the dichloromethane fraction from an aqueous methanolic extract of fruit peel of Citrus pyriformis Hassk. (Rutaceae) resulted in the isolation of seven compounds including one coumarin (citropten), two limonoids (limonin and deacetylnomilin), and four sterols (stigmasterol, ergosterol, sitosteryl-3-beta-D-glucoside, and sitosteryl-6'-O-acyl-3-beta-D-glucoside). From the ethyl acetate fraction naringin, hesperidin, and neohesperidin were isolated. The dichloromethane extract of the defatted seeds contained three additional compounds, nomilin, ichangin, and cholesterol. The isolated compounds were identified by MS (EI, CI, and ESI), 1H, 13C, and 2D-NMR spectral data. The limonoids were determined qualitatively by LC-ESI/MS resulting in the identification of 11 limonoid aglycones. The total methanolic extract of the peel and the petroleum ether, dichloromethane, and ethyl acetate fractions were screened for their antioxidant and anti-inflammatory activities. The ethyl acetate fraction exhibited a significant scavenging activity for DPPH free radicals (IC50 = 132.3 microg/mL). The petroleum ether fraction inhibited 5-lipoxygenase with IC50 = 30.6 microg/mL indicating potential anti-inflammatory properties. Limonin has a potent cytotoxic effect against COS7 cells [IC50 = (35.0 +/- 6.1) microM] compared with acteoside as a positive control [IC50 = (144.5 +/- 10.96) microM].

Effect of solvents on the extraction of natural pigments and adsorption onto TiO2 for dye-sensitized solar cell applications

NASA Astrophysics Data System (ADS)

Al-Alwani, Mahmoud A. M.; Mohamad, Abu Bakar; Kadhum, Abd. Amir H.; Ludin, Norasikin A.

2015-03-01

Nine solvents, namely, n-hexane, ethanol, acetonitrile, chloroform, ethyl-ether, ethyl-acetate, petroleum ether, n-butyl alcohol, and methanol were used to extract natural dyes from Cordyline fruticosa, Pandannus amaryllifolius and Hylocereus polyrhizus. To improve the adsorption of dyes onto the TiO2 particles, betalain and chlorophyll dyes were mixed with methanol or ethanol and water at various ratios. The adsorption of the dyes mixed with titanium dioxide (TiO2) was also observed. The highest adsorption of the C.fruticosa dye mixed with TiO2 was achieved at ratio 3:1 of methanol: water. The highest adsorption of P.amaryllifolius dye mixed with TiO2 was observed at 2:1 of ethanol: water. H.polyrhizus dye extracted by water and mixed with TiO2 demonstrated the highest adsorption among the solvents. All extracted dye was adsorbed onto the surface of TiO2 based on Fourier Transform Infrared Spectroscopy (FTIR) analysis. The inhibition of crystallinity of TiO2 was likewise investigated by X-ray analysis. The morphological properties and composition of dyes were analyzed via SEM and EDX.

Polybrominated diphenyl ethers with potent and broad spectrum antimicrobial activity from the marine sponge Dysidea.

PubMed

Sun, Shi; Canning, Corene B; Bhargava, Kanika; Sun, Xiuxiu; Zhu, Wenjun; Zhou, Ninghui; Zhang, Yifan; Zhou, Kequan

2015-01-01

Three polybrominated diphenyl ethers, 2-(2',4'-dibromophenoxy)-3,5-dibromophenol (1) and 2-(2',4'-dibromophenoxy)-3,4,5-tribromophenol (2) were isolated from the marine sponge Dysidea granulosa; and 2-(2',4'-dibromophenoxy)-4,6-dibromophenol (3) from Dysidea spp. They exhibited potent and broad spectrum in vitro antibacterial activity, especially against methicillin resistant Staphylococcus aureus (MRSA), methicillin sensitive Staphylococcus aureus (MSSA), Escherichia coli O157:H7, and Salmonella. Minimal inhibitory concentration (MIC) was evaluated against 12 clinical and standard strains of Gram positive and negative bacteria. The observed MIC range was 0.1-4.0mg/L against all the Gram positive bacteria and 0.1-16.0mg/L against Gram negative bacteria. 2-(2',4″-Dibromophenoxy)-3,5-dibromophenol showed stronger broad spectrum antibacterial activity than other two compounds. 2-(2',4″-Dibromophenoxy)-3,5-dibromophenol and 2-(2',4'-dibromophenoxy)-4,6-dibromophenol are thermo-stable. The results suggest that 2-(2',4'-dibromophenoxy)-3,5-dibromophenol could be used as a potential lead molecule for anti-MRSA, anti-E. coli O157:H7, and anti-Salmonella for drug development. Copyright © 2015 Elsevier Ltd. All rights reserved.

Evolution of Interstellar Ices

NASA Astrophysics Data System (ADS)

Allamandola, Louis J.; Bernstein, Max P.; Sandford, Scott A.; Walker, Robert L.

1999-10-01

Infrared observations, combined with realistic laboratory simulations, have revolutionized our understanding of interstellar ice and dust, the building blocks of comets. Ices in molecular clouds are dominated by the very simple molecules H2O, CH3OH, NH3, CO, CO2, and probably H2CO and H2. More complex species including nitriles, ketones, and esters are also present, but at lower concentrations. The evidence for these, as well as the abundant, carbon-rich, interstellar, polycyclic aromatic hydrocarbons (PAHs) is reviewed. Other possible contributors to the interstellar/pre-cometary ice composition include accretion of gas-phase molecules and in situ photochemical processing. By virtue of their low abundance, accretion of simple gas-phase species is shown to be the least important of the processes considered in determining ice composition. On the other hand, photochemical processing does play an important role in driving dust evolution and the composition of minor species. Ultraviolet photolysis of realistic laboratory analogs readily produces H2, H2CO, CO2, CO, CH4, HCO, and the moderately complex organic molecules: CH3CH2OH (ethanol), HC(=O)NH2 (formamide), CH3C(=O)NH2 (acetamide), R-CN (nitriles), and hexamethylenetetramine (HMT, C6H12N4), as well as more complex species including amides, ketones, and polyoxymethylenes (POMs). Inclusion of PAHs in the ices produces many species similar to those found in meteorites including aromatic alcohols, quinones and ethers. Photon assisted PAH-ice deuterium exchange also occurs. All of these species are readily formed and are therefore likely cometary constituents.

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.

Temperature-Dependent Rate Constants and Substituent Effects for the Reactions of Hydroxyl Radicals With Three Partially Fluorinated Ethers

NASA Technical Reports Server (NTRS)

Hsu, K.-J.; DeMore, W. B.

1995-01-01

Rate constants and temperature dependencies for the reactions of OH with CF3OCH3 (HFOC-143a), CF2HOCF2H (HFOC-134), and CF3OCF2H (HFOC-125) were studied using a relative rate technique in the temperature range 298-393 K. The following absolute rate constants were derived: HFOC-143a, 1.9E-12 exp(-1555/T); HFOC-134, 1.9E-12 exp(-2006/T); HFOC-125, 4.7E-13 exp(-2095/T). Units are cm(exp 3)molecule(exp -1) s(exp -1). Substituent effects on OH abstraction rate constants are discussed, and it is shown that the CF3O group has an effect on the OH rate constants similar to that of a fluorine atom. The effects are related to changes in the C-H bond energies of the reactants (and thereby the activation energies) rather than changes in the preexponential factors. On the basis of a correlation of rate constants with bond energies, the respective D(C-H) bond strengths in the three ethers are found to be 102, 104, and 106 kcal/mol, with an uncertainty of about 1 kcal/mol.

A Black Hills-Madison Aquifer origin for Dakota Aquifer groundwater in northeastern Nebraska.

PubMed

Stotler, Randy; Harvey, F Edwin; Gosselin, David C

2010-01-01

Previous studies of the Dakota Aquifer in South Dakota attributed elevated groundwater sulfate concentrations to Madison Aquifer recharge in the Black Hills with subsequent chemical evolution prior to upward migration into the Dakota Aquifer. This study examines the plausibility of a Madison Aquifer origin for groundwater in northeastern Nebraska. Dakota Aquifer water samples were collected for major ion chemistry and isotopic analysis ((18)O, (2)H, (3)H, (14)C, (13)C, (34)S, (18)O-SO(4), (87)Sr, (37)Cl). Results show that groundwater beneath the eastern, unconfined portion of the study area is distinctly different from groundwater sampled beneath the western, confined portion. In the east, groundwater is calcium-bicarbonate type, with delta(18)O values (-9.6 per thousand to -12.4 per thousand) similar to local, modern precipitation (-7.4 per thousand to -10 per thousand), and tritium values reflecting modern recharge. In the west, groundwater is calcium-sulfate type, having depleted delta(18)O values (-16 per thousand to -18 per thousand) relative to local, modern precipitation, and (14)C ages 32,000 to more than 47,000 years before present. Sulfate, delta(18)O, delta(2)H, delta(34)S, and delta(18)O-SO(4) concentrations are similar to those found in Madison Aquifer groundwater in South Dakota. Thus, it is proposed that Madison Aquifer source water is also present within the Dakota Aquifer beneath northeastern Nebraska. A simple Darcy equation estimate of groundwater velocities and travel times using reported physical parameters from the Madison and Dakota Aquifers suggests such a migration is plausible. However, discrepancies between (14)C and Darcy age estimates indicate that (14)C ages may not accurately reflect aquifer residence time, due to mixtures of varying aged water.

Crown Ether Complexes of Alkali-Metal Chlorides from SO2.

PubMed

Reuter, Kirsten; Rudel, Stefan S; Buchner, Magnus R; Kraus, Florian; von Hänisch, Carsten

2017-07-18

The structures of alkali-metal chloride SO 2 solvates (Li-Cs) in conjunction with 12-crown-4 or 1,2-disila-12-crown-4 show strong discrepancies, despite the structural similarity of the ligands. Both types of crown ethers form 1:1 complexes with LiCl to give [Li(1,2-disila-12-crown-4)(SO 2 Cl)] (1) and [Li(12-crown-4)Cl]⋅4 SO 2 (2). However, 1,2-disila-12-crown-4 proved unable to coordinate cations too large for the cavity diameter, for example, by the formation of sandwich-type complexes. As a result, 12-crown-4 reacts exclusively with the heavier alkali-metal chlorides NaCl, KCl and RbCl. Compounds [Na(12-crown-4) 2 ]Cl⋅4 SO 2 (3) and [M(12-crown-4) 2 (SO 2 )]Cl⋅4 SO 2 (4: M=K; 5: M=Rb) all showed S-coordination to the chloride ions through four SO 2 molecules. Compounds 4 and 5 additionally exhibit the first crystallographically confirmed non-bridging O,O'-coordination mode of SO 2 . Unexpectedly, the disila-crown ether supports the dissolution of RbCl and CsCl in the solvent and gives the homoleptic SO 2 -solvated alkali-metal chlorides [MCl⋅3 SO 2 ] (6: M=Rb; 7: M=Cs), which incorporate bridging μ-O,O'-coordinating moieties and the unprecedented side-on O,O'-coordination mode. All compounds were characterised by single-crystal X-ray diffraction. The crown ether complexes were additionally studied by using NMR spectroscopy, and the presence of SO 2 at ambient temperature was revealed by IR spectroscopy of the neat compounds. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Transport and Diffusion Model for Smoke Munitions.

DTIC Science & Technology

1979-08-01

oo cri r^ <a- CM «1- »*■ l-H CO in en oo in cri vo Tt 4- CO CO i-) CM tD Z LU —I ts Z O LU Z2 O _l Q (_> =3 O LU _l S» O I-H I...DX * ^ Pox -xceMTPOO/^*^11-) + DY*CP(»y - ycr»JTP(^J)/<SVdti- s = -BA t- apis- zstA/Jj/JiCr))1’ ct = C--^*cJ //=• ^cc - ue. -zr) GO TD s5?? P...50 FORMAT(1101 PRINT m.NRPV 14 FORMAT! IHQ , •NUMBER Of ROUNDS PER VOLLEY ’.It/ ? IHO.-IDEAL IMPACT POINTS •/ ’ •O".’ NO. •,6X

Stable divalent germanium, tin and lead amino(ether)-phenolate monomeric complexes: structural features, inclusion heterobimetallic complexes, and ROP catalysis.

PubMed

Wang, Lingfang; Roşca, Sorin-Claudiu; Poirier, Valentin; Sinbandhit, Sourisak; Dorcet, Vincent; Roisnel, Thierry; Carpentier, Jean-François; Sarazin, Yann

2014-03-21

Stable germanium(II) and lead(II) amido complexes {LO(i)}M(N(SiMe3)2) (M = Ge(II), Pb(II)) bearing amino(ether)phenolate ligands are readily available using the proteo-ligands {LO(i)}H of general formula 2-CH2NR2-4,6-tBu2-C6H2OH (i = 1, NR2 = N((CH2)2OCH3)2; i = 2, NR2 = NEt2; i = 3, NR2 = aza-15-crown-5) and M(N(SiMe3)2)2 precursors. The molecular structures of these germylenes and plumbylenes, as well as those of {LO(3)}GeCl, {LO(3)}SnCl and of the congeneric {LO(4)}Sn(II)(N(SiMe3)2) where NR2 = aza-12-crown-4, have been determined crystallographically. All complexes are monomeric, with 3-coordinate metal centres. The phenolate systematically acts as a N^O(phenolate) bidentate ligand, with no interactions between the metal and the O(side-arm) atoms in these cases (for {LO(1)}(-), {LO(3)}(-) and {LO(4)}(-)) where they could potentially arise. For each family, the lone pair of electrons essentially features ns(2) character, and there is little, if any, hybridization of the valence orbitals. Heterobimetallic complexes {LO(3)}M(N(SiMe3)2)·LiOTf, where the Li(+) cation sits inside the tethered crown-ether, were prepared by reaction of {LO(3)}M(N(SiMe3)2) and LiOTf (M = Ge(II), Sn(II)). The inclusion of Li(+) (featuring a close contact with the triflate anion) in the macrocycle bears no influence on the coordination sphere of the divalent tetrel element. In association with iPrOH, the amido germylenes, stannylenes and plumbylenes catalyse the controlled polymerisation of L- and racemic lactide. The activity increases linearly according to Ge(II) ≪ Sn(II) ≪ Pb(II). The simple germylenes generate very sluggish catalysts, but the activity is significantly boosted if the heterobimetallic complex {LO(3)}Ge(N(SiMe3)2)·LiOTf is used instead. On the other hand, with 10-25 equiv. of iPrOH, the plumbylenes afford highly active binary catalysts, converting 1000 or 5000 equiv. of monomer at 60 °C within 3 or 45 min, respectively, in a controlled fashion.

Synthesis and reactivity of mononuclear iron models of [Fe]-hydrogenase that contain an acylmethylpyridinol ligand.

PubMed

Hu, Bowen; Chen, Dafa; Hu, Xile

2014-02-03

[Fe]-hydrogenase has a single iron-containing active site that features an acylmethylpyridinol ligand. This unique ligand environment had yet to be reproduced in synthetic models; however the synthesis and reactivity of a new class of small molecule mimics of [Fe]-hydrogenase in which a mono-iron center is ligated by an acylmethylpyridinol ligand has now been achieved. Key to the preparation of these model compounds is the successful C-O cleavage of an alkyl ether moiety to form the desired pyridinol ligand. Reaction of solvated complex [(2-CH2CO-6-HOC5H3N)Fe(CO)2(CH3CN)2](+)(BF4)(-) with thiols or thiophenols in the presence of NEt3 yielded 5-coordinate iron thiolate complexes. Further derivation produced complexes [(2-CH2CO-6-HOC5H3N)Fe(CO)2(SCH2CH2OH)] and [(2-CH2CO-6-HOC5H3N)Fe(CO)2(CH3COO)], which can be regarded as models of FeGP cofactors of [Fe]-hydrogenase extracted by 2-mercaptoethanol and acetic acid, respectively. When the derivative complexes were treated with HBF4 ⋅Et2O, the solvated complex was regenerated by protonation of the thiolate ligands. The reactivity of several models with CO, isocyanide, cyanide, and H2 was also investigated. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Tensile properties of V-Cr-Ti alloys after exposure in oxygen-containing environments

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

Natesan, K.; Soppet, W.K.

A systematic study was conducted to evaluate the oxidation kinetics of V-4Cr-4Ti (44 alloy) and V-5Cr-5Ti alloys (55 alloy) and to establish the role of oxygen ingress on the tensile behavior of the alloys at room temperature and at 500 C. The oxidation rate of the 44 alloy is slightly higher than that of the 55 alloy. The oxidation process followed parabolic kinetics. Maximum engineering stress for 55 alloy increased with an increase in oxidation time at 500 C. The maximum stress values for 55 alloy were higher at room temperature than ta 500 C for the same oxidation treatment.more » Maximum engineering stresses for 44 alloy were substantially lower than those for 55 alloy in the same oxidation {approx}500 h exposure in air at 500 C; the same values were 4.8 and 6.1%, respectively, at 500 C after {approx}2060 h oxidation in air at 500 C. Maximum engineering stress for 44 alloy at room temperature was 421.6--440.6 MPa after {approx}250 h exposure at 500 C in environments with a pO{sub 2} range of 1 {times} 10{sup {minus}6} to 760 torr. The corresponding uniform and total elongation values were 11--14.4% and 14.5--21.7%, respectively. Measurements of crack depths in various specimens showed that depth is independent of pO{sub 2} in the preexposure environment and was of 70--95 {micro}m after 250--275 h exposure at 500 C.« less

Detection of interstellar ethylene oxide (c-C2H4O).

PubMed

Dickens, J E; Irvine, W M; Ohishi, M; Ikeda, M; Ishikawa, S; Nummelin, A; Hjalmarson, A

1997-11-10

We report the identification of 10 transitions that support the detection of the small cyclic molecule ethylene oxide (c-C2H4O) in Sgr B2N. Although one of these transitions is severely blended, so that an accurate intensity and line width could not be determined, and two other lines are only marginally detected, we have done Gaussian fits to the remaining seven lines and have performed a rotation diagram analysis. Our results indicate a rotation temperature T(rot) = 18 K and a molecular column density N(c-C2H4O) = 3.3 x 10(14) cm-2, corresponding to a fractional abundance relative to molecular hydrogen of order 6 x 10(-11). This is a factor of more than 200 higher than the abundance for this molecule suggested by the "new standard" chemistry model of Lee, Bettens, & Herbst. This result suggests that grain chemistry might play an effective role in the production of c-C2H4O. No transitions of this molecule were detected in either Sgr B2M or Sgr B2NW.

4,5,7,8,17-Penta-hydr-oxy-14,18-dimethyl-6-methyl-ene-3,10-dioxapenta-cyclo-[9.8.0.0.0.0]nona-dec-14-ene-9,16-dione methanol solvate dihydrate.

PubMed

Teh, Chin Hoe; Teoh, Siew Chin; Yeap, Chin Sing; Chan, Kit Lam; Fun, Hoong-Kun

2009-03-28

The title quassinoid compound, C(20)H(24)O(9)·CH(3)OH·2H(2)O, is a natural eurycomanone isolated from the roots of Eurycoma longifolia. The mol-ecules contain a fused five-ring system, with one tetra-hydro-furan ring adopting an envelope conformation, one tetra-hydro-pyran-2-one ring in a screw boat conformation, one cyclo-hexenone ring in a half-chair conformation and two cyclo-hexane rings in chair conformations. Intra-molecular C-H⋯O inter-actions generate S(5) ring motifs and an O-H⋯O inter-action generates an S(7) ring motif. In the crystal, mol-ecules are linked via inter-molecular O-H⋯O inter-actions along the b axis and further stacked along a axis. The absolute configuration of the title compound was inferred from previously solved structures of its analogues.

Acculturation Indices as a Means of Confirming Cultural Differences. Navy Recruit’s Expectations of Productivity, Liking, and Intentions to Quit under Different Supervisors.

DTIC Science & Technology

1983-11-01

C )a IaI Ř aa 36 14 14 o* f iAt NJ *. 4 I E .3 .4 .4 C4 CE .4.4CE @ . ev 13.4 *0 a 4**m r m...NA C 0407 / /1 N 0 E ,. E hh IDETEhEEhE L.6 1.8:(1111_25 JllO MICROCOPY RESOLUTION TEST CHART NATIONAL SuRfAL) PA ,JANDARD t A PERSONNEL TECHNOLOGY 00...A MEANS OF CONFIRMING CULTURAL DIFFERENCES H. C . Triandis, Y. Kashima, E . Shimada & M. Villareal Technical Report ONR-27 NAVY RECRUIT’S

Four N(7)-benzyl-substituted 4,5,6,7-tetrahydro-1H-pyrazolo[3,4-b]pyridine-5-spiro-1'-cyclohexane-2',6'-diones as ethanol hemisolvates: similar molecular constitutions but different crystal structures.

PubMed

Cruz, Silvia; Trilleras, Jorge; Cobo, Justo; Low, John N; Glidewell, Christopher

2008-12-01

3-tert-Butyl-7-(4-chlorobenzyl)-4',4'-dimethyl-1-phenyl-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-b]pyridine-5-spiro-1'-cyclohexane-2',6'-dione ethanol hemisolvate, C(30)H(34)ClN(3)O(2) x 0.5C(2)H(6)O, (I), its 7-(4-bromobenzyl)- analogue, C(30)H(34)BrN(3)O(2) x 0.5C(2)H(6)O, (II), and its 7-(4-methylbenzyl)- analogue, C(31)H(37)N(3)O(2) x 0.5C(2)H(6)O, (III), are isomorphous, with the ethanol component disordered across a twofold rotation axis in the space group C2/c. In the corresponding 7-[4-(trifluoromethyl)benzyl]- compound, C(31)H(34)F(3)N(3)O(2) x 0.5C(2)H(6)O, (IV), the ethanol component is disordered across a centre of inversion in the space group P\\overline{1}. In each of (I)-(IV), the reduced pyridine ring adopts a half-chair conformation. The heterocyclic components in (I)-(III) are linked into centrosymmetric dimers by a single C-H...pi interaction, with the half-occupancy ethanol component linked to the dimer by a combination of C-H...O and O-H...pi(arene) hydrogen bonds. The heterocyclic molecules in (IV) are linked into chains of centrosymmetric rings by C-H...O and C-H...pi hydrogen bonds, again with the half-occupancy ethanol component pendent from the chain. The significance of this study lies in the isomorphism of the related derivatives (I)-(III), in the stoichiometric hemisolvation by ethanol, where the disordered solvent molecule is linked to the heterocyclic component by a two-point linkage, and in the differences between the crystal structures of (I)-(III) and that of (IV).

Soot Surface Oxidation in Laminar Hydrocarbon/Air Diffusion Flames at Atmospheric Pressure. Appendix I

NASA Technical Reports Server (NTRS)

Xu, F.; El-Leathy, A. M.; Kim, C. H.; Faeth, G. M.; Yuan, Z.-G. (Technical Monitor); Urban, D. L. (Technical Monitor); Yuan, Z.-G. (Technical Monitor)

2003-01-01

Soot surface oxidation was studied experimentally in laminar hydrocarbon/air diffusion flames at atmospheric pressure. Measurements were carried out along the axes of round fuel jets burning in coflowing dry air considering acetylene-nitrogen, ethylene, propyiene-nitrogen, propane and acetylene-benzene-nitrogen in the fuel stream. Measurements were limited to the initial stages of soot oxidation (carbon consumption less than 70%) where soot oxidation occurs at the surface of primary soot particles. The following properties were measured as a function of distance above the burner exit: soot concentrations by deconvoluted laser extinction, soot temperatures by deconvoluted multiline emission, soot structure by thermophoretic sampling and analysis using Transmission Electron Microscopy (TEM), concentrations of major stable gas species (N2, H2O, H2, O2, CO, CO2, CH4, C2H2, C2H6, C3H6, C3H8, and C6H6) by sampling and gas chromatography, concentrations of some radical species (H, OH, O) by deconvoluted Li/LiOH atomic absorption and flow velocities by laser velocimetry. For present test conditions, it was found that soot surface oxidation rates were not affected by fuel type, that direct rates of soot surface oxidation by O2 estimated from Nagle and Strickland-Constable (1962) were small compared to observed soot surface oxidation rates because soot surface oxidation was completed near the flame sheet where O2 concentrations were less than 3% by volume, and that soot surface oxidation rates were described by the OH soot surface oxidation mechanism with a collision efficiency of 0.14 and an uncertainty (95% confidence) of +/- 0.04 when allowing for direct soot surface oxidation by O2, which is in reasonably good agreement with earlier observations of soot surface oxidation rates in both premixed and diffusion flames at atmospheric pressure.

Bi2(IO3)(IO6): First combination of [IO3]- and [IO6]5- anions in three-dimensional framework

NASA Astrophysics Data System (ADS)

Sun, Chuanling; Wu, Yuandong; Mei, Dajiang; Doert, Thomas

2018-03-01

A new bismuth (III) iodate periodate, Bi2(IO3)(IO6) was obtained from hydrothermal reactions using Bi(NO3)3·5H2O, and H5IO6 as starting materials. Bi2(IO3)(IO6) crystallizes in the monoclinic space group P21/c (No. 14) with lattice parameters ɑ = 8.1119(6), b = 5.4746(4), c = 16.357(1) Å, β = 99.187(2)°, V = 717.07(9) Å3, Z = 4. The structure of Bi2(IO3)(IO6) features a three-dimensional framework which is a combination of [Bi(1)O5] tetragonal pyramids, [Bi(2)O8] bicapped trigonal prisms and [IO3]- and [IO6]5- anions. Thermal analysis shows that the compound is thermally stable up to about 350 °C. The solid state UV-vis-NIR diffuse reflectance spectrum indicates that Bi2(IO3)(IO6) is a semiconductor with a band gap of 2.76 eV.

Crystallographic study of three coronary vasodilators of the nitrate ester type: 1,4- trans-cyclohexanedimethanol dinitrate, 1,4:3,6-dianhydro- D-glucitol-2,5-dinitrate and 1,4:3,6-dianhydro- D-glucitol-2-mononitrate

NASA Astrophysics Data System (ADS)

Kanters, J. A.; Schouten, A.; Sterk, G. J.; de Jong, M. H.

1993-10-01

The crystal structures of three vasodilators of the nitrate ester type have been determined by X-ray diffraction. Compound I, 1,4- trans-cyclohexanedimethanol dinitrate (CDDN), C 8H 14N 2O 6, is a recently developed nitrate ester with a promising haemodynamic profile in the treatment of ischaemic heart diseases. CDDN crystallizes in space group P2 1/a with a = 5.9443(4), b = 16.7052(9), c = 6.2022(2) Å, β = 116.669(4)°, Z = 2 and T = 295 K. The molecule lies on a centre of inversion and the structure refined to R = 0.042 for 991 reflections with I > 2.5σ( I). The cyclohexane ring approaches an ideal chair conformation and the C-O-NO 2 fragment is strictly planar. Compound II is the widely applied vasodilator in angina pectoris, isosorbide dinitrate or 1,4:3,6-dianhydro- D-glucitol-2,5-dinitrate (ISDN), C 6H 8N 2O 8. ISDN crystallizes in space group P22 12 1 with a = 5.7535(2), b = 10.9393(5), c = 14.6599(5)Å, Z = 4 and T = 295 K. The structure refined to R = 0.033 for 1104 reflections with I > 2.5σ( I). The molecular skeleton consists of two cis-fused five-membered rings, which each adopt an envelope conformation such that the torsion angels about the central CC bond are 0.3(2) and -7.8(2)°. The angle between the rings is 60.8(1)° and the two nitrate groups are planar. Compound III, isosorbide-2-mononitrate or 1,4:3,6-dianhydro- D-glucitol-2-mononitrate (IS-2MN), C 6H 9NO 6, is an active metabolite of II and crystallizes in space group P2 12 12 1 with a = 6.4318(4), b = 7.5273(4), c = 15.866(1)Å Z = 4 and T = 100 K. The structure refined to R = 0.031 for 1488 reflections with I > 2.5σ( I). The skeleton of III is very similar to that of II. The torsion angles about the central CC bond are 2.4(2) and -3.1(2)°, the interplanar angle is 61.5(1)° and the nitrate group is strictly planar.

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

Synthesis and properties of 4-alkoxy-2-[2-hydroxy-3-(4-o,m,p-halogenoaryl-1 -piperazinyl)propyl]-6-methyl-1H-pyrrolo-[3,4-c]pyridine-1,3(2H)-diones with analgesic and sedative activities.

PubMed

Sladowska, Helena; Sabiniarz, Aleksandra; Szkatuła, Dominika; Filipek, Barbara; Sapa, Jacek

2006-01-01

Synthesis of N-substituted derivatives of 4-alkoxy-6-methyl-1H-pyrrolo[3,4-c]pyridine-1,3(2H)-diones (17-26) is described. The chlorides, containing OH group, used in the above synthesis can exist in two isomeric forms: chain (12, 14-16) and cyclic (12a, 14a-16a). All final imides studied exhibited analgesic activity in the "writhing syndrome" test which was superior than that of acetylsalicylic acid. In the "hot plate" test only two compounds (19, 20) were active as antinociceptive agents. Furthermore, all compounds tested significantly suppressed the spontaneous locomotor activity of mice.

Ilyukhinite (H3O,Na)14Ca6Mn2Zr3Si26O72(OH)2 • 3H2O, a New Mineral of the Eudialyte Group

NASA Astrophysics Data System (ADS)

Chukanov, N. V.; Rastsvetaeva, R. K.; Rozenberg, K. A.; Aksenov, S. M.; Pekov, I. V.; Belakovsky, D. I.; Kristiansen, R.; Van, K. V.

2017-12-01

A new eudialyte-group mineral, ilyukhinite, ideally (H3O,Na)14Ca6Mn2Zr3Si26O72(OH)2 · 3H2O, has been found in peralkaline pegmatite at Mt. Kukisvumchorr, Khibiny alkaline pluton, Kola Peninsula, Russia. It occurs as brownish orange, with vitreous luster anhedral grains up to 1 mm across in hydrothermally altered peralkaline rock, in association with aegirine, murmanite, albite, microcline, rhabdophane-(Ce), fluorite, sphalerite and molybdenite. The Mohs hardness is 5; cleavage is not observed. D meas 2.67(2), D calc 2.703 g/cm3. Ilyukhinite is optically uniaxial (-): ω = 1.585(2), ɛ = 1.584(2). The IR spectrum is given. The average chemical composition of ilyukhinite (wt %; electron microprobe, ranges given in parentheses; H2O determined by gas chromatography) is as follows: 3.07 (3.63-4.43) Na2O, 0.32 (0.28-0.52) K2O, 10.63 (10.26-10.90) CaO, 3.06 (2.74-3.22) MnO, 1.15 (0.93-1.37) FeO, 0.79 (0.51-0.89) La2O3, 1.21 (0.97-1.44) Ce2O3, 0.41 (0.30-0.56) Nd2O3, 0.90 (0.77-1.12) TiO2, 10.94 (10.15-11.21) ZrO2, 1.40 (0.76-1.68) Nb2O5, 51.24 (49.98-52.28) SiO2, 1.14 (0.89-1.37) SO3, 0.27 (0.19—0.38) Cl, 10.9(5 )H2O,-0.06-O = C1, total is 98.27. The empirical formula is H36.04(Na3.82K0.20)(Ca5.65Ce0.22La0.14Nd0.07)(Mn1.285Fe0.48)(Zr2.645Ti0.34)Nb0.31Si25.41S0.42Cl0.23O86.82. The crystal structure has been solved ( R = 0.046). Ilyukhinite is trigonal, R3 m; a = 14.1695(6) Å, b = 31.026(1) Å, V = 5394.7(7) Å3, Z = 3. The strongest XRD reflections [ d, Å (I, %) ( hkl)] are 11.44 (82) (101), 7.09 (70) (110), 6.02 (44) (021), 4.371 (89) 205), 3.805 (47) (303, 033), 3.376 (41) (131), 2.985 (100) (315, 128), 2.852 (92) (404). Ilyukhinite was named in memory of Vladimir V. Ilyukhin (1934-1982), an outstanding Soviet crystallographer. The type specimen of ilyukhinite has been deposited in the collection of the Natural History Museum, University of Oslo, Norway.

Quantitative evaluation of the effect of H2O degassing on the oxidation state of magmas

NASA Astrophysics Data System (ADS)

Lange, R. A.; Waters, L.

2014-12-01

The extent to which degassing of the H2O component affects the oxidation state of hydrous magmas is widely debated. Several researchers have examined how degassing of mixed H-C-O-S-Cl fluids may change the Fe3+/FeT ratio of various magmas, whereas our focus is on the H2O component. There are two ways that degassing of H2O by itself may cause oxidation: (1) the reaction: H2O (melt) + 2FeO (melt) = H2 (fluid) + Fe2O3 (melt), and/or (2) if dissolved water preferentially enhances the activity of ferrous vs. ferric iron in magmatic liquids. In this study, a comparison is made between the pre-eruptive oxidation states of 14 crystal-poor, jet-black obsidian samples (obtained from two Fe-Ti oxides) and their post-eruptive values (analyzed with the Wilson 1960 titration method tested against USGS standards). The obsidians are from Medicine Lake (CA), Long Valley (CA), and the western Mexican arc; all have low FeOT (1.1-2.1 wt%), rendering their Fe2+/Fe3+ ratios highly sensitive to the possible effects of substantial H2O degassing. The Fe-Ti oxide thermometer/oxybarometer of Ghiorso and Evans, (2008) gave temperatures for the 14 samples that range for 720 to 940°C and ΔNNO values of -0.9 to +1.4. With temperature known, the plagioclase-liquid hygrometer was applied and show that ≤ 6.5 wt% H2O was dissolved in the melts prior to eruption. In addition, pre-eruptive Cl and S concentrations were constrained on the basis of apatite analyses (Webster et al., 2009) and sulfur concentrations needed for saturation with pyrrhotite (Clemente et al., 2004), respectively. Maximum pre-eruptive chlorine and sulfur contents are 6000 and 200 ppm, respectively. After eruption, the rhyolites lost nearly all of their volatiles. Our results indicate no detectable change between pre- and post-eruptive Fe2+ concentrations, with an average deviation of ± 0.1 wt % FeO. Although degassing of large concentrations of S and/or Cl may affect the oxidation state of magmas, at the pre-eruptive levels in these 14 rhyolitic magmas, no effect is detected. Therefore, it can be robustly concluded that degassing of substantial amounts of the H2O component (≤ 6.5 wt%), by itself, does not induce oxidation in erupted magmas, particularly those more iron-rich than rhyolites (e.g., arc basalts).

Energy dependence of radiation interaction parameters of some organic compounds

NASA Astrophysics Data System (ADS)

Singh, Mohinder; Tondon, Akash; Sandhu, B. S.; Singh, Bhajan

2018-04-01

Gamma rays interact with a material through photoelectric absorption, Compton scattering, Rayleigh scattering and Pair production in the intermediate energy range. The probability of occurrence of a particular type of process depends on the energy of incident gamma rays, atomic number of the material, scattering angle and geometrical conditions. Various radiological parameters for organic compounds, namely ethylene glycol (C2H6O2), propylene glycol (C3H8O2), glycerin (C3H8O3), isoamyl alcohol (C5H12O), butanone (C4H8O), acetophenone (C8H8O2), cyclohexanone (C6H10O), furfural (C5H4O2), benzaldehyde (C7H6O), cinnamaldehyde (C9H8O), glutaraldehyde (C5H8O2), aniline (C6H7N), benzyl amine (C6H7N), nitrobenzene (C6H5NO2), ethyl benzene (C8H10), ethyl formate (C3H6O2) and water (H2O) are presented at 81, 122, 356 and 511 keV energies employing NaI(Tl) scintillation detector in narrow-beam transmission geometry. The radiation interaction parameters such as mass attenuation, molar extinction and mass energy absorption coefficients, half value layer, total atomic and effective electronic cross-sections and CT number have been evaluated for these organic compounds. The general trend of values of mass attenuation coefficients, half value layer, molar extinction coefficients, total atomic and effective electronic cross-sections and mass energy absorption coefficients shows a decrease with increase in incident gamma photon energy. The values of CT number are found to increases linearly with increase of effective atomic number (Zeff). The variation in CT number around Zeff ≈ 3.3 shows the peak like structure with respect to water and the correlation between CT number and linear attenuation coefficient is about 0.99. Appropriate equations are fitted to these experimentally determined parameters for the organic compounds at incident photon energy ranging from 81 keV to 511 keV used in the present study. Experimental values are compared with the theoretical data obtained using WinXcom software package, and are found in good agreement.

Sensitive and selective cataluminescence-based sensor system for acetone and diethyl ether determination.

PubMed

Wang, Qihui; Li, Bo; Wang, Yuhuai; Shou, Zhouxiang; Shi, Guolong

2015-05-01

A three-dimensional hierarchical CdO nanostructure with a novel bio-inspired morphology is reported. The field emission scanning electronic microscopy, transmission electron microscopy and X-ray diffractometer were employed to characterize the as-prepared samples. In gas-sensing measurements, acetone and diethyl ether were employed as target gases to investigate cataluminescence (CTL) sensing properties of the CdO nanostructure. The results show that the as-fabricated CdO nanostructure exhibited outstanding CTL properties such as stable intensity, high signal/noise values, short response and recovery time. The limit of detection of acetone and diethyl ether was ca. 6.5 ppm and 6.7 ppm, respectively, which was below the standard permitted concentrations. Additionally, a principal components analysis method was used to investigate the recognizable ability of the CTL sensor, and it was found that acetone and diethyl ether can be distinguished clearly. The performance of the bio-inspired CdO nanostructure-based sensor system suggested the promising application of the CdO nanostructure as a novel highly efficient CTL sensing material. Copyright © 2014 John Wiley & Sons, Ltd.

Tandem intramolecular silylformylation and silicon-assisted cross-coupling reactions. synthesis of geometrically defined alpha,beta-unsaturated aldehydes.

PubMed

Denmark, Scott E; Kobayashi, Tetsuya

2003-06-27

The palladium- and copper-catalyzed cross-coupling reactions of cyclic silyl ethers with aryl iodides are reported. Silyl ethers 3 were readily prepared by intramolecular silylformylation of homopropargyl silyl ethers 2 under a carbon monoxide atmosphere. The reaction of cyclic silyl ethers 3with various aryl iodides 7 in the presence of [(allyl)PdCl](2), CuI, a hydrosilane, and KF.2H(2)O in DMF at room temperature provided the alpha,beta-unsaturated aldehyde coupling products 8 in high yields. The need for copper in this process suggested that transmetalation from silicon to copper is an important step in the mechanism. Although siloxane 3 and the product 8 are not stable under basic conditions, KF.2H(2)O provided the appropriate balance of reactivity toward silicon and reduced basicity. The addition of a hydrosilane to [(allyl)PdCl](2) was needed to reduce the palladium(II) to the active palladium(0) form.

Synthesis, characterization and some properties of mononuclear Ni and trinuclear NiFe2 complexes related to the active site of [NiFe]-hydrogenases.

PubMed

Song, Li-Cheng; Sun, Xiao-Jing; Zhao, Pei-Hua; Li, Jia-Peng; Song, Hai-Bin

2012-08-07

The [N(2)S(2)]-type ligand 1,2-(2-C(5)H(4)NCH(2)S)(2)C(6)H(4) (L) is prepared in 84% yield by a new method and its structure has been confirmed by X-ray crystallography. The new synthetic method involves sequential reaction of 1,2-phenylenedithiol with EtONa followed by treatment of the resulting disodium salt of 1,2-phenylenedithiol with in situ generated 2-(chloromethyl)pyridine from its HCl salt. Further treatment of ligand L with NiCl(2)·6H(2)O or NiI(2) affords the expected new mononuclear Ni complexes Ni[1,2-(2-C(5)H(4)NCH(2)S)(2)C(6)H(4)]Cl(2) (1) and Ni[1,2-(2-C(5)H(4)NCH(2)S)(2)C(6)H(4)]I(2) (3) in 87-88% yields, whereas reaction of L with NiBr(2) under similar conditions results in formation of the expected new mononuclear complex Ni[1,2-(2-C(5)H(4)NCH(2)S)(2)C(6)H(4)]Br(2) (2) and one unexpected new mononuclear complex Ni[1-(2-C(5)H(4)NCH(2)S)-2-(2-C(5)H(4)NCH(2)SC(6)H(4)S)C(6)H(4)]Br(2) (2*) in 82% and 5% yields, respectively. More interestingly, the ligand L-containing novel trinuclear NiFe(2) complex Ni{[1,2-(2-C(5)H(4)NCH(2)S)(2)C(6)H(4)}Fe(2)(CO)(6)(μ(3)-S)(2) (4) is found to be prepared by sequential reaction of (μ-S(2))Fe(2)(CO)(6) with Et(3)BHLi, followed by treatment of the resulting (μ-LiS)(2)Fe(2)(CO)(6) with mononuclear complex 1, 2, or 3 in 12-20% yields. The new complexes 1-4 and 2* are fully characterized by elemental analysis and various spectroscopies, and the crystal structures of 1, 2* and 3 as well as some electrochemical properties of 1-4 are also reported.

π-stacking and C-X...D (X = H, NO2; D = O, π) interactions in the crystal network of both C-H...N and π-stacked dimers of 1,2-bis(4-bromophenyl)-1H-benzimidazole and 2-(4-bromophenyl)-1-(4-nitrophenyl)-1H-benzimidazole.

PubMed

González-Padilla, Jazmin E; Rosales-Hernández, Martha C; Padilla-Martínez, Itzia I; García-Báez, Efren V; Rojas-Lima, Susana; Salazar-Pereda, Veronica

2014-01-01

Molecules of 1,2-bis(4-bromophenyl)-1H-benzimidazole, C19H12Br2N2, (I), and 2-(4-bromophenyl)-1-(4-nitrophenyl)-1H-benzimidazole, C19H12BrN3O2, (II), are arranged in dimeric units through C-H...N and parallel-displaced π-stacking interactions favoured by the appropriate disposition of N- and C-bonded phenyl rings with respect to the mean benzimidazole plane. The molecular packing of the dimers of (I) and (II) arises by the concurrence of a diverse set of weak intermolecular C-X...D (X = H, NO2; D = O, π) interactions.

Effects of micro-water on decomposition of the environment-friendly insulating medium C5F10O

NASA Astrophysics Data System (ADS)

Xiao, Song; Li, Yi; Zhang, Xiaoxing; Tian, Shuangshuang; Deng, Zaitao; Tang, Ju

2017-06-01

SF6 is widely used in all kinds of high-voltage electrical equipment because of its excellent insulation and arc-extinguishing performance. However, this compound leads to serious greenhouse effect, which harms the environment. Many research institutions are now actively in search of SF6 alternative gas. C5F10O has attracted much attention as an alternative gas with low global warming potential (GWP) and excellent dielectric strength. In this paper, we analyzed the possible decomposition paths of C5F10O under micro-water environment through density functional theory. We also evaluated the ionization parameters and toxicity of the decomposition products. The results show that OH• and H• produced by H2O exhibited a catalytic effect on the decomposition of C5F10O. CF4, C2F6, C3F6, C3F8, C4F10, C5F12, C6F14, C3F7COH, C3F7OH, CF3COH, C3F7H, and CF3OH were produced in the micro-water environment. Based on molecular configuration calculation, the ionization parameters of these products were inferior to perfluorocarbons, such as C3F8, leading to reduced insulation performance of the system. Moreover, CF2O and HF are hazardous to human health and equipment safety. Results will provide a basis for further study of the insulation characteristic of the C5F10O gas mixture under micro-water condition to guide the formulation of their relevant international standards prior to engineering applications.

Stabilization of Resveratrol in Blood Circulation by Conjugation to mPEG and mPEG-PLA Polymers: Investigation of Conjugate Linker and Polymer Composition on Stability, Metabolism, Antioxidant Activity and Pharmacokinetic Profile

PubMed Central

Siddalingappa, Basavaraj; Benson, Heather A. E.; Brown, David H.; Batty, Kevin T.; Chen, Yan

2015-01-01

Resveratrol is naturally occurring phytochemical with diverse biological activities such as chemoprevention, anti-inflammatory, anti-cancer, anti-oxidant. But undergoes rapid metabolism in the body (half life 0.13h). Hence Polymer conjugation utilizing different chemical linkers and polymer compositions was investigated for enhanced pharmacokinetic profile of resveratrol. Ester conjugates such as α-methoxy-ω-carboxylic acid poly(ethylene glycol) succinylamide resveratrol (MeO-PEGN-Succ-RSV) (2 and 20 kDa); MeO-PEG succinyl ester resveratrol (MeO-PEGO-Succ-RSV) (2 kDa); α-methoxy poly(ethylene glycol)-co-polylactide succinyl ester resveratrol (MeO-PEG-PLAO-Succ-RSV) (2 and 6.6kDa) were prepared by carbodiimide coupling reactions. Resveratrol-PEG ethers (2 and 5 kDa) were synthesized by alkali-mediated etherification. All polymer conjugates were fully characterized in vitro and the pharmacokinetic profile of selected conjugates was characterized in rats. Buffer and plasma stability of conjugates was dependent on polymer hydrophobicity, aggregation behavior and PEG corona, with MeO-PEG-PLAO-Succ-RSV (2 kDa) showing a 3h half-life in rat plasma in vitro. Polymer conjugates irrespective of linker chemistry protected resveratrol against metabolism in vitro. MeO-PEG-PLAO-Succ-RSV (2 kDa), Resveratrol-PEG ether (2 and 5 kDa) displayed improved pharmacokinetic profiles with significantly higher plasma area under curve (AUC), slower clearance and smaller volume of distribution, compared to resveratrol. PMID:25799413

Arylglycerol-γ-Formyl Ester as an Aromatic Ring Cleavage Product of Nonphenolic β-O-4 Lignin Substructure Model Compounds Degraded by Coriolus versicolor†

PubMed Central

Kawai, Shingo; Umezawa, Toshiaki; Higuchi, Takayoshi

1985-01-01

4-Ethoxy-3-methoxyphenylglycerol-γ-formyl ester (compound IV) was identified as a degradation product of both 4-ethoxy-3-methoxyphenylglycerol-β-syringaldehyde ether (compound I) and 4-ethoxy-3-methoxyphenylglycerol-β-2,6-dimethoxyphenyl ether (compound II) by a ligninolytic culture of Coriolus versicolor. An isotopic experiment with a 13C-labeled compound (compound II′) indicated that the formyl group of compound IV was derived from the β-phenoxyl group of β-O-4 dimer as an aromatic ring cleavage fragment. However, compound IV was not formed from 4-ethoxy-3-methoxyphenylglycerol-β-guaiacyl ether (compound III). γ-Formyl arylglycerol (compound IV) could be a precursor of 4-ethoxy-3-methoxyphenylglycerol (compound VI), because 3-(4-ethoxy-3-methoxyphenyl)-1-formyloxy propane (compound VII) was cleaved to give 3-(4-ethoxy-3-methoxyphenyl)-1-propanol (compound VIII) by C. versicolor. 4-Ethoxy-3-methoxyphenylglycerol-β,γ-cyclic carbonate (compound V), previously found as a degradation product of compound III by Phanerochaete chrysosporium (T. Umezawa, and T. Higuchi, FEBS Lett., 25:123-126, 1985), was also identified from the cultures with compound I, II, and III and degraded to give the arylglycerol (compound VI). An isotopic experiment with 13C-labeled compounds II′ and III′ indicated that the carbonate carbon of compound V was derived from the β-phenoxyl groups of β-O-4 substructure. PMID:16346950

Effect of p-amino-diphenyl ethers on hepatic microsomal cytochrome P450.

PubMed

Jiang, Huidi; Xuan, Guida

2003-09-01

The present paper aims to investigate whether p-amino-2',4'-dichlorodiphenyl ether and p-amino-4'-methyldiphenyl ether are inhibitors as well as inducers of P450. Mice were given daily intraperitoneal (ip) injections of p-amino-2',4'-dichlorodiphenyl ether (0.25 mmol/kg) or p-amino-4'-methyldiphenyl ether (0.25 mmol/kg) for 4 days and tested at 24 h and 48 h after the last dose injection. The results showed the mice pentobarbital sleeping time was shorter and the P450 content of hepatic microsome increased significantly in the group pretreated with p-amino-4'-methyldiphenyl ether when compared with the control group, while in mice pretreated with p-amino-2',4'-dichlorodiphenyl ether the hepatic microsome P450 content increased but the pentobarbital sleeping time was extended in clear contrast to the control group. The sleeping time of the phenobarbital group (80 mg/kg daily ip injection for 4 days) was shortened at 24 h after the last injection with increased P450 content of hepatic microsome, but it showed no difference at 48 h. The zoxazolamine-paralysis times of mice treated with p-amino-2',4'-dichlorodiphenyl ether were longer than those of the control mice, while the same dose of zoxazolamine did not lead to paralysis in mice pretreated with BNF. p-Amino-2',4'-dichlorodiphenyl ether and p-amino-4'-methyldiphenyl ether inhibited the activity of 7-ethoxyresorufin O-deethylase from rat hepatic microsome induced by BNF in vitro by 70.0% and 50.1% respectively. These results suggest that p-amino-2',4'-dichlorodiphenyl ether and p-amino-4'-methyldiphenyl ether are inhibitors as well as inducers of P450.

Coupled antiferromagnetic spin-1/2 chains in green dioptase, Cu6 [Si6O18.6] H2O

NASA Astrophysics Data System (ADS)

Podlesnyak, Andrey; Anovitz, L. M.; Kolesnikov, A. I.; Matsuda, M.; Prisk, T. R.; Ehlers, G.; Toth, S.

Gem crystals of natural dioptase with colors ranging from emerald-green to bluish have delighted people since ancient times and still attract attention of mineral collectors around the globe. The crystal structure of green dioptase (space group R 3) consists of corrugated silicate rings Si6O<18 interconnected by Cu2+ ions. Oxygen atoms form axially-elongated octahedral of CuO4(H2O)2. The magnetic ground state of green dioptase remains controversial. We report inelastic neutron scattering measurements of the magnetic excitations of green dioptase Cu6 [ Si6O18.6 ] H2O. The observed spectrum contains two magnetic modes and a prominent spin gap that is consistent with the ordered ground state of Cu moments coupled antiferromagnetically in spiral chains along the c axis and ferromagnetically in ab planes on the hexagonal cell. The data are in excellent agreement with a spin-1/2 Hamiltonian that includes AFM nearest-neighbor intra-chain coupling Jc = 10 . 6 (1) meV, ferromagnetic inter-chain coupling Jab = - 1 . 2 (1) meV and exchange anisotropy ΔJc = 0 . 14 (1) meV. This appears compatible with reduced Nèel temperature, TN = 14 . 5 K <

Word Frequency Analysis. MOS: 45K. Skill Levels 1 & 2.

DTIC Science & Technology

1981-05-01

ACCESSION No. 3. RECIPIENT’S CATALOG 14UMBER 4. TITLE...change. Accession For DTIC TAB [ Ux~amo~ed []Just iriction D_.st ribution, pYAvai labilit 7 codt.s A o Avi ado S* HEADQUARTERS DATA CONTROL NMEIII m...6 (’N "N 6 . "!4 ON Cf c4:’i 6 Cu-L /’Uc.RE" L ~u:ir 6 6 Z72 : SS7 2 t N 6’vy \\ .C.1F? 6 H% ’ e y N ’CIo6’ 6 A fg; 6 l~ 14 6 r I 5’J 6 ’~1!6 ’",13P 6

Effective oxidation of benzylic and alkane C-H bonds catalyzed by sodium o-iodobenzenesulfonate with Oxone as a terminal oxidant under phase-transfer conditions.

PubMed

Cui, Li-Qian; Liu, Kai; Zhang, Chi

2011-04-07

Catalytic oxidation of benzylic C-H bonds could be efficiently realized using IBS as a catalyst which was generated in situ from the oxidation of sodium 2-iodobenzenesulfonate (1b) by Oxone in the presence of a phase-transfer catalyst, tetra-n-butylammonium hydrogen sulfate, in anhydrous acetonitrile at 60 °C. Various alkylbenzenes, including toluenes and ethylbenzenes, several oxygen-containing functionalities substituted alkylbenzenes, and a cyclic benzyl ether could be efficiently oxidized. And, the same reagent system of cat. 1b/Oxone/cat. n-Bu(4)NHSO(4) could be applied to the effective oxidation of alkanes as well.

Conformational stability of the propylene oxide-water adduct: direct spectroscopic detection of O-H...O hydrogen bonded conformers.

PubMed

Su, Zheng; Wen, Qing; Xu, Yunjie

2006-05-24

The 1:1 molecular adduct of propylene oxide and water (PO-H(2)O) was studied using Fourier transform microwave spectroscopy and high level ab initio methods. Two distinct structural conformers with the water molecule acting as a proton donor were detected experimentally: one with the water on the same side as the methyl group with respect to the ether ring, i.e., syn-PO-H(2)O, the other with the water molecule binding to the O-atom from the opposite side of the methyl group, i.e., anti-PO-H(2)O. The nonbonded hydrogen is entgegen to the ether ring in both conformers. Rotational spectra of four isotopic species, namely PO-H(2)O, PO-DOH, PO-HOD, and PO-D(2)O, were recorded for the two conformers. The hydrogen bond parameters: r(O(epoxy)...H), angle(ring-O(epoxy)...H), and angle(O(epoxy)...H-O) are 1.908 A, 112 degrees, and 177 degrees for syn-PO-H(2)O, and 1.885 A, 104.3 degrees, and 161.7 degrees for anti-PO-H(2)O, respectively. The experimental results suggest that the hydrogen bond in syn-PO-H(2)O is stronger and the monomer subunits are more rigidly locked in their positions than in the ethylene oxide-water adduct. The stabilizing effect of the methyl group to the intermolecular hydrogen bond is discussed in terms of the experimentally estimated binding energies, the structural parameters, and the ab initio calculations.

Phase equilibrium measurements on twelve binary mixtures

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

Giles, N.F.; Wilson, H.L.; Wilding, W.V.

1996-11-01

Phase equilibrium measurements have been performed on twelve binary mixtures. The PTx method was used to obtain vapor-liquid equilibrium data for the following binary systems at two temperatures each: ethanethiol + propylene; nitrobenzene + methanol; pyridine + ethyl acetate; octane + tert-amyl methyl ether; diisopropyl ether + butane; 1,3-dichloro-2-propanol + epichlorohydrin; 2,3-dichloro-1-propanol + epichlorohydrin; 2,3-epoxy-1-propanol + epichlorohydrin; 3-chloro-1,2-propanediol + epichlorohydrin; methanol + hydrogen cyanide. For these systems, equilibrium vapor and liquid phase compositions were derived from the PTx data using the Soave equation of state to represent the vapor phase and the Wilson, NRTL, or Redlich-Kister activity coefficient model tomore » represent the liquid phase. The infinite dilution activity coefficient of methylamine in N-methyl-2-pyrrolidone was determined at three temperatures by performing PTx measurements on the N-methyl-2-pyrrolidone was determined at three temperatures by performing PTx measurements on the N-methyl-2-pyrrolidone-rich half of the binary. Liquid-liquid equilibrium studies were made on the triethylene glycol + 1-pentene system at two temperatures by directly analyzing samples taken from each liquid phase.« less

Carma 1 CM Line Survey of Orion-Kl

NASA Astrophysics Data System (ADS)

Friedel, Douglas; Looney, Leslie; Corby, Joanna F.; Remijan, Anthony

2015-06-01

We have conducted the first 1 cm (27-35 GHz) line survey of the Orion-KL region by an array. With a primary beam of ˜4.5 arcminutes, the survey looks at a region ˜166,000 AU (0.56 pc) across. The data have a resolution of ˜6 arcseconds on the sky and 97.6 kHz(1.07-0.84 km/s) in frequency. This region of frequency space is much less crowded than at 3mm or 1mm frequencies and contains the fundamental transitions of several complex molecular species, allowing us to probe the largest extent of the molecular emission. We present the initial results, and comparison to 3mm results, from several species including, dimethyl ether [(CH_3)_2O], ethyl cyanide [C_2H_5CN], acetone [(CH_3)_2CO], SO, and SO_2.

Using Nonequilibrium Alloying Techniques for Corrosion Inhibition in Gr/ Al and Gr/Mg Metal Matrix Composites

DTIC Science & Technology

1994-06-15

of AI-12Mg-13Sf Before and After Heat Treament at 400C for 1, 2 and 8 hre and 5000C for I hr, Polarized in Quiescent 0. IM NaCI, pH 8, 2W°C. 8 0.8 AI...C4 4R o00qI i co c cc o !00§ " 00- 0-coo 88 88-- o IMM CCO 00 PP0M 3I34 -1.2 M9 - TreaMent #1 .1.4 ~ 1.5 .7 -6 -5 -4 -3 -2 - Current Denedty, log (A

Dimethyl Sulfide-Dimethyl Ether and Ethylene Oxide-Ethylene Sulfide Complexes Investigated by Fourier Transform Microwave Spectroscopy and AB Initio Calculation

NASA Astrophysics Data System (ADS)

Kawashima, Yoshiyuki; Tatamitani, Yoshio; Mase, Takayuki; Hirota, Eizi

2015-06-01

The ground-state rotational spectra of the dimethyl sulfide-dimethyl ether (DMS-DME) and the ethylene oxide and ethylene sulfide (EO-ES) complexes were observed by Fourier transform microwave spectroscopy, and a-type and c-type transitions were assigned for the normal, 34S, and three 13C species of the DMS-DME and a-type and b-type rotational transitions for the normal, 34S, and two 13C species of the EO-ES. The observed transitions were analyzed by using an S-reduced asymmetric-top rotational Hamiltonian. The rotational parameters thus derived for the DMS-DME were found consistent with a structure of Cs symmetry with the DMS bound to the DME by two C-H(DMS)---O and one S---H-C(DME) hydrogen bonds. The barrier height V3 to internal rotation of the "free" methyl group in the DME was determined to be 915.4 (23) wn, which is smaller than that of the DME monomer, 951.72 (70) wn, and larger than that of the DME dimer, 785.4 (52) wn. For the EO-ES complex the observed data were interpreted in the terms of an antiparallel Cs geometry with the EO bound to the ES by two C-H(ES)---O and two S---H-C(EO) hydrogen bonds. We have applied a natural bond orbital (NBO) analysis to the DMS-DME and EO-ES to calculate the stabilization energy CT (= ΔEσσ*), which were closely correlated with the binding energy EB, as found for other related complexes. Y. Niide and M. Hayashi, J. Mol. Spectrosc. 220, 65-79 (2003). Y. Tatamitani, B. Liu, J. Shimada, T. Ogata, P. Ottaviani, A. Maris, W. Caminati, and J. L. Alonso, J. Am. Chem. Soc. 124, 2739-2743 (2002).

Boron Nitride and Silicon Nitride Systems

DTIC Science & Technology

1991-02-01

far Physikalische Chemie der UniversitAt W~ien, Austria February 1991 United States Army EUROPEAN RESEARCH OFFICE OF THE U.S. ARMY London England...109 A Van hPS a= 491.7 [85Vi1J PSa22 a= 458.8 I-n I~.a Vea~ad tP58 a=2a(V ) [780no] * P4,/nmc o=2a(VN ) V.~z VNIIx cp8 a= 413.6 [85Vii] Fm~m IaC1...Cr8 c= 306.5 vBU hP14 a= 298.45 [88Kle) � P6,/mmc c=1387.3 V2B5 W 1-xB, a P a= 519.76 [SeKleJ �* P8,1.30 o= 833.51 VaN cF8 a= 412.8 [85Vil) N

1,4-Iron Migration for Expedient Allene Annulations through Iron-Catalyzed C-H/N-H/C-O/C-H Functionalizations.

PubMed

Mo, Jiayu; Müller, Thomas; Oliveira, João C A; Ackermann, Lutz

2018-06-25

C-H activation bears great potential for enabling sustainable molecular syntheses in a step- and atom-economical manner, with major advances having been realized with precious 4d and 5d transition metals. In contrast, we employed earth abundant, nontoxic iron catalysts for versatile allene annulations through a unique C-H/N-H/C-O/C-H functionalization sequence. The powerful iron catalysis occurred under external-oxidant-free conditions even at room temperature, while detailed mechanistic studies revealed an unprecedented 1,4-iron migration regime for facile C-H activations. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

Kuz'mina, L. G., E-mail: kuzmina@igic.ras.ru; Gunina, M. A.; Churakov, A. V.

Two aromatic esters with the formulas C{sub 6}H{sub 13}-O-C{sub 6}H{sub 4}-C(O)O-C{sub 6}H{sub 4}-O-C{sub 7}H{sub 15} (1) and C{sub 7}H{sub 15}-O-C{sub 6}H{sub 4}-C(O)O-C{sub 6}H{sub 4}-O-C{sub 4}H{sub 9} (2) belonging to nematic liquid-crystal compounds were studied by X-ray diffraction. Compound 1 crystallizes in two modifications: monoclinic (1-m) and triclinic (1-tr). The crystal packing of 1 and 2 is built from alternating loosely packed aliphatic regions and closely packed aromatic regions. In crystal structures 1-m and 2, the aromatic regions are linked into chains by hydrogen bonds with the participation of the carbonyl oxygen atom of the ester group and the C-H fragmentmore » of the benzene ring, but these hydrogen bonds in 1-m are much weaker than in 2. In 1-m there are {pi}-stacking interactions between the molecules, resulting in the formation of centrosymmetric dimers with an interplanar distance of 3.45 A. In 1-tr, the aromatic fragments form a herringbone packing motif favorable for a two-dimensional network of directional C-H...{pi}-system interactions.« less

4-{2-[2-(4-Formyl-phen-oxy)eth-oxy]eth-oxy}benzaldehyde.

PubMed

Ma, Zhen; Cao, Yiqun

2011-06-01

The title compound, C(18)H(18)O(5), was obtained by the reaction of 4-hy-droxy-benzaldehyde with bis-(2,2-dichloro-eth-yl) ether in dimethyl-formamide. In the crystal, the mol-ecule lies on a twofold rotation axis that passes through the central O atom of the aliphatic chain, thus leading to one half-mol-ecule being present per asymmetric unit. The carbonyl, aryl and O-CH(2)-CH(2) groups are almost coplanar, with an r.m.s. deviation of 0.030 Å. The aromatic rings are approximately perpendicular to each other, forming a dihedral angle of 78.31 sh;H⋯O hydrogen bonds and C-H⋯π inter-actions help to consolidate the three-dimensional network.

Anti-Helicobacter pylori activity of derivatives of the phthalide-containing antibacterial agents spirolaxine methyl ether, CJ-12,954, CJ-13,013, CJ-13,102, CJ-13,104, CJ-13,108 and CJ-13,015.

PubMed

Radcliff, Fiona J; Fraser, John D; Wilson, Zoe E; Heapy, Amanda M; Robinson, James E; Bryant, Christina J; Flowers, Christopher L; Brimble, Margaret A

2008-06-01

The naturally occurring phthalide-containing antibiotics spirolaxine methyl ether, CJ-12,954, CJ-13,013, CJ-13,015, CJ-13,102, CJ-13,103, CJ-13,104 and CJ-13,108, have been reported to exhibit anti-H. pylori activity. However, the exact stereochemistry of spirolaxine methyl ether, CJ-12,954 or CJ-13,013, contributing to this observed activity has not been confirmed. The anti-H. pylori activity of several analogues of spirolaxine methyl ether, CJ-12,954 and CJ-13,013 of defined stereochemistry together with the anti-H. pylori activity of several indole analogues of the simpler phthalide-containing antibiotics CJ-13,102, CJ-13,104, CJ-13,108 and CJ-13,015 is reported herein. A 1:1 mixture of spiroacetals 5b and 6b in which the phthalide substituent exhibited (3R)-stereochemistry was sixty times more active than the corresponding 1:1 mixture of spiroacetals with (3S)-stereochemistry. Notably, the unnatural (2''S)-diastereomer of spirolaxine methyl ether exhibited more potent anti-H. pylori activity than the natural product spirolaxine methyl ether. The 4,6-dimethoxyindoles 9, 10, 11 and 13 were all found to be less active than their parent compounds 1, 2, 3 and 4, respectively. Chain-shortened 4,6-dimethoxyindole analogue 12 of CJ-13,108 3 and 4,6-dimethoxyindole-spiroacetal 13 exhibited weak anti-H. pylori activity thus providing future opportunity for drug discovery programs.

The combination of huperzine A and imidazenil is an effective strategy to prevent diisopropyl fluorophosphate toxicity in mice.

PubMed

Pibiri, Fabio; Kozikowski, Alan P; Pinna, Graziano; Auta, James; Kadriu, Bashkim; Costa, Erminio; Guidotti, Alessandro

2008-09-16

Diisopropyl fluorophosphate (DFP) causes neurotoxicity related to an irreversible inhibition of acetylcholinesterase (AChE). Management of this intoxication includes: (i) pretreatment with reversible blockers of AChE, (ii) blockade of muscarinic receptors with atropine, and (iii) facilitation of GABA(A) receptor signal transduction by benzodiazepines. The major disadvantage associated with this treatment combination is that it must to be repeated frequently and, in some cases, protractedly. Also, the use of diazepam (DZP) and congeners includes unwanted side effects, including sedation, amnesia, cardiorespiratory depression, and anticonvulsive tolerance. To avoid these treatment complications but safely protect against DFP-induced seizures and other CNS toxicity, we adopted the strategy of administering mice with (i) small doses of huperzine A (HUP), a reversible and long-lasting (half-life approximately 5 h) inhibitor of AChE, and (ii) imidazenil (IMI), a potent positive allosteric modulator of GABA action selective for alpha(5)-containing GABA(A) receptors. Coadministration of HUP (50 microg/kg s.c., 15 min before DFP) with IMI (2 mg/kg s.c., 30 min before DFP) prevents DFP-induced convulsions and the associated neuronal damage and mortality, allowing complete recovery within 18-24 h. In HUP-pretreated mice, the ED(50) of IMI to block DFP-induced mortality is approximately 10 times lower than that of DZP and is devoid of sedation. Our data show that a combination of HUP with IMI is a prophylactic, potent, and safe therapeutic strategy to overcome DFP toxicity.

The combination of huperzine A and imidazenil is an effective strategy to prevent diisopropyl fluorophosphate toxicity in mice

PubMed Central

Pibiri, Fabio; Kozikowski, Alan P.; Pinna, Graziano; Auta, James; Kadriu, Bashkim; Costa, Erminio; Guidotti, Alessandro

2008-01-01

Diisopropyl fluorophosphate (DFP) causes neurotoxicity related to an irreversible inhibition of acetylcholinesterase (AChE). Management of this intoxication includes: (i) pretreatment with reversible blockers of AChE, (ii) blockade of muscarinic receptors with atropine, and (iii) facilitation of GABAA receptor signal transduction by benzodiazepines. The major disadvantage associated with this treatment combination is that it must to be repeated frequently and, in some cases, protractedly. Also, the use of diazepam (DZP) and congeners includes unwanted side effects, including sedation, amnesia, cardiorespiratory depression, and anticonvulsive tolerance. To avoid these treatment complications but safely protect against DFP-induced seizures and other CNS toxicity, we adopted the strategy of administering mice with (i) small doses of huperzine A (HUP), a reversible and long-lasting (half-life ≈5 h) inhibitor of AChE, and (ii) imidazenil (IMI), a potent positive allosteric modulator of GABA action selective for α5-containing GABAA receptors. Coadministration of HUP (50 μg/kg s.c., 15 min before DFP) with IMI (2 mg/kg s.c., 30 min before DFP) prevents DFP-induced convulsions and the associated neuronal damage and mortality, allowing complete recovery within 18–24 h. In HUP-pretreated mice, the ED50 of IMI to block DFP-induced mortality is ≈10 times lower than that of DZP and is devoid of sedation. Our data show that a combination of HUP with IMI is a prophylactic, potent, and safe therapeutic strategy to overcome DFP toxicity. PMID:18784370

Physicochemical properties of chars at different treatment temperatures.

PubMed

Kim, Sung Su; Kang, Youn Suk; Lee, Hyun Dong; Kim, Jae Kwan; Hong, Sung Chang

2012-02-01

In this study, the physicochemical properties of the char of Indonesian SM coal following heat treatment at various temperatures were evaluated using X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and morphological and specific surface area analysis. Based on these analyses, heat treatment of coal was determined to be the most effective in increasing the coal rank. In the XPS analysis, the C-O and C-O-C groups and quaternary-N species were found to be of a lower grade coal when the pretreatment temperature decreased, meanwhile the C-C group and pyridinic species increased. In the FT-IR analysis, the collapse of the C-O and C-O-C group was observed due to the collapse of the ether group. In SEM and Brunauer-Emmett-Teller (BET) analysis, a decrease in the ether group was shown to be accompanied with the formation of micropores.

Step Stress Testing of Receiver/Transmitter Units. Part 1

DTIC Science & Technology

1993-02-01

voltage reading taken must be multiplied by 10 (as instructed on the test box) to convert to the proper milliampere (mA) reading. D- 16 018 CAUTIONII...INTERVALs4 and 5 above using VARIABLEs below. INTERVAL 6&7 8&9 10&11 12&13 14&15 16 &17 18&19 20&21 FINALVAL (oC) 85 94 102 111 119 127 135 143 INTERVAL...22.Z deg. ch~ 6 22. d. ~ch- 69 2.3ds ch- 09 11.5dgC ch- 16 22.2 d.~ _h 9 2. oSc 0 2. eg;S ch 1 2. oCch- 1a 22.3 d92_C Ch, 11 2. de;C ch- 12 22.2 dog-C

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.

Ethyl 2-(4-meth-oxy-phen-yl)-6-oxa-3-aza-bicyclo[3.1.0]hexane-3-carboxyl-ate: crystal structure and Hirshfeld analysis.

PubMed

Zukerman-Schpector, Julio; Sugiyama, Fabricia H; Garcia, Ariel L L; Correia, Carlos Roque D; Jotani, Mukesh M; Tiekink, Edward R T

2017-07-01

The title compound, C 14 H 17 NO 4 , features an epoxide-O atom fused to a pyrrolidyl ring, the latter having an envelope conformation with the N atom being the flap. The 4-meth-oxy-phenyl group is orthogonal to [dihedral angle = 85.02 (6)°] and lies to the opposite side of the five-membered ring to the epoxide O atom, while the N-bound ethyl ester group (r.m.s. deviation of the five fitted atoms = 0.0187 Å) is twisted with respect to the ring [dihedral angle = 17.23 (9)°]. The most prominent inter-actions in the crystal are of the type methine-C-H⋯O(carbon-yl) and these lead to the formation of linear supra-molecular chains along the c axis; weak benzene-C-H⋯O(epoxide) and methine-C-H⋯O(meth-oxy) inter-actions connect these into a three-dimensional architecture. The analysis of the Hirshfeld surface confirms the presence of C-H⋯O inter-actions in the crystal, but also the dominance of H⋯H dispersion contacts.

CONTROLLED METHYL TERTIARY BUTYL ETHER (MTBE) EXPOSURE TO HUMANS THROUGH DERMAL, INGESTION, AND INHALATION ROUTES AND THE RESULTANT BIOMARKER TERTIARY BUTYL ALCOHOL (TBA) AS MEASURED IN EXHALED BREATH AND VENOUS BLOOD

EPA Science Inventory

Radiocarbon (14C) measurements provide an estimate of the fraction of carbon in a sample that is biogenic. In September 1997 during SCOS97 a series of 3-h canister samples of ambient air were collected at the Azusa air monitoring station during morning and afternoon periods. ...

Efficient removal of caesium ions from aqueous solution using a calix crown ether in ionic liquids: mechanism and radiation effect.

PubMed

Xu, Chao; Yuan, Liyong; Shen, Xinghai; Zhai, Maolin

2010-04-28

The removal of radioactive (137)Cs from nuclear waste is of great importance for both the environment and energy saving. Herein, we report a study on the removal of Cs(+) using a calix crown ether bis(2-propyloxy)calix[4]crown-6 (BPC6) in ionic liquids [C(n)mim][NTf(2)], where [C(n)mim](+) is 1-alkyl-3-methylimidazolium and [NTf(2)](-) is bis(trifluoromethylsulfonyl)imide. The BPC6/[C(n)mim][NTf(2)] system is highly efficient in removing Cs(+) from aqueous solution, even at a low concentration of BPC6. HNO(3) and metal ions such as Na(+), Al(3+) in the aqueous phase interfered with the extraction of Cs(+) by competitive interaction with BPC6 and/or salting-out effect. UV analysis confirmed that the extraction of Cs(+) by the BPC6/[C(n)mim][NTf(2)] system involves a dual extraction mechanism, i.e., via exchange of BPC6.Cs(+) complex or Cs(+) by [C(n)mim](+). Irradiation of [C(4)mim][NTf(2)] dramatically decreases Cs(+) partitioning in the ionic liquid phase by the competitive interaction of radiation-generated H(+) with BPC6, while irradiation of BPC6/[C(4)mim][NTf(2)] decreases Cs(+) partitioning more markedly due to the radiolysis of BPC6.

Inhibition and induction of aromatase (CYP19) activity by brominated flame retardants in H295R human adrenocortical carcinoma cells.

PubMed

Cantón, Rocío F; Sanderson, J Thomas; Letcher, Robert J; Bergman, Ake; van den Berg, Martin

2005-12-01

Brominated flame retardants (BFRs) are persistent and ubiquitous chemicals in the environment, and they are found at increasing levels in tissues of wildlife and humans. Previous in vitro studies with the BFR class of polybrominated diphenyl ethers (BDEs) have shown endocrine-disrupting properties. Our study assessed the potential effects of nineteen BDEs, five hydroxylated BDEs (OH-BDEs), one methoxylated BDE (CH(3)O-BDE), tetrabromobisphenol-A (TBBPA), its dibromopropane ether derivative (TBBPA-DBPE), and the brominated phenols/anisols 2,4,6-tribromophenol (TBP), 4-bromophenol (4BP) and 2,4,6-tribromoanisole (TBA) on the catalytic activity of the steroidogenic enzyme aromatase (CYP19) in H295R human adrenocortical carcinoma cells. Effects were studied in the concentration range from 0.5 to 7.5 microM; exposures were for 24 h. Both 6-OH-BDE47 and 6-OH-BDE99 showed an inhibitory effect on aromatase activity at concentrations >2.5 microM and >5 microM, respectively. However, 6-OH-BDE47 also caused a statistically significant increase in cytotoxicity (based on mitochondrial MTT reduction and lactate dehydrogenase-leakage [LDH]) at concentrations >2.5 microM that could explain in part the apparent inhibitory effect on aromatase activity. Compared to 6-OH-BDE47, the methoxy analog (6-CH(3)O-BDE47) did not elicit a cytotoxic effect, whereas significant inhibition of aromatase remained. TBP caused a concentration-dependent induction of aromatase activity between 0.5 and 7.5 microM (with a maximum of 3.8-fold induction at 7.5 microM). This induction was not observed when a OH- group replaced the CH(3)O- group or when bromine atoms adjacent to this OH- group were absent. These in vitro results provide a basis for studies of more detailed structure-activity relationships between these brominated compounds and the modulation of aromatase activity.

On-site GC/MS analysis of Chapman gasification separator liquor. Final report Jul 80-Mar 81

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

Thielen, C.J.; Magee, R.A.; Collins, R.V.

1981-08-01

The report gives results of a characterization of a wastewater stream from a coal gasification plant, using on-site extraction and GC/MS analysis. Extractable material in the wastewater was primarily phenols and alkylphenols, accounting for about 99% of the total mass identified. Several polynuclear aromatic compounds were also identified. The composition of the sample deteriorated even though the water was held in amber bottles at 4C: this was most evident in the concentration of dimethylphenols which dropped about 75% during 2 weeks of refrigerated storage. Ambient sample storage produced a greater decrease in the concentration of phenol, but did not appearmore » to affect the alkylphenols or the base/neutral compounds as much. The observed changes in composition should hamper any off-site wastewater treatbility studies with waters of this type. Diisopropyl ether (DIPE) extraction confirmed the 99-plus % removal efficiency of phenol which had been demonstrated in previous studies. Wet oxidation removed organics almost as efficiently as DIPE extraction, but may have limited use because of its high operating cost.« less

Synthetic and structural investigations of mercurous and mercuric organophosphonates and phenylarsonates

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

Padalwar, Nitin Balkrushna; Vidyasagar, Kanamaluru

2016-11-15

The following twelve mercurous and mercuric organophosphomates, bis/diphosphonates and phenylarsonates have been isolated and structurally characterized by single crystal X-ray diffraction, {sup 13}C-and {sup 31}P NMR, infrared and Raman spectroscopic methods: Hg{sub 2}(HO{sub 3}PC{sub 6}H{sub 5}){sub 2}(1), Hg{sub 2}(HO{sub 3}P(C{sub 6}H{sub 4})PO{sub 3}H)(2), Hg{sub 2}(HO{sub 3}P(C{sub 6}H{sub 4}){sub 2}PO{sub 3}H)(3), Hg{sub 2}(HO{sub 3}P(CH{sub 2}){sub 4}PO{sub 3}H)(4), Hg{sub 2}(O{sub 3}PC{sub 6}H{sub 5})·H{sub 2}O(5), (Hg{sub 2}){sub 2}(O{sub 3}P(CH{sub 2}){sub 2}PO{sub 3})(6), (Hg{sub 2}){sub 2}(O{sub 3}P(CH{sub 2}){sub 3}PO{sub 3})(7), Hg(O{sub 3}PC{sub 6}H{sub 5})·H{sub 2}O(8), Hg(O{sub 3}PCH{sub 2}C{sub 6}H{sub 5})·H{sub 2}O(9), Hg(O{sub 3}AsC{sub 6}H{sub 5})·H{sub 2}O(10), Hg{sub 3}(O{sub 3}AsC{sub 6}H{sub 5}){sub 2}(HO{sub 3}AsC{sub 6}H{submore » 5}){sub 2}(11) and (Hg{sub 2})Hg{sub 3}(O{sub 3}P(C{sub 6}H{sub 4})PO{sub 3}){sub 2}·2H{sub 2}O(12). Compounds 1–7 are the first examples of mercurous phosphonates and di/bisphosphonates. They contain Hg{sub 2}O{sub 6} units, which consist of Hg{sub 2}{sup 2+} cations with Hg-Hg bond of ~2.5 Å length. Phenylphosphonates 1 and 5 are layered compounds, whereas bis/diphosphonates 2, 3, 4, 6 and 7 have pillared-layered and three-dimensional structures. Compounds 8–11 are layered mercuric phosphonates and phenylarsonates. Compound 12 is a three-dimensional mixed-valent mercury phenylenebisphosphonate. - Graphical abstract: The first examples of mercurous organophosphonates and organodiphosphonates have layered, pillared-layered and three-dimensional structures.« less

Structure and Reactivity of Alkyl Ethers Adsorbed on CeO2(111) Model Catalysts

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

F Calaza; T Chen; D Mullins

2011-12-31

The effect of surface hydroxyls on the adsorption of ether on ceria was explored. Adsorption of dimethyl ether (DME) and diethyl ether (DEE) on oxidized and reduced CeO{sub 2}(111) films was studied and compared with Ru(0001) using RAIRS and sXPS within a UHV environment. On Ru(0001) the ethers adsorb weakly with the molecular plane close to parallel to the surface plane. On the ceria films, the adsorption of the ethers was stronger than on the metal surface, presumably due to stronger interaction of the ether oxygen lone pair electrons with a cerium cation. This interaction causes the ethers to tiltmore » away from the surface plane compared to the Ru(0001) surface. No pronounced differences were found between oxidized (CeO{sub 2}) and reduced (CeOx) films. The adsorption of the ethers was found to be perturbed by the presence of OH groups on hydroxylated CeOx. In the case of DEE, the geometry of adsorption resembles that found on Ru, and in the case of dimethyl ether DME is in between that one found on clean CeOx and the metal surface. Decomposition of the DEE was observed on the OH/CeOx surface following high DEE exposure at 300 K and higher temperatures. Ethoxides and acetates were identified as adsorbed species on the surface by means of RAIRS and ethoxides and formates by s-XPS. No decomposition of dimethyl ether was observed on the OH/CeOx at these higher temperatures, implying that the dissociation of the C-O bond from ethers requires the presence of {beta}-hydrogen.« less

Structure and Reactivity of Alkyl Ethers Adsorbed on CeO(2)(111) Model Catalysts

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

Calaza, Florencia C; Chen, Tsung-Liang; Mullins, David R

2011-01-01

The effect of surface hydroxyls on the adsorption of ether on ceria was explored. Adsorption of dimethyl ether (DME) and diethyl ether (DEE) on oxidized and reduced CeO{sub 2}(111) films was studied and compared with Ru(0001) using RAIRS and sXPS within a UHV environment. On Ru(0001) the ethers adsorb weakly with the molecular plane close to parallel to the surface plane. On the ceria films, the adsorption of the ethers was stronger than on the metal surface, presumably due to stronger interaction of the ether oxygen lone pair electrons with a cerium cation. This interaction causes the ethers to tiltmore » away from the surface plane compared to the Ru(0001) surface. No pronounced differences were found between oxidized (CeO{sub 2}) and reduced (CeOx) films. The adsorption of the ethers was found to be perturbed by the presence of OH groups on hydroxylated CeOx. In the case of DEE, the geometry of adsorption resembles that found on Ru, and in the case of dimethyl ether DME is in between that one found on clean CeOx and the metal surface. Decomposition of the DEE was observed on the OH/CeOx surface following high DEE exposure at 300 K and higher temperatures. Ethoxides and acetates were identified as adsorbed species on the surface by means of RAIRS and ethoxides and formates by s-XPS. No decomposition of dimethyl ether was observed on the OH/CeOx at these higher temperatures, implying that the dissociation of the C-O bond from ethers requires the presence of {beta}-hydrogen.« less

Synthesis, Structure, and Thermal Properties of Ca5Ga6O14

NASA Astrophysics Data System (ADS)

Tolkacheva, A. S.; Shkerin, S. N.; Kuzmin, A. V.; Plaksin, S. V.; Korzun, I. V.; Kochedykov, V. A.; Yaroslavtseva, T. V.; Vovkotrub, E. G.

2018-07-01

Calcium gallate Ca5Ga6O14 is synthesized by solid-phase means. Its melting point is 1325 ± 2°C. A phase transition of the second kind is observed in the temperature interval of 750-800°C. The temperature dependence of a thermal linear expansion coefficient within 200-900°C is given. Vibrational spectroscopy data confirm that Ca5Ga6O14 contains not only GaO4 tetrahedra but also GaO6 octahedra.

Efficacy of gaseous chlorine dioxide as a sanitizer for killing Salmonella, yeasts, and molds on blueberries, strawberries, and raspberries.

PubMed

Sy, Kaye V; McWatters, Kay H; Beuchat, Larry R

2005-06-01

Gaseous chlorine dioxide (ClO2) was tested for its effectiveness in killing Salmonella, yeasts, and molds on blueberries, strawberries, and red raspberries. An inoculum (100 microl, 6.0 to 6.8 log CFU/g of fruit) that contained five serotypes of Salmonella enterica was deposited on the skin, calyx tissue, or stem scar tissue of blueberries, skin or stem scar tissue of strawberries, and skin of red raspberries, dried for 2 h at 22 degrees C, then held for 20 h at 4 degrees C and 2 h at 22 degrees C before treatment. Sachets that contained reactant chemicals were formulated to release gaseous ClO2 at concentrations of 4.1, 6.2, and 8.0 mg/ liter of air within treatment times of 30, 60, and 120 min, respectively, at 23 +/- 1 degrees C. Lethality of ClO2 to Salmonella, yeasts, and molds was measured when fruits were in an atmosphere that contained 75 to 90% relative humidity. Treatment with 8.0 mg/liter of ClO2 significantly (alpha = 0.05) reduced the population of Salmonella on blueberries by 2.4 to 3.7 log CFU/g. Lethality was higher to cells in inoculum placed on the skin compared with the stem scar tissue. Populations of Salmonella on strawberries treated with 8.0 mg/liter of ClO2 were reduced by 3.8 to 4.4 log CFU/g; a significant reduction of 1.5 log CFU/g of raspberries was achieved. Treatment with 4.1 to 8.0 mg/liter of ClO2 caused reductions in populations of yeast and molds on blueberries, strawberries, and raspberries of 1.4 to 2.5, 1.4 to 4.2, and 2.6 to 3.0 log CFU/g, respectively. Treatment with 4.1 mg/liter of ClO2 did not markedly affect the sensory quality of fruits stored for up to 10 days at 8 degrees C. Results indicate that gaseous ClO2 has promise as a sanitizer for small fruits.

Single-crystal X-ray diffraction and NMR crystallography of a 1:1 cocrystal of di­thia­non and pyrimethanil

PubMed Central

Pöppler, Ann-Christin; Corlett, Emily K.; Pearce, Harriet; Seymour, Mark P.; Reid, Matthew; Montgomery, Mark G.

2017-01-01

A single-crystal X-ray diffraction structure of a 1:1 cocrystal of two fungicides, namely di­thia­non (DI) and pyrimethanil (PM), is reported [systematic name: 5,10-dioxo-5H,10H-naphtho­[2,3-b][1,4]dithiine-2,3-dicarbo­nitrile–4,6-dimethyl-N-phenyl­pyrimidin-2-amine (1/1), C14H4N2O2S2·C12H13N2]. Following an NMR crystallography approach, experimental solid-state magic angle spinning (MAS) NMR spectra are presented together with GIPAW (gauge-including projector augmented wave) calculations of NMR chemical shieldings. Specifically, experimental 1H and 13C chemical shifts are determined from two-dimensional 1H–13C MAS NMR correlation spectra recorded with short and longer contact times so as to probe one-bond C—H connectivities and longer-range C⋯H proximities, whereas H⋯H proximities are identified in a 1H double-quantum (DQ) MAS NMR spectrum. The performing of separate GIPAW calculations for the full periodic crystal structure and for isolated mol­ecules allows the determination of the change in chemical shift upon going from an isolated mol­ecule to the full crystal structure. For the 1H NMR chemical shifts, changes of 3.6 and 2.0 ppm correspond to inter­molecular N—H⋯O and C—H⋯O hydrogen bonding, while changes of −2.7 and −1.5 ppm are due to ring current effects associated with C—H⋯π inter­actions. Even though there is a close inter­molecular S⋯O distance of 3.10 Å, it is of note that the mol­ecule-to-crystal chemical shifts for the involved sulfur or oxygen nuclei are small. PMID:28257008