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Sample records for ligands synthesis spectral

  1. Synthesis, spectral and electrochemical studies of binuclear Ru(III) complexes containing dithiosemicarbazone ligand

    NASA Astrophysics Data System (ADS)

    Kanchana Devi, A.; Ramesh, R.

    2014-01-01

    Synthesis of several new octahedral binuclear ruthenium(III) complexes of the general composition [(EPh3)2(X)Ru-L-Ru(X)(EPh3)2] containing benzene dithiosemicarbazone ligands (where E = P or As; X = Cl or Br; L = binucleating ligands) is presented. All the complexes have been fully characterized by elemental analysis, FT-IR, UV-vis and EPR spectroscopy together with magnetic susceptibility measurements. IR study shows that the dithiosemicarbazone ligands behave as dianionic tridentate ligands coordinating through the oxygen atom of the deprotonated phenolic group, nitrogen atom of the azomethine group and thiolate sulphur. In DMF solution, all the complexes exhibit intense d-d transition and ligand-to-metal charge transfer (LMCT) transition in the visible region. The magnetic moment values of the complexes are in the range 1.78-1.82 BM, which reveals the presence of one unpaired electron on each metal ion. The EPR spectra of the liquid samples at LNT show the presence of three different 'g' values (gx ≠ gy ≠ gz) indicate a rhombic distortion around the ruthenium ion. All the complexes exhibit two quasi-reversible one electron oxidation responses (RuIII-RuIII/RuIII-RuIV; RuIII-RuIV/RuIV-RuIV) within the E1/2 range of 0.61-0.74 V and 0.93-0.98 V respectively, versus Ag/AgCl.

  2. Synthesis, spectral and electrochemical studies of binuclear Ru(III) complexes containing dithiosemicarbazone ligand.

    PubMed

    Kanchana Devi, A; Ramesh, R

    2014-01-01

    Synthesis of several new octahedral binuclear ruthenium(III) complexes of the general composition [(EPh3)2(X)Ru-L-Ru(X)(EPh3)2] containing benzene dithiosemicarbazone ligands (where E=P or As; X=Cl or Br; L=binucleating ligands) is presented. All the complexes have been fully characterized by elemental analysis, FT-IR, UV-vis and EPR spectroscopy together with magnetic susceptibility measurements. IR study shows that the dithiosemicarbazone ligands behave as dianionic tridentate ligands coordinating through the oxygen atom of the deprotonated phenolic group, nitrogen atom of the azomethine group and thiolate sulphur. In DMF solution, all the complexes exhibit intense d-d transition and ligand-to-metal charge transfer (LMCT) transition in the visible region. The magnetic moment values of the complexes are in the range 1.78-1.82 BM, which reveals the presence of one unpaired electron on each metal ion. The EPR spectra of the liquid samples at LNT show the presence of three different 'g' values (gx≠gy≠gz) indicate a rhombic distortion around the ruthenium ion. All the complexes exhibit two quasi-reversible one electron oxidation responses (Ru(III)-Ru(III)/Ru(III)-Ru(IV); Ru(III)-Ru(IV)/Ru(IV)-Ru(IV)) within the E1/2 range of 0.61-0.74 V and 0.93-0.98 V respectively, versus Ag/AgCl. PMID:23988528

  3. Synthesis, spectral, optical properties and theoretical calculations on schiff bases ligands containing o-tolidine

    NASA Astrophysics Data System (ADS)

    Arroudj, S.; Bouchouit, M.; Bouchouit, K.; Bouraiou, A.; Messaadia, L.; Kulyk, B.; Figa, V.; Bouacida, S.; Sofiani, Z.; Taboukhat, S.

    2016-06-01

    This paper explores the synthesis, structure characterization and optical properties of two new schiff bases. These compounds were obtained by condensation of o-tolidine with salicylaldehyde and cinnamaldehyde. The obtained ligands were characterized by UV, 1H and NMR. Their third-order NLO properties were measured using the third harmonic generation technique on thin films at 1064 nm. The electric dipole moment (μ), the polarizability (α) and the first hyperpolarizability (β) were calculated using the density functional B3LYP method with the lanl2dz basis set. For the results, the title compound shows nonzero β value revealing second order NLO behaviour.

  4. New metal complexes of N3 tridentate ligand: Synthesis, spectral studies and biological activity

    NASA Astrophysics Data System (ADS)

    Al-Hamdani, Abbas Ali Salih; Al Zoubi, Wail

    2015-02-01

    New tridentate ligand 3-amino-4-{1,5-dimethyl-3-[2-(5-methyl-1H-indol-3-yl)-ethylimino]-2phenyl-2,3-dihydro-1H-pyrazol-4-ylazo}-phenol L was synthesized from the reaction of 1,5-dimethyl-3-[2-(5-methyl-1H-indol-3-yl)-ethylimino]-2-phenyl-2,3-dihydro-1H-pyrazol-4-ylamine and 3.4-amino phenol. A complexes of these ligand [Ni(II)(L)(H2O)2 Cl]Cl, [pt(IV)(L)Cl3]Cl and [M(II)(L)Cl]Cl (M = Pd (II), Zn (II), Cd (II) and Hg (II) were synthesized. The complexes were characterized by spectroscopic methods and magnetic moment measurements, elemental analysis, metal content, Chloride containing and conductance. These studies revealed octahedral geometries for the Ni (II), pt (IV) complexes, square planar for Pd (II) complex and tetrahedral for the Zn (II), Cd(II) and Hg (II) complexes. The study of complexes formation via molar ratio and job method in DMF solution has been investigated and results were consistent to those found in the solid complexes with a ratio of (M:L) as (1:1). The thermodynamic parameters, such as ΔE*, ΔH*, ΔS* ΔG* and K are calculated from the TGA curve using Coats-Redfern method. Hyper Chem-8 program has been used to predict structural geometries of compounds in gas phase. The synthesized ligand and its metal complexes were screened for their biological activity against bacterial species, two Gram positive bacteria (Bacillus subtilis and Staphylococcus aureus) and two Gram negative bacteria (Escherichia coli and Pseudomonasaeruginosa).

  5. Synthesis and spectral studies of copper complexes using a N-octylated bis benzimidazole diamide ligand

    NASA Astrophysics Data System (ADS)

    Mohapatra, Subash Chandra; Mathur, Pavan

    2011-02-01

    Monomeric Cu(II) and Cu(I) complexes bound to a tetradentate bis-benzimidazole diamide ligand N,N'-bis(N-octyl benzimidazolyl-2yl)(methyl)pentane diamide (O-GBGA) have been isolated and characterized. X-Band EPR spectra of the copper(II) complexes in CH 2Cl 2 were recorded in a frozen solution as solvent at liquid nitrogen temperature. Solution spectra typically indicate a d ground state ( g|| > g⊥ > 2.0023) and show less than four nuclear hyperfine lines with broadening of g⊥ line in some cases, thus indicating distorted tetragonal geometry. One of the copper(II) complexes shows a five line N-SHF structure (16 ± 1 G) implying the binding of imine nitrogen of the benzimidazole to copper ion. α2 ranges from 0.57-0.97 indicating considerable amount of covalent character in Cu-L bond. Anodic shifts in E1/2 values indicate the retention of anion in the coordination sphere of Cu(II), E1/2 values becoming anodic in the order C 6H 5COO - < SCN - < Cl -. The fluorescence quantum yield of complexes was found to be lower than that of the ligand O-GBGA ( Φ = 0.029) and the relative fluorescence data reveals that fluorescence of such compounds could distinguish between small and large anions.

  6. Synthesis, spectral characterization, and antiproliferative studies of mixed ligand titanium complexes of adamantylamine.

    PubMed

    Kaushal, Raj; Kumar, Nitesh; Chaudhary, Ashun; Arora, Saroj; Awasthi, Pamita

    2014-01-01

    Titanium complexes have been synthesized by the reaction between titanium tetrachloride (TiCl4), respective bidentate ligand [4,4' -dimethoxy-2,2' -bipyridine (bpome), 6,6'-dimethyl-2,2'-bipyridine (dpme), 1,2-diaminocyclohexane (dach), 1,10-phenanthroline (phen), and benzoylacetone (bzac)], and adamantylamine (ada) in 1 : 2 : 2 molar ratios, respectively. The structure of synthesized complexes was confirmed using elemental analysis, FTIR, UV-visible, (1)H NMR, and mass spectrometry techniques. The nanocrystalline nature of complexes was confirmed by powder XRD study. The complexes were evaluated for cytotoxic potential in HeLa (cervical), C6 (glioma), and CHO (Chinese hamster ovarian) cell lines. The complex E was found to be more effective cytotoxic agent against HeLa cell line with an IC50 value of 4.06 µM. Furthermore, the effect of synthesized complexes was studied on different stages of the cell cycle in CHO cells. All complexes exhibited the dose dependent increase in cytotoxicity. The results have shown an increase in sub-G0 population with increase in concentration which is an indicative measure of apoptosis. PMID:24715822

  7. Synthesis, Spectral Characterization, and Antiproliferative Studies of Mixed Ligand Titanium Complexes of Adamantylamine

    PubMed Central

    Chaudhary, Ashun; Arora, Saroj; Awasthi, Pamita

    2014-01-01

    Titanium complexes have been synthesized by the reaction between titanium tetrachloride (TiCl4), respective bidentate ligand [4,4′ -dimethoxy-2,2′ -bipyridine (bpome), 6,6′-dimethyl-2,2′-bipyridine (dpme), 1,2-diaminocyclohexane (dach), 1,10-phenanthroline (phen), and benzoylacetone (bzac)], and adamantylamine (ada) in 1 : 2 : 2 molar ratios, respectively. The structure of synthesized complexes was confirmed using elemental analysis, FTIR, UV-visible, 1H NMR, and mass spectrometry techniques. The nanocrystalline nature of complexes was confirmed by powder XRD study. The complexes were evaluated for cytotoxic potential in HeLa (cervical), C6 (glioma), and CHO (Chinese hamster ovarian) cell lines. The complex E was found to be more effective cytotoxic agent against HeLa cell line with an IC50 value of 4.06 µM. Furthermore, the effect of synthesized complexes was studied on different stages of the cell cycle in CHO cells. All complexes exhibited the dose dependent increase in cytotoxicity. The results have shown an increase in sub-G0 population with increase in concentration which is an indicative measure of apoptosis. PMID:24715822

  8. Synthesis, spectral characterization, molecular modeling, thermal study and biological evaluation of transition metal complexes of a bidentate Schiff base ligand

    NASA Astrophysics Data System (ADS)

    Chandra, Sulekh; Bargujar, Savita; Nirwal, Rita; Qanungo, Kushal; Sharma, Saroj K.

    2013-09-01

    Complexes of copper(II) and nickel(II) of general composition M(L)2X2, have been synthesized [where L = 3-Bromoacetophenone thiosemicarbazone and X = CH3COO-, Cl- and NO3-]. All the complexes were characterized by elemental analysis, magnetic moments, IR, electronic and EPR spectral studies. The ligand behaved as bidentate and coordinated through sulfur of sbnd Cdbnd S group and nitrogen atoms of sbnd Cdbnd N group. The copper(II) and nickel(II) complexes were found to have magnetic moments 1.94-2.02 BM, 2.96-3.02 BM respectively which was corresponding to one and two unpaired electrons respectively. The molar conductance of the complexes in solution of DMSO lies in the range of 10-20 Ω-1 cm2 mol-1 indicating their non-electrolytic behavior. On the basis of EPR, electronic and infrared spectral studies, tetragonal geometry has been assigned for copper(II) complexes and an octahedral geometry for nickel(II) complexes. The values of Nephelauxetic parameter β lie in the range 0.19-0.37 which indicated the covalent character in metal ligand ‘σ' bond. Synthesized ligand and its copper(II) and nickel(II) complexes have also been screened against different bacterial and fungal species which suggested that complexes are more active than the ligands in antimicrobial activities.

  9. Synthesis of metal complexes involving Schiff base ligand with methylenedioxy moiety: Spectral, thermal, XRD and antimicrobial studies

    NASA Astrophysics Data System (ADS)

    Sundararajan, M. L.; Jeyakumar, T.; Anandakumaran, J.; Karpanai Selvan, B.

    2014-10-01

    Metal complexes of Zn(II), Cd(II), Ni(II), Cu(II), Fe(III), Co(II), Mn(II) Hg(II), and Ag(I) have been synthesized from Schiff base ligand, prepared by the condensation of 3,4-(methylenedioxy)aniline and 5-bromo salicylaldehyde. All the compounds have been characterized by using elemental analysis, molar conductance, FT-IR, UV-Vis, 1H NMR, 13C NMR, mass spectra, powder XRD and thermal analysis (TG/DTA) technique. The elemental analysis suggests the stoichiometry to be 1:1 (metal:ligand). The FT-IR, 1H NMR, 13C NMR and UV-Vis spectral data suggest that the ligand coordinate to the metal atom by imino nitrogen and phenolic oxygen as bidentate manner. Mass spectral data further support the molecular mass of the compounds and their structure. Powder XRD indicates the crystalline state and morphology of the ligand and its metal complexes. The thermal behaviors of the complexes prove the presence of lattice as well as coordinated water molecules in the complexes. Melting point supports the thermal stability of all the compounds. The in vitro antimicrobial effects of the synthesized compounds were tested against five bacterial and three fungal species by well diffusion method. Antioxidant activities have also been performed for all the compounds. Metal complexes show more biological activity than the Schiff base.

  10. Synthesis of metal complexes involving Schiff base ligand with methylenedioxy moiety: spectral, thermal, XRD and antimicrobial studies.

    PubMed

    Sundararajan, M L; Jeyakumar, T; Anandakumaran, J; Karpanai Selvan, B

    2014-10-15

    Metal complexes of Zn(II), Cd(II), Ni(II), Cu(II), Fe(III), Co(II), Mn(II) Hg(II), and Ag(I) have been synthesized from Schiff base ligand, prepared by the condensation of 3,4-(methylenedioxy)aniline and 5-bromo salicylaldehyde. All the compounds have been characterized by using elemental analysis, molar conductance, FT-IR, UV-Vis, (1)H NMR, (13)C NMR, mass spectra, powder XRD and thermal analysis (TG/DTA) technique. The elemental analysis suggests the stoichiometry to be 1:1 (metal:ligand). The FT-IR, (1)H NMR, (13)C NMR and UV-Vis spectral data suggest that the ligand coordinate to the metal atom by imino nitrogen and phenolic oxygen as bidentate manner. Mass spectral data further support the molecular mass of the compounds and their structure. Powder XRD indicates the crystalline state and morphology of the ligand and its metal complexes. The thermal behaviors of the complexes prove the presence of lattice as well as coordinated water molecules in the complexes. Melting point supports the thermal stability of all the compounds. The in vitro antimicrobial effects of the synthesized compounds were tested against five bacterial and three fungal species by well diffusion method. Antioxidant activities have also been performed for all the compounds. Metal complexes show more biological activity than the Schiff base. PMID:24820326

  11. Synthesis, NMR spectral and structural studies on mixed ligand complexes of Pd(II) dithiocarbamates: First structural report on palladium(II) dithiocarbamate with SCN-ligand

    NASA Astrophysics Data System (ADS)

    Prakasam, Balasubramaniam Arul; Lahtinen, Manu; Peuronen, Anssi; Muruganandham, Manickavachagam; Kolehmainen, Erkki; Haapaniemi, Esa; Sillanpää, Mika

    2016-03-01

    Three new mixed ligand complexes of palladium(II) dithiocarbamates; [Pd(4-dpmpzdtc)(PPh3)(SCN)] (1), [Pd(4-dpmpzdtc)(PPh3)Cl] (2) and [Pd(bzbudtc)(PPh3)Cl] (3), (where, 4-dpmpzdtc = 4-(diphenylmethyl)piperazinecarbodithioato anion, bzbudtc = N-benzyl-N-butyldithiocarbamato anion and PPh3 = triphenylphosphine) have been synthesized from their respective parent dithiocarbamates by ligand exchange reactions and characterized by IR and NMR (1H, 13C and 31P) spectroscopy. IR and NMR spectral data support the isobidentate coordination of the dithiocarbamate ligands in all complexes (1-3) in solid and in solution, respectively. Single crystal diffraction analysis of complexes 1-3 evidences that all three complexes are exhibiting distorted square planar geometry. The Pd-S distances in 1-3 vary in accordance with the differences in trans influences of PPh3, SCN- and Cl- and it is in the order of PPh3 > SCN- > and Cl-. Interchange of the anionic auxiliary ligand (SCN- to Cl-) induces asymmetry to the dithiocarbamate-metal bonds. Thioureide C-N bond distances are short in 1-3, supporting a contribution of thioureide form to the structures. The observed distortions in the square planar geometry for 1-3, are in the order of 1 > 2 > 3.

  12. Synthesis, spectral, thermal and antimicrobial studies of transition metal complexes of 14-membered tetraaza[N₄] macrocyclic ligand.

    PubMed

    Shankarwar, Sunil G; Nagolkar, Bhagwat B; Shelke, Vinod A; Chondhekar, Trimbak K

    2015-06-15

    A series of metal complexes of Mn(II), Co(II), Ni(II), Cu(II), have been synthesized with newly synthesized biologically active macrocyclic ligand. The ligand was synthesized by condensation of β-diketone 1-(4-chlorophenyl)-3-(2-hydroxyphenyl)propane-1,3-dione and o-phenylene diamine. All the complexes were characterized by elemental analysis, molar conductivity, magnetic susceptibility, thermal analysis, X-ray diffraction, IR, (1)H-NMR, UV-Vis spectroscopy and mass spectroscopy. From the analytical data, stoichiometry of the complexes was found to be 1:2 (metal:ligand). Thermal behavior (TG/DTA) and kinetic parameters suggest more ordered activated state in complex formation. All the complexes are of high spin type and six coordinated. On the basis of IR, electronic spectral studies and magnetic behavior, an octahedral geometry has been assigned to these complexes. The antibacterial and antifungal activities of the ligand and its metal complexes, has been screened in vitro against Staphylococcus aureus, Escherichia coli and Aspergillus niger, Trichoderma respectively. PMID:25775943

  13. Synthesis, spectral, thermal and antimicrobial studies of transition metal complexes of 14-membered tetraaza[N4] macrocyclic ligand

    NASA Astrophysics Data System (ADS)

    Shankarwar, Sunil G.; Nagolkar, Bhagwat B.; Shelke, Vinod A.; Chondhekar, Trimbak K.

    2015-06-01

    A series of metal complexes of Mn(II), Co(II), Ni(II), Cu(II), have been synthesized with newly synthesized biologically active macrocyclic ligand. The ligand was synthesized by condensation of β-diketone 1-(4-chlorophenyl)-3-(2-hydroxyphenyl)propane-1,3-dione and o-phenylene diamine. All the complexes were characterized by elemental analysis, molar conductivity, magnetic susceptibility, thermal analysis, X-ray diffraction, IR, 1H-NMR, UV-Vis spectroscopy and mass spectroscopy. From the analytical data, stoichiometry of the complexes was found to be 1:2 (metal:ligand). Thermal behavior (TG/DTA) and kinetic parameters suggest more ordered activated state in complex formation. All the complexes are of high spin type and six coordinated. On the basis of IR, electronic spectral studies and magnetic behavior, an octahedral geometry has been assigned to these complexes. The antibacterial and antifungal activities of the ligand and its metal complexes, has been screened in vitro against Staphylococcus aureus, Escherichia coli and Aspergillus niger, Trichoderma respectively.

  14. Synthesis and spectral studies on metal complexes of s-triazine based ligand and non linear optical properties

    NASA Astrophysics Data System (ADS)

    Shanmugakala, R.; Tharmaraj, P.; Sheela, C. D.

    2014-11-01

    A series of transition metal complexes of type [ML] and [ML2]Cl2 (where M = Cu(II), Ni(II), Co(II) have synthesized from 2-phenylamino-4,6-dichloro-s-triazine and 3,5-dimethyl pyrazole; their characteristics have been investigated by means of elemental analyses, magnetic susceptibility, molar conductance, IR, UV-Vis, Mass, NMR and ESR spectra. The electrochemical behavior of copper(II) complexes we have studied, by using cyclic voltammetry. The ESR spectra of copper(II) complexes are recorded at 300 K and 77 K and their salient features are appropriately reported. Spectral datas, we found, show that the ligand acts as a neutral tridentate, and coordinates through the triazine ring nitrogen and pyrazolyl ring nitrogen atoms to the metal ion. Evident from our findings, the metal(II) complexes of [ML] type exhibit square pyramidal geometry, and that of [ML2]Cl2 exhibit octahedral geometry. The in vitro antimicrobial activities of the ligand and its complexes are evaluated against Bacillus subtilis, Micrococcus luteus, Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus mutans, Escherichia coli, Enterobacter aerogenes, Klebsiella pneumoniae, Proteus vulgaris, Cryptococcus neoformans, Pseudomonas aeruginosa, Salmonella typhi, Serratia marcescens, Shigella flexneri, Vibrio cholera, Vibris parahaemolyticus, Aspergillus niger, Candida albicans and Penicillium oxalicum by well-diffusion method. The second harmonic generation efficiency of the ligand and its complexes are determined and compared with urea and KDP.

  15. Studies on some metal complexes of quinoxaline based unsymmetric ligand: Synthesis, spectral characterization, in vitro biological and molecular modeling studies.

    PubMed

    Dhanaraj, Chellaian Justin; Johnson, Jijo

    2016-08-01

    Mononuclear Co(II), Ni(II), Cu(II) and Zn(II) complexes of an unsymmetric Schiff base ligand, 3-(-(3-(-3,5-dichloro-2-hydroxybenzylideneamino)propylimino)methyl)quinoxalin-2(1H) -one (L) were synthesized and characterized by various analytical and spectral techniques. The molar conductance values of metal complexes indicate non-electrolytic behavior of the metal complexes. The Schiff base act as tetra dentate ONNO donor ligand in Co(II), Ni(II), Zn(II) complexes and tridentate NNO donor in Cu(II) complex. Thermal stabilities of the newly synthesized compounds were determined by thermal analysis. Crystallinity, average grain size and unit cell parameters were determined from powder X-ray diffraction study. Electrochemical behaviors of the compounds were examined by cyclic voltammetry technique. The Schiff base and its complexes have been screened for their in vitro antimicrobial activities against some bacterial and fungal strains by disc diffusion method. The interaction of the compounds with calf thymus DNA (CT DNA) has been investigated by electronic absorption spectral titration and viscosity measurement (hydrodynamic) methods. Furthermore, the pUC18 DNA cleavage activities of the complexes have been explored. The compounds were also subjected to in vitro antioxidant, anticancer activity screening, druglikeness and bioactivity predictions using Molinspiration software. Molecular docking studies of the present compounds were carried out against B-DNA dodecamer d(CGCGAATTCGCG)2 and vascular endothelial growth factor receptor (VEGFR-2) kinase. Quantum chemical calculations were done with DFT method to determine the optimum geometry of the ligand and its metal complexes. From the quantum chemical parameters, the reactivity parameters of the compounds were established. PMID:27236046

  16. Synthesis and spectral investigations of vanadium(IV/V) complexes derived from an ONS donor thiosemicarbazone ligand

    NASA Astrophysics Data System (ADS)

    Mangalam, Neema Ani; Kurup, M. R. Prathapachandra

    2009-01-01

    Four oxovanadium and one dioxovanadium complex with 2-hydroxyacetophenone N(4)-phenylthiosemicarbazone (H 2L) which are represented as [VOLphen]·2H 2O ( 1), [VOLbipy] ( 2), [VOLdmbipy] ( 3), [VOL] 2 ( 4) and [VO 2HL]·CH 3OH ( 5) have been synthesized and characterized by elemental analyses, electronic, infrared and EPR spectral techniques. In all the complexes 1- 4 the ligand coordinates through phenolic oxygen, azomethine nitrogen and thiolate sulfur. But in complex [VO 2HL]·CH 3OH, coordination takes place in thione form instead of thiolate sulfur. All the complexes except [VO 2HL]·CH 3OH are EPR active due to the presence of an unpaired electron. In frozen DMF at 77 K, all the oxovanadium(IV) complexes show axial anisotropy with two sets of eight line patterns.

  17. Synthesis, spectral and thermal studies of some transition metal mixed ligand complexes: Modeling of equilibrium composition and biological activity

    NASA Astrophysics Data System (ADS)

    Neelakantan, M. A.; Sundaram, M.; Nair, M. Sivasankaran

    2011-09-01

    Several mixed ligand Ni(II), Cu(II) and Zn(II) complexes of 2-amino-3-hydroxypyridine (AHP) and imidazoles viz., imidazole (him), benzimidazole (bim), histamine (hist) and L-histidine (his) have been synthesized and characterized by elemental and spectral (vibrational, electronic, 1H NMR and EPR) data as well as by magnetic moment values. On the basis of elemental analysis and molar conductance values, all the complexes can be formulated as [MAB]Cl except histidine complexes as MAB. Thermogravimetric studies reveal the presence of coordinated water molecules in most of the complexes. From the magnetic measurements and electronic spectral data, octahedral structure was proposed for Ni(II) and Cu(II)-AHP-his, tetrahedral for Cu(II)-AHP-him/bim/hist, but square planar for the Cu(II)-AHP complex. The g∥/ A∥ calculated supports tetrahedral environment around the Cu(II) in Cu(II)-AHP-him/bim/hist and distorted octahedral for Cu(II)-AHP-his complexes. The morphology of the reported metal complexes was investigated by scanning electron micrographs (SEM). The potentiometric study has been performed in aqueous solution at 37 °C and I = 0.15 mol dm -3 NaClO 4. MABH, MAB and MAB 2 species has been identified in the present systems. Proton dissociation constants of AHP and stability constants of metal complexes were determined using MINIQUAD-75. The most probable structure of the mixed ligand species is discussed based upon their stability constants. The in vitro biological activity of the complexes was tested against the Gram positive and Gram negative bacteria, fungus and yeast. The oxidative DNA cleavage studies of the complexes were performed using gel electrophoresis method. Cu(II) complexes have been found to promote DNA cleavage in presence of biological reductant such as ascorbate and oxidant like hydrogen peroxide.

  18. Synthesis, spectral characterization, DNA interaction, anticancer and molecular docking studies on some transition metal complexes with bidentate ligand.

    PubMed

    Dhanaraj, C Justin; Hassan, Israr Ul; Johnson, Jijo; Joseph, J; Joseyphus, R Selwin

    2016-09-01

    The ligand, N(2),N(3)-bis(3-nitrophenyl)quinoxaline-2.3-diamine was prepared by the condensation of quinoxaline-2.3(1,4H)-dione with 3-nitroaniline. It was treated with Co(II), Ni(II), Cu(II) and Zn(II) acetates to form the metal complexes. These were characterized by elemental analysis, molar conductance, magnetic moment, UV-Vis., IR, (1)H NMR, ESR and mass spectral data. Octahedral geometry has been assigned to Co(II), Ni(II) and Zn(II) complexes, whereas Cu(II) complex has distorted octahedral geometry. From the powder XRD data, crystallite size and unit cell parameters were calculated. The surface morphology of the synthesized compounds were determined using SEM analysis. The antimicrobial activity of the compounds against some bacterial species viz. Escherichiacoli, Klebsiella pneumoniae, Pseudomonas aeuruginosa and Staphylococcus aureus; also the fungal species, Aspergillus niger, and Candida albicans were done by disc diffusion method. DNA binding, cleavage and super oxide anion scavenging activities were also evaluated. The DNA binding activity of the compounds were identified using electronic absorption titrations and DNA cleavage was determined using gel electrophoresis. The anticancer activities of the compounds against HeLa cell line were determined using MTT assay. The highly potent compound among the five against HeLa cell line is subjected to molecular docking study against human papilloma virus receptor molecule and ATP binding site of telomerase. PMID:27367456

  19. Mixed-ligand copper(II) phenolate complexes: Synthesis, spectral characterization, phosphate-hydrolysis, antioxidant, DNA interaction and cytotoxic studies

    NASA Astrophysics Data System (ADS)

    Gurumoorthy, Perumal; Mahendiran, Dharmasivam; Prabhu, Durai; Arulvasu, Chinnasamy; Rahiman, Aziz Kalilur

    2015-01-01

    A series of phenol-based mixed-ligand copper(II) complexes of the type [CuL1-4(diimine)] (1-8), where L1-4 = N1,N2-bis(5-substituted-2-hydroxybenzylidene)-1,2-ethylene/phenylenediimine and diimine = 2,2‧-bipyridyl (bpy) or 1,10-phenanthroline (phen), have been isolated and fully characterized by analytical and spectral techniques. Electronic spectra of complexes suggest Cu(II) cation has a d9 electronic configuration, adopting distorted octahedral geometry with axial elongation, due to Jahn-Teller effect. Electrochemical studies of complexes evidenced one-electron irreversible reduction wave in the cathodic region. The observed rate constant (k) values for the hydrolysis of 4-nitrophenylphosphate (4-NPP) are in the range of 0.25-3.82 × 10-2 min-1. The obtained room temperature magnetic moment values (1.79-1.90 BM) lies within the range observed for octahedral copper(II) complexes. Antioxidant studies revealed that these complexes possess considerable radical scavenging potency against DPPH. The binding studies of complexes with calf thymus DNA (CT-DNA) revealed intercalation with minor-groove binding, and the complex 4 exhibits highest binding activity than the other complexes. The cleavage activity on supercoiled pBR322 DNA revealed the involvement of hydroxyl radical and singlet-oxygen as reactive oxygen species, and complexes encourage binding to minor-groove. Further, the cytotoxicity of complex 4 on human hepatocellular liver carcinoma HepG2 cell line implies the cell death through apoptosis.

  20. Synthesis, spectral, and thermal characterizations of Ni(II) and Cu(II) beta-diketone complexes with thenoyltrifluoroacetone ligand.

    PubMed

    Chen, Zhimin; Wu, Yiqun; Huang, Fuxin; Gu, Donghong; Gan, Fuxi

    2007-04-01

    Two kinds of nickel(II) and copper(II) beta-diketone complexes derived from thenoyltrifluoroacetone ligand with blue-violet light absorption were synthesized by reacting free ligand and different metal(II) ions in sodium methoxide solution. Their structures were postulated based on elemental analysis, ESI-MS, FT-IR spectra and UV-vis electronic absorption spectra. Smooth films on K9 glass substrates were prepared using the spin-coating method. Their solubility in organic solvents, absorption properties of thin film and thermal stability of these complexes were evaluated. PMID:16854616

  1. Synthesis, characterisation, spectral, thermal, XRD, molecular modelling and potential antibacterial study of metal complexes containing octadentate azodye ligands

    NASA Astrophysics Data System (ADS)

    Mahapatra, Bipin Bihari; Chaulia, Satyanarayan; Sarangi, Ashish Kumar; Dehury, Satyanarayan; Panda, Jnyanaranjan

    2015-05-01

    Twelve tetrametallic complexes of Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II) with two new octadentate azodye ligands, 4,4‧-bis(2‧,4‧-dihydroxy-5‧carboxyphenylazo) diphenylether (LH6) and 4,4‧-bis(2‧,4‧-dihydroxy-5‧-acylphenylazo) diphenylether (L‧H4) have been synthesised. The structural elucidation of the complexes was made basing upon analytical, conductance, magnetic susceptibility, IR, electronic spectra, ESR, NMR, ESI-MS, TG, DTG, DTA and X-ray diffraction (powder pattern) data. The cobalt (II) and nickel (II) complexes are found to be octahedral, copper (II) complexes are distorted octahedral and a tetrahedral stereochemistry has been suggested to zinc (II), cadmium (II) and mercury (II) complexes. The thermal analysis data provided the kinetic parameters as order of decomposition reaction, activation energy and frequency factor. The geometry of the ligands and their Co(II), Ni(II), Cu(II) and Zn(II) complexes were optimised and their physicochemical properties were calculated by using molecular modelling procedure. The ESI-MS determination supports the molecular formula and molecular weight of the ligands and the complexes. The Ni(II) complex is found to have a triclinic crystal system. The potential antibacterial study of the two ligands and eight metal complexes was made by cup-plate method against one gram positive and one gram negative bacteria. The results showed increase in the activity of some metal complexes as compare with azodye ligands.

  2. Synthesis of new oxamide-based ligand and its coordination behavior towards copper(II) ion: spectral and electrochemical studies.

    PubMed

    Krishnapriya, K R; Saravanakumar, D; Arunkumar, P; Kandaswamy, M

    2008-04-01

    A new ligand N,N'-bis{3-(2-formyl-4-methyl-phenol)-6-iminopropyl}oxamide (L) and its mono- and binuclear copper(II) complexes have been synthesized and characterized. The ligand shows absorption maxima at 249 and 360 with a weak transition at 455 nm. The ligand was found to be fluorescent and shows an emission maximum at 516 nm on excitation at 360 nm. The electronic spectra of the mono- and binuclear Cu(II) complexes exhibited a d-d transition in the region 520-560 nm characteristic of square planar geometry around Cu(II) ion. The ESR spectrum of the mononuclear complex showed four lines with nuclear hyperfine splitting. The binuclear complex showed a broad ESR spectrum with g=2.10 due to antiferromagnetic interaction between the two Cu(II) ions. The room-temperature magnetic moment values (micro(eff)) for the mono- and binuclear Cu(II) complexes are found to be 1.70 micro(B) and 1.45 micro(B), respectively. The electrochemical studies of the mononuclear Cu(II) complex showed a single irreversible one-electron wave at -0.70 V (E(pc)) and the binuclear Cu(II) complex showed two irreversible one-electron reduction waves at -0.75 V (E(pc)(1)) and -1.27 V (E(pc)(2)) in the cathodic region. PMID:17690008

  3. Synthesis of new oxamide-based ligand and its coordination behavior towards copper(II) ion: Spectral and electrochemical studies

    NASA Astrophysics Data System (ADS)

    Krishnapriya, K. R.; Saravanakumar, D.; Arunkumar, P.; Kandaswamy, M.

    2008-04-01

    A new ligand N, N'-bis{3-(2-formyl-4-methyl-phenol)-6-iminopropyl}oxamide ( L) and its mono- and binuclear copper(II) complexes have been synthesized and characterized. The ligand shows absorption maxima at 249 and 360 with a weak transition at 455 nm. The ligand was found to be fluorescent and shows an emission maximum at 516 nm on excitation at 360 nm. The electronic spectra of the mono- and binuclear Cu(II) complexes exhibited a d-d transition in the region 520-560 nm characteristic of square planar geometry around Cu(II) ion. The ESR spectrum of the mononuclear complex showed four lines with nuclear hyperfine splitting. The binuclear complex showed a broad ESR spectrum with g = 2.10 due to antiferromagnetic interaction between the two Cu(II) ions. The room-temperature magnetic moment values ( μeff) for the mono- and binuclear Cu(II) complexes are found to be 1.70 μB and 1.45 μB, respectively. The electrochemical studies of the mononuclear Cu(II) complex showed a single irreversible one-electron wave at -0.70 V ( Epc) and the binuclear Cu(II) complex showed two irreversible one-electron reduction waves at -0.75 V ( Epc1) and -1.27 V ( Epc2) in the cathodic region.

  4. Synthesis, thermal and spectral studies of first-row transition metal complexes with girard P reagent-based ligand

    NASA Astrophysics Data System (ADS)

    El-Ayaan, Usama; Kenawy, I. M.; El-Reash, Y. G. Abu

    2007-10-01

    A new series of first-row transition metal complexes with 1-acetylpyridinium chloride-4-benzoyl thiosemicarbazide (H 2GPBzIT) have been prepared and characterized by elemental analysis, spectroscopic and magnetic measurements. The proton-ligand ionization constants were determined potentiometrically using Irving-Rossotti technique. The stability constants of complexes were also calculated and were found in agreement with the seq uence of stability constants of Irving and Williams. Thermal stability and degradation kinetics have been measured using thermogravimetric analyzer. Kinetic parameters were obtained for each stage of thermal degradation of complexes using Coats-Redfern method.

  5. Novel amide-type ligand bearing bis-pyridine cores: Synthesis, spectral characterizations and X-ray structure analyses

    NASA Astrophysics Data System (ADS)

    Ke, Shaoyong

    2016-08-01

    The novel salicylamide-type ligand containing bis-pyridine moieties, i.e. 2-((6-chloropyridin-3-yl)methoxy)-N-(2-((6-chloropyridin-3-yl)methylthio)phenyl)benzamide, which has been successfully synthesized and characterized by typical spectroscopic techniques mainly including IR, 1H NMR and ESI-MS. The structure of target compound was further determined by single crystal X-ray diffraction method and which crystallized in the monoclinic system with space group P2(1)/c.

  6. Synthesis, thermal and spectral studies of first-row transition metal complexes with Girard-T reagent-based ligand

    NASA Astrophysics Data System (ADS)

    El-Ayaan, Usama; Kenawy, I. M.; Abu El-Reash, Y. G.

    2007-12-01

    The complexing behaviour of 1-acetyltrimethyl ammonium chloride-4-benzoyl thiosemicarbazide (H 2GTBzIT) towards the following first-row transition metal ions namely, Cr(III), Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) have been examined by elemental analysis, magnetic measurements, electronic, IR and 1H NMR. The proton-ligand ionization constants were determined potentiometrically using Irving-Rossotti technique. The stability constants of complexes were also calculated and were found in agreement with the sequence of stability constants of Irving and Williams. Thermal properties and decomposition kinetics of all complexes are investigated. The interpretation, mathematical analysis and evaluation of kinetic parameters ( E, A, Δ H, Δ S and Δ G) of all thermal decomposition stages have been evaluated using Coats-Redfern and Horowitz-Metzger equations.

  7. DNA binding, anti-inflammatory and analgesic evaluation of metal complexes of N/S/O donor ligands; Synthesis, spectral characterization

    NASA Astrophysics Data System (ADS)

    Kumar Naik, K. H.; Ashok, B.; Naik, Nagaraja; Mulla, Jameel Ahmed S.; Prakasha, Avinash

    2015-04-01

    Transition metal complexes containing tri-dentate NSN donor ligands i.e., 5-((1(aminomethyl)cyclohexyl)methyl)-1,3,4-thiadiazol-2-amine (AMTA) (2) and 5-(2-aminophenyl)-1,3,4-thiadiazol-2-amine (ATA) (4i-ii) have been synthesized. The newly synthesized ligands and their respective complexes were characterized by elemental analysis, molar conductance measurement and various spectral studies [infrared (IR), electronic, and NMR (for ligands only)]. Metal complexes are like [M(AMTA)2], [M(ATA)2] type, where M = Mn(II), Co(II) and Cu(II). The proposed geometries of the complexes are octahedral in nature. The synthesized ligands and their complexes were exhibits effective anti-inflammatory, analgesic and DNA binding activities. All the tested compounds exhibited significant analgesic activity, whereas the compound 4i, 4(ia) and 4(iib) is equipotent with Diclofenac sodium.

  8. Microwave Assisted Synthesis, Spectral and Antifungal Studies of 2-Phenyl-N,N′-bis(pyridin-4-ylcarbonyl)butanediamide Ligand and Its Metal Complexes

    PubMed Central

    Shiekh, Rayees Ahmad; Malik, Maqsood Ahmad; Al-Thabaiti, Shaeel Ahmed; Nabi, Arshid

    2014-01-01

    2-Phenyl-N,N′-bis(pyridin-4-ylcarbonyl)butanediamide ligand with a series of transition metal complexes has been synthesized via two routes: microwave irradiation and conventional heating method. Microwave irritation method happened to be the efficient and versatile route for the synthesis of these metal complexes. These complexes were found to have the general composition M(L)Cl2/M(L)(CH3COO)2 (where M = Cu(II), Co(II), Ni(II), and L = ligand). Different physical and spectroscopic techniques were used to investigate the structural features of the synthesized compounds, which supported an octahedral geometry for these complexes. In vitro antifungal activity of the ligand and its metal complexes revealed that the metal complexes are highly active compared to the standard drug. Metal complexes showed enhanced activity compared to the ligand, which is an important step towards the designing of antifungal drug candidates. PMID:24772018

  9. Synthesis, spectral, photolysis and electrochemical studies of mononuclear copper(II) complex with a new asymmetric tetradentate ligand: Application as copper nanoparticle precursor

    NASA Astrophysics Data System (ADS)

    Habibi, Mohammad Hossein; Mikhak, Maryam

    2012-10-01

    A copper(II) complex with asymmetric tetradentate Schiff base ligand, obtained by the single condensation of 1,2-diaminopropane with 2-hydroxy-5-methoxy benzaldehyde was prepared. The ligand and complex were characterized by their IR, UV-Vis, FT-IR, NMR spectra and CV. Crystal structures of the mononuclear copper complex have been obtained by X-ray diffraction studies which revealed to be distorted square planner coordination geometry. The spectral data confirm coordination of ligand to copper ion center. The redox properties of complex at different scan rates exhibit grossly similar features consisting of an electrochemically pseudo-reversible Cu(II)/Cu(I) reduction at ca. -0.97 V and pseudo-reversible Cu(I)/Cu(II) oxidation at ca. -0.81 V. The copper nanoparticles with average size of 73 nm were formed by thermal reduction of copper complex in the presence of triphenylphosphine.

  10. Synthesis, spectral characterization, molecular modeling and in vitro antibacterial activity of complexes designed from O2, NO and NO donor Schiff-base ligand

    NASA Astrophysics Data System (ADS)

    El-Gammal, Ola A.; Abu El-Reash, G.; Ahmed, S. F.

    2015-01-01

    A new chelating agent, N‧-(4-methoxybenzylidene)-2-oxo-2-(phenylamino)acetohydrazide (H2OMPH) and its complexes with Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Hg(II) and U(IV)O22+ ions have been prepared and characterized by conventional techniques. The spectral data indicated that the ligand coordinates as neutral bidentate with Cu(II), Mn(II), U(IV)O22+ and Hg(II), neutral tridentate with Ni(II), mononegative tridentate with Co(II) and binegative tetradentate with Zn(II) ions. On basis of magnetic and electronic spectral data an octahedral geometry for Mn(II), Co(II) and Ni(II) complexes and a square planar geometry for Cu(II) complex have been proposed and confirmed by applying geometry optimization and conformational analysis. The protonation constants of H2OMPH and the stepwise stability constants of its complexes are calculated at 298, 308 and 318 k as well as their thermodynamic parameters. Also, the Kinetic parameters (Ea, A, ΔH*, ΔS* and ΔG*) were determined for each thermal degradation stage of some complexes using Coats-Redfern and Horowitz-Metzger methods. Moreover, the ligand and some complexes were screened for in vitro antibacterial activity against Staphylococcus epidermalies (St. epid); Streptococcus pyagenies (Strp. py.) as Gram +ve bacteria and Escherichia coli (E. coli); Klebsiella spp. (kleb. spp.) as Gram -ve bacteria using inhibition zone diameter.

  11. Synthesis of mononuclear copper(II) complexes of acyclic Schiff's base ligands: Spectral, structural, electrochemical, antibacterial, DNA binding and cleavage activity

    NASA Astrophysics Data System (ADS)

    Jayamani, Arumugam; Thamilarasan, Vijayan; Sengottuvelan, Nallathambi; Manisankar, Paramasivam; Kang, Sung Kwon; Kim, Young-Inn; Ganesan, Vengatesan

    2014-03-01

    The mononuclear copper(II) complexes (1&2) of ligands L1 [N,N";-bis(2-hydroxy-5-methylbenzyl)-1,4-bis(3-iminopropyl)piperazine] or L2 [N,N";-bis(2-hydroxy-5-bromobenzyl)-1,4-bis(3-iminopropyl) piperazine] have been synthesized and characterised. The single crystal X-ray study had shown that ligands L1 and L2 crystallize in a monoclinic crystal system with P21/c space group. The mononuclear copper(II) complexes show one quasireversible cyclic voltammetric response near cathodic region (-0.77 to -0.85 V) in DMF assignable to the Cu(II)/Cu(I) couple. Binding interaction of the complexes with calf thymus DNA (CT DNA) investigated by absorption studies and fluorescence spectral studies show good binding affinity to CT DNA, which imply both the copper(II) complexes can strongly interact with DNA efficiently. The copper(II) complexes showed efficient oxidative cleavage of plasmid pBR322 DNA in the presence of 3-mercaptopropionic acid as reducing agent through a mechanistic pathway involving formation of singlet oxygen as the reactive species. The Schiff bases and their Cu(II) complexes have been screened for antibacterial activities which indicates that the complexes exhibited higher antimicrobial activity than the free ligands.

  12. Synthesis, crystal structure, spectral characterization and photoluminescence property of three Cd(II) complexes with a pyrazole based Schiff-base ligand

    NASA Astrophysics Data System (ADS)

    Mandal, Susmita; Saha, Rajat; Saha, Manan; Pradhan, Rajesh; Butcher, Ray J.; Saha, Nitis Chandra

    2016-04-01

    Substituted pyrazole containing Schiff-base ligand, 5-methyl-3-formylpyrazole-N-(2‧-methylphenoxy)methyleneimine, (MPzOA), afforded three new Cd(II) complexes, [Cd(MPzOA)Cl2]2.CH3OH (I), [Cd(MPzOA)2(H2O)2](ClO4)2 (II) and [Cd(MPzOA)(H2O)(NO3)2] (III). In the reported complex species the coordination number and geometry of Cd(II) vary. In complex I and II, Cd(II) adopts six and in (III) it adopts eight coordination modes, with prismatic, octahedral and distorted dodecahedral geometry, respectively. All the complexes are characterized by IR, 1H NMR, UV-Vis spectral parameters and X-ray analyses. The complexes have 1D, 2D and 3D supramolecular frameworks formed by non-covalent interactions, like hydrogen bonding, π … π stacking, C-H … π interactions.

  13. Ruthenium(II) bipyridine complexes bearing quinoline-azoimine (NN‧N″) tridentate ligands: Synthesis, spectral characterization, electrochemical properties and single-crystal X-ray structure analysis

    NASA Astrophysics Data System (ADS)

    Al-Noaimi, Mousa; Abdel-Rahman, Obadah S.; Fasfous, Ismail I.; El-khateeb, Mohammad; Awwadi, Firas F.; Warad, Ismail

    Four octahedral ruthenium(II) azoimine-quinoline complexes having the general molecular formula [RuII(Lsbnd Y)(bpy)Cl](PF6) {Lsbnd Y = YC6H4Ndbnd NC(COCH3)dbnd NC9H6N, Y = H (1), CH3 (2), Br (3), NO2 (4) and bpy = 2,2‧-bipyrdine} were synthesized. The azoimine-quinoline based ligands behave as NN‧N″ tridentate donors and coordinated to ruthenium via azo-N‧, imine-N‧ and quinolone-N″ nitrogen atoms. The composition of the complexes has been established by elemental analysis, spectral methods (FT-IR, electronic, 1H NMR, UV/Vis and electrochemical (cyclic voltammetry) techniques. The crystal structure of complex 1 is reported. The Ru(II) oxidation state is greatly stabilized by the novel tridentate ligands, showing Ru(III/II) couples ranging from 0.93-1.27 V vs. Cp2Fe/Cp2Fe+. The absorption spectrum of 1 in dichloromethane was modeled by time-dependent density functional theory (TD-DFT).

  14. Synthesis, spectral characterization, catalytic and antibacterial studies of new Ru(III) Schiff base complexes containing chloride/bromide and triphenylphosphine/arsine as co-ligands

    NASA Astrophysics Data System (ADS)

    Arunachalam, S.; Padma Priya, N.; Jayabalakrishnan, C.; Chinnusamy, V.

    2009-10-01

    A new Ru(III) Schiff base complexes of the type [RuX(EPh 3)L] (X = Cl/Br; E = P/As; L = dianion of the Schiff bases were derived by the condensation of 1,4-diformylbenzene with o-aminobenzoic acid/ o-aminophenol/ o-aminothiophenol in the 1:2 stoichiometric ratio) have been synthesized from the reactions of [RuX 3(EPh 3) 3] with appropriate Schiff base ligands in benzene in the 2:1 stoichiometric ratio. The new complexes have been characterized by analytical, spectral (IR, electronic, 1H, 13C NMR and ESR), magnetic moment and electrochemical studies. An octahedral structure has been tentatively proposed for all these new complexes. All the new complexes have been found to be better catalyst for the oxidation of alcohols using molecular oxygen as co-oxidant at ambient temperature and aryl-aryl coupling reactions. These complexes were also subjected to antibacterial activity studies against Escherichia coli, Aeromonas hydrophilla and Salmonella typhi.

  15. Mono- and binuclear copper(II) complexes of new hydrazone ligands derived from 4,6-diacetylresorcinol: Synthesis, spectral studies and antimicrobial activity

    NASA Astrophysics Data System (ADS)

    Shebl, Magdy; El-ghamry, Mosad A.; Khalil, Saied M. E.; Kishk, Mona A. A.

    Two new hydrazone ligands, H2L1 and H2L2, were synthesized by the condensation of 4,6-diacetylresorcinol with 3-hydrazino-5,6-diphenyl-1,2,4-triazine and isatin monohydrazone, respectively. The structures of the ligands were elucidated by elemental analyses, IR, 1H NMR, electronic and mass spectra. Reactions of the ligands with several copper(II) salts, including AcO-, NO3-, SO42-, Cl- and Br- afforded mono- and binuclear metal complexes. Also, the ligands were allowed to react with Cu(II) ion in the presence of a secondary ligand (L‧) [N,O-donor; 8-hydroxyquinoline, N,N-donor; 1,10-phenanthroline or O,O-donor; benzoylacetone]. Characterization and structure elucidation of the prepared complexes were achieved by elemental and thermal analyses, IR, electronic, mass and ESR spectra as well as conductivity and magnetic susceptibility measurements. The ESR spin Hamiltonian parameters of some complexes were calculated. The spectroscopic data showed that the H2L1 ligand acts as a neutral or monobasic tridentate ligand while the H2L2 ligand acts as a bis(monobasic tridentate) ligand. The coordination sites with the copper(II) ion are phenolic oxygen, azomethine nitrogen and triazinic nitrogen (H2L1 ligand) or isatinic oxygen (H2L2 ligand). The metal complexes exhibited octahedral and square planar geometrical arrangements depending on the nature of the anion. The ligands and some metal complexes showed antimicrobial activity.

  16. Binary and ternary copper(II) complexes of a tridentate ONS ligand derived from 2-aminochromone-3 carboxaldehyde and thiosemicarbazide: Synthesis, spectral studies and antimicrobial activity

    NASA Astrophysics Data System (ADS)

    Shebl, Magdy; Ibrahim, M. A.; Khalil, Saied M. E.; Stefan, S. L.; Habib, H.

    2013-11-01

    A tridentate ONS donor ligand, HL, was synthesized by the condensation of 2-aminochromone-3-carboxaldehyde with thiosemicarbazide. The structure of the ligand was elucidated by elemental analyses, IR, 1H and 13C NMR, electronic and mass spectra. Reaction of the ligand with several copper(II) salts, including AcO-, NO3-, SO42-, Cl-, Br- and ClO4- afforded different metal complexes that reflect the non-coordinating or weakly coordinating power of the ClO4- and Br- anions as compared to the strongly coordinating power of AcO-, SO42-, Cl- and NO3- anions. Also, the ligand was allowed to react with Cu(II) ion in the presence of a secondary ligand (L‧) [N,O-donor; 8-hydroxyquinoline or N,N-donor; 1,10-phenanthroline]. Characterization and structure elucidation of the prepared complexes were achieved by elemental and thermal analyses, IR, electronic, mass and EPR spectra as well as conductivity and magnetic susceptibility measurements. The EPR spin Hamiltonian parameters of some complexes were calculated. The metal complexes exhibited octahedral and square planar geometrical arrangements depending on the nature of the anion. The ligand and most of its metal complexes showed antibacterial activity towards Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis), Gram-negative bacteria (Salmonella typhimurium and Escherichia coli), yeast (Candida albicans) and fungus (Aspergillus fumigatus).

  17. Synthesis, structure and spectral properties of O,N,N coordinating ligands and their neutral Zn(ii) complexes: a combined experimental and theoretical study.

    PubMed

    Hens, Amar; Mondal, Pallab; Rajak, Kajal Krishna

    2013-10-01

    Mononuclear Zn(ii) complexes with the general formula [Zn(L)2] have been synthesized in good yields by reacting Zn(OAc)2 with HL in a ratio of 1 : 2 in methanol solvent. Here L is the deprotonated form of 6-[(quinolin-8-ylamino)methylene]cyclohexa-2,4-dienone (HL(1)), 4-chloro-6-[(quinolin-8-ylamino)methylene]cyclohexa-2,4-dienone (HL(2)), 4-methyl-6-[(quinolin-8-ylamino)methylene]cyclohexa-2,4-dienone (HL(3)), 2,4-dimethyl-6-[(quinolin-8-ylamino) methylene]cyclohexa-2,4-dienone (HL(4)), 2-methoxy-6-[(quinolin-8-ylamino) methylene]cyclohexa-2,4-dienone (HL(5)). The electronic structures and photophysical properties of the ligands were calculated by DFT and TDDFT methods. The X-ray structure of one complex is reported. The ligands have a strong binding ability [(0.75-15.37) × 10(4)] and ratiometric response to Zn(2+) ions. With the addition of Zn(2+) ions to the ligands in THF solution a sharp color change is observed visually, and as well a significant enhancement of the fluorescence intensity and the quantum yield for this series occurs. The introduction of other metal ions having biological and environmental effects results in either unaltered or quenched emission intensity. However we observed the sensing property of the ligands strongly depends on the substituent at the ortho position of the phenol group. DFT calculation reveals that the ICT process take place from the salicylaldehyde (donor moiety) to quinoline (acceptor moiety) which is responsible for the enhancement of the fluorescence intensity of ligands after complexation. PMID:23995072

  18. Tetra- and hexadentate Schiff base ligands and their Ni(II), Cu(II) and Zn(II) complexes. Synthesis, spectral, magnetic and thermal studies.

    PubMed

    Ismail, Tarek M A; Saleh, Akila A; El Ghamry, Mosad A

    2012-02-01

    Tetradentate N(2)O(2), N(4) Schiff bases, 1,2-bis(4-oxopent-2-ylideneamino) benzene (BOAB), 1-(4-oxopent-2-ylideneamino-2-[(2-hydroxyphenyl)ethylideneamino] benzene (OAHAB), 7,16-bis(4-chlorobenzylidene)-6,8,15,17-tetra-methyl-7,16-dihydro -5,9,14,18-tetraza-dibenzo[a,h] cyclo tetradecene (BCBDCT), 7,16-bis(2-hydroxy-benzylidene)-6,8,15,17-tetramethyl-7,16-dihydro-5,9,14,18-tetraza-dibenzo [a,h] cyclo tetradecene (BHBDCT) and hexadentate N(4)O(2) Schiff bases, 2,4-bis {2-[1-(2-hydroxyphenyl) ethylideneamino] phenylimino}-3-(2-hydroxybenzylidene) pentane (BHAPHP), 2,4-bis {2-[1-(2-hydroxyphenyl) ethylideneamino] phenylimino}-3-(4-chlorobenzylidene) pentane (BHAPCP) were prepared and characterized by elemental analysis, IR, UV-Vis, (1)H NMR and mass spectra. The solid complexes of the prepared Schiff base ligands with Ni(II), Cu(II) and Zn(II) ions were isolated and characterized by elemental and thermal analyses, IR, electronic and ESR spectra as well as conductance and magnetic susceptibility measurements. The results showed that most complexes have octahedral geometry but few can attain the tetrahedral arrangement. The TG analyses suggest high stability for most complexes followed by thermal decomposition in different steps. The kinetic and thermodynamic parameters for decomposition steps in Cu(II) complexes thermograms have been calculated. PMID:22070996

  19. Tetra- and hexadentate Schiff base ligands and their Ni(II), Cu(II) and Zn(II) complexes. Synthesis, spectral, magnetic and thermal studies

    NASA Astrophysics Data System (ADS)

    Ismail, Tarek M. A.; Saleh, Akila A.; Ghamry, Mosad A. El

    2012-02-01

    Tetradentate N 2O 2, N 4 Schiff bases, 1,2-bis(4-oxopent-2-ylideneamino) benzene (BOAB), 1-(4-oxopent-2-ylideneamino-2-[(2-hydroxyphenyl)ethylideneamino] benzene (OAHAB), 7,16-bis(4-chlorobenzylidene)-6,8,15,17-tetra-methyl-7,16-dihydro -5,9,14,18-tetraza-dibenzo[a,h] cyclo tetradecene (BCBDCT), 7,16-bis(2-hydroxy-benzylidene)-6,8,15,17-tetramethyl-7,16-dihydro-5,9,14,18-tetraza-dibenzo [a,h] cyclo tetradecene (BHBDCT) and hexadentate N 4O 2 Schiff bases, 2,4-bis {2-[1-(2-hydroxyphenyl) ethylideneamino] phenylimino}-3-(2-hydroxybenzylidene) pentane (BHAPHP), 2,4-bis {2-[1-(2-hydroxyphenyl) ethylideneamino] phenylimino}-3-(4-chlorobenzylidene) pentane (BHAPCP) were prepared and characterized by elemental analysis, IR, UV-Vis, 1H NMR and mass spectra. The solid complexes of the prepared Schiff base ligands with Ni(II), Cu(II) and Zn(II) ions were isolated and characterized by elemental and thermal analyses, IR, electronic and ESR spectra as well as conductance and magnetic susceptibility measurements. The results showed that most complexes have octahedral geometry but few can attain the tetrahedral arrangement. The TG analyses suggest high stability for most complexes followed by thermal decomposition in different steps. The kinetic and thermodynamic parameters for decomposition steps in Cu(II) complexes thermograms have been calculated.

  20. Synthesis, spectral, catalytic and antimicrobial studies of PPh 3/AsPh 3 complexes of Ru(II) with dibasic tridentate O, N, S donor ligands

    NASA Astrophysics Data System (ADS)

    Balasubramanian, K. P.; Karvembu, R.; Prabhakaran, R.; Chinnusamy, V.; Natarajan, K.

    2007-09-01

    Complexes of the type [Ru(CO)(EPh 3)(B)(L)] (E = P or As; B = PPh 3, AsPh 3, py or pip; L = dianion of the Schiff bases derived from thiosemicarbazone with acetoacetanilide, acetoacet- o-toluidide and o-chloro acetoacetanilide) have been synthesized from the reactions of equimolar amounts of [RuHCl(CO)(EPh 3) 2(B)] and Schiff bases in benzene. The new complexes have been characterized by analytical and spectral (IR, electronic, NMR) data. The arrangement of PPh 3 groups around ruthenium metal was determined from 31P NMR spectra. An octahedral structure has been assigned for all the new complexes. All the complexes exhibited catalytic activity for the oxidation of benzyl alcohol and cyclohexanol in presence of N-methylmorpholine- N-oxide as co-oxidant. The complexes also exhibited antibacterial activity against E. coli, Aeromonas hydrophilla and Salmonella typhi. The activity was compared with standard streptomycin.

  1. Synthesis, crystal structure, spectral studies, and catechol oxidase activity of trigonal bipyramidal Cu(II) complexes derived from a tetradentate diamide bisbenzimidazole ligand.

    PubMed

    Gupta, M; Mathur, P; Butcher, R J

    2001-02-26

    A new benzimidazole-based diamide ligand-N,N'-bis(glycine-2- benzimidazolyl)hexanediamide (GBHA)-has been synthesized and utilized to prepare Cu(II) complexes of general composition [Cu(GBHA)X]X, where X is an exogenous anionic ligand (X = Cl(-), NO(3)(-), SCN(-)). The X-ray structure of one of the complexes, [Cu(GBHA)Cl]Cl.H(2)O.CH(3)OH, has been obtained. The compound crystallizes in the monoclinic space group C2/c with unit cell dimensions a = 26.464(3) A, b = 10.2210(8) A, c = 20.444(2) A, alpha = 90 degrees, beta = 106.554(7) degrees, gamma = 90 degrees, V= 5300.7(9) A(3), and Z = 8. To the best of our knowledge, the [Cu(GBHA)Cl]Cl.H(2)O.CH(3)OH complex is the first structurally characterized mononuclear trigonal bipyramidal copper(II) bisbenzimidazole diamide complex having coordinated amide carbonyl oxygen. The coordination geometry around the Cu(II) ion is distorted trigonal bipyramidal (tau = 0.59). Two carbonyl oxygen atoms and a chlorine atom form the equatorial plane, while the two benzimidazole imine nitrogen atoms occupy the axial positions. The geometry of the Cu(II) center in the solid state is not preserved in DMSO solution, changing to square pyramidal, as suggested by the low-temperature EPR data g( parallel) > g( perpendicular) > 2.0023. All the complexes display a quasi-reversible redox wave due to the Cu(II)/Cu(I) reduction process. E(1/2) values shift anodically from Cl(-) < NO(3)(-) < SCN(-), indicating that the bound Cl(-) ion stabilizes the Cu(II) ion while the N-bonded SCN(-) ion destabilizes the Cu(II) state in the complex. When calculated against NHE, the redox potentials turn out to be quite positive as compared to other copper(II) benzimidazole bound complexes (Nakao, Y.; Onoda, M.; Sakurai, T.; Nakahara, A.; Kinoshita, L.; Ooi, S. Inorg. Chim. Acta 1988, 151, 55. Addison, A. W.; Hendricks, H. M. J.; Reedijk, J.; Thompson, L. K. Inorg. Chem. 1981, 20 (1), 103. Sivagnanam, U.; Palaniandavar, M. J. Chem. Soc., Dalton Trans. 1994, 2277

  2. Novel mixed ligand complexes of bioactive Schiff base (E)-4-(phenyl (phenylimino) methyl) benzene-1,3-diol and 2-aminophenol/2-aminobenzoic acid: Synthesis, spectral characterization, antimicrobial and nuclease studies

    NASA Astrophysics Data System (ADS)

    Subbaraj, P.; Ramu, A.; Raman, N.; Dharmaraja, J.

    2014-01-01

    A novel bidentate Schiff base ligand has been synthesized using 2,4-dihydroxybenzophenone and aniline. Its mixed ligand complexes of MAB type [M = Mn(II), Co(II), Ni(II), Cu(II) and Zn(II); HA = Schiff base and B = 2-aminophenol/2-aminobenzoic acid] have been synthesized and characterized on the basis of spectral data UV-Vis, IR, 1H NMR, FAB-Mass, EPR, SEM and magnetic studies. All the complexes were soluble in DMF and DMSO. Elemental analysis and molar conductance values indicate that the complexes are non-electrolytes. HA binds with M(II) ions through azomethine and deprotonated phenolic group and B binds through the primary amine group and deprotonated phenolic/carboxylic groups. Using FAB-Mass the cleavage pattern of the ligand (HA) has been established. All the complexes adopt octahedral geometry around the metal ions. It has been confirmed with the help of UV-Vis, IR, 1H NMR and FAB-Mass spectral data. DNA binding activities of the complexes 1d and 2d are studied by UV-Vis spectroscopy and cleavage studies of Schiff base ligand and its complexes 1d and 2d have been by agarose gel electrophoresis method. In vitro biological activities of the free ligand (HA) and their metal complexes (1a-1e and 2a-2e) were screened against few bacteria, Escherichia coli, Staphylococcus saphyphiticus, Staphylococcus aureus, Pseudomonas aeruginosa and fungi Aspergillus niger, Enterobacter species, Candida albicans by well diffusion technique.

  3. Glyconanomaterials: Synthesis, Characterization, and Ligand Presentation

    PubMed Central

    Wang, Xin

    2010-01-01

    Glyconanomaterials, nanomaterials carrying surface-tethered carbohydrate ligands, have emerged and demonstrated increasing potential in biomedical imaging, therapeutics, and diagnostics. These materials combine the unique properties of nanometer-scale objects with the ability to present multiple copies of carbohydrate ligands, greatly enhancing the weak affinity of individual ligands to their binding partners. Critical to the performance of glyconanomaterials is the proper display of carbohydrate ligands, taking into consideration of the coupling chemistry, the type and length of the spacer linkage, and the ligand density. This article provides an overview of the coupling chemistry for attaching carbohydrate ligands to nanomaterials, and discusses the need for thorough characterization of glyconanomaterials, especially quantitative analyses of the ligand density and binding affinities. Using glyconanoparticles synthesized by a versatile photocoupling chemistry, methods for determining the ligand density by colorimetry and the binding affinity with lectins by a fluorescence competition assay are determined. The results show that the multivalent presentation of carbohydrate ligands significantly enhances the binding affinity by several orders of magnitude in comparison to the free ligands in solution. The effect is sizeable even at low surface ligand density. The type and length of the spacer linkage also affect the binding affinity, with the longer linkage promoting the association of bound ligands with the corresponding lectins. PMID:20301131

  4. Synthesis, magnetism and spectral studies of six defective dicubane tetranuclear {M4O6} (M = Ni(II), Co(II), Zn(II)) and three trinuclear Cd(II) complexes with polydentate Schiff base ligands.

    PubMed

    Jiang, Lin; Zhang, Dong-Yan; Suo, Jing-Jing; Gu, Wen; Tian, Jin-Lei; Liu, Xin; Yan, Shi-Ping

    2016-06-21

    A series of Ni(II), Co(II), Zn(II) and Cd(II) complexes with polytopic Schiff base ligands have been synthesized. The single-crystal X-ray crystallography results show that tetranuclear complexes have common face-shared defective dicubane cores, whereas trinuclear Cd(II) complexes are almost linear entities. Synthesis methods (solvent evaporation and hydrothermal synthesis), reaction conditions (pH, solvents and dosage) and coligands (azide, methanol, chloride and acetate) play vital roles in determining the final structure of the complexes and therefore their magnetic properties. In complexes , the terminal and central M(2+) ions are connected through mixed bridges, μ-phenoxido/μ1,1,1-X and μ-Oalphatic/μ1,1,1-X, while central two M(2+) ions are linked by double bridges, μ1,1,1-X (X = azido and methoxido groups for and respectively). For complex , two central Ni(II) ions are connected through two μ1,1,1-N3(-) which is relatively less reported. For complexes , there are two kinds of Cd(II), the centre Cd(II) ions are eight-coordinated with triangle dodecahedral geometries, while the two side Cd(II) ions are six-coordinated with trigonal prism geometries using chlorides or acetates as terminal ligands. Magnetic susceptibility measurements (χM) for compounds have been performed, and they reveal predominant ferromagnetic exchange interactions in Co(II) and Ni(II) tetramers. The photoluminescence studies show that the Zn(II) complex and three Cd(II) complexes have strong fluorescence, and the lifetimes are measured to be in the 10(2) nanosecond timescale. PMID:27230103

  5. Synthesis and Photophysical Studies of Iridium Complexes Having Different Ligands

    NASA Astrophysics Data System (ADS)

    Rho, Hyeon Hee; Park, Gui Youn; Ha, Yunkyoung; Kim, Young Sik

    2006-01-01

    The synthesis and photophysical study of efficient phosphorescent iridium(III) complexes having two different (C∧N) ligands are reported. In order to improve the luminescence efficiency by avoiding triplet-triplet (T-T) annihilation, the iridium complexes, Ir(ppy)2(piq) and Ir(ppy)2(piq-F), are designed and prepared where ppy, piq and piq-F represent 2-phenylpyridine, 1-(phenyl)isoquinoline and 2-(4'-fluorophenyl)isoquinoline, respectively. Two ppy ligands and a piq derivative act as a source of energy supply and a piq derivative acts as a chromophore. Since Ir(ppy)3, Ir(piq)3 and Ir(piq-F)3 can be placed in the metal-to-ligand charge transfer (MLCT) excited state, they absorb light effectively. When Ir(ppy)2(piq-F) is placed in excited state, the excitation energy is neither quenched nor deactivated but quickly intramolecular transferred from two ppy ligands to one luminescent piq-F ligand. This can occure because the triplet energy level of ppy is higher than that of piq-F and light is emitted from piq-F ligand in the end. Thus, Ir(ppy)2(piq-F) shows strong photoluminescence originated from piq-F ligand because piq-F ligand is known to have a shorter lifetime than that of ppy ligand. To analyze luminescent mechanism, we calculated these complexes having two different ligand sets theoretically by using computational method.

  6. Synthesis, spectral and magnetic studies of mono- and bi-nuclear metal complexes of a new bis(tridentate NO2) Schiff base ligand derived from 4,6-diacetylresorcinol and ethanolamine

    NASA Astrophysics Data System (ADS)

    Shebl, Magdy

    2009-07-01

    A new bis(tridentate NO2) Schiff base ligand, H4L, was prepared by the reaction of the bifunctional carbonyl compound; 4,6-diacetylresorcinol (DAR) with ethanolamine. The ligand reacted with iron(III), cobalt(II), nickel(II), copper(II), zinc(II), cadmium(II), cerium(III) and uranyl(VI) ions, in absence and in presence of LiOH, to yield mono- and bi-nuclear complexes with different coordinating sites. The ligand and its metal complexes were characterized by elemental analyses, IR, 1H NMR, electronic, ESR and mass spectra, conductivity and magnetic susceptibility measurements as well as thermal analyses. In absence of LiOH, mononuclear complexes (2, 3 and 5-9) as well as binuclear complexes (1 and 4) were obtained. In mononuclear complexes, the ligand acted as a neutral, mono- and di-basic/bi- and tetra-dentate ligand while in binuclear complexes (1 and 4), the ligand acted as a bis(mono- or di-basic/tridentate) ligand. On the other hand, in presence of LiOH, only binuclear complexes (10-15) were obtained in which the ligand acted as a bis(dibasic tridentate) ligand. The metal complexes exhibited different geometrical arrangements such as octahedral, tetrahedral, square planar, square pyramidal and pentagonal bipyramidal arrangements.

  7. Recent advances in the synthesis of endocannabinoid related ligands.

    PubMed

    Razdan, R K; Mahadevan, A

    2002-12-31

    The chemical strategies used for the synthesis of various ligands related to the endocannabinoid system namely anandamide (AEA), 2-arachidonylglycerol (2-Ara-Gl), CB1/(vanilloid receptors) VR1, anandamide membrane transporter (AMT) and fatty acid amide hydrolase (FAAH) are described in this review. In general, the chemical synthesis of analogs with changes in the head group of AEA was quite straightforward involving the conversion of an acid to an amide or an ester. Analogs which had modifications in the end pentyl chain were more difficult to synthesize and required multistep synthetic sequences to prepare the target compounds. A facile total synthesis of 2-Ara-Gl was reported and an HPLC procedure for its identification and quantification was developed, but because of the instability of 2-Ara-Gl another synthesis was developed so that it can be stored as the more stable phenylboronate ester. Similarly the chemical synthesis of various ligands in the remaining areas of CB1/VR1, AMT and FAAH are described. A summary of the present state of knowledge about the SAR in each area is presented to help in the design and synthesis of novel ligands for the future. PMID:12505687

  8. Synthesis and Characterization of a New TRIPHOS Ligand Derivative and the Corresponding Pd(II) Complexes

    SciTech Connect

    Miller, Deanna L.; Boro, Brian J.; Grubel, Katarzyna; Helm, Monte L.; Appel, Aaron M.

    2015-12-01

    The synthesis of the new bis(2-(diphenylphosphino)ethyl)methylhydroxyphosphine tridentate phosphine ligand, LCH2OH/Ph, is reported. The ligand reacts with [Pd(Cl)2(PhCN)2 to form [Pd(LCH2OH/Ph)Cl]Cl. Exchange of the chloride ions for triflate (OTf–) using AgOTf yielded pure [Pd(LCH2OH/Ph)OTf]OTf. In addition to spectral characterization the free ligand, LCH2OH/Ph, and Pd(II) complex, [Pd(LCH2OH/Ph)OTf]OTf, are structurally characterized. This research was supported by the US Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Biosciences, and Geosciences. Pacific Northwest National Laboratory is a multiprogram national laboratory operated by Battelle for DOE.

  9. Ultraviolet spectral synthesis of HD 72660

    NASA Astrophysics Data System (ADS)

    Golriz, S. S.; Landstreet, J. D.

    2016-03-01

    The study of chemical abundances in stellar atmosphere provides a useful tool to investigate the formation and evolution history of stars. The optical wavelength range has been used almost exclusively in the past to determine the elemental abundance in A-type stars. We use high-resolution, high signal-to-noise ultraviolet spectra obtained from the STIS/NUV-MAMA instrument on board Hubble Space Telescope. The spectra available cover the wavelength ranges 1630 Å-1901 Å and 2130 Å-2887 Å. The main challenge to carrying out abundance analysis in the ultraviolet is the extreme level of line blending. Abundance analysis using single isolated spectral lines is almost completely impossible; it is necessary to model spectral windows using spectrum synthesis with fairly complete line-lists. We have used the LTE spectrum synthesis code ZEEMAN to model the UV spectrum of HD 72660, adjusting abundances for a best match for elements with 6 ≤ Z≤ 82 for which lines are present in the Vinna Atomic Line Database line-list. Abundances or upper limits are derived for 32 elements. We find that except a few, our derived abundances are slightly higher than solar values. We estimate upper limits for abundances of eleven elements and abundance values of 12 elements which have not been detected in the optical. The high abundances that we find for some heavy elements may point to radiative levitation. The presence of lanthanides plus our results, suggest the reclassification of HD 72660 as a transition object between an HgMn star and an Am star.

  10. Synthesis of supported metal nanoparticle catalysts using ligand assisted methods.

    PubMed

    Costa, Natalia J S; Rossi, Liane M

    2012-09-28

    The synthesis and characterization methods of metal nanoparticles (NPs) have advanced greatly in the last few decades, allowing an increasing understanding of structure-property-performance relationships. However, the role played by the ligands used as stabilizers for metal NPs synthesis or for NPs immobilization on solid supports has been underestimated. Here, we highlight some recent progress in the preparation of supported metal NPs with the assistance of ligands in solution or grafted on solid supports, a modified deposition-reduction method, with special attention to the effects on NPs size, metal-support interactions and, more importantly, catalytic activities. After presenting the general strategies in metal NP synthesis assisted by ligands grafted on solid supports, we highlight some recent progress in the deposition of pre-formed colloidal NPs on functionalized solids. Another important aspect that will be reviewed is related to the separation and recovery of NPs. Finally, we will outline our personal understanding and perspectives on the use of supported metal NPs prepared through ligand-assisted methods. PMID:22915064

  11. A new Salen-type azo-azomethine ligand and its Ni(II), Cu(II) and Zn(II) complexes: Synthesis, spectral characterization, crystal structure and photoluminescence studies.

    PubMed

    Ozkan, Gozde; Kose, Muhammet; Zengin, Huseyin; McKee, Vickie; Kurtoglu, Mukerrem

    2015-11-01

    A novel Salen-type azo-azomethine ligand H2agen, 2,2'-{ethane-1,2-diylbis[nitrilomethylylidene]}bis{4-[ethylphenyldiazenyl]phenol}, formed by the 1:2M condensation of ethane-1,2-diamine with 5-[(4-ethylphenyl)diazenyl]-2-hydroxybenzaldehyde and its nickel(II), copper(II), and zinc(II) complexes were synthesized and characterized by the spectroscopic and analytical methods. The UV-vis spectra of the ligand were investigated in three organic solvents (DMSO, DMF and CHCl3). The ligand shows two absorption bands assigned to π-π(∗) and n-π(∗) transitions in the solvents used. Cu(II), and Ni(II) are tetra-coordinate binding to two phenolic oxygens and two imine nitrogens in approximate square planar geometry. Zn(II) also coordinates using the same sites like other metals but gave tetragonal configuration. Molecular structure of the Cu(II) complex [Cu(agen)] was determined by single crystal X-ray diffraction study. The X-ray data revealed that crystallographic imposed symmetry was absent for the complex molecule. In the structure, the Cu(II) ion is coordinated to two phenolate oxygen atoms and two imine nitrogen atoms of the azo-azomethine ligand with approximate square planar geometry. The ligand H2agen and its metal complexes exhibit strong blue emissions with irradiation. Fluorescence quantum yields and excited-state lifetimes for the ligand and its complexes were obtained. The H2agen ligand had a 35% quantum yield and a 3.27 ns excited-state lifetime. Complexation with metal ions caused reductions in intensities and quantum yields. PMID:26123514

  12. Synthesis of the calcilytic ligand NPS 2143

    PubMed Central

    Johansson, Henrik; Cailly, Thomas; Rojas Bie Thomsen, Alex; Bräuner-Osborne, Hans

    2013-01-01

    Summary (R)-3 (NPS 2143) is a negative allosteric modulator of the human calcium-sensing receptor (CaSR) and as such represents an important pharmacological tool compound for studying the CaSR. Herein, we disclose for the first time a complete experimental description, detailed characterisation and assessment of enantiomeric purity for (R)-3. An efficient, reproducible and scalable synthesis of (R)-3 that requires a minimum of chromatographic purification steps is presented. (R)-3 was obtained in excellent optical purity (er > 99:1) as demonstrated by chiral HPLC and the pharmacological profile for (R)-3 is in full accordance with that reported in the literature. PMID:23946832

  13. Natural compounds in the synthesis of chiral organophosphorous ligands

    NASA Astrophysics Data System (ADS)

    Tolstikov, Alexander G.; Khlebnikova, Tatiana B.; Tolstikova, Olga V.; Tolstikov, Genrikh A.

    2003-09-01

    Methods for the synthesis of chiral organophosphorus compounds based on natural optically active compounds (hydroxy acids, amino acids and their derivatives, mono- and disaccharides, mono- and diterpenoids, steroids) are discussed. Particular attention is given to the synthesis of bisphosphines and bisphosphinites. These compounds serve as ligands for transition metal complexes, which catalyse asymmetric hydrogenation. Data on the enantioselectivity of hydrogenation of unsaturated precursors of amino acids and unsaturated prochiral acids as well as on information on the enantioselectivity of hydrosilylation of ketones are surveyed.

  14. Recent developments in the synthesis of nicotinic acetylcholine receptor ligands.

    PubMed

    Breining, Scott R

    2004-01-01

    The extraordinary pharmacology of nicotine and epibatidine have indicated the potential for nicotinic acetylcholine receptor (nAChR) ligands to serve as a new therapeutic class for a host of CNS disorders. Many such ligands are natural products, or analogs thereof, which represent a significant challenge to the synthetic chemist. Synthesis of such molecules often serves as a showcase to demonstrate the potential of newly developed methodology. This synthetic challenge coupled with the promise of pharmacological activity in compounds possessing the nicotinic pharmacophore has stimulated a great deal of synthetic activity over the last five years. The present report provides an overview of novel synthetic methodology occurring during this period directed toward the synthesis of compounds with presumed affinity for the neuronal nAChR. Syntheses chosen for review here represent the major efforts toward molecules such as epibatidine analogs, anatoxin-a, nicotine and related alkaloids, conformationally constrained nicotine derivatives, cytisine and methyllycaconitine (MLA). PMID:14965298

  15. Mono and binuclear Ag(I), Cu(II), Zn(II) and Hg(II) complexes of a new azo-azomethine as ligand: Synthesis, potentiometric, spectral and thermal studies

    NASA Astrophysics Data System (ADS)

    Ahmed, Ibrahim S.; Moustafa, Moustafa M.; Abd El Aziz, Mohamed. M.

    2011-05-01

    New azo-azomethine dyes were prepared by reaction of p-aminobenzoic acid, o-anisidine, o-nitroaniline, and p-bromoaniline with salicylaldehyde respectively to form azo compounds and then condensation by urea to form 4-(R-arylazo 2-salicylaldene)-urea azo-azomethine derivatives (I a-d). The complexes of these ligands with Ag(I), Cu(II), Zn(II) and Hg(II) metal ions were prepared. The structure of the free ligands and their complexes were characterized by using elemental analysis (C, H, N), 1H NMR, IR and UV-Vis-spectra. The proton dissociation constants of the ligands and the stability constant of their complexes have been determined potentiometrically in 40% (v/v) alcohol-water medium as well as the stoichiometry of complexes were determined conductometrically. The data reveal that the stoichiometries for all complexes were prepared in molar ratios (1:1) and (1:2) (M:L). The electrolytic and nonelectrolytic natures of the complexes were assigned based on molar conductance measurements. The thermogravimetric (TG), and differential thermal analyses (DTA) were studied in nitrogen atmosphere with heating rate 10 °C/min. The kinetic and thermodynamic parameters for thermal decomposition of complexes have been calculated by graphical method using Coats-Redfern (CR) method.

  16. Synthesis and characterisation of a mesocyclic tripodal triamine ligand.

    PubMed

    Ure, Andrew D; Lázaro, Isabel Abánades; Cotter, Michelle; McDonald, Aidan R

    2016-01-14

    Meso- and macrocyclic polydentate amine ligands have been widely explored in oxidation catalysis and for the stabilization of unstable metal-superoxide, -peroxide, and -oxo intermediates. Herein we report on the design and synthesis of a novel mesocyclic, tripodal, triamine ligand that we believe will be an excellent addition to this field. We explored a number of synthetic procedures towards the mesocyclic asymmetric tetraalkylated ligand 1. We expect that 1 will bind metals in a facially capping manner, yielding complexes that display pseudo-tetrahedral geometry, potentially providing access to unprecedented late transition metal-oxo complexes (metal = Co, Ni, Cu). We describe the preparation of a library of mesocyclic polyamine synthons (8, 16, 17, 18, 19) that are precursors in the synthesis of 1. These synthons will be used to tailor the electronic properties of metal complexes of 1 and derivatives thereof. The X-ray crystal structures of 19 and mono- and di-protonated forms of 1b show that the triamine crystalises in a boat–chair conformation which is undesirable for metal coordination. However, solution (1)H NMR studies show that in solution both 19 and the tetraalkylated derivative 1b are remarkably flexible. 1b reacted with [CuI(NCCH3)4](OTf) yielding a 1:1 copper(I) complex [CuI(NCCH3)(1b)](+). PMID:26488232

  17. SLGRID: spectral synthesis software in the grid

    NASA Astrophysics Data System (ADS)

    Sabater, J.; Sánchez, S.; Verdes-Montenegro, L.

    2011-11-01

    SLGRID (http://www.e-ciencia.es/wiki/index.php/Slgrid) is a pilot project proposed by the e-Science Initiative of Andalusia (eCA) and supported by the Spanish e-Science Network in the frame of the European Grid Initiative (EGI). The aim of the project was to adapt the spectral synthesis software Starlight (Cid-Fernandes et al. 2005) to the Grid infrastructure. Starlight is used to estimate the underlying stellar populations (their ages and metallicities) using an optical spectrum, hence, it is possible to obtain a clean nebular spectrum that can be used for the diagnostic of the presence of an Active Galactic Nucleus (Sabater et al. 2008, 2009). The typical serial execution of the code for big samples of galaxies made it ideal to be integrated into the Grid. We obtain an improvement on the computational time of order N, being N the number of nodes available in the Grid. In a real case we obtained our results in 3 hours with SLGRID instead of the 60 days spent using Starlight in a PC. The code has already been ported to the Grid. The first tests were made within the e-CA infrastrusture and, later, itwas tested and improved with the colaboration of the CETA-CIEMAT. The SLGRID project has been recently renewed. In a future it is planned to adapt the code for the reduction of data from Integral Field Units where each dataset is composed of hundreds of spectra. Electronic version of the poster at http://www.iaa.es/~jsm/SEA2010

  18. Synthesis, spectral and electrochemical studies of Cu(II) and Ni(II) complexes with new N 2O 2 ligands: A new precursor capable of depositing copper nanoparticles using thermal reduction

    NASA Astrophysics Data System (ADS)

    Habibi, Mohammad Hossein; Mokhtari, Reza; Mikhak, Maryam; Amirnasr, Mehdi; Amiri, Ahmad

    2011-09-01

    Cu(II) and Ni(II) complexes of the general type [M(N 2O 2)] are described. The N 2O 2 ligands used are [N,N'-bis(2-hydroxy-6-methoxybenzylidene)propane-1,3-diamine] (HOMeSalpn) and [N,N'-bis(2-hydroxy-6-methoxybenzylidene)propane-1,2-diamine (HOMeSalpr). These complexes have been characterized by IR, UV-vis, CV, TG-DTA and 1H NMR spectroscopy. The electrochemical behavior of these complexes at a glassy carbon electrode in acetonitrile solution indicates that the first reduction process corresponding to Cu(II)-Cu(I) and Ni(II)-Ni(I) is electrochemically irreversible. The new copper complexes have been applied for the preparation of copper nanoparticles using non-ionic surfactant (Triton X-100) by thermal reduction. The copper nanoparticles with average size of 48 nm were formed by thermal reduction of [N,N'-bis(2-hydroxy-6-methoxybenzylidene)propane-1,3-diamine]copper(II) in the presence of triphenylphosphine thus releasing the reduced copper and affording the high-purity copper nanoparticles.

  19. Synthesis, spectral and electrochemical studies of Cu(II) and Ni(II) complexes with new N2O2 ligands: a new precursor capable of depositing copper nanoparticles using thermal reduction.

    PubMed

    Habibi, Mohammad Hossein; Mokhtari, Reza; Mikhak, Maryam; Amirnasr, Mehdi; Amiri, Ahmad

    2011-09-01

    Cu(II) and Ni(II) complexes of the general type [M(N2O2)] are described. The N2O2 ligands used are [N,N'-bis(2-hydroxy-6-methoxybenzylidene)propane-1,3-diamine] (HOMeSalpn) and [N,N'-bis(2-hydroxy-6-methoxybenzylidene)propane-1,2-diamine (HOMeSalpr). These complexes have been characterized by IR, UV-vis, CV, TG-DTA and 1H NMR spectroscopy. The electrochemical behavior of these complexes at a glassy carbon electrode in acetonitrile solution indicates that the first reduction process corresponding to Cu(II)-Cu(I) and Ni(II)-Ni(I) is electrochemically irreversible. The new copper complexes have been applied for the preparation of copper nanoparticles using non-ionic surfactant (Triton X-100) by thermal reduction. The copper nanoparticles with average size of 48nm were formed by thermal reduction of [N,N'-bis(2-hydroxy-6-methoxybenzylidene)propane-1,3-diamine]copper(II) in the presence of triphenylphosphine thus releasing the reduced copper and affording the high-purity copper nanoparticles. PMID:21641857

  20. Trinuclear Zinc(II) Complexes and Polymeric Cadmium(II) Complexes with the Ligand 2,5-Bis(2-pyridyl)pyrazine: Synthesis, Spectral Analysis, and Single-Crystal and Powder X-ray Analyses.

    PubMed

    Neels, Antonia; Stoeckli-Evans, Helen

    1999-12-27

    Three zinc compounds, [ZnCl(2)(bppz)(dmf)] (1), [Zn(3)(OAc)(6)(bppz)(2)](H(2)O) (2), and [Zn(3)(Cl)(6)(bppz)(3)](H(2)O) (3), and two cadmium complexes, {[Cd(OAc)(2)(bppz)](H(2)O)(5)}(n)() (4) and [Cd(NO(3))(2)(bppz)](n)() (5), where bppz is 2,5-bis(2-pyridyl)pyrazine, have been synthesized and characterized spectroscopically and crystallographically. The mononuclear complex 1, C(17)H(17)Cl(2)N(5)OZn, crystallizes in the monoclinic space group P2(1)/c, with a = 8.654(1) Å, b = 9.500(1) Å, c = 22.997(1) Å, beta = 97.99(1) degrees, and Z = 4; R1 for 2356 observed reflections [I > 2sigma(I)] was 0.058. The zinc atom has a distorted square planar coordination sphere with the ligand bppz connected in a mono-bidentate manner. The remaining coordination sites are occupied by the chloride counterions and by an oxygen atom of a solvent molecule. The trinuclear zinc compound 2, C(40)H(38)N(8)O(12)Zn(3).H(2)O, crystallizes in the triclinic space group P&onemacr;, with a = 12.238(4) Å, b = 12.986(3) Å, c = 15.470(4) Å, alpha = 75.65(1) degrees, beta = 97.99(1) degrees, gamma = 65.98(1) degrees, and Z = 2; R1 for 4511 observed reflections [I > 2sigma(I)] was 0.07. This complex consists of a linear arrangement of three zinc atoms. The central zinc atom, located on a crystallographic inversion center, is connected by six bridging acetate groups to two symmetry-related zinc atoms. It has an almost perfect octahedral coordination environment. The outer symmetry-related zinc atoms are in a square pyramidal environment, and they coordinate to three acetate groups and to one bppz molecule in a mono-bidentate manner. Compound 3, C(42)H(30)Cl(6)N(12)Zn(3).1.25H(2)O, a cyclic zinc(II) trimer, crystallizes in the cubic space group Ia&thremacr;d, with a = 26.311(1) Å and Z = 16; R1 for 692 observed reflections [I > 2sigma(I)] was 0.038. This trinuclear complex has a perfect triangular arrangement of the zinc atoms. Each zinc atom is connected to the other two by a bppz molecule. The

  1. Synthesis, spectroscopic, thermogravimetric and antimicrobial studies of mixed ligands complexes

    NASA Astrophysics Data System (ADS)

    Mahmoud, Walaa H.; Mahmoud, Nessma F.; Mohamed, Gehad G.; El-Sonbati, Adel Z.; El-Bindary, Ashraf A.

    2015-09-01

    An interesting series of mixed ligand complexes have been synthesized by the reaction of metal chloride with guaifenesin (GFS) in the presence of 2-aminoacetic acid (HGly) (1:1:1 molar ratio). The elemental analysis, magnetic moments, molar conductance, spectral (UV-Vis, IR, 1H NMR and ESR) and thermal studies were used to characterize the isolated complexes. The molecular structure of GFS is optimized theoretically and the quantum chemical parameters are calculated. The IR showed that the ligand (GFS) acts as monobasic tridentate through the hydroxyl, phenoxy etheric and methoxy oxygen atoms and co-ligand (HGly) as monobasic bidentate through the deprotonated carboxylate oxygen atom and nitrogen atom of amino group. The molar conductivities showed that all the complexes are non-electrolytes except Cr(III) complex is electrolyte. Electronic and magnetic data proposed the octahedral structure for all complexes under investigation. ESR spectrum for Cu(II) revealed data which confirm the proposed structure. Antibacterial screening of the compounds were carried out in vitro on gram positive (Bacillus subtilis and Staphylococcus aureus), gram negative (Escherichia coli and Neisseria gonorrhoeae) bacteria and for in vitro antifungal activity against Candida albicans organism. However, some complexes showed more chemotherapeutic efficiency than the parent GFS drug. The complexes were also screened for their in vitro anticancer activity against the breast cell line (MFC7) and the results obtained showed that they exhibit a considerable anticancer activity.

  2. A simple model-free method for direct assessment of fluorescent ligand binding by linear spectral summation.

    PubMed

    Gasymov, Oktay K; Abduragimov, Adil R; Glasgow, Ben J

    2014-01-01

    Fluorescent tagged ligands are commonly used to determine binding to proteins. However, bound and free ligand concentrations are not directly determined. Instead the response in a fluorescent ligand titration experiment is considered to be proportional to the extent of binding and, therefore, the maximum value of binding is scaled to the total protein concentration. Here, a simple model-free method is presented to be performed in two steps. In the first step, normalized bound and free spectra of the ligand are determined. In the second step, these spectra are used to fit composite spectra as the sum of individual components or linear spectral summation. Using linear spectral summation, free and bound 1-Anilinonaphthalene-8-Sulfonic Acid (ANS) fluorescent ligand concentrations are directly calculated to determine ANS binding to tear lipocalin (TL), an archetypical ligand binding protein. Error analysis shows that the parameters that determine bound and free ligand concentrations were recovered with high certainty. The linear spectral summation method is feasible when fluorescence intensity is accompanied by a spectral shift upon protein binding. Computer simulations of the experiments of ANS binding to TL indicate that the method is feasible when the fluorescence spectral shift between bound and free forms of the ligand is just 8 nm. Ligands tagged with environmentally sensitive fluorescent dyes, e.g., dansyl chromophore, are particularly suitable for this method. PMID:24043458

  3. A Simple Model-Free Method for Direct Assessment of Fluorescent Ligand Binding by Linear Spectral Summation

    PubMed Central

    Gasymov, Oktay K.; Abduragimov, Adil R.; Glasgow, Ben J.

    2013-01-01

    Fluorescent tagged ligands are commonly used to determine binding to proteins. However, bound and free ligand concentrations are not directly determined. Instead the response in a fluorescent ligand titration experiment is considered to be proportional to the extent of binding and, therefore, the maximum value of binding is scaled to the total protein concentration. Here, a simple model-free method is presented to be performed in two steps. In the first step, normalized bound and free spectra of the ligand are determined. In the second step, these spectra are used to fit composite spectra as the sum of individual components or linear spectral summation. Using linear spectral summation, free and bound 1-Anilinonaphthalene-8-Sulfonic Acid (ANS) fluorescent ligand concentrations are directly calculated to determine ANS binding to tear lipocalin (TL), an archetypical ligand binding protein. Error analysis shows that the parameters that determine bound and free ligand concentrations were recovered with high certainty. The linear spectral summation method is feasible when fluorescence intensity is accompanied by a spectral shift upon protein binding. Computer simulations of the experiments of ANS binding to TL indicate that the method is feasible when the fluorescence spectral shift between bound and free forms of the ligand is just 8 nm. Ligands tagged with environmentally sensitive fluorescent dyes, e.g., dansyl chromophore, are particularly suitable for this method. PMID:24043458

  4. Microwave assisted synthesis, spectral, magnetic and bioevolution of few Mn (II)-amide complexes

    NASA Astrophysics Data System (ADS)

    Joshi, Gaurav; Verma, K. K.; Gudesaria, D. D.; Bhojak, N.

    2016-05-01

    The importance and versatility of amide group containing ligands have promoted the selection of this class of ligands and their complexes for the study. The present work describes the synthesis, spectral and biological investigations on the complexes of amides derived from heterocyclic amines with Mn (II) ions. Four ligands derived 2-aminopyridine and their complexes with Mn (II) have been synthesized. A method for the synthesis of complexes has been developed by the use of microwave irradiation which is in agreement to Green chemistry approach. The complexes have been characterized on the basis of elemental analysis, infrared, electronic, ESR spectra and magnetic susceptibility studies. The diffuse reflectance spectrum of the complexes show bands in the region 20,000 cm-1 to 26,000 cm-1 assignable to 6A1g → 4T2g and 6A1g → 4E1g transitions. These are also typical of tetrahedral environment around the manganese. The magnetic moment (5.80 BM) of the complex indicates high spin tetrahedral environment. The microwave method of synthesis of complexes have been found easier, convenient and ecofriendly. Antimicrobial activities of compounds were also carried out against bacteria and fungi. Further minimal inhibitory concentration (MIC) was also determined for each compound.

  5. Sulfur copolymer for the direct synthesis of ligand-free CdS nanoparticles.

    PubMed

    Martin, Trevor R; Mazzio, Katherine A; Hillhouse, Hugh W; Luscombe, Christine K

    2015-06-30

    Organic coordinating ligands are ubiquitously used to solubilize, stabilize and functionalize colloidal nanoparticles. Aliphatic organic ligands are typically used to control size during the nanoparticle growth period and are used as a high boiling point solvent for solution-based synthesis procedures. However, these aliphatic ligands are typically not well suited for the end use of the nanoparticles, so additional ligand exchange or ligand stripping procedures must be implemented after the nanoparticle synthesis. Herein we present a ligand-free CdS nanoparticle synthesis procedure using a unique sulfur copolymer. The sulfur copolymer is derived from elemental sulfur, which is a cheap and abundant material. This copolymer is used as a sulfur source and high boiling point solvent, which produces stabilized metal-sulfide nanoparticles that are suspended within a sulfur copolymer matrix. The copolymer can then be removed, thereby yielding ligand-free metal-sulfide nanoparticles. PMID:26077505

  6. Laser ablation synthesis and spectral characterization of ruby nanoparticles

    NASA Astrophysics Data System (ADS)

    Baranov, M. S.; Bardina, A. A.; Savelyev, A. G.; Khramov, V. N.; Khaydukov, E. V.

    2016-04-01

    The laser ablation method was implemented for synthesis of ruby nanoparticles. Nanoparticles were obtained by nanosecond ablation of bulk ruby crystal in 10% ethanol water solution. The nanoparticles enable water colloid stability and exhibit narrow photoluminescent line at 694 nm when pumped at blue-green spectral range. The ruby nanoparticles were characterized by SEM and Z-sizer.

  7. On spectral synthesis on element-wise compact Abelian groups

    NASA Astrophysics Data System (ADS)

    Platonov, S. S.

    2015-08-01

    Let G be an arbitrary locally compact Abelian group and let C(G) be the space of all continuous complex-valued functions on G. A closed linear subspace \\mathscr H\\subseteq C(G) is referred to as an invariant subspace if it is invariant with respect to the shifts τ_y\\colon f(x)\\mapsto f(xy), y\\in G. By definition, an invariant subspace \\mathscr H\\subseteq C(G) admits strict spectral synthesis if \\mathscr H coincides with the closure in C(G) of the linear span of all characters of G belonging to \\mathscr H. We say that strict spectral synthesis holds in the space C(G) on G if every invariant subspace \\mathscr H\\subseteq C(G) admits strict spectral synthesis. An element x of a topological group G is said to be compact if x is contained in some compact subgroup of G. A group G is said to be element-wise compact if all elements of G are compact. The main result of the paper is the proof of the fact that strict spectral synthesis holds in C(G) for a locally compact Abelian group G if and only if G is element-wise compact. Bibliography: 14 titles.

  8. Polycatenar Ligand Control of the Synthesis and Self-Assembly of Colloidal Nanocrystals.

    PubMed

    Diroll, Benjamin T; Jishkariani, Davit; Cargnello, Matteo; Murray, Christopher B; Donnio, Bertrand

    2016-08-24

    Hydrophobic colloidal nanocrystals are typically synthesized and manipulated with commercially available ligands, and surface functionalization is therefore typically limited to a small number of molecules. Here, we report the use of polycatenar ligands derived from polyalkylbenzoates for the direct synthesis of metallic, chalcogenide, pnictide, and oxide nanocrystals. Polycatenar molecules, branched structures bearing diverging chains in which the terminal substitution pattern, functionality, and binding group can be independently modified, offer a modular platform for the development of ligands with targeted properties. Not only are these ligands used for the direct synthesis of monodisperse nanocrystals, but nanocrystals coated with polycatenar ligands self-assemble into softer bcc superlattices that deviate from conventional harder close-packed structures (fcc or hcp) formed by the same nanocrystals coated with commercial ligands. Self-assembly experiments demonstrate that the molecular structure of polycatenar ligands encodes interparticle spacings and attractions, engineering self-assembly, which is tunable from hard sphere to soft sphere behavior. PMID:27472457

  9. Ligand-protected gold clusters: the structure, synthesis and applications

    NASA Astrophysics Data System (ADS)

    Pichugina, D. A.; Kuz'menko, N. E.; Shestakov, A. F.

    2015-11-01

    Modern concepts of the structure and properties of atomic gold clusters protected by thiolate, selenolate, phosphine and phenylacetylene ligands are analyzed. Within the framework of the superatom theory, the 'divide and protect' approach and the structure rule, the stability and composition of a cluster are determined by the structure of the cluster core, the type of ligands and the total number of valence electrons. Methods of selective synthesis of gold clusters in solution and on the surface of inorganic composites based, in particular, on the reaction of Aun with RS, RSe, PhC≡C, Hal ligands or functional groups of proteins, on stabilization of clusters in cavities of the α-, β and γ-cyclodextrin molecules (Au15 and Au25) and on anchorage to a support surface (Au25/SiO2, Au20/C, Au10/FeOx) are reviewed. Problems in this field are also discussed. Among the methods for cluster structure prediction, particular attention is given to the theoretical approaches based on the density functional theory (DFT). The structures of a number of synthesized clusters are described using the results obtained by X-ray diffraction analysis and DFT calculations. A possible mechanism of formation of the SR(AuSR)n 'staple' units in the cluster shell is proposed. The structure and properties of bimetallic clusters MxAunLm (M=Pd, Pt, Ag, Cu) are discussed. The Pd or Pt atom is located at the centre of the cluster, whereas Ag and Cu atoms form bimetallic compounds in which the heteroatom is located on the surface of the cluster core or in the 'staple' units. The optical properties, fluorescence and luminescence of ligand-protected gold clusters originate from the quantum effects of the Au atoms in the cluster core and in the oligomeric SR(AuSR)x units in the cluster shell. Homogeneous and heterogeneous reactions catalyzed by atomic gold clusters are discussed in the context of the reaction mechanism and the nature of the active sites. The bibliography includes 345 references.

  10. Synthesis and characterization of mixed ligand chiral nanoclusters.

    PubMed

    Guven, Zekiye P; Ustbas, Burcin; Harkness, Kellen M; Coskun, Hikmet; Joshi, Chakra P; Besong, Tabot M D; Stellacci, Francesco; Bakr, Osman M; Akbulut, Ozge

    2016-07-28

    Chiral mixed ligand silver nanoclusters were synthesized in the presence of a chiral and an achiral ligand. While the chiral ligand led mostly to the formation of nanoparticles, the presence of the achiral ligand drastically increased the yield of nanoclusters with enhanced chiral properties. PMID:27362744

  11. Synthesis of Ligand-free CdS Nanoparticles within a Sulfur Copolymer Matrix.

    PubMed

    Martin, Trevor R; Mazzio, Katherine A; Hillhouse, Hugh W; Luscombe, Christine K

    2016-01-01

    Aliphatic ligands are typically used during the synthesis of nanoparticles to help mediate their growth in addition to operating as high-temperature solvents. These coordinating ligands help solubilize and stabilize the nanoparticles while in solution, and can influence the resulting size and reactivity of the nanoparticles during their formation. Despite the ubiquity of using ligands during synthesis, the presence of aliphatic ligands on the nanoparticle surface can result in a number of problems during the end use of the nanoparticles, necessitating further ligand stripping or ligand exchange procedures. We have developed a way to synthesize cadmium sulfide (CdS) nanoparticles using a unique sulfur copolymer. This sulfur copolymer is primarily composed of elemental sulfur, which is a cheap and abundant material. The sulfur copolymer has the advantages of operating both as a high temperature solvent and as a sulfur source, which can react with a cadmium precursor during nanoparticle synthesis, resulting in the generation of ligand free CdS. During the reaction, only some of the copolymer is consumed to produce CdS, while the rest remains in the polymeric state, thereby producing a nanocomposite material. Once the reaction is finished, the copolymer stabilizes the nanoparticles within a solid polymeric matrix. The copolymer can then be removed before the nanoparticles are used, which produces nanoparticles that do not have organic coordinating ligands. This nascent synthesis technique presents a method to produce metal-sulfide nanoparticles for a wide variety of applications where the presence of organic ligands is not desired. PMID:27167155

  12. RADIATION SPECTRAL SYNTHESIS OF RELATIVISTIC FILAMENTATION

    SciTech Connect

    Frederiksen, Jacob Trier; Haugboelle, Troels; Medvedev, Mikhail V.; Nordlund, Ake

    2010-10-10

    Radiation from many astrophysical sources, e.g., gamma-ray bursts and active galactic nuclei, is believed to arise from relativistically shocked collisionless plasmas. Such sources often exhibit highly transient spectra evolving rapidly compared with source lifetimes. Radiation emitted from these sources is typically associated with nonlinear plasma physics, complex field topologies, and non-thermal particle distributions. In such circumstances, a standard synchrotron paradigm may fail to produce accurate conclusions regarding the underlying physics. Simulating spectral emission and spectral evolution numerically in various relativistic shock scenarios is then the only viable method to determine the detailed physical origin of the emitted spectra. In this Letter, we present synthetic radiation spectra representing the early stage development of the filamentation (streaming) instability of an initially unmagnetized plasma, which is relevant for both collisionless shock formation and reconnection dynamics in relativistic astrophysical outflows as well as for laboratory astrophysics experiments. Results were obtained using a highly efficient in situ diagnostics method, based on detailed particle-in-cell modeling of collisionless plasmas. The synthetic spectra obtained here are compared with those predicted by a semi-analytical model for jitter radiation from the filamentation instability, the latter including self-consistent generated field topologies and particle distributions obtained from the simulations reported upon here. Spectra exhibit dependence on the presence-or the absence-of an inert plasma constituent, when comparing baryonic plasmas (i.e., containing protons) with pair plasmas. The results also illustrate that considerable care should be taken when using lower-dimensional models to obtain information about the astrophysical phenomena generating observed spectra.

  13. Radiation Spectral Synthesis of Relativistic Filamentation

    NASA Astrophysics Data System (ADS)

    Frederiksen, Jacob Trier; Haugbølle, Troels; Medvedev, Mikhail V.; Nordlund, Åke

    2010-10-01

    Radiation from many astrophysical sources, e.g., gamma-ray bursts and active galactic nuclei, is believed to arise from relativistically shocked collisionless plasmas. Such sources often exhibit highly transient spectra evolving rapidly compared with source lifetimes. Radiation emitted from these sources is typically associated with nonlinear plasma physics, complex field topologies, and non-thermal particle distributions. In such circumstances, a standard synchrotron paradigm may fail to produce accurate conclusions regarding the underlying physics. Simulating spectral emission and spectral evolution numerically in various relativistic shock scenarios is then the only viable method to determine the detailed physical origin of the emitted spectra. In this Letter, we present synthetic radiation spectra representing the early stage development of the filamentation (streaming) instability of an initially unmagnetized plasma, which is relevant for both collisionless shock formation and reconnection dynamics in relativistic astrophysical outflows as well as for laboratory astrophysics experiments. Results were obtained using a highly efficient in situ diagnostics method, based on detailed particle-in-cell modeling of collisionless plasmas. The synthetic spectra obtained here are compared with those predicted by a semi-analytical model for jitter radiation from the filamentation instability, the latter including self-consistent generated field topologies and particle distributions obtained from the simulations reported upon here. Spectra exhibit dependence on the presence—or the absence—of an inert plasma constituent, when comparing baryonic plasmas (i.e., containing protons) with pair plasmas. The results also illustrate that considerable care should be taken when using lower-dimensional models to obtain information about the astrophysical phenomena generating observed spectra.

  14. A modular approach to neutral P,N-ligands: synthesis and coordination chemistry

    PubMed Central

    Blasius, Clemens K; Intorp, Sebastian N; Wadepohl, Hubert

    2016-01-01

    Summary We report the modular synthesis of three different types of neutral κ2-P,N-ligands comprising an imine and a phosphine binding site. These ligands were reacted with rhodium, iridium and palladium metal precursors and the structures of the resulting complexes were elucidated by means of X-ray crystallography. We observed that subtle changes of the ligand backbone have a significant influence on the binding geometry und coordination properties of these bidentate P,N-donors. PMID:27340475

  15. Ligand Effects on Synthesis and Post-Synthetic Stability of PbSe Nanocrystals

    SciTech Connect

    Dai, Quanqin; Zhang, Yu; Wang, Yingnan; Hu, Michael Z.

    2010-01-01

    This paper reports the effect of ligands including oleic acid (OA), trioctylphosphine (TOP), and tributylphosphine (TBP) on the PbSe nanocrystal growth during synthesis, as well as the effect of OA ligands on the nanocrystal stability after synthesis. These ligands play important roles in the nucleation and growth mechanism of nanocrystals. We have discovered that the ligand effect on the growth of PbSe nanocrystals can differ from that on the mostly studied CdSe nanocrystals. Also, we present a method for producing relatively smaller and more monodisperse PbSe nanocrystals based on our new understanding that the use of TBP, instead of the generally reported TOP, can slow down the growth of PbSe nanocrystals. In addition, our postsynthetic investigation of OA ligand effects demonstrate the dominant desorption of OA-bonded Pb atoms, causing the shrinkage of PbSe nanocrystals. This provides some insight into stabilization strategies for labile PbSe nanocrystals.

  16. Effects of prosodic factors on spectral dynamics. II. Synthesis

    NASA Astrophysics Data System (ADS)

    Wouters, Johan; Macon, Michael W.

    2002-01-01

    In Paper I [J. Wouters and M. Macon, J. Acoust. Soc. Am. 111, 417-427 (2002)], the effects of prosodic factors on the spectral rate of change of phoneme transitions were analyzed for a balanced speech corpus. The results showed that the spectral rate of change, defined as the root-mean-square of the first three formant slopes, increased with linguistic prominence, i.e., in stressed syllables, in accented words, in sentence-medial words, and in clearly articulated speech. In the present paper, an initial approach is described to integrate the results of Paper I in a concatenative synthesis framework. The target spectral rate of change of acoustic units is predicted based on the prosodic structure of utterances to be synthesized. Then, the spectral shape of the acoustic units is modified according to the predicted spectral rate of change. Experiments show that the proposed approach provides control over the degree of articulation of acoustic units, and improves the naturalness and intelligibility of concatenated speech in comparison to standard concatenation methods.

  17. Microwave-assisted Organic Synthesis of a High-affinity Pyrazolo-pyrimidinyl TSPO Ligand

    PubMed Central

    Tang, Dewei; Buck, Jason R.; Hight, Matthew R.; Manning, H. Charles

    2010-01-01

    We herein report a dramatically improved total synthesis of the high-affinity translocator protein (TSPO) ligand DPA-714, featuring microwave-assisted organic synthesis (MAOS). Compared with previously described approaches, our novel MAOS method dramatically reduces overall reaction time without adversely effecting reaction yields. We envision that the described MAOS protocol may be suitably applied to high-throughput, diversity-oriented synthesis of novel compounds based on the pyrazolo-pyrimidinyl scaffold. Such an approach could accelerate the development of focused libraries of novel TSPO ligands with potential for future development as molecular imaging and therapeutic agents. PMID:20689673

  18. Studies on electronic spectral parameters of doped Nd(III) ion with therapeutically important ligands in dioxane solvent

    NASA Astrophysics Data System (ADS)

    Bajaj, Annu; Jain, Sushma

    2016-05-01

    The present investigation is concerened with the studies on electronic spectral parameters viz. Oscillator strength (P), Judd-Ofelt Tλ (λ=2,4,6), Slater-Condon(FK),Lande(ζ4F),Nephelauxetic ratio(β), Bonding parameter (b1/2) and Percent covalency parameter (δ%) for Nd(III) ion complexes with the ligands having Nitrogen,Oxygen Sulphur donor sites.The variation in the values of oscillator strength explicitly shows the relative sensitivities of the 4f-4f transition as well as the specific correlation between ligand structures and nature of Nd(III) ligand interaction.

  19. Microchemical synthesis of the serotonin receptor ligand, /sup 125/I-LSD

    SciTech Connect

    Hartig, P.R.; Krohn, A.M.; Hirschman, S.A.

    1985-02-01

    The synthesis and properties of 2-(/sup 125/I)-lysergic acid diethylamide, the first /sup 125/I-labeled serotonin receptor ligand, are described. A novel microsynthesis apparatus was developed for this synthesis. The apparatus employs a micromanipulator and glass micro tools to handle microliter to nanoliter volumes on a microscope stage. This apparatus should be generally useful for the synthesis of radioligands and other compounds when limited amounts of material must be handled in small volumes.

  20. Spectral Envelopes and Additive + Residual Analysis/Synthesis

    NASA Astrophysics Data System (ADS)

    Rodet, Xavier; Schwarz, Diemo

    The subject of this chapter is the estimation, representation, modification, and use of spectral envelopes in the context of sinusoidal-additive-plus-residual analysis/synthesis. A spectral envelope is an amplitude-vs-frequency function, which may be obtained from the envelope of a short-time spectrum (Rodet et al., 1987; Schwarz, 1998). [Precise definitions of such an envelope and short-time spectrum (STS) are given in Section 2.] The additive-plus-residual analysis/synthesis method is based on a representation of signals in terms of a sum of time-varying sinusoids and of a non-sinusoidal residual signal [e.g., see Serra (1989), Laroche et al. (1993), McAulay and Quatieri (1995), and Ding and Qian (1997)]. Many musical sound signals may be described as a combination of a nearly periodic waveform and colored noise. The nearly periodic part of the signal can be viewed as a sum of sinusoidal components, called partials, with time-varying frequency and amplitude. Such sinusoidal components are easily observed on a spectral analysis display (Fig. 5.1) as obtained, for instance, from a discrete Fourier transform.

  1. Synthesis, characterization and antibacterial studies on some mixed ligand thorium complexes with N- and O-donor ligands.

    PubMed

    Patil, Sunil S; Thakur, Ganesh A; Shaikh, Manzoor M

    2011-01-01

    Mixed ligand Th(IV) complexes of the type [M(Q)(L)(NO3)2] x 2H2O have been synthesized using 8-hydroxyquinoline (HQ) as a primary ligand and N- and/or O- donor amino acids (HL) such as L-threonine, L-tryptophan and L-isoleucine as secondary ligands. The metal complexes have been characterized on the basis of elemental analysis, electrical conductance, room temperature magnetic susceptibility measurements, spectral and thermal studies. The electrical conductance studies of the complexes in DMF in 10(-3). M concentration indicate their non-electrolytic nature. Room temperature magnetic susceptibility measurements revealed diamagnetic nature of the complexes. Electronic absorption spectra of the complexes show intra-ligand and charge transfer transitions, respectively. Bonding of the metal ion through N- and O-donor atoms of the ligands revealed by IR studies and the chemical environment of the protons is also confirmed by NMR studies. The thermal analysis data of the complexes indicate the presence of crystalline water molecules. The tube dilution method has been used to study the antibacterial activity of the complexes against the pathogenic bacteria S. aureus, C. diphtheriae, S. typhi and E. coli. PMID:22125953

  2. Synthesis of 3-alkyl naphthalenes as novel estrogen receptor ligands

    SciTech Connect

    Fang, Jing; Akwabi-Ameyaw, Adwoa; Britton, Jonathan E.; Katamreddy, Subba R.; Navas III, Frank; Miller, Aaron B.; Williams, Shawn P.; Gray, David W.; Orband-Miller, Lisa A.; Shearin, Jean; Heyer, Dennis

    2009-06-24

    A series of estrogen receptor ligands based on a 3-alkyl naphthalene scaffold was synthesized using an intramolecular enolate-alkyne cycloaromatization as the key step. Several of these compounds bearing a C6-OH group were shown to be high affinity ligands. All compounds had similar ER{alpha} and ER{beta} binding affinity ranging from micromolar to low nanomolar.

  3. On spectral synthesis on zero-dimensional Abelian groups

    SciTech Connect

    Platonov, S S

    2013-09-30

    Let G be a zero-dimensional locally compact Abelian group all of whose elements are compact, and let C(G) be the space of all complex-valued continuous functions on G. A closed linear subspace H⊆C(G) is said to be an invariant subspace if it is invariant with respect to the translations τ{sub y}:f(x)↦f(x+y), y∈G. In the paper, it is proved that any invariant subspace H admits spectral synthesis, that is, H coincides with the closed linear span of the characters of G belonging to H. Bibliography: 25 titles.

  4. Differential Spectral Synthesis of Low-Luminosity Elliptical Galaxies

    NASA Astrophysics Data System (ADS)

    Jones, Lewis Alexander

    In this thesis, a study of the spectral variations in the integrated light of eight low-luminosity elliptical galaxies is presented. The unique opportunity provided by low-luminosity elliptical galaxies to study integrated spectra at high line definition is the motivation behind the observational approach for this study. A long wavelength baseline is sacrificed in favor of working at high resolution (~2 Å FWHM) with a large variety of narrow absorption features in a smaller wave-length window. A new spectral library has been developed with this approach in mind. The library consists of spectra of 684 stars all observed with the Coudé Feed Telescope and Spectrograph at the Kitt Peak National Observatory, covering the spectral ranges 3820-4500 Å and 4780-5450 Å and at a spectral resolution of ~2 Å FWHM. The coverage of the library is complete for spectral types A-K and luminosity classes I-V, in the range -2.5 <= FeH; <= +0.5, while the O, B, and M stars are near solar. The empirical investigation of the galaxy spectra in reference to the stellar sequences of the spectral library yields several key results. (1) There is a spread in the mean spectral types of the low-luminosity ellliptical galaxies. (2) The galaxies are similar in evolved star content, Fe line strengths, and their evolved star light is dominated by solar type giants. (3) Five of the eight galaxies are shown to contain less than a 5% hot star contribution, which is inconsistent with the prediction of ~10% from the simple model of chemical evolution (Worthey, Dorman, and Jones 1996). (4) From variations in the balance of dwarf and giant light in the galaxy spectra it is claimed that there is a spread in the mean stellar ages of the low-luminosity elliptical galaxies. These results are interpreted in the context of the evolutionary synthesis models of Worthey (1994). The main result from the comparison of the galaxies and models is that the low-luminosity elliptical galaxies show a large spread in

  5. Anion directed structural diversity in zinc complexes with conformationally flexible quinazoline ligand: structural, spectral and theoretical studies.

    PubMed

    Dwivedi, Nidhi; Panja, Sumit Kumar; Monika; Saha, Satyen; Sunkari, Sailaja S

    2016-08-14

    In this paper, we report the synthesis, structure and photophysical studies of four new complexes of conformationally flexible 6-chloro-4-phenyl-2-(pyridin-2-yl)quinazoline ligand (L) with Zn(ii). The coordinating ability of the ligand and geometrical preferences of the resultant complexes are tuned by varying the anion of the metal salt as confirmed by structural and DFT studies. The choice of the metal salt (especially anion) directs the stabilisation of different conformations of the ligand arising out of twisting of the pyridyl ring with respect to the quinazoline ring, resulting in complexes with different nuclearity (monomer/dimer) as well as different coordination geometries (tetrahedral/trigonal bipyramidal/octahedral). Photophysical properties are also found to be tuned due to conformational changes on complexation. DFT studies on the ligand establish the conformationally stable forms as observed in the reported structures. PMID:27397771

  6. Mixed ligand complexes of bis(phenylimine) Schiff base ligands incorporating pyridinium moiety. Synthesis, characterization and antibacterial activity

    NASA Astrophysics Data System (ADS)

    Mohamed, Gehad G.; El-Wahab, Zeinab H. Abd

    2005-04-01

    The synthesis and structural characterization of mixed ligand complexes derived from 2,6-pyridinedicarboxaldehydebis( o-hydroxyphenylimine), 2,6-pyridinedicarboxaldehydebis( p-hydroxyphenylimine) (1 ry ligands) and 2-aminopyridne (2 ry ligand) are reported. The ligands and their transition metal complexes were characterized on the bases of their elemental analyses, IR, solid reflectance, magnetic moment, molar conductance and thermal analysis (TGA). The mixed ligand complexes are formed in the 1:1:1 (M:L 1 or L 2:L') ratio as found from the elemental analyses and found to have the formulae [MX 2(L 1 or L 2)(L')]· nH 2O where M = Co(II), Ni(II), Cu(II) and Zn(II), L 1 = 2,6-pyridinedicarboxaldehydebis( p-hydroxyphenylimine), L 2 = 2,6-pyridine dicarboxaldehydebis( o-hydroxyphenylimine), L' = 2-aminopyridine, X = Cl - in case of Cu(II) complex and Br - in case of Co(II), Ni(II) and Zn(II) complexes and y = 0-3. The molar conductance data reveal that the chelates are non-electrolytes. IR spectra show that the Schiff bases are coordinated to the metal ions in a terdentate manner with NNN donor sites of the pyridine- N and two azomethine- N. While 2-aminopyridine coordinated to the metal ions via its pyridine- N. Magnetic and solid reflectance spectra are used to infer the coordinating capacity of the ligand and the geometrical structure of these complexes are found to be octahedral. The thermal behaviour of these chelates shows that the hydrated water molecules and the anions are removed in a successive two steps followed immediately by decomposition of the ligands (L 1, L 2 and L') in the subsequent steps. The activation thermodynamic parameters, such as, E*, Δ H*, Δ S* and Δ G* are calculated from the TG curves and discussed. The ligands and their metal chelates have been screened for their antimicrobial activities and the findings have been reported, explained and compared with some known antibiotics.

  7. Mixed ligand complexes of bis(phenylimine) Schiff base ligands incorporating pyridinium moiety Synthesis, characterization and antibacterial activity.

    PubMed

    Mohamed, Gehad G; Abd El-Wahab, Zeinab H

    2005-04-01

    The synthesis and structural characterization of mixed ligand complexes derived from 2,6-pyridinedicarboxaldehydebis(o-hydroxyphenylimine), 2,6-pyridinedicarboxaldehydebis(p-hydroxyphenylimine) (1(ry) ligands) and 2-aminopyridne (2(ry) ligand) are reported. The ligands and their transition metal complexes were characterized on the bases of their elemental analyses, IR, solid reflectance, magnetic moment, molar conductance and thermal analysis (TGA). The mixed ligand complexes are formed in the 1:1:1 (M:L(1) or L(2):L') ratio as found from the elemental analyses and found to have the formulae [MX(2)(L(1) or L(2))(L')].nH(2)O where M = Co(II), Ni(II), Cu(II) and Zn(II), L(1) = 2,6-pyridinedicarboxaldehydebis(p-hydroxyphenylimine), L(2) = 2,6-pyridine dicarboxaldehydebis(o-hydroxyphenylimine), L' = 2-aminopyridine, X = Cl(-) in case of Cu(II) complex and Br(-) in case of Co(II), Ni(II) and Zn(II) complexes and y = 0-3. The molar conductance data reveal that the chelates are non-electrolytes. IR spectra show that the Schiff bases are coordinated to the metal ions in a terdentate manner with NNN donor sites of the pyridine-N and two azomethine-N. While 2-aminopyridine coordinated to the metal ions via its pyridine-N. Magnetic and solid reflectance spectra are used to infer the coordinating capacity of the ligand and the geometrical structure of these complexes are found to be octahedral. The thermal behaviour of these chelates shows that the hydrated water molecules and the anions are removed in a successive two steps followed immediately by decomposition of the ligands (L(1), L(2) and L') in the subsequent steps. The activation thermodynamic parameters, such as, E*, DeltaH*, DeltaS* and DeltaG* are calculated from the TG curves and discussed. The ligands and their metal chelates have been screened for their antimicrobial activities and the findings have been reported, explained and compared with some known antibiotics. PMID:15741103

  8. Synthesis of heterocycles: Indolo (2,1-a) isoquinolines, renewables, and aptamer ligands for cellular imaging

    SciTech Connect

    Beasley, Jonathan

    2013-01-01

    In this thesis, we explore both total syntheses and methodologies of several aromatic heterocyclic molecules. Extensions of the Kraus indole synthesis toward 2-substituted and 2,3-disubstituted indoles, as well as biologically attractive indolo[2,1-a]isoquinolines are described. Recent renewable efforts directed to commodity maleic acid and the first reported furan-based ionic liquids are described. Our total synthesis of mRNA aptamer ligand PDC-Gly, and its dye coupled forms, plus aminoglycoside dye coupled ligands used in molecular imaging, are described.

  9. Kinetic and spectral properties of isovaleryl-CoA dehydrogenase and interaction with ligands.

    PubMed

    Mohsen, Al-Walid A; Vockley, Jerry

    2015-01-01

    Isovaleryl-CoA dehydrogenase (IVD) catalyzes the conversion of isovaleryl-CoA to 3-methylcrotonyl-CoA and the transfer of electrons to the electron transfer flavoprotein (ETF). Recombinant human IVD purifies with bound CoA-persulfide. A modified purification protocol was developed to isolate IVD without bound CoA-persulfide and to protect the protein thiols from oxidation. The CoA-persulfide-free IVD specific activity was 112.5 μmol porcine ETF min(-)(1) mg(-)(1), which was ∼20-fold higher than that of its CoA-persulfide bound form. The Km and catalytic efficiency (kcat/Km) for isovaleryl-CoA were 1.0 μM and 4.3 × 10(6) M(-1) s(-1) per monomer, respectively, and its Km for ETF was 2.0 μM. Anaerobic titration of isovaleryl-CoA into an IVD solution resulted in a stable blue complex with increased absorbance at 310 nm, decreased absorbance at 373 and 447 nm, and the appearance of the charge transfer complex band at 584 nm. The apparent dissociation constant (KDapp) determined spectrally for isovaleryl-CoA was 0.54 μM. Isovaleryl-CoA, acetoacetyl-CoA, methylenecyclopropyl-acetyl-CoA, and ETF induced CD spectral changes at the 250-500 nm region while isobutyryl-CoA did not, suggesting conformational changes occur at the flavin ring that are ligand specific. Replacement of the IVD Trp166 with a Phe did not block IVD interaction with ETF, indicating that its indole ring is not essential for electron transfer to ETF. A twelve amino acid synthetic peptide that matches the sequence of the ETF docking peptide competitively inhibited the enzyme reaction when ETF was used as the electron acceptor with a Ki of 1.5 mM. PMID:25450250

  10. Kinetic and Spectral Properties of Isovaleryl-CoA Dehydrogenase and Interaction with Ligands

    PubMed Central

    Mohsen, Al-Walid A.; Vockley, Jerry

    2014-01-01

    Isovaleryl-CoA dehydrogenase (IVD) catalyzes the conversion of isovaleryl-CoA to 3-methylcrotonyl-CoA and the transfer of electrons to the electron transfer flavoprotein (ETF). Recombinant human IVD purifies with bound CoA-persulfide. A modified purification protocol was developed to isolate IVD without bound CoA-persulfide and to protect the protein thiols from oxidation. The CoA-persulfide-free IVD specific activity was 112.5 µmol porcine ETF•min−1•mg−1, which was ~20-fold higher than that of its CoA-persulfide bound form. The Km and catalytic efficiency (kcat/Km) for isovaleryl-CoA were 1.0 µM and 4.3 × 106•M−1•sec−1 per monomer, respectively, and its Km for ETF was 2.0 µM. Anaerobic titration of isovaleryl-CoA into an IVD solution resulted in a stable blue complex with increased absorbance at 310 nm, decreased absorbance at 373 and 447 nm, and the appearance of the charge transfer complex band at 584 nm. The apparent dissociation constant (KD app) determined spectrally for isovaleryl-CoA was 0.54 µM. Isovaleryl-CoA, acetoacetyl-CoA, methylenecyclopropylacetyl-CoA, and ETF induced CD spectral changes at the 250–500 nm region while isobutyryl-CoA did not, suggesting conformational changes occur at the flavin ring that are ligand specific. Replacement of the IVD Trp166 with a Phe did not block IVD interaction with ETF, indicating that its indole ring is not essential for electron transfer to ETF. A twelve amino acid synthetic peptide that matches the sequence of the ETF docking peptide competitively inhibited the enzyme reaction when ETF was used as the electron acceptor with a Ki of 1.5 mM. PMID:25450250

  11. MIUSCAT: extended MILES spectral coverage - I. Stellar population synthesis models

    NASA Astrophysics Data System (ADS)

    Vazdekis, A.; Ricciardelli, E.; Cenarro, A. J.; Rivero-González, J. G.; Díaz-García, L. A.; Falcón-Barroso, J.

    2012-07-01

    We extend the spectral range of our stellar population synthesis models based on the MILES and CaT empirical stellar spectral libraries. For this purpose, we combine these two libraries with the Indo-U.S. to construct composite stellar spectra to feed our models. The spectral energy distributions (SEDs) computed with these models and the originally published models are combined to construct composite SEDs for single-age, single-metallicity stellar populations (SSPs) covering the range λλ3465-9469 Å at moderately high and uniform resolution (full width at half-maximum = 2.51 Å). The colours derived from these SSP SEDs provide good fits to Galactic globular cluster data. We find that the colours involving redder filters are very sensitive to the initial mass function (IMF), as well as a number of features and molecular bands throughout the spectra. To illustrate the potential use of these models, we focus on the Na I doublet at 8200 Å and with the aid of the newly synthesized SSP model SEDs, we define a new IMF-sensitive index that is based on this feature, which overcomes various limitations from previous index definitions for low-velocity dispersion stellar systems. We propose an index-index diagram based on this feature and the neighbouring Ca II triplet at 8600 Å, to constrain the IMF if the age and [Na/Fe] abundance are known. Finally we also show a survey-oriented spectrophotometric application which evidences the accurate flux calibration of these models for carrying out reliable spectral fitting techniques. These models are available through our user-friendly website.

  12. Synthesis, spectroscopic and thermal studies of some IIB group complexes with a new N 2-Schiff base ligand

    NASA Astrophysics Data System (ADS)

    Montazerozohori, Morteza; Khani, Sara; Tavakol, Hosein; Hojjati, Ahmad; Kazemi, Mostafa

    2011-10-01

    Synthesis, spectroscopic and thermal studies of some complexes of a new N 2-Schiff base ligand of N1, N2-bis((E)-2-methyl-3-phenylallylidene)ethane-1,2-diamine (L) with a general formula of MLX 2 (M = Zn(II), Cd(II) and Hg(II); X = Cl -, Br -, I -, SCN - and N 3-) are described. The ligand and its complexes were characterized by elemental analysis, molar conductance, UV-vis spectra, FT-IR spectra, MS, 1H NMR and 13C NMR spectra. The conductivity measurement as well as spectral data indicated that the complexes are non-electrolyte. 1H and 13C NMR spectra have been studied in DMSO-d 6 and/or CDCl 3. The thermal behavior of the complexes shows weight loss by decomposition of the anions and ligand segments in the subsequent steps. Activation thermodynamic parameters of decomposition such as E*, Δ H*, Δ S* and Δ G* were calculated from TG curves.

  13. Spectral studies of cobalt(II) complexes of 12-membered macrocyclic ligands having thiosemicarbazone moieties

    NASA Astrophysics Data System (ADS)

    Chandra, Sulekh; Pundir, Meenakshi

    2007-11-01

    Cobalt(II) complexes of general composition [Co(L)X 2] and [Co(L 1)X 2] where (X = NO 3-, CH 3COO -, Cl -, Br -, NCS -, (1/2)SO 4-2); L = 5,11-diethyl-6,12-dimethyl-3,8-dithione-1,2,4,7,9,10-hexaaza cyclododeca-1,4,6,10-tetraene and L 1 = 5,11-diethyl-6,12-dimethyl-3,8-dione-1,2,4,7,9,10-hexaaza cyclododeca-1,4,6,10-tetraene with tetradentate 12-membered macrocyclic ligands have been synthesized and characterized by elemental analysis, magnetic susceptibility, IR, electronic and electon spin resonance spectral studies. The various physico-chemical techniques suggest a coordination number six (octahedral geometry) for chloro, nitrato, bromo and thiocyanato complexes, and five-coordinated trigonal bipyramidal geometry for sulphato complexes. All the complexes are of high spin type showing magnetic moment corresponding to three unpaired electrons. All the complexes were also screened against bacteria and pathogenic fungi in vitro.

  14. Synthesis, Spectral, and In Vitro Antibacterial Studies of Organosilicon(IV) Complexes with Schiff Bases Derived from Amino Acids

    PubMed Central

    Singh, Har Lal; Singh, Jangbhadur; Mukherjee, A.

    2013-01-01

    The present work stems from our interest in the synthesis, characterization, and antibacterial evaluation of organosilicon(IV) complexes of a class of amino-acid-based Schiff base which have been prepared by the interaction of ethoxytrimethylsilane with the Schiff bases (N OH) in 1 : 1 molar ratio. These complexes have been characterized by elemental analysis, molar conductance, and spectroscopic studies including electronic IR and NMR (1H, 13C, and 29Si) spectroscopy. The analytical and spectral data suggest trigonal bipyramidal geometry around the silicon atom in the resulting complexes. The ligands and their organosilicon complexes have also been evaluated for in vitro antimicrobial activity against bacteria (Bacillus cereus, Nocardia spp., E. aerogenes, Escherichia coli, Klebsiella spp., and Staphylococcus spp.). The complexes were found to be more potent as compared to the ligands. PMID:23983671

  15. Synthesis and Characterization of Metal Complexes with Schiff Base Ligands

    ERIC Educational Resources Information Center

    Wilkinson, Shane M.; Sheedy, Timothy M.; New, Elizabeth J.

    2016-01-01

    In order for undergraduate laboratory experiments to reflect modern research practice, it is essential that they include a range of elements, and that synthetic tasks are accompanied by characterization and analysis. This intermediate general chemistry laboratory exercise runs over 2 weeks, and involves the preparation of a Schiff base ligand and…

  16. Synthesis, characterization and crystal structure of some bidentate heterocyclic Schiff base ligands of 4-toluoyl pyrazolones and its mononuclear Cu(II) complexes

    NASA Astrophysics Data System (ADS)

    Vyas, Komal M.; Jadeja, R. N.; Gupta, Vivek K.; Surati, K. R.

    2011-03-01

    We depict the synthesis of a new set of six bidentate heterocyclic Schiff base ligands, formed by the condensation of three different 4-toluoyl pyrazolones with various aromatic amines in ethanolic medium. All of these ligands have been characterized on the basis of elemental analysis, IR, 1H NMR, 13C NMR and Mass spectral data. The molecular geometries of three of these ligands have been determined by single crystal X-ray study. It reveals that these ligands exist in amine-one tautomeric form in the solid state. The reaction of these ligands with copper(II) resulted in the formation of mononuclear complexes having the general composition [CuL 2(H 2O) 2] with two water molecules at axial positions. These complexes have been characterized on the basis of elemental analysis, Cu-estimation, molar conductivity, magnetic measurements, IR, UV-Visible, FAB-Mass, TG-DTA-DSC data, cyclic voltametric measurements and ESR spectral studies. ESR spectra and magnetic susceptibility measurements indicates distorted octahedral stereochemistry of Cu(II) complexes, while non-electrolytic behaviour of complexes indicates the absence of counter ion.

  17. Assembling ligands in situ using bioorthogonal boronate ester synthesis

    PubMed Central

    Shin, Sung Bin Y.; Almeida, Ramiro; Gerona-Navarro, Guillermo; Bracken, Clay; Jaffrey, Samie R.

    2011-01-01

    SUMMARY Many molecules that could manipulate cellular function are not practical due to their large size and concomitant undesirable pharmocokinetic properties. Here we describe a bioorthogonal, highly stable boronate ester (HiSBE) synthesis and use this reaction to synthesize a bioogically active molecule from smaller precursors in a physiological context. The rapid rate of HiSBE synthesis suggests that it may be useful for assembling a wide variety of biologically active molecules in physiological solutions. PMID:21095566

  18. Rational design, synthesis, and verification of affinity ligands to a protein surface cleft

    PubMed Central

    Baumann, Herbert; Öhrman, Sara; Shinohara, Yasuro; Ersoy, Oguz; Choudhury, Devapriya; Axén, Andreas; Tedebark, Ulf; Carredano, Enrique

    2003-01-01

    The structure-based design, synthesis, and screening of a glucuronic acid scaffold library of affinity ligands directed toward the catalytic cleft on porcine pancreas α-amylase are presented. The design was based on the simulated docking to the enzyme active site of 53 aryl glycosides from the Available Chemicals Directory (ACD) selected by in silico screening. Twenty-three compounds were selected for synthesis and screened in solution for binding toward α-amylase using nuclear magnetic resonance techniques. The designed molecules include a handle outside of the binding site to allow their attachment to various surfaces with minimal loss of binding activity. After initial screening in solution, one affinity ligand was selected, immobilized to Sepharose (Amersham Biosciences), and evaluated as a chromatographic probe. A column packed with ligand-coupled Sepharose specifically retained the enzyme, which could be eluted by a known inhibitor. PMID:12649437

  19. Spectral models for musical sound synthesis: Expression issues

    NASA Astrophysics Data System (ADS)

    Serra, Xavier

    2002-05-01

    In order to obtain a naturally sounding musical instrument or voice, we require sound models that can both capture the microstructure characteristics of the acoustical source and that at the same time can be controlled by meaningful parameters, in a similar way as the performers do. The issue of how to generate these control parameters is one of the most interesting and open problems in the area of musical sound synthesis. This presentation will focus on the control question in the context of two recently developed synthesizers based on a spectral modeling approach: a singing voice synthesizer and a wind instrument synthesizer. The specific spectral models used in each case will be presented followed by a discussion on the expression controls employed and how they are obtained from actual performances. These controls are mainly at the note and the note-to-note articulation level and affect parameters such as pitch, dynamics, brightness, and vibrato. From actual performances, templates and models of the temporal evolution of these parameters are extracted and then used as the basic controls of the synthesizer on top of which the user interacts in real time.

  20. Silver, Gold, Palladium Nanoparticles: Ligand Design, Synthesis and Polymer Composites

    NASA Astrophysics Data System (ADS)

    Iqbal, Muhammad

    Metal nanoparticles, especially gold nanoparticles (AuNPs), have been extensively studied due to their interesting optical properties and potential applications in emerging technologies like drug delivery, cancer therapy, catalysis, chemical and bio-sensing and microelectronics devices. Alkyl thiol ligands in the form of self assembled monolayers are often used to stabilize and functionalize the gold nanoparticles while other types of ligands have been rarely employed and the properties of AuNPs protected by different types of ligands have not been studied comprehensively and comparatively. This dissertation reports the first comparative studies on the thermal and chemical stability of AuNPs protected by alkyl thiolates, alkyl selenolates, dialkyl dithiophosphinates, and dialkyl dithiophosphates (Chapters 2 and 3). AuNPs protected by dialkyl dithiophosphinates and dialkyl dithiophosphates are unprecedented. All AuNPs were prepared from amine protected precursor AuNPs by ligand exchange to ensure similar size, size distribution, and chemical composition. They were extensively characterized by solution 1H-NMR and UV-VIS spectroscopy, transmission electron microscopy (TEM), thermal analysis, X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) analysis. For the first time, thermal stability was investigated by differential scanning calorimetry (DSC) that provided more accurate decomposition temperatures and enthalpies, whereas chemical stability was tested as the availability of the gold surface towards etching with cyanide in different solvents. Surprisingly, alkyl selenolate protected AuNPs are thermally less stable than alkyl thiolate protected AuNPs despite their proposed stronger binding to the gold surface and a much more crystalline monolayer, which suggests that different decomposition mechanisms apply to alkyl thiolate and alkyl selenolate protected AuNPs. Dialkyl dithiophosphinates and dialkyl dithiophosphates protected AuNPs are thermally

  1. Design, synthesis and biological studies of efficient multivalent melanotropin ligands: tools towards melanoma diagnosis and treatment

    PubMed Central

    Brabez, Nabila; Lynch, Ronald M.; Xu, Liping; Gillies, Robert J.; Chassaing, Gerard; Lavielle, Solange; Hruby, Victor J.

    2011-01-01

    In order to achieve early detection and specific cancer treatment we propose the use of multivalent interactions in which a series of binding events leads to increased affinity and consequently to selectivity. Using melanotropin (MSH) ligands, our aim is to target melanoma cells, which overexpress melanocortin receptors. In this study, we report the design and efficient synthesis of new trivalent ligands bearing MSH ligands. Evaluation of these multimers on a cell model engineered to overexpress melanocortin 4 receptors (MC4R) showed up to a 350-fold increase in binding compared to the monomer, resulting in a trivalent construct with nanomolar affinity starting from a micromolar affinity ligand. Cyclic adenosine monophosphate (cAMP) production was also investigated leading to more insights into the effects of multivalent compounds on transduction mechanisms. PMID:21928837

  2. New 15-membered tetraaza (N4) macrocyclic ligand and its transition metal complexes: Spectral, magnetic, thermal and anticancer activity

    NASA Astrophysics Data System (ADS)

    El-Boraey, Hanaa A.; EL-Gammal, Ohyla A.

    2015-03-01

    Novel tetraamidemacrocyclic 15-membered ligand [L] i.e. naphthyl-dibenzo[1,5,9,12]tetraazacyclopentadecine-6,10,11,15-tetraoneand its transition metal complexes with Fe(II), Co(II), Ni(II), Cu(II), Ru(III) and Pd(II) have been synthesized and characterized by elemental analysis, spectral, thermal as well as magnetic and molar conductivity measurements. On the basis of analytical, spectral (IR, MS, UV-Vis, 1H NMR and EPR) and thermal studies distorted octahedral or square planar geometry has been proposed for the complexes. The antitumor activity of the synthesized ligand and some complexes against human breast cancer cell lines (MCF-7) and human hepatocarcinoma cell lines (HepG2) has been studied. The complexes (IC50 = 2.27-2.7, 8.33-31.1 μg/mL, respectively) showed potent antitumor activity, towards the former cell lines comparable with their ligand (IC50 = 13, 26 μg/mL, respectively). The results show that the activity of the ligand towards breast cancer cell line becomes more pronounced and significant when coordinated to the metal ion.

  3. Preparation, spectral and biological investigation of formaldehyde-based ligand containing piperazine moiety and its various polymer metal complexes

    NASA Astrophysics Data System (ADS)

    Khan, Shamim Ahmad; Nishat, Nahid; Parveen, Shadma; Rasool, Raza

    2011-10-01

    A novel tetradentate salicylic acid-formaldehyde ligand containing piperazine moiety (SFP) was synthesized by condensation of salicylic acid, formaldehyde and piperazine in presence of base catalyst, which was subjected for the preparation of coordination polymers with metal ions like manganese(II), cobalt(II), copper(II), nickel(II) and zinc(II). All the synthesized polymeric compounds were characterized by elemental analysis, IR, 1H NMR and electronic spectral studies. The thermal stability was determined by thermogravimetric analysis and thermal data revealed that all the polymer metal complexes show good thermal stability than their parent ligand. Electronic spectral data and magnetic moment values revealed that polymer metal complexes of Mn(II), Co(II) and Ni(II) show an octahedral geometry while Cu(II) and Zn(II) show distorted octahedral and tetrahedral geometry respectively. The antimicrobial screening of the ligand and coordination polymers was done by using Agar well diffusion method against various bacteria and fungi. It was evident from the data that antibacterial and antifungal activity increased on chelation and all the polymer metal complexes show excellent antimicrobial activity than their parent ligand.

  4. Preparation, spectral and biological investigation of formaldehyde-based ligand containing piperazine moiety and its various polymer metal complexes.

    PubMed

    Khan, Shamim Ahmad; Nishat, Nahid; Parveen, Shadma; Rasool, Raza

    2011-10-15

    A novel tetradentate salicylic acid-formaldehyde ligand containing piperazine moiety (SFP) was synthesized by condensation of salicylic acid, formaldehyde and piperazine in presence of base catalyst, which was subjected for the preparation of coordination polymers with metal ions like manganese(II), cobalt(II), copper(II), nickel(II) and zinc(II). All the synthesized polymeric compounds were characterized by elemental analysis, IR, (1)H NMR and electronic spectral studies. The thermal stability was determined by thermogravimetric analysis and thermal data revealed that all the polymer metal complexes show good thermal stability than their parent ligand. Electronic spectral data and magnetic moment values revealed that polymer metal complexes of Mn(II), Co(II) and Ni(II) show an octahedral geometry while Cu(II) and Zn(II) show distorted octahedral and tetrahedral geometry respectively. The antimicrobial screening of the ligand and coordination polymers was done by using Agar well diffusion method against various bacteria and fungi. It was evident from the data that antibacterial and antifungal activity increased on chelation and all the polymer metal complexes show excellent antimicrobial activity than their parent ligand. PMID:21757398

  5. Transition metal complexes of a new 15-membered [N5] penta-azamacrocyclic ligand with their spectral and anticancer studies

    NASA Astrophysics Data System (ADS)

    El-Boraey, Hanaa A.; Serag El-Din, Azza A.

    2014-11-01

    Novel penta-azamacrocyclic 15-membered [N5] ligand [L] i.e. 1,5,8,12-tetetraaza-3,4: 9,10-dibenzo-6-ethyl-7-methyl-1,12-(2,6-pyrido)cyclopentadecan-5,7 diene-2,11-dione and its transition metal complexes with Co(II), Ni(II), Cu(II), Ru(III) and Pd(II) have been synthesized and structurally characterized by elemental analysis, spectral, thermal as well as magnetic and molar conductivity measurements. On basis of IR, MS, UV-Vis 1H NMR and EPR spectral studies an octahedral geometry has been proposed for all complexes except Co(II), Cu(II) nitrate complexes and Pd(II) chloride complex that adopt tetrahedral, square pyramidal and square planar geometries, respectively. The antitumor activity of the synthesized ligand and some complexes against human breast cancer cell lines (MCF-7) and human hepatocarcinoma cell lines (HepG2) has been studied. The complexes (IC50 = 2.04-9.7, 2.5-3.7 μg/mL) showed potent antitumor activity comparable with their ligand (IC50 = 11.7, 3.45 μg/mL) against the above mentioned cell lines, respectively. The results evidently show that the activity of the ligand becomes more pronounced and significant when coordinated to the metal ion.

  6. Transition metal complexes of a new 15-membered [N5] penta-azamacrocyclic ligand with their spectral and anticancer studies.

    PubMed

    El-Boraey, Hanaa A; Serag El-Din, Azza A

    2014-11-11

    Novel penta-azamacrocyclic 15-membered [N5] ligand [L] i.e. 1,5,8,12-tetetraaza-3,4: 9,10-dibenzo-6-ethyl-7-methyl-1,12-(2,6-pyrido)cyclopentadecan-5,7 diene-2,11-dione and its transition metal complexes with Co(II), Ni(II), Cu(II), Ru(III) and Pd(II) have been synthesized and structurally characterized by elemental analysis, spectral, thermal as well as magnetic and molar conductivity measurements. On basis of IR, MS, UV-Vis 1H NMR and EPR spectral studies an octahedral geometry has been proposed for all complexes except Co(II), Cu(II) nitrate complexes and Pd(II) chloride complex that adopt tetrahedral, square pyramidal and square planar geometries, respectively. The antitumor activity of the synthesized ligand and some complexes against human breast cancer cell lines (MCF-7) and human hepatocarcinoma cell lines (HepG2) has been studied. The complexes (IC50=2.04-9.7, 2.5-3.7 μg/mL) showed potent antitumor activity comparable with their ligand (IC50=11.7, 3.45 μg/mL) against the above mentioned cell lines, respectively. The results evidently show that the activity of the ligand becomes more pronounced and significant when coordinated to the metal ion. PMID:24892547

  7. Efficient synthesis of hexahydroindenopyridines and their potential as melatoninergic ligands.

    PubMed

    Párraga, Javier; Moreno, Laura; Diaz, Amelia; El Aouad, Noureddine; Galán, Abraham; Sanz, María Jesús; Caignard, Daniel-Henri; Figadère, Bruno; Cabedo, Nuria; Cortes, Diego

    2014-10-30

    Hexahydroindenopyridine (HHIP) is an interesting tricyclic piperidine nucleus that is structurally related to melatonin, a serotonin-derived neurohormone. Melatonin receptor ligands have applications in several cellular, neuroendocrine and neurophysiological disorders, including depression and/or insomnia. We report herein an efficient two-step method to prepare new HHIP via enamine C-alkylation-cyclization. The influence of substituents on the benzene ring and the nitrogen atom on melatoninergic receptors has been studied. Among the 25 synthesized HHIPs, some of them containing methylenedioxy (series 2) and 8-chloro-7-methoxy substituents (series 4) on the benzene ring revealed affinity for the MT1 and/or the MT2 receptors within the nanomolar range or low micromolar. Similar activities were also encountered for those presenting urea (4g), N-aryl (2e) and N-alkyl (2f) acetamide functions. Therefore, new synthesized compounds with a HHIP nucleus have emerged as new promising leads towards the discovery of melatoninergic ligands which could provide new therapeutic agents. PMID:25232966

  8. Multi-tasking Schiff base ligand: a new concept of AuNPs synthesis.

    PubMed

    Abad, Jose Maria; Bravo, Iria; Pariente, Felix; Lorenzo, Encarnación

    2016-03-01

    Multi-tasking 3,4-dihydroxysalophen Schiff base tetradentate ligand (3,4-DHS) as reductant, stabilizer, and catalyst in a new concept of gold nanoparticles (AuNPs) synthesis is demonstrated. 3,4-DHS is able to reduce HAuCl4 in water, acting also as capping agent for the generation of stable colloidal suspensions of Schiff base ligand-AuNPs assemblies of controlled size by providing a robust coating to AuNPs, within a unique reaction step. Once deposited on carbon electrodes, 3,4-DHS-AuNPs assemblies show a potent electrocatalytic effect towards hydrazine oxidation and hydrogen peroxide oxidation/reduction. PMID:26922338

  9. Synthesis, spectral, computational and thermal analysis studies of metallocefotaxime antibiotics.

    PubMed

    Masoud, Mamdouh S; Ali, Alaa E; Elasala, Gehan S

    2015-10-01

    Cefotaxime metal complexes of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Hg(II) and two mixed metals complexes of (Fe,Cu) and (Fe,Ni) were synthesized and characterized by elemental analysis, IR, electronic spectra, magnetic susceptibility and ESR spectra. The studies proved that cefotaxime may act as mono, bi, tri and tetra-dentate ligand through oxygen atoms of lactam carbonyl, carboxylic or amide carbonyl groups and nitrogen atom of thiazole ring. From the magnetic measurements and electronic spectral data, octahedral structures were proposed for all complexes. Quantum chemical methods have been performed for cefotaxime to calculate charges, bond lengths, bond angles, dihedral angles, electronegativity (χ), chemical potential (μ), global hardness (η), softness (σ) and the electrophilicity index (ω). The thermal decomposition of the prepared metals complexes was studied by TGA, DTA and DSC techniques. Thermogravimetric studies revealed the presence of lattice or coordinated water molecules in all the prepared complexes. The decomposition mechanisms were suggested. The thermal decomposition of the complexes ended with the formation of metal oxides and carbon residue as a final product except in case of Hg complex, sublimation occur at the temperature range 376.5-575.0 °C so, only carbon residue was produced during thermal decomposition. The orders of chemical reactions (n) were calculated via the peak symmetry method and the activation parameters were computed from the thermal decomposition data. The geometries of complexes may be converted from Oh to Td during the thermal decomposition steps. PMID:25974669

  10. Ruthenium(II) complexes containing quinone based ligands: Synthesis, characterization, catalytic applications and DNA interaction

    NASA Astrophysics Data System (ADS)

    Anitha, P.; Manikandan, R.; Endo, A.; Hashimoto, T.; Viswanathamurthi, P.

    2012-12-01

    1,2-Naphthaquinone reacts with amines such as semicarbazide, isonicotinylhydrazide and thiosemicarbazide in high yield procedure with the formation of tridentate ligands HLn (n = 1-3). By reaction of ruthenium(II) starting complexes and quinone based ligands HLn (n = 1-3), a series of ruthenium complexes were synthesized and characterized by elemental and spectroscopic methods (FT-IR, electronic, 1H, 13C, 31P NMR and ESI-MS). The ligands were coordinated to ruthenium through quinone oxygen, imine nitrogen and enolate oxygen/thiolato sulfur. On the basis of spectral studies an octahedral geometry may be assigned for all the complexes. Further, the catalytic oxidation of primary, secondary alcohol and transfer hydrogenation of ketone was carried out. The DNA cleavage efficiency of new complexes has also been tested.

  11. Synthesis and estrogen receptor affinity of a 4-hydroxytamoxifen-labeled ligand for diagnostic imaging.

    PubMed

    Lashley, Matthew R; Niedzinski, Edmund J; Rogers, Jane M; Denison, Michael S; Nantz, Michael H

    2002-12-01

    A 10-step synthesis of a novel 4-hydroxytamoxifen-DTPA ligand (HOTam-DTPA) is reported. Tamoxifen and its primary metabolite 4-hydroxytamoxifen are common estrogen receptor ligands. Consequently, tamoxifen has found utility as the targeting component of various diagnostic agents for selective imaging of estrogen receptor-rich tissue, specifically breast cancer. An L-aspartic acid-derived DTPA analogue was attached to the ethyl side chain of 4-hydroxy-tamoxifen using N,N'-dimethylethylenediamine as a hydrophilic linker. A competitve estrogen receptor binding assay using [3H]-17beta-estradiol was performed to determine the effect of the ethyl side chain modification on estrogen receptor affinity. The results show that while the relative affinity of HOTam-DTPA for the estrogen receptor is approximately 10-fold lower than that of tamoxifen, it still remains a potent ligand at relatively low concentrations. PMID:12413861

  12. Design, Synthesis, and Structure–Activity Relationships of Highly Potent 5-HT3 Receptor Ligands

    PubMed Central

    2012-01-01

    The 5-HT3 receptor, a pentameric ligand-gated ion channel (pLGIC), is an important therapeutic target. During a recent fragment screen, 6-chloro-N-methyl-2-(4-methyl-1,4-diazepan-1-yl)quinazolin-4-amine (1) was identified as a 5-HT3R hit fragment. Here we describe the synthesis and structure–activity relationships (SAR) of a series of (iso)quinoline and quinazoline compounds that were synthesized and screened for 5-HT3R affinity using a [3H]granisetron displacement assay. These studies resulted in the discovery of several high affinity ligands of which compound 22 showed the highest affinity (pKi > 10) for the 5-HT3 receptor. The observed SAR is in agreement with established pharmacophore models for 5-HT3 ligands and is used for ligand–receptor binding mode prediction using homology modeling and in silico docking approaches. PMID:23006041

  13. Zinc acetylacetonate hydrate adducted with nitrogen donor ligands: Synthesis, spectroscopic characterization, and thermal analysis

    NASA Astrophysics Data System (ADS)

    Brahma, Sanjaya; Shivashankar, S. A.

    2015-12-01

    We report synthesis, spectroscopic characterization, and thermal analysis of zinc acetylacetonate complex adducted by nitrogen donor ligands, such as pyridine, bipyridine, and phenanthroline. The pyridine adducted complex crystallizes to monoclinic crystal structure, whereas other two adducted complexes have orthorhombic structure. Addition of nitrogen donor ligands enhances the thermal property of these complexes as that with parent metal-organic complex. Zinc acetylacetonate adducted with pyridine shows much higher volatility (106 °C), decomposition temperature (202 °C) as that with zinc acetylacetonate (136 °C, 220 °C), and other adducted complexes. All the adducted complexes are thermally stable, highly volatile and are considered to be suitable precursors for metal organic chemical vapor deposition. The formation of these complexes is confirmed by powder X-ray diffraction, Fourier transform infrared spectroscopy, mass spectroscopy, and elemental analysis. The complexes are widely used as starting precursor materials for the synthesis of ZnO nanostructures by microwave irradiation assisted coating process.

  14. Ligands for FKBP12 Increase Ca2+ Influx and Protein Synthesis to Improve Skeletal Muscle Function*

    PubMed Central

    Lee, Chang Seok; Georgiou, Dimitra K.; Dagnino-Acosta, Adan; Xu, Jianjun; Ismailov, Iskander I.; Knoblauch, Mark; Monroe, Tanner O.; Ji, RuiRui; Hanna, Amy D.; Joshi, Aditya D.; Long, Cheng; Oakes, Joshua; Tran, Ted; Corona, Benjamin T.; Lorca, Sabina; Ingalls, Christopher P.; Narkar, Vihang A.; Lanner, Johanna T.; Bayle, J. Henri; Durham, William J.; Hamilton, Susan L.

    2014-01-01

    Rapamycin at high doses (2–10 mg/kg body weight) inhibits mammalian target of rapamycin complex 1 (mTORC1) and protein synthesis in mice. In contrast, low doses of rapamycin (10 μg/kg) increase mTORC1 activity and protein synthesis in skeletal muscle. Similar changes are found with SLF (synthetic ligand for FKBP12, which does not inhibit mTORC1) and in mice with a skeletal muscle-specific FKBP12 deficiency. These interventions also increase Ca2+ influx to enhance refilling of sarcoplasmic reticulum Ca2+ stores, slow muscle fatigue, and increase running endurance without negatively impacting cardiac function. FKBP12 deficiency or longer treatments with low dose rapamycin or SLF increase the percentage of type I fibers, further adding to fatigue resistance. We demonstrate that FKBP12 and its ligands impact multiple aspects of muscle function. PMID:25053409

  15. One-Pot Copper(I)-Catalyzed Ligand/Base-Free Tandem Cyclooxidative Synthesis of Quinazolinones.

    PubMed

    Upadhyaya, Kapil; Thakur, Ravi Kumar; Shukla, Sanjeev K; Tripathi, Rama Pati

    2016-06-17

    A novel and efficient Cu(I)-catalyzed ligand- and base-free multipathway domino strategy has been developed for the synthesis of 2-substituted quinazolinones. The reaction utilizes 2-bromobenzamide and multiform substrates such as aldehydes, alcohols, and methyl arenes for a one-pot protocol, whereas TMSN3 is used as a nitrogen source. A wide range of substrate scope, functional group tolerance, and operational simplicity are synthetically useful features. PMID:27223462

  16. The synthesis of symmetrical bis-1,2,5-thiadiazole ligands.

    SciTech Connect

    Mullins, Michael J.; Abboud, Khalil A.; Philipp, Dean M.; Muller, Richard Partain; Goddard, William A., III; Athey, Phillip S.; Snelgrove, R. Vernon

    2004-05-01

    We have been engaged in a search for coordination catalysts for the copolymerization of polar monomers (such as vinyl chloride and vinyl acetate) with ethylene. We have been investigating complexes of late transition metals with heterocyclic ligands. In this report we describe the synthesis of a symmetrical bis-thiadiazole. We have characterized one of the intermediates using single crystal X-ray diffraction. Several unsuccessful approaches toward 1 are also described, which shed light on some of the unique chemistry of thiadiazoles.

  17. Synthesis of Phthalimide Derivatives as Potential PPAR-γ Ligands

    PubMed Central

    Eom, So Hyeon; Liu, Sen; Su, Mingzhi; Noh, Tae Hwan; Hong, Jongki; Kim, Nam Deuk; Chung, Hae Young; Yang, Min Hye; Jung, Jee H.

    2016-01-01

    Paecilocin A, a phthalide derivative isolated from the jellyfish-derived fungus Paecilomyces variotii, activates PPAR-γ (Peroxisome proliferator-activated receptor gamma) in rat liver Ac2F cells. Based on a SAR (Structure-activity relationships) study and in silico analysis of paecilocin A-mimetic derivatives, additional N-substituted phthalimide derivatives were synthesized and evaluated for PPAR-γ agonistic activity in both murine liver Ac2F cells and in human liver HepG2 cells by luciferase assay, and for adipogenic activity in 3T3-L1 cells. Docking simulation indicated PD6 was likely to bind most strongly to the ligand binding domain of PPAR-γ by establishing crucial H-bonds with key amino acid residues. However, in in vitro assays, PD1 and PD2 consistently displayed significant PPAR-γ activation in Ac2F and HepG2 cells, and adipogenic activity in 3T3-L1 preadipocytes. PMID:27338418

  18. Synthesis, Characterization, and Reactivity Studies of Iron Complexes Supported by the Redox-Active [ONO] Ligand

    NASA Astrophysics Data System (ADS)

    Wong, Janice Lin

    The work reported herein primarily focuses on the development of new platforms for multi-electron reactivity using iron complexes supported by a redox-active pincer-type ligand. This dissertation details the synthesis, characterization, and reactivity of iron complexes coordinated to the redox-active [ONO] ([ONO]H3 = bis(3,5-di-tert-butyl-2-phenol)amine) ligand. Chapter 1 provides a general background on ligand-centered and metal-centered redox reactivity. Specifically, the characteristics of redox-active ligands and their ability to promote multi-electron reactivity at redox-inert metal centers is presented. In addition, iron-catalyzed organic transformations in which the metal center undergoes redox changes is also discussed. Finally, ligand-enabled redox reactions mediated by iron complexes containing redox-active ligands is described. Chapter 2 reports on the complexation of bis(3,5-di-tert-butyl-2-phenoxy)amine, [ONHO], and the redox-active [ONO] ligands by iron centers to afford a new family of iron complexes. Characterizations of each compound through a battery of analytical techniques reveal the oxidation states of the metal center and ligand. Furthermore, the electronic properties of each complex were investigated in order to evaluate their potential to facilitate multi-electron reactivity. Chapter 3 details the reactivity of the [ONO]Fe platform. Metathesis reactions are conducted with [ONOq]FeIIIX 2 (X = Cl, N[SiMe3]2) complexes, demonstrating the capability of the fully-oxidized [ONOq]1-- to act as a two-electron acceptor to generate the fully reduced [ONO cat]3-- that is coordinated to an iron(III) center. Similarly, oxidation of [ONOcat]FeIII(py) 3 (py = pyridine) using dihalogens result in two-electron oxidations of the tridentate ligand while the metal oxidation state remains the same. These redox reactions showcase the ability of the [ONO] ligand platform to undergo reversible two-electron oxidation state changes, allowing multi-electron reactivity

  19. Photochemical Synthesis and Ligand Exchange Reactions of Ru(CO)[subscript 4] (Eta[superscript 2]-Alkene) Compounds

    ERIC Educational Resources Information Center

    Cooke, Jason; Berry, David E.; Fawkes, Kelli L.

    2007-01-01

    The photochemical synthesis and subsequent ligand exchange reactions of Ru(CO)[subscript 4] (eta[superscript2]-alkene) compounds has provided a novel experiment for upper-level inorganic chemistry laboratory courses. The experiment is designed to provide a system in which the changing electronic properties of the alkene ligands could be easily…

  20. In situ synthesis of stable mixed ligand Fe2+ complexes on bipyridinyl functionalized electrodes and nanotube supports.

    PubMed

    Haddad, Raoudha; Gorgy, Karine; Holzinger, Michael; Cosnier, Serge

    2012-06-21

    A simple method is presented to synthesize asymmetric mixed ligand iron(II) diimine complexes using bipyridinyl functionalized carbon nanotubes. The synthesis of these complexes was realized using subsequent dip coating processes. The in situ formed mixed ligand complexes were used in aqueous media to act as building blocks in biosensor devices. PMID:22582181

  1. TSPO Ligand-Methotrexate Prodrug Conjugates: Design, Synthesis, and Biological Evaluation.

    PubMed

    Laquintana, Valentino; Denora, Nunzio; Cutrignelli, Annalisa; Perrone, Mara; Iacobazzi, Rosa Maria; Annese, Cosimo; Lopalco, Antonio; Lopedota, Angela Assunta; Franco, Massimo

    2016-01-01

    The 18-kDa translocator protein (TSPO) is a potential mitochondrial target for drug delivery to tumors overexpressing TSPO, including brain cancers, and selective TSPO ligands have been successfully used to selectively deliver drugs into the target. Methotrexate (MTX) is an anticancer drug of choice for the treatment of several cancers, but its permeability through the blood brain barrier (BBB) is poor, making it unsuitable for the treatment of brain tumors. Therefore, in this study, MTX was selected to achieve two TSPO ligand-MTX conjugates (TSPO ligand α-MTX and TSPO ligand γ-MTX), potentially useful for the treatment of TSPO-rich cancers, including brain tumors. In this work, we have presented the synthesis, the physicochemical characterizations, as well as the in vitro stabilities of the new TSPO ligand-MTX conjugates. The binding affinity for TSPO and the selectivity versus central-type benzodiazepine receptor (CBR) was also investigated. The cytotoxicity of prepared conjugates was evaluated on MTX-sensitive human and rat glioma cell lines overexpressing TSPO. The estimated coefficients of lipophilicity and the stability studies of the conjugates confirm that the synthesized molecules are stable enough in buffer solution at pH 7.4, as well in physiological medium, and show an increased lipophilicity compared to the MTX, compatible with a likely ability to cross the blood brain barrier. The latter feature of two TSPO ligand-MTX conjugates was also confirmed by in vitro permeability studies conducted on Madin-Darby canine kidney cells transfected with the human MDR1 gene (MDCK-MDR1) monolayers. TSPO ligand-MTX conjugates have shown to possess a high binding affinity for TSPO, with IC50 values ranging from 7.2 to 40.3 nM, and exhibited marked toxicity against glioma cells overexpressing TSPO, in comparison with the parent drug MTX. PMID:27322261

  2. TSPO Ligand-Methotrexate Prodrug Conjugates: Design, Synthesis, and Biological Evaluation

    PubMed Central

    Laquintana, Valentino; Denora, Nunzio; Cutrignelli, Annalisa; Perrone, Mara; Iacobazzi, Rosa Maria; Annese, Cosimo; Lopalco, Antonio; Lopedota, Angela Assunta; Franco, Massimo

    2016-01-01

    The 18-kDa translocator protein (TSPO) is a potential mitochondrial target for drug delivery to tumors overexpressing TSPO, including brain cancers, and selective TSPO ligands have been successfully used to selectively deliver drugs into the target. Methotrexate (MTX) is an anticancer drug of choice for the treatment of several cancers, but its permeability through the blood brain barrier (BBB) is poor, making it unsuitable for the treatment of brain tumors. Therefore, in this study, MTX was selected to achieve two TSPO ligand-MTX conjugates (TSPO ligand α-MTX and TSPO ligand γ-MTX), potentially useful for the treatment of TSPO-rich cancers, including brain tumors. In this work, we have presented the synthesis, the physicochemical characterizations, as well as the in vitro stabilities of the new TSPO ligand-MTX conjugates. The binding affinity for TSPO and the selectivity versus central-type benzodiazepine receptor (CBR) was also investigated. The cytotoxicity of prepared conjugates was evaluated on MTX-sensitive human and rat glioma cell lines overexpressing TSPO. The estimated coefficients of lipophilicity and the stability studies of the conjugates confirm that the synthesized molecules are stable enough in buffer solution at pH 7.4, as well in physiological medium, and show an increased lipophilicity compared to the MTX, compatible with a likely ability to cross the blood brain barrier. The latter feature of two TSPO ligand-MTX conjugates was also confirmed by in vitro permeability studies conducted on Madin-Darby canine kidney cells transfected with the human MDR1 gene (MDCK-MDR1) monolayers. TSPO ligand-MTX conjugates have shown to possess a high binding affinity for TSPO, with IC50 values ranging from 7.2 to 40.3 nM, and exhibited marked toxicity against glioma cells overexpressing TSPO, in comparison with the parent drug MTX. PMID:27322261

  3. Bivalent transition metal complexes of ONO donor hydrazone ligand: Synthesis, structural characterization and antimicrobial activity.

    PubMed

    Bhaskar, Ravindra; Salunkhe, Nilesh; Yaul, Amit; Aswar, Anand

    2015-12-01

    Mononuclear transition metal complexes of Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) with a new hydrazone ligand derived from pyrazine-2-carbohydrazide and 2-hydroxyacetophenone have been synthesized. The isolated complexes were characterized by elemental analysis, spectral and analytical methods including elemental analyses, IR, diffuse reflectance, (1)H-NMR, mass spectra, molar conductance, magnetic moment, ESR, XRD, TG and SEM analysis. From the elemental analyses data, the stoichiometry of the complexes was found to be 1:1 (metal:ligand) having the general formulae [M(HL)(Cl)(H2O)2], [M=Mn(II), Co(II), Ni(II) and Cu(II)] and [M(L)(H2O)], [M=Zn(II) and Cd(II)]. The molar conductance values indicate the nonelectrolytic nature of metal complexes. The IR spectral data suggest that the ligand behaves as tridentate moiety with ONO donor atoms sequence towards central metal ion. The Mn(II), Co(II), Ni(II) and Cu(II) complexes have been assigned a monomeric octahedral geometry whereas tetrahedral to Zn(II) and Cd(II) complexes. The antibacterial and antifungal activities of the ligand and its metal complexes were studied against bacterial species Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis, Enterococcus faecalis and Streptococcus pyogenes and fungi Candida albicans, Aspergillus niger and Aspergillus clavatus. The activity data show that the metal complexes have a promising biological activity comparable with the parent ligand against all bacterial and fungal species. PMID:26163785

  4. Investigations of bridging ligands for the synthesis of bimetallic coordination polymers

    NASA Astrophysics Data System (ADS)

    Glynn, Christopher W.

    The synthesis and study of new transition metal coordination complexes that display spontaneous magnetic moments is the goal of the present research. Materials of this kind represent a new class of magnetic compounds, molecular-based magnets. For our purposes, transition metal ions provide the source of the magnetic moments, which are bridged by organic ligands. The systems we have designed are bimetallic coordination polymers with two alternating transition metal ions, M1 and M2, with inequivalent non-zero moments. The primary difficulty encountered in the design strategy is how to arrange two chemically similar transition metal ions in an alternating pattern. The organic ligands 2,6-bis-(1'-triazolo)-pyridine (btpy), 2,6-bis(4'-imidazolo)pyridine (H2bimpy), 2,2'-biimidazole (2,2'-H2biim), 4,4'-biimidazole (4,4'-H2biim), and 2,6-diacetylpyridine dioxime (H2dapd) were investigated for use in constructing site-ordered bimetallic coordination polymers. All five ligands share the following characteristics: a polydentate internal binding site, the possibility of external binding sites in a square-planar or octahedral arrangement and the potential to mediate magnetic exchange between the transition metals ions coordinated to the distinct internal and external binding sites. The systems based on H2bimpy and 4,4'-H 2biim are promising, but difficulties in the preparation of the ligands have prevented the realization of these systems. Transition metal complexes for the ligands btpy, 2,2'-H2biim and H 2dapd have been prepared and characterized. Although to date no bimetallic materials have been constructed through the use of these ligands, the data presented indicates their viability for the construction of bimetallic coordination polymers.

  5. Direct synthesis of thiolate-protected gold nanoparticles using Bunte salts as ligand precursors: investigations of ligand shell formation and core growth

    NASA Astrophysics Data System (ADS)

    Lohse, Samuel E.

    2011-12-01

    Applications of ligand-protected nanoparticles have increased markedly in recent years, yet their controlled synthesis remains an under-developed field. Nanoparticle syntheses are highly specialized in their execution and often possess significant limitations. For example, the synthesis of thiol-stabilized gold nanoparticles (AuNPs) with core diameters greater than 5.0 nm is difficult to achieve using existing methods. This dissertation describes the development of a synthetic strategy for thiolate-stabilized AuNPs over a wide range of core sizes using alkyl thiosulfates (Bunte salts) as ligand precursors. The use of Bunte salts permits the synthesis of larger AuNPs than can be achieved using thiols by allowing the AuNP cores to grow to larger diameters before the formation of the thiolate ligand shell. Chapter II details the development of a direct synthesis strategy using Bunte salts as ligand precursors that produces AuNPs with diameters up to 20 nm. Chapter III describes an investigation of the ligand shell formation that occurs during these syntheses. The ligand shell formation involves the adsorption of the Bunte salt to the AuNP surface, where it is converted to the thiolate. This conversion requires an excess of sodium borohydride in the synthesis of >5 nm AuNPs, but not for the synthesis of smaller AuNPs. This synthetic strategy was adapted for use in flow reactors to attain simultaneous AuNP synthesis and characterization. Chapter IV demonstrates that thiol-stabilized AuNPs can be synthesized in a microfluidic device with product monitoring provided by UV-vis absorbance spectroscopy. The development of a capillary flow reactor that permits the incorporation of new monitoring techniques is presented in Chapter V. The incorporation of Small-Angle X-ray Scattering (SAXS) analysis provides quantitative in situ determinations of AuNP diameter. The combination of synthetic control and monitoring makes capillary flow reactors powerful tools for optimization of

  6. Synthesis, Characterization and Biological Evaluation of Transition Metal Complexes Derived from N, S Bidentate Ligands

    PubMed Central

    Md Yusof, Enis Nadia; Ravoof, Thahira Begum S. A.; Tiekink, Edward R. T.; Veerakumarasivam, Abhimanyu; Crouse, Karen Anne; Mohamed Tahir, Mohamed Ibrahim; Ahmad, Haslina

    2015-01-01

    Two bidentate NS ligands were synthesized by the condensation reaction of S-2-methylbenzyldithiocarbazate (S2MBDTC) with 2-methoxybenzaldehyde (2MB) and 3-methoxybenzaldehyde (3MB). The ligands were reacted separately with acetates of Cu(II), Ni(II) and Zn(II) yielding 1:2 (metal:ligand) complexes. The metal complexes formed were expected to have a general formula of [M(NS)2] where M = Cu2+, Ni2+, and Zn2+. These compounds were characterized by elemental analysis, molar conductivity, magnetic susceptibility and various spectroscopic techniques. The magnetic susceptibility measurements and spectral results supported the predicted coordination geometry in which the Schiff bases behaved as bidentate NS donor ligands coordinating via the azomethine nitrogen and thiolate sulfur. The molecular structures of the isomeric S2M2MBH (1) and S2M3MBH (2) were established by X-ray crystallography to have very similar l-shaped structures. The Schiff bases and their metal complexes were evaluated for their biological activities against estrogen receptor-positive (MCF-7) and estrogen receptor-negative (MDA-MB-231) breast cancer cell lines. Only the Cu(II) complexes showed marked cytotoxicity against the cancer cell lines. Both Schiff bases and other metal complexes were found to be inactive. In concordance with the cytotoxicity studies, the DNA binding studies indicated that Cu(II) complexes have a strong DNA binding affinity. PMID:25988384

  7. Flexible Cyclic Ethers/Polyethers as Novel P2-Ligands for HIV-1 Protease Inhibitors: Design, Synthesis, Biological Evaluation, and Protein-Ligand X-Ray Studies

    SciTech Connect

    Ghosh, Arun; Gemma, Sandra; Baldridge, Abigal; Wang, Yuan-Fang; Kovalevsky, Andrey; Koh, Yashiro; Weber, Irene; Mitsuya, Hiroaki

    2008-12-05

    We report the design, synthesis, and biological evaluation of a series of novel HIV-1 protease inhibitors. The inhibitors incorporate stereochemically defined flexible cyclic ethers/polyethers as high affinity P2-ligands. Inhibitors containing small ring 1,3-dioxacycloalkanes have shown potent enzyme inhibitory and antiviral activity. Inhibitors 3d and 3h are the most active inhibitors. Inhibitor 3d maintains excellent potency against a variety of multi-PI-resistant clinical strains. Our structure-activity studies indicate that the ring size, stereochemistry, and position of oxygens are important for the observed activity. Optically active synthesis of 1,3-dioxepan-5-ol along with the syntheses of various cyclic ether and polyether ligands have been described. A protein-ligand X-ray crystal structure of 3d-bound HIV-1 protease was determined. The structure revealed that the P2-ligand makes extensive interactions including hydrogen bonding with the protease backbone in the S2-site. In addition, the P2-ligand in 3d forms a unique water-mediated interaction with the NH of Gly-48.

  8. Synthesis and Reactivity of a Bio-inspired Dithiolene Ligand and its Mo Oxo Complex.

    PubMed

    Porcher, Jean-Philippe; Fogeron, Thibault; Gomez-Mingot, Maria; Chamoreau, Lise-Marie; Li, Yun; Fontecave, Marc

    2016-03-18

    An original synthesis of the fused pyranoquinoxaline dithiolene ligand qpdt(2-) is discussed in detail. The most intriguing step is the introduction of the dithiolene moiety by Pd-catalyzed carbon-sulfur coupling. The corresponding Mo(IV) O complex (Bu4 N)2 [MoO(qpdt)2 ] (2) underwent reversible protonation in a strongly acidic medium and remained stable under anaerobic conditions. Besides, 2 was found to be very sensitive towards oxygen, as upon oxidation it formed a planar dithiin derivative. Moreover, the qpdt(2-) ligand in the presence of [MoCl4 (tBuNC)2 ] formed a tetracyclic structure. The products resulting from the unique reactivity of qpdt(2-) were characterized by X-ray diffraction, mass spectrometry, NMR spectroscopy, UV/Vis spectroscopy, and electrochemistry. Plausible mechanisms for the formation of these products are also proposed. PMID:26880579

  9. Synthesis and Reactivity of Palladium(II) Fluoride Complexes Containing Nitrogen-Donor Ligands

    PubMed Central

    Ball, Nicholas D.; Kampf, Jeff W.; Sanford, Melanie S.

    2010-01-01

    This article describes the synthesis, characterization, and reactivity of palladium(II) fluoride complexes containing sp2 and sp3 nitrogen-containing supporting ligands. Both cis and trans complexes of general structure (N)(N’)PdII(R)(F) (R = Ar or CH3) as well as cis-(N)2PdII(F)2 are reported. Crystallographic characterization of these molecules has allowed structural comparisons to related phosphine-ligated species. Furthermore, these studies have revealed that nitrogen-donor ligands support some of the longest and the shortest Pd–F bonds reported to date. The thermal decomposition of (N)(N’)PdII(R)(F) has also been examined, and no products of C–F bond-forming reductive elimination were obtained in any cases. PMID:20024002

  10. Trivalent nickel. The quinone oximate family: synthesis and redox regulation of isomerism and ligand redistribution

    SciTech Connect

    Ray, D.; Chakravorty, A.

    1988-09-21

    The synthesis of the tris chelates Ni/sup III/(RQ)/sub 3/ by electrooxidation of Ni/sup II/(RQ)/sub 3/- (HRQ = quinone monoximes) is reported. These complexes have afforded a unique opportunity for voltammetric and spectroscopic examination of geometric isomerism and isomer preferences of the two oxidation states of nickel in a N/sub 2/O/sub 3/ environment. A redox-driven ligand redistribution reaction that furnishes Ni(RQ)/sub 3/ following electrooxidation of Ni/sup II/(RQ)/sub 3/(N,N) to Ni/sup III/(RQ)/sub 2/(N,N)/sup +/, where N,N represents amine coordination is reported. The effects of geometric structure, substituents, and ligands on the Ni(III)-Ni(II) reduction potential in Ni(RQ)/sub 3/ and Ni(RQ)/sub 2/(N,N)/sup +/ are noted. 29 references, 5 figures, 4 tables.

  11. A new dioxime ligand and its trinuclear copper(II) complex: Synthesis, characterization and optical properties

    NASA Astrophysics Data System (ADS)

    Karipcin, Fatma; Dede, Bülent; Caglar, Yasemin; Hür, Deniz; Ilican, Saliha; Caglar, Mujdat; Şahin, Yücel

    2007-04-01

    The synthesis and characterization of a new dioxime ligand, (H2L), (III) and its trinuclear copper(II) complex, [Cu3L2(H2O)2](ClO4)2, (V) is described. IR spectra show that the ligand acts in a tetradentate manner and coordinates N4 donor groups of H2L to copper(II) ion. The structure of the metal chelate is clarified with the help of elemental analysis, magnetic moment, conductometric and spectroscopic measurements. The optical absorption studies reveal that the transition is direct with band gap energy values are calculated. The optical constants such as refractive index and dielectric constant of the compound were determined. The refractive index dispersion curves of the films obey the single-oscillator model and oscillator parameters. Optical dispersion parameters E0 and Ed developed by Wemple-DiDomenico were calculated.

  12. Pharmacologically significant complexes of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) of novel Schiff base ligand, (E)-N-(furan-2-yl methylene) quinolin-8-amine: Synthesis, spectral, XRD, SEM, antimicrobial, antioxidant and in vitro cytotoxic studies

    NASA Astrophysics Data System (ADS)

    Shakir, M.; Hanif, Summaiya; Sherwani, Mohd. Asif; Mohammad, Owais; Al-Resayes, Saud I.

    2015-07-01

    A novel series of metal complexes of the types, [ML2(H2O)2]Cl2 and [ML2]Cl2 [M = Mn(II), 1; Co(II), 2; Ni(II), 3; Cu(II), 4; and Zn(II), 5] were synthesized by the interaction of ligand, L (E)-N-(furan-2-yl methylene) quinolin-8-amine, derived from the condensation of 2-furaldehyde and 8-aminoquinoline. The synthesized ligand and its metal complexes were characterized on the basis of results obtained from elemental analysis, ESI-MS, XRD, SEM, TGA/DTA, FT-IR, UV-Vis, magnetic moment and 1H and 13C NMR spectroscopic studies. EPR parameters were recorded in case of complex 4. The comparative in-vitro antimicrobial activities against various pathogens with reference to known antibiotics and antioxidant activity against standard control at variable concentrations revealed that the metal complexes show enhanced antimicrobial and free radical scavenging activities in general as compared to free ligand. However, the complexes 1 and 5 have shown best antioxidant activity among all the metal complexes. Furthermore, comparative in-vitro antiproliferative activity on ligand and its metal chelates performed on MDA-MB-231 (breast carcinoma), KCL22 (blood lymphoid carcinoma), HeLa (cervical carcinoma) cell lines and normal cells (PBMC) revealed that metal chelates show moderate to good activity as compared to ligand where as complex 1 seems to be the most promising one possessing a broad spectrum of activity against all the selected cancer cell lines with IC50 < 2.10 μM.

  13. Nano structure zinc (II) Schiff base complexes of a N3-tridentate ligand as new biological active agents: Spectral, thermal behaviors and crystal structure of zinc azide complex

    NASA Astrophysics Data System (ADS)

    Montazerozohori, M.; Mojahedi Jahromi, S.; Masoudiasl, A.; McArdle, P.

    2015-03-01

    In this work, synthesis of some new five coordinated zinc halide/pseudo-halide complexes of a N3-tridentate ligand is presented. All complexes were subjected to spectroscopic and physical methods such as FT-IR, UV-visible, 1H and 13C NMR spectra, thermal analyses and conductivity measurements for identification. Based on spectral data, the general formula of ZnLX2 (X = Cl-, Br-, I-, SCN- and N3-) was proposed for the zinc complexes. Zinc complexes have been also prepared in nano-structure sizes under ultrasonic irradiation. X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were applied for confirmation of nano-structure character for the complexes. Among the complexes, zinc azide complex structure was analyzed by X-ray crystallography. This complex crystallizes as a triplet in trigonal system with space group of P31. The coordination sphere around the zinc center is well shown as a distorted trigonal bipyramidal with three nitrogen atoms from Schiff base ligand and two terminal azide nitrogen atoms attached to zinc ion. Various intermolecular interactions such as Nsbnd H⋯N, Csbnd H⋯N and Csbnd H⋯π hydrogen bonding interactions stabilize crystalline lattice so that they causes a three dimensional supramolecular structure for the complex. In vitro screening of the compounds for their antimicrobial activities showed that ZnLI2, ZnL(N3)2, ZnLCl2 and ZnL(NCS)2 were found as the most effective compound against bacteria of Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli respectively. Also ZnLI2 and ZnLCl2 complexes were found more effective against two selected fungi than others. Finally, thermal behaviors of the zinc complexes showed that they are decomposed via 2-4 thermal steps from room temperature up to 1000 °C.

  14. Synthesis of New Bis(3-hydroxy-4-pyridinone) Ligands as Chelating Agents for Uranyl Complexation.

    PubMed

    Jin, Bo; Zheng, Rongzong; Peng, Rufang; Chu, Shijin

    2016-01-01

    Five new bis(3-hydroxy-4-pyridinone) tetradentate chelators were synthesized in this study. The structures of these tetradentate chelators were characterized by ¹H-NMR, (13)C-NMR, FT-IR, UV-vis, and mass spectral analyses. The binding abilities of these tetradentate chelators for uranyl ion at pH 7.4 were also determined by UV spectrophotometry in aqueous media. Results showed that the efficiencies of these chelating agents are dependent on the linker length. Ligand 4b is the best chelator and suitable for further studies. PMID:27005598

  15. Synthesis and Characterization of a Tetrapodal NO4(4-) Ligand and Its Transition Metal Complexes.

    PubMed

    Axelson, Jordan C; Gonzalez, Miguel I; Meihaus, Katie R; Chang, Christopher J; Long, Jeffrey R

    2016-08-01

    We present the synthesis and characterization of alkali metal salts of the new tetraanionic, tetrapodal ligand 2,2'-(pyridine-2,6-diyl)bis(2-methylmalonate) (A4[PY(CO2)4], A = Li(+), Na(+), K(+), and Cs(+)), via deprotection of the neutral tetrapodal ligand tetraethyl 2,2'-(pyridine-2,6-diyl)bis(2-methylmalonate) (PY(CO2Et)4). The [PY(CO2)4](4-) ligand is composed of an axial pyridine and four equatorial carboxylate groups and must be kept at or below 0 °C to prevent decomposition. Exposing it to a number of divalent first-row transition metals cleanly forms complexes to give the series K2[(PY(CO2)4)M(H2O)] (M = Mn(2+), Fe(2+), Co(2+), Ni(2+), Zn(2+)). The metal complexes were comprehensively characterized via single-crystal X-ray diffraction, (1)H NMR and UV-vis absorption spectroscopy, and cyclic voltammetry. Crystal structures reveal that [PY(CO2)4](4-) coordinates in a pentadentate fashion to allow for a nearly ideal octahedral coordination geometry upon binding an exogenous water ligand. Additionally, depending on the nature of the charge-balancing countercation (Li(+), Na(+), or K(+)), the [(PY(CO2)4)M(H2O)](2-) complexes can assemble in the solid state to form one-dimensional channels filled with water molecules. Aqueous electrochemistry performed on [(PY(CO2)4)M(H2O)](2-) suggested accessible trivalent oxidation states for the Fe, Co, and Ni complexes, and the trivalent Co(3+) species [(PY(CO2)4)Co(OH)](2-) could be isolated via chemical oxidation. The successful synthesis of the [PY(CO2)4](4-) ligand and its transition metal complexes illustrates the still-untapped versatility within the tetrapodal ligand family, which may yet hold promise for the isolation of more reactive and higher-valent metal complexes. PMID:27404805

  16. Synthesis and coordination chemistry of tridentate (PNN) amine enamido phosphine ligands with ruthenium.

    PubMed

    Wambach, T C; Lenczyk, C; Patrick, B O; Fryzuk, M D

    2016-04-01

    Tridentate amine-imine-phosphine ligands, R2PC5H7NC2H4NEt2 [(R)PNN(H)], where R = Pr(i) or Bu(t) are synthesized using a straightforward protocol of condensation, deprotonation, and addition of a chlorodialkylphosphine. Multinuclear NMR spectroscopy shows the ligands exist exclusively in the enamine tautomeric form in solution. Treating these ligands with RuHCl(PPr(i)3)2(CO) forms the desired coordination compounds, RuHCl[(R)PNN(H)](CO), where the imine tautomeric form of the ligands coordinates to ruthenium. Deuterium labelling experiments show Ru-H/N-D scrambling occurs during ligand coordination. Treating the RuHCl[(R)PNN(H)](CO) precursors with potassium tert-butoxide allows for the synthesis of two new ruthenium enamido-phosphine complexes, RuH[(R)PNN](CO), which were fully characterized. The structure of one of the derivatives was confirmed by X-ray crystallography (R = Pr(i)). The reactivity of the enamido-phosphine complexes with H2 and benzyl alcohol is also reported. For the enamido phosphine complex where R = Pr(i), the reaction with H2 is reversible and forms (RuH(CO)[(Pri)PNN(H)])2(μ-H)2, a hydride-bridged dimer that results from cooperative activation of H2. The reactivity of both amine-enamido-phosphine ruthenium compounds with benzyl alcohol establishes that the complexes are catalyst precursors for acceptorless dehydrogenation (AD), although the turnover frequencies measured using both catalyst precursors are modest. PMID:26916542

  17. Synthesis, spectral characterization, structural investigation and antimicrobial studies of mononuclear Cu(II), Ni(II), Co(II), Zn(II) and Cd(II) complexes of a new potentially hexadentate N2O4 Schiff base ligand derived from salicylaldehyde

    NASA Astrophysics Data System (ADS)

    Keypour, Hassan; Shayesteh, Maryam; Rezaeivala, Majid; Chalabian, Firoozeh; Elerman, Yalcin; Buyukgungor, Orhan

    2013-01-01

    A new potentially hexadentate N2O4 Schiff base ligand, H2L derived from condensation reaction of an aromatic diamine and salicylaldehyde, and its metal complexes were characterized by elemental analyses, IR, UV-Vis, EI-MS, 1H and 13C NMR spectra, as well as conductance measurements. It has been originated that the Schiff base ligand with Cu(II), Ni(II), Co(II), Cd(II) and Zn(II) ions form mononuclear complexes on 1:1 (metal:ligand) stoichiometry. The conductivity data confirm the non-electrolytic nature of the complexes. Also the crystal structures of the complexes [ZnL] and [CoL] have also been determined by using X-ray crystallographic technique. The Zn(II) and Co(II) complexes show a tetrahedral configuration. Electronic absorption spectra of the Cu(II) and Ni(II) complexes suggest a square-planar geometry around the central metal ion. The synthesized compounds have antibacterial activity against the three Gram-positive bacteria: Bacillus cereus, Enterococcus faecalis and Listeria monocytogenes and also against the three Gram-negative bacteria: Salmonella paraB, Citrobacter freundii and Enterobacter aerogenes. The results showed that in some cases the antibacterial activity of complexes were more than nalidixic acid and amoxicillin as standards.

  18. Hydrothermal reactions: From the synthesis of ligand to new lanthanide 3D-coordination polymers

    SciTech Connect

    Silva, Fausthon Fred da; Fernandes de Oliveira, Carlos Alberto; Lago Falcão, Eduardo Henrique; Gatto, Claudia Cristina; Bezerra da Costa, Nivan; Oliveira Freire, Ricardo; Chojnacki, Jarosław; Alves Júnior, Severino

    2013-11-15

    The organic ligand 2,5-piperazinedione-1,4-diacetic acid (H{sub 2}PDA) was synthesized under hydrothermal conditions starting from the iminodiacetic acid and catalyzed by oxalic acid. The X-ray powder diffraction data indicates that the compound crystallizes in the P2{sub 1}/c monoclinic system as reported in the literature. The ligand was also characterized by elemental analysis, magnetic nuclear resonance, infrared spectroscopy and thermogravimetric analysis. Two new coordination networks based on lanthanide ions were obtained with this ligand using hydrothermal reaction. In addition to single-crystal X-ray diffraction, the compounds were characterized by infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy and elemental analysis. Single-crystal XRD showed that the compounds are isostructural, crystallizing in P2{sub 1}/n monoclinic system with chemical formula [Ln(PDA){sub 1.5}(H{sub 2}O)](H{sub 2}O){sub 3} (Ln=Gd{sup 3+}(1) and Eu{sup 3+}(2)).The luminescence properties of both compounds were studied. In the compound (1), a broad emission band was observed at 479 nm, redshifted by 70 nm in comparison of the free ligand. In (2), the typical f–f transition was observed with a maximum peak at 618 nm, related with the red emission of the europium ions. Computational methods were performed to simulate the crystal structure of (2). The theoretical calculations of the intensity parameters are in good agreement with the experimental values. - Graphical abstract: Scheme of obtaining the ligand 2,5-piperazinedione-1,4-diacetic acid (H{sub 2}PDA) and two new isostructural 3D-coordination polymers [Ln(PDA){sub 1.5}(H{sub 2}O)](H{sub 2}O){sub 3} (Ln=Gd{sup 3+} and Eu{sup 3+}) by hydrothermal synthesis. Display Omitted - Highlights: • The ligand 2,5-piperazinedione-1,4-diacetic acid was synthetized using the hydrothermic method and characterized. • Two new 3D-coordination polymers with this ligand containing Gd{sup 3+} and Eu{sup 3+} ions

  19. Highly Potent HIV-1 Protease Inhibitors with Novel Tricyclic P2 Ligands: Design, Synthesis, and Protein-Ligand X-ray Studies

    SciTech Connect

    Ghosh, Arun K.; Parham, Garth L.; Martyr, Cuthbert D.; Nyalapatla, Prasanth R.; Osswald, Heather L.; Agniswamy, Johnson; Wang, Yuan-Fang; Amano, Masayuki; Weber, Irene T.; Mitsuya, Hiroaki

    2013-10-08

    The design, synthesis, and biological evaluation of a series of HIV-1 protease inhibitors incorporating stereochemically defined fused tricyclic P2 ligands are described. Various substituent effects were investigated to maximize the ligand-binding site interactions in the protease active site. Inhibitors 16a and 16f showed excellent enzyme inhibitory and antiviral activity, although the incorporation of sulfone functionality resulted in a decrease in potency. Both inhibitors 16a and 16f maintained activity against a panel of multidrug resistant HIV-1 variants. A high-resolution X-ray crystal structure of 16a-bound HIV-1 protease revealed important molecular insights into the ligand-binding site interactions, which may account for the inhibitor’s potent antiviral activity and excellent resistance profiles.

  20. X-ray absorption spectral studies of copper (II) mixed ligand complexes

    NASA Astrophysics Data System (ADS)

    Soni, B.; Dar, Davood Ah; Shrivastava, B. D.; Prasad, J.; Srivastava, K.

    2014-09-01

    X-ray absorption spectra at the K-edge of copper have been studied in two copper mixed ligand complexes, one having tetramethyethylenediamine (tmen) and the other having tetraethyethylenediamine (teen) as one of the ligands. The spectra have been recorded at BL-8 dispersive extended X-ray absorption fine structure (EXAFS) beamline at the 2.5 GeV INDUS- 2 synchrotron, RRCAT, Indore, India. The data obtained has been processed using the data analysis program Athena. The energy of the K-absorption edge, chemical shift, edge-width and shift of the principal absorption maximum in the complexes have been determined and discussed. The values of these parameters have been found to be approximately the same in both the complexes indicating that the two complexes possess similar chemical environment around the copper metal atom. The chemical shift has been utilized to estimate effective nuclear charge on the absorbing atom. The normalized EXAFS spectra have been Fourier transformed. The position of the first peak in the Fourier transform gives the value of first shell bond length, which is shorter than the actual bond length because of energy dependence of the phase factors in the sine function of the EXAFS equation. This distance is thus the phase- uncorrected bond length. Bond length has also been determined by Levy's, Lytle's and Lytle, Sayers and Stern's (LSS) methods. The results obtained from LSS and the Fourier transformation methods are comparable with each other, since both are phase uncorrected bond lengths.

  1. Synthesis of chiral biphenol-based diphosphonite ligands and their application in palladium-catalyzed intermolecular asymmetric allylic amination reactions.

    PubMed

    Shi, Ce; Chien, Chih-Wei; Ojima, Iwao

    2011-02-01

    A library of new 2,2'-bis(diphenylphosphinoyloxy)-1,1'-binaphthyl (binapo)-type chiral diphosphonite ligands was designed and synthesized based on chiral 3,3',5,5',6,6'-hexasubstituted biphenols. These bop ligands have exhibited excellent efficiency in a palladium-catalyzed intermolecular allylic amination reaction, which provides a key intermediate for the total synthesis of Strychnos indole alkaloids with enantiopurities of up to 96% ee. PMID:21254441

  2. Multicomponent Synthesis and Biological Evaluation of a Piperazine-Based Dopamine Receptor Ligand Library.

    PubMed

    Stucchi, Mattia; Gmeiner, Peter; Huebner, Harald; Rainoldi, Giulia; Sacchetti, Alessandro; Silvani, Alessandra; Lesma, Giordano

    2015-08-13

    A series of 1,4-disubstituted piperazine-based compounds were designed, synthesized, and evaluated as dopamine D2/D3 receptor ligands. The synthesis relies on the key multicomponent split-Ugi reaction, assessing its great potential in generating chemical diversity around the piperazine core. With the aim of evaluating the effect of such diversity on the dopamine receptor affinity, a small library of compounds was prepared, applying post-Ugi transformations. Ligand stimulated binding assays indicated that some compounds show a significant affinity, with K i values up to 53 nM for the D2 receptor. Molecular docking studies with the D2 and D3 receptor homology models were also performed on selected compounds. They highlighted key interactions at the indole head and at the piperazine moiety, which resulted in good agreement with the known pharmacophore models, thus helping to explain the observed structure-activity relationship data. Molecular insights from this study could enable a rational improvement of the split-Ugi primary scaffold, toward more selective ligands. PMID:26288260

  3. Synthesis of ligand-free CZTS nanoparticles via a facile hot injection route.

    PubMed

    Mirbagheri, N; Engberg, S; Crovetto, A; Simonsen, S B; Hansen, O; Lam, Y M; Schou, J

    2016-05-01

    Single-phase, ligand-free Cu2ZnSnS4 (CZTS) nanoparticles that can be dispersed in polar solvents are desirable for thin film solar cell fabrication, since water can be used as the solvent for the nanoparticle ink. In this work, ligand-free nanoparticles were synthesized using a simple hot injection method and the precursor concentration in the reaction medium was tuned to control the final product. The as-synthesized nanoparticles were characterized using various techniques, and were found to have a near-stoichiometric composition and a phase-pure kesterite crystal structure. No secondary phases were detected with Raman spectroscopy or scanning transmission electron microscopy energy dispersive x-ray spectroscopy. Furthermore, high resolution transmission electron microscopy showed large-sized nanoparticles with an average diameter of 23 nm ± 11 nm. This approach avoids all organic materials and toxic solvents that otherwise could hinder grain growth and limit the deposition techniques. In addition the synthesis route presented here results in nanoparticles of a large size compared to other ligand-free CZTS nanoparticles, due to the high boiling point of the solvents selected. Large particle size in CZTS nanoparticle solar cells may lead to a promising device performance. The results obtained demonstrate the suitability of the synthesized nanoparticles for application in low cost thin film solar cells. PMID:27005863

  4. Synthesis of ligand-free CZTS nanoparticles via a facile hot injection route

    NASA Astrophysics Data System (ADS)

    Mirbagheri, N.; Engberg, S.; Crovetto, A.; Simonsen, S. B.; Hansen, O.; Lam, Y. M.; Schou, J.

    2016-05-01

    Single-phase, ligand-free Cu2ZnSnS4 (CZTS) nanoparticles that can be dispersed in polar solvents are desirable for thin film solar cell fabrication, since water can be used as the solvent for the nanoparticle ink. In this work, ligand-free nanoparticles were synthesized using a simple hot injection method and the precursor concentration in the reaction medium was tuned to control the final product. The as-synthesized nanoparticles were characterized using various techniques, and were found to have a near-stoichiometric composition and a phase-pure kesterite crystal structure. No secondary phases were detected with Raman spectroscopy or scanning transmission electron microscopy energy dispersive x-ray spectroscopy. Furthermore, high resolution transmission electron microscopy showed large-sized nanoparticles with an average diameter of 23 nm ± 11 nm. This approach avoids all organic materials and toxic solvents that otherwise could hinder grain growth and limit the deposition techniques. In addition the synthesis route presented here results in nanoparticles of a large size compared to other ligand-free CZTS nanoparticles, due to the high boiling point of the solvents selected. Large particle size in CZTS nanoparticle solar cells may lead to a promising device performance. The results obtained demonstrate the suitability of the synthesized nanoparticles for application in low cost thin film solar cells.

  5. Ruthenium(ii) complexes of hemilabile pincer ligands: synthesis and catalysing the transfer hydrogenation of ketones.

    PubMed

    Nair, Ashwin G; McBurney, Roy T; Walker, D Barney; Page, Michael J; Gatus, Mark R D; Bhadbhade, Mohan; Messerle, Barbara A

    2016-09-28

    A series of Ru(ii) complexes were synthesised based on a hemilabile pyrazole-N-heterocyclic carbene (NHC)-pyrazole (C3N2H3)CH2(C3N2H2)CH2(C3N2H3) NCN pincer ligand 1. All complexes were fully characterised using single crystal X-ray crystallography and multinuclear NMR spectroscopy. Hemilabile ligands provide flexible coordination modes for the coordinating metal ion which can play a significant effect on the efficiency and mechanism of catalysis by the resulting complex. Here we observed and isolated mono-, bi- and tri-dentate complexes of both Ag(i) and Ru(ii) with 1 in which the resultant coordination mode was controlled by careful reagent selection. The catalytic activity of the Ru(ii) complexes for the transfer hydrogenation reaction of acetophenone with isopropanol was investigated. The unexpected formation of the pentaborate anion, [B5O6(OH)4](-), during the synthesis of complex 6a was found to have an unexpected positive effect by enhancing the catalysis rate. This work provides insights into the roles that different coordination modes, counterions and ligand hemilability play on the catalytic activity in transfer hydrogenations. PMID:27539740

  6. Multicomponent Synthesis and Biological Evaluation of a Piperazine-Based Dopamine Receptor Ligand Library

    PubMed Central

    2015-01-01

    A series of 1,4-disubstituted piperazine-based compounds were designed, synthesized, and evaluated as dopamine D2/D3 receptor ligands. The synthesis relies on the key multicomponent split-Ugi reaction, assessing its great potential in generating chemical diversity around the piperazine core. With the aim of evaluating the effect of such diversity on the dopamine receptor affinity, a small library of compounds was prepared, applying post-Ugi transformations. Ligand stimulated binding assays indicated that some compounds show a significant affinity, with Ki values up to 53 nM for the D2 receptor. Molecular docking studies with the D2 and D3 receptor homology models were also performed on selected compounds. They highlighted key interactions at the indole head and at the piperazine moiety, which resulted in good agreement with the known pharmacophore models, thus helping to explain the observed structure–activity relationship data. Molecular insights from this study could enable a rational improvement of the split-Ugi primary scaffold, toward more selective ligands. PMID:26288260

  7. Synthesis, crystal structure, spectral characterization and biological exploration of water soluble Cu(II) complexes of vitamin B6 derivative.

    PubMed

    Annaraj, B; Neelakantan, M A

    2015-09-18

    The synthesis and characterization of Copper(II) complexes of a Schiff base derived from vitamin B6 component (pyridoxal) and ethanol amine [CuL2] (1), and its mixed ligand complexes [Cu(L)(N,N')]NO3, where N,N' is bipyridine (2) and 1,10-phenanthroline (3) are reported, including the X-ray crystal structures of [CuL2] (1). The crystal structure of 1 has square planar geometry with ligand to the metal ratio 2:1. The molecules are assembled in 3D supramolecular structure through hydrogen bonding interactions. DNA is considered as the major pharmacological target of metal based drugs, the objective of the present work includes the understanding of DNA binding mode of the synthesized compounds. The complexes bind with DNA through non intercalative interaction has been evidenced from the results of UV-Visible and fluorescence spectral titrations. It is further validated by molecular docking studies. Bovine serum albumin (BSA) binding studies revealed that the complexes can strongly quench the intrinsic fluorescence of BSA through a static quenching mechanism. The complexes promote the DNA cleavage even in the absence of additives which follows the order 2 > 1 > 3. Further, the complexes show potential cytotoxicity towards human breast cancer cell MCF-7 and induce the cell death. PMID:26241872

  8. Ligand-Controlled Synthesis of Azoles via Ir-Catalyzed Reactions of Sulfoxonium Ylides with 2-Amino Heterocycles.

    PubMed

    Phelps, Alicia M; Chan, Vincent S; Napolitano, José G; Krabbe, Scott W; Schomaker, Jennifer M; Shekhar, Shashank

    2016-05-20

    An iridium-catalyzed method was developed for the synthesis of imidazo-fused pyrrolopyrazines. The presence or absence of a nitrogenated ligand controlled the outcome of the reaction, leading to simple β-keto amine products in the absence of added ligand and the cyclized 7- and 8-substituted-imidazo[1,2-a]pyrrolo[2,3-e]pyrazine products in the presence of ligand. This catalyst control was conserved across a variety of ylide and amine coupling partners. The substrate was shown to act as a ligand for the iridium catalyst in the absence of other ligands via NMR spectroscopy. Kinetic studies indicated that formation of the Ir-carbene was reversible and the slow step of the reaction. These mechanistic investigations suggest that the β-keto amine products form via an intramolecular carbene N-H insertion, and the imidazopyrrolopyrazines form via an intermolecular carbene N-H insertion. PMID:27104299

  9. Design, classification, and strategies of synthesis of modular bidentate ligands based on aryl[2.2]paracyclophane backbone.

    PubMed

    Rozenberg, Valeria; Zhuravsky, Roman; Sergeeva, Elena

    2006-02-01

    The aryl[2.2]paracyclophane backbone, which is a "hybrid" of a configurationally rigid [2.2]paracyclophanyl unit and a biphenyl unit, is proposed as a new source for the chiral ligands. Classification of such ligands in accordance with mutual arrangement of the functional substituents and their nature is also introduced. Key strategic approaches to the synthesis of regioisomeric biphenols and hydroxyaldehydes, including Suzuki cross-coupling reaction, lithiation/electrophilic quench, and chiral resolution, are elaborated. Examples of their further modification and application of several O,O- and N,O-ligands as chiral inductors in asymmetric catalysis are described. PMID:16385621

  10. Features of spectral properties of Sm3 + complexes with dithia- and diselenophosphinate ligands

    NASA Astrophysics Data System (ADS)

    Pushkarev, A. P.; Yablonskiy, A. N.; Yunin, P. A.; Burin, M. E.; Andreev, B. A.; Bochkarev, M. N.

    2016-06-01

    The samarium complexes Sm(S2PPh2)3(THF)2 (1) and Sm(Se2PPh2)3(THF)2 (2) with soft-donor dithia- and diselenophosphinate ligands were synthesized and their photophysical properties were studied in detail. Both complexes displayed the metal-centered photoluminescence (PL) in visible and NIR regions corresponding to 4G5/2 → 6HJ (J = 5/2, 7/2, 9/2, 11/2, 13/2, 15/2), 6FJ (J = 1/2, 3/2, 5/2, 7/2, 9/2, 11/2) f-f transitions of Sm3 +. Luminescence decay curves exhibit an initial short build-up region and can be described by double or triple exponential function owing to multiphonon relaxation from the 4F3/2 energy level to the 4G5/2 one and reversible energy transfer from the Sm3 + excited states to the triplet (3T1) state of phosphinate ligand. A Judd-Ofelt analysis was performed to estimate PL quantum efficiency (QE), branching ratios (β) and induced-emission cross section (σem) of the compounds obtained. It was found that the Judd-Ofelt parameter Ω2 of 1 is significantly greater than that of 2. This feature is responsible for large values of β (50.98%) and σem (4.29 × 10- 21 cm2) which suggest 1 as a good candidate for the development of samarium doped polymethylmethacrylate (PMMA) laser medium acting on the 4G5/2 → 6H9/2 transition at 645 nm. The estimated room-temperature PL QE of 1 and 2 equals to 1.9 and 0.17%, respectively.

  11. Features of spectral properties of Sm(3+) complexes with dithia- and diselenophosphinate ligands.

    PubMed

    Pushkarev, A P; Yablonskiy, A N; Yunin, P A; Burin, M E; Andreev, B A; Bochkarev, M N

    2016-06-15

    The samarium complexes Sm(S2PPh2)3(THF)2 (1) and Sm(Se2PPh2)3(THF)2 (2) with soft-donor dithia- and diselenophosphinate ligands were synthesized and their photophysical properties were studied in detail. Both complexes displayed the metal-centered photoluminescence (PL) in visible and NIR regions corresponding to (4)G5/2→(6)HJ (J=5/2, 7/2, 9/2, 11/2, 13/2, 15/2), (6)FJ (J=1/2, 3/2, 5/2, 7/2, 9/2, 11/2) f-f transitions of Sm(3+). Luminescence decay curves exhibit an initial short build-up region and can be described by double or triple exponential function owing to multiphonon relaxation from the (4)F3/2 energy level to the (4)G5/2 one and reversible energy transfer from the Sm(3+) excited states to the triplet ((3)T1) state of phosphinate ligand. A Judd-Ofelt analysis was performed to estimate PL quantum efficiency (QE), branching ratios (β) and induced-emission cross section (σem) of the compounds obtained. It was found that the Judd-Ofelt parameter Ω2 of 1 is significantly greater than that of 2. This feature is responsible for large values of β (50.98%) and σem (4.29×10(-21)cm(2)) which suggest 1 as a good candidate for the development of samarium doped polymethylmethacrylate (PMMA) laser medium acting on the (4)G5/2→(6)H9/2 transition at 645nm. The estimated room-temperature PL QE of 1 and 2 equals to 1.9 and 0.17%, respectively. PMID:27045786

  12. Spectral Synthesis via Mean Field approach to Independent Component Analysis

    NASA Astrophysics Data System (ADS)

    Hu, Ning; Su, Shan-Shan; Kong, Xu

    2016-03-01

    We apply a new statistical analysis technique, the Mean Field approach to Independent Component Analysis (MF-ICA) in a Bayseian framework, to galaxy spectral analysis. This algorithm can compress a stellar spectral library into a few Independent Components (ICs), and the galaxy spectrum can be reconstructed by these ICs. Compared to other algorithms which decompose a galaxy spectrum into a combination of several simple stellar populations, the MF-ICA approach offers a large improvement in efficiency. To check the reliability of this spectral analysis method, three different methods are used: (1) parameter recovery for simulated galaxies, (2) comparison with parameters estimated by other methods, and (3) consistency test of parameters derived with galaxies from the Sloan Digital Sky Survey. We find that our MF-ICA method can not only fit the observed galaxy spectra efficiently, but can also accurately recover the physical parameters of galaxies. We also apply our spectral analysis method to the DEEP2 spectroscopic data, and find it can provide excellent fitting results for low signal-to-noise spectra.

  13. Metal complexes of ONO donor Schiff base ligand as a new class of bioactive compounds; Synthesis, characterization and biological evolution

    NASA Astrophysics Data System (ADS)

    Kumar Naik, K. H.; Selvaraj, S.; Naik, Nagaraja

    2014-10-01

    Present work reviews that, the synthesis of (E)-N";-((7-hydroxy-4-methyl-2-oxo-2H-chromen-8-yl)methylene)benzohydrazide [L] ligand and their metal complexes. The colored complexes were prepared of type [M2+L]X2, where M2+ = Mn, Co, Ni, Cu, Sr and Cd, L = (7-hydroxy-4-methyl-2-oxo-2H-chromen-8-yl)methylene)benzohydrazide, X = Cl-. Ligand derived from the condensation of 8-formyl-7-hydroxy-4-methylcoumarin and benzohydrazide in the molar ratio 1:1 and in the molar ratio 1:2 for metal complexes have been prepared. The chelation of the ligand to metal ions occurs through the both oxygen groups, as well as the nitrogen atoms of the azomethine group of the ligand. Reactions of the Schiff base ligand with Manganese(II), Cobalt(II), Nickel(II), Copper(II), Strontium(II), and Cadmium(II) afforded the corresponding metal complexes. The structures of the obtained ligand and their respective metal complexes were elucidated by infra-red, elemental analysis, Double beam UV-visible spectra, conductometric measurements, magnetic susceptibility measurements and also thermochemical studies. The metal complex exhibits octahedral coordination geometrical arrangement. Schiff base ligand and their metal complexes were tested against antioxidants, antidiabetic and antimicrobial activities have been studied. The Schiff base metal complexes emerges effective α-glucosidase inhibitory activity than free Schiff base ligand.

  14. Spectral synthesis of metallicity gradients in bright early-type galaxies

    NASA Astrophysics Data System (ADS)

    Couture, Jean; Hardy, Eduardo

    1990-02-01

    The main question posed in this investigation is whether spectral synthesis methods confirm the metallicity gradient suggested by the observed Mg2 gradients. To this end, the method of optimized spectral population synthesis is applied to spatially resolved spectroscopic data for a sample of six bright early-type galaxies. The data were obtained at Mont Megantic with a panoramic photon-counting system and cover the 4800-5500 A spectral interval and a spatial interval of more than one effective radius. An overall trend of decreasing metallicity with radial distance was found. The statistical significance of the mean metallicity gradient is consistent with the adopted Fe/H vs Mg2 calibration employed by Couture and Hardy (1988). The results lend confidence to the conclusion that Mg2 gradients are controlled mainly by metallicity. The requirements, limitations, and possible improvements of the method employed here are discussed.

  15. The Relation Between the Spectral Synthesis of Galaxies in the Visible Region and Their UV Emission

    NASA Astrophysics Data System (ADS)

    Dantas, M. L.; Sodré, L., Jr.

    2014-10-01

    The STARLIGHT Project has analyzed almost a million spectra extracted from the Sloan Digital Sky Survey (SDSS) by using the empirical spectral synthesis approach described by Cid Fernandes et al.(2005). Spectral synthesis consists on the optical spectrum fitting by using simple stellar population libraries, such as Bruzual & Charlot (2003). It also considers the reddening caused by dust and the velocity dispersion due to the motion of the stars within the galaxy. Since the model that best fits the optical region can also be extended to the ultraviolet, we compare our predictions to the UV photometry of the same galaxies measured by the GALEX satellite, studying the systematics and nature of the differences. In this current presentation, we show the upcoming challenges in order to accomplish this investigation. The main motivation of this study is to obtain realistic spectral models from the UV to the optical regions for the study of high redshift galaxies.

  16. Synthesis of unsymmetrical sulfides using ethyl potassium xanthogenate and recyclable copper catalyst under ligand-free conditions.

    PubMed

    Akkilagunta, Vijay Kumar; Kakulapati, Rama Rao

    2011-08-19

    The synthesis of unsymmetrical sulfides has been achieved in good to excellent yields with inexpensive ethyl potassium xanthogenate via cross-coupling reaction using recyclable CuO nanoparticles under ligand-free conditions.The copper oxide nanoparticles can be recovered and reused up to five cycles without loss of activity. PMID:21732640

  17. Ligand-controlled Co-reduction versus electroless Co-deposition: synthesis of nanodendrites with spatially defined bimetallic distributions.

    PubMed

    Ortiz, Nancy; Weiner, Rebecca G; Skrabalak, Sara E

    2014-12-23

    The predictable synthesis of bimetallic nanostructures via co-reduction of two metal precursors is challenging due to our limited understanding of precursor ligand effects. Here, the influence of different metal-ligand environments is systematically examined in the synthesis of Pd-Pt nanostructures as a model bimetallic system. Nanodendrites with different spatially defined Pd-Pt compositions are achieved, where the local ligand environments of metal precursors dictate if temporally separated co-reduction dominates to achieve core-shell nanostructures or whether electroless co-deposition proceeds to facilitate alloyed nanostructure formation. As the properties of bimetallic nanomaterials depend on crystal ordering and composition, chemical routes to structurally defined bimetallic nanomaterials are critically needed. The approaches reported here should be applicable to other bimetallic compositions given the established reactivity of coordination complexes available for use as precursors. PMID:25490676

  18. The Effective Temperature Scale of M Dwarfs from Spectral Synthesis

    NASA Astrophysics Data System (ADS)

    Reylé, C.; Rajpurohit, A. S.; Schultheis, M.; Allard, F.

    2011-12-01

    We present a comparison of low-resolution spectra of 60 stars covering the whole M-dwarf sequence. Using the most recent PHOENIX BT-Settl stellar model atmospheres (see paper by F. Allard, in this book) we do a first quantitative comparison to our observed spectra in the wavelength range 550-950 nm. We perform a first confrontation between models and observations and we assign an effective temperatures to the observed M-dwarfs. Teff-spectral type relations are then compared with the published ones. This comparison also aims at improving the models' opacities.

  19. Mixed ligand complexation of some transition metal ions in solution and solid state: Spectral characterization, antimicrobial, antioxidant, DNA cleavage activities and molecular modeling

    NASA Astrophysics Data System (ADS)

    Shobana, Sutha; Dharmaraja, Jeyaprakash; Selvaraj, Shanmugaperumal

    2013-04-01

    Equilibrium studies of Ni(II), Cu(II) and Zn(II) mixed ligand complexes involving a primary ligand 5-fluorouracil (5-FU; A) and imidazoles viz., imidazole (him), benzimidazole (bim), histamine (hist) and L-histidine (his) as co-ligands(B) were carried out pH-metrically in aqueous medium at 310 ± 0.1 K with I = 0.15 M (NaClO4). In solution state, the stoichiometry of MABH, MAB and MAB2 species have been detected. The primary ligand(A) binds the central M(II) ions in a monodentate manner whereas him, bim, hist and his co-ligands(B) bind in mono, mono, bi and tridentate modes respectively. The calculated Δ log K, log X and log X' values indicate higher stability of the mixed ligand complexes in comparison to binary species. Stability of the mixed ligand complex equilibria follows the Irving-Williams order of stability. In vitro biological evaluations of the free ligand(A) and their metal complexes by well diffusion technique show moderate activities against common bacterial and fungal strains. Oxidative cleavage interaction of ligand(A) and their copper complexes with CT DNA is also studied by gel electrophoresis method in the presence of oxidant. In vitro antioxidant evaluations of the primary ligand(A), CuA and CuAB complexes by DPPH free radical scavenging model were carried out. In solid, the MAB type of M(II)sbnd 5-FU(A)sbnd his(B) complexes were isolated and characterized by various physico-chemical and spectral techniques. Both the magnetic susceptibility and electronic spectral analysis suggest distorted octahedral geometry. Thermal studies on the synthesized mixed ligand complexes show loss of coordinated water molecule in the first step followed by decomposition of the organic residues subsequently. XRD and SEM analysis suggest that the microcrystalline nature and homogeneous morphology of MAB complexes. Further, the 3D molecular modeling and analysis for the mixed ligand MAB complexes have also been carried out.

  20. Synthesis, crystal structures and spectroscopic properties of cobalt(II) complexes with chelating sulfonylamidophosphate ligands

    NASA Astrophysics Data System (ADS)

    Znovjyak, Kateryna O.; Seredyuk, Maksym; Kusz, Joachim; Nowak, Maria; Moroz, Olesia V.; Sliva, Tetiana Yu; Amirkhanov, Vladimir M.

    2015-11-01

    Two new cobalt(II) complexes with general formula Co(L1)2Phen (1) and Co(L2)2Phen (2), in which HL1 = dimethyl phenylsulfonylphosphoramidate and HL2 = dimethyl tosylphosphoramidate, were prepared in one-step synthesis and characterized by IR, UV-VIS spectroscopy, TGA-DTA and elemental analysis. Moreover, the single crystal structures of 1 and 2 were determined by single crystal X-ray diffractometry. Complexes consist of mononuclear units comprising two L1-(or L2-) and phenanthroline ligands bidentatly linked to metal ion. The UV-VIS spectra of complexes in the solid state show broad asymmetric band at 530 nm attributed to the d-d transition of the metal ion. Comparing of these spectra with the absorption spectra in acetone, octahedral environment of the cobalt(II) ion in solution were considered. The structural similarity of 1 and 2 leads to a similar thermal decomposition profile.

  1. Multivalent ligand mimetics of LecA from P. aeruginosa: synthesis and NMR studies.

    PubMed

    Bini, Davide; Marchetti, Roberta; Russo, Laura; Molinaro, Antonio; Silipo, Alba; Cipolla, Laura

    2016-06-24

    Molecular recognition of glycans plays an important role in glycomic and glycobiology studies. For example, pathogens have a number of different types of lectin for targeting host sugars. In bacteria, lectins exist sometimes as domains of bacterial toxins and exploit adhesion to glycoconjugates as a means of entering host cells. Herein, we describe the synthesis of three glycodendrons with the aim to dissect the fine structural details involved in the multivalent carbohydrate-protein interactions. LecA, from the pathogen Pseudomonas aeruginosa, has been used to characterize galactose dendrons interaction using one of the most widespread NMR technique for the elucidation of receptor-ligand binding in solution, the saturation transfer difference (STD) NMR. Furthermore, the effective hydrodynamic radius of each dendrimer recognized by LecA was estimated from the diffusion coefficients determined by pulsed-field-gradient stimulated echo (PFG-STE) NMR experiments. PMID:27185108

  2. Spectral, electrochemical and molecular orbital studies on solvatochromic mixed ligand copper(II) complexes of malonate and diamine derivatives

    NASA Astrophysics Data System (ADS)

    Taha, Ali

    2003-04-01

    Solvatochromic mixed ligand complexes of copper(II) with malonate and diamine derivatives, Cu n(RMal)(diam) nXm (where n=1 or 2, m=1-4, RMal, malonic acid (H 2Mal), diethylmalonate (HDEtMal) or diethylethoxyethylenemalonate (DEtEMal), and diam, ethylenediamine (en), 1,3-propylenediamine (1,3-pn), N, N, N'-trimethylethylenediamine (Me 3en), N, N, N'-triethylethylenediamine (Et 3en), N, N, N', N'-tetramethylethylenediamine (Me 4en), N, N, N', N'-tetramethylpropylenediamine (Me 4pn), or N-methyl-1,4-diazacycloheptane (medach); and X=ClO 4- or Cl -), has been synthesized and characterized by spectroscopic, magnetic, molar conductance and electrochemical measurements. The mass spectra along with the analytical data of the complexes show peaks with m/ e corresponding to a bridged binuclear structure for the chloride complexes, while perchlorate complexes showed either mononuclear structure for DEtMal and DEtEMal or bridged binuclear structure for Mal complexes. These results correspond to IR spectral data, which indicated that the modes of ester and carboxylato coordination sites are mono- and/or bidentate. The d-d absorption bands in weak donor solvents suggest square-planar and distorted square pyramidal-trigonal bipyramid geometries for the perchlorate and chloride complexes; respectively. On the other hand, an octahedral structure is identified for complexes in strong donor solvents. Perchlorate complexes show a drastic color change from violet to green as the donation ability of solvent increases, whereas chloride complexes are highly affected by the acceptor properties of the solvent. Cyclic voltammetric measurements on the complexes, proposed a quasi-reversible or irreversible and mainly diffusion controlled reduction process. Such behavior has been explained according to the ECE mechanism. A linear correlation has been found between the Cu(II) reduction potential and the spectral data. Molecular orbital calculations were performed for the ligands on the bases of

  3. A facile synthesis of fluorescent silver nanoclusters with human ferritin as a synthetic and interfacing ligand.

    PubMed

    Lee, In Hwan; Ahn, Byungjun; Lee, Jeong Min; Lee, Chang Soo; Jung, Yongwon

    2015-05-21

    Water-soluble fluorescent silver nanoclusters (NCs) formed on biomolecule ligands have been extensively studied due to their great potential as new biocompatible fluorescent materials for biosensors. As synthetic ligands, proteins in particular can provide unique structures and functions to the assembled fluorescent silver clusters. A key challenge, however, is to develop appropriate protein ligands and synthetic approaches for cluster formation, especially using native aqueous solutions, to fully preserve the valuable properties of the protein templates. Here we report a human ferritin-templated synthesis of fluorescent silver NCs under neutral aqueous buffer conditions. The unique metal binding property of ferritin and an optimized silver ion reduction allowed us to produce highly stable fluorescent silver NCs that are steadily assembled in the cage-like ferritin proteins. The fluorescent clusters were also successfully assembled on genetically engineered ferritin with antibody-binding protein G. The resulting protein G-ferritin-silver NC complex fully retained the ferritin structure as well as the antibody binding ability. The present silver nanoclusters on ferritin (Ft-Ag NCs) also showed highly specific Cu(2+)-induced fluorescence quenching. By exploiting the large but stable nature of ferritin, we fabricated a highly robust and porous hydrogel sensor system for rapid Cu(2+) detection, where the Ft-Ag NCs were stably encapsulated in surface-bound hydrogels with large pore sizes. Our Ft-Ag NCs that are formed under native aqueous conditions will have great potential as a new fluorescent material with the high structural and functional diversities of ferritin. PMID:25848642

  4. A Selenium-Containing Diarylamido Pincer Ligand: Synthesis and Coordination Chemistry with Group 10 Metals.

    PubMed

    Charette, Bronte J; Ritch, Jamie S

    2016-06-20

    The synthesis of new bifunctional organoselenium diarylamine compounds RN(4-Me-2-SeMe-C6H3)2 (R = Me: 1; R = tert-butoxycarbonyl (Boc): 2; R = H: 3-H) via aryllithium chemistry is disclosed. Compound 1 serves as a Se,Se-bidentate neutral ligand toward Pd(II), forming the coordination complex {PdCl2[MeN(4-Me-2-SeMe-C6H3)2-κ(2)Se)]} (1-Pd) in reaction with [PdCl2(COD)] (COD = 1,5-cyclooctadiene), while the protio ligand 3-H forms tridentate pincer complexes [MCl(N(4-Me-2-SeMe-C6H3)2)] (M = Pd: 3-Pd; M = Pt: 3-Pt) with [MCl2(COD)] (M = Pd, Pt) in the presence of triethylamine. Complex 1-Pd does not undergo N-C cleavage at high temperature, unlike related alkylphosphine-bearing complexes. All compounds have been characterized by multinuclear ((1)H, (13)C, (77)Se) NMR spectroscopy, and crystal structures of 1, 1-Pd, 3-Pd, and 3-Pt are reported. Additionally, density functional theory calculations have been performed on the pincer complexes to contrast them with well-known analogues containing phosphine donor groups. PMID:27281450

  5. Design and synthesis of dual-ligand modified chitosan as a liver targeting vector.

    PubMed

    Chen, Houxiang; Li, Min; Wan, Tao; Zheng, Qichang; Cheng, Mingrong; Huang, Shiqi; Wang, Yong

    2012-02-01

    Vector plays an important role in hepatic targeted drug delivery system. In this study, a novel material as a liver targeting vector, dual-ligand modified chitosan (GCGA) composed of chitosan (CTS), glycyrrhetinic acid (GA) and lactobionic acid (LA), was designed and synthesized by an orthogonal experiment with two-step synthesis under mild conditions. The synthesized final product was characterized and confirmed by FTIR and (1)H-NMR spectroscopy, and DS of GA and LA in CTS were measured to be 13.77 and 16.74 mol% using (1)H-NMR, respectively. The cytotoxicity of CTS and GCGA was concentration dependent which was inverse proportion to the cell viability by MTT assay using L929 cell line, and inhibitory concentration 50% (IC50) was 0.2 mg/ml for GCGA. The in vitro targeting efficiency and the in vitro cellular uptake were investigated. Compared with CTS NPs and GA-CTS NPs, GCGA NPs showed good cell specificity to BEL-7402 cells via the dual-ligand-receptor-mediated recognition, leading to a higher affinity to BEL-7402 cells. The results suggested that GCGA described here has the potential to be used as an effective vector for hepatic targeted drug therapy. PMID:22105225

  6. New formamidine ligands and their mixed ligand palladium(II) oxalate complexes: Synthesis, characterization, DFT calculations and in vitro cytotoxicity

    NASA Astrophysics Data System (ADS)

    Soliman, Ahmed A.; Alajrawy, Othman I.; Attabi, Fawzy A.; Shaaban, Mohamed R.; Linert, W.

    2016-01-01

    A series of new ternary palladium(II) complexes of the type [Pd(L1-4)ox]·xH2O where L = formamidine ligands and ox = oxalate, were synthesized and characterized by elemental analyses, magnetic susceptibility, UV-Vis, infrared (IR) and mass spectroscopy and thermal analysis. The spectroscopic data indicated that the formamidine ligands act as bidentate N2 donors and the oxalate as O2 ligand. The complexes (1-4) are diamagnetic and the optimization of their structures indicated that the geometry is distorted square planer with O-Pd-O and N-Pd-N bond angles ranged 82.70-83.87° and 88.21-95.02°; respectively which is acceptable for the heteroleptic complexes. The dipole moment of the complexes (13.97-18.77 Debye) indicating that the complexes are more polarized than the ligands (1.93-4.96 Debye). The complexes are thermally stable as shown from their relatively higher overall activation energies (441-688 kJ mol-1). The ligands and the complexes are proved to have good cytotoxicity with IC50 (μM) in the range of (0.011-0.168) against MCF-7, (0.012-0.150) against HCT-116, (0.042-0.094) against PC-3 and (0.006-0.222) against HepG-2 cell lines, which open the field for further application as antitumor compounds.

  7. Modular solid-phase synthesis, catalytic application and efficient recycling of supported phosphine-phosphite ligand libraries.

    PubMed

    Heutz, Frank J L; Kamer, Paul C J

    2016-02-01

    In spite of decades of research in the field of homogeneous asymmetric catalysis the discovery of new high performance catalysts still relies heavily on trial-and-error. There is still a lack of efficient combinatorial methods which enable the synthesis and screening of vast ligand libraries, especially for bidentate phosphorus ligands. Here we present a highly modular solid-phase synthetic approach which provides facile access to libraries of phosphine-phosphite ligands in quantitative yield requiring only minimal work-up. The obtained library of supported phosphine-phosphites was successfully applied in rhodium catalyzed asymmetric hydrogenation obtaining high enantioselectivities up to 98%. Also, these polymer supported ligands could be successfully recycled under batch conditions exhibiting only a small decline of activity and no loss of selectivity. PMID:26486695

  8. Design of HIV-1 Protease Inhibitors with C3-Substituted Hexahydrocyclopentafuranyl Urethanes as P2-Ligands: Synthesis, Biological Evaluation, and Protein-Ligand X-ray Crystal Structure

    SciTech Connect

    Ghosh, Arun K; Chapsal, Bruno D; Parham, Garth L; Steffey, Melinda; Agniswamy, Johnson; Wang, Yuan-Fang; Amano, Masayuki; Weber, Irene T; Mitsuya, Hiroaki

    2011-11-07

    We report the design, synthesis, biological evaluation, and the X-ray crystal structure of a novel inhibitor bound to the HIV-1 protease. Various C3-functionalized cyclopentanyltetrahydrofurans (Cp-THF) were designed to interact with the flap Gly48 carbonyl or amide NH in the S2-subsite of the HIV-1 protease. We investigated the potential of those functionalized ligands in combination with hydroxyethylsulfonamide isosteres. Inhibitor 26 containing a 3-(R)-hydroxyl group on the Cp-THF core displayed the most potent enzyme inhibitory and antiviral activity. Our studies revealed a preference for the 3-(R)-configuration over the corresponding 3-(S)-derivative. Inhibitor 26 exhibited potent activity against a panel of multidrug-resistant HIV-1 variants. A high resolution X-ray structure of 26-bound HIV-1 protease revealed important molecular insight into the ligand-binding site interactions.

  9. Self assembled homodinuclear dithiocarbamates: one pot synthesis and spectral characterization.

    PubMed

    Nami, Shahab A A; Husain, Ahmad; Ullah, Irfan

    2014-01-24

    Several self assembled homodinuclear complexes of the type [M2(Ldtc)2·4H2O] derived from quadridentate ligand (Ldtc), where Ldtc = 2-aminobenzoylhydrazidebis(dithiocarbamate) and M = Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II) have been reported. The in situ procedure gives high yield with the formation of single product as evident by TLC and various other physicochemical techniques. Elemental analysis, TGA, (1)H NMR, (13)C NMR, ESI mass spectrometry, EPR, UV-vis. and IR spectroscopy were used to characterize the homodinuclear complexes. The spectroscopic evidences and room temperature magnetic moment values suggest that all the complexes have octahedral geometry around the transition metal atom. A symmetrical bidentate coordination of the dithiocarbamato moiety has been observed in all the complexes. The energy-minimized structure of the molecule also showed that each metal atom acquires a distorted octahedral geometry. The complexes exhibit a three-step thermolytic pattern and are non-electrolyte in nature. PMID:24064153

  10. Self assembled homodinuclear dithiocarbamates: One pot synthesis and spectral characterization

    NASA Astrophysics Data System (ADS)

    Nami, Shahab A. A.; Husain, Ahmad; Ullah, Irfan

    2014-01-01

    Several self assembled homodinuclear complexes of the type [M2(Ldtc)2·4H2O] derived from quadridentate ligand (Ldtc), where Ldtc = 2-aminobenzoylhydrazidebis(dithiocarbamate) and M = Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II) have been reported. The in situ procedure gives high yield with the formation of single product as evident by TLC and various other physicochemical techniques. Elemental analysis, TGA, 1H NMR, 13C NMR, ESI mass spectrometry, EPR, UV-vis. and IR spectroscopy were used to characterize the homodinuclear complexes. The spectroscopic evidences and room temperature magnetic moment values suggest that all the complexes have octahedral geometry around the transition metal atom. A symmetrical bidentate coordination of the dithiocarbamato moiety has been observed in all the complexes. The energy-minimized structure of the molecule also showed that each metal atom acquires a distorted octahedral geometry. The complexes exhibit a three-step thermolytic pattern and are non-electrolyte in nature.

  11. Synthesis, spectral, computational and thermal analysis studies of metalloceftriaxone antibiotic

    NASA Astrophysics Data System (ADS)

    Masoud, Mamdouh S.; Ali, Alaa E.; Elasala, Gehan S.

    2015-03-01

    Binary ceftriaxone metal complexes of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Hg(II) and six mixed metals complexes of (Fe, Cu), (Fe, Co), (Co, Ni), (Co, Cu), (Ni, Cu) and (Fe, Ni) were synthesized and characterized by elemental analysis, IR, electronic spectra, magnetic susceptibility and ESR spectra. The studies proved that the ligand has different combination modes and all complexes were of octahedral geometry. Molecular modeling techniques and quantum chemical methods have been performed for ceftriaxone to calculate charges, bond lengths, bond angles, dihedral angles, electronegativity (χ), chemical potential (μ), global hardness (η), softness (σ) and the electrophilicity index (ω). The thermal decomposition of the prepared metals complexes was studied by TGA, DTA and DSC techniques. The kinetic parameters and the reaction orders were estimated. The thermal decomposition of all the complexes ended with the formation of metal oxides and carbon residue as a final product except in case of Hg complex, sublimation occurs at the temperature range 297.7-413.7 °C so, only carbon residue was produced during thermal decomposition. The geometries of complexes may be altered from Oh to Td during the thermal decomposition steps. Decomposition mechanisms were suggested.

  12. Synthesis, structure, photophysical and catalytic properties of CuI-Iodide complexes of di-imine ligands

    NASA Astrophysics Data System (ADS)

    Mondal, Jahangir; Ghorai, Anupam; Singh, Sunil K.; Saha, Rajat; Patra, Goutam K.

    2016-03-01

    Two new multifunctional CuII based complexes [CuI(L1)] (1) and [Cu2(μ-I)2(L2)] (2) with bidentate N-N donor ligands L1 and imino-pyridyl ligand L2 have been synthesized and characterized by elemental analysis, IR, UV-Vis, NMR and single crystal X-ray crystallography. The bidentate di-imine ligand (L1) forms monomeric CuI complex (1) whereas the bis-bidentate di-imine ligand (L2) favours the formation of dimeric CuI complex (2) in association with two bridging iodides. Structural analysis reveals that in complex 1 each monomeric units are connected by π⋯π and C-H⋯π interactions to form 3D supramolecular structure whereas in complex 2 each molecules are connected by only π⋯π interactions to form 3D supramolecular structure. The photoluminescence properties of the complexes have been studied at room temperature. Theoretical analysis shows that HOMO is focused on the Cu and iodides while LUMO is focused on di-imine ligands and the luminescence behaviour arises due to metal to ligand charge transfer (MLCT) and halide to ligand charge transfer (XLCT). The complexes 1 and 2 are effective catalysts for the synthesis of 2-substituted benzoxazoles.

  13. Spiro-fused carbohydrate oxazoline ligands: Synthesis and application as enantio-discrimination agents in asymmetric allylic alkylation.

    PubMed

    Kraft, Jochen; Golkowski, Martin; Ziegler, Thomas

    2016-01-01

    In the present work, we describe a convenient synthesis of spiro-fused D-fructo- and D-psico-configurated oxazoline ligands and their application in asymmetric catalysis. The ligands were synthesized from readily available 3,4,5-tri-O-benzyl-1,2-O-isopropylidene-β-D-fructopyranose and 3,4,5-tri-O-benzyl-1,2-O-isopropylidene-β-D-psicopyranose, respectively. The latter compounds were partially deprotected under acidic conditions followed by condensation with thiocyanic acid to give an anomeric mixture of the corresponding 1,3-oxazolidine-2-thiones. The anomeric 1,3-oxazolidine-2-thiones were separated after successive benzylation, fully characterized and subjected to palladium catalyzed Suzuki-Miyaura coupling with 2-pyridineboronic acid N-phenyldiethanolamine ester to give the corresponding 2-pyridyl spiro-oxazoline (PyOx) ligands. The spiro-oxazoline ligands showed high asymmetric induction (up to 93% ee) when applied as chiral ligands in palladium-catalyzed allylic alkylation of 1,3-diphenylallyl acetate with dimethyl malonate. The D-fructo-PyOx ligand provided mainly the (R)-enantiomer while the D-psico-configurated ligand gave the (S)-enantiomer with a lower enantiomeric excess. PMID:26877819

  14. Spiro-fused carbohydrate oxazoline ligands: Synthesis and application as enantio-discrimination agents in asymmetric allylic alkylation

    PubMed Central

    Kraft, Jochen; Golkowski, Martin

    2016-01-01

    Summary In the present work, we describe a convenient synthesis of spiro-fused D-fructo- and D-psico-configurated oxazoline ligands and their application in asymmetric catalysis. The ligands were synthesized from readily available 3,4,5-tri-O-benzyl-1,2-O-isopropylidene-β-D-fructopyranose and 3,4,5-tri-O-benzyl-1,2-O-isopropylidene-β-D-psicopyranose, respectively. The latter compounds were partially deprotected under acidic conditions followed by condensation with thiocyanic acid to give an anomeric mixture of the corresponding 1,3-oxazolidine-2-thiones. The anomeric 1,3-oxazolidine-2-thiones were separated after successive benzylation, fully characterized and subjected to palladium catalyzed Suzuki–Miyaura coupling with 2-pyridineboronic acid N-phenyldiethanolamine ester to give the corresponding 2-pyridyl spiro-oxazoline (PyOx) ligands. The spiro-oxazoline ligands showed high asymmetric induction (up to 93% ee) when applied as chiral ligands in palladium-catalyzed allylic alkylation of 1,3-diphenylallyl acetate with dimethyl malonate. The D-fructo-PyOx ligand provided mainly the (R)-enantiomer while the D-psico-configurated ligand gave the (S)-enantiomer with a lower enantiomeric excess. PMID:26877819

  15. Synthesis, reaction and structure of a series of chromium(III) complexes containing oxalate ligand

    NASA Astrophysics Data System (ADS)

    Chen, Xu-Fang; Liu, Li; Ma, Jian-Gong; Yi, Long; Cheng, Peng; Liao, Dai-Zheng; Yan, Shi-Ping; Jiang, Zong-Hui

    2005-08-01

    A series of chromium(III) complexes [Cr(bipy)(HC2O4)2]Cl·3H2O (1), [Cr(phen)(HC2O4)2]Cl·3H2O (2), [Cr(phen)2(C2O4)]ClO4 (3), [Cr2(bipy)4(C2O4)](SO4)·(bipy)0.5·H2O (4) and [Mn(phen)2(H2O)2]2[Cr(phen)(C2O4)2]3ClO4·14H2O (5) were synthesized (bipy=4,4‧-bipyridine, phen=1,10-phenanthroline), while the crystal structures of 1 and 3-5 have been determined by X-ray analysis. 1 and 3 are mononuclear complexes, 4 contains binuclear chromium(III) ions and 5 is a 3D supromolecule formed by complicated hydrogen bonding. 1-3 are potential molecular bricks of chromium(III) building blocks for synthesis heterometallic complexes. When we use these molecular bricks as ligands to react with other metal salts, unexpected complexes 4 and 5 are isolated in water solution. The synthesis conditions and reaction results are also discussed.

  16. Amide Coupling Reaction for the Synthesis of Bispyridine-based Ligands and Their Complexation to Platinum as Dinuclear Anticancer Agents

    PubMed Central

    Apps, Michael G.; Johnson, Ben W.; Sutcliffe, Oliver B.; Brown, Sarah D.; Wheate, Nial J.

    2014-01-01

    Amide coupling reactions can be used to synthesize bispyridine-based ligands for use as bridging linkers in multinuclear platinum anticancer drugs. Isonicotinic acid, or its derivatives, are coupled to variable length diaminoalkane chains under an inert atmosphere in anhydrous DMF or DMSO with the use of a weak base, triethylamine, and a coupling agent, 1-propylphosphonic anhydride. The products precipitate from solution upon formation or can be precipitated by the addition of water. If desired, the ligands can be further purified by recrystallization from hot water. Dinuclear platinum complex synthesis using the bispyridine ligands is done in hot water using transplatin. The most informative of the chemical characterization techniques to determine the structure and gross purity of both the bispyridine ligands and the final platinum complexes is 1H NMR with particular analysis of the aromatic region of the spectra (7-9 ppm). The platinum complexes have potential application as anticancer agents and the synthesis method can be modified to produce trinuclear and other multinuclear complexes with different hydrogen bonding functionality in the bridging ligand. PMID:24893964

  17. Synthesis and spectral characterization of environmentally responsive fluorescent deoxycytidine analogs

    PubMed Central

    Elmehriki, Adam AH; Suchý, Mojmír; Chicas, Kirby J; Wojciechowski, Filip; Hudson, Robert HE

    2014-01-01

    Herein, we describe the synthesis and spectroscopic properties of five novel pyrrolodeoxycytidine analogs, and the related 5-(1-pyrenylethynyl)-2’-deoxycytidine analog; as well as fluorescence characterization of 5-(p-methoxyphenylethynyl)-2’-deoxyuridine. Within this series of compounds, rigidification of the structure from 6-phenylpyrrolodeoxycytidine to 5,6-benzopyrroldeoxycytidine made remarkable improvement of the fluorescence quantum yield (Φ ~1, EtOH) and substantially increased the Stokes shift. Exchange of the phenyl group of 6-phenylpyrrolodeoxycytidine for other heterocycles (benzofuryl or indolyl) produced an increase in the extinction coefficient at the excitation wavelength while preserving high quantum yields. The steady-state fluorescence response to the environment was determined by sensitivity of Stokes shift to solvent polarity. The effect of solvent polarity on fluorescence emission intensity was concurrently examined and showed that 5,6-benzopyrrolodeoxycytidine is highly sensitive to the presence of water. On the other hand, the previously synthesized 5-(p-methoxyphenylethynyl)-2’-deoxyuridine was found to be sensitive to solvent viscosity indicating molecular rotor behavior. PMID:25483932

  18. Ruthenium(II) hydrazone Schiff base complexes: Synthesis, spectral study and catalytic applications

    NASA Astrophysics Data System (ADS)

    Manikandan, R.; Viswanathamurthi, P.; Muthukumar, M.

    2011-12-01

    Ruthenium(II) hydrazone Schiff base complexes of the type [RuCl(CO)(B)(L)] (were B = PPh 3, AsPh 3 or Py; L = hydrazone Schiff base ligands) were synthesized from the reactions of hydrazone Schiff base ligand (obtained from isonicotinoylhydrazide and different hydroxy aldehydes) with [RuHCl(CO)(EPh 3) 2(B)] (where E = P or As; B = PPh 3, AsPh 3 or Py) in 1:1 molar ratio. All the new complexes have been characterized by analytical and spectral (FT-IR, electronic, 1H, 13C and 31P NMR) data. They have been tentatively assigned an octahedral structure. The synthesized complexes have exhibited catalytic activity for oxidation of benzyl alcohol to benzaldehyde and cyclohexanol to cyclohexanone in the presence of N-methyl morpholine N-oxide (NMO) as co-oxidant. They were also found to catalyze the transfer hydrogenation of aliphatic and aromatic ketones to alcohols in KOH/Isopropanol.

  19. Synthesis and Characterization of Privileged Monodentate Phosphoramidite Ligands and Chiral Brønsted Acids Derived from d-Mannitol

    PubMed Central

    Al-Majid, Abdullah Mohammed A.; Barakat, Assem; Mabkhot, Yahia Nasser; Islam, Mohammad Shahidul

    2012-01-01

    The synthesis of several novel chiral phosphoramidite ligands (L1–L8) with C2 symmetric, pseudo C2 symmetric secondary amines and chiral Brønsted acids 1a,b has been achieved. These chiral auxiliaries were obtained from commercially available d-mannitol, and secondary amines in moderate to excellent yields. Excellent diastereoselectivites of ten chiral auxiliaries were obtained. The chiral phosphoramidite ligands and chiral Brønsted acids were fully characterized by spectroscopic methods. PMID:22489121

  20. Mn(II) and Cu(II) complexes of a bidentate Schiff's base ligand: Spectral, thermal, molecular modelling and mycological studies

    NASA Astrophysics Data System (ADS)

    Tyagi, Monika; Chandra, Sulekh; Tyagi, Prateek

    2014-01-01

    Complexes of manganese(II) and copper(II) of general composition M(L)2X2 have been synthesized [L = 2-acetyl thiophene thiosemicarbazone and X = Cl- and NO3-]. The elemental analysis, molar conductance measurements, magnetic susceptibility measurements, mass, IR, UV, NMR and EPR spectral studies of the compounds led to the conclusion that the ligand acts as a bidentate manner. The Schiff's base ligand forms hexacoordinated complexes having octahedral geometry for Mn(II) and tetragonal geometry for Cu(II) complexes. The thermal studies suggested that the complexes are more stable as compared to ligand. In molecular modelling the geometries of Schiff's base and metal complexes were fully optimized with respect to the energy using the 6-31g(d,p) basis set. The mycological studies of the compounds were examined against the plant pathogenic fungi i.e. Rhizoctonia bataticola, Macrophomina phaseolina, Fusarium odum.

  1. Design and synthesis of novel bivalent ligands (MOR and DOR) by conjugation of enkephalin analogues with 4-anilidopiperidine derivatives.

    PubMed

    Deekonda, Srinivas; Wugalter, Lauren; Rankin, David; Largent-Milnes, Tally M; Davis, Peg; Wang, Yue; Bassirirad, Neemah M; Lai, Josephine; Kulkarni, Vinod; Vanderah, Todd W; Porreca, Frank; Hruby, Victor J

    2015-10-15

    We describe the design and synthesis of novel bivalent ligands based on the conjugation of 4-anilidopiperidine derivatives with enkephalin analogues. The design of non-peptide analogues is explored with 5-amino substituted (tetrahydronaphthalen-2yl) methyl containing 4-anilidopiperidine derivatives, while non-peptide-peptide ligands are explored by conjugating the C-terminus of enkephalin analogues (H-Xxx-DAla-Gly-Phe-OH) to the amino group of 4-anilidopiperidine small molecule derivatives with and without a linker. These novel bivalent ligands are evaluated for biological activities at μ and δ opioid receptors. They exhibit very good affinities at μ and δ opioid receptors, and potent agonist activities in MVD and GPI assays. Among these the lead bivalent ligand 17 showed excellent binding affinities (0.1 nM and 0.5 nM) at μ and δ opioid receptors respectively, and was found to have very potent agonist activities in MVD (56 ± 5.9 nM) and GPI (4.6 ± 1.9 nM) assays. In vivo the lead bivalent ligand 17 exhibited a short duration of action (<15 min) comparable to 4-anilidopiperidine derivatives, and moderate analgesic activity. The ligand 17 has limited application against acute pain but may have utility in settings where a highly reversible analgesic is required. PMID:26323872

  2. New divalent manganese complex with pyridine carboxylate N-oxide ligand: Synthesis, structure and magnetic properties

    SciTech Connect

    Liu Fuchen; Xue Min; Wang Haichao; Ouyang Jie

    2010-09-15

    Two new manganese complexes, [Mn{sub 3}(L{sup 1}){sub 4}(NO{sub 3}){sub 2}]{sub n} (1, HL{sup 1}=nicotinate N-oxide acid) and [MnL{sup 2}Cl]{sub n} (2, HL{sup 2}=isonicotinate N-oxide acid)], have been hydrothermally synthesized and characterized by elemental analysis, IR and single-crystal X-ray diffraction. In 1, the L{sup 1} ligands take two different coordinated modes bridging four and three Mn{sup II} ions. The nitrate anions take chelating coordination modes, leading one type of the Mn{sup II} ions as a 4-connected node. The whole net can be viewed as a 3, 4, 6-connected 4-nodal net with Schlaefli notation {l_brace}4{sup 3{r_brace}}2{l_brace}4{sup 4}; 6{sup 2{r_brace}}4{l_brace}4{sup 6}; 6{sup 6}; 8{sup 3{r_brace}}. Complex 2 has a honeycomb layer mixed bridged by chlorine, N-oxide and carboxylate. The adjacent layers are linked by the phenyl ring of L{sup 2} ligand, giving a 3D framework with a {l_brace}3{sup 4}; 5{sup 4{r_brace}} {l_brace}3{sup 2};4;5{sup 6};6{sup 6{r_brace}} 4, 6-connect net. Magnetic studies indicate that 1 is an antiferromagnet with low-dimensional characteristic, in which a -J{sub 1}J{sub 1}J{sub 2}- coupled alternating chain is predigested. Fitting the data of 1 gives the best parameters J{sub 1}=-2.77, J{sub 2}=-0.67 cm{sup -1}. The magnetic properties of complex 2 represent the character of the 2D honeycomb layer with the J{sub 1}=-2.05 and J{sub 2}=0.55 cm{sup -1}, which results in a whole antiferromagnetic state. - Graphical abstract: The synthesis, crystal structure and magnetic properties of two new MnII complexes with pyridyl-carboxylate N-oxide ligands are reported.

  3. Bio-relevant complexes of novel N2O2 type heterocyclic ligand: Synthesis, structural elucidation, biological evaluation and docking studies.

    PubMed

    Arun, T; Packianathan, S; Malarvizhi, M; Antony, R; Raman, N

    2015-08-01

    Organic and inorganic entities [Cu(II), Co(II), Ni(II) and Zn(II)] have been bridged by N2O2 type heterocyclic imine (CN) ligand for the synthesis of novel organic-inorganic bridged complexes of the type [M(H2L)]. The synthesized complexes were characterized by spectral techniques such as FT-IR, UV-visible, (1)H NMR, (13)C NMR, EPR, ESI-Mass, elemental analysis, magnetic susceptibility and molar conductivity measurements. The metal complexes adopt square planar geometrical arrangement around the metal ions. DNA binding ability of these complexes has been explored by different techniques viz. electronic absorption, fluorescence, cyclic voltammetry, differential pulse voltammetry and viscosity measurements. These studies prove that CT DNA interaction of the complexes follows intercalation mode. The oxidative cleavage of the complexes with pUC19 DNA has been investigated by gel electrophoresis. Molecular docking calculations have been performed to understand the nature of binding of the complexes with DNA. Moreover, the anti-pathogenic actions of the complexes were tested in vitro against few bacteria and fungi by disk diffusion method. The data reveal that the complexes have higher anti-pathogenic activity than the ligand. PMID:26057019

  4. New Synthesis and Tritium Labeling of a Selective Ligand for Studying High-affinity γ-Hydroxybutyrate (GHB) Binding Sites

    PubMed Central

    Vogensen, Stine B.; Marek, Aleš; Bay, Tina; Wellendorph, Petrine; Kehler, Jan; Bundgaard, Christoffer; Frølund, Bente; Pedersen, Martin H.F.; Clausen, Rasmus P.

    2013-01-01

    3-Hydroxycyclopent-1-enecarboxylic acid (HOCPCA, 1) is a potent ligand for the high-affinity GHB binding sites in the CNS. An improved synthesis of 1 together with a very efficient synthesis of [3H]-1 is described. The radiosynthesis employs in situ generated lithium trimethoxyborotritide. Screening of 1 against different CNS targets establishes a high selectivity and we demonstrate in vivo brain penetration. In vitro characterization of [3H]-1 binding shows high specificity to the high-affinity GHB binding sites. PMID:24053696

  5. Synthesis and structural characterization of two half-sandwich nickel(II) complexes with the scorpionate ligands

    SciTech Connect

    Wang, G.-F. E-mail: s-shuwen@163.com; Zhang, X.; Sun, S.-W.; Sun, H.; Ma, H.-X.

    2015-12-15

    The synthesis and characterization of two new halfsandwich mononuclear nickel(II) complexes with the scorpionate ligands, [k{sup 3}-N, N',N''-Tp{sup t-Bu}, {sup Me}NiI] (1) and [k{sup 3}-N,N',N''-Tp{sup t-Bu}, {sup Me}NiNO{sub 3}] (2), are reported. These complexes have been fully characterized by elemental analyses and infrared spectra. Their molecular structures were determined by single crystal X-ray diffraction. The nickel(II) ion of complex 1 is in a four-coordinate environment, in which the donor atoms are provided by three nitrogen atoms of a hydrotris(pyrazolyl) borate ligand and one iodide atom, while that of complex 2 is in a five-coordinate environment with three nitrogen atoms from a hydrotris(pyrazolyl)borate ligand and two oxygen atoms from a nitrate ion.

  6. Synthesis and characterisation of a novel mixed donor P,O,P' nixantphos ligand and its metal complex

    NASA Astrophysics Data System (ADS)

    Marimuthu, Thashree; Bala, Muhammad D.; Friedrich, Holger B.

    2016-02-01

    The complex [(NixC8OH)Ir(cod)Cl] 4 has been synthesized and structurally characterized by NMR, IR and single crystal X-ray diffraction. The synthesis and characterisation of the novel ligand NixC8OH is also presented. The coordination around Ir is trigonal bipyramidal with both P groups of the NixC8OH ligand bound in a bis-equatorial mode. The bis-chelating cod (C8H12) ligand occupies the remaining equatorial position and an axial position. This mode of bonding has resulted in a large bite angle (P1-Ir-P2) of 102.92(12)° for the title complex 4. The IR and NMR data further support the elucidated structure. Thermal analyses of 4 indicate that it is thermally stable up to a decomposition temperature of >400 °C.

  7. Synthesis and structural characterization of two half-sandwich nickel(II) complexes with the scorpionate ligands

    NASA Astrophysics Data System (ADS)

    Wang, G.-F.; Zhang, X.; Sun, S.-W.; Sun, H.; Ma, H.-X.

    2015-12-01

    The synthesis and characterization of two new halfsandwich mononuclear nickel(II) complexes with the scorpionate ligands, [ k 3- N, N', N''- Tp t-Bu, Me NiI] ( 1) and [ k 3- N, N', N''- Tp t-Bu, Me NiNO3] ( 2), are reported. These complexes have been fully characterized by elemental analyses and infrared spectra. Their molecular structures were determined by single crystal X-ray diffraction. The nickel(II) ion of complex 1 is in a four-coordinate environment, in which the donor atoms are provided by three nitrogen atoms of a hydrotris(pyrazolyl) borate ligand and one iodide atom, while that of complex 2 is in a five-coordinate environment with three nitrogen atoms from a hydrotris(pyrazolyl)borate ligand and two oxygen atoms from a nitrate ion.

  8. Recent developments in the synthesis and utilization of chiral β-aminophosphine derivatives as catalysts or ligands.

    PubMed

    Li, Wenbo; Zhang, Junliang

    2016-03-14

    In the last few years, the research area of chiral β-aminophosphines capable of promoting a wide range of diverse organic transformations has attracted more attention. Their derivatives constitute attractive reagents towards this end, due to their stability, low toxicity and ease of handling. These novel β-aminophosphine derivatives are potentially useful as organocatalysts and ligands in metal-catalysed reactions. In particular, chiral β-aminophosphines have recently emerged as powerful phosphine catalysts in asymmetric synthesis and catalysis. The asymmetric transformations to which metal complexes of these ligands have been applied include palladium-catalysed allylic substitutions and copper-catalysed 1,4-additions to enones among others. This review summarizes the most significant developments in the area of synthesis and application of chiral β-aminophosphine derivatives, providing a detailed overview of the current state of the art and including future aspects. PMID:26776280

  9. meso-Phenyltetrabenzotriazaporphyrin based double-decker lanthanide(III) complexes: synthesis, structure, spectral properties and electrochemistry.

    PubMed

    Pushkarev, Victor E; Kalashnikov, Valery V; Tolbin, Alexander Yu; Trashin, Stanislav A; Borisova, Nataliya E; Simonov, Sergey V; Rybakov, Victor B; Tomilova, Larisa G; Zefirov, Nikolay S

    2015-10-01

    A series of half-sandwich and sandwich-type lanthanide(III) complexes have been prepared using tetrabenzotriazaporphyrin ligands. Reaction of 27-phenyl-29H,31H-tetrabenzo[b,g,l,q][5,10,15]-triazaporphyrin (PhTBTAPH2, 1) with salts [LnX3]·nH2O (Ln = Eu (a), Lu (b); X = OAc, acac) afforded the single- and homoleptic double-deckers (PhTBTAP)LnOAc (2) and (PhTBTAP)2Ln (3) respectively. Heteroleptic double-decker compounds (PhTBTAP)LnPc (4a,b) were obtained upon interaction of 1 with the corresponding Ln mono(phthalocyaninates). An unexpected formation of partially and completely dephenylated co-products 5 and 6 has been detected in the synthesis of sandwich 3, while the possibility of the dearylation of the half-sandwich compound 2 has been demonstrated as well. A more predictable yet firstly observed formation of the triple-decker compound (PhTBTAP)3Eu2 (7) has also been found. Structural studies of 3 supported by 1H NMR spectra, XRD analysis and DFT theoretical calculations reveal that the Eu complex 3a is formed as a single isomer, while the lutetium compound 3b represents an inseparable mixture of two rotational isomers with virtually identical spectral characteristics. The double-decker compounds 3 and 4 reveal intrinsic UV-Vis/NIR absorption as well as peculiar electrochromic behavior. The heteroleptic derivatives 4 generally show intermediate spectral and electrochemical properties with respect to their homoleptic relatives. PMID:26332086

  10. Synthesis of binuclear platinum complexes containing the ligands 8-naphthyridine, 2-aminopyridine, and 7-azaindolate. An experimental study of the steric hindrance of the bulky pentafluorophenyl ligands in the synthesis of binuclear complexes.

    PubMed

    Casas, José M; Diosdado, Beatriz E; Forniés, Juan; Martín, Antonio; Rueda, Angel J; Orpen, A Guy

    2008-10-01

    The bidentate N-donor ligands 2-aminopyridine (2-ampy), 7-azaindolate (aza) and 1,8-naphthyridine (napy) have been used to study the steric effect of pentafluorophenyl groups in the synthesis of binuclear platinum(II) complexes. The 2-ampy and aza ligands bridge two "Pt(C 6F 5) 2" fragments with Pt...Pt distances of 4.1 and 3.4 A, respectively (complexes 1 and 3). Under the same reaction conditions the napy ligand shows chelating behavior and makes the mononuclear complex ( A) highly reactive because of its strained coordination. One of the Pt-N bonds of the chelating complex is broken on reaction with HX {X = Cl ( 4), Br ( 5)} because of protonation while the anion X (-) occupies a created vacant site. The resulting mononuclear complex eliminates C 6F 5H when refluxed, and a binuclear complex ( 6) with two napy ligands bridging two "Pt(C 6F 5)Cl" fragments is obtained. The reaction of A with HPPh 2 affords a mononuclear complex ( 7) analogous to complexes 5 and 6, but reflux gives a binuclear complex ( 8) with the two napy ligands terminally bound and the PPh 2 groups bridging the "Pt(C 6F 5)napy" moieties. The reaction of A with HCCPh gives a binuclear complex; moreover, the final product does not depend on the ratio of complex A to HCCPh. Complexes 1, 4, 6, 9 have been structurally characterized by X-ray diffraction. PMID:18767797

  11. Catalytic Borylative Opening of Propargyl Cyclopropane, Epoxide, Aziridine, and Oxetane Substrates: Ligand Controlled Synthesis of Allenyl Boronates and Alkenyl Diboronates.

    PubMed

    Zhao, Jian; Szabó, Kálmán J

    2016-01-22

    A new copper-catalyzed reaction for the stereo- and regioselective synthesis of alkenyl diboronates and allenyl boronates is presented. In this process propargyl derivatives of strained three/four-membered rings were employed as substrates and B2pin2 was used as the boronate source. Selective formation of the alkenyl diboronate versus the allenyl boronate products was controlled by the choice of phosphine ligand. PMID:26663468

  12. Catalytic Borylative Opening of Propargyl Cyclopropane, Epoxide, Aziridine, and Oxetane Substrates: Ligand Controlled Synthesis of Allenyl Boronates and Alkenyl Diboronates

    PubMed Central

    Zhao, Jian

    2015-01-01

    Abstract A new copper‐catalyzed reaction for the stereo‐ and regioselective synthesis of alkenyl diboronates and allenyl boronates is presented. In this process propargyl derivatives of strained three/four‐membered rings were employed as substrates and B2pin2 was used as the boronate source. Selective formation of the alkenyl diboronate versus the allenyl boronate products was controlled by the choice of phosphine ligand. PMID:26663468

  13. Pd-catalyzed asymmetric allylic etherification using chiral biphenol-based diphosphinite ligands and its application for the formal total synthesis of (-)-galanthamine.

    PubMed

    Zang, Yang; Ojima, Iwao

    2013-04-19

    A library of novel chiral biphenol-based diphosphinite (BOP) ligands was designed and created. These BOP ligands were applied to a Pd-catalyzed intermolecular allylic etherification reaction, which provided a key intermediate for the formal total synthesis of (-)-galanthamine with 97% ee in 97% yield. PMID:23472673

  14. New insights into the kinetic target-guided synthesis of protein ligands.

    PubMed

    Oueis, Emilia; Sabot, Cyrille; Renard, Pierre-Yves

    2015-08-01

    The kinetic target-guided synthesis (KTGS) strategy is an unconventional discovery approach that takes advantage of the presence of the biological target itself in order to irreversibly assemble the best inhibitors from an array of building blocks. This strategy has grown over the last two decades notably after the introduction of the in situ click chemistry concept by Sharpless and colleagues in the early 2000s based on the use of the Huisgen cycloaddition between terminal alkynes and azides. KTGS is a captivating area of research offering an unprecedented and powerful strategy to probe the macromolecular complexity and dynamics of biological targets. After a brief introduction listing all chemical ligation reactions reported to date in KTGS, this review focuses on the last five years' progress to expand the repertoire of the click or "click-like" tool box targeting proteins, as well as to overcome limitations arising in particular from false negatives, i.e. potent ligands that are not formed, or formed in undetectable trace amounts. Furthermore, we wish to analyze the new twists and novelties described in some of these applications in order to better understand the conditions that govern this strategy and the extent to which it can be developed and generalized for a more efficient process. PMID:26144842

  15. Synthesis and crystal structure of three mixed-ligand copper(II) complexes with nitrilotriacetic acid

    SciTech Connect

    Polyakova, I. N. Sergienko, V. S.; Poznyak, A. L.

    2006-05-15

    The synthesis and X-ray diffraction study of three Ca[CuX(Nta)] . 2H{sub 2}O complexes, where X = Cl (I) or Br (II and III are the monoclinic and orthorhombic modifications, respectively), are performed. Structures I-III are built of [CuX(Nta)]{sup 2-} anionic complexes and hydrated Ca{sup 2+} cations, which are linked by Ca-O bonds into a three-dimensional framework. In I-III, the coordination of the Cu atom includes the N atom and three O atoms of the tetradentate chelate Nta{sup 3-} ligand and the X{sup -} anion in the trans position with respect to N. The Cu-O bond lengths vary in the ranges 1.971-2.268 A in I, 1.958-2.289 A in II, and 2.040-2.110 A in III. The Cu-X bond lengths are 2.223, 2.364, and 2.354 A in I, II, and III, respectively. In I and II, the coordination polyhedron of the Cu atom is approximated by a distorted square pyramid with an O atom at the apical vertex, whereas in III, the polyhedron is described as a distorted trigonal bipyramid with the N and Br atoms at the axial sites. The structures are additionally stabilized by O(w)-H-O and O(w)-H-X hydrogen bonds.

  16. Synthesis, structural, spectral, electrochemical and catalytic properties of VO (IV) complexes containing N, O donors

    NASA Astrophysics Data System (ADS)

    Kanmani Raja, K.; Lekha, L.; Hariharan, R.; Easwaramoorthy, D.; Rajagopal, G.

    2014-10-01

    Complexes of the general formula M (X-DPMP)2 [where, (M = VOIV), DPMP = 2-[(2,6-Diisopropyl-phenylimino)-methyl]-phenol and X = Br, BrCl, Ph] have been synthesized and characterized by IR, electronic, ESR spectral, magnetic and cyclic voltammetry measurements. The newly synthesized Schiff bases act as monobasic bidentate ligand in their complexes. The spectral data indicate that the ligand coordinates through the phenolic oxygen and azomethine nitrogen atoms. The observed parameters, hyperfine splitting constant (A) and Landé splitting energy (g) are found to be in good agreement with the values generally observed for the vanadyl complex with square pyramidal geometry. The cyclic voltammetric redox potentials of VO (IV) complexes suggest the existence of irreversible pairs in acetonitrile. The vanadium complexes were screened for sulfide oxidation studies and VO (C19H21BrON)2 or [VO (Br-DPMP)2] was found to be an efficient catalyst for the oxidation of various sulfides to sulfoxides with PhIO terminal oxidant. Both aryl and alkyl sulfides were selected and converted into sulfoxides in good to excellent yields.

  17. Synthesis, characterization and antibacterial activity of mixed ligand dioxouranium complexes of 8-hydroxyquinoline and some amino acids.

    PubMed

    Patil, Sunil S; Shaikh, Manzoor M

    2012-01-01

    Mixed ligand complexes of dioxouranium(VI) of the type [UO2(Q)(L)-2H2O] have been synthesized using 8-hydroxyquinoline (HQ) as a primary ligand and N- and/or O- donor amino acids (HL) such as L-lysine, L-aspartic acid and L-cysteine as secondary ligands. The metal complexes have been characterized on the basis of elemental analysis, electrical conductance, room temperature magnetic susceptibility measurements, spectral and thermal studies. The electrical conductance studies of the complexes in DMF in 10(-3) M concentration indicate their non-electrolytic nature. Room temperature magnetic susceptibility measurements revealed diamagnetic nature of the complexes. Electronic absorption spectra of the complexes show intra-ligand and charge transfer transitions, respectively. Bonding of the metal ion through N- and O- donor atoms of the ligands is revealed by IR studies and the chemical environment of the protons is also confirmed by NMR studies. The thermal analysis data of the complexes indicate the presence of coordinated water molecules. The agar cup and tube dilution methods have been used to study the antibacterial activity of the complexes against the pathogenic bacteria S. aureus, C. diphtherinae, S. typhi and E. coli. PMID:22876610

  18. Synthesis, structural elucidation, biological, antioxidant and nuclease activities of some 5-Fluorouracil-amino acid mixed ligand complexes

    NASA Astrophysics Data System (ADS)

    Shobana, Sutha; Subramaniam, Perumal; Mitu, Liviu; Dharmaraja, Jeyaprakash; Arvind Narayan, Sundaram

    2015-01-01

    Some biologically active mixed ligand complexes (1-9) have been synthesized from 5-Fluorouracil (5-FU; A) and amino acids (B) such as glycine (gly), L-alanine (ala) and L-valine (val) with Ni(II), Cu(II) and Zn(II) ions. The synthesized mixed ligand complexes (1-9) were characterized by various physico-chemical, spectral, thermal and morphological studies. 5-Fluorouracil and its mixed ligand complexes have been tested for their in vitro biological activities against some pathogenic bacterial and fungal species by the agar well diffusion method. The in vitro antioxidant activities of 5-Fluorouracil and its complexes have also been investigated by using the DPPH assay method. The results demonstrate that Cu(II) mixed ligand complexes (4-6) exhibit potent biological as well as antioxidant activities compared to 5-Fluorouracil and Ni(II) (1-3) and Zn(II) (7-9) mixed ligand complexes. Further, the cleaving activities of CT DNA under aerobic conditions show moderate activity with the synthesized Cu(II) and Ni(II) mixed ligand complexes (1-6) while no activity is seen with Zn(II) complexes (7-9). Binding studies of CT DNA with these complexes show a decrease in intensity of the charge transfer band to the extent of 5-15% along with a minor red shift. The free energy change values (Δ‡G) calculated from intrinsic binding constants indicate that the interaction between mixed ligand complex and DNA is spontaneous.

  19. Cell-free synthesis of isotopically labelled peptide ligands for the functional characterization of G protein-coupled receptors.

    PubMed

    Joedicke, Lisa; Trenker, Raphael; Langer, Julian D; Michel, Hartmut; Preu, Julia

    2016-01-01

    Cell-free systems exploit the transcription and translation machinery of cells from different origins to produce proteins in a defined chemical environment. Due to its open nature, cell-free protein production is a versatile tool to introduce specific labels such as heavy isotopes, non-natural amino acids and tags into the protein while avoiding cell toxicity. In particular, radiolabelled peptides and proteins are valuable tools for the functional characterization of protein-protein interactions and for studying binding kinetics. In this study we evaluated cell-free protein production for the generation of radiolabelled ligands for G protein-coupled receptors (GPCRs). These receptors are seven-transmembrane-domain receptors activated by a plethora of extracellular stimuli including peptide ligands. Many GPCR peptide ligands contain disulphide bonds and are thus inherently difficult to produce in bacterial expression hosts or in Escherichia coli-based cell-free systems. Here, we established an adapted E. coli-based cell-free translation system for the production of disulphide bond-containing GPCR peptide ligands and specifically introduce tritium labels for detection. The bacterial oxidoreductase DsbA is used as a chaperone to favour the formation of disulphide bonds and to enhance the yield of correctly folded proteins and peptides. We demonstrate the correct folding and formation of disulphide bonds and show high-affinity ligand binding of the produced radio peptide ligands to the respective receptors. Thus, our system allows the fast, cost-effective and reliable synthesis of custom GPCR peptide ligands for functional and structural studies. PMID:27047736

  20. Synthesis, structure, and spectral and electrochemical properties of chromium(III) tris-(8-hydroxyquinolinate).

    PubMed

    Freitas, Ana R; Silva, Mónica; Ramos, M Luísa; Justino, Licínia L G; Fonseca, Sofia M; Barsan, Madalina M; Brett, Christopher M A; Silva, M Ramos; Burrows, Hugh D

    2015-07-01

    The kinetically inert chromium(III) tris-(8-hydroxyquinolinate), Crq3, has been synthesized, crystallized from 90% methanol-water, and characterized by MALDI-TOF mass spectrometry, thermogravimetry, FTIR, NMR spectroscopy, and X-ray powder diffraction. It is formed as a methanol solvate, but the solvent can be removed by heating. Large paramagnetic shifts and spectral broadening in (1)H NMR spectra indicate electron delocalization between the metal and the ligand. DFT calculations show it is present as the meridional isomer, with the HOMO largely based on one of the metal 3d orbitals and the LUMO essentially localized on the ligands. Cyclic voltammetry (CV) in acetonitrile solutions shows four oxidation peaks and two, less intense reduction waves on the first scan. The HOMO energy determined from the first oxidation peak is fairly close to that obtained by DFT, in agreement with this being mainly metal based. Although the number of peaks decreases on subsequent CV scans, the complex shows markedly enhanced electrochemical stability compared with aluminium(III) tris-(8-hydroxyquinolinate). Solution UV/visible absorption and solid diffuse reflectance spectra have a weak, long wavelength band, assigned to the metal based d-d transition, in addition to the normal, ligand based bands seen in metal quinolates. The energy of the lowest energy band is identical to the HOMO-LUMO separation obtained by cyclic voltammetry, in agreement with the above description. The compound is only weakly luminescent, in contrast to many other metal quinolates, due to the lowest energy transition being metal rather than ligand based. The potential of this compound as an electron transporting/hole blocking layer in optoelectronic devices is indicated. PMID:26030802

  1. Oxygen spectral line synthesis: 3D non-LTE with CO5BOLD hydrodynamical model atmospheres.

    NASA Astrophysics Data System (ADS)

    Prakapavičius, D.; Steffen, M.; Kučinskas, A.; Ludwig, H.-G.; Freytag, B.; Caffau, E.; Cayrel, R.

    In this work we present first results of our current project aimed at combining the 3D hydrodynamical stellar atmosphere approach with non-LTE (NLTE) spectral line synthesis for a number of key chemical species. We carried out a full 3D-NLTE spectrum synthesis of the oxygen IR 777 nm triplet, using a modified and improved version of our NLTE3D package to calculate departure coefficients for the atomic levels of oxygen in a CO5BOLD 3D hydrodynamical solar model atmosphere. Spectral line synthesis was subsequently performed with the Linfor3D code. In agreement with previous studies, we find that the lines of the oxygen triplet produce deeper cores under NLTE conditions, due to the diminished line source function in the line forming region. This means that the solar oxygen IR 777 nm lines should be stronger in NLTE, leading to negative 3D NLTE-LTE abundance corrections. Qualitatively this result would support previous claims for a relatively low solar oxygen abundance. Finally, we outline several further steps that need to be taken in order to improve the physical realism and numerical accuracy of our current 3D-NLTE calculations.

  2. Synthesis of 3beta-(4-[18F]fluoromethylphenyl)- and 3beta-(2-[18F] fluoromethylphenyl)tropane-2beta-carboxylic acid methyl esters: new ligands for mapping brain dopamine transporter with positron emission tomography.

    PubMed

    Petric, A; Barrio, J R; Namavari, M; Huang, S C; Satyamurthy, N

    1999-07-01

    The synthesis of two new dopamine transporter ligands, 3beta-(4-fluoromethylphenyl)tropane-2beta-carboxylic acid methyl ester and 3beta-(2-fluoromethylphenyl)tropane-2beta-carboxylic acid methyl ester, and their spectral characterization are described. The precursors for these ligands were prepared by TiCl4 catalyzed chloromethylation of 3beta-phenyltropane-2beta-carboxylic acid methyl ester followed by separation of the isomeric product mixture of 2- and 4-chloromethylphenyltropane derivatives. Reaction of the chloromethyl analogs with no-carrier-added [18F]fluoride ion followed by high performance liquid chromatography purification provided the corresponding [18F]fluoromethyltropanes, in good radiochemical yields, useful for imaging the brain dopamine transporter system in vivo with positron emission tomography. PMID:10473191

  3. Synthesis, characterization and biological activity of new mixed ligand complexes of Zn(II) naproxen with nitrogen based ligands.

    PubMed

    Abu Ali, Hijazi; Fares, Hadeel; Darawsheh, Mohanad; Rappocciolo, Emilia; Akkawi, Mutaz; Jaber, Suhair

    2015-01-01

    A series of novel Zn(II) complexes [Zn2(nap)4] (1), [Zn(nap)21,10-phen](2), [Zn(nap)22,9-dmphen] (3), [Zn(nap)2(2-ampy)2] (4), [Zn(nap)2(imid)2] (5), [Zn(nap)2(1,2-dmimid)2] (6) (nap = naproxen, 1,10-phen = 1,10-phenanthroline, 2,9-dmphen = 2,9-dimethyl-1,10-phenanthroline, 2-ampy = 2-aminopyridine, imid = imidazole, 1,2-dmimid = 1,2-dimethyl imidazole) were synthesized and characterized using IR, UV-Vis, (1)H NMR, (13)C{(1)H} NMR spectroscopy. The crystal structure of complex 3 was determined using single-crystal X-ray diffraction. In order to assess the effect of the metal ions on the anti-bacterial activity, complexes 1-6 have been screened in vitro, against (G(+)) bacteria (Staphylococcus aureus and Micrococcus luteus) and (G(-)) bacteria (Klebsiella pneumoniae, Pseudomonas aeruginosa, Proteus mirabilis and Escherichia coli) using the agar well diffusion method. Complex 2 was the only complex that showed antibacterial activity against P. aeruginosa, where the complexation of the parent ligand 1,10-phenathroline enhanced significantly the activity. All the complexes showed different activity against the different bacteria, and were compared with activity of the parent ligands. The complexes were tested also for their anti-malarial activity using two methods: a semi-quantitative micro-assay and a previously self-developed quantitative in-vitro method. Both were used to study the efficiency of these complexes in inhibiting the formation of the Malaria pigment. This is considered an important target of many known anti-malarial drugs such as Chloroquine and Amodaquine. Results showed that the efficiency of complex 3 in preventing the formation of β-hematin was 75%. The efficiency of Amodiaquine as a standard drug was reported to give 92.5. PMID:25462227

  4. Pseudo-peptides as novel antileptospiral agents: Synthesis and spectral characterization

    NASA Astrophysics Data System (ADS)

    Shivamallu, Chandan; Sharanaiah, Umesha; Kollur, Shiva Prasad; Mallesh, Naveen Kumar R.; Hosakere, Revanasiddappa D.; Balamurugan, V.

    2014-01-01

    In this paper, we describe the synthesis of novel class of pseudo-peptides derived by coupling an amino acid with a heterocyclic moiety containing free amine group using suitable coupling agents. The synthesized compounds were characterized using spectral (1H NMR, 13C NMR and MS) techniques. Preliminary pharmacological assays for Leptospirosis were studied by test tube dilution (TDT) and micro dilution technique (MDT). In particular, all the analyses led to the conclusion that the synthesized compound inhibiting the Leptospira a causal organism of Leptospirosis.

  5. Spectral analysis of natural solar ultraviolet B to promote synthesis of vitamin D

    NASA Astrophysics Data System (ADS)

    Hung, Min-Wei; Lin, Yu-Hsuan; Chang, Han-Chao; Huang, Kuo-Cheng

    2016-06-01

    This paper presents a spectral analysis system for the measurement of solar ultraviolet B over long durations. The proposed system provides high resolution at low cost in a highly robust and flexible format. We obtained information pertaining to the absolute irradiance of sunlight in a fixed location with the aim of identifying the best period in which to seek exposure to the sun with regard to maximizing the synthesis of vitamin D while minimizing damage to the skin. This study also provides a means of establishing a database for the development of healthy lamp technology.

  6. Synthesis and binding characteristics of [(3)H]neuromedin N, a NTS2 receptor ligand.

    PubMed

    Tóth, Fanni; Mallareddy, Jayapal Reddy; Tourwé, Dirk; Lipkowski, Andrzej W; Bujalska-Zadrozny, Magdalena; Benyhe, Sándor; Ballet, Steven; Tóth, Géza; Kleczkowska, Patrycja

    2016-06-01

    Neurotensin (NT) and its analog neuromedin N (NN) are formed by the processing of a common precursor in mammalian brain tissue and intestines. The biological effects mediated by NT and NN (e.g. analgesia, hypothermia) result from the interaction with G protein-coupled receptors. The goal of this study consisted of the synthesis and radiolabeling of NN, as well as the determination of the binding characteristics of [(3)H]NN and G protein activation by the cold ligand. In homologous displacement studies a weak affinity was determined for NN, with IC50 values of 454nM in rat brain and 425nM in rat spinal cord membranes. In saturation binding experiments the Kd value proved to be 264.8±30.18nM, while the Bmax value corresponded to 3.8±0.2pmol/mg protein in rat brain membranes. The specific binding of [(3)H]NN was saturable, interacting with a single set of homogenous binding sites. In sodium sensitivity experiments, a very weak inhibitory effect of Na(+) ions was observed on the binding of [(3)H]NN, resulting in an IC50 of 150.6mM. In [(35)S]GTPγS binding experiments the Emax value was 112.3±1.4% in rat brain and 112.9±2.4% in rat spinal cord membranes and EC50 values of 0.7nM and 0.79nM were determined, respectively. NN showed moderate agonist activities in stimulating G proteins. The stimulatory effect of NN could be maximally inhibited via use of the NTS2 receptor antagonist levocabastine, but not by the opioid receptor specific antagonist naloxone, nor by the NTS1 antagonist SR48692. These observations allow us to conclude that [(3)H]NN labels NTS2 receptors in rat brain membranes. PMID:26707235

  7. Ligand-Controlled Divergent Cross-Coupling Involving Organosilicon Compounds for Thioether and Thioester Synthesis.

    PubMed

    Qiao, Zongjun; Jiang, Xuefeng

    2016-04-01

    A divergent cross-coupling for both thioether and thioester construction from organosilicon compounds has been developed. Predominant selectivity for Hiyama-type coupling and C1 insertion reaction was achieved under the guidance of ligands. Thioether was obtained under ligand-free conditions in which disulfide generated from homocoupling could be prevented. Meanwhile, application of bidentate phosphine ligands under carbon monoxide atmosphere (CO balloon) afforded the thioester with little decomposition, which was revealed through interval NMR tracking. PMID:26974172

  8. Synthesis and studies on Cu(II), Co(II), Ni(II) complexes of Knoevenagel β-diketone ligands

    NASA Astrophysics Data System (ADS)

    Sumathi, S.; Tharmaraj, P.; Sheela, C. D.; Anitha, C.

    2012-11-01

    Transition metal complexes of various acetylacetone based ligands of the type ML [where M = Cu(II), Ni(II), Co(II); L = 3-(aryl)-pentane-2,4-dione] have been synthesized. The structural features have been derived from their elemental analysis, magnetic susceptibility, molar conductance, IR, UV-Vis, 1H NMR, Mass and ESR spectral studies. Conductivity measurements reveal that all the complexes are non-electrolytic in nature. Spectroscopic and other analytical data of the complexes suggest octahedral geometry for other metal(II) complexes. The redox behavior of the copper(II) complexes have been studied by cyclic voltammetry. The free ligands and their metal complexes have been screened for their in vitro biological activities against the bacteria Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus as well as the fungus Candida albicans by well diffusion method. The zone of inhibition value indicates that the most of the metal(II) complexes are found to possess increased activities compared to those of the free ligands. All synthesized compounds may serve as potential photoactive materials as indicated from their characteristic fluorescence properties. The second harmonic generation (SHG) efficiency of the ligands (L1-L3) was found to be considerable effect than that of urea and KDP (potassium dihydrogen phosphate).

  9. Design and synthesis of glycoprotein-based multivalent glyco-ligands for influenza hemagglutinin and human galectin-3.

    PubMed

    Wang, Helen; Huang, Wei; Orwenyo, Jared; Banerjee, Aditi; Vasta, Gerardo R; Wang, Lai-Xi

    2013-04-01

    We report a facile synthesis of glycoprotein-based glyco-ligands and their binding with influenza hemagglutinin and human galectin-3. Human serum albumin (HSA) was used as the scaffold and an Asn-linked complex type N-glycan prepared from chicken eggs was used as the glycan building block. It was found that Cu(I)-catalyzed alkyne-azide cycloaddition reaction (click chemistry) between the alkyne-labeled glycan and the azide-tagged HSA led to an efficient formation of the glycoconjugates. The density of glycan ligands on the protein scaffold was readily varied by changing the molar ratios of the two reactants. Binding studies indicated that the sialylated and desialylated multivalent glycoligands could selectively bind to influenza hemagglutinin and human galectin-3, respectively, with high affinity. In the two glycan-lectin interactions, a clear multivalent effect was observed. Moreover, a cell-based assay showed that the synthetic multivalent glyco-ligands could efficiently inhibit the attachment of galectin-3 to human prostate cancer and lung cancer cell lines. This study suggests that the synthetic glycoprotein-based glyco-ligands can be useful for different applications, including blocking the function of galectin-3 in cancer metastasis. PMID:23411399

  10. Design and synthesis of glycoprotein-based multivalent glyco-ligands for influenza hemagglutinin and human galectin-3

    PubMed Central

    Wang, Helen; Huang, Wei; Orwenyo, Jared; Banerjee, Aditi; Vasta, Gerardo R.; Wang, Lai-Xi

    2013-01-01

    We report a facile synthesis of glycoprotein-based glyco-ligands and their binding with influenza hemagglutinin and human galectin-3. Human serum albumin (HSA) was used as the scaffold and an Asn-linked complex type N-glycan prepared from chicken eggs was used as the glycan building block. It was found that Cu(I)-catalyzed alkyne–azide cycloaddition reaction (click chemistry) between the alkyne-labeled glycan and the azide-tagged HSA led to an efficient formation of the glycoconjugates. The density of glycan ligands on the protein scaffold was readily varied by changing the molar ratios of the two reactants. Binding studies indicated that the sialylated and desialylated multivalent glycoligands could selectively bind to influenza hemagglutinin and human galectin-3, respectively, with high affinity. In the two glycan–lectin interactions, a clear multivalent effect was observed. Moreover, a cell-based assay showed that the synthetic multivalent glyco-ligands could efficiently inhibit the attachment of galectin-3 to human prostate cancer and lung cancer cell lines. This study suggests that the synthetic glycoprotein-based glyco-ligands can be useful for different applications, including blocking the function of galectin-3 in cancer metastasis. PMID:23411399

  11. Iron tetraanthracenotetraazaporphyrins: synthesis, structural characterization, ligand binding properties, and unexpected selectivity of a bis-"bowl" tetraazaporphyrin.

    PubMed

    Fitzgerald, Jeffrey P; Lebenson, Joshua R; Wang, Guangbin; Yee, Gordon T; Noll, Bruce C; Sommer, Roger D

    2008-06-01

    The synthesis and characterization, by optical spectroscopy, mass spectrometry, superconducting quantum interference device (SQUID) magnetometry, and single-crystal X-ray diffraction, of six iron complexes of tetraanthracenotetraazaporphyrin (TATAP) are reported. Eight benzo groups, flanking the macrocycle periphery, form a nonpolar "bowl" on each face of the porphyrazine and prevent mu-oxo dimer formation. Fe(TATAP) readily binds THF, a variety of neutral nitrogenous axial ligands, and carbon monoxide. The equilibrium binding constants for the first two are higher than those of analogous porphyrins while those of the latter are smaller. We attribute these differences to the higher pi acidity of the porphyrazine ligand. Fe(TATAP) also shows different relative magnitudes of the successive equilibrium binding constants, K1 and K2, for hindered nitrogenous ligands when compared to those of porphyrin analogues. Surprisingly, Fe(TATAP), in toluene solution, shows no affinity for O2 when exposed to 1 atm partial pressure of O2 at 25 degrees C. These results are explained in terms of an unusually positive iron(III/II) redox potential when coordinated by the TATAP ligand. PMID:18459768

  12. Synthesis, spectra and DNA interactions of certain mononuclear transition metal(II) complexes of macrocyclic tetraaza diacetyl curcumin ligand

    NASA Astrophysics Data System (ADS)

    Rajesh, Jegathalaprathaban; Gubendran, Ammavasi; Rajagopal, Gurusamy; Athappan, Periyakaruppan

    2012-02-01

    A series of mononuclear transition metal(II) complexes of type [M(LL)]2+ (LL = the template condensate of orthophenylene diamine and benzilidene diacetyl curcumin (ben-diacecur) and M = Cu(II) (1) or Co(II) (2) or Ni(II) (3) or Mn(II) (4)), have been isolated and the spectral behaviors are discussed. The ligand and complexes have also been characterized by the analytical and spectral methods like UV-Visible, FT-IR, NMR and EPR. Further, the interaction of the transition metal complexes with Calf thymus (CT) DNA have also been studied by the use of physical methods like UV-Visible, emission and CD spectroscopic techniques. The electrochemical responses of these metal complexes both in presence and absence of DNA have also been demonstrated. All these findings support the hypothesis of DNA interactions of all these metal complexes through the grooves with a higher degree of interaction by complex 1 (Kb = 1.4 × 105) possibly through the interposition of the aromatic rings of the ligand compared to complexes, 2-4. The complex 1 display significant oxidative cleavage of circular plasmid pUC18 DNA in the presence of H2O2 using the singlet oxygen as a reactive species. The spectral and electrochemical response of these complexes designate that the square-planar Cu(II), Ni(II) and Co(II) complexes interact much better than the axially coordinated octahedral Mn(II) complex.

  13. Heteroleptic naphthalo-phthalocyaninates of lutetium: synthesis and spectral and conductivity properties.

    PubMed

    Dubinina, Tatiana V; Kosov, Anton D; Petrusevich, Elizaveta F; Maklakov, Sergey S; Borisova, Nataliya E; Tomilova, Larisa G; Zefirov, Nikolay S

    2015-05-01

    Novel heteroleptic naphthalo-phthalocyaninates of lutetium possessing a symmetrical substituted naphthalocyanine deck were synthesized on the basis of two preformed synthetic blocks: naphthalocyanine ligand and lutetium phthalocyaninates. The compounds obtained were characterized by (1)H NMR and high-resolution MALDI-TOF/TOF mass spectrometry. The correlation between the nature of the substituents and the spectral properties of the target complexes was determined by the introduction of electron-donating (aryl-, aryloxy-) or electron-withdrawing (chloro-) substituents into the phthalocyanine deck. In addition, the nature of peripheral substituents was shown not to affect drastically the phthalocyanine conductivity and activation energy. Conductivity properties depend on thin film morphology which, in turn, relies on intermolecular π-π interactions. PMID:25826576

  14. A series of novel oxovanadium(IV) complexes: Synthesis, spectral characterization and antimicrobial study

    NASA Astrophysics Data System (ADS)

    Sahani, M. K.; Pandey, S. K.; Pandey, O. P.; Sengupta, S. K.

    2014-09-01

    Oxovanadium(IV) complexes have been synthesized by reacting vanadyl sulfate with Schiff bases derived from 4-amino-5-(substitutedphenoxyacetic acid)-1,2,4-triazole-3-thiol and benzil. All these complexes are soluble in DMF and DMSO; low molar conductance values indicate that they are non-electrolytes and characterized by elemental analysis, spectral techniques (UV-Vis, IR, EPR and XRD) and magnetic moment measurements. The EPR spectra indicate that the free electron is in dxy orbital. In vitro antifungal activity of ligands and synthesized compounds was determined against fungi Aspergillus niger, Colletotrichum falcatum and Colletotrichum pallescence and in vitro antibacterial activity was determined by screening the compounds against Gram-negative (Escherichia coli and Salmonella typhi) and Gram-positive (Staphylococcus aureus and Bacillus subtilis) bacterial strains. The antimicrobial activities have shown that the activity increases upon complexation.

  15. Synthesis, spectral characterization and eukaryotic DNA degradation of thiosemicarbazones and their platinum(IV) complexes

    NASA Astrophysics Data System (ADS)

    Al-Hazmi, G. A.; El-Metwally, N. M.; El-Gammal, O. A.; El-Asmy, A. A.

    2008-01-01

    The condensation products of acetophenone (or its derivatives), salicylaldehyde and o-hydroxy- p-methoxybenzophenone with thiosemicarbazide and ethyl- or phenyl-thiosemicarbazide are the investigated thiosemicarbazones. Their reactions with H 2PtCl 6 produced Pt(IV) complexes characterized by elemental, thermal, mass, IR and electronic spectral studies. The coordination modes were found mononegative bidentate in the acetophenone derivatives and binegative tridentate in the salicylaldehyde derivatives. The complexes were analyzed thermogravimetrically and found highly stable. Some ligands and their complexes were screened against Sarcina sp. and E. coli using the cup-diffusion technique. [Pt( oHAT)(OH)Cl] shows higher activity against E. coli than the other compounds. The degradation power of the tested compounds on the calf thymus DNA supports their selectivity against bacteria and not against the human or related eukaryotic organisms.

  16. Synthesis and spectral investigations of Mn(II) complexes of pentadentate bis(thiosemicarbazones)

    NASA Astrophysics Data System (ADS)

    Krishnan, Suja; Laly, K.; Prathapachandra Kurup, M. R.

    2010-02-01

    Five Mn(II) complexes of bis(thiosemicarbazones) which are represented as [Mn(H 2Ac4Ph)Cl 2] ( 1), [Mn(Ac4Ph)H 2O] ( 2), [Mn(H 2Ac4Cy)Cl 2]·H 2O ( 3), [Mn(H 2Ac4Et)Cl 2]·3H 2O ( 4) and [Mn(H 2Ac4Et)(OAc) 2]·3H 2O ( 5) have been synthesized and characterized by elemental analyses, electronic, infrared and EPR spectral techniques. In all the complexes except [Mn(Ac4Ph)H 2O], the ligands act as pentadentate neutral molecules and coordinate to Mn(II) ion through two thione sulfur atoms, two azomethine nitrogens and the pyridine nitrogen, suggesting a heptacoordination. While in compound [Mn(Ac4Ph)H 2O], the dianionic ligand is coordinated to the metal suggesting six coordination in this case. Magnetic studies indicate the high spin state of Mn(II). Conductivity measurements reveal their non-electrolyte nature. EPR studies indicate five g values for [Mn(Ac4Ph)H 2O] showing zero field splitting.

  17. Probing Lipophilic Adamantyl Group as the P1-Ligand for HIV-1 Protease Inhibitors: Design, Synthesis, Protein X-ray Structural Studies, and Biological Evaluation.

    PubMed

    Ghosh, Arun K; Osswald, Heather L; Glauninger, Kristof; Agniswamy, Johnson; Wang, Yuan-Fang; Hayashi, Hironori; Aoki, Manabu; Weber, Irene T; Mitsuya, Hiroaki

    2016-07-28

    A series of potent HIV-1 protease inhibitors with a lipophilic adamantyl P1 ligand have been designed, synthesized, and evaluated. We have developed an enantioselective synthesis of adamantane-derived hydroxyethylamine isosteres utilizing Sharpless asymmetric epoxidation as the key step. Various inhibitors incorporating P1-adamantylmethyl in combination with P2 ligands such as 3-(R)-THF, 3-(S)-THF, bis-THF, and THF-THP were examined. The S1' pocket was also probed with phenyl and phenylmethyl ligands. Inhibitor 15d, with an isobutyl P1' ligand and a bis-THF P2 ligand, proved to be the most potent of the series. The cLogP value of inhibitor 15d is improved compared to inhibitor 2 with a phenylmethyl P1-ligand. X-ray structural studies of 15d, 15h, and 15i with HIV-1 protease complexes revealed molecular insight into the inhibitor-protein interaction. PMID:27389367

  18. Synthesis, physico-chemical properties and complexing abilities of new amphiphilic ligands from D-galacturonic acid.

    PubMed

    Allam, Anas; Behr, Jean-Bernard; Dupont, Laurent; Nardello-Rataj, Véronique; Plantier-Royon, Richard

    2010-04-19

    This paper describes a convenient and efficient synthesis of new complexing surfactants from d-galacturonic acid and n-octanol as renewable raw materials in a two-step sequence. In the first step, simultaneous O-glycosidation-esterification under Fischer conditions was achieved. The anomeric ratio of the products was studied based on the main experimental parameters and the activation mode (thermal or microwave). In the second step, aminolysis of the n-octyl ester was achieved with various functionalized primary amines under standard thermal or microwave activation. The physico-chemical properties of these new amphiphilic ligands were measured and these compounds were found to exhibit interesting surface properties. Complexing abilities of one uronamide ligand functionalized with a pyridine moiety toward Cu(II) ions was investigated in solution by EPR titrations. A solid compound was also synthesized and characterized, its relative structure was deduced from spectroscopic data. PMID:20170906

  19. Designing ancillary ligands for heteroleptic/homoleptic zinc complex formation: synthesis, structures and application in ROP of lactides.

    PubMed

    Jędrzkiewicz, D; Ejfler, J; Gulia, N; John, Ł; Szafert, S

    2015-08-14

    Synthesis and characterization of a series of new amino-phenol/naphthol ligands (L(1,2)-H) have been developed and their respective zinc complexes ( 1 and 2-Zn ) have been synthesized. The molecular structures of L(1)-H and 1, 2-Zn were explored in detail by NMR, single-crystal X-ray studies and DFT calculations, which confirmed the existence of complexes as stabile dimers both in a solution and in the solid state. All complexes mediate the ring-opening polymerization (ROP) of lactide highly efficiently, at room temperature, in a controlled fashion. The influence of the architecture of the ligand on the desired homo/heteroleptic complex formation, as well as the relationship between the initiator design and the catalytic activity have been investigated. PMID:26150026

  20. Wide-Field Imaging Interferometry Spatial-Spectral Image Synthesis Algorithms

    NASA Technical Reports Server (NTRS)

    Lyon, Richard G.; Leisawitz, David T.; Rinehart, Stephen A.; Memarsadeghi, Nargess; Sinukoff, Evan J.

    2012-01-01

    Developed is an algorithmic approach for wide field of view interferometric spatial-spectral image synthesis. The data collected from the interferometer consists of a set of double-Fourier image data cubes, one cube per baseline. These cubes are each three-dimensional consisting of arrays of two-dimensional detector counts versus delay line position. For each baseline a moving delay line allows collection of a large set of interferograms over the 2D wide field detector grid; one sampled interferogram per detector pixel per baseline. This aggregate set of interferograms, is algorithmically processed to construct a single spatial-spectral cube with angular resolution approaching the ratio of the wavelength to longest baseline. The wide field imaging is accomplished by insuring that the range of motion of the delay line encompasses the zero optical path difference fringe for each detector pixel in the desired field-of-view. Each baseline cube is incoherent relative to all other baseline cubes and thus has only phase information relative to itself. This lost phase information is recovered by having point, or otherwise known, sources within the field-of-view. The reference source phase is known and utilized as a constraint to recover the coherent phase relation between the baseline cubes and is key to the image synthesis. Described will be the mathematical formalism, with phase referencing and results will be shown using data collected from NASA/GSFC Wide-Field Imaging Interferometry Testbed (WIIT).

  1. Easily extensible unix software for spectral analysis, display, modification, and synthesis of musical sounds

    NASA Astrophysics Data System (ADS)

    Beauchamp, James W.

    2002-11-01

    Software has been developed which enables users to perform time-varying spectral analysis of individual musical tones or successions of them and to perform further processing of the data. The package, called sndan, is freely available in source code, uses EPS graphics for display, and is written in ansi c for ease of code modification and extension. Two analyzers, a fixed-filter-bank phase vocoder (''pvan'') and a frequency-tracking analyzer (''mqan'') constitute the analysis front end of the package. While pvan's output consists of continuous amplitudes and frequencies of harmonics, mqan produces disjoint ''tracks.'' However, another program extracts a fundamental frequency and separates harmonics from the tracks, resulting in a continuous harmonic output. ''monan'' is a program used to display harmonic data in a variety of formats, perform various spectral modifications, and perform additive resynthesis of the harmonic partials, including possible pitch-shifting and time-scaling. Sounds can also be synthesized according to a musical score using a companion synthesis language, Music 4C. Several other programs in the sndan suite can be used for specialized tasks, such as signal display and editing. Applications of the software include producing specialized sounds for music compositions or psychoacoustic experiments or as a basis for developing new synthesis algorithms.

  2. Synthesis of new chiral monodentate phosphite ligands and their use in catalytic asymmetric hydrogenation.

    PubMed

    Hua, Zihao; Vassar, Victor C; Ojima, Iwao

    2003-10-16

    [reaction: see text] New monodentate phosphite ligands have been developed from axially chiral biphenols, which show excellent enantioselectivity in the Rh(I)-catalyzed hydrogenation of dimethyl itaconate. The new chiral ligand system is suitable to create libraries and possesses fine-tuning capability. PMID:14535721

  3. Biferrocene-Based Diphosphine Ligands: Synthesis and Application of Walphos Analogues in Asymmetric Hydrogenations

    PubMed Central

    2013-01-01

    A total of four biferrocene-based Walphos-type ligands have been synthesized, structurally characterized, and tested in the rhodium-, ruthenium- and iridium-catalyzed hydrogenation of alkenes and ketones. Negishi coupling conditions allowed the biferrocene backbone of these diphosphine ligands to be built up diastereoselectively from the two nonidentical and nonracemic ferrocene fragments (R)-1-(N,N-dimethylamino)ethylferrocene and (SFc)-2-bromoiodoferrocene. The molecular structures of (SFc)-2-bromoiodoferrocene, the coupling product, two ligands, and the two complexes ([PdCl2(L)] and [RuCl(p-cymene)(L)]PF6) were determined by X-ray diffraction. The structural features of complexes and the catalysis results obtained with the newly synthesized biferrocene-based ligands were compared with those of the corresponding Walphos ligands. PMID:23457421

  4. TSPO-ligands prevent oxidative damage and inflammatory response in C6 glioma cells by neurosteroid synthesis.

    PubMed

    Santoro, Anna; Mattace Raso, Giuseppina; Taliani, Sabrina; Da Pozzo, Eleonora; Simorini, Francesca; Costa, Barbara; Martini, Claudia; Laneri, Sonia; Sacchi, Antonia; Cosimelli, Barbara; Calignano, Antonio; Da Settimo, Federico; Meli, Rosaria

    2016-06-10

    Translocator protein 18kDa (TSPO) is predominantly located in the mitochondrial outer membrane, playing an important role in steroidogenesis, inflammation, cell survival and proliferation. Its expression in central nervous system, mainly in glial cells, has been found to be upregulated in neuropathology, and brain injury. In this study, we investigated the anti-oxidative and anti-inflammatory effects of a group of TSPO ligands from the N,N-dialkyl-2-phenylindol-3-ylglyoxylamide class (PIGAs), highlighting the involvement of neurosteroids in their pharmacological effects. To this aim we used a well-known in vitro model of neurosteroidogenesis: the astrocytic C6 glioma cell line, where TSPO expression and localization, as well as cell response to TSPO ligand treatment, have been established. All PIGAs reduced l-buthionine-(S,R)-sulfoximine (BSO)-driven cell cytotoxicity and lipid peroxidation. Moreover, an anti-inflammatory effect was observed due to the reduction of inducible nitric oxide synthase and cyclooxygenase-2 induction in LPS/IFNγ challenged cells. Both effects were blunted by aminoglutethimide (AMG), an inhibitor of pregnenolone synthesis, suggesting neurosteroids' involvement in PIGA protective mechanism. Finally, pregnenolone evaluation in PIGA exposed cells revealed an increase in its synthesis, which was prevented by AMG pre-treatment. These findings indicate that these TSPO ligands reduce oxidative stress and pro-inflammatory enzymes in glial cells through the de novo synthesis of neurosteroids, suggesting that these compounds could be potential new therapeutic tools for the treatment of inflammatory-based neuropathologies with beneficial effects possibly comparable to steroids, but potentially avoiding the negative side effects of long-term therapies with steroid hormones. PMID:27094781

  5. Synthesis, Spectral Characterization, and Biological Evaluation of Transition Metal Complexes of Bidentate N, O Donor Schiff Bases

    PubMed Central

    Sumrra, Sajjad Hussain; Ambreen, Sabahat; Imran, Muhammad; Danish, Muhammad; Rehmani, Fouzia Sultana

    2014-01-01

    New series of three bidentate N, O donor type Schiff bases (L1)–(L3) were prepared by using ethylene-1,2-diamine with 5-methyl furfural, 2-anisaldehyde, and 2-hydroxybenzaldehyde in an equimolar ratio. These ligands were further complexed with Co(II), Cu(II), Ni(II), and Zn(II) metals to produce their new metal complexes having an octahedral geometry. These compounds were characterized on the basis of their physical, spectral, and analytical data. Elemental analysis and spectral data of the uncomplexed ligands and their metal(II) complexes were found to be in good agreement with their structures, indicating high purity of all the compounds. All ligands and their metal complexes were screened for antimicrobial activity. The results of antimicrobial activity indicated that metal complexes have significantly higher activity than corresponding ligands. This higher activity might be due to chelation process which reduces the polarity of metal ion by coordinating with ligands. PMID:25147493

  6. Synthesis of Spectral Data From the Grey Hematite Regions of Mars

    NASA Astrophysics Data System (ADS)

    Calvin, W.; Fallacaro, A.; Baldridge, A.

    2003-12-01

    The martian surface has been mapped by a number of visible and infrared spectral instruments from orbit. Telescopic and historical data sets noted the global albedo distribution of bright and dark units. Work in the near infrared (1 to 5 μ m) identified subtle spectral variations and the appearance of areas with unique signatures. Broad classification of color and near-infrared spectral units include bright ferric material (dust), dark ferrous material (mafic rocks and pyroxene), dark ``crystalline'' ferric material (low albedo but with strong ferric absorptions) and water of hydration in surface materials. The Thermal Emission Spectrometer (TES) on MGS has identified two dominant surface units (mafic/basaltic and basaltic/andesitic-or-glassy-or-weathered). Small outcrops where the spectral signature of bulk grey hematite is exposed at the surface have been identified in Meridiani, Aram Chaos and Valles Marineris. Data from both the Infrared Spectrometers (IRS) on Mariner 6 and 7 and the Imaging Spectrometer for Mars (ISM) show the hematite locations to be more hydrated than other surface regions. Initial comparisons between ISM and the Gamma Ray Spectrometer (GRS) on Odyssey show the increased infrared signature of water in regions also found by GRS to contain more hydrogen. The GRS also shows a broad enhancement of hydrogen over Meridiani and Arabia which covers the hematite outcrop but is much larger in extent. This can be explained if GRS is sensitive both to surface hydration and water at depth in minerals or ice. The preferred interpretation for the bulk hematite units is an aqueous precipitate and synthesis of multiple spectral data sets support that conclusion. A synthesis of the data from these instruments at the hematite locations will be presented. The largest of the sites, in Terra Meridiani, is the landing site for the ``Opportunity'' Mars Exploration Rover which lands Jan 25, 2004. Consideration of constraints imposed by these orbital data sets

  7. Method for generating fractal mountains with controllable macroscopic shapes by spectral synthesis

    NASA Astrophysics Data System (ADS)

    Wang, Humin

    1996-03-01

    Let a 2D random function X(x,y) to denote fBm with exponent 0 < H < 1, then its spectral density Sx(u,v) has relation: Sx(u,v) 1/(u2 + v2)H+1. Such algorithm based on fBm has shown us beautiful pictures of fractal mountains. But the mountains (fractal surfaces) were produced naturally by random process. As a result, the macroscopic shapes and global positions of fractal mounts are not controllable. This paper presents a method that generates fractal mountains with controllable macroscopic shapes and positions using spectral synthesis. First, the discrete data of Y(x,y) on finite grids are inputted, and FFT is employed to produce discrete spectral F(u,v). Second, by InvFFT, low frequency components of F(u,v) together with high frequency components of F(u,v) are transformed to produce Z(x,y)--fractal surface. The macroscopic shapes are controlled by low frequency; meanwhile, the high frequency describes texture of fractal mountains.

  8. The Effects of Magnesium Ions on the Enzymatic Synthesis of Ligand-Bearing Artificial DNA by Template-Independent Polymerase

    PubMed Central

    Takezawa, Yusuke; Kobayashi, Teruki; Shionoya, Mitsuhiko

    2016-01-01

    A metal-mediated base pair, composed of two ligand-bearing nucleotides and a bridging metal ion, is one of the most promising components for developing DNA-based functional molecules. We have recently reported an enzymatic method to synthesize hydroxypyridone (H)-type ligand-bearing artificial DNA strands. Terminal deoxynucleotidyl transferase (TdT), a template-independent DNA polymerase, was found to oligomerize H nucleotides to afford ligand-bearing DNAs, which were subsequently hybridized through copper-mediated base pairing (H–CuII–H). In this study, we investigated the effects of a metal cofactor, MgII ion, on the TdT-catalyzed polymerization of H nucleotides. At a high MgII concentration (10 mM), the reaction was halted after several H nucleotides were appended. In contrast, at lower MgII concentrations, H nucleotides were further appended to the H-tailed product to afford longer ligand-bearing DNA strands. An electrophoresis mobility shift assay revealed that the binding affinity of TdT to the H-tailed DNAs depends on the MgII concentration. In the presence of excess MgII ions, TdT did not bind to the H-tailed strands; thus, further elongation was impeded. This is possibly because the interaction with MgII ions caused folding of the H-tailed strands into unfavorable secondary structures. This finding provides an insight into the enzymatic synthesis of longer ligand-bearing DNA strands. PMID:27338351

  9. EPR, magnetic and spectral studies of copper(II) and nickel(II) complexes of schiff base macrocyclic ligand derived from thiosemicarbazide and glyoxal

    NASA Astrophysics Data System (ADS)

    Chandra, Sulekh; Sangeetika, X.

    2004-01-01

    A new macrocylic Schiff base 1,2,5,6,8,11-hexaazacyclododeca-7,12-dithione-2,4,8,10-tetraene(H 2L 4) containing thiosemicarbazone moiety is readily prepared and characterized for the first time with fairly good yield. Macrocylic ligand (H 2L 4) is prepared from the mesocyle 6-ethoxy-4-thio-2,3,5-triazine(H 2L 3) in ethanol with copper chloride acting as template using high dilution technique. The complexes of macrocylic ligand with a general composition M(H 2L 4)X 2 [where M=Cu(II) or Ni(II); H 2L 4=1,2,5,6,8,11-hexaazacyclo dodeca-7,12-dithione-2,4,8,10-tetraene; X= Cl -, NO 3-, 1/ 2SO 42-] and ML 4 (where metal salt used to synthesize complex is copper acetate and nickel thiocyanate) have been synthesized. The complexes were characterized on the basis of elemental analysis, molar conductance, magnetic susceptibility, IR, electronic, 1H NMR, mass and EPR spectral studies. The complexes from H 2L 4 show different stoichiometry ratio and with a variable grade of deprotonation in the ligand, depending upon the salt used and working conditions.

  10. Remarkably diastereoselective synthesis of a chiral biphenyl diphosphine ligand and its application in asymmetric hydrogenation

    PubMed Central

    Qiu, Liqin; Wu, Jing; Chan, Shusun; Au-Yeung, Terry T.-L.; Ji, Jian-Xin; Guo, Rongwei; Pai, Cheng-Chao; Zhou, Zhongyuan; Li, Xingshu; Fan, Qing-Hua; Chan, Albert S. C.

    2004-01-01

    Essentially complete atropdiastereoselectivity was realized in the preparation of biaryl diphosphine dioxide by asymmetric intramolecular Ullmann coupling and oxidative coupling with central-to-axial chirality transfer. A bridged C2-symmetric biphenyl phosphine ligand possessing additional chiral centers on the linking unit of the biphenyl groups was synthesized. No resolution step was required for the preparation of the enantiomerically pure chiral ligand. These findings offer a general and practical tool for the development of previously uninvestigated atropdiastereomeric biaryl phosphine ligands. The diphosphine ligand was found to be highly effective in the asymmetric hydrogenation of α- and β-ketoesters, 2-(6′-methoxy-2′-naphthyl)propenoic acid, β-(acylamino)acrylates, and enol acetates. PMID:15067137

  11. Design and synthesis of carborane-containing estrogen receptor-beta (ERβ)-selective ligands.

    PubMed

    Ohta, Kiminori; Ogawa, Takumi; Oda, Akifumi; Kaise, Asako; Endo, Yasuyuki

    2015-10-01

    Candidates for highly selective estrogen receptor-beta (ERβ) ligands (6a-c, 7a-c, 8a and 8b) were designed and synthesized based on carborane-containing ER ligands 1 and 2 as lead compounds. Among them, p-carboranylcyclohexanol derivatives 8a and 8b exhibited high ERβ selectivity in competitive binding assay: for example, 8a showed 56-fold selectivity for ERβ over ERα. Docking studies of 8a and 8b with the ERα and ERβ ligand-binding domains (LBDs) suggested that the p-carborane cage of the ligands is located close to key amino acid residues that influence ER-subtype selectivity, that is, Leu384 in the ERα LBD and Met336 in the ERβ LBD. The p-carborane cage in 8a and 8b appears to play a crucial role in the increased ERβ selectivity. PMID:26298498

  12. Design and synthesis of dual 5-HT1A and 5-HT7 receptor ligands.

    PubMed

    Ofori, Edward; Zhu, Xue Y; Etukala, Jagan R; Peprah, Kwakye; Jordan, Kamanski R; Adkins, Adia A; Bricker, Barbara A; Kang, Hye J; Huang, Xi-Ping; Roth, Bryan L; Ablordeppey, Seth Y

    2016-08-15

    5-HT1A and 5-HT7 receptors have been at the center of discussions recently due in part to their major role in the etiology of major central nervous system diseases such as depression, sleep disorders, and schizophrenia. As part of our search to identify dual targeting ligands for these receptors, we have carried out a systematic modification of a selective 5HT7 receptor ligand culminating in the identification of several dual 5-HT1A and 5-HT7 receptor ligands. Compound 16, a butyrophenone derivative of tetrahydroisoquinoline (THIQ), was identified as the most potent agent with low nanomolar binding affinities to both receptors. Interestingly, compound 16 also displayed moderate affinity to other clinically relevant dopamine receptors. Thus, it is anticipated that compound 16 may serve as a lead for further exploitation in our quest to identify new ligands with the potential to treat diseases of CNS origin. PMID:27312422

  13. Zwitterionic phosphonium ligands: synthesis, characterization and application in telomerization of 1,3-butadiene.

    PubMed

    Pews-Davtyan, A; Jackstell, R; Spannenberg, A; Beller, M

    2016-06-18

    Novel zwitterionic phosphonium alkylsulfonate ligands are chemoselectively synthesized from N-heterocyclic phosphines and cyclic sulfones in one step in good to excellent yields. Their in situ generated palladium complexes showed high productivity in the industrial telomerization of 1,3-butadiene with methanol. Optimal results are obtained in the presence of cyclohexyl-substituted ligands under mild conditions and at metal loadings as low as 0.001 mol%. PMID:27215145

  14. Synthesis and Structure of a Ternary Copper(II) Complex with Mixed Ligands of Diethylenetriamine and Picrate: DNA/Protein-Binding Property and In Vitro Anticancer Activity Studies.

    PubMed

    Shi, Ya-Ning; Zheng, Kang; Zhu, Ling; Li, Yan-Tuan; Wu, Zhi-Yong; Yan, Cui-Wei

    2015-05-01

    Based on the importance of the design and synthesis of transition metal complexes with noncovalent DNA/protein-binding abilities in the field of metallo pharmaceuticals, a new mononuclear ternary copper(II) complex with mixed ligands of diethylenetriamine (dien) and picrate anion (pic), identified as [Cu(dien)(pic)](pic), was synthesized and characterized by elemental analysis, molar conductivity measurement, infrared spectrum, electronic spectral studies, and single-crystal X-ray diffractometry. The structure analysis reveals that the copper(II) complex crystallizes in the monoclinic space group P21 /c, and the copper(II) ion has a distorted square pyramidal coordination geometry. A two-dimensional supramolecular structure is formed through hydrogen bonds. The DNA/bovine serum albumin (BSA)-binding properties of the complex are explored, indicating that the complex can interact with herring sperm DNA via intercalation mode and bind to BSA responsible for quenching of tryptophan fluorescence by static quenching mechanism. The in vitro anticancer activity shows that the copper(II) complex is active against the selected tumor cell lines. PMID:25652782

  15. Synthesis and structures of four homochiral metal camphorates with auxiliary bipyridine ligands

    NASA Astrophysics Data System (ADS)

    Yang, E.; Lian, Ting-Ting; Lin, Shen; Chen, Shu-Mei

    2011-12-01

    Four homochiral metal camphorates with auxiliary bipyridine ligands are hydrothermally synthesized and structurally characterized. The structure of compound [Cd( D-Hcam) 2(bpa)(H 2O)] n ( 1; D-H 2cam = D-(+)-camphoric acid, bpa = 1,2-bis(4-pyridyl)-ethane) presents a rare case where the D-Hcam is not a bridging ligand, but a dangling unit attached to the infinite [Cd(bpa)] chain. Compounds [M 2( D-cam) 2(4,4'-bipy)(H 2O) 4] n (M = Co, 2; M = Cd, 3; 4,4'-bipy = 4,4'-bipyridine) are isostructural and have homochiral [M( D-cam)] n chains linked by the 4,4'-bipy ligands into a honeycomb-like 6 3 layer. Compound [Zn 2( D-cam) 2(PPE) 2] n ( 4, PPE = 1-(4-pyridyl)-2-(2-pyridyl)-ethylene) consists of the grid-like 4 4 layers with the dinuclear Zn 2(COO) 4 units and D-cam ligands, where the PPE ligands are only monodentately coordinated to the dinuclear units and act as the separators between two homochiral layers. The results demonstrate the rich coordination chemistry of the enantiopure D-camphorate ligand and the structural diversity of metal-camphorate compounds.

  16. Synthesis, characterization, and stability of iron (III) complex ions possessing phenanthroline-based ligands

    PubMed Central

    Rios, Andrew; Frias, Elma; Eichler, Jack F.

    2014-01-01

    It has previously been demonstrated that phenanthroline-based ligands used to make gold metallotherapuetics have the ability to exhibit cytotoxicity when not coordinated to the metal center. In an effort to help assess the mechanism by which these ligands may cause tumor cell death, iron binding and removal experiments have been considered. The close linkage between cell proliferation and intracellular iron concentrations suggest that iron deprivation strategies may be a mechanism involved in inhibiting tumor cell growth. With the creation of iron (III) phen complexes, the iron binding abilities of three polypyridal ligands [1,10-phenanthroline (phen), 2,9-dimethyl-1, 10-phenanthroline (methylphen), and 2,9-di-sec-butyl-1, 10-phenanthroline (sec-butylphen)] can be tested via a competition reaction with a known iron chelator. Therefore, iron (III) complexes possessing all three ligands were synthesized. Initial mass spectrometric and infrared absorption data indicate that iron (III) tetrachloride complex ions with protonated phen ligands (RphenH+) were formed: [phenH][FeCl4], [methylphenH][FeCl4], [sec-butylphenH][FeCl4]. UV-Vis spectroscopy was used to monitor the stability of the complex ions, and it was found that the sec-butylpheniron complex was more stable than the phen and methylphen analogues. This was based on the observation that free ligand was observed immediately upon the addition of EDTA to the [phenH][FeCl4] and [methylphenH] [FeCl4] complex ions. PMID:25379358

  17. Bivalent Approach for Homodimeric Estradiol Based Ligand: Synthesis and Evaluation for Targeted Theranosis of ER(+) Breast Carcinomas.

    PubMed

    Chauhan, Kanchan; Arun, Ashutosh; Singh, Saurabh; Manohar, Murli; Chuttani, Krishna; Konwar, Rituraj; Dwivedi, Anila; Soni, Ravi; Singh, Ajai Kumar; Mishra, Anil K; Datta, Anupama

    2016-04-20

    The synthesis of estradiol based bivalent ligand [(EST)2DT] is reported and its potential for targeted imaging and therapy of ER(+) tumors has been evaluated. For the purpose, ethinylestradiol was functionalized with an azidoethylamine moiety via click chemistry. The resultant derivative was reacted in a bivalent mode with DTPA-dianhydride to form the multicoordinate chelating agent, (EST)2DT which displayed capability to bind (99m)Tc. The radiolabeled complex, (99m)Tc-(EST)2DT was obtained in >99% radiochemical purity and 20-48 GBq/μmol of specific activity. RBA assay revealed ∼15% binding with estrogen receptor. Evaluation of ligand on ER(+)-cell line (MCF-7) suggested enhanced and ER-mediated uptake. In vivo assays displayed early tracer accumulation in MCF-7 xenografts with tumor to muscle ratio ∼6 in 2 h and negligible uptakes in nontargeted organs. MTT assay performed on ER(+) and ER(-) cell lines displayed selective inhibition of ER(+) cancer cell growth with IC50 = 14.3 μM which was comparable to tamoxifen. The anticancer activity of the ligand is possibly due to the increase in ERβ and suppression of ERα protein levels in gene transcription. The studies reveal the potential of (EST)2DT as diagnostic imaging agent with the additional benefits in therapy. PMID:26999669

  18. Quaternary Cu2ZnSnS4 quantum dot-sensitized solar cells: Synthesis, passivation and ligand exchange

    NASA Astrophysics Data System (ADS)

    Bai, Bing; Kou, Dongxing; Zhou, Wenhui; Zhou, Zhengji; Tian, Qingwen; Meng, Yuena; Wu, Sixin

    2016-06-01

    The quaternary Cu2ZnSnS4 (CZTS) QDs had been successfully introduced into quantum dot-sensitized solar cells (QDSC) via hydrolysis approach in our previous work [Green Chem. 2015, vol. 17, p. 4377], but the obtained cell efficiency was still limited by low open-circuit voltage and fill factor. Herein, we use 1-dodecanethiol (DDT) as capping ligand for fairly small-sized CZTS QDs synthesis to improve their intrinsic properties. Since this strong bonded capping ligand can not be replaced by 3-mercaptopropionic acid (MPA) directly, the nature cation (Cu, Zn or Sn)-DDT units of QDs are first exchanged by the preconjugated Cd-oleate via successive ionic layer adsorption and reaction (SILAR) procedure accompanied with the formation of a core/shell structure. The weak bonded oleic acid (OA) can be finally replaced by MPA and the constructed water soluble CZTS/CdSe QDSC achieves an impressive conversion efficiency of 4.70%. The electron transport and recombination dynamic processes are confirmed by intensity-modulated photocurrent spectroscopy (IMPS)/intensity-modulated photovoltage spectroscopy (IMVS) measurements. It is found that the removal of long alkyl chain is conducive to improve the electron transport process and the type-II core/shell structure is beneficial to accelerate electron transport and retard charge recombination. This effective ligand removal strategy is proved to be more convenient for the applying of quaternary QDs in QDSC and would boost a more powerful efficiency in the future work.

  19. Synthesis and characterization of luminescent square-planar platinum(II) complexes containing dithiolate or dithiocarbamate ligands

    SciTech Connect

    Bevilacqua, J.M.; Eisenberg, R.

    1994-06-22

    The synthesis, characterization, and emission properties of a series of Pt(L{sub 2})(S-S) complexes are reported. The (L{sub 2}) ligands include 4,7-diphenyl-1,10-phenanthroline (Ph{sub 2}phen), 4,4{prime}-dimethyl-2,2{prime}-bipyridine (Me{sub 2}bpy), 1,5-cyclo-octadiene (COD), trimethyl phosphite (P(OMe){sub 3}), and the {alpha}-C-deprotonated form of 2-phenylpyridine (2-phpy). The (S-S) ligands include 1-(tert-butoxycarbonyl)-1-cyanoethylene-2,2-dithiolate (tbcda), 1-(diethoxyphosphinyl)-1-cyanoethylene-2,2-dithiolate (cpdt), cis-1,2-dicarbomethoxyethylene-1,2-dithiolate (met), and N,N-diethyldithio-carbamate (Et{sub 2}dtc). The complexes are readily synthesized by the addition of the dithiolate or thiolate ligand to Pt(L{sub 2})Cl{sub 2} except for Pt(P(OMe){sub 3}){sub 2}(met), which is prepared by the addition of 2 equiv of trimethyl phosphite to Pt(COD)(met).

  20. Synthesis and Structure Determination of a New Au20 Nanocluster Protected by Tripodal Tetraphosphine Ligands

    SciTech Connect

    Chen, Jing; Zhang, Qianfan; Williard, Paul G.; Wang, Lai-Sheng

    2014-03-31

    We report the synthesis and structure determination of a new Au20 nanocluster coordinated by four tripodal tetraphosphine (PP3) ligands {PP3 = tris[2-(diphenylphosphino)ethyl]phosphine}. Single-crystal Xray crystallography and electrospray ionization mass spectrometry show that the cluster assembly can be formulated as [Au20(PP3)4]Cl4. The Au20 cluster consists of an icosahedral Au13 core and a seven-Au-atom partial outer shell arranged in a local C3 symmetry. One PP3 ligand coordinates to four Au atoms in the outer shell, while the other three PP3 ligands coordinate to one Au atom from the outer shell and three Au atoms from the surface of the Au13 core, giving rise to an overall chiral 16-electron Au cluster core with C3 symmetry.

  1. DFT modeling of Spectral and Redox Properties of Di-and Tetranuclear Ruthenium Transition Metal Complexes with Bridging Ligands

    SciTech Connect

    Zalis, S.; Winter, R. S.; Linseis, M.; Kaim, A.; Sarkar, B.; Kratochvilova, I.

    2009-08-13

    The electronic structures of di-and tetranuclear transition metal complexes with bridging ligands (tetracyanoethene, tetracyano-p-quinodimethane, divinylphenylene and tetrakis(4-styryl)ethene) were calculated by density functional (DFT) method. DFT method was used for calculations of IR frequencies in different oxidation states and EPR parameters of radical ions. The observed electronic transitions of closed shell systems were assigned by TD DFT. The different aspects of bridge mediated metal-metal interaction are discussed.

  2. Bis-cyclometalated iridium(III) complexes bearing ancillary guanidinate ligands. Synthesis, structure, and highly efficient electroluminescence.

    PubMed

    Rai, Virendra Kumar; Nishiura, Masayoshi; Takimoto, Masanori; Zhao, Shanshan; Liu, Yu; Hou, Zhaomin

    2012-01-16

    We report the synthesis, structure, and photophysical and electroluminescent (EL) properties of a series of heteroleptic bis(pyridylphenyl)iridium(III) complexes with various ancillary guanidinate ligands. The reaction of the bis(pyridylphenyl)iridium(III) chloride [(ppy)(2)Ir(μ-Cl)](2) with the lithium salt of various guanidine ligands Li{(N(i)Pr)(2)C(NR(1)R(2))} at 80 °C gave in 60-80% yield the corresponding heteroleptic bis(pyridylphenyl)/guanidinate iridium(III) complexes having a general formula of [(ppy)(2)Ir{(N(i)Pr)(2)C(NR(1)R(2))}], where NR(1)R(2) = NPh(2) (1), N(C(6)H(4)(t)Bu-4)(2) (2), carbazolyl (3), 3,6-bis(tert-butyl)carbazolyl (4), N(C(6)H(4))(2)S (5), N(C(6)H(4))(2)O (6), indolyl (7), NEt(2) (8), N(i)Pr(2) (9), N(i)Bu(2) (10), and N(SiMe(3))(2) (11). These heteroleptic cyclometalated (C^N) iridium(III) complexes showed intense absorption bands in the UV region assignable to π-π* transitions and weaker metal-to-ligand charge-transfer transitions extending to the visible region. These complexes also showed intense emissions at room temperature. Their photoluminescence spectra were influenced to some extent by the ancillary guanidinate ligands, giving λ(max) values in the range of 528-560 nm with quantum yields (Φ) of 0.16-0.37 and lifetimes of 0.61-1.43 μs. Organic light-emitting diodes were fabricated by the use of these complexes as dopants in various concentrations (5-100%) in a N,N'-dicarbazolylbiphenyl host. High current efficiency (η(c); up to 137.4 cd/A) and power efficiency (η(p); up to 45.7 lm/W) were observed under appropriate conditions. Their high EL efficiency may result from efficient trapping and radiative relaxation of the excitons formed in the EL process. Because of the steric hindrance of the guanidinate ligands, no significant intermolecular interaction was observed in these complexes, thus leading to the reduction of self-quenching and triplet-triplet annihilation at high currents. The EL emission color could be changed

  3. Coinage metal complexes with bridging hybrid phosphine-NHC ligands: synthesis of di- and tetra-nuclear complexes.

    PubMed

    Simler, Thomas; Braunstein, Pierre; Danopoulos, Andreas A

    2016-03-28

    A series of P-NHC-type hybrid ligands containing both PR2 and N-heterocyclic carbene (NHC) donors on meta-bis-substituted phenylene backbones, L(Cy), L(tBu) and L(Ph) (R = Cy, tBu, Ph, respectively), was accessed through a modular synthesis from a common precursor, and their coordination chemistry with coinage metals was explored and compared. Metallation of L(Ph)·n(HBr) (n = 1, 2) with Ag2O gave the pseudo-cubane [Ag4Br4(L(Ph))2], isostructural to [Ag4Br4(L(R))2] (R = Cy, tBu) (T. Simler, P. Braunstein and A. A. Danopoulos, Angew. Chem., Int. Ed., 2015, 54, 13691), whereas metallation of ·HBF4 (R = Ph, tBu) led to the dinuclear complexes [Ag2(L(R))2](BF4)2 which, in the solid state, feature heteroleptic Ag centres and a 'head-to-tail' (HT) arrangement of the bridging ligands. In solution, interconversion with the homoleptic 'head-to-head' (HH) isomers is facilitated by ligand fluxionality. 'Head-to-tail' [Cu2Br2(L(R))2] (R = Cy, tBu) dinuclear complexes were obtained from L(R)·HBr and [Cu5(Mes)5], Mes = 2,4,6-trimethylphenyl, which also feature bridging ligands and heteroleptic Cu centres. Although the various ligands L(R)l ed to structurally analogous complexes for R = Cy, tBu and Ph, the rates of dynamic processes occurring in solution are dependent on R, with faster rates for R = Ph. Transmetallation of both NHC and P donor groups from [Ag4Br4(L(tBu))2] to AuI by reaction with [AuCl(THT)] (THT = tetrahydrothiophene) led to L(tBu) transfer and to the dinuclear complex [Au2Cl2L(tBu)] with one L(tBu) ligand bridging the two Au centres. Except for the silver pseudo-cubanes, all other complexes do not exhibit metallophilic interactions. PMID:26886084

  4. Rhodium Complex with Ethylene Ligands Supported on Highly Dehydroxylated MgO: Synthesis, Characterization, and Reactivity

    SciTech Connect

    Bhirud,V.; Ehresmann, J.; Kletnieks, P.; Haw, J.; Gates, B.

    2006-01-01

    Mononuclear rhodium complexes with reactive olefin ligands, supported on MgO powder, were synthesized by chemisorption of Rh(C2H4)2(C5H7O2) and characterized by infrared (IR), {sup 13}C MAS NMR, and extended X-ray absorption fine structure (EXAFS) spectroscopies. IR spectra show that the precursor adsorbed on MgO with dissociation of acetylacetonate ligand from rhodium, with the ethylene ligands remaining bound to the rhodium, as confirmed by the NMR spectra. EXAFS spectra give no evidence of Rh-Rh contributions, indicating that site-isolated mononuclear rhodium species formed on the support. The EXAFS data also show that the mononuclear complex was bonded to the support by two Rh-O bonds, at a distance of 2.18 Angstroms, which is typical of group 8 metals bonded to oxide supports. This is the first simple and nearly uniform supported mononuclear rhodium-olefin complex, and it appears to be a close analogue of molecular catalysts for olefin hydrogenation in solution. Correspondingly, the ethylene ligands bonded to rhodium in the supported complex were observed to react with H{sub 2} to form ethane, and the supported complex was catalytically active for the ethylene hydrogenation at 298 K. The ethylene ligands also underwent facile exchange with C{sub 2}D{sub 4}, and exposure of the sample to carbon monoxide led to the formation of rhodium gem dicarbonyls.

  5. Synthesis and reactions of U(III) complexes with tripodal nitrogen and oxygen donor ligands

    NASA Astrophysics Data System (ADS)

    McDonald, Robert; Sun, Yimin; Takats, Josef; Day, Victor W.; Eberspracher, Todd A.

    1994-10-01

    Reaction of UI3(THF)4 (where THF is tetrahydrofuran) with sodium or potassium hydrotris(3,5-dimethylpyrazolyl)borate ligand ((HBpz 3*)(-) in 1:1 and 1:2 ratios gives the corresponding U(HBpz 3*)I2(THF)2(1) and U(HBpz 3*)2I(2) complexes in excellent yields. Iodide abstraction from (2) with TlBPh4 results in the formation of the cationic complex (U(HBpz 3*)2(THF)) BPh4(3). The solid state structures of 1, 2 and 3 have been determined. Similar reactions with the anionic tripodal oxygen donor ligand ((eta (sub 5) - (5H5) Co(P(O)(OC2H5)2)3)(-) (L(sub OEt)) proceeded via oxidation of U(3+) to U(4+) and fragmentation of the ligand. The structures of some key compounds were established by X-ray crystallography. U(HBpz 3*)I2(THF)2 readily reacts with two equivalents of KH2Bpz (pz equivalent to pyrazolyl) to give U(HBpz3*)(H2Bpz2)2, but attempted substitution with other ligands led to mixtures or, in one case, displacement of the (HBpz 3*)(-) ligand.

  6. Synthesis of ligands containing N-oxide donor atoms and their assembly into metallosupramolecular structures.

    PubMed

    Bullock, Samantha J; Harding, Lindsay P; Moore, Michelle P; Mills, Andrew; Piela, Sean A F; Rice, Craig R; Towns-Andrews, Liz; Whitehead, Martina

    2013-04-28

    A series of ligands that contain both N-donor and N-oxide donor atoms have been synthesised and ligands L5, L6, L7 and L8 contain, 4, 6, 5, and 6 donor atoms respectively. The smallest ligand L5 forms a mononuclear complex with Cu2+ ([Cu(L5)(ClO4)2(MeCN)]) whereas L6 and L7 form dinuclear double helicates with Ni2+ and Cu2+ respectively ([Ni2(L6)2]4+ and [Cu2(L7)2]4+). L8 forms a tetranuclear cyclic helicate upon reaction with Co2+ ([Co4(L8)4]8+) and in all cases the complexes are characterised by single-crystal X-ray diffraction and ESI-MS. The N-oxide units imparts flexibility in the ligand strand and where the unoxidised ligand strand forms a cyclic helicate, the incorporation of an N-oxide unit allows the formation of the dinuclear double helicate. PMID:23462743

  7. Synthesis of Janus-like gold nanoparticles with hydrophilic/hydrophobic faces by surface ligand exchange and their self-assemblies in water.

    PubMed

    Iida, Ryo; Kawamura, Hitoshi; Niikura, Kenichi; Kimura, Takashi; Sekiguchi, Shota; Joti, Yasumasa; Bessho, Yoshitaka; Mitomo, Hideyuki; Nishino, Yoshinori; Ijiro, Kuniharu

    2015-04-14

    This study aims at the synthesis of Janus gold nanoparticles (Janus GNPs) with hydrophilic/hydrophobic faces by a simple ligand exchange reaction in an homogeneous system and at the elucidation of the self-assembled structures of the Janus GNPs in water. As hydrophilic surface ligands, we synthesized hexaethylene glycol (E6)-terminated thiolate ligands with C3, C7, or C11 alkyl chains, referred to as E6C3, E6C7, and E6C11, respectively. As a hydrophobic ligand, a butyl-headed thiolate ligand C4-E6C11, in which a C4 alkyl was introduced on the E6C11 terminus, was synthesized. The degree of segregation between the two ligands on the GNPs (5 nm in diameter) was examined by matrix-assisted laser desorption/ionization time-of fright mass spectrometry (MALDI-TOF MS) analysis. We found that the choice of immobilization methods, one-step or two-step addition of the two ligands to the GNP solution, crucially affects the degree of segregation. The two-step addition of a hydrophilic ligand (E6C3) followed by a hydrophobic ligand (C4-E6C11) produced a large degree of segregation on the GNPs, providing Janus-like GNPs. When dispersed in water, these Janus-like GNPs formed assemblies of ∼160 nm in diameter, whereas Domain GNPs, in which the two ligands formed partial domains on the surface, were precipitated even when the molar ratio of the hydrophilic ligand and the hydrophobic ligand on the surface of the NPs was almost 1:1. The assembled structure of the Janus-like GNPs in water was directly observed by pulsed coherent X-ray solution scattering using an X-ray free-electron laser, revealing irregular spherical structures with uneven surfaces. PMID:25796963

  8. Synthesis, Structure, Electrochemistry, and Spectral Characterization of Bis-Isatin Thiocarbohydrazone Metal Complexes and Their Antitumor Activity Against Ehrlich Ascites Carcinoma in Swiss Albino Mice

    PubMed Central

    Sathisha, M. P.; Revankar, V. K.; Pai, K. S. R.

    2008-01-01

    The synthesis, structure, electrochemistry, and biological studies of Co(II), Ni(II), Cu(II), and Zn(II) complexes of thiocarbohydrazone ligand are described. The ligand is synthesized starting from thiocarbohydrazide and isatin. It is evident from the IR data that in all the complexes, only one part of the ligand is coordinated to the metal ion resulting mononuclear complexes. The ligand coordinates essentially through the carbonyl oxygen of the isatin fragment, the nitrogen atom of the azomethine group, and sulfur atom after deprotonation to give five membered rings. H1 NMR spectrum of the ligand shows only one set of signals for the aromatic protons, while the NH of isatin and NH of hydrazone give rise to two different singlets in the 11–14 ppm range. The formulations, [Cu(L)Cl]·2H2O, [Cu(L)(CH3COO)]·2H2O, [Ni(L)Cl], [Ni(L)(CH3COO)], [Co(L2)], and [Zn(L2)]·2H2O are in accordance with elemental analyses, physical, and spectroscopic measurements. The complexes are soluble in organic solvents. Molar conductance values in DMF indicate the nonelectrolytic nature of the complexes. Copper complex displays quasireversible cyclic voltametric responses with Ep near −0.659 v and 0.504 v Vs Ag/AgCl at the scan rate of 0.1 V/s. Copper(II) complexes show a single line EPR signals. For the observed magnetic moment and electronic spectral data possible explanation has been discussed. From all the available data, the probable structures for the complexes have been proposed. The compounds synthesized in present study have shown promising cytotoxic activity when screened using the in vitro method and at the same time were shown to have good activity when tested using the Ehrlich ascites carcinoma (EAC) model. The antimicrobial screening showed that the cobalt complex possesses enhanced antimicrobial activity towards fungi. PMID:18320020

  9. The synthesis and characterization of new iron coordination complexes utilizing an asymmetric coordinating chelate ligand

    SciTech Connect

    Watkins, B.E.; Satcher, J.H.

    1995-07-01

    A binuclear, unsymmetric coordinating ligand that is an effective metal chelator has been designed and synthesized. The new ligand has been shown to react readily with iron(II)/(III) forming a variety of coordination complexes. The binuclear complexes are of significant interest since they represent proof-of-principle for the development of coordinatively asymmetric, binuclear metal chelate compounds. Although this structural type of chelator now appears to be common in biological systems, it has not been previously described for inorganic coordination chemistry. The isolation of oxidation products will be helpful in establishing reaction mechanism(s) of these complexes with molecular oxygen. It is expected that this ligand and derivatives of it will play an important role in the development of bioinorganic complexes that aim to mimic enzyme active sites that function by substrate interaction at only one metal site of a multimetal active site.

  10. Synthesis, characterization and luminescent properties of lanthanide complexes with a novel multipodal ligand

    NASA Astrophysics Data System (ADS)

    Yan, Zhen-Zhong; Hou, Na; Wang, Cong-Min

    2015-02-01

    Solid complexes of lanthanide nitrates with an novel multipodal ligand, 1,2,4,5-tetramethyl-3,6-bis{N,N-bis[((2‧-furfurylaminoformyl)phenoxyl)ethyl]-aminomethyl}-benzene (L) have been synthesized and characterized by elemental analysis, infrared spectra and molar conductivity measurements. At the same time, the luminescent properties of the Sm(III), Eu(III), Tb(III) and Dy(III) nitrate complexes in solid state were investigated. Under the excitation of UV light, these complexes exhibited characteristic emission of central metal ions. The lowest triplet state energy level of the ligand indicates that the triplet state energy level (T1) of the ligand matches better the resonance level of Tb(III) than other lanthanide ions.

  11. Synthesis, characterization and luminescent properties of lanthanide complexes with a novel multipodal ligand.

    PubMed

    Yan, Zhen-Zhong; Hou, Na; Wang, Cong-Min

    2015-02-25

    Solid complexes of lanthanide nitrates with an novel multipodal ligand, 1,2,4,5-tetramethyl-3,6-bis{N,N-bis[((2'-furfurylaminoformyl)phenoxyl)ethyl]-aminomethyl}-benzene (L) have been synthesized and characterized by elemental analysis, infrared spectra and molar conductivity measurements. At the same time, the luminescent properties of the Sm(III), Eu(III), Tb(III) and Dy(III) nitrate complexes in solid state were investigated. Under the excitation of UV light, these complexes exhibited characteristic emission of central metal ions. The lowest triplet state energy level of the ligand indicates that the triplet state energy level (T1) of the ligand matches better the resonance level of Tb(III) than other lanthanide ions. PMID:25305620

  12. Synthesis of a hybrid m-terphenyl/o-carborane building block: applications in phosphine ligand design.

    PubMed

    Lugo, Christopher A; Moore, Curtis E; Rheingold, Arnold L; Lavallo, Vincent

    2015-03-01

    A hybrid terphenyl/o-carborane ligand building block is synthesized by the reaction of m-terphenylalkyne with B10H14. This sterically demanding substituent can be installed into ligands, as demonstrated by the preparation of carboranylphosphine. The bulky phosphine reacts with [ClRh(CO)2]2 to produce monophosphine complex ClRhL(CO)2, which subsequently extrudes CO under vacuum to afford the dimeric species [ClRhL(CO)]2. The latter complex does not react with excess phosphine and is resistant toward cyclometalation, which is in contrast to related o-carborane phosphine complexes. Data from a single-crystal X-ray diffraction study are utilized to quantify the steric impact of the ligand via the percent buried volume approach. PMID:25668570

  13. Rare Earth Metal Complexes of Bidentate Nitroxide Ligands: Synthesis and Electrochemistry.

    PubMed

    Kim, Jee Eon; Bogart, Justin A; Carroll, Patrick J; Schelter, Eric J

    2016-01-19

    We report rare earth metal complexes with tri- and bidentate ligands including strongly electron-donating nitroxide groups. The tridentate ligand 1,3,5-tris(2'-tert-butylhydroxylaminoaryl)benzene (H3arene-triNOx) was complexed to cerium(IV) in a 2:1 ligand-to-metal stoichiometry as Ce(Harene-triNOx)2 (1). Cyclic voltammetry of this compound showed stabilization of the tetravalent cerium cation with a Ce(IV/III) couple at E1/2 = -1.82 V versus Fc/Fc(+). On the basis of the uninvolvement of the third nitroxide group in the coordination chemistry with the cerium(IV) cation, the ligand system was redesigned toward a simpler bidentate mode, and a series of rare earth metal-arene-diNOx complexes were prepared with La(III), Ce(IV), Pr(III), Tb(III), and Y(III), [RE(arene-diNOx)2](-) ([2-RE](-), RE = La, Pr, Y, Tb) and Ce(IV)(arene-diNOx)2, where H2arene-diNOx = 1,3-bis(2'-tert-butylhydroxylaminoaryl)benzene. The core structures were isostructural throughout the series, with three nitroxide groups in η(2) binding modes and one κ(1) nitroxide group coordinated to the metal center in the solid state. In all cases except Ce(IV)(arene-diNOx)2, electrochemical analysis described two subsequent, ligand-based, quasi-reversible redox waves, indicating that a stable [N-O•] group was generated on the electrochemical time scale. Chemical oxidation of the terbium complex was performed, and isolation of the resulting complex, Tb(arene-diNOx)2·CH2Cl2 (3·CH2Cl2), confirmed the assignment of the cyclic voltammograms. Magnetic data showed no evidence of mixing between the Tb(III) states and the states of the open-shell ligand. PMID:26689656

  14. Ligand-tailored single-site silica supported titanium catalysts: Synthesis, characterization and towards cyanosilylation reaction

    SciTech Connect

    Xu, Wei; Li, Yani; Yu, Bo; Yang, Jindou; Zhang, Ying; Chen, Xi; Zhang, Guofang Gao, Ziwei

    2015-01-15

    A successive anchoring of Ti(NMe{sub 2}){sub 4}, cyclopentadiene and a O-donor ligand, 1-hydroxyethylbenzene (PEA), 1,1′-bi-2-naphthol (Binol) or 2,3-dihydroxybutanedioic acid diethyl ester (Tartrate), on silica was conducted by SOMC strategy in moderate conditions. The silica, monitored by in-situ Fourier transform infrared spectroscopy (in-situ FT-IR), was pretreated at different temperatures (200, 500 and 800 °C). The ligand tailored silica-supported titanium complexes were characterized by in-situ FT-IR, {sup 13}C CP MAS-NMR, X-ray photoelectron spectroscopy (XPS), X-ray absorption near edge structure (XANES) and elemental analysis in detail, verifying that the surface titanium species are single sited. The catalytic activity of the ligand tailored single-site silica supported titanium complexes was evaluated by a cyanosilylation of benzaldehyde. The results showed that the catalytic activity is dependent strongly on the dehydroxylation temperatures of silica and the configuration of the ligands. - Graphical abstract: The ligand-tailored silica supported “single site” titanium complexes were synthesized by SOMC strategy and fully characterized. Their catalytic activity were evaluated by benzaldehyde silylcyanation. - Highlights: • Single-site silica supported Ti active species was prepared by SOMC technique. • O-donor ligand tailored Ti surface species was synthesized. • The surface species was characterized by XPS, {sup 13}C CP-MAS NMR, XANES etc. • Catalytic activity of the Ti active species in silylcyanation reaction was evaluated.

  15. A New Biarylphosphine Ligand for the Pd-Catalyzed Synthesis of Diaryl Ethers Under Mild Conditions

    PubMed Central

    Salvi, Luca; Davis, Nicole R.; Ali, Siraj Z.; Buchwald, Stephen L.

    2011-01-01

    A new bulky biarylphosphine ligand (L8) has been developed that allows the Pd-catalyzed C–O cross-coupling of a wide range of aryl halides and phenols under milder conditions than previously possible. A direct correlation between the size of the ligand substituents in the 2′, 4′ and 6′ positions of the non-phosphine containing ring and the reactivity of the derived catalyst system was observed. Specifically, the rate of coupling increased with the size of these substituents. PMID:22182186

  16. Regulation of eumelanin / pheomelanin synthesis and visible pigmentation in melanocytes by ligands of the melanocortin 1 receptor

    PubMed Central

    Le Pape, Elodie; Wakamatsu, Kazumasa; Ito, Shosuke; Wolber, Rainer; Hearing, Vincent J.

    2008-01-01

    The production of melanin in the hair and skin is tightly regulated by the melanocortin 1 receptor (MC1R) whose activation is controlled by 2 secreted ligands, α-melanocyte stimulating hormone (αMSH) and agouti signal protein (ASP). Since melanin is extremely stable, lasting years in biological tissues, the mechanism underlying the relatively rapid decrease in visible pigmentation elicited by ASP is of obvious interest. In this study, the effects of ASP and αMSH on the regulation of melanin synthesis and on visible pigmentation were assessed in normal murine melanocytes and were compared with the quick depigmenting effect of the tyrosinase inhibitor, phenylthiourea (PTU). αMSH increased pheomelanin levels prior to increasing eumelanin content over 4 days of treatment. Conversely, ASP switched off the pigment synthesis pathway, reducing eu- and pheo- melanin synthesis within 1 day of treatment that was proportional to the decrease in tyrosinase protein level and activity. These results demonstrate that the visible depigmentation of melanocytes induced by ASP does not require the degradation of existing melanin but rather is due to the dilution of existing melanin by melanocyte turnover, which emphasizes the importance of pigment distribution to visible color. PMID:18627531

  17. Synthesis and spectral characterization of ternary mixed-vanadyl β-diketonate complexes with Schiff bases

    NASA Astrophysics Data System (ADS)

    Baranwal, Balram Prasad; Tripathi, Kiran; Singh, Alok Kumar; Tripathi, Saurabh

    2012-06-01

    A new method to synthesize some mononuclear ternary oxovanadium(IV) complexes of the general formula [VO(β-dike)(SB)] (where Hβ-dike = acetylacetone; benzoylacetone or dibenzoylmethane, HSB = Schiff bases) has been explored by stepwise substitutions of acetylacetonate ion of VO(acac)2 with Schiff bases. The substituted acetylacetone could be fractionated out with p-xylene as an azeotrope. The complexes were characterized by elemental analyses, molecular weight determinations, spectral (electronic, infrared, 1H NMR, EPR and powder XRD) studies, magnetic susceptibility measurements and cyclic voltammetry. Molar conductance measurements indicated the complexes to be non-electrolytes in nitrobenzene. Bidentate chelating nature of β-diketones and Schiff base anions in the complexes was established by infrared and NMR spectra. Molecular weight determinations confirmed mononuclear nature of the complexes. The EPR spectra illustrated coupling of the unpaired electron with 51V nucleus (I = 7/2). Cyclic voltammograms of all the complexes displayed two-step oxidation processes. The oxidation peak potential corresponded to the quasireversible one-electron oxidation process of the metal center, yielding V(V) species. Transmission electron microscopy (TEM) indicated spherical particles of ˜200 nm diameter. The synthesized complexes are mixed-ligand complexes showing a considerable hydrolytic stability in which vanadium is having coordination number 5. A square pyramidal geometry around vanadium has been assigned in all the complexes.

  18. Synthesis and spectral characterization of ternary mixed-vanadyl β-diketonate complexes with Schiff bases.

    PubMed

    Baranwal, Balram Prasad; Tripathi, Kiran; Singh, Alok Kumar; Tripathi, Saurabh

    2012-06-01

    A new method to synthesize some mononuclear ternary oxovanadium(IV) complexes of the general formula [VO(β-dike)(SB)] (where Hβ-dike=acetylacetone; benzoylacetone or dibenzoylmethane, HSB=Schiff bases) has been explored by stepwise substitutions of acetylacetonate ion of VO(acac)(2) with Schiff bases. The substituted acetylacetone could be fractionated out with p-xylene as an azeotrope. The complexes were characterized by elemental analyses, molecular weight determinations, spectral (electronic, infrared, (1)H NMR, EPR and powder XRD) studies, magnetic susceptibility measurements and cyclic voltammetry. Molar conductance measurements indicated the complexes to be non-electrolytes in nitrobenzene. Bidentate chelating nature of β-diketones and Schiff base anions in the complexes was established by infrared and NMR spectra. Molecular weight determinations confirmed mononuclear nature of the complexes. The EPR spectra illustrated coupling of the unpaired electron with (51)V nucleus (I=7/2). Cyclic voltammograms of all the complexes displayed two-step oxidation processes. The oxidation peak potential corresponded to the quasireversible one-electron oxidation process of the metal center, yielding V(V) species. Transmission electron microscopy (TEM) indicated spherical particles of ∼200 nm diameter. The synthesized complexes are mixed-ligand complexes showing a considerable hydrolytic stability in which vanadium is having coordination number 5. A square pyramidal geometry around vanadium has been assigned in all the complexes. PMID:22387685

  19. Pyrazole and Pyrazolate as Ligands in the Synthesis and Stabilization of New Palladium(II) and (III) Compounds.

    PubMed

    Estevan, Francisco; Hirva, Pipsa; Ofori, Albert; Sanaú, Mercedes; Špec, Tanja; Úbeda, MaAngeles

    2016-03-01

    The versatility of pyrazole/pyrazolate as ligands has allowed the synthesis and the structural characterization of four different types of new orthometalated palladium compounds, for which DFT calculations have been performed in order to investigate their relative stabilities. [Pd2{μ-(C6H4)PPh2}2{μ-(R,R'2pz)}2] (R = R' = H, 2a; R = Br, R' = H, 2b; R = CH3, R' = H, 2c; R = H, R' = CH3, 2d; R = Br, R' = CH3, 2e) compounds with exo-bidentate pyrazolatos are the first paddlewheel dinuclear palladium(II) compounds with pyrazolato bridging ligands described and characterized in the literature. In the process of the synthesis of 2a, a new tetranuclear intermediate compound, [Pd4{μ-(C6H4)PPh2}4(μ-pz)2(μ-OH)2] (3a), has been isolated and structurally characterized. Compounds of the general formula [Pd2{μ-(C6H4)PPh2}2Br2(R,R'2pzH)2] (R = R' = H, 4a; R = Br; R' = H, 4b; R = CH3; R' = H, 4c; R = H; R' = CH3, 4d; R = Br; R' = CH3, 4e) with pyrazoles as monodentate ligands have also been obtained, in which, according to the QTAIM analysis, additional Br···HNpz weak interactions stabilize their structure. The tetranuclear Pd2Ag2 compounds, [Pd2{μ-(C6H4)PPh2}2{μ-(R,R'2pz-Ag-R,R'2pz)}2] (R = R' = H, 5a; R = Br; R' = H, 5b; R = CH3, R' = H, 5c), showed a distorted tetrahedron disposition of the metal atoms. The QTAIM analysis revealed an enhanced stability because of additional metal-metal interactions. New palladium(III) compounds, [Pd2{μ-(C6H4)PPh2}2{μ-(R,R'2pz)}2Cl2] (R = R' = H, 6a; R = Br, R' = H, 6b) were also synthesized by oxidation of compounds 2 with PhICl2. DFT calculations highlighted their greater stability compared to that of similar compounds with N,N-donor ligands, such as formamidinatos and triazenidos. PMID:26914982

  20. Design of HIV-1 protease inhibitors with pyrrolidinones and oxazolidinones as novel P1'-ligands to enhance backbone-binding interactions with protease: synthesis, biological evaluation, and protein-ligand X-ray studies

    SciTech Connect

    Ghosh, Arun K.; Leshchenko-Yashchuk, Sofiya; Anderson, David D.; Baldridge, Abigail; Noetzel, Marcus; Miller, Heather B.; Tie, Yunfeng; Wang, Yuan-Fang; Koh, Yasuhiro; Weber, Irene T.; Mitsuya, Hiroaki

    2009-09-02

    Structure-based design, synthesis, and biological evaluation of a series of novel HIV-1 protease inhibitors are described. In an effort to enhance interactions with protease backbone atoms, we have incorporated stereochemically defined methyl-2-pyrrolidinone and methyl oxazolidinone as the P1{prime}-ligands. These ligands are designed to interact with Gly-27{prime} carbonyl and Arg-8 side chain in the S1{prime}-subsite of the HIV protease. We have investigated the potential of these ligands in combination with our previously developed bis-tetrahydrofuran (bis-THF) and cyclopentanyltetrahydrofuran (Cp-THF) as the P2-ligands. Inhibitor 19b with a (R)-aminomethyl-2-pyrrolidinone and a Cp-THF was shown to be the most potent compound. This inhibitor maintained near full potency against multi-PI-resistant clinical HIV-1 variants. A high resolution protein-ligand X-ray crystal structure of 19b-bound HIV-1 protease revealed that the P1{prime}-pyrrolidinone heterocycle and the P2-Cp-ligand are involved in several critical interactions with the backbone atoms in the S1{prime} and S2 subsites of HIV-1 protease.

  1. Spectral, redox and catalytic studies of triphenylphosphine/triphenylarsine complexes of Ru(III) with N, O donor ligands derived from 2-hydroxy-1-naphthaldehyde and primary amines.

    PubMed

    Mahalingam, V; Karvembu, R; Chinnusamy, V; Natarajan, K

    2006-07-01

    A series of new mixed ligand hexacoordinated ruthenium(III) Schiff base complexes of the type [RuX(2)(EPh(3))(2)(LL')] (X=Cl, E=P; X=Cl or Br, E=As and LL'=anion of the Schiff bases derived from the condensation of 2-hydroxy-1-naphthaldehyde with aniline, 4-chloroaniline, 2-methyl aniline and 4-methoxy aniline) are reported. All the complexes have been characterized by analytical and spectral (IR, electronic and EPR) data. The redox behavior of the complexes has also been studied. The complexes exhibit catalytic activity in the oxidation of benzyl alcohol to benzaldehyde in the presence of N-methyl morpholine-N-oxide (NMO). An octahedral structure has been proposed for all of the complexes. PMID:16330248

  2. Synthesis and Base Hydrolysis of a Cobalt(III) Complex Coordinated by a Thioether Ligand

    ERIC Educational Resources Information Center

    Roecker, Lee

    2008-01-01

    A two-week laboratory experiment for students in advanced inorganic chemistry is described. Students prepare and characterize a cobalt(III) complex coordinated by a thioether ligand during the first week of the experiment and then study the kinetics of Co-S bond cleavage in basic solution during the second week. The synthetic portion of the…

  3. Ligand-tailored single-site silica supported titanium catalysts: Synthesis, characterization and towards cyanosilylation reaction

    NASA Astrophysics Data System (ADS)

    Xu, Wei; Li, Yani; Yu, Bo; Yang, Jindou; Zhang, Ying; Chen, Xi; Zhang, Guofang; Gao, Ziwei

    2015-01-01

    A successive anchoring of Ti(NMe2)4, cyclopentadiene and a O-donor ligand, 1-hydroxyethylbenzene (PEA), 1,1‧-bi-2-naphthol (Binol) or 2,3-dihydroxybutanedioic acid diethyl ester (Tartrate), on silica was conducted by SOMC strategy in moderate conditions. The silica, monitored by in-situ Fourier transform infrared spectroscopy (in-situ FT-IR), was pretreated at different temperatures (200, 500 and 800 °C). The ligand tailored silica-supported titanium complexes were characterized by in-situ FT-IR, 13C CP MAS-NMR, X-ray photoelectron spectroscopy (XPS), X-ray absorption near edge structure (XANES) and elemental analysis in detail, verifying that the surface titanium species are single sited. The catalytic activity of the ligand tailored single-site silica supported titanium complexes was evaluated by a cyanosilylation of benzaldehyde. The results showed that the catalytic activity is dependent strongly on the dehydroxylation temperatures of silica and the configuration of the ligands.

  4. Synthesis and anti-fungicidal activity of some transition metal complexes with benzimidazole dithiocarbamate ligand

    NASA Astrophysics Data System (ADS)

    Mohamed, Gehad G.; Ibrahim, Nasser A.; Attia, Hanaa A. E.

    2009-04-01

    Seven transition metal complexes of benzimidazole ligand (HL) are reported and characterized based on elemental analyses, IR, solid reflectance, magnetic moment, molar conductance and thermal analyses (TGA and DTA). From the obtained data, the complexes were proposed to have the general formulae [MX 2(HL)(H 2O)]· yH 2O, where M = Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cr(III); X = Cl -, SO 42- and y = 0-4. The molar conductance data revealed that all the metal chelates were non-electrolytes. From the magnetic and solid reflectance spectra, it was found that the geometrical structure of these complexes is octahedral. The thermal behaviour of these chelates showed that the hydrated complexes loss water molecules of hydration in the first step followed immediately by decomposition of the anions and ligand molecules in the subsequent steps. Fungicidal activity of the prepared complexes and free ligand was evaluated against three soil borne fungi. Data obtained showed the higher biological activity of the prepared complexes than the parent Schiff base ligand. Formulation of the most potent complex was carried out in the form of 25% WP. Fungicidal activity of the new formulation was evaluated and compared with the standard fungicide Pencycuron (Monceren 25% WP). In most cases, the new formulation possessed higher fungicidal activity than the standard fungicide under the laboratory conditions.

  5. Synthesis of triple-stranded complexes using bis(dipyrromethene) ligands.

    PubMed

    Zhang, Zhan; Dolphin, David

    2010-12-20

    The reaction of an α-free, β,β'-linked bis(dipyrromethene) ligand with Fe(3+) or Co(3+) led to noninterconvertible triple-stranded helicates and mesocates. In the present context, a stable α-free ligand 2 has been developed and complexation of ligands 1 and 2 with diamagnetic Co(3+), Ga(3+), and In(3+) has been studied. The triple-stranded M(2)1(3) (M = Ga, In) and M(2)2(3) (M = Co, Ga, In) complexes were characterized using matrix-assisted laser desorption ionization time-of-flight spectrometry, (1)H NMR and UV-vis spectroscopy, and X-ray crystallography. Again, the (1)H NMR analysis showed that both the triple-stranded helicates and mesocates were generated in this metal-directed assembly. Consistent with our previous finding on coordinatively inert Co(3+) complexes, variable-temperature NMR spectroscopy indicated that the triple-stranded helicate and mesocate of labile In(3+) did not interconvert in solution, either. However, the diastereoselectivity of the M(2)2(3) complexes was found to improve with an increase in the reaction temperature. Taken together, this study complements the coordination chemistry of poly(dipyrromethene) ligands and provides further insight into the formation of helicates versus mesocates. PMID:21070002

  6. Docking, synthesis, and NMR studies of mannosyl trisaccharide ligands for DC-SIGN lectin.

    PubMed

    Reina, José J; Díaz, Irene; Nieto, Pedro M; Campillo, Nuria E; Páez, Juan A; Tabarani, Georges; Fieschi, Franck; Rojo, Javier

    2008-08-01

    DC-SIGN, a lectin, which presents at the surface of immature dendritic cells, constitutes nowadays a promising target for the design of new antiviral drugs. This lectin recognizes highly glycosylated proteins present at the surface of several pathogens such as HIV, Ebola virus, Candida albicans, Mycobacterium tuberculosis, etc. Understanding the binding mode of this lectin is a topic of tremendous interest and will permit a rational design of new and more selective ligands. Here, we present computational and experimental tools to study the interaction of di- and trisaccharides with DC-SIGN. Docking analysis of complexes involving mannosyl di- and trisaccharides and the carbohydrate recognition domain (CRD) of DC-SIGN have been performed. Trisaccharides Manalpha1,2[Manalpha1,6]Man 1 and Manalpha1,3[Manalpha1,6]Man 2 were synthesized from an orthogonally protected mannose as a common intermediate. Using these ligands and the soluble extracellular domain (ECD) of DC-SIGN, NMR experiments based on STD and transfer-NOE were performed providing additional information. Conformational analysis of the mannosyl ligands in the free and bound states was done. These studies have demonstrated that terminal mannoses at positions 2 or 3 in the trisaccharides are the most important moiety and present the strongest contact with the binding site of the lectin. Multiple binding modes could be proposed and therefore should be considered in the design of new ligands. PMID:18633532

  7. Synthesis, Structures, and Reactions of Manganese Complexes Containing Diphosphine Ligands With Pendant Amines

    SciTech Connect

    Welch, Kevin D.; Dougherty, William G.; Kassel, W. S.; DuBois, Daniel L.; Bullock, R. Morris

    2010-10-01

    Addition of the pendant amine ligand PNRP (PNRP = Et2PCH2NRCH2PEt2; R = Me, Ph, n-Bu) to Mn(CO)5Br gives fac-Mn(PNRP)(CO)3Br. Photolysis of fac-Mn(PNRP)(CO)3Br with dppm [dppm = 1,2-bis(diphenylphosphino)methane] provides mixed bis(diphosphine) complexes, trans-Mn(PNRP)(dppm)(CO)(Br). Reaction of trans-Mn(PNRP)(dppm)(CO)(Br) with LiAlH4 leads to trans-Mn(PNRP)(dppm)(CO)(H). The crystal structure of trans-Mn(PNMeP)(dppm)(CO)(H) determined by x-ray diffraction shows an unusual distortion of the Mn-H towards one C-H of the dppm ligand, resulting in an H Mn CO angle of 155(1)° and C H • • • H Mn distance of 2.10(3) Å. Mn(P2PhN2Bn)(dppm)(CO)(H) [P2PhN2Bn = 1, 5-diphenyl-3,7-dibenzyl-1,5-diaza-3,7-diphosphacyclooctane] can be prepared in a similar manner; its structure has one chelate ring in a chair conformation and the second in a boat conformation. The boat-conformer ring directs the nitrogen of the ring towards the carbonyl ligand, and the N • • • C distance between one N of the P2PhN2Bn ligand and CO is 3.171(4) Å, indicating a weak interaction between the N of the pendant amine and the CO ligand. Reaction of NaBArF4 (ArF = = 3,5-bis(trifluoromethyl)phenyl) with Mn(P P)(dppm)(CO)(Br) produces the cations [Mn(P P)(dppm)(CO)]+. The crystal structure of [Mn(PNMeP)(dppm)(CO)][BArF4] shows two very weak agostic interactions between C-H bonds on the phenyl ring and the Mn. The cationic complexes [Mn(P P)(dppm)(CO)]+ react with H2 to form dihydrogen complexes [Mn(H2)(P P)(dppm)(CO)]+ (Keq = 1 - 90 atm-1 in fluorobenzene, for a series of different P P ligands). Similar equilibria with N2 produce [Mn(N2)(P P)(dppm)(CO)]+ (Keq generally 1-3.5 atm-1 in fluorobenzene). This work was supported by the US Department of Energy Basic Energy Sciences' Chemical Sciences, Geosciences & Biosciences Division. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

  8. Novel sulfonanilide analogs decrease aromatase activity in breast cancer cells: synthesis, biological evaluation, and ligand-based pharmacophore identification.

    PubMed

    Su, Bin; Tian, Ran; Darby, Michael V; Brueggemeier, Robert W

    2008-03-13

    Aromatase converts androgens to estrogens and is a particularly attractive target in the treatment of estrogen receptor positive breast cancer. Previously, the COX-2 selective inhibitor nimesulide and analogs decreased aromatase expression and enzyme activity independent of COX-2 inhibition. In this manuscript, a combinatorial approach was used to generate diversely substituted novel sulfonanilides by parallel synthesis. Their pharmacological evaluation as agents for suppression of aromatase activity in SK-BR-3 breast cancer cells was extensively explored. A ligand-based pharmacophore model was elaborated for selective aromatase modulation (SAM) using the Catalyst HipHop algorithms. The best qualitative model consisted of four features: one aromatic ring, two hydrogen bond acceptors, and one hydrophobic function. Several lead compounds have also been tested in aromatase transfected MCF-7 cells, and they significantly suppressed cellular aromatase activity. The results suggest that both genomic and nongenomic mechanisms of these compounds are involved within the aromatase suppression effect. PMID:18271519

  9. Ligand-Enabled, Copper-Catalyzed Regio- and Stereoselective Synthesis of Trialkylsubstituted Alkenylboronates from Unactivated Internal Alkynes.

    PubMed

    Itoh, Taisuke; Shimizu, Yohei; Kanai, Motomu

    2016-06-22

    We report the first copper-catalyzed regio- and stereoselective borylalkylation of dialkylsubstituted internal alkynes with bis(pinacolato)diboron and alkyl halides. A catalytically generated borylcopper species containing a novel π-accepting N-heterocyclic carbene ligand chemoselectively reacted with unactivated internal alkynes over alkyl halides. The intermediate alkenylcopper species subsequently reacted with alkyl halides, affording the desired products. The copper catalyst differentiated steric demands between the two aliphatic substituents on the C≡C triple bond of the alkyne substrates to exhibit high regioselectivity from a wide range of alkyne/alkyl halide combinations. This method is useful for the straightforward synthesis of trialkylsubstituted alkenylboronates, i.e., versatile precursors for tetrasubstituted alkenes containing three or four different alkylsubstituents, which are difficult to synthesize by other methods. PMID:27269988

  10. The synthesis and pH-dependent behaviour of Re(CO)3 conjugates with diimine phenolic ligands

    PubMed Central

    Chanawanno, Kullapa; Engle, James T.; Le, Kevin X.; Herrick, Richard S.

    2013-01-01

    In this report we present a study of a series of Re(CO)3 pyridineimine complexes with pendant phenol groups. We investigated the effects of the position of the phenol hydroxyl group (para, meta or ortho to the imine) on the steric and electronic characteristics of a series of Re(CO)3X(pyca-C6H4OH) compounds, where X = Cl, Br and pyca = pyridine-2-carbaldehyde imine. These compounds can be generated either via ligand synthesis followed by metal chelation (compound 4) or via a one-pot method (compounds 2, 3, 5 and 6). All six compounds show striking differences in pH-dependent UV-visible absorption based on the position of the phenol hydroxyl group. PMID:23903568

  11. Effect of Methamphetamine on Spectral Binding, Ligand Docking and Metabolism of Anti-HIV Drugs with CYP3A4

    PubMed Central

    Ande, Anusha; Wang, Lei; Vaidya, Naveen K.; Li, Weihua; Kumar, Santosh; Kumar, Anil

    2016-01-01

    Cytochrome P450 3A4 (CYP3A4) is the major drug metabolic enzyme, and is involved in the metabolism of antiretroviral drugs, especially protease inhibitors (PIs). This study was undertaken to examine the effect of methamphetamine on the binding and metabolism of PIs with CYP3A4. We showed that methamphetamine exhibits a type I spectral change upon binding to CYP3A4 with δAmax and KD of 0.016±0.001 and 204±18 μM, respectively. Methamphetamine-CYP3A4 docking showed that methamphetamine binds to the heme of CYP3A4 in two modes, both leading to N-demethylation. We then studied the effect of methamphetamine binding on PIs with CYP3A4. Our results showed that methamphetamine alters spectral binding of nelfinavir but not the other type I PIs (lopinavir, atazanavir, tipranavir). The change in spectral binding for nelfinavir was observed at both δAmax (0.004±0.0003 vs. 0.0068±0.0001) and KD (1.42±0.36 vs.2.93±0.08 μM) levels. We further tested effect of methamphetamine on binding of 2 type II PIs; ritonavir and indinavir. Our results showed that methamphetamine alters the ritonavir binding to CYP3A4 by decreasing both the δAmax (0.0038±0.0003 vs. 0.0055±0.0003) and KD (0.043±0.0001 vs. 0.065±0.001 nM), while indinavir showed only reduced KD in presence of methamphetamine (0.086±0.01 vs. 0.174±0.03 nM). Furthermore, LC-MS/MS studies in high CYP3A4 human liver microsomes showed a decrease in the formation of hydroxy ritonavir in the presence of methamphetamine. Finally, CYP3A4 docking with lopinavir and ritonavir in the absence and presence of methamphetamine showed that methamphetamine alters the docking of ritonavir, which is consistent with the results obtained from spectral binding and metabolism studies. Overall, our results demonstrated differential effects of methamphetamine on the binding and metabolism of PIs with CYP3A4. These findings have clinical implication in terms of drug dose adjustment of antiretroviral medication, especially with ritonavir

  12. Synthesis and characterization of three-layered zinc phosphites containing tert-octylamine molecules with template and ligand roles

    SciTech Connect

    Wang, Chih-Min; Chiu, Cheng-Wei; Lin, Hsiu-Mei; Lii, Kwang-Hwa

    2013-08-15

    Three-layered zinc phosphites containing single monoamine molecules with different roles have been synthesized using hydro(solvo)thermal methods and characterized by single-crystal X-ray diffraction, thermogravimetric analysis, and infrared spectroscopy. Compound 1, (C{sub 8}H{sub 17}NH{sub 3}){sub 4}Zn{sub 3}(HPO{sub 3}){sub 5}·3H{sub 2}O, consists of 20-ring layer structures sandwiched by water molecules and protonated tert-octylamine molecules. The structure of Zn(C{sub 8}H{sub 17}NH{sub 2})(HPO{sub 3}) (compound 2) is composed of 4.8{sup 2} network structures, wherein the tert-octylamines are coordinated to the Zn atom as pendant groups. Compound 3, (C{sub 8}H{sub 17}NH{sub 3}){sub 2}Zn{sub 4}(C{sub 8}H{sub 17}NH{sub 2})(HPO{sub 3}){sub 5}, was prepared in which the amine plays a dual role as both a ligand and a countercation. In addition, compound 1 is the first layered metal phosphite with large 20-ring windows. This group of substances represents the first example of the preparation of compounds in which the reactivity of incorporated single amine molecules is varied by adjusting the synthesis conditions. - Graphical abstract: The first layered metal phosphite with large 20-ring windows, (C8H17NH3)4Zn3(HPO3)5·3H{sub 2}O (1), sandwiched by water molecules and protonated tert-octylamine molecules. Highlights: • The first example of zinc phosphites contains amine molecules with template and ligand roles. • The reactivity of single amine molecules is varied by adjusting the synthesis conditions. • Compound 1 contains the largest pore opening of 20-rings in known layered metal phosphites. • Compound 3 has dual roles of amine molecules in its structure.

  13. Synthesis and spectroscopic investigations of iron(III) complexes with chlorides and dianionic, symmetrically halogen substituted phthalocyanines as ligands.

    PubMed

    Somashekarappa, M P; Keshavayya, J; Sherigara, B S

    2003-03-01

    The synthesis of iron(III) complexes of general formula FeCl(R-pc), where R-pc are dianionic, symmetrically halogen substituted phthalocyanines at the positions 2,9,16,23 or 1,8,15,22, from the corresponding amino substituted derivatives is described (R=Cl, Br, I). The complexes are characterized by UV-visible and infrared spectra, powder X-ray diffraction and magnetic susceptibility measurements. The effect of substituents at the periphery and the basicity of the solvents used on the electronic spectra are discussed. The Q band of the electronic spectra for symmetrically halogen substituted derivatives are redshifted and the substituents at 2,9,16,23- positions are more effective in redshifting the Q bands than those at 1,8,15,22-positions. Depending upon the basicity of the solvents, the ligand-to-metal charge transfer (LMCT) transitions on Q band envelop shift to the higher energy region in the order of pyridine>DMF>DMSO. The infrared absorption signals for C-H and metal-ligand vibrations appear to be sharper for 1,8,15,22 substituted derivatives than for 2,9,16,23 substituted ones. PMID:12609638

  14. Metal-organic coordination architectures of azole heterocycle ligands bearing acetic acid groups: Synthesis, structure and magnetic properties

    SciTech Connect

    Hu Bowen; Zhao Jiongpeng; Yang Qian; Hu Tongliang; Du Wenping; Bu Xianhe

    2009-10-15

    Four new coordination complexes with azole heterocycle ligands bearing acetic acid groups, [Co(L{sup 1}){sub 2}]{sub n} (1), [CuL{sup 1}N{sub 3}]{sub n} (2), [Cu(L{sup 2}){sub 2}.0.5C{sub 2}H{sub 5}OH.H{sub 2}O]{sub n} (3) and [Co(L{sup 2}){sub 2}]{sub n} (4) (here, HL{sup 1}=1H-imidazole-1-yl-acetic acid, HL{sup 2}=1H-benzimidazole-1-yl-acetic acid) have been synthesized and structurally characterized. Single-crystal structure analysis shows that 3 and 4 are 2D complexes with 4{sup 4}-sql topologies, while another 2D complex 1 has a (4{sup 3}){sub 2}(4{sup 6})-kgd topology. And 2 is a 3D complex composed dinuclear mu{sub 1,1}-bridging azido Cu{sup II} entities with distorted rutile topology. The magnetic properties of 1 and 2 have been studied. - Graphical Abstract: The synthesis, crystal structure, and magnetic properties of the new coordination complexes with azole heterocycle ligands bearing acetic acid groups are reported.

  15. Titanium(IV) catalysts with ancillary imino-spiroketonato ligands: synthesis, structure and olefin polymerization.

    PubMed

    Ma, Yuguo; Lobkovsky, Emil B; Coates, Geoffrey W

    2015-07-21

    New titanium(IV) complexes having two bidentate β-iminoethyl-spiro[4,5]decan-6-onato ligands with various N-aryl substituents have been synthesized. X-ray crystal structure analysis reveals that these titanium complexes all exhibit a C2-symmetric conformation with a distorted octahedral geometry, although the specific orientation of the ligands around the titanium center varies with the identity of the N-aryl moiety. Upon activation with methylaluminoxane (MAO), these complexes catalyze the polymerization of ethylene and propylene. In the case of ethylene, most complexes exhibit the characteristics of a living polymerization between 0 °C and 25 °C, producing polyethylenes with narrow molecular weight distributions and number average molecular weights up to 100,000 g/mol. Depending on the N-aryl substituents, polymerizations of propylene result in products with tacticity ranging from slightly syndiotactic to slightly isotactic. PMID:25984908

  16. Imino sulfinamidines: synthesis and coordination chemistry of a novel class of chiral bidentate ligands.

    PubMed

    Barrett, Anthony G M; Gray, Andrew A; Hill, Michael S; Hitchcock, Peter B; Procopiou, Panayiotis A; White, Andrew J P

    2006-04-17

    The new imino sulfinamidine ligand PhS(NHt-Bu)=NC(Me)=N(C6H3-2,6-iPr2), LH (11) was synthesized from N-(2,6-diisopropylphenyl)acetamidine (9) and N-tert-butyl phenylsulfinimidoyl chloride (10). Reaction of LH (11) with ZnEt2 or AlMe3 gave the complexes LZnEt (12) and LAlMe2 (13), respectively. The structures of 12 and 13 were determined by X-ray diffraction and were shown to contain L as a kappa2-N1,N5 bidentate ligand in a six-membered chelate. Formation of the magnesium complex (LMgN(TMS)2 x L2Mg) (14) from 11, MgI2, and KN(SiMe3)2 highlighted a secondary coordination mode of L, binding through the sulfinamidine nitrogens in a four-membered chelate. PMID:16602794

  17. Synthesis and Characterization of Aluminum Complexes of Redox-Active Pyridyl Nitroxide Ligands.

    PubMed

    Poitras, Andrew M; Bogart, Justin A; Cole, Bren E; Carroll, Patrick J; Schelter, Eric J; Graves, Christopher R

    2015-11-16

    The aluminum complexes ((R)pyNO(-))2AlCl ((R)pyNO(-) = N-tert-butyl-N-(2-pyridyl)nitroxyl; R = H (1), CH3 (2), CF3 (3)) were prepared in 80-98% yield through the protonolysis reaction between the pyridyl hydroxylamine ligand precursors (R)pyNOH and dimethylaluminum chloride. Complex 1 was also prepared using a salt metathesis route in 92% yield. Complexes 1-3 were characterized using (1)H and (13)C NMR spectroscopies. Single-crystal X-ray diffraction analysis of the complexes revealed that 1-3 are isostructural, with the Al(III) cation in all cases being five coordinate with distorted square pyramidal geometries. The geometry of complex 1 was studied using DFT, which showed primarily ligand-based frontier molecular orbitals. Reaction of 1 with NaOt-Bu gave (pyNO(-))2AlOt-Bu (4), while reaction of 1 with AgBPh4 gave [(pyNO(-))2Al(THF)2][BPh4] (5) in 54% and 87% yields, respectively. Compounds 4 and 5 were both characterized using (1)H and (13)C NMR spectroscopies and compound 5 by X-ray diffraction. Complexes 1-5 were also characterized by UV-vis electronic absorption spectroscopy and electrochemistry. The cyclic voltammograms of the complexes show two separate oxidation process, the potentials of which are dependent on both the substitution pattern of the (R)pyNO(-) ligands and the anion that completes the aluminum coordination sphere. A correlation was determined between the chemical shift of the t-Bu of the (R)pyNO(-) ligand in the (1)H NMR spectroscopy and the potentials of the redox events for complexes 1-4. PMID:26513133

  18. Synthesis and Characterization of Paramagnetic Tungsten Imido Complexes Bearing α-Diimine Ligands.

    PubMed

    Tanahashi, Hiromasa; Ikeda, Hideaki; Tsurugi, Hayato; Mashima, Kazushi

    2016-02-15

    Tungsten imido complexes bearing a redox-active ligand, such as N,N'-bis(2,6-diisopropylphenyl)-1,4-diaza-2,3-dimethyl-1,3-butadiene (L1), N,N'-bis(2,6-diisopropylphenyl)-1,4-diaza-1,3-butadiene (L2), and 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene (L3), were prepared by salt-free reduction of W(═NC6H3-2,6-(i)Pr2)Cl4 (1) using 1-methyl-3,6-bis(trimethylsilyl)-1,4-cyclohexadiene (MBTCD) followed by addition of the corresponding redox-active ligands. In the initial stage, reaction of W(═NC6H3-2,6-(i)Pr2)Cl4 with MBTCD afforded a tetranuclear W(V) imido cluster, [W(═NC6H3-2,6-(i)Pr2)Cl3]4 (2), which served as a unique precursor for introducing redox-active ligands to the tungsten center to give the corresponding mononuclear complexes with a general formula of W(═NC6H3-2,6-(i)Pr2)Cl3(L) (3, L = L1; 4, L = L2; and 6, L = L3). X-ray analyses of complexes 3 and 6 revealed a neutral coordination mode of L1 and L3 to the tungsten in solid state, while the electron paramagnetic resonance (EPR) spectra of 3 and 4 clarified that a radical was predominantly located on the tungsten center supported by neutral L1 or L2, and the EPR spectra of complex 6 indicated that a radical was delocalized over both the tungsten center and the monoanionic redox-active ligand L3. PMID:26841126

  19. Palladium(II) complexes featuring a mixed phosphine-pyridine-iminophosphorane pincer ligand: synthesis and reactivity.

    PubMed

    Cheisson, Thibault; Auffrant, Audrey

    2016-02-01

    An original mixed ligand (labelled L) of formula PPh2-CH2-Pyr-CH2-N[double bond, length as m-dash]PPh3, combining a pyridine core with phosphine and iminophosphorane, was synthesised. Its coordination with palladium(II) centers was studied. With [Pd(COD)Cl2], a cationic complex [LPdCl](Cl) 1, where L is coordinated in the pincer mode, was obtained. Chloride abstraction with silver salt in the presence of pyridine generated the dicationic complex [LPd(py)](BF4)2 (2). When reacting with a base such as potassium hexamethyldisilazane (KHMDS), 1 gave the neutral complex 3 [L*PdCl], wherein the benzylic position alpha to phosphine was selectively deprotonated, which induced dearomatisation of the pyridine ring. A similar complex [L*Pd(CH3)] (4) was obtained upon a reaction of [Pd(CH3)2(TMEDA)] and Lvia the departure of methane. Neutral complexes with the deprotonated ligand such as 3 yielded in the presence of deuterated methanol the corresponding deuterated complex, showing that the protonation is reversible with this ligand. Finally, upon attempting to dealkylate complex 4 using B(C6F5)3, an unexpected zwitterionic borated complex 5, resulting from the formation of a C-B bond in the benzylic position with restoration of the aromatic character of the pyridine, was isolated. Interestingly, when the metal was introduced after the ligand interacted with the borane reagent, another palladium complex formed, namely, [LPdMe][MeB(C6F5)3], originating from methyl abstraction. PMID:26419539

  20. Synthesis, characterization luminiscence studies and microbial activity of ethylenediamine ruthenium (II) complexes with dipyridophenazine ligands.

    PubMed

    Shilpa, Mynam; Nagababu, Penumaka; Kumar, Y Praveen; Latha, J Naveena Lavanya; Reddy, M Rajender; Karthikeyan, K S; Gabra, Nazar Md; Satyanarayana, Sirasani

    2011-05-01

    Three symmetric ligands 7-methyl dipyrido-[3,2-a;2',3'-c]phenazine (dppz-CH(3)), 7-nitro dipyrido-[3,2-a;2',3'-c]phenazine (dppz-NO(2)) and benzo[i]dipyrido-[3,2-a;2',3'-c]phenazine (dppn) and their ruthenium(II) complexes [Ru(en)(2)(L)][ClO(4)](2) (en= ethylenediamine), L= dppz-CH(3), dppz-NO(2) and dppn have been synthesized and characterized by IR, (1)H, (13)C NMR and Mass spectra. The interactions of these complexes with calf thymus DNA have been investigated by spectrophotometric, spectrofluorimetric, circular dichroism, viscosity and thermal denaturation studies. As the planar extension of the intercalative ligand increases, the interaction of the complex with DNA increases, indicating that the size and shape of the intercalalative ligand has a marked effect on the strength of interaction. The plot of log K versus log [Na(+)] yield a slope of -1.26, -1.53, -1.60 for the complexes 1, 2 and 3 respectively. These three complexes have been found to promote the cleavage of plasmid pBR 322 DNA upon irradiation. PMID:21181246

  1. Zinc (II) complex with a cationic Schiff base ligand: Synthesis, characterization, and biological studies

    NASA Astrophysics Data System (ADS)

    Lee, Sze Koon; Tan, Kong Wai; Ng, Seik Weng; Ooi, Kah Kooi; Ang, Kok Pian; Abdah, Md Akim

    2014-03-01

    A cationic Schiff base ligand, TSB (L) and its Zn (II) complex (1) were synthesized and characterized by using CHN, 1H-NMR, FT-IR, UV, LC-MS, and X-ray methods. Their ability to inhibit topoisomerase I, DNA cleavage activities, and cytotoxicity were studied. X-ray diffraction study shows that the mononuclear complex 1 is four coordinated with distorted tetrahedral geometry. The singly deprotonated Schiff base ligand L acts as a bidentate ON-donor ligand. Complexation of L increases the inhibitory strength on topoisomerase I activity. Complex 1 could fully inhibit topoisomerase I activity at 250 μM, while L did not show any inhibitory effect on topoisomerase I activity. In addition, L and complex 1 could cleave pBR322 DNA in a concentration and time dependent profile. Surprisingly, L has better DNA cleavage activity than complex 1. The cleavage of DNA by complex 1 is altered in the presence of hydrogen peroxide. Furthermore, L and complex 1 are mildly cytotoxic towards human ovarian cancer A2780 and hepatocellular carcinoma HepG2.

  2. Synthesis and Characterization of New Bivalent Agents as Melatonin- and Histamine H3-Ligands

    PubMed Central

    Pala, Daniele; Scalvini, Laura; Lodola, Alessio; Mor, Marco; Flammini, Lisa; Barocelli, Elisabetta; Lucini, Valeria; Scaglione, Francesco; Bartolucci, Silvia; Bedini, Annalida; Rivara, Silvia; Spadoni, Gilberto

    2014-01-01

    Melatonin is an endogenous molecule involved in many pathophysiological processes. In addition to the control of circadian rhythms, its antioxidant and neuroprotective properties have been widely described. Thus far, different bivalent compounds composed by a melatonin molecule linked to another neuroprotective agent were synthesized and tested for their ability to block neurodegenerative processes in vitro and in vivo. To identify a novel class of potential neuroprotective compounds, we prepared a series of bivalent ligands, in which a prototypic melatonergic ligand is connected to an imidazole-based H3 receptor antagonist through a flexible linker. Four imidazolyl-alkyloxy-anilinoethylamide derivatives, characterized by linkers of different length, were synthesized and their binding affinity for human MT1, MT2 and H3 receptor subtypes was evaluated. Among the tested compounds, 14c and 14d, bearing a pentyl and a hexyl linker, respectively, were able to bind to all receptor subtypes at micromolar concentrations and represent the first bivalent melatonergic/histaminergic ligands reported so far. These preliminary results, based on binding affinity evaluation, pave the way for the future development of new dual-acting compounds targeting both melatonin and histamine receptors, which could represent promising therapeutic agents for the treatment of neurodegenerative pathologies. PMID:25222552

  3. Neutral-ligand complexes of bis(imino)pyridine iron: synthesis, structure, and spectroscopy.

    PubMed

    Bart, Suzanne C; Lobkovsky, Emil; Bill, Eckhard; Wieghardt, Karl; Chirik, Paul J

    2007-08-20

    A family of bis(imino)pyridine iron neutral-ligand derivatives, ((iPr)PDI)FeL(n) ((iPr)PDI = 2,6-(2,6-iPr2-C6H3N=CMe)2C6H3N), has been synthesized from the corresponding bis(dinitrogen) complex, ((iPr)PDI)Fe(N2)2. When L is a strong-field ligand such as tBuNC or a chelating alkyl diphosphine such as DEPE (DEPE = 1,2-bis(diethylphosphino)ethane), a five-coordinate, diamagnetic compound results with no spectroscopic evidence for mixing of paramagnetic states. Reducing the field strength of the neutral donor to principally sigma-type ligands such as tBuNH2 or THT (THT = tetrahydrothiophene) also yielded diamagnetic compounds. However, the 1H NMR chemical shifts of the in-plane bis(imino)pyridine hydrogens exhibit a large chemical shift dispersion indicative of temperature-independent paramagnetism (TIP) arising from mixing of an S = 1 excited state via spin-orbit coupling. Metrical data from X-ray diffraction establish bis(imino)pyridine chelate reduction for each structural type, while Mössbauer parameters and NMR spectroscopic data differentiate the spin states of the iron and identify contributions from paramagnetic excited states. PMID:17655227

  4. Synthesis and characterization of a chiral, aza-15-crown-5-functionalized ferrocenyldiphosphine ligand for asymmetric catalysis

    SciTech Connect

    Landis, C.R.; Sawyer, R.A.; Somsook, E.

    2000-03-20

    A chiral ferrocenyldiphosphine ligand that is functionalized with an aza crown ether, (S)-1-[(R)-1{prime},2-bis(diphenylphosphino)ferroceny]ethyl-1-aza-2,3-benzo-15-crown-5(1), has been synthesized. Both the resolved and racemic ligands react rapidly with Pt(II) precursors to form stable metal-ligand adducts; the complexes PtMeI(rac-1) and PtMe{sub 2}(rac-1) have been characterized crystallographically. Reaction of rac-1 with [Rh(NBD){sub 2}]OTf yields [Rh(NBD)(rac-1)]OTf. The three-dimensional solution structure of [Rh(NBD)(rac-1)]OTf has been determined by NOESY experiments and analysis using the two-dimensional conformer population analysis algorithm (2DCPA). The NOESY data reveal rapid, pairwise chemical exchange between vinyl protons. The complex [Rh(NBD)(rac-1)]OTf is a catalyst precursor for hydrogenation reactions. However, the authors demonstrate that the liability of the aza crown ether may limit the ability of these catalysts to control selectivity via secondary interactions.

  5. Dinuclear gold(I) complexes of bridging bidentate carbene ligands: synthesis, structure and spectroscopic characterisation.

    PubMed

    Barnard, Peter J; Baker, Murray V; Berners-Price, Susan J; Skelton, Brian W; White, Allan H

    2004-04-01

    Eight dinuclear Au(i)-carbene complexes have been synthesized from various imidazolium-linked cyclophanes and related acyclic bis(imidazolium) salts, by treatment of the imidazolium salts with [Au(i)(SMe(2))Cl] in the presence of a carboxylate base. Single crystal structural studies showed that the Au(i)-carbene compounds contain dinuclear (AuL)(2) cations in which a pair of gold(i) centres are linked by a pair of bridging dicarbenoid ligands. Interestingly, the structural studies revealed short AuAu contacts of 3.0485(3)[Angstrom] and 3.5425(6)[Angstrom] in two of these complexes. NMR studies showed that the (AuL)(2) cations constructed from the cyclophane-based ligands retain a relatively rigid structure in solution, whilst those of the non-cyclophane ligand systems are fluxional in solution. The electronic absorption and emission spectra of the complexes in solution at room temperature were recorded and the complex with the shortest AuAu contact was found to emit intensely at 400 nm and more weakly at 780 nm upon excitation at 260 nm. The compounds with longer AuAu separations were not emissive under these conditions. PMID:15252682

  6. Synthesis and electronic structure determination of uranium(vi) ligand radical complexes.

    PubMed

    Herasymchuk, Khrystyna; Chiang, Linus; Hayes, Cassandra E; Brown, Matthew L; Ovens, Jeffrey S; Patrick, Brian O; Leznoff, Daniel B; Storr, Tim

    2016-08-01

    Pentagonal bipyramidal uranyl (UO2(2+)) complexes of salen ligands, N,N'-bis(3-tert-butyl-(5R)-salicylidene)-1,2-phenylenediamine, in which R = (t)Bu (1a), OMe (1b), and NMe2 (1c), were prepared and the electronic structure of the one-electron oxidized species [1a-c]+ were investigated in solution. The solid-state structures of 1a and 1b were solved by X-ray crystallography, and in the case of 1b an asymmetric UO2(2+) unit was found due to an intermolecular hydrogen bonding interaction. Electrochemical investigation of 1a-c by cyclic voltammetry showed that each complex exhibited at least one quasi-reversible redox process assigned to the oxidation of the phenolate moieties to phenoxyl radicals. The trend in redox potentials matches the electron-donating ability of the para-phenolate substituents. The electron paramagnetic resonance spectra of cations [1a-c]+ exhibited gav values of 1.997, 1.999, and 1.995, respectively, reflecting the ligand radical character of the oxidized forms, and in addition, spin-orbit coupling to the uranium centre. Chemical oxidation as monitored by ultraviolet-visible-near-infrared (UV-vis-NIR) spectroscopy afforded the one-electron oxidized species. Weak low energy intra-ligand charge transfer (CT) transitions were observed for [1a-c]+ indicating localization of the ligand radical to form a phenolate/phenoxyl radical species. Further analysis using density functional theory (DFT) calculations predicted a localized phenoxyl radical for [1a-c]+ with a small but significant contribution of the phenylenediamine unit to the spin density. Time-dependent DFT (TD-DFT) calculations provided further insight into the nature of the low energy transitions, predicting both phenolate to phenoxyl intervalence charge transfer (IVCT) and phenylenediamine to phenoxyl CT character. Overall, [1a-c]+ are determined to be relatively localized ligand radical complexes, in which localization is enhanced as the electron donating ability of the para

  7. Synthesis, spectral characterization, molecular modeling and antimicrobial studies of tridentate azo-dye Schiff base metal complexes

    NASA Astrophysics Data System (ADS)

    Alaghaz, Abdel-Nasser M. A.; Zayed, Mohamed E.; Alharbi, Suliman A.

    2015-03-01

    Nine mononuclear Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Pt(IV) complexes of azo-dye Schiff's base ligand were synthesized and determined by different physical techniques. All the nine metal complexes are reported using elemental analysis, molar conductance, magnetic susceptibility, IR, UV-Vis, thermal analysis and 1H NMR, 13C NMR, mass, SEM, TEM, EDX, XRD spectral studies. The molar conductance measurements of all the complexes in DMF solution correspond to non-electrolytic nature. All complexes were of the high-spin type and found to have six-coordinate octahedral geometry except the Cu(II) complex which was four coordinate, square planar. Quantum chemical calculations were performed with semi-empirical method to find the optimum geometry of the ligand and its complexes. In molecular modeling the geometries of azo-dye Schiff base ligand HL and its metal (II/III/IV) complexes were fully optimized with respect to the energy using the 6-31G basis set. These ligand and its metal complexes have also been screened for their in vitro antimicrobial activities.

  8. Ruthenium(II) carbonyl complexes containing S-methylisothiosemicarbazone based tetradentate ligand: synthesis, characterization and biological applications.

    PubMed

    Selvamurugan, Sellappan; Ramachandran, Rangasamy; Viswanathamurthi, Periasamy

    2013-10-01

    A series of hexa-coordinated ruthenium(II) complexes of the type [Ru(CO)(B)L(n)] (n = 1-4; B = PPh3, AsPh3 or Py) have been synthesized by reacting dibasic quadridentate Schiff base ligands H2L(n) (n = 1-4) with starting complexes [RuHCl(CO)(EPh3)2(B)] (E = P or As; B = PPh3, AsPh3 or Py). The synthesized complexes were characterized using elemental and various spectral studies including UV-Vis, FT-IR, NMR ((1)H, (13)C and (31)P) and mass spectroscopy. An octahedral geometry was tentatively proposed for all the complexes based on the spectral data obtained. The experiments on antioxidant activity showed that the ruthenium(II) S-methylisothiosemicarbazone Schiff base complexes exhibited good scavenging activity against various free radicals (DPPH, OH and NO). The in vitro cytotoxicity of these complexes has been evaluated by MTT assay. The results demonstrate that the complexes have good anticancer activities against selected cancer cell line, human breast cancer cell line (MCF-7) and human skin carcinoma cell line (A431). The DNA cleavage studies showed that the complexes have better cleavage of pBR 322 DNA. PMID:23780567

  9. The Impact of Surface Ligands and Synthesis Method on the Toxicity of Glutathione-Coated Gold Nanoparticles

    PubMed Central

    Harper, Bryan; Sinche, Federico; Wu, Rosina Ho; Gowrishankar, Meenambika; Marquart, Grant; Mackiewicz, Marilyn; Harper, Stacey L.

    2015-01-01

    Gold nanoparticles (AuNPs) are increasingly used in biomedical applications, hence understanding the processes that affect their biocompatibility and stability are of significant interest. In this study, we assessed the stability of peptide-capped AuNPs and used the embryonic zebrafish (Danio rerio) as a vertebrate system to investigate the impact of synthesis method and purity on their biocompatibility. Using glutathione (GSH) as a stabilizer, Au-GSH nanoparticles with identical core sizes were terminally modified with Tryptophan (Trp), Histidine (His) or Methionine (Met) amino acids and purified by either dialysis or ultracentrifugation. Au-GSH-(Trp)2 purified by dialysis elicited significant morbidity and mortality at 200 μg/mL, Au-GSH-(His)2 induced morbidity and mortality after purification by either method at 20 and 200 μg/mL, and Au-GSH-(Met)2 caused only sublethal responses at 200 μg/mL. Overall, toxicity was significantly reduced and ligand structure was improved by implementing ultracentrifugation purifications at several stages during the multi-step synthesis and surface modification of Au-GSH nanoparticles. When carefully synthesized at high purity, peptide-functionalized AuNPs showed high biocompatibility in biological systems. PMID:26213631

  10. Synthesis of Enantiopure 10-Nornaltrexones in the Search for Toll-like Receptor 4 Antagonists and Opioid Ligands

    PubMed Central

    2015-01-01

    10-Nornaltrexones (3-(cyclopropylmethyl)-4a,9-dihydroxy-2,3,4,4a,5,6-hexahydro-1H-benzofuro[3,2-e]isoquinolin-7(7aH)-one, 1) have been underexploited in the search for better opioid ligands, and their enantiomers have been unexplored. The synthesis of trans-isoquinolinone 2 (4-aH, 9-O-trans-9-methoxy-3-methyl-2,3,4,4a,5,6-hexahydro-1H-benzofuro[3,2-e]isoquinolin-7(7aH)-one) was achieved through a nonchromatographic optimized synthesis of the intermediate pyridinyl compound 12. Optical resolution was carried out on 2, and each of the enantiomers were used in efficient syntheses of the “unnatural” 4aR,7aS,12bR-(+)-1) and its “natural” enantiomer (−)-1. Addition of a 14-hydroxy (the 4a-hydroxy) group in the enantiomeric isoquinolinones, (+)- and (−)-2), gave (+)- and (−)-10-nornaltrexones. A structurally unique tetracyclic enamine, (12bR)-7,9-dimethoxy-3-methyl-1,2,3,7-tetrahydro-7,12b-methanobenzo[2,3]oxocino[5,4-c]pyridine, was found as a byproduct in the syntheses and offers a different opioid-like skeleton for future study. PMID:24773391

  11. SME@XSEDE: An automated spectral synthesis tool for stellar characterization

    NASA Astrophysics Data System (ADS)

    Hebb, Leslie; Cargile, Phillip

    2015-01-01

    Over the last decade, large scale discovery surveys like Kepler have produced vast catalogs of newly discovered extrasolar planetary systems. Most of these systems require stellar characterization of the host stars in order to derive the host star masses and completely solve for the planetary properties. Currently, there is no widely accepted and standardized method to determine fundamental parameters from stellar spectra. Here, we present a new approach to automating stellar characterization of large datasets of high resolution spectra. Our software, called SME@XSEDE, is based on one of the most widely used spectral synthesis algorithms, Spectroscopy Made Easy (SME), originally described in Valenti and Piskanov (1996). Like SME, SME@XSEDE compares an observed spectrum to synthetic model spectra derived through radiative transfer calculations for a range of stellar parameters in order to find the global stellar properties (temperature, gravity, metallicity, vsini, and individual abundances) that result in a synthetic spectrum that best matches an observed spectrum. We use the XSEDE super computer cluster to run many sets of initial guesses of stellar parameters to determine robust SME-based solutions without extensive, hands-on work. In this paper, we describe our software in detail and compare results derived from the application of SME@XSEDE to several well-studied datasets of stellar parameters including Valenti and Fischer 2005, Torres et al. 2012, and Huber et al 2013.

  12. vis.SME -- Building a Visualization Tool to Analyze and Share Spectral Synthesis Stellar Characterization

    NASA Astrophysics Data System (ADS)

    Rosario Franco, Marialis; Cargile, P.; Hebb, L.; Johnson, J. A.

    2014-01-01

    New ways of conducting research in observational and computational astronomy has led to a new focus: Big Data Astronomy. With ongoing and planned large-scale surveys including Kepler, K2, Gaia, and TESS, the field of exoplanet detection and characterization has been revolutionized by vast amounts of data leading to the confirmation of over 700 extra-solar planets. However, there continues to be a great need for innovation in data visualization and data-sharing applications to manage the science output within these large collaborations. Motivated by this, we are developing vis.SME, a new tool to visualize stellar characterization outputs from SME@XSEDE -- a recently developed spectral synthesis software that can efficiently determine temperatures, abundances, surface gravities, and rotation rates for hundreds of stars at a time. vis.SME is a web-based tool allowing optimal visualization of stellar characterization results, integration and comparison with other extant data sources, and serve as an effective way for sharing these results between collaboration members. We will present a preview of this new tool, including snapshots of its components and an example of how we are utilizing it to characterize potential Kepler exoplanet hosting stars.

  13. Configuration Control in the Synthesis of Homo- and Heteroleptic Bis(oxazolinylphenolato/thiazolinylphenolato) Chelate Ligand Complexes of Oxorhenium(V): Isomer Effect on Ancillary Ligand Exchange Dynamics and Implications for Perchlorate Reduction Catalysis.

    PubMed

    Liu, Jinyong; Wu, Dimao; Su, Xiaoge; Han, Mengwei; Kimura, Susana Y; Gray, Danielle L; Shapley, John R; Abu-Omar, Mahdi M; Werth, Charles J; Strathmann, Timothy J

    2016-03-01

    This study develops synthetic strategies for N,N-trans and N,N-cis Re(O)(LO-N)2Cl complexes and investigates the effects of the coordination spheres and ligand structures on ancillary ligand exchange dynamics and catalytic perchlorate reduction activities of the corresponding [Re(O)(LO-N)2](+) cations. The 2-(2'-hydroxyphenyl)-2-oxazoline (Hhoz) and 2-(2'-hydroxyphenyl)-2-thiazoline (Hhtz) ligands are used to prepare homoleptic N,N-trans and N,N-cis isomers of both Re(O)(hoz)2Cl and Re(O)(htz)2Cl and one heteroleptic N,N-trans Re(O)(hoz)(htz)Cl. Selection of hoz/htz ligands determines the preferred isomeric coordination sphere, and the use of substituted pyridine bases with varying degrees of steric hindrance during complex synthesis controls the rate of isomer interconversion. The five corresponding [Re(O)(LO-N)2](+) cations exhibit a wide range of solvent exchange rates (1.4 to 24,000 s(-1) at 25 °C) and different LO-N movement patterns, as influenced by the coordination sphere of Re (trans/cis), the noncoordinating heteroatom on LO-N ligands (O/S), and the combination of the two LO-N ligands (homoleptic/heteroleptic). Ligand exchange dynamics also correlate with the activity of catalytic reduction of aqueous ClO4(-) by H2 when the Re(O)(LO-N)2Cl complexes are immobilized onto Pd/C. Findings from this study provide novel synthetic strategies and mechanistic insights for innovations in catalytic, environmental, and biomedical research. PMID:26894635

  14. Synthesis of Naphthalimidedioxime Ligand-Containing Fibers for Uranium Adsorption from Seawater

    DOE PAGESBeta

    Chatterjee, Sabornie; Bryantsev, Vyacheslav S.; Brown, Suree; Johnson, J. Casey; Grant, Christopher D.; Mayes, Richard T.; Hay, Benjamin P.; Dai, Sheng; Saito, Tomonori

    2015-12-16

    Uranium exists as uranyl carbonates (primarily as [UO2(CO3)3]4-) at a low concentration of 3.3 ppb, in seawater. Due to the ocean's vast volume, the total amount of uranium in seawater has been estimated at 4.5 billion tons or nearly 1000 times more than land-based resources. This large surplus provides attractive solution to supply nuclear fuel feeds in future. However, the presence of a variety of competing metal ions and the low concentration of uranium in seawater make the extraction of uranium from seawater challenging. The goal of this work is to develop adsorbent fibers that can recover uranium from themore » slightly alkaline (pH 8.0 - 8.3) seawater. In this process, radiation-induced graft polymerization (RIGP) is used where fibers are prepared by irradiating and treating polyethylene (PE) with different bulk ratios of vinyl benzyl chloride (VBC) and methacrylic acid (MAA) or itaconic acid. Furthermore, chemical modifications of these fibers were performed via two step processes, where novel bisimidoxime ligands are incorporated into fibers. These ligands contain imidedioxime, which is known to be a uranium-philic functionality. Also, the core structures of these ligands containing three donor atoms facilitate the formation of chelates with uranyl ion in seawater. Density functional theory (DFT) calculations were performed to quantify the binding strength with the uranyl ion. The adsorbent showed moderate to high uranium (~35-50 g-U/kg adsorbent) adsorption capacity in a model seawater with a uranium concentration of 6 ppm at pH 8.0 8.3.« less

  15. Metal dicyanamide layered coordination polymers with cyanopyridine co-ligands: Synthesis, crystal structures and magnetism

    SciTech Connect

    Du Miao . E-mail: dumiao@public.tpt.tj.cn; Wang Qian; Wang Ying; Zhao Xiaojun; Ribas, Joan

    2006-12-15

    A series of metal dicyanamide (dca) coordination polymers combined with cyanopyridine (cypy) terminal co-ligands, namely, [Co{sub 2}(dca){sub 4}(4-cypy){sub 4}] {sub n} (1), [Cd(dca){sub 2}(4-cypy){sub 2}] {sub n} (2), [Fe(dca){sub 2}(3-cypy){sub 2}] {sub n} (3) and [Co(dca){sub 2}(3-cypy){sub 2}] {sub n} (4), have been synthesized at the ambient conditions. X-ray single crystal diffraction reveals that complexes 1-4 have similar metal-dca coordination layers in which the octahedral metal centers are connected by {mu} {sub 1,5}-dca linkers. Notably, three types of 3-D packing lattices are observed for these layered arrays. The thermal stabilities of such new crystalline materials have been studied by thermogravimetric analysis of mass loss. The magnetic properties of the Co{sup II} and Fe{sup II} complexes have been investigated and discussed in detail. A discrete mononuclear molecule [Cd(dca){sub 2}(pyom){sub 2}] (5) is also described, in which the chelated ligand O-methyl picolinimidate (pyom) arises from the addition of methanol solvent across the C{identical_to}N bond of 2-cypy. - Graphical abstract: A series of new metal dicyanamide complexes with cyanopyridine terminal co-ligands have been prepared and structurally determined by X-ray single-crystal diffraction. The magnetic properties of the Co{sup II} and Fe{sup II} layered coordination polymers are also discussed.

  16. Synthesis, structure and luminescence properties of lanthanide complex with a new tetrapodal ligand featuring salicylamide arms

    SciTech Connect

    Song Xueqin; Wen Xiaoguang; Liu Weisheng; Wang Daqi

    2010-01-15

    A new tetrapodal ligand 1,1,1-tetrakis{l_brace}[(2'-(2-furfurylaminoformyl))phenoxyl]methyl{r_brace}methane (L) has been prepared and their coordination chemistry with Ln{sup III} ions has been investigated. The structure of {l_brace}[Ln{sub 4}L{sub 3}(NO{sub 3}){sub 12}].H{sub 2}O{r_brace}{sub i}nfinity (Ln=Nd, Eu)] shows the binodal 4,3-connected three-dimensional interpenetration coordination polymers with topology of a (8{sup 6}){sub 3}(8{sup 3}){sub 4} notation. [DyL(NO{sub 3}){sub 3}(H{sub 2}O){sub 2}].0.5CH{sub 3}OH and [ErL(NO{sub 3}){sub 3}(H{sub 2}O) (CH{sub 3}OH)].CH{sub 3}COCH{sub 3} is a 1:1 mononuclear complex with interesting supramolecular features. The structure of [NdL(H{sub 2}O){sub 6}].3ClO{sub 4}.3H{sub 2}O is a 2:1 mononuclear complex which further self-assembled through hydrogen bond to form a three-dimensional supramolecular structures. The result presented here indicates that both subtle variation of the terminal group and counter anions can be applied in the modulation of the overall molecular structures of lanthanide complex of salicylamide derivatives due to the structure specialties of this type of ligand. The luminescence properties of the Eu{sup III} complex are also studied in detail. - Grapical Abstract: We present here a series of zero- to three-dimensional lanthanide coordination structures and luminescence properties of Eu(III) complex of a new tetrapodal ligand.

  17. Hydrothermal synthesis and structural characterization of metal-organic frameworks based on new tetradentate ligands.

    PubMed

    Liang, Yue; Yuan, Wei-Guan; Zhang, Shu-Fang; He, Zhan; Xue, Junru; Zhang, Xia; Jing, Lin-Hai; Qin, Da-Bin

    2016-01-28

    The hydrothermal reaction of two new tetradentate ligands with different metal salts of cadmium nitrate, zinc chloride, cobalt nitrate and deprotonated terephthalic acid (H2tp), isophthalic acid (H2ip), 4,4'-oxybisbenzoic acid (H2obba) in H2O/DMF or H2O/methanol gave three metal-organic frameworks (MOFs): {[Zn2(L1)(tp)(formate)2]·H2O}n (), {[Cd2(L2)(ip)2]·2H2O}n (), {[Co2(L2)(obba)2]}n () (L1 = 1,2-bis {2,6-bis [(1H-imidazol-1-yl) methyl]-4-methylphenoxy} ethane, L2 = 1,3-bis {2,6-bis [(1H-imidazol-1-yl) methyl]-4-methylphenoxy} propane). The structures of the frameworks are established by single-crystal X-ray diffraction. Compound is a three-dimensional (3D) framework with a 2-fold interpenetrated form, which exhibits a 2-nodal (3,4)-connected fsh-3,4-P21/c net with a {8(3)}2{8(5)·10} topology. Compound has a 2-nodal (4,8)-connected 3D framework where the dinuclear cadmium cluster secondary building units (SBUs) assemble with isophthalate and ligand L2 to construct a rare topological type sqc22 net with a {3(2)·5(4)}{3(4)·4(4)·5(10)·6(10)} topology. Whereas, Compound can be extended to a 2D interlocked (4,4)-connected 4,4 L28 net with the point symbol {4·6(4)·8}2{4(2)·6(4)}. L1 and L2 are tetradentate ligands with diverse linkers and display different coordination modes. In addition, the thermal stability and photochemical properties of the frameworks are also investigated. PMID:26674324

  18. Synthesis of Naphthalimidedioxime Ligand-Containing Fibers for Uranium Adsorption from Seawater

    SciTech Connect

    Chatterjee, Sabornie; Bryantsev, Vyacheslav S.; Brown, Suree; Johnson, J. Casey; Grant, Christopher D.; Mayes, Richard T.; Hay, Benjamin P.; Dai, Sheng; Saito, Tomonori

    2015-12-16

    Uranium exists as uranyl carbonates (primarily as [UO2(CO3)3]4-) at a low concentration of 3.3 ppb, in seawater. Due to the ocean's vast volume, the total amount of uranium in seawater has been estimated at 4.5 billion tons or nearly 1000 times more than land-based resources. This large surplus provides attractive solution to supply nuclear fuel feeds in future. However, the presence of a variety of competing metal ions and the low concentration of uranium in seawater make the extraction of uranium from seawater challenging. The goal of this work is to develop adsorbent fibers that can recover uranium from the slightly alkaline (pH 8.0 - 8.3) seawater. In this process, radiation-induced graft polymerization (RIGP) is used where fibers are prepared by irradiating and treating polyethylene (PE) with different bulk ratios of vinyl benzyl chloride (VBC) and methacrylic acid (MAA) or itaconic acid. Furthermore, chemical modifications of these fibers were performed via two step processes, where novel bisimidoxime ligands are incorporated into fibers. These ligands contain imidedioxime, which is known to be a uranium-philic functionality. Also, the core structures of these ligands containing three donor atoms facilitate the formation of chelates with uranyl ion in seawater. Density functional theory (DFT) calculations were performed to quantify the binding strength with the uranyl ion. The adsorbent showed moderate to high uranium (~35-50 g-U/kg adsorbent) adsorption capacity in a model seawater with a uranium concentration of 6 ppm at pH 8.0 8.3.

  19. Uranyl Sequestration: Synthesis and Structural Characterization of Uranyl Complexes with a Tetradentate Methylterephthalamide Ligand

    SciTech Connect

    Ni, Chengbao; Shuh, David; Raymond, Kenneth

    2011-03-07

    Uranyl complexes of a bis(methylterephthalamide) ligand (LH{sub 4}) have been synthesized and characterized by X-ray crystallography. The structure is an unexpected [Me{sub 4}N]{sub 8}[L(UO{sub 2})]{sub 4} tetramer, formed via coordination of the two MeTAM units of L to two uranyl moieties. Addition of KOH to the tetramer gave the corresponding monomeric uranyl methoxide species [Me{sub 4}N]K{sub 2}[LUO{sub 2}(OMe)].

  20. New Iridium Complex Coordinated with Tetrathiafulvalene Substituted Triazole-pyridine Ligand: Synthesis, Photophysical and Electrochemical Properties.

    PubMed

    Niu, Zhi-Gang; Xie, Hui; He, Li-Rong; Li, Kai-Xiu; Xia, Qing; Wu, Dong-Min; Li, Gao-Nan

    2016-01-01

    A new iridium(III) complex based on the triazole-pyridine ligand with tetrathiafulvalene unit, [Ir(ppy)2(L)]PF6 (1), has been synthesized and structurally characterized. The absorption spectra, luminescent spectra and electrochemical behaviors of L and 1 have been investigated. Complex 1 is found to be emissive at room temperature with maxima at 481 and 510 nm. The broad and structured emission bands are suggested a mixing of 3LC (3π-π*) and 3CT (3MLCT) excited states. The influence of iridium ion coordination on the redox properties of the TTF has also been investigated by cyclic voltammetry. PMID:27333555

  1. Synthesis of mixed-ligand complexes of rare-earth elements

    SciTech Connect

    Panyushkin, V.T.; Akhrimenko, N.V.

    1994-09-10

    The authors have synthesized mixed-ligand complexes of Nd(III), Sm(III), Eu(III), Tb(III), Dy(III), Ho(III), Er(III), and Yb(III) with acetylacetone (I) and unsaturated organic acids (II): maleic, fumaric, acrylic, and methacrylic. According to elemental analyses and thermogravimetric data the composition of Ln(I){sub 2}(II) {center_dot} 3H{sub 2}O does not depend on the basicity of the acid. The structure of compounds prepared was studied by IR, NMR, and luminescent spectroscopy.

  2. Synthesis and investigations of double-pharmacophore ligands for treatment of chronic and neuropathic pain

    PubMed Central

    Vardanyan, Ruben; Vijay, Gokhale; Nichol, Gary S.; Liu, Lu; Kumarasinghe, Isuru; Davis, Peg; Vanderah, Todd; Porreca, Frank; Lai, Josephine; Hruby, Victor J.

    2009-01-01

    Acids 9 a–f as possible bivalent ligands designed as a structural combination of opioid μ-agonist (Fentanyl) and NSAID (Indomethacin) activities and produced compounds which were tested as analgesics. The obtained series of compounds exhibits low affinity and activity both at opioid receptors and as cyclooxygenase (COX) inhibitors. One explanation of the weak opioid activity could be stereochemical peculiarities of these bivalent compounds which differ significantly from the fentanyl skeleton. The absence of significant COX inhibitory properties could be explained by the required substitution of an acyl fragment in the indomethacin structure for 4-piperidyl. PMID:19540763

  3. Functional Short-Bite Ligands: Synthesis, Coordination Chemistry, and Applications of N-Functionalized Bis(diaryl/dialkylphosphino)amine-type Ligands.

    PubMed

    Fliedel, Christophe; Ghisolfi, Alessio; Braunstein, Pierre

    2016-08-24

    The aim of this review is to highlight how the diversity generated by N-substitution in the well-known short-bite ligand bis(diphenylphosphino)amine (DPPA) allows a fine-tuning of the ligand properties and offers a considerable scope for tailoring the properties and applications of their corresponding metal complexes. The various N-substituents include nitrogen-, oxygen-, phosphorus-, sulfur-, halogen-, and silicon-based functionalities and directly N-bound metals. Multiple DPPA-type ligands linked through an organic spacer and N-functionalized DRPA-type ligands, in which the PPh2 substituents are replaced by PR2 (R = alkyl, benzyl) groups, are also discussed. Owing to the considerable diversity of N-functionalized DPPA-type ligands available, the applications of their mono- and polynuclear metal complexes are very diverse and range from homogeneous catalysis with well-defined or in situ generated (pre)catalysts to heterogeneous catalysis and materials science. In particular, sustained interest for DPPA-type ligands has been motivated, at least in part, by their ability to promote selective ethylene tri- or tetramerization in combination with chromium. Ligands and metal complexes where the N-substituent is a pure hydrocarbon group (as opposed to N-functionalization) are outside the scope of this review. However, when possible, a comparison between the catalytic performances of N-functionalized systems with those of their N-substituted analogs will be provided. PMID:27456550

  4. Insight into the Ligand-Mediated Synthesis of Colloidal CsPbBr3 Perovskite Nanocrystals: The Role of Organic Acid, Base, and Cesium Precursors.

    PubMed

    Pan, Aizhao; He, Bo; Fan, Xiaoyun; Liu, Zeke; Urban, Jeffrey J; Alivisatos, A Paul; He, Ling; Liu, Yi

    2016-08-23

    While convenient solution-based procedures have been realized for the synthesis of colloidal perovskite nanocrystals, the impact of surfactant ligands on the shape, size, and surface properties still remains poorly understood, which calls for a more detailed structure-morphology study. Herein we have systematically varied the hydrocarbon chain composition of carboxylic acids and amines to investigate the surface chemistry and the independent impact of acid and amine on the size and shape of perovskite nanocrystals. Solution phase studies on purified nanocrystal samples by (1)H NMR and IR spectroscopies have confirmed the presence of both carboxylate and alkylammonium ligands on surfaces, with the alkylammonium ligand being much more mobile and susceptible to detachment from the nanocrystal surfaces during polar solvent washes. Moreover, the chain length variation of carboxylic acids and amines, ranging from 18 carbons down to two carbons, has shown independent correlation to the size and shape of nanocrystals in addition to the temperature effect. We have additionally demonstrated that employing a more soluble cesium acetate precursor in place of the universally used Cs2CO3 results in enhanced processability without sacrificing optical properties, thus offering a more versatile recipe for perovskite nanocrystal synthesis that allows the use of organic acids and amines bearing chains shorter than eight carbon atoms. Overall our studies have shed light on the influence of ligand chemistry on crystal growth and stabilization of the nanocrystals, which opens the door to functionalizable perovskite nanocrsytals through surface ligand manipulation. PMID:27479080

  5. Synthesis, crystal structure and photoluminescence property of Eu/Tb MOFs with mixed polycarboxylate ligands

    NASA Astrophysics Data System (ADS)

    Yang, Lu; Zhang, Sheng; Qu, Xiaoni; Yang, Qi; Liu, Xiangyu; Wei, Qing; Xie, Gang; Chen, Sanping

    2015-11-01

    Lanthanide MOFs, [Eu(TCA)(NDC)·H2O]n (1) and [Tb(TCA)(NDC)·H2O]n (2), have been prepared with the mixed aromatic carboxylate ligands, namely, 4,4‧,4″-tricarboxytriphenylamine (H3TCA) and 1,4-naphthalenedicarboxylate (H2NDC). Single-crystal X-ray diffraction analysis reveals that isomorphic 1 and 2 present pillar-layered 3D framework that Eu/Tb(III) bond with carboxylate in various coordination fashions. Optical investigation indicates that the as-prepared compounds feature characteristic luminescence emission bands of Eu/Tb ions in the visible regions at room temperature. Moreover, compound 2 shows a relatively longer luminescence lifetime (τ=0.342 ms) and significantly enhanced quantum yield (Φoverall=11%) comparing with those of 1 (τ=0.335 ms, Φoverall=0.06%). Two Ln-MOFs (Ln=EuIII, TbIII) with mixed polycarboxylate ligands present different luminescent properties.

  6. Synthesis and Pharmacological Evaluation of α4β2 Nicotinic Ligands with a 3-Fluoropyrrolidine Nucleus.

    PubMed

    Tamborini, Lucia; Pinto, Andrea; Ettari, Roberta; Gotti, Cecilia; Fasoli, Francesca; Conti, Paola; De Micheli, Carlo

    2015-06-01

    Nicotinic acetylcholine receptors (nAChRs) play an important role in many central nervous system disorders such as Alzheimer's and Parkinson's diseases, schizophrenia, and mood disorders. The α(4)β(2) subtype has emerged as an important target for the early diagnosis and amelioration of Alzheimer's disease symptoms. Herein we report a new class of α(4)β(2) receptor ligands characterized by a basic pyrrolidine nucleus, the basicity of which was properly decreased through the insertion of a fluorine atom at the 3-position, and a pyridine ring carrying at the 3-position substituents known to positively affect affinity and selectivity toward the α(4)β(2) subtype. Derivatives 3-(((2S,4R)-4-fluoropyrrolidin-2-yl)methoxy)-5-(phenylethynyl)pyridine (11) and 3-((4-fluorophenyl)ethynyl)-5-(((2S,4R)-4-fluoropyrrolidin-2-yl)methoxy)pyridine (12) were found to be the most promising ligands identified in this study, showing good affinity and selectivity for the α(4)β(2) subtype and physicochemical properties predictive of a relevant central nervous system penetration. PMID:25882435

  7. Synthesis, characterization, DNA binding and cleavage studies of Ru(II) complexes containing oxime ligands

    NASA Astrophysics Data System (ADS)

    Chitrapriya, Nataraj; Mahalingam, Viswanathan; Zeller, Matthias; Lee, Hyosun; Natarajan, Karuppannan

    2010-12-01

    The Ru(II) precursors, [RuHCl(CO)(EPh 3) 3] (E = P or As) when reacted with some well known monoxime and dioxime ligands in ethanolic solution afforded the new complexes of the types [RuCl(CO)(EPh 3) 2L1], [RuH(CO)(EPh 3) 2L2] and [RuCl(CO)(EPh 3) 2L3] ((H 1L1) = diacetylmonoxime, (H 1L2) = dimethylglyoxime and (H 2L3) = benzoiloxime). The ligands coordinated in a bidentate chelate mode forming a five membered chelate ring. The molecular structures of two of the complexes have been determined by single crystal X-ray diffraction study. The structural determination confirms the deprotonation of the oxime function. Examination of all the complexes by cyclic voltammetry showed the occurrence of some quasi-reversible redox reactions owing to changes in the oxidation state of the central metal atoms. Structural assignments are supported by combination of IR, UV-Vis, 1H NMR and elemental analyses. In addition, the DNA binding properties and cleavage efficiency of new complexes have been tested.

  8. Expeditious Chemoenzymatic Synthesis of Homogeneous N-Glycoproteins Carrying Defined Oligosaccharide Ligands

    PubMed Central

    Ochiai, Hirofumi; Huang, Wei; Wang, Lai-Xi

    2009-01-01

    An efficient chemoenzymatic method for the construction of homogeneous N-glycoproteins was described that explores the transglycosylation activity of the endo-β-N-acetylglucosaminidase from Arthrobacter protophormiae (Endo-A) with synthetic sugar oxazolines as the donor substrates. First, an array of large oligosaccharide oxazolines were synthesized and evaluated as substrates for the Endo-A catalyzed transglycosylation using ribonuclease B as a model system. The experimental results showed that Endo-A could tolerate modifications at the outer mannose residues of the Man3GlcNAc-oxazoline core, thus allowing introduction of large oligosaccharide ligands into a protein and meanwhile preserves the natural, core N-pentasaccharide (Man3GlcNAc2) structure in the resulting glycoprotein upon transglycosylation. In addition to ligands for galectins and mannose-binding lectins, azido functionality could be readily introduced at the N-pentasaccharide (Man3GlcNAc2) core using azido-containing Man3GlcNAc oxazoline as the donor substrate. The introduction of azido functionality permits further site-specific modifications of the resulting glycoproteins, as demonstrated by the successful attachment of two copies of αGal epitopes to ribonuclease B. This study reveals a broad substrate specificity of Endo-A for transglycosylation, and the chemoenzymatic method described here points to a new avenue for a quick access to various homogeneous N-glycoproteins for structure-activity relationship studies and for biomedical applications. PMID:18803385

  9. Compact biocompatible quantum dots via RAFT-mediated synthesis of imidazole-based random copolymer ligand

    PubMed Central

    Liu, Wenhao; Greytak, Andrew B.; Lee, Jungmin; Wong, Cliff R.; Park, Jongnam; Marshall, Lisa F.; Jiang, Wen; Curtin, Peter N.; Ting, Alice Y.; Nocera, Daniel G.; Fukumura, Dai; Jain, Rakesh K.; Bawendi, Moungi G.

    2010-01-01

    We present a new class of polymeric ligands for quantum dot (QD) water solubilization to yield biocompatible and derivatizable QDs with compact size (~10-12 nm diameter), high quantum yields (>50%), excellent stability across a large pH range (pH 5-10.5), and low nonspecific binding. To address the fundamental problem of thiol instability in traditional ligand exchange systems, the polymers here employ a stable multidentate imidazole binding motif to the QD surface. The polymers are synthesized via reversible addition-fragmentation chain transfer (RAFT)-mediated polymerization to produce molecular weight controlled monodisperse random copolymers from three types of monomers that feature imidazole groups for QD binding, polyethylene glycol (PEG) groups for water solubilization, and either primary amines or biotin groups for derivatization. The polymer architecture can be tuned by the monomer ratios to yield aqueous QDs with targeted surface functionalities. By incorporating amino-PEG monomers, we demonstrate covalent conjugation of a dye to form a highly efficient QD-dye energy transfer pair as well as covalent conjugation to streptavidin for high-affinity single molecule imaging of biotinylated receptors on live cells with minimal non-specific binding. The small size and low serum binding of these polymer-coated QDs also allow us to demonstrate their utility for in-vivo imaging of the tumor microenvironment in live mice. PMID:20025223

  10. Synthesis, Crystal structure, and Hirshfeld Surface Analysis of a New Mixed Ligand Copper(II) Complex.

    PubMed

    Shit, Shyamapada; Marschner, Christoph; Mitra, Samiran

    2016-01-01

    A new mixed ligand copper(II) complex, [Cu(2,4-pydc)(pic)(H(2)O)]∙H(2)O (1) (where 2,4-pydc = pyridine-2,4-dicarboxylate, pic = 2-picolylamine) has been synthesized and characterized by elemental analysis, FT-IR and UV-Vis spectroscopic and thermogravimetric methods. Single crystal X-ray diffraction analysis reveals that copper(II) atom in the title complex adopts distorted square pyramidal geometry. Structural characterization also reveals that interplay of O-H···O, N-H···O, C-H···O, and C-H···π interactions between lattice and coordinated water and ligands significantly contribute to the crystal packing leading to the formation and strengthening of three dimensional supramolecular assembly. Hirshfeld surface analysis employing 3D molecular surface contours and 2D fingerprint plots have been used to analyze intermolecular interactions present in the solid state of the crystal. PMID:26970797

  11. Synthesis, spectral characterization, molecular modeling and antimicrobial activity of new potentially N2O2 Schiff base complexes

    NASA Astrophysics Data System (ADS)

    Adly, Omima M. I.; Taha, Ali; Fahmy, Shery A.

    2013-12-01

    Metal complexes of a new potentially tetradentate symmetrical Schiff base ligand (H2L) with Cu(II), Ni(II), Co(II), VO(IV), Zn(II), Cd(II), Ce(III), Fe(III) and UO2(VI) metal ions have been synthesized and characterized based on their elemental analyses, spectral (IR, UV-Vis, 1H NMR and mass spectra), magnetic and molar conductance studies as well as thermal gravimetric analysis (TGA). The synthesized complexes have the general formula [MHxL(H2O)yXn]: x = 0-1, y = 0-4 and n = 0-1; where: L = dianion of 6-hydroxy-5-[N-(2-{[(1E)-1-(6-hydroxy-2,4-dioxo-3,4-dihydro-2H-1,3-thiazin-5-yl)ethylidene]amino}ethyl) ethanimidoyl]-2H-1,3-thiazine-2,4(3H)-dione and X = nitrate or sulphate anion. The ligand behaves as diabasic tetradentate N2O2 sites, except in cases of Co(II), VO(IV) and UO2(VI) metal ions, it behaves as monobasic tetradentate Schiff base ligand. The metal complexes exhibited square planar, square-pyramidal and octahedral geometrical arrangements except for Ce(III) and UO2(VI) complexes, they are octa-coordinated. The Coats-Redfern equation was used to calculate the kinetic and thermodynamic parameters for the different thermal decomposition stages of some complexes. Structural parameters of the ligand and its metal complexes have been theoretically computed on the basis of semiemperical PM3 level, and the results were correlated with their experimental data. The antimicrobial activities of the ligand and its metal complexes were tested against some Gram-positive and Gram-negative bacteria; and fungus strain and the results were discussed.

  12. Total Synthesis of Verruculogen and Fumitremorgin A Enabled by Ligand-Controlled C-H Borylation.

    PubMed

    Feng, Yu; Holte, Dane; Zoller, Jochen; Umemiya, Shigenobu; Simke, Leah R; Baran, Phil S

    2015-08-19

    Verruculogen and fumitremorgin A are bioactive alkaloids that contain a unique eight-membered endoperoxide. Although related natural products such as fumitremorgins B and C have been previously synthesized, we report the first synthesis of the more complex, endoperoxide-containing members of this family. A concise route to verruculogen and fumitremorgin A relied not only on a hydroperoxide/indole hemiaminal cyclization, but also on the ability to access the seemingly simple starting material, 6-methoxytryptophan. An iridium-catalyzed C-H borylation/Chan-Lam procedure guided by an N-TIPS group enabled the conversion of a tryptophan derivative into a 6-methoxytryptophan derivative, proving to be a general way to functionalize the C6 position of an N,C3-disubstituted indole for the synthesis of indole-containing natural products and pharmaceuticals. PMID:26256033

  13. Synthesis, Characterization, Antimicrobial, DNA Cleavage, and In Vitro Cytotoxic Studies of Some Metal Complexes of Schiff Base Ligand Derived from Thiazole and Quinoline Moiety

    PubMed Central

    Yernale, Nagesh Gunvanthrao; Bennikallu Hire Mathada, Mruthyunjayaswamy

    2014-01-01

    A novel Schiff base ligand N-(4-phenylthiazol-2yl)-2-((2-thiaxo-1,2-dihydroquinolin-3-yl)methylene)hydrazinecarboxamide (L) obtained by the condensation of N-(4-phenylthiazol-2-yl)hydrazinecarboxamide with 2-thioxo-1,2-dihydroquinoline-3-carbaldehyde and its newly synthesized Cu(II), Co(II), Ni(II), and Zn(II) complexes have been characterized by elemental analysis and various spectral studies like FT-IR, 1H NMR, ESI mass, UV-Visible, ESR, TGA/DTA, and powder X-ray diffraction studies. The Schiff base ligand (L) behaves as tridentate ONS donor and forms the complexes of type [ML(Cl)2] with square pyramidal geometry. The Schiff base ligand (L) and its metal complexes have been screened in vitro for their antibacterial and antifungal activities by minimum inhibitory concentration (MIC) method. The DNA cleavage activity of ligand and its metal complexes were studied using plasmid DNA pBR322 as a target molecule by gel electrophoresis method. The brine shrimp bioassay was also carried out to study the in vitro cytotoxicity properties for the ligand and its metal complexes against Artemia salina. The results showed that the biological activities of the ligand were found to be increased on complexation. PMID:24729778

  14. Phenoxy-bridged binuclear Zn(II) complex holding salen ligand: Synthesis and structural characterization

    NASA Astrophysics Data System (ADS)

    Azam, Mohammad; Al-Resayes, Saud I.

    2016-03-01

    A novel binuclear phenoxo-bridged zinc complex obtained from the interaction of ligand, 2,2-(1E,1E)-(2,2-dimethylpropane-1,3-diyl)bis(azanylylidene) bis(methanylylidene)diphenol with zinc chloride is reported. The synthesized and isolated zinc complex has been characterized by FT-IR, 1H- and 13C- NMR, ESI-MS, TGA/DTA and single crystal X-ray diffraction studies. The phenoxo-bridge in this binuclear Zn(II) complex is due to the phenolic oxygen of the salen liagnd. The complex crystallizes in monoclinic P-1 space group, and different geometry has been assigned for both zinc ions in the complex.

  15. Synthesis of new ligands for targeting the S1P1 receptor.

    PubMed

    Schilson, Stefanie S; Keul, Petra; Shaikh, Rizwan S; Schäfers, Michael; Levkau, Bodo; Haufe, Günter

    2015-03-01

    Sphingosine-1-phosphate (S1P) influences various fundamental biological processes by interacting with a family of five G protein-coupled receptors (S1P1-5). FTY720, a sphingosine analogue, which was approved for treatment of relapsing forms of multiple sclerosis, is phosphorylated in vivo and acts as an agonist of four of the five S1P receptor subtypes. Starting from these lead structures we developed new agonists for the S1P1 receptor. The biological activity was tested in vivo and promising ligands were fluorinated at different positions to identify candidates for positron emission tomography (PET) imaging after [(18)F]-labelling. The radioligands shall enable the imaging of S1P1 receptor expression in vivo and thus may serve as novel imaging markers of S1P-related diseases. PMID:25656338

  16. Synthesis and characterization of titanium complex with a dithiolate ligand for green LCD color filter dyes

    PubMed Central

    2012-01-01

    Three green compounds for color filter dyes based on bis(cyclopentadienyl) titanium complexes including dithiolate ligand were synthesized. Physical properties by the change of the substitution groups of the synthesized materials were systematically examined. UV-visible absorption spectrum of the synthesized materials showed maximum absorbing wavelengths of 427 to 430 nm and 632 to 635 nm in solution state, and 434 to 438 nm and 637 to 651 nm in film state, indicating green and black colors. It was observed that the extinction coefficient values (log ε) of all the synthesized materials are very high at 4.0 or above. In addition, it was shown that since the Td values of three synthesized materials show thermal stability higher than 240°C, they possess high potential to be applied as dyes for LCD color filter and black matrix addictive. PMID:23171599

  17. Synthesis and characterization of two polyoxometalates consisting of different Cu-ligand hydrogen phosphate units

    SciTech Connect

    Yan, Jinshuang; Zhao, Xiaofang; Huang, Jiao; Gong, Kaining; Han, Zhangang Zhai, Xueliang

    2014-03-15

    Two polyoxometalates [(Cu-mbpy){sub 4}(HPO{sub 4}){sub 2}(H{sub 2}O){sub 2}][PMo{sub 12}O{sub 40}]·H{sub 2}O (1) and [(Cu-mbpy){sub 6}(HPO{sub 4}){sub 4}][PW{sub 12}O{sub 40}]·4H{sub 2}O (2) (mbpy=4,4'-dimethyl-2,2'-dipyridyl in 1; 5,5″-dimethyl-2,2'-dipyridyl in 2) have been synthesized and characterized by IR, X-ray powder diffraction, TG analysis and electrochemical property. The structural features of 1–2 are in their cationic moieties consisting of different linkages of [Cu-mbpy]{sup 2+} and HPO{sub 4}{sup 2−} groups. In 1 four Cu-mbpy bridged by two HPO{sub 4}{sup 2−} ions form a discrete cluster with an interesting octahedron of (Cu{sub 4}P{sub 2}), while in 2 Cu-mbpy fragments are bridged by HPO{sub 4}{sup 2−} ions into 1D structure consisting of trigonal bipyramidal polyhedra of (Cu{sub 3}P{sub 2}). Photocatalytic experiments indicate that compounds 1 and 2 are actively photocatalytic for degradation of methyl orange in the presence of H{sub 2}O{sub 2} under UV light irradiation. -- Graphical abstract: Two polyoxometalate-based supramolecular compounds consisting of different linkages based on Cu-ligand and HPO{sub 4}{sup 2−} groups have been synthesized and characterized. The photocatalytic activity are studied. Highlights: • Two polyoxometalate-based supramolecular compounds consisting of different linkages based on Cu-ligand and HPO{sub 4}{sup 2−} groups have been synthesized. • Hydrogen bonding and π…π interactions play important roles in constructing crystal supramolecular frameworks. • Two compounds represent a high photocatalytic activity in the degradation of methyl orange.

  18. Synthesis, X-ray crystal structures and catecholase activity investigation of new chalcone ligands

    NASA Astrophysics Data System (ADS)

    Thabti, Salima; Djedouani, Amel; Rahmouni, Samra; Touzani, Rachid; Bendaas, Abderrahmen; Mousser, Hénia; Mousser, Abdelhamid

    2015-12-01

    The reaction of dehydroacetic acid DHA carboxaldehyde and RCHO derivatives (R = quinoleine-8-; indole-3-; pyrrol-2- and 4-(dimethylamino)phenyl - afforded four new chalcone ligands (4-hydroxy-6-methyl-3-[(2E)-3-quinolin-8-ylprop-2-enoyl]-2H-pyran-2-one) L1, (4-hydroxy-3-[(2E)-3-(1H-indol-3-yl)prop-2-enoyl]-6-methyl-2H-pyran-2-one) L2, (4-hydroxy-6-methyl-3-[(2E)-3-(1H-pyrrol-2-yl)prop-2-enoyl]-2H-pyran-2-one) L3, and (3-{(2E)-3-[4-(dimethylamino)phenyl]prop-2-enoyl}-4-hydroxy-6-methyl-2H-pyran-2-one) L4. L3 and L4 were characterized by X-ray crystallography. Molecules crystallize with four and two molecules in the asymmetric unit, respectively and adopt an E conformation about the Cdbnd C bond. Both structures are stabilized by an extended network O-H … O. Furthermore, N-H … O and C-H … O hydrogen bonds are observed in L3 and L4 structures, respectively. The in situ generated copper (II) complexes of the four compounds L1, L2, L3 and L4 were examined for their catalytic activities and were found to catalyze the oxidation reaction of catechol to o-quinone under atmospheric dioxygen. The rates of this oxidation depend on three parameters: ligand, ion salts and solvent nature and the combination L2[Cu (CH3COO)2] leads to the faster catalytic process.

  19. Synthesis, electrochemical and photophysical properties of heterodinuclear Ru-Mn and Ru-Zn complexes bearing ambident Schiff base ligand.

    PubMed

    Guillo, Pascal; Hamelin, Olivier; Loiseau, Frédérique; Pécaut, Jacques; Ménage, Stéphane

    2010-06-28

    While ruthenium tris(diimine) complexes have been extensively studied, this is not the case with ruthenium bis(diimine)X(2) complexes where X represents a pyridinyl-based ligand. The synthesis of a new complex ([2][PF(6)](2)) bearing two ambident Schiff base ligands (HL) constituted by the assembly of phenol and pyridinyl moieties is reported. Thanks to the heteroditopic property of HL, compound [2](2+) was used as an original metalloligand for the coordination of a redox-active (Mn(III)) and redox-inactive (Zn(II)) second metal cation affording three heterodinuclear complexes, namely, [(bpy)(2)Ru(2)Mn(acac)][PF(6)](2) ([3][PF(6)](2); acac = acetylacetonate), [(bpy)(2)Ru(2)Mn(OAc)][PF(6)](2) ([4][PF(6)](2), OAc = acetate), and [(bpy)(2)Ru(2)Zn][PF(6)](2) ([5][PF(6)](2)). The influence of the second metal with regard to the photophysical and electrochemical properties of the ruthenium bis(diimine)X(2) subunit was then investigated. In the case of Ru(II)-Mn(III) heterodinuclear complexes, a partial quenching of the luminescence was observed as a consequence of an efficient electron transfer process from the ruthenium to the manganese. EPR and spectrophotometric analyses of the oxidized species resulting from the one-electron oxidation of compounds [3](2+) and [4](2+) showed the formation of a Mn(IV) species for [3](2+) and an organic free radical for [4](2+). PMID:20485756

  20. Accessibility control on copper(II) complexes in mesostructured porous silica obtained by direct synthesis using bidentate organosilane ligands.

    PubMed

    Zhou, Wen-Juan; Albela, Belén; Perriat, Pascal; He, Ming-Yuan; Bonneviot, Laurent

    2010-08-17

    The accessibility of metal(II) complexes in 2D hexagonal mesostructured porous silicas obtained by direct synthesis is controlled using an appropriate organosilane ligand. This is exemplified here using copper(II) as a transition metal probe and a neutral or negatively charged ligand: N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, L(A), and, N-salicylaldimine-propylamine-trimethoxysilane, L(B)(-), respectively. L(A) leads to inaccessible complexes located into the pore wall and called "embedded" sites here where silanolate groups from the siliceous network block the access to Cu(II) ions. By contrast, L(B)(-) generates accessible complexes, named "showing-on" sites here. The copper-containing silicas were synthesized with various metal molar ratios (M/SiO(2) = 0.5-3%) in basic media, with cetyltrimethylammonium p-toluenesulfonate (CTATos) as template and with sodium silicate solution as silicon source. A soft template extraction procedure has been developed to preserve the complex integrity of the showing-on copper sites during the treatment. The embedded copper(II) and nickel(II) sites were compared. Materials containing embedded, showing-on, and grafted sites were also compared with regard to pore size, surface polarity, and metal leaching. The material containing showing-on sites was found to be catalytically active for the hydroxylation of phenol into catechol and hydroquinone. Both textural and structural properties of the material and the copper sites were investigated using XRD, TEM, N(2) sorption isotherms, TGA, FT-IR, UV-visible, and EPR spectroscopies. PMID:20695596

  1. Spectral, magnetic, biocidal screening, DNA binding and photocleavage studies of mononuclear Cu(II) and Zn(II) metal complexes of tricoordinate heterocyclic Schiff base ligands of pyrazolone and semicarbazide/thiosemicarbazide based derivatives

    NASA Astrophysics Data System (ADS)

    Raman, N.; Selvan, A.; Manisankar, P.

    2010-07-01

    We depict the synthesis and characterization of copper(II) and zinc(II) coordination compounds of 4-(3',4'-dimethoxybenzaldehydene)2-3-dimethyl-1-phenyl-3-pyrazolin-5-semicarbazone ( 1a), 4-(3',4'-dimethoxybenzaldehydene)2-3-dimethyl-1-phenyl-3-pyrazolin-5-thiosemicarbazone ( 1b), 4-(3'-hydroxy-4'-nitrobenzaldehydene)2-3-dimeth yl-1-phenyl-3-pyrazolin-5-semicarbazone ( 1c) and 4-(3'-hydroxy-4'-nitrobenzal dehydene)2-3-dimethyl-1-phenyl-3-pyrazolin-5-thiosemicarbazone ( 1d). All the remote compounds have the general composition [ML 2] (M = Cu(II) and Zn(II)); L = Schiff base ( 1a- 1d). All the complexes were characterized by elemental analysis, molar conductivity, IR, 1H NMR, UV-vis, ESI-Mass, magnetic susceptibility measurements, cyclic voltammetric measurements, and EPR spectral studies. It has been originated that the Schiff bases with Cu(II) and Zn(II) ions form mononuclear complexes on 1:2 (metal:ligand) stoichiometry. Distorted octahedral environment is suggested for the metal complexes. The conductivity data confirm the non-electrolytic nature of the complexes. The interaction of CuL 21a- 1d complexes with CT DNA was investigated by spectroscopic, electrochemical and viscosity measurements. Results suggest that the copper complexes bind to DNA via an intercalative mode. Moreover, the complexes have been found to promote the photocleavage of plasmid DNA pBR322 under irradiation at 365 nm. The Schiff bases and their metal complexes were screened for their antifungal and antibacterial activities against different species of pathogenic fungi and bacteria and their biopotency has been discussed.

  2. Synthesis and preliminary evaluation of (S)-[11C]-exaprolol, a novel beta-adrenoceptor ligand for PET.

    PubMed

    van Waarde, Aren; Doorduin, Janine; de Jong, Johan R; Dierckx, Rudi A; Elsinga, Philip H

    2008-01-01

    Positron-emitting beta-adrenoceptor ligands for the CNS could allow determination of changes in beta-adrenoceptor availability after treatment of patients with norepinephrine reuptake inhibitors or tricyclic antidepressants, and differential diagnosis between multiple sclerosis and other brain disorders in an early stage of the disease. No ligands suitable for this purpose are available for human use. In order to prepare a tracer for human studies, we labeled the biologically active enantiomer of the beta-blocker exaprolol with (11)C. Exaprolol has the appropriate lipophilicity (log P + 1.6) for entry of the CNS and is claimed to be a very potent beta-adrenoceptor antagonist. (S)-Desisopropyl-exaprolol was synthesized by reaction of 2-hexylphenol with (S)-glycidyl-nosylate followed by ring opening using ammonia gas. The desisopropyl precursor was reacted with (11)C-acetone in methanol to produce (S)-[(11)C]-exaprolol. Radiochemical purification was performed with RP-HPLC and was followed by Sep-Pak formulation. The labeled product was i.v. injected into male Wistar rats. Brain images were acquired using a microPET Focus 220 and the biodistribution of (11)C was assessed. The radiochemical yield of (S)-[(11)C]-exaprolol was 7% with a total synthesis time of 30 min. Specific activities were >10 GBq/micromol. Brain uptake of the tracer reached a maximum after 15 min. Standardized uptake values were moderate (0.5-0.9) but sufficient for imaging. However, beta-blockade (propranolol, 2.5mg/kg body weight) did not lower tracer uptake in any CNS region and washout from the brain was not accelerated when propranolol was administered 40 min after injection of (S)-[(11)C]-exaprolol. Tracer binding in lung, spleen and erythrocytes was lowered after beta-blockade, but the myocardial uptake of radioactivity was not affected. These data indicate that (S)-[(11)C]-exaprolol is not a suitable beta-adrenoceptor ligand for PET, probably because the in vivo affinity of exaprolol to beta

  3. Synthesis, structure, DFT calculations, electrochemistry, fluorescence, DNA binding and molecular docking aspects of a novel oxime based ligand and its palladium(II) complex.

    PubMed

    Bandyopadhyay, Nirmalya; Pradhan, Ankur Bikash; Das, Suman; Lu, Liping; Zhu, Miaoli; Chowdhury, Shubhamoy; Naskar, Jnan Prakash

    2016-07-01

    A novel oxime based ligand, phenyl-(pyridine-2-yl-hydrazono)-acetaldehyde oxime (LH), and its palladium(II) complex (1) have been synthesised and spectroscopically characterised. The ligand crystallizes in the monoclinic space group (P21/c). The X-ray crystal structure of the ligand shows that it forms a hydrogen bonded helical network. The ligand has been characterised by C, H and N microanalyses, (1)H and (13)C NMR, ESI-MS, FT-IR and UV-Vis spectral measurements. Geometry optimizations at the level of DFT show that the Pd(II) centre is nested in a square-planar 'N3Cl' coordination chromophore. The diamagnetic palladium complex has been characterised by C, H and N microanalyses, FAB-MS, FT-IR, UV-Vis spectra and molar electrical conductivity measurements. The observed electronic spectrum of 1 correlates with our theoretical findings as evaluated through TD-DFT. 1 displays quasi-reversible Pd(II)/Pd(III) and Pd(III)/Pd(IV) redox couples in its CV in acetonitrile. 1 is nine-fold more emissive with respect to the binding ligand. Biophysical studies have been carried out to show the DNA binding aspects of both the ligand and complex. The binding constants for the ligand and complex were found to be 3.93×10(4) and 1.38×10(3)M(-1) respectively. To have an insight into the mode of binding of LH and 1 with CT DNA a hydrodynamic study was also undertaken. The mode of binding has also been substantiated through molecular docking. A promising groove binding efficacy has been revealed for the ligand. PMID:27179300

  4. Synthetic aspects, spectral, thermal studies and antimicrobial screening on bis(N,N-dimethyldithiocarbamato-S,S‧)antimony(III) complexes with oxo or thio donor ligands

    NASA Astrophysics Data System (ADS)

    Chauhan, H. P. S.; Carpenter, Jaswant; Joshi, Sapana

    2014-09-01

    The bis(N,N-dimethyldithiocarbamato-S,S‧)antimony(III) complexes have been obtained by the reaction of chloro bis(N,N-dimethyldithiocarbamato-S,S‧)antimony(III) with corresponding oxo or thio donor ligands such as sodium benzoate 1, sodium thioglycolate 2, phenol 3, sodium 1-propanethiolate 4, potassium thioacetate 5, sodium salicylate 6, ethane-1,2-dithiolate 7 and disodium oxalate 8. These complexes have been characterized by the physicochemical [melting point, molecular weight determination and elemental analysis (C, H, N, S and Sb)], spectral [UV-Visible, FT-IR, far IR, NMR (1H and 13C)], thermogravimetric (TG & DTA) analysis, ESI-Mass and powder X-ray diffraction studies. Thermogravimetric analysis of the complexes confirmed the final decomposition product as highly pure antimony sulfide (Sb2S3) and powder X-ray diffraction studies show that the complexes are in lower symmetry with monoclinic crystal lattice and nano-ranged particle size (11.51-20.82 nm). The complexes have also been screened against some bacterial and fungal strains for their antibacterial and antifungal activities and compared with standard drugs. These show that the complexes have greater activities against some human pathogenic bacteria and fungi than the activities of standard drugs.

  5. Synthesis and spectral feature of benzophenone-substituted thiosemicarbazones and their Ni(II) and Cu(II) complexes

    NASA Astrophysics Data System (ADS)

    El-Asmy, A. A.; Al-Hazmi, G. A. A.

    2009-01-01

    The ligational behavior of 2-hydroxybenzophenone and 2-hydroxy-4-methoxybenzophenone N-substituted thiosemicarbazones towards Ni(II) and Cu(II) ions has been investigated. The isolated complexes were identified by elemental analyses, molar conductance, magnetic moment, IR, UV-vis and ESR spectral studies. The IR spectra indicated that the investigated thiosemicarbazones lost the N 2 proton or the N 2 and OH protons and act as mononegative or binegative tridentate ligands. The ligands containing methoxy group facilitate the deprotonation of OH by resonance more than the SH. Most of the Ni(II) complexes measured subnormal magnetic moments due to square-planar + tetrahedral configuration and supported by the electronic spectra. The percentage of square-planar to tetrahedral was calculated and found in agreement with the ligand splitting energy (10Dq). Also, Cu(II) complexes measured subnormal values due to the interaction between copper centers; the lower the value the higher the interaction. It was found that the substitutent has a noticeable effect on the distortion of the complex. The ESR spectra of some solid Cu(II) complexes at room temperature exhibit g|| > g⊥ > 2.0023 confirming a square-planar structure.

  6. Mixed ligand ruthenium(III) complexes of benzaldehyde 4-methyl-3-thiosemicarbazones with triphenylphosphine/triphenylarsine co-ligands: Synthesis, DNA binding, DNA cleavage, antioxidative and cytotoxic activity

    NASA Astrophysics Data System (ADS)

    Sampath, K.; Sathiyaraj, S.; Raja, G.; Jayabalakrishnan, C.

    2013-08-01

    The new ruthenium(III) complexes with 4-methyl-3-thiosemicarbazone ligands, (E)-2-(2-chlorobenzylidene)-N-methylhydrazinecarbothioamide (HL1) and (E)-2-(2-nitrobenzylidene)-N-methylhydrazinecarbothioamide (HL2), were prepared and characterized by various physico-chemical and spectroscopic methods. The title compounds act as bidentate, monobasic chelating ligands with S and N as the donor sites and are preferably found in the thiol form in all the complexes studied. The molecular structure of HL1 and HL2 were determined by single crystal X-ray diffraction method. DNA binding of the ligands and complexes were investigated by absorption spectroscopy and IR spectroscopy. It reveals that the compounds bind to nitrogenous bases of DNA via intercalation. The oxidative cleavage of the complexes with CT-DNA inferred that the effects of cleavage are dose dependent. Antioxidant study of the ligands and complexes showed the significant antioxidant activity against DPPH radical. In addition, the in vitro cytotoxicity of the ligands and complexes against MCF-7 cell line was assayed which showed higher cytotoxic activity with the lower IC50 values indicating their efficiency in killing the cancer cells even at low concentrations.

  7. Synthesis, Spectroscopy, and Electrochemistry of (α-Diimine)M(CO)3Br, M = Mn, Re, Complexes: Ligands Isoelectronic to Bipyridyl Show Differences in CO2 Reduction

    PubMed Central

    Vollmer, Matthew V.; Machan, Charles W.; Clark, Melissa L.; Antholine, William E.; Agarwal, Jay; Schaefer, Henry F.; Kubiak, Clifford P.; Walensky, Justin R.

    2015-01-01

    The synthesis and characterization of new Mn(I)- and Re(I)-centered organometallic complexes fashioned with 1,4-diazabutadiene (DAB) ligands is reported. Ten compounds of the type fac-(α-diimine)M(CO)3Br (M = Mn, Re) were obtained in moderate to excellent yield (35–80%) and high purity from the coordination of the five ligands with M(CO)5Br in refluxing ethanol. Despite the electronic similarity of DAB to 2,2′-bipyridyl, the complexes described herein were poor mediators of electrochemical CO2 conversion to CO, but provide insight into the role of redox-active ligands in catalysis. Additional characterization of the one-electron reduced rhenium compounds, relevant intermediates in CO2 reduction, by EPR and single-crystal X-ray analysis is described. PMID:25892841

  8. In situ ligand synthesis with the UO{sub 2}{sup 2+} cation under hydrothermal conditions

    SciTech Connect

    Frisch, Mark; Cahill, Christopher L.

    2007-09-15

    A novel uranium (VI) coordination polymer, (UO{sub 2}){sub 2}(C{sub 2}O{sub 4})(C{sub 5}H{sub 6}NO{sub 3}){sub 2} (1), has been prepared under the hydrothermal reaction of uranium nitrate hexahydrate and L-pyroglutamic acid. Compound 1 (monoclinic, C2/c, a=22.541(6) A, b=5.7428(15) A, c=15.815(4) A, {beta}=119.112(4){sup o}, Z=4, R{sub 1}=0.0237, wR{sub 2}=0.0367) consists of uranium pentagonal bipyramids linked via L-pyroglutamate and oxalate anions to form an overall two-dimensional (2D) structure. With the absence of oxalic acid within the starting materials, the oxalate anions are hypothesized to form in situ whereby decarboxylation of L-pyroglutamic acid occurs followed by coupling of CO{sub 2} to form the oxalate linkages as observed in the crystal structure. Addition of copper (II) to this system appears to promote oxalate formation in that synthetic moolooite (Cu(C{sub 2}O{sub 4}).nH{sub 2}O; 0{<=}n{<=}1) and a known uranyl oxalate [(UO{sub 2}){sub 2}(C{sub 2}O{sub 4})(OH){sub 2}(H{sub 2}O){sub 2}.H{sub 2}O], co-crystallize in significant quantity. Compound 1 exhibits the characteristic uranyl emission spectrum upon either direct uranyl excitation or ligand excitation, the latter of which shows an increase in relative intensity. This subsequent increase in the intensity indicates an energy transfer from the ligand to the uranyl cations thus illustrating an example of the antenna effect in the solid state. - Graphical abstract: A novel homometallic coordination polymer (UO{sub 2}){sub 2}(C{sub 2}O{sub 4})(C{sub 5}H{sub 6}NO{sub 3}){sub 2}, in the uranium-L-pyroglutamic acid system has been synthesized under hydrothermal conditions. The title compound consists of uranium pentagonal bipyramids bridged through both L-pyroglutamate and oxalate linkages to produce a 3D crystal structure. The oxalate anions are theorized to result from decarboxylation of L-pyroglutamic acid followed by subsequent coupling of CO{sub 2}.

  9. Copper(I) cyanide networks: synthesis, structure, and luminescence behavior. Part 2. Piperazine ligands and hexamethylenetetramine.

    PubMed

    Lim, Mi Jung; Murray, Courtney A; Tronic, Tristan A; deKrafft, Kathryn E; Ley, Amanda N; deButts, Jordan C; Pike, Robert D; Lu, Haiyan; Patterson, Howard H

    2008-08-01

    A variety of photoluminescent, and in some cases thermochromic, metal-organic networks of CuCN were self-assembled in aqueous reactions with amine ligands: (CuCN) 2(Pip) ( 1a), (CuCN) 20(Pip) 7 ( 1b), (CuCN) 7(MePip) 2 ( 2), (CuCN) 2(Me 2Pip) ( 3a), (CuCN) 4(Me 2Pip) ( 3b), (CuCN) 7(EtPip) 2 ( 4), (CuCN) 4(Et 2Pip) ( 5), (CuCN) 3(BzPip) 2 ( 6a), (CuCN) 5(BzPip) 2 ( 6b), (CuCN) 7(BzPip) 2 ( 6c), (CuCN) 4(BzPip) ( 6d), (CuCN) 2(Bz 2Pip) ( 7), (CuCN)(Ph 2CHPip) ( 8a), (CuCN) 2(Ph 2CHPip) ( 8b), (CuCN) 3(HMTA) 2 ( 9a), (CuCN) 5(HMTA) 2 ( 9b), and (CuCN) 5(HMTA) ( 9c) (Pip = piperazine, MePip = N-methylpiperazine, Me 2Pip = N, N'-dimethylpiperazine, EtPip = N-ethylpiperazine, Et 2Pip = N, N'-diethylpiperazine, BzPip = N-benzylpiperazine, Bz 2Pip = N, N'-dibenzylpiperazine, Ph 2CHPip = N-(diphenylmethyl)piperazine, and HMTA = hexamethylenetetramine). New X-ray structures are reported for 1b, 2, 3b, 4, 5, 6a, 6d, 7, 8b, 9b, and 9c. An important structural theme is the formation of (6,3) (CuCN) 2(piperazine) sheets with or without threading of independent CuCN chains. Strong luminescence at ambient temperature is observed for all but complexes 6 and 7. All luminescent compounds show a broad emission band in the blue region at about 450 nm attributable to metal-to-ligand charge transfer behavior based on the large Stokes shift between excitation and emission maxima. 3, 8, and 9 are thermochromic due to an additional lower energy emission band, which is absent at 77 K. PMID:18597424

  10. Novel ruthenium sensitizers containing functionalized hybrid tetradentate ligands: synthesis, characterization, and INDO/S analysis.

    PubMed

    Renouard, T; Fallahpour, R-A; Nazeeruddin, Md K; Humphry-Baker, R; Gorelsky, S I; Lever, A B P; Grätzel, M

    2002-01-28

    Ruthenium sensitizers of the type trans-[Ru(L(1))(X)(2)], trans-[Ru(L(2))(X)(2)], trans-[Ru(L(3))(X)(2)], and trans-[Ru(L(4))(X)(2)] (where L(1) = 6,6'-bis(1-H-benzimidazol-2-yl)-4,4'-bis(methoxycarbonyl)-2,2'-bipyridine, L(2) = 4,4' "-bis(tert-butyl)-4',4' '-bis[p-(methoxycarbonyl)phenyl]-2,2':6',2' ':6' ',2' "-quaterpyridine, L(3) = 4',4' '-bis[3,4-(dimethoxy)phenyl]-2,2':6',2' ':6' ',2' "-quaterpyridine, and L(4) = 4',4' '-diethoxycarbonyl-2,2':6',2' ':6' ',2' "-quaterpyridine; X = Cl(-), NCS(-)) were synthesized and characterized by CV, NMR, and UV-vis absorption and emission spectroscopy. The trans-dichloro and dithiocyanate complexes show MLCT transitions in the entire visible and near-IR region. The lowest energy metal-to-ligand charge-transfer transition band of the trans-dichloro complexes is around 14 300 cm(-1) in DMF solution, and these complexes show weak and broad emission signals with onset at above 10 500 cm(-1). The absorption and emission maxima of the trans-dithiocyanate complexes are blue-shifted compared to those of its trans-dichloro analogues because of the strong pi acceptor property of the NCS(-) compared to the Cl(-). The electronic spectra of trans-[Ru(L)(X)(2)] complexes were calculated by INDO/S and compared with the experimental data. The extent of mixing between metal 4d and ligand pi orbitals is discussed. Extensive pi-back-donation is observed. The panchromatic response of these novel complexes renders them as suitable sensitizers for solar energy conversion applications based on titanium dioxide mesoporous electrodes. Preliminary results using the trans-[Ru(L(4))(NCS)(2)] complex show 75% incident photon-to-current efficiencies (IPCE), yielding 18 mA/cm(2) current density under standard AM 1.5 sunlight. PMID:11800627

  11. Synthesis, characterization and biological evaluation of novel Ru(II)-arene complexes containing intercalating ligands.

    PubMed

    Nikolić, Stefan; Rangasamy, Loganathan; Gligorijević, Nevenka; Aranđelović, Sandra; Radulović, Siniša; Gasser, Gilles; Grgurić-Šipka, Sanja

    2016-07-01

    Three new ruthenium(II)-arene complexes, namely [(η(6)-p-cymene)Ru(Me2dppz)Cl]PF6 (1), [(η(6)-benzene)Ru(Me2dppz)Cl]PF6 (2) and [(η(6)-p-cymene)Ru(aip)Cl]PF6 (3) (Me2dppz=11,12-dimethyldipyrido[3,2-a:2',3'-c]phenazine; aip=2-(9-anthryl)-1H-imidazo[4,5-f] [1,10] phenanthroline) have been synthesized and characterized using different spectroscopic techniques including elemental analysis. The complexes were found to be well soluble and stable in DMSO. The biological activity of the three complexes was tested in three different human cancer cell lines (A549, MDA-MB-231 and HeLa) and in one human non-cancerous cell line (MRC-5). Complexes 1 and 3, carrying η(6)-p-cymene as the arene ligand, were shown to be toxic in all cell lines in the low micromolar/subnanomolar range, with complex 1 being the most cytotoxic complex of the series. Flow cytometry analysis revealed that complex 1 caused concentration- and time-dependent arrest of the cell cycle in G2-M and S phases in HeLa cells. This event is followed by the accumulation of the sub-G1 DNA content after 48h, in levels higher than cisplatin and in the absence of phosphatidylserine externalization. Fluorescent microscopy and acridine orange/ethidium bromide staining revealed that complex 1 induced both apoptotic and necrotic cell morphology characteristics. Drug-accumulation and DNA-binding studies performed by inductively coupled plasma mass spectrometry in HeLa cells showed that the total ruthenium uptake increased in a time- and concentration-dependent manner, and that complex 1 accumulated more efficiently than cisplatin at equimolar concentrations. The introduction of a Me2dppz ligand into the ruthenium(II)-p-cymene scaffold was found to allow the discovery of a strongly cytotoxic complex with significantly higher cellular uptake and DNA-binding properties than cisplatin. PMID:26818702

  12. Synthesis, characterization, equilibrium study and biological activity of Cu(II), Ni(II) and Co(II) complexes of polydentate Schiff base ligand.

    PubMed

    El-Sherif, Ahmed A; Shehata, Mohamed R; Shoukry, Mohamed M; Barakat, Mohammad H

    2012-10-01

    Schiff base ligand, 1,4-bis[(2-hydroxybenzaldehyde)propyl]piperazine (BHPP), and its Cu(II), Ni(II) and Co(II) metal complexes were synthesized and characterized by elemental analysis, magnetic susceptibility, molar conductance and spectral (IR and UV-vis) studies. The ground state of BHPP ligand was investigated using the BUILDER module of MOE. Metal complexes are formed in the 1:1 (M:L) ratio as found from the elemental analysis and found to have the general formula [ML]·nH(2)O, where M=Co(II), Ni(II) and Cu(II), L=BHPP. In all the studied complexes, the (BHPP) ligand behaves as a hexadentate divalent anion with coordination involving the two azomethine nitrogen's, the two nitrogen atoms of piperazine ring and the two deprotonated phenolic OH-groups. The magnetic and spectral data indicates octahedral geometry of metal(II) complexes. The ligand and their metal chelates have been screened for their antimicrobial activities using the disc diffusion method against the selected bacteria and fungi. They were found to be more active against Gram-positive than Gram-negative bacteria. Protonation constants of (BHPP) ligand and stability constants of its Cu(2+), Co(2+) and Ni(2+) complexes were determined by potentiometric titration method in 50% DMSO-water solution at ionic strength of 0.1 M sodium nitrate. It has been observed that the protonated Schiff base ligand (BHPP) have four protonation constants. The divalent metal ions Cu(2+), Ni(2+) and Co(2+) form 1:1 complexes. PMID:22935596

  13. Synthesis, characterization, equilibrium study and biological activity of Cu(II), Ni(II) and Co(II) complexes of polydentate Schiff base ligand

    NASA Astrophysics Data System (ADS)

    El-Sherif, Ahmed A.; Shehata, Mohamed R.; Shoukry, Mohamed M.; Barakat, Mohammad H.

    2012-10-01

    Schiff base ligand, 1,4-bis[(2-hydroxybenzaldehyde)propyl]piperazine (BHPP), and its Cu(II), Ni(II) and Co(II) metal complexes were synthesized and characterized by elemental analysis, magnetic susceptibility, molar conductance and spectral (IR and UV-vis) studies. The ground state of BHPP ligand was investigated using the BUILDER module of MOE. Metal complexes are formed in the 1:1 (M:L) ratio as found from the elemental analysis and found to have the general formula [ML]·nH2O, where M = Co(II), Ni(II) and Cu(II), L = BHPP. In all the studied complexes, the (BHPP) ligand behaves as a hexadentate divalent anion with coordination involving the two azomethine nitrogen's, the two nitrogen atoms of piperazine ring and the two deprotonated phenolic OH-groups. The magnetic and spectral data indicates octahedral geometry of metal(II) complexes. The ligand and their metal chelates have been screened for their antimicrobial activities using the disc diffusion method against the selected bacteria and fungi. They were found to be more active against Gram-positive than Gram-negative bacteria. Protonation constants of (BHPP) ligand and stability constants of its Cu2+, Co2+ and Ni2+ complexes were determined by potentiometric titration method in 50% DMSO-water solution at ionic strength of 0.1 M sodium nitrate. It has been observed that the protonated Schiff base ligand (BHPP) have four protonation constants. The divalent metal ions Cu2+, Ni2+ and Co2+ form 1:1 complexes.

  14. Cu(II), Ni(II), and Zn(II) Complexes of Salan-Type Ligand Containing Ester Groups: Synthesis, Characterization, Electrochemical Properties, and In Vitro Biological Activities

    PubMed Central

    Jeslin Kanaga Inba, P.; Annaraj, B.; Thalamuthu, S.; Neelakantan, M. A.

    2013-01-01

    A salen ligand on reduction and N-alkylation affords a novel [N2O2] chelating ligand containing ester groups [L = diethyl-2,2′-(propane-1,3-diylbis((2-hydroxy-3-methoxy benzyl)azanediyl))diacetate]. The purity of the ligand was confirmed by NMR and HPLC chromatograms. Its Cu(II), Ni(II), and Zn(II) complexes were synthesized and characterized by a combination of elemental analysis, IR, NMR, UV-Vis, and mass spectral data, and thermogravimetric analysis (TG/DTA). The magnetic moments, UV-Vis, and EPR spectral studies support square planar geometry around the Cu(II) and Ni(II) ions. A tetrahedral geometry is observed in four-coordinate zinc with bulky N-alkylated salan ligand. The redox properties of the copper complex were examined in DMSO by cyclic voltammetry. The voltammograms show quasireversible process. The interaction of metal complexes with CT DNA was investigated by UV-Vis absorption titration, ethidium bromide displacement assay, cyclic voltammetry methods, and agarose gel electrophoresis. The apparent binding constant values suggest moderate intercalative binding modes between the complexes and DNA. The in vitro antioxidant and antimicrobial potentials of the synthesized compounds were also determined. PMID:23983672

  15. Bio-sensitive activities of coordination compounds containing 1,10-phenanthroline as co-ligand: Synthesis, structural elucidation and DNA binding properties of metal(II) complexes

    NASA Astrophysics Data System (ADS)

    Raman, Natarajan; Mahalakshmi, Rajkumar; Mitu, Liviu

    2014-10-01

    Present work reports the DNA binding and cleavage characteristics of a series of mixed-ligand complexes having the composition [M(L)(phen)2]Cl2 (where M = Cu(II), Ni(II), Co(II) and Zn(II) and phen as co-ligand) in detail. Their structural features and other properties have been deduced from their elemental analyses, magnetic susceptibility and molar conductivity as well as from IR, UV-Vis, 1H NMR and EPR spectral studies. The UV-Vis, magnetic susceptibility and EPR spectral data of metal complexes suggest an octahedral geometry. The binding properties of these complexes with calf thymus DNA (CT-DNA) have been explored using electronic absorption spectroscopy, viscosity measurement, cyclic voltammetry and differential pulse voltammetry. The DNA-binding constants for Cu(II), Ni(II), Co(II), and Zn(II) complexes are 6.14 × 105 M-1, 1.8 × 105 M-1, 6.7 × 104 M-1 and 2.5 × 104 M-1 respectively. Detailed analysis reveals that these complexes interact with DNA through intercalation binding. Nuclease activity has also been investigated by gel electrophoresis. Moreover, the synthesized Schiff base and its mixed-ligand complexes have been screened for antibacterial and antifungal activities. The data reveal that the complexes exhibit higher activity than the parent ligand.

  16. Synthesis of polymers containing 3-hydroxypyridin-4-one bidentate ligands for treatment of iron overload

    PubMed Central

    Saghaie, Lotfollah; Liu, Dy; Hider, Robert C

    2015-01-01

    Iron overload is a clinical problem which can be prevented by using iron chelating agents. An alternative method of relieving iron overload is to reduce iron absorption from the intestine by administering specific iron chelating agents, which can bind iron to form nonabsorbable complexes. Based on this strategy, a series of polymeric ligands containing the chelating moiety 3-hydroxypyridin-4-ones (HPOs) were synthesized. The synthetic route involves the benzylation of hydroxyl group of (2-methyl-3-hydroxypyran-4-one (maltol) and conversion of benzylated maltol to 3-benzyloxypyridin-4-one derivatives by using three suitable primary amines (2,6-diaminohexanoic acid (lysine) and 1,6-diaminohexane and 5-aminopentanol). The resulted compounds incorporated into polymer by copolymerization with acryloyl chloride using 2, 2’-azobisisobutyronitrile (AIBN) as the initiator. Finally, the benzyl groups of polymers were removed by catalytic hydrogenation (Pd/C). In this work, three final polymers of HPO derivatives namely poly-2-propylamido-6-(3- hydroxy -1,4-dihydro-2-methy-4-oxopyrid-1-yl) hexanoic acid, 6-(3-hydroxy-1, 4-dihydro-2-methyl-4-oxopyrid-1-yl) hexyl-1-polypropylamide and 5-(3-hydroxy-1-,4-dihydro-2-methyl-4-oxopyrid-1-yl)-1-polyacrylate pentane were synthesized. Identification and structural elucidation of compounds were achieved by proton nuclear magnetic resonance (1H NMR), carbon nuclear magnetic resonance (13C NMR) and infrared (IR) spectroscopy. PMID:26600863

  17. Synthesis and spectroscopic studies of some chromium and molybdenum derivatives of bis-(acetylacetone)ethylenediimine ligand

    NASA Astrophysics Data System (ADS)

    Ramadan, Ramadan M.; Abdel-Rahman, Laila H.; Ismael, Mohamed; Youssef, Teraze A.; Ali, Saadia A.

    2013-10-01

    Interaction of [Cr(CO)6] with bis-(acetylacetone)ethylenediimine Schiff base, H2acacen, under reduced pressure resulted in the formation of [Cr(CO)3(H2acacen)] derivative. The Schiff base acted as a tridentate and coordinated the metal through the nitrogen of the azomethine groups and one hydroxyl group. Reaction of [Mo(CO)6] with H2acacen under sunlight irradiation in presence of air gave the oxo derivative [Mo2O6(H2acacen)2]. The ligand acted as a bidentate and coordinated the metal through the two imine groups. In presence of 2,2'-bipyridine (bpy), the reaction of [Mo(CO)6] with H2acacen gave [Mo2O6(bpy)(H2acacec)]. The structures of the reported complexes were proposed on the basis of spectroscopic studies. The proposed structures were also verified by theoretical calculations based on accurate DFT approximations. Moreover, the relative reactivity was estimated using chemical descriptors analysis.

  18. Synthesis of cellulose nanocrystals carrying tyrosine sulfate mimetic ligands and inhibition of alphavirus infection.

    PubMed

    Zoppe, Justin O; Ruottinen, Ville; Ruotsalainen, Janne; Rönkkö, Seppo; Johansson, Leena-Sisko; Hinkkanen, Ari; Järvinen, Kristiina; Seppälä, Jukka

    2014-04-14

    We present two facile approaches for introducing multivalent displays of tyrosine sulfate mimetic ligands on the surface of cellulose nanocrystals (CNCs) for application as viral inhibitors. We tested the efficacy of cellulose nanocrystals, prepared either from cotton fibers or Whatman filter paper, to inhibit alphavirus infectivity in Vero (B) cells. Cellulose nanocrystals were produced by sulfuric acid hydrolysis leading to nanocrystal surfaces decorated with anionic sulfate groups. When the fluorescent marker expressing Semliki Forest virus vector, VA7-EGFP, was incubated with CNCs, strong inhibition of virus infectivity was achieved, up to 100 and 88% for cotton and Whatman CNCs, respectively. When surface sulfate groups of CNCs were exchanged for tyrosine sulfate mimetic groups (i.e. phenyl sulfonates), improved viral inhibition was attained. Our observations suggest that the conjugation of target-specific functionalities to CNC surfaces provides a means to control their antiviral activity. Multivalent CNCs did not cause observable in vitro cytotoxicity to Vero (B) cells or human corneal epithelial (HCE-T) cells, even within the 100% virus-inhibitory concentrations. Based on the similar chemistry of known polyanionic inhibitors, our results suggest the potential application of CNCs as inhibitors of other viruses, such as human immunodeficiency virus (HIV) and herpes simplex viruses. PMID:24628489

  19. Synthesis, characterization and properties of copper(I) complexes with bis(diphenylphosphino)-ferrocene ancillary ligand

    NASA Astrophysics Data System (ADS)

    Liu, Xinfang; Zhang, Songlin; Ding, Yuqiang

    2012-06-01

    Three copper(I) complexes (2-4) containing dppf ancillary ligand (dppf = bis(diphenylphosphino)-ferrocene) were synthesized when chloride-bridged copper(I) complex 1 reacted with acetanilide and characterized by IR, element analysis and NMR spectrum. And the crystal structures of complexes 2 and 4 have been determined by X-ray diffraction method. Complex 2, an acetate-bridged copper(I) complex, was obtained under N2 atmosphere in un-dried solvent; the acetate ion came from the hydrolysis reaction of acetanilide due to residual water in solvent. Acetanilide was deprotonated and coordinated with the copper(I) centre to form a copper(I) amidate complex 3 when reacted in pre-dried solvent. In addition, a known complex 4, the oxidation product of dppf, was isolated from the same reaction system when reacted in air atmosphere. CV and TG experiments were carried out to check the electron transfer properties and thermal stabilities of complexes 2-3. Finally, the arylation reaction of complex 3 with iodobenzene was performed to study the reaction mechanism of copper(I) catalyzed Goldberg reaction.

  20. Synthesis and pharmacological evaluation of new biphenylic derivatives as CB2 receptor ligands.

    PubMed

    Bertini, Simone; Chicca, Andrea; Arena, Chiara; Chicca, Stefano; Saccomanni, Giuseppe; Gertsch, Jürg; Manera, Clementina; Macchia, Marco

    2016-06-30

    Targeting type-2 cannabinoid receptor (CB2) is considered a feasible strategy to develop new drugs for the treatment of diseases like neuropathic pain, chronic inflammation, neurodegenerative disorders and cancer. Such drugs are devoid of the undesired central side effects that are typically mediated by the CB1 receptor. In this work we synthesized 18 biphenylic carboxamides as new CB2-selective ligands and evaluated their pharmacological profiles. The functional activity of these compounds is strongly influenced by the nature of the substituent at position 4' and 5 of the biphenyl scaffold. Position 5 seems to be responsible for the agonist or inverse agonist behaviour independently of the substituent in position 4', with the exception of the methoxyl group which transforms both full agonists and inverse agonists into neutral antagonists. This study provides a novel complete toolbox of CB2 functional modulators that derive from the same chemical scaffold. Such probes may be useful to investigate the biological role of CB2 receptors in cellular assays. PMID:27078864

  1. Optimization of the aqueous synthesis of Cu₂S quantum dots with different surface ligands.

    PubMed

    Wang, Yue; Liu, Liwei; Wang, Qian; Hu, Siyi; Zou, Peng; Shi, Jing; Zhang, Xihe

    2016-01-01

    Surface functionalization of quantum dots (QDs) is one of the most important aspects of designing and preparing the desired QDs for intended optical and biomedical applications. In this paper, we synthesized aqueous-phase Cu2S quantum dots coating by three different stabilizers, i.e. mercaptoacetic acid, mercaptopropionic acid and glutathione (GSH). Different stabilizers can influence the coordination modes between Cu(+) on the surface of Cu2S and S(2-) of the ligand. The Cu2S QDs were characterized by UV-vis spectroscopy, energy dispersive spectrometry, transmission electron microscopy, Fourier transform infrared spectroscopy, x-ray diffraction and Raman spectra. Then, we performed a systematic study to evaluate the colloidal stability and in vitro toxicity of the formulations of Cu2S QDs with different stabilizers. Our results show that Cu2S QDs modified with different stabilizers have distinct functional groups on their surface and these groups make Cu2S produce different vibrations according to Raman spectra. The Cu2S-GSH exhibit the best colloidal stability in all pH buffer solutions and the lowest toxicity compare to the other two stabilizers. These properties make the Cu2S-GSH quantum dots a candidate for bioapplications in the future. PMID:26606519

  2. Group 10 complexes containing phosphinomethylamine ligands: Synthesis, structural analysis and electrochemical studies

    SciTech Connect

    Waggoner, Nolan W.; Spreer, Lindsay S.; Boro, Brian J.; DuBois, Daniel L.; Helm, Monte L.

    2012-01-15

    The reaction of [M(triphos)OTf](OTf) (M = Pd, Pt; triphos = (Ph2PCH2CH2)2PPh; OTf = triflate) with one equivalent of a diphenylphosphinomethylamine ligand (PPh2NPh(R), R = Ph or Me) leads to the formation of the M(II) complexes [Pd(triphos)PPh2NPh(R)](OTf)2 (1a, R = Ph; 1b, R = Me) and [Pt(triphos)PPh2NPh(R)]- (OTf)2 (2a, R = Ph; 2b, R = Me). Complexes 1a, 1b, 2a and 2b were obtained in moderate yields and characterized by elemental analysis, 1H, 13C, 31P NMR and X-ray diffraction. The redox behavior of these complexes shows a reversible reduction wave with half-wave potentials ranging from -1.04 to -1.23 V. Electrocatalytic proton reduction studies demonstrate these complexes function as hydrogen production catalysts with turn over frequencies ranging from 120 to 200 s-1. We thank Research Corporation Cottrell Science Award (7293) and Fort Lewis College for financial support of this project. Pacific Northwest National Laboratory collaborators would like to acknowledge the support of the US Department of Energy Basic Energy Sciences’ Chemical Sciences, Geosciences, and Biosciences Division. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

  3. Design, synthesis and biological evaluation of ligands selective for the melanocortin-3 receptor.

    PubMed

    Hruby, Victor J; Cai, Minying; Cain, James P; Mayorov, Alexander V; Dedek, Matthew M; Trivedi, Devendra

    2007-01-01

    The processed products of the proopiomelanocortin gene (ACTH, alpha-MSH, beta-MSH, gamma-MSH, etc.) interact with five melanocortin receptors, the MC1R, MC2R, MC3R, MC4R, and MC5R to modulate and control many important biological functions crucial for good health both peripherally (as hormones) and centrally (as neurotransmitters). Pivotal biological functions include pigmentation, adrenal function, response to stress, fear/flight, energy homeostasis, feeding behavior, sexual function and motivation, pain, immune response, and many others, and are believed to be involved in many disease states including pigmentary disorders, adrenal disorders, obesity, anorexia, prolonged and neuropathic pain, inflammatory response, etc. The melanocortin-3 receptor (MC3R) is found primarily in the brain and spinal cord and also in the periphery, and its biological functions are still not well understood. Here we review some of the biological functions attributed to the MC3R, and then examine in more detail efforts to design and synthesize ligands that are potent and selective for the MC3R, which might help resolve the many questions still remaining about its function. Though some progress has been made, there is still much to be done in this critical area. PMID:17584128

  4. Ru-Zn heteropolynuclear complexes containing a dinucleating bridging ligand: synthesis, structure, and isomerism.

    PubMed

    Mognon, Lorenzo; Benet-Buchholz, Jordi; Rahaman, S M Wahidur; Bo, Carles; Llobet, Antoni

    2014-12-01

    Mononuclear complexes in- and out-[Ru(Cl)(trpy)(Hbpp)](+) (in-0, out-0; Hbpp is 2,2'-(1H-pyrazole-3,5-diyl)dipyridine and trpy is 2,2':6',2″-terpyridine) are used as starting materials for preparation of Ru-Zn heterodinuclear out-{[Ru(Cl)(trpy)][ZnCl2](μ-bpp)} (out-2) and heterotrinuclear in,in- and out,out-{[Ru(Cl)(trpy)]2(μ-[Zn(bpp)2])}(2+) (in-3, out-3) constitutional isomers. Further substitution of the Cl ligand from the former complexes leads to Ru-aqua out,out-{[Ru(trpy)(H2O)]2(μ-[Zn(bpp)2])}(4+) (out-4) and the oxo-bridged Ru-O-Ru complex in,in-{[Ru(III)(trpy)]2(μ-[Zn(bpp)2(H2O)]μ-(O)}(4+) (in-5). All complexes are thoroughly characterized by the usual analytical techniques as well as by spectroscopy by means of UV-vis, MS, and when diamagnetic NMR. CV and DPV are used to extract electrochemical information and monocrystal X-ray diffraction to characterize complexes out-2, in-3, out-3, and in-5 in the solid state. Complex out-3 photochemically isomerizes toward in-3, as can be observed by NMR spectroscopy and rationalized by density functional theory based calculations. PMID:25393055

  5. Optimization of the aqueous synthesis of Cu2S quantum dots with different surface ligands

    NASA Astrophysics Data System (ADS)

    Wang, Yue; Liu, Liwei; Wang, Qian; Hu, Siyi; Zou, Peng; Shi, Jing; Zhang, Xihe

    2016-01-01

    Surface functionalization of quantum dots (QDs) is one of the most important aspects of designing and preparing the desired QDs for intended optical and biomedical applications. In this paper, we synthesized aqueous-phase Cu2S quantum dots coating by three different stabilizers, i.e. mercaptoacetic acid, mercaptopropionic acid and glutathione (GSH). Different stabilizers can influence the coordination modes between Cu+ on the surface of Cu2S and S2- of the ligand. The Cu2S QDs were characterized by UV-vis spectroscopy, energy dispersive spectrometry, transmission electron microscopy, Fourier transform infrared spectroscopy, x-ray diffraction and Raman spectra. Then, we performed a systematic study to evaluate the colloidal stability and in vitro toxicity of the formulations of Cu2S QDs with different stabilizers. Our results show that Cu2S QDs modified with different stabilizers have distinct functional groups on their surface and these groups make Cu2S produce different vibrations according to Raman spectra. The Cu2S-GSH exhibit the best colloidal stability in all pH buffer solutions and the lowest toxicity compare to the other two stabilizers. These properties make the Cu2S-GSH quantum dots a candidate for bioapplications in the future.

  6. Co(III) and Ni(II) Complexes Containing Bioactive Ligands: Synthesis, DNA Binding, and Photocleavage Studies

    PubMed Central

    Prabhakara, M. C.; Basavaraju, B.; Naik, H. S. Bhojya

    2007-01-01

    DNA binding and photocleavage characteristics of a series of mixed ligand complexes of the type [M(bpy)2qbdp](PF6)n·xH2O (where M = Co(III) or Ni(II), bpy = 2.2′-bipryidine, qbdp = Quinolino[3,2-b]benzodiazepine, n = 3 or 2 and x = 5 or 2) have been investigated. The DNA binding property of the complexes with calf thymus DNA has been investigated by using absorption spectra, viscosity measurements, as well as thermal denaturation studies. Intrinsic binding constant (Kb) has been estimated under similar set of experimental conditions. Absorption spectral studies indicate that the Co(III) and Ni(II) complexes intercalate between the base pairs of the CT-DNA tightly with intrinsic DNA binding constant of 1.3 × 106 and 3.1 × 105 M−1 in Tris-HCl buffer containing 50 mM NaCl, respectively. The proposed DNA binding mode supports the large enhancement in the relative viscosity of DNA on binding to quinolo[3,2-b]benzodiazepine. The oxidative as well as photo-induced cleavage reactions were monitered by gel electrophoresis for both complexes. The photocleavage experiments showed that the cobalt(III) complex can cleave pUC19 DNA effectively in the absence of external additives as an effective inorganic nuclease. PMID:17541480

  7. Synthesis, binding studies and molecular modeling of novel cannabinoid receptor ligands.

    PubMed

    Osman, Noha A; Mahmoud, Amr H; Allarà, Marco; Niess, Raimund; Abouzid, Khaled A; Di Marzo, Vincenzo; Abadi, Ashraf H

    2010-12-15

    In the present work, we report upon the design, synthesis and biological evaluation of new anandamide derivatives obtained by modifications of the fatty acyl chain and/or of the ethanolamide 'tail'. The compounds are of the general formula: 6-(substituted-phenyl)/naphthyl-4-oxohex-5-enoic acid N-substituted amide and 7-naphthyl-5-oxohept-6-enoicacid N-substituted amide. The novel compounds had been evaluated for their binding affinity to CB1/CB2 cannabinoid receptors, binding studies showed that some of the newly developed compounds have measurable affinity and selectivity for the CB2 receptor. Compounds XI and XVIII showed the highest binding affinity for CB2 receptor. None of the compounds exhibited inhibitory activity towards anandamide hydrolysis, thus arguing in favor of their enzymatic stability. The structure-activity relationship has been extensively studied through a tailor-made homological model using constrained docking in addition to pharmacophore analysis, both feature and field based. PMID:21074998

  8. Current state of laser synthesis of metal and alloy nanoparticles as ligand-free reference materials for nano-toxicological assays

    PubMed Central

    Rehbock, Christoph; Jakobi, Jurij; Gamrad, Lisa; van der Meer, Selina; Tiedemann, Daniela; Taylor, Ulrike; Kues, Wilfried; Rath, Detlef

    2014-01-01

    Summary Due to the abundance of nanomaterials in medical devices and everyday products, toxicological effects related to nanoparticles released from these materials, e.g., by mechanical wear, are a growing matter of concern. Unfortunately, appropriate nanoparticles required for systematic toxicological evaluation of these materials are still lacking. Here, the ubiquitous presence of surface ligands, remaining from chemical synthesis are a major drawback as these organic residues may cause cross-contaminations in toxicological studies. Nanoparticles synthesized by pulsed laser ablation in liquid are a promising alternative as this synthesis route provides totally ligand-free nanoparticles. The first part of this article reviews recent methods that allow the size control of laser-fabricated nanoparticles, focusing on laser post irradiation, delayed bioconjugation and in situ size quenching by low salinity electrolytes. Subsequent or parallel applications of these methods enable precise tuning of the particle diameters in a regime from 4–400 nm without utilization of any artificial surface ligands. The second paragraph of this article highlights the recent progress concerning the synthesis of composition controlled alloy nanoparticles by laser ablation in liquids. Here, binary and ternary alloy nanoparticles with totally homogeneous elemental distribution could be fabricated and the composition of these particles closely resembled bulk implant material. Finally, the model AuAg was used to systematically evaluate composition related toxicological effects of alloy nanoparticles. Here Ag+ ion release is identified as the most probable mechanism of toxicity when recent toxicological studies with gametes, mammalian cells and bacteria are considered. PMID:25247135

  9. Current state of laser synthesis of metal and alloy nanoparticles as ligand-free reference materials for nano-toxicological assays.

    PubMed

    Rehbock, Christoph; Jakobi, Jurij; Gamrad, Lisa; van der Meer, Selina; Tiedemann, Daniela; Taylor, Ulrike; Kues, Wilfried; Rath, Detlef; Barcikowski, Stephan

    2014-01-01

    Due to the abundance of nanomaterials in medical devices and everyday products, toxicological effects related to nanoparticles released from these materials, e.g., by mechanical wear, are a growing matter of concern. Unfortunately, appropriate nanoparticles required for systematic toxicological evaluation of these materials are still lacking. Here, the ubiquitous presence of surface ligands, remaining from chemical synthesis are a major drawback as these organic residues may cause cross-contaminations in toxicological studies. Nanoparticles synthesized by pulsed laser ablation in liquid are a promising alternative as this synthesis route provides totally ligand-free nanoparticles. The first part of this article reviews recent methods that allow the size control of laser-fabricated nanoparticles, focusing on laser post irradiation, delayed bioconjugation and in situ size quenching by low salinity electrolytes. Subsequent or parallel applications of these methods enable precise tuning of the particle diameters in a regime from 4-400 nm without utilization of any artificial surface ligands. The second paragraph of this article highlights the recent progress concerning the synthesis of composition controlled alloy nanoparticles by laser ablation in liquids. Here, binary and ternary alloy nanoparticles with totally homogeneous elemental distribution could be fabricated and the composition of these particles closely resembled bulk implant material. Finally, the model AuAg was used to systematically evaluate composition related toxicological effects of alloy nanoparticles. Here Ag(+) ion release is identified as the most probable mechanism of toxicity when recent toxicological studies with gametes, mammalian cells and bacteria are considered. PMID:25247135

  10. Lanthanide-directed synthesis of luminescent self-assembly supramolecular structures and mechanically bonded systems from acyclic coordinating organic ligands.

    PubMed

    Barry, Dawn E; Caffrey, David F; Gunnlaugsson, Thorfinnur

    2016-06-01

    Herein some examples of the use of lanthanide ions (f-metal ions) to direct the synthesis of luminescent self-assembly systems (architectures) will be discussed. This area of lanthanide supramolecular chemistry is fast growing, thanks to the unique physical (magnetic and luminescent) and coordination properties of the lanthanides, which are often transferred to the resulting supermolecule. The emphasis herein will be on systems that are luminescent, and hence, generated by using either visibly emitting ions (such as Eu(III), Tb(III) and Sm(III)) or near infrared emitting ions (like Nd(III), Yb(III) and Er(III)), formed through the use of templating chemistry, by employing structurally simple ligands, possessing oxygen and nitrogen coordinating moieties. As the lanthanides have high coordination requirements, their use often allows for the formation of coordination compounds and supramolecular systems such as bundles, grids, helicates and interlocked molecules that are not synthetically accessible through the use of other commonly used templating ions such as transition metal ions. Hence, the use of the rare-earth metal ions can lead to the formation of unique and stable species in both solution and in the solid state, as well as functional and responsive structures. PMID:27137947

  11. Ligand-optimized electroless synthesis of silver nanotubes and their activity in the reduction of 4-nitrophenol.

    PubMed

    Muench, Falk; Rauber, Markus; Stegmann, Christian; Lauterbach, Stefan; Kunz, Ulrike; Kleebe, Hans-Joachim; Ensinger, Wolfgang

    2011-10-14

    A facile electroless plating procedure for the controlled synthesis of nanoscale silver thin films and derived structures such as silver nanotubes was developed and the products were characterized by SEM, TEM and EDS. The highly stable plating baths consist of AgNO(3) as the metal source, a suitable ligand and tartrate as an environmentally benign reducing agent. Next to the variation of the coordinative environment of the oxidizing component, the influence of the pH value was evaluated. These two governing factors strongly affect the plating rate and the morphology of the developing silver nanoparticle films and can be used to adapt the reaction to synthetic demands. The refined electroless deposition allows the fabrication of homogeneous high aspect-ratio nanotubes in ion track etched polycarbonate. Template-embedded metal nanotubes can be interpreted as parallelled microreactors. Following this concept, both the silver nanotubes and spongy gold nanotubes obtained by the use of the silver structures as sacrificial templates were applied in the reduction of 4-nitrophenol by sodium borohydride, proving to be extraordinarily effective catalysts. PMID:21914939

  12. Ligand-optimized electroless synthesis of silver nanotubes and their activity in the reduction of 4-nitrophenol

    NASA Astrophysics Data System (ADS)

    Muench, Falk; Rauber, Markus; Stegmann, Christian; Lauterbach, Stefan; Kunz, Ulrike; Kleebe, Hans-Joachim; Ensinger, Wolfgang

    2011-10-01

    A facile electroless plating procedure for the controlled synthesis of nanoscale silver thin films and derived structures such as silver nanotubes was developed and the products were characterized by SEM, TEM and EDS. The highly stable plating baths consist of AgNO3 as the metal source, a suitable ligand and tartrate as an environmentally benign reducing agent. Next to the variation of the coordinative environment of the oxidizing component, the influence of the pH value was evaluated. These two governing factors strongly affect the plating rate and the morphology of the developing silver nanoparticle films and can be used to adapt the reaction to synthetic demands. The refined electroless deposition allows the fabrication of homogeneous high aspect-ratio nanotubes in ion track etched polycarbonate. Template-embedded metal nanotubes can be interpreted as parallelled microreactors. Following this concept, both the silver nanotubes and spongy gold nanotubes obtained by the use of the silver structures as sacrificial templates were applied in the reduction of 4-nitrophenol by sodium borohydride, proving to be extraordinarily effective catalysts.

  13. Synthesis and Application of Chiral Spiro Cp Ligands in Rhodium-Catalyzed Asymmetric Oxidative Coupling of Biaryl Compounds with Alkenes.

    PubMed

    Zheng, Jun; Cui, Wen-Jun; Zheng, Chao; You, Shu-Li

    2016-04-27

    The vastly increasing application of chiral Cp ligands in asymmetric catalysis results in growing demand for novel chiral Cp ligands. Herein, we report a new class of chiral Cp ligands based on 1,1'-spirobiindane, a privileged scaffold for chiral ligands and catalysts. The corresponding Rh complexes are shown to be excellent catalysts in asymmetric oxidative coupling reactions, providing axially chiral biaryls in 19-97% yields with up to 98:2 er. PMID:27070297

  14. The Synthesis, Structures and Chemical Properties of Macrocyclic Ligands Covalently Bonded into Layered Arrays

    SciTech Connect

    Clearfield, Abraham

    2003-10-09

    OAK-B135 The immobilization of crown ethers tends to limit the leveling effect of solvents making the macrocycles more selective. In addition immobilization has the added advantage of relative ease of recovery of the otherwise soluble crown. We have affixed CH2PO3H2 groups to azacrown ethers. The resultant phosphorylated macrocycles may spontaneously aggregate into crystalline supramolecular linear arrays or contacted with cations produce layered or linear polymers. In the linear polymers the metal and phosphonic acids covalently bond into a central stem with the macrocyclic rings protruding from the stem as leaves on a twig. Two types of layered compounds were obtained with group 4 metals. Monoaza-crown ethers form a bilayer where the M4+ plus phosphonic acid groups build the layer and the rings fill the interlayer space. 1, 10-diazadiphosphonic acids cross-link the metal phosphonate layers forming a three-dimensional array of crown ethers. In order to improve diffusion into these 3-D arrays they are spaced by inclusion of phosphate or phosphate groups. Two series of azamacrocylic crown ethers were prepared containing rings with 20 to 32 atoms. These larger rings can complex two cations per ring. Methylene phosphonic acid groups have been bonded to the aza ring atoms to increase the complexing ability of these ligands. Our approach is to carry out acid-base titrations in the absence and presence of cations to determine the pKa values of the protons, both those bonded to aza groups and those associated with the phosphonic acid groups. From the differences in the titration curves obtained with and without the cations present we obtain the stoichiometry of complex formation and the complex stability constants. Some of the applications we are targeting include phase transfer catalysis, separation of cations and the separation of radioisotopes for diagnostic and cancer therapeutic purposes.

  15. Synthesis of a series of new platinum organometallic complexes derived from bidentate Schiff-base ligands and their catalytic activity in the hydrosilylation and dehydrosilylation of styrene.

    PubMed

    Lachachi, M Belhadj; Benabdallah, Tayeb; Aguiar, Pedro M; Youcef, M Hadj; Whitwood, Adrian C; Lynam, Jason M

    2015-07-14

    The synthesis and properties of a novel class of platinum complexes containing Schiff bases as O,N-bidentate ligands is described as are the solution and solid state properties of the uncomplexed ligands. The platinum complexes were prepared from [PtBr2(COD)] (COD = 1,5-cyclooctadiene) and N-(2-hydroxy-1-naphthalidene)aniline derivatives in the presence of base (NaOBu(t)). Instead of a substitution reaction to afford cationic species, the addition of the Schiff base ligands results in both the formal loss of two equivalents of bromide and addition of hydroxide to the COD ligand of the complexes. It is proposed that this reaction proceeds through a cationic platinum complex [Pt(N-O)(COD)]Br which then undergoes addition of water and loss of HBr. An example of a dinuclear platinum complex in which two cyclo-octene ligands are bridged by an ether linkage is also reported. The platinum complexes were evaluated as catalysts for the hydrogenative and dehydrogenative silylation of styrene, the resulting behaviour is substituent, time and temperature dependent. PMID:26061657

  16. Synthesis, spectroscopic characterization, electrochemistry and biological evaluation of some binuclear transition metal complexes of bicompartmental ONO donor ligands containing benzo[b]thiophene moiety

    NASA Astrophysics Data System (ADS)

    Mahendra Raj, K.; Vivekanand, B.; Nagesh, G. Y.; Mruthyunjayaswamy, B. H. M.

    2014-02-01

    A series of new binucleating Cu(II), Co(II), Ni(II) and Zn(II) complexes of bicompartmental ligands with ONO donor were synthesized. The ligands were obtained by the condensation of 3-chloro-6-substituted benzo[b]thiophene-2-carbohydrazides and 4,6-diacetylresorcinol. The synthesized ligands and their complexes were characterized by elemental analysis and various spectroscopic techniques. Elemental analysis, IR, 1H NMR, ESI-mass, UV-Visible, TG-DTA, magnetic measurements, molar conductance and powder-XRD data has been used to elucidate their structures. The bonding sites are the oxygen atom of amide carbonyl, azomethine nitrogen and phenolic oxygen for ligands 1 and 2. The binuclear nature of the complexes was confirmed by ESR spectral data. TG-DTA studies for some complexes showed the presence of coordinated water molecules and the final product is the metal oxide. All the complexes were investigated for their electrochemical activity, only the Cu(II) complexes showed the redox property. Cu(II) complexes were square planar, whereas Co(II), Ni(II) and Zn(II) complexes were octahedral. Powder-XRD pattern have been studied in order to test the degree of crystallinity of the complexes and unit cell calculations were made. In order to evaluate the effect of antimicrobial activity of metal ions upon chelation, both the ligands and their metal complexes were screened for their antibacterial and antifungal activities by minimum inhibitory concentration (MIC) method. The results showed that the metal complexes were found to be more active than free ligands. The DNA cleaving capacities of all the complexes were analyzed by agarose gel electrophoresis method against supercoiled plasmid DNA. Among the compounds tested for antioxidant capacity, ligand 1 displayed excellent activity than its metal complexes.

  17. Synthesis, crystal structures and properties of three new mixed-ligand d{sup 10} metal complexes constructed from pyridinecarboxylate and in situ generated amino-tetrazole ligand

    SciTech Connect

    Liu Dongsheng; Huang, Xihe; Huang Changcang; Huang Gansheng; Chen Jianzhong

    2009-07-15

    Three new metal-organic frameworks, [Zn(atz)(nic)]{sub n}(1), [Zn(atz)(isonic)]{sub n}.nHisonic(2) and [Cd(atz)(isonic)]{sub n}(3) (Hnic=nicotinic acid, Hisonic=isonicotinic acid), have been firstly synthesized by employing mixed-ligand of pyridinecarboxylate with the in situ generated ligand of 5-amino-tetrazolate(atz{sup -}), and characterized by elemental analysis, IR spectroscopy, TGA and single crystal X-ray diffraction. The results revealed that 1 presents a two-dimensional (2D) 'sql' topological network constructed from the linear chain subunit of Zn(nic){sub 2} and atz{sup -} ligand. A remarkable feature of 2 is a 2-fold interpenetrated diamondoid network with free Hisonic molecules locating in the channels formed by the zigzag chain subunits of Zn(isonic){sub 2}. Complex 3 is a 3D non-interpenetrated pillared framework constructed from the double chain subunits of Cd-COO{sup -}Cd. It possesses a rarely observed (4,6)-connected 'fsc' topology. The thermal stabilities and fluorescent properties of the complexes were investigated. All of these complexes exhibited intense fluorescent emissions in the solid state at room temperature. - Graphical abstract: Three new mixed-ligand d{sup 10} metal complexes have been synthesized by employing mixed-ligand synthetic approach. Complex 1 presents a 2D 'sql' topological network. Complex 2 is a 2-fold interpenetrated diamondoid network with microporous channels. Rarely observed (4,6)-connected 'fsc' topological network was found in complex 3.

  18. Facile synthesis, spectral properties and formation mechanism of sulfur nanorods in PEG-200

    SciTech Connect

    Xie, Xin-yuan; Li, Li-yun; Zheng, Pu-sheng; Zheng, Wen-jie; Bai, Yan; Cheng, Tian-feng; Liu, Jie

    2012-11-15

    Graphical abstract: Homogeneous rod-like structure of sulfur with a typical diameter of about 80 nm and an average aspect ratio of about 6–8 was obtained. The sulfur nanoparticles could self-assemble from spherical particles to nanorods in PEG-200. During the self-assembling process, the absorption band showed a red shift which was due to the production of nanorods. Highlights: ► A novel, facile and greener method to synthesize sulfur nanorods by the solubilizing and templating effect of PEG-200 was reported. ► S{sup 0} nanoparticles could self assemble in PEG-200 and finally form monodisperse and homogeneous rod-like structure with an average diameter of about 80 nm, the length ca. 600 nm. ► The absorption band showed a red shift and the RRS intensity enhanced continuously during the self-assembling process. ► PEG-200 induced the oriented attachment of sulfur nanoparticles by the terminal hydroxyl groups. -- Abstract: The synthesis of nano-sulfur sol by dissolving sublimed sulfur in a green solvent-PEG-200 was studied. Homogeneous rod-like structure of sulfur with a typical diameter of about 80 nm and an average aspect ratio of 6–8 was obtained. The structure, morphology, size, and stability of the products were investigated by transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and dynamic light scattering (DLS) measurements. The spectral properties of the products were investigated by ultraviolet-visible (UV–vis) absorption and resonance Rayleigh scattering spectroscopy (RRS). The results showed that the spherical sulfur nanoparticles could self-assemble into nanorods in PEG-200. During the self-assembling process, the absorption band showed a red shift and the RRS intensity enhanced continuously. There was physical cross-linking between PEG and sulfur nanoparticles. PEG-200 induced the oriented attachment of sulfur nanoparticles by

  19. Synthesis, characterization and antibacterial activity of new Ln(III) complexes with an unsymmetrical schiff base ligand

    NASA Astrophysics Data System (ADS)

    Caifeng, Bi; Liangliang, Yan; Yuhua, Fan; Xia, Zhang; Aidong, Wang

    2006-07-01

    A new unsymmetrical Schiff base ligand (H2LLi) was synthesized using L-lysine, salicyladehyde and 2-hydroxy-1-naphthaldehyde. Three solid metal complexes of this ligand [Ln(H2L)(NO3)] NO3·2H2O (Ln=La, Sm, Ho) have been prepared and characterized by elemental analyses, IR spectra, UV spectra, TG-DTG and molar conductance. The antibacterial activities of the ligand and its complexes are also studied. The antibacterial experiments indicate that the ligand and its complexes possess antibacterial activity against Escherichia coli, Staphylococcus aureus and Bacillus subtilis and that the complexes have higher activity than those of the ligand.

  20. Discrete polynuclear manganese(ii) complexes with thiacalixarene ligands: synthesis, structures and photophysical properties.

    PubMed

    Suffren, Yan; O'Toole, Niall; Hauser, Andreas; Jeanneau, Erwann; Brioude, Arnaud; Desroches, Cédric

    2015-05-01

    The synthesis, crystal structure and photophysical properties of the new compound [Mn4(ThiaSO2)2F][K(18-crown-6)], ThiaSO2 = p-tert-butylsulphonylcalix[4]arene, are presented and compared to the ones of [Mn4(ThiaSO2)2F]K. The strong orange luminescence is attributed to the Mn(2+) centred (4)T1→(6)A1 transition. Its temperature and pressure dependence and quenching by molecular dioxygen are reported. The latter is attributed to energy transfer from the (4)T1 state exciting dioxygen to its (1)∑(+)g state. In the solid state, the quenching is much more efficient in [Mn4(ThiaSO2)2F][K(18-crown-6)] than in [Mn4(ThiaSO2)2F]K. This is attributed to the open pore structure of the former allowing fast diffusion of dioxygen into the crystal lattice. PMID:25825820

  1. Iron complexes of a bidentate picolyl-NHC ligand: synthesis, structure and reactivity.

    PubMed

    Liang, Qiuming; Janes, Trevor; Gjergji, Xhoana; Song, Datong

    2016-09-21

    The synthesis, structure and reactivity of bidentate picolyl N-heterocyclic carbene (NHC) iron compounds were studied. Compounds [FeBr(HL)2]Br (1), [FeBr(HL)(HMDS)] (2) and [FeBr2(HL)] (3) (HL = 1-mesityl-3-(pyridin-2-ylmethyl)imidazol-1-ylidene, HMDS = hexamethyldisilazide) were prepared from H2LBr with suitable amounts of Fe(HMDS)2 or in situ prepared [Fe(HMDS)Br]. The deprotonation of 1 with 2 eq. of LiHMDS gave [FeL2] (4), featuring dearomatized pyridine moieties with exocyclic C-C double bonds. The protonation of 4 with 2 eq. of PPh3·HBr results in the formation of 1. Attempted deprotonation of 3 using benzyl Grignard as the base resulted in transmetalation products [FeBnBr(HL)] (5) and [FeBn2(HL)] (6). Exposure of 6 to CO resulted in the formation of diamagnetic compound [Fe(CO)3(HL)] (7) and dibenzyl ketone. Prolonged exposure of 7 to CO with heating induces pyridine dissociation, affording [Fe(CO)4(HL-κC)] (8). Treatment of compound 6 with an equimolar amount of p-methoxybenzyl bromide yielded homo- and cross-coupling products. PMID:27513216

  2. The stellar content of 30 doradus derived from spatially integrated ultraviolet spectra: A test of spectral synthesis models

    NASA Technical Reports Server (NTRS)

    Vacca, William D.; Robert, Carmelle; Leitherer, Claus; Conti, Peter S.

    1995-01-01

    Using the IUE satellite, we have obtained spatially integrated ultraviolet spectra of three areas within the giant H II region 30 Dor in the Large Magellanic Cloud. The spectra correspond to spatial reginswith sizes of 20 sec x 20 sec, 1 min x 1 min, and 3 min x 3 min, all of which are approximately centered on R136. We have performed a spectral synthesis analysis of the spectra of the two larger regions and compared the results with the known stellar content in these regions. The spectral synthesis models are sensitive to the ultraviolet continuum level, the P Cygni profile of the C Iv wavelength 1550 line, the absorption strength of the Si IV wavelength 1400 line, and the emission strength of the He II wavelength 1640 line. The intrinsic continuum levels and the profiles of these stellar wind lines provide constraints on the age and duration of the starburst episode within a region, as well as on the upper curoff mass of the initial mass function. From our analysis we find that the present-day value of the upper cutoff mass in the 1 min x 1 min and 3 min x 3 min regions has a lower limit of approximately 50 solar mass, a result which is in good agreement with several other recent determinations. The age of the starburst episode must be less than approximately 3 Myr, also in agreement with other estimates. Comparison of the observed total numbers of O and W-R stars with those predicted from the various models favors an instantaneous burst of star formation in the regions. However, the differences between the two burst scenarios we investigated (instantaneous and continuous) are small at such a young age, and distinguishing between the two is difficult. We are now confident that these spectral synthesis models can be used to determine the stellar content of more distant star-forming regions.

  3. Synthesis and NMR Spectral Analysis of Amine Heterocycles: The Effect of Asymmetry on the [superscript 1]H and [superscript 13]C NMR Spectra of N,O-Acetals

    ERIC Educational Resources Information Center

    Saba, Shahrokh; Ciaccio, James A.; Espinal, Jennifer; Aman, Courtney E.

    2007-01-01

    The stereochemical investigation is conducted to give students the combined experience of chemical synthesis of amines and N-heterocycles and structural stereochemical analysis using NMR spectroscopy. Students are introduced to the concept of topicity-stereochemical relationships between ligands within a molecule by synthesizing N,O-acetals.

  4. Isocyanide or nitrosyl complexation to hemes with varying tethered axial base ligand donors: synthesis and characterization.

    PubMed

    Sharma, Savita K; Kim, Hyun; Rogler, Patrick J; A Siegler, Maxime; Karlin, Kenneth D

    2016-09-01

    A series of ferrous-heme 2,6-dimethylphenyl isocyanide (DIMPI) and ferrous-heme mononitrosyl complexes have been synthesized and characterized. The heme portion of the complexes studied is varied with respect to the nature of the axial ligand, including complexes, where it is covalently tethered to the porphyrinate periphery. Reduced heme complexes, [(F8)Fe(II)], [(P(Py))Fe(II)], [(P(Im))Fe(II)], and [(P(ImH))Fe(II)], where F8 = tetrakis(2,6-difluorophenyl)-porphyrinate and P(Py), P(Im), and P(ImH) are partially fluorinated tetraaryl porphyrinates with covalently appended axial base pyridyl/imidazolyl or histamine moieties, were employed; P(ImH) is a new construct. Room temperature addition of DIMPI to these iron(II) complexes affords the bis-isocyanide species [(F8)Fe(II)-(DIMPI)2] in the case of [(F8)Fe(II)], while for the other hemes, mono-DIMPI compounds are obtained, [(P(Py))Fe(II)-(DIMPI)] [(2)-DIMPI], [(P(Im))Fe(II)-(DIMPI)] [(3)-DIMPI], and [(P(ImH))Fe(II)-(DIMPI)] [(4)-DIMPI]. The structures of complexes (3)-DIMPI and (4)-DIMPI have been determined by single crystal X-ray crystallography, where interesting H…F(porphryinate aryl group) interactions are observed. (19)F-NMR spectra determined for these complexes suggest that H…F(porphyrinate aryl groups) attractions also occur in solution, the H atom coming either from the DIMPI methyl groups or from a porphyinate axial base imidazole or porphyrinate pyrrole. Similarly, we have used nitrogen monoxide to generate ferrous-nitrosyl complexes, a five-coordinate species for F8, [(F8)Fe(II)-(NO)], or low-spin six-coordinate compounds [(P(Py))Fe(II)-(NO)], [(P(Im))Fe(II)-(NO)], and [(P(ImH))Fe(II)-(NO)]. The DIMPI and mononitrosyl complexes have also been characterized using UV-Vis, IR, (1)H-NMR, and EPR spectroscopies. PMID:27350154

  5. Synthesis, structures and reactivity of ruthenium nitrosyl complexes containing Kläui's oxygen tripodal ligand.

    PubMed

    Ip, Ho-Fai; Yi, Xiao-Yi; Wong, Wai-Yeung; Williams, Ian D; Leung, Wa-Hung

    2011-11-01

    Ruthenium nitrosyl complexes containing the Kläui's oxgyen tripodal ligand L(OEt)(-) ([CpCo{P(O)(OEt)(2)}(3)](-) where Cp = η(5)-C(5)H(5)) were synthesized and their photolysis studied. The treatment of [Ru(N^N)(NO)Cl(3)] with [AgL(OEt)] and Ag(OTf) afforded [L(OEt)Ru(N^N)(NO)][OTf](2) where N^N = 4,4'-di-tert-butyl-2,2'-bipyridyl (dtbpy) (2·[OTf](2)), 2,2'-bipyridyl (bpy) (3·[OTf](2)), N,N,N'N'-tetramethylethylenediamine (4·[OTf](2)). Anion metathesis of 3·[OTf](2) with HPF(6) and HBF(4) gave 3·[PF(6)](2) and 3·[BF(4)](2), respectively. Similarly, the PF(6)(-) salt 4·[PF(6)](2) was prepared by the reaction of 4·[OTf](2) with HPF(6). The irradiation of [L(OEt)Ru(NO)Cl(2)] (1) with UV light in CH(2)Cl(2)-MeCN and tetrahydrofuran (thf)-H(2)O afforded [L(OEt)RuCl(2)(MeCN)] (5) and the chloro-bridged dimer [L(OEt)RuCl](2)(μ-Cl)(2) (6), respectively. The photolysis of complex [2][OTf](2) in MeCN gave [L(OEt)Ru(dtbpy)(MeCN)][OTf](2) (7). Refluxing complex 5 with RNH(2) in thf gave [L(OEt)RuCl(2)(NH(2)R)] (R = tBu (8), p-tol (9), Ph (10)). The oxidation of complex 6 with PhICl(2) gave [L(OEt)RuCl(3)] (11), whereas the reduction of complex 6 with Zn and NH(4)PF(6) in MeCN yielded [L(OEt)Ru(MeCN)(3)][PF(6)] (12). The reaction of 3·[BF(4)](2) with benzylamine afforded the μ-dinitrogen complex [{L(OEt)Ru(bpy)}(2)(μ-N(2))][BF(4)](2) (13) that was oxidized by [Cp(2)Fe]PF(6) to a mixed valence Ru(II,III) species. The formal potentials of the RuL(OEt) complexes have been determined by cyclic voltammetry. The structures of complexes 5,6,10,11 and 13 have been established by X-ray crystallography. PMID:21927766

  6. Synthesis, spectral characterization, DNA interaction, radical scavenging and cytotoxicity studies of ruthenium(II) hydrazone complexes.

    PubMed

    Mohanraj, Maruthachalam; Ayyannan, Ganesan; Raja, Gunasekaran; Jayabalakrishnan, Chinnasamy

    2016-05-01

    Three new ruthenium(II) complexes with hydrazone ligands, furan-2-carboxylic acid (2,4-dihydroxy-benzylidene)-hydrazide (HL(1)), furan-2-carboxylic acid [4-(ethyl-propyl-amino)-2-hydroxy-benzylidene]-hydrazide (HL(2)) and furan-2-carboxylic acid (3-ethoxy-2-hydroxy-benzylidene)-hydrazide (HL(3)) were synthesized and characterized by various spectro-analytical techniques. The hydrazone ligands act as a tridendate ligand with ONO as the donor sites and are preferably found in the enol form in all the complexes. The molecular structure of the ligands was determined by single crystal X-ray diffraction technique. The interaction of the ligands and the complexes with CT-DNA were evaluated by an absorption titration method which revealed that the compounds interact with CT-DNA through intercalation. Gel electrophoresis assay demonstrated the ability of the complexes to cleave the calf thymus DNA hydrolytically. Antioxidant studies showed that the ruthenium(II) complexes have a strong radical-scavenging properties. Further, the cytotoxic effect of the compounds examined on cancerous cell lines showed that the complexes exhibited substantial anticancer activity. PMID:26974577

  7. The dynamic atmospheres of red giant stars. Spectral synthesis in high resolution

    NASA Astrophysics Data System (ADS)

    Nowotny, W.

    2005-11-01

    other hand, reproducing the temporal variability of various molecular line profiles is a crucial test for the atmospheric models. The comparison of modelling results with observations (i) tells us whether the models resemble structures and dynamics of real AGB atmospheres, (ii) may put constraints on probable mass-loss mechanisms, (iii) may provide information on the interrelation of pulsation and mass loss, and (iv) may be a criterion to constrain the stellar parameters for observed targets. In practice, a 'dynamic model atmosphere' provides snapshots of the time-dependent atmospheric structure (rho, T, p, u_gas, etc.) at several instances of time. On the basis of these and under the assumption of LTE, opacities for various sources are calculated (especially the molecular contributions by using line lists), which serve as input for the subsequent radiative transfer computations. Because of the diverse movements of atmospheric layers in different depths, it is essential to include the influence of macroscopic velocities on the interaction between matter and radiation in this step of the spectral synthesis. Thus, a code for solving spherical radiative transfer which takes into account velocity effects was used to model the complex line profiles and their variations. One major goal for this thesis was to find out if the used dynamic model atmospheres can reproduce the global atmospheric structures of typical pulsating and mass-losing AGB stars (Mira variables), especially the characteristic velocity behaviours in zones of different atmospheric depths. This should allow the simultaneous modelling of spectral lines originating in various layers with one single dynamical model. The only C-rich Mira with a reasonable time series of high-resolution NIR spectroscopy, S Cep, served as the reference for the chosen atmospheric model. Synthetic spectra, containing selected CO (dv=1,2,3) and CN lines, were calculated based on several phases of this model. The results of this

  8. A new fullerene complexation ligand: N-pyridylfulleropyrrolidine.

    PubMed

    Tat, Fatma T; Zhou, Zhiguo; MacMahon, Shaun; Song, Fayi; Rheingold, Arnold L; Echegoyen, Luis; Schuster, David I; Wilson, Stephen R

    2004-07-01

    The subject of this paper is a new fullerene building block design with the potential for defined geometry and good electronic communication. The synthesis and characterization of a new pyridinofullerene ligand capable of forming axially symmetric complexes with metalloporphyrins is reported. X-ray structural and molecular modeling studies, (1)H NMR, UV-vis spectroscopy, electrochemistry studies, and fluorescence quenching data support the formation of a strong complex between the new ligand and the metal center of ZnTPP. On the basis of computational studies, the highest occupied molecular orbital (HOMO) of this ligand is significantly different from a model compound with insulating carbons between the pyridine and the fullerene. The N-pyridinium fulleropyrrolidine salts of the new ligand and model compound were also prepared and their spectral and electrochemical properties are reported. PMID:15230581

  9. Polyoxometalates functionalized by bisphosphonate ligands: synthesis, structural, magnetic, and spectroscopic characterizations and activity on tumor cell lines.

    PubMed

    El Moll, Hani; Zhu, Wei; Oldfield, Eric; Rodriguez-Albelo, L Marleny; Mialane, Pierre; Marrot, Jérôme; Vila, Neus; Mbomekallé, Israel Martyr; Rivière, Eric; Duboc, Carole; Dolbecq, Anne

    2012-07-16

    We report the synthesis and characterization of eight new Mo, W, or V-containing polyoxometalate (POM) bisphosphonate complexes with metal nuclearities ranging from 1 to 6. The compounds were synthesized in water by treating Mo(VI), W(VI), V(IV), or V(V) precursors with biologically active bisphosphonates H(2)O(3)PC(R)(OH)PO(3)H(2) (R = C(3)H(6)NH(2), Ale; R = CH(2)S(CH(3))(2), Sul and R = C(4)H(5)N(2), Zol, where Ale = alendronate, Sul = (2-Hydroxy-2,2-bis-phosphono-ethyl)-dimethyl-sulfonium and Zol = zoledronate). Mo(6)(Sul)(2) and Mo(6)(Zol)(2) contain two trinuclear Mo(VI) cores which can rotate around a central oxo group while Mo(Ale)(2) and W(Ale)(2) are mononuclear species. In V(5)(Ale)(2) and V(5)(Zol)(2) a central V(IV) ion is surrounded by two V(V) dimers bound to bisphosphonate ligands. V(6)(Ale)(4) can be viewed as the condensation of one V(5)(Ale)(2) with one additional V(IV) ion and two Ale ligands, while V(3)(Zol)(3) is a triangular V(IV) POM. These new POM bisphosphonates complexes were all characterized by single-crystal X-ray diffraction. The stability of the Mo and W POMs was studied by (31)P NMR spectroscopy and showed that all compounds except the mononuclear Mo(Ale)(2) and W(Ale)(2) were stable in solution. EPR measurements performed on the vanadium derivatives confirmed the oxidation state of the V ions and evidenced their stability in aqueous solution. Electrochemical studies on V(5)(Ale)(2) and V(5)(Zol)(2) showed reduction of V(V) to V(IV), and magnetic susceptibility investigations on V(3)(Zol)(3) enabled a detailed analysis of the magnetic interactions. The presence of zoledronate or vanadium correlated with the most potent activity (IC(50)~1-5 μM) against three human tumor cell lines. PMID:22725619

  10. MM Quadruply Bonded Complexes Supported by Vinylbenzoate Ligands: Synthesis, Characterization, Photophysical Properties and Application as Synthons

    PubMed Central

    Brown-Xu, Samantha E.; Chisholm, Malcolm H.; Durr, Christopher B.; Spilker, Thomas F.; Young, Philip J.

    2015-01-01

    From the reactions between M2(TiPB)4 compounds and meta and para – vinylbenzoic acids (2 equiv) in toluene at room temperature the compounds trans-M2(TiPB)2L2, where L = m-vinylbenzoate 1A (M = Mo) and 1B (M = W) and TiPB = 2,4,6-triisopropylbenzoate, and where L = p-vinylbenzoate 2A (M = Mo) and 2B (M = W) have been isolated. Compounds 1A and 2A have been shown to undergo Heck carbon-carbon coupling reactions with phenyliodide to produce trans-Mo2(TiPB)2(O2CC6H4-m-CH=CH-C6H5)2, 3A and trans-Mo2(TiPB)2(O2CC6H4-p-CH=CH-C6H5)2, 4A. The molybdenum compounds 1A and 2A have been structurally characterized by single crystal X-ray crystallography. All the new compounds have been characterized by 1H NMR, IR, UV-Visible absorption and emission spectroscopy, high resolution MALDITOF MS, fs- and ns- transient absorption spectroscopy and fs- time-resolved IR spectroscopy. Electronic structure calculations employing density functional theory, DFT, and time-dependent DFT have been employed to aid in the interpretation of spectral data. All compounds show intense absorptions in the visible region corresponding to M2δ to Lπ* charge transfer transitions. The lifetimes of the 1MLCT state fall in the range of 1 – 10 ps and for the molybdenum complexes the T1 states are 3δδ* with lifetimes ~50 μs while for the tungsten complexes the T1 are 3 MLCT with lifetimes in the range of 3 – 10 ns. PMID:26417424

  11. Synthesis and structural evaluation of five coordination complexes of benzenepentacarboxylic acid with aza-donor ligands

    NASA Astrophysics Data System (ADS)

    Shimpi, Manishkumar R.; Biswas, Sharmita Nandy; Sarkar, Sohini; Pedireddi, V. R.

    2016-06-01

    Synthesis and structural features of five new coordination assemblies, [Co(bpyH)(H2O)5](BPCH)·(bpyH2)0.5·(H2O) (1a), [{Cu(H2O)3}·{Cu0.5(bpy)0.5(H2O)0.5}2(μ-BPCH)] (1b), [{Cd0.5(BPCH)}2·{Cd0.5(bpy)(H2O)2}2]·6(H2O) (1c), [Cu(BPCH2)(bpyeaH)]·2(H2O) (1d) and [Cd2 (bpyea)0.5(oxalate)0.5(μ-BPC) (H2O)]·(bpyeaH2)·2(H2O) (1e), have been reported. All the assemblies were prepared by co-crystallization of benzenepentacarboxylic acid (BPCH5) either with 4,4‧-bipyridine (bpy) or 1,2-bis(4-pyridyl)ethane (bpyea) in the presence of a transition metal ion (either Co(II), Cu(II) or Cd(II)) as the case may be. All the five compounds were synthesized by hydrothermal method and structures were determined by single crystal X-ray diffraction. All the obtained compounds, 1a-1e, exhibit distinct 3-D polymeric architectures either in the form of stacked layers or host-guest networks in which water molecules play a pivotal role providing additional stabilization by coordinate bonds as well as hydrogen bonds. Other non-covalent interactions such as C-H … π and π … π stacking also participate in the formation of exotic 3-D structures of these complexes.

  12. Mixed Ligand Complexes of N-Methyl-N-phenyl Dithiocarbamate: Synthesis, Characterisation, Antifungal Activity, and Solvent Extraction Studies of the Ligand

    PubMed Central

    Ekennia, Anthony C.; Onwudiwe, Damian C.; Ume, Cyril; Ebenso, Eno E.

    2015-01-01

    A series of mixed ligand dithiocarbamate complexes with a general formula [ML2(py)2], where M = Mn(II), Co(II), Ni(II), and Cu(II), py = pyridine, and L = N-methyl-N-phenyl dithiocarbamate have been prepared and characterised by elemental analysis, FTIR and Uv spectroscopy, magnetic moment, and thermogravimetric and conductance analysis. The infrared spectra showed that symmetrical bidentate coordination occurred with the dithiocarbamate moiety through the sulfur atoms, while neutral monodentate coordination occurred through the nitrogen atom for the pyridine molecule in the complexes. The electronic spectra, elemental analysis, and magnetic moment results proved that the complexes adopted octahedral geometry. The conductance measurement showed that the complexes are nonelectrolytes proving their nonionic nature. The compounds were screened for three human pathogenic fungi: Aspergillus flavus, Aspergillus niger, and Candida albicans. The cobalt complex showed the best antifungal activity among the test compounds. Liquid-liquid extractive abilities of the ligand towards copper and nickel ions in different solvent media were investigated. The ligand showed a strong binding affinity towards the metals ions with an extractive efficiency of about 99%. PMID:26543441

  13. Hydrothermal synthesis of Group 13 metal trifluoride complexes with neutral N-donor ligands.

    PubMed

    Bhalla, Rajiv; Levason, William; Luthra, Sajinder K; McRobbie, Graeme; Monzittu, Francesco M; Palmer, Jazmyn; Reid, Gillian; Sanderson, George; Zhang, Wenjian

    2015-05-28

    The reactions of the hydrated Group 13 fluorides, MF3·3H2O (M = Al, Ga or In) with 2,2':6',2''-terpyridyl, 2,2'-bipyridyl or 1,10-phenanthroline under hydrothermal conditions (180 °C/15 h) produced high yields of the complexes [MF3(terpy)]·3H2O, [MF3(bipy)(OH2)]·2H2O and [MF3(phen)(OH2)]. X-Ray crystal structures of [M'F3(terpy)]·3H2O (M' = Al or Ga), [M'F3(bipy)(OH2)]·2H2O and [GaF3(phen)(OH2)] show that all of them contain distorted octahedral geometries at the metal with mer-trifluoride coordination. Extensive H-bonding (FH-OH) links the molecules. The complexes have been further characterised by microanalysis, IR, (1)H, (19)F{(1)H} and (27)Al NMR spectroscopy. In contrast, reactions of the trifluorides with the acyclic triamine, N,N,N',N',N''-pentamethyldiethylenetriamine, under similar hydrothermal conditions results in cleavage of the triamine and ring-closure to form the 1,1,4-trimethylpiperazinium cation, [⊂Me2N(CH2)2NMe(CH2)2](+), with fluorometallate anions, and confirmed by X-ray analysis of [⊂Me2N(CH2)2NMe(CH2)2]2[Al2F8(OH2)2]·2H2O. The strongly H-bonded [GaF3(terpy)]·3H2O was also obtained by Cl/F exchange from [GaCl3(terpy)] and [NBu4]F or [K(2,2,2-crypt)]F. Crystallisation of a mixture of [NH4][PF6] and [GaF3(terpy)]·3H2O from aqueous solution produced the edge-bridged cationic complex, [{Ga(terpy)F}2(μ-F)2][PF6]2. The synthesis of the more sterically bulky [GaCl3((t)Bu3-terpy)] ((t)Bu3-terpy = 4,4'4''-tris-(t)Bu-2,2':6',2''-terpyridyl) and the crystal structure of [GaCl2((t)Bu3-terpy)][GaCl4], which contains a trigonal bipyramidal cation, are also reported. PMID:25921724

  14. Synthesis, Characterization, and Interaction with Biomolecules of Platinum(II) Complexes with Shikimic Acid-Based Ligands

    PubMed Central

    Peng, Yan; Zhang, Min-Min; Chen, Zhen-Feng; Hu, Kun; Liu, Yan-Cheng; Chen, Xia; Liang, Hong

    2013-01-01

    Starting from the active ingredient shikimic acid (SA) of traditional Chinese medicine and NH2(CH2)nOH, (n = 2–6), we have synthesized a series of new water-soluble Pt(II) complexes PtLa–eCl2, where La–e are chelating diamine ligands with carbon chain covalently attached to SA (La–e = SA-NH(CH2)nNHCH2CH2NH2; La, n = 2; Lb, n = 3; Lc, n = 4; Ld, n = 5; Le, n = 6). The results of the elemental analysis, LC-MS, capillary electrophoresis, and 1H, 13C NMR indicated that there was only one product (isomer) formed under the present experimental conditions, in which the coordinate mode of PtLa–eCl2 was two-amine bidentate. Their in vitro cytotoxic activities were evaluated by MTT method, where these compounds only exhibited low cytotoxicity towards BEL7404, which should correlate their low lipophilicity. The interactions of the five Pt(II) complexes with DNA were investigated by agarose gel electrophoresis, which suggests that the Pt(II) complexes could induce DNA alteration. We also studied the interactions of the Pt(II) complexes with 5′-GMP with ESI-MS and 1H NMR and found that PtLbCl2, PtLcCl2, and PtLdCl2 could react with 5′-GMP to form mono-GMP and bis-GMP adducts. Furthermore, the cell-cycle analysis revealed that PtLbCl2, PtLcCl2 cause cell G2-phase arrest after incubation for 72 h. Overall, these water-soluble Pt(II) complexes interact with DNA mainly through covalent binding, which blocks the DNA synthesis and replication and thus induces cytotoxicity that weakens as the length of carbon chain increases. PMID:23533373

  15. Novel glycolipid TLR2 ligands of the type Pam2Cys-α-Gal: synthesis and biological properties.

    PubMed

    Thomann, Jean-Sébastien; Monneaux, Fanny; Creusat, Gaëlle; Spanedda, Maria Vittoria; Heurtault, Béatrice; Habermacher, Chloé; Schuber, Francis; Bourel-Bonnet, Line; Frisch, Benoît

    2012-05-01

    A more complete understanding of the mechanism of action of TLR agonists has fueled the investigation of new synthetic immunoadjuvants. In this context, we designed and synthesized glycolipids of the type Pam(2)Cys-α-Galactose as novel immunoadjuvants. Their synthesis required modifying a hydrophobic tBoc-[2,3-bispalmitoyloxy-(2R)-propyl]-R-cysteinyl moiety, i.e. the minimal structure required for TLR2 agonist activity, by addition of a hydrophilic head, either an α-Galactosylpyranose or an α-Galactosylfuranose to gain respectively Pam(2)CGalp and Pam(2)CGalf. While preparing a carbohydrate building block, an unexpected stereoselectivity was observed during a halide ion-catalytic process on a protected galactofuranose: the alpha anomer was obtained with surprisingly high selectivity (α/β ratio>9) and with good isolated yield (51%). The TLR2 binding properties of Pam(2)CGalp and Pam(2)CGalf were then fully evaluated. Their efficiency in triggering the proliferation of BALB/c mouse splenocytes was also compared to that of Pam(2)CAG and Pam(3)CAG, two well-established ligands of TLRs. Moreover, the maturation state of murine dendritic cells previously incubated with either Pam(2)CGalp or Pam(2)CGalf was monitored by flow cytometry and compared to that induced by lipopolysaccharide. Pam(2)CGalp and Pam(2)CGalf were found to be equivalent TLR2 agonists, and induced splenocyte proliferation and DC maturation. With very similar activity, Pam(2)CGalp and Pam(2)CGalf were also 10-fold to 100-fold better than Pam(2)CAG and Pam(3)CAG at inducing B cell proliferation. This represents the first time a glucidic head has been added to the tBoc-[2,3-bispalmitoyloxy-(2R)-propyl]-R-cysteinyl moiety whilst maintaining the immunomodulating activity. This should greatly enrich the data available on Pam(2)C structure/activity relationships. PMID:22483966

  16. Homoleptic borates and aluminates containing the difluorophosphato ligand - [M(O2PF2)x](y-) - synthesis and characterization.

    PubMed

    Schulz, Christoph; Eiden, Philipp; Klose, Petra; Ermantraut, Andreas; Schmidt, Michael; Garsuch, Arnd; Krossing, Ingo

    2015-04-21

    Weakly coordinating anions (WCAs) with the difluorophosphato ligand (O2PF2) were the target of this study. Initial experiments were conducted towards the preparation of homoleptic aluminates of the well-studied [Al(OR)4](-)-type. The preparation of the initial target structure Li[Al(O2PF2)4] failed due to the remaining Lewis acidic character of the central aluminum atom. Instead, the formation of Li3[Al(O2PF2)6] and Al(O2PF2)3 was observed with hexacoordinate aluminum atoms and verified by NMR, IR and X-ray crystallography. A possible mechanism towards these compounds was postulated in the solvent induced dismutation of the tetracoordinate Li[Al(O2PF2)4]. A singly charged WCA was realized by the exchange of the central aluminum atom for boron. The [B(O2PF2)4](-) anion was prepared starting from BH3·S(CH3)2 and boron tribromide leading to the protic room temperature Ionic Liquid (IL) [H(S(CH3)2)][B(O2PF2)4] and the neat liquid Brønsted acid H[B(O2PF2)4], respectively, representing a significantly improved synthesis with regard to the first experiments of Dove et al. The basicity of the [B(O2PF2)4](-) anion and its WCA quality were investigated on the basis of the IR-spectroscopic NH-scale and the salt [H(N(Oct)3)][B(O2PF2)4] that places it better than all oxyanions and close to the carboranate based WCAs. A pathway to the solvent free pure Li[B(O2PF2)4] salt was established on a multi-gram scale with excellent purities enabling electrochemical applications (verified by NMR, IR, X-ray crystallography and cyclovoltammetry). PMID:25785817

  17. Subnanometer Control of Mean Core Size during Mesofluidic Synthesis of Small (D(core) < 10 nm) Water-Soluble, Ligand-Stabilized Gold Nanoparticles.

    PubMed

    Elliott, Edward W; Haben, Patrick M; Hutchison, James E

    2015-11-01

    A convenient, single-step synthesis is reported that produces ligand-stabilized, water-soluble gold nanoparticles (AuNPs) with subnanometer-level precision of the mean core diameter over a range of 2-9 nm for a series of desired surface chemistries. The synthesis involves the reduction of a Au(III) species with sodium borohydride in the presence of a functionalized alkyl thiosulfate (Bunte salt) to yield thiolate-protected AuNPs. A key advantage of this synthesis is that simply adjusting the pH of the gold salt solution leads to control over the AuNP core size. The speciation of Au(III), and therefore the kinetics for its reduction and the core size produced, depends upon pH. The use of pH as the sole variable to control core size is a more reliable and convenient method than traditional approaches that rely on adjusting the concentrations and ratios of ligand, metal salt, and reducing agent. The average core size increased as the pH was raised for each ligand studied. Because the influence of pH was different for each of the ligands, working curves were plotted for each ligand to identify conditions to synthesize particles with specific, targeted core diameters. Using this approach, reaction conditions can be rapidly optimized using a combination of a mesofluidic reactor and small-angle X-ray scattering (SAXS) size analysis. The use of the mesofluidic reactor was needed to ensure fast mixing given the rapid kinetics for core formation. Using the reactor, it is possible to obtain reproducible sizes across multiple syntheses (<1-2% core size variation) and subnanometer control of the mean core dimensions. The synthetic method demonstrated here provides an attractive alternative to two-step syntheses involving ligand exchange because it is more efficient and eliminates the possibility of nanoparticle core size changes during exchange steps. This approach enables the development of "size ladders" of particles with the same surface chemistry for investigations of

  18. Synthesis, spectroscopic characterization and DNA nuclease activity of Cu(II) complexes derived from pyrazolone based NSO-donor Schiff base ligands

    NASA Astrophysics Data System (ADS)

    Vyas, Komal M.; Joshi, Rushikesh G.; Jadeja, R. N.; Ratna Prabha, C.; Gupta, Vivek K.

    2011-12-01

    Two neutral mononuclear Cu(II) complexes have been prepared in EtOH using Schiff bases derived from 4-toluoyl pyrazolone and thiosemicarbazide. Both the ligands have been characterized on the basis of elemental analysis, IR, 1H NMR, 13C NMR and mass spectral data. The molecular geometry of one of these ligands has been determined by single crystal X-ray study. It reveals that these ligands exist in amine-one tautomeric form in the solid state. Microanalytical data, Cu-estimation, molar conductivity, magnetic measurements, IR, UV-Visible, FAB-Mass, TG-DTA data and ESR spectral studies were used to confirm the structures of the complexes. Electronic absorption and IR spectra of the complexes suggest a square-planar geometry around the central metal ion. The interaction of complexes with pET30a plasmid DNA was investigated by spectroscopic measurements. Results suggest that the copper complexes bind to DNA via an intercalative mode and can quench the fluorescence intensity of EB bound to DNA. The interaction between the complexes and DNA has also been investigated by agarose gel electrophoresis, interestingly, we found that the copper(II) complexes can cleave circular plasmid DNA to nicked and linear forms.

  19. Mixed ligand palladium(II) complexes of 6-methoxy-2-oxo-1,2-dihydroquinoline-3-carbaldehyde 4N-substituted thiosemicarbazones with triphenylphosphine co-ligand: synthesis, crystal structure and biological properties.

    PubMed

    Ramachandran, Eswaran; Senthil Raja, Duraisamy; Bhuvanesh, Nattamai S P; Natarajan, Karuppannan

    2012-11-21

    A series of new 6-methoxy-2-oxo-1,2-dihydroquinoline-3-carbaldehyde 4N-substituted thiosemicarbazone ligands (H2L1–H2L5) and their corresponding palladium(II) complexes [Pd(L1)(PPh3)] (1), [Pd(L2)(PPh3)] (2), [Pd(HL3)(PPh3)]Cl (3), [Pd(L4)(PPh3)] (4) and [Pd(L5)(PPh3)] (5), have been synthesized in order to evaluate the effect of terminal N-substitution in thiosemicarbazone moiety on coordination behaviour and biological activity. The new ligands and their corresponding complexes were characterized by analytical and various spectral techniques. The molecular structure of the complexes 2–5 were characterized by single crystal X-ray diffraction studies which revealed that the ligands H2L2, H2L4 and H2L5 are coordinated to palladium(II) as binegative tridentate (ONS2−) by forming six and five member rings whereas, the ligand H2L3 coordinated to Pd(II) as uninegative tridentate (ONS−). The interactions of the new complexes with calf thymus DNA (CT-DNA) have been evaluated by absorption and ethidium bromide (EB) competitive studies which revealed that complexes 1–5 could interact with CT-DNA through intercalation. Further, the interactions of the complexes with bovine serum albumin (BSA) were also investigated using UV-visible, fluorescence and synchronous fluorescence spectroscopic methods, which showed that the new complexes could bind strongly with BSA. Antioxidant studies showed that all the complexes have a strong antioxidant activity against 2-2′-diphenyl-1-picrylhydrazyl (DPPH) radical and 2,2′-azino-3-ethylbenzthiazoline-6-sulfonic acid diammonium salt (ABTS) cation radical. In addition, in vitro cytotoxicity of the complexes against human lung cancer (A549) cell line was assayed which showed that 4 has higher cytotoxic activity than the rest of the complexes and cisplatin. PMID:22864662

  20. Synthesis and spectroscopic characterization of some transition metal complexes of a new hexadentate N 2S 2O 2 Schiff base ligand

    NASA Astrophysics Data System (ADS)

    Sarkar, Saikat; Dey, Kamalendu

    2005-11-01

    A novel interesting hexadentate dibasic N 2S 2O 2 donor Schiff base ligand, H4dcsalpte, was synthesized by the condensation of 3-formylsalicylic acid and 1,2-di( o-aminophenylthio)ethane and characterized. The reactions of the ligand with different metal(II/III)salts under varied reaction conditions afforded a series of metal complexes. The ligand, H4dcsalpte, behaves either as a dibasic or neutral hexadentate one, depending on the reaction conditions. Structural investigations on the ligand and their complexes have been made based on elemental analyses, molar conductance values, magnetic moment values, cryomagnetic and spectral (UV-vis, IR, 1H NMR, and Mössbauer) data. Based on magnetic susceptibility, Mössbauer and electronic spectral data the iron(III) complex [Fe III( H2dcsalpte)]ClO 4 ( 8), isolated in the present investigation, it is inferred that the spin states 5/2 and 1/2 are in equilibrium. Similarly a tri-iron(III) complex [Fe III3( H2dcsalpte)( H3dcsalpte)Cl 3]Cl 3 ( 7), isolated in this study, has been inferred to contain two iron(III) sites in tetrahedral environment and one in the octahedral environment. The aerial oxidation of an equimolar mixture of H4dcsalpte and Co(CH 3COO) 2·4H 2O in ethanol under reflux gave two products, [Co( H2dcsalpte)]CH 3COO ( 10) and [( Hbtcsaldm)Co( Hbvcsaldm)] ( 11), a cobalt(III) complex bound to two dissimilar tridentate NSO donor ligands formed as a result of the oxidative cleavage of the C sbnd S bond. In the complex 11, Hbtcsaldm stands for the dianion of the tridentate Schiff base ligand N-(2'-benzenethiol)-3-carboxysalicylaldimine and Hbvcsaldm stands for the mono anion of the tridentate Schiff base ligand N-(benzene-2'-S-vinyl)-3-carboxysalicylaldimine, both being formed as a result of the oxidative cleavage of H4dcsalpte.

  1. Synthesis and luminescence of lanthanide complexes of a branched macrocyclic ligand containing 2,2[prime]-bipyridine and 9-methyl-1,10-phenanthroline subunits

    SciTech Connect

    Sabbatini, N.; Guardigli, M.; Manet, I.; Bolletta, F. ); Ziessel, R. )

    1994-03-02

    The synthesis of the branched-macrocyclic ligand 1 incorporating two 2,2[prime]-bipyridine units in the macrocycle and two 9-methyl-1,10-phenanthroline units in the branches is described as well as the synthesis and the photophysical properties of its Eu[sup 3+], Tb[sup 3+], and Gd[sup 3+] complexes. These complexes do not decompose in water in contrast to those of the related ligand containing 2,2[prime]-bipyridine instead of 1,10-phenanthroline. They show intense absorption bands in the UV region due to absorption in the ligand. The emission spectra of the [Eu[contained in]1][sup 3+] and [Tb[contained in]1][sup 3+] complexes obtained upon ligand excitation show the usual Eu[sup 3+] and Tb[sup 3+] transitions. The pattern of the emission spectrum of the [Eu[contained in]1][sup 3+] complex allows one to assess a low (presumably C[sub 2]) symmetry as the probable site symmetry of the metal ion in the complex. For [Eu[contained in]1][sup 3+] and [Tb[contained in]1][sup 3+], the metal luminescence excitation spectra in water match the ligand absorption spectra while in methanol the absorption due to the phenanthroline is missing. This suggests that in water the efficiency of the ligand-to-metal energy transfer is similar for the two chromophores while in methanol phenanthroline transfers energy to the metal ion less efficiently than bipyridine. The luminescence quantum yield values in water and methanol confirm this interpretation. The lifetimes of the Eu[sup 3+] and Tb[sup 3+] emitting state indicate that the shielding of the metal ion from solvent molecules is rather inefficient. For the [Tb[contained in]1][sup 3+] complex the lifetimes are temperature dependent which is attributed to the presence of an equilibrium between the metal emitting state and triplet excited states of the ligand; this process is most likely responsible for the low luminescence quantum yields and the oxygen effect on the Tb[sup 3+] luminescence.

  2. Synthesis, spectral characterization and biological evaluation of copper(II) and nickel(II) complexes with thiosemicarbazones derived from a bidentate Schiff base

    NASA Astrophysics Data System (ADS)

    Chandra, Sulekh; Bargujar, Savita; Nirwal, Rita; Yadav, Neesha

    2013-04-01

    Complexes of copper(II) and nickel(II) of general composition M(L)2X2, have been synthesized with the ligand 1-Tetralone thiosemicarbazone (where L = 1-Tetralone thiosemicarbazone and X=Cl,1/2SO42-). The molar conductance of the complexes in fresh solution of DMSO lies in the range of 10-20 Ω-1 cm2 mol-1 indicating their non-electrolytic behavior. Thus, the complexes may be formulated as [M(L2)X2]. Ligand was characterized by mass, NMR, IR and single crystallographic studies. All the complexes were characterized by elemental analyses, magnetic moments, IR, electronic and EPR spectral studies. The IR spectral data of ligand indicated the involvement of sulfur and azomethine nitrogen in coordination to the central metal ion. The copper(II) and nickel(II) complexes were found to have magnetic moments1.93-1.96 BM and 2.91-2.94 BM corresponding to one and two unpaired electrons respectively. On the basis of molar conductance, EPR, electronic and infrared spectral studies, a tetragonal geometry has been assigned for Cu(II) chloride complex and trigonal bipyramidal to Cu(II) sulfate complex but an octahedral geometry for Ni(II) complexes. Newly synthesized ligand and its Cu(II) and Ni(II) complexes have also been screened against different bacterial and fungal species.

  3. Iron(III) complex of N-phenylethylenediamine derivative of amine bis(phenol) ligand as model for catechol dioxygenase: Synthesis, characterization and complexation studies

    NASA Astrophysics Data System (ADS)

    Poureskandari, Maryam; Safaei, Elham; Maryam Sajjadi, S.; Karimpour, Touraj; Jaglicic, Zvonko; Lee, Yong-Ill

    2015-08-01

    A new amine bis(phenol) ligand (HLPEA), was synthesized and characterized by IR, 1H NMR spectroscopic techniques and elemental analyses. The mononuclear iron(III) complex (FeLPEA) of this ligand has been prepared and characterized by IR and UV-Vis spectroscopic techniques, ESI-MS, elemental analyses and magnetic susceptibility studies. The molecular mass of complex was determined by ESI-MS which is corresponding to a mononuclear iron(III) complex consist of amine bis(phenolate) ligand coordinated to Fe(III) including chlorine atoms and solvent molecule. The variable temperature magnetic susceptibility indicates paramagnetic character of complex. To determine the formation constant of the complex, multivariate hard modeling method was applied on spectral data collected throughout the titration of Fe(III) with ligand. FeLPEA shows good catalytic activity in cleavage oxygenation of 3,5-di-tert-butyl catechol in the presence of dioxygen at room temperature with a nearly complete conversion and particularly extradiol cleavage mechanism.

  4. Rhenium tetrazolato complexes coordinated to thioalkyl-functionalised phenanthroline ligands: synthesis, photophysical characterisation, and incubation in live HeLa cells.

    PubMed

    Werrett, Melissa V; Wright, Phillip J; Simpson, Peter V; Raiteri, Paolo; Skelton, Brian W; Stagni, Stefano; Buckley, Alysia G; Rigby, Paul J; Massi, Massimiliano

    2015-12-21

    Three new complexes of formulation fac-[Re(CO)3(diim)L], where diim is either 1,10-phenanthroline or 1,10-phenanthroline functionalised at position 5 by a thioalkyl chain, and L is either a chloro or aryltetrazolato ancillary ligand, were synthesised and photophysically characterised. The complexes exhibit phosphorescent emission with maxima around 600 nm, originating from triplet metal-to-ligand charge transfer states with partially mixed ligand-to-ligand charge transfer character. The emission is relatively long-lived, within the 200-400 ns range, and with quantum yields of 2-4%. The complexes were trialed as cellular markers in live HeLa cells, along with two previously reported rhenium tetrazolato complexes bound to unsubstituted 1,10-phenanthroline. All five complexes exhibit good cellular uptake and non-specific perinuclear localisation. Upon excitation at 405 nm, the emission from the rhenium complexes could be clearly distinguished from autofluorescence, as demonstrated by spectral detection within the live cells. Four of the complexes did not appear to be toxic, however prolonged excitation could result in membrane blebbing. No major sign of photobleaching was detected upon multiple imaging on the same cell sample. PMID:26563409

  5. Synthesis, characterization and cytotoxicity of rare earth metal ion complexes of N,N‧-bis-(2-thiophenecarboxaldimine)-3,3‧-diaminobenzidene, Schiff base ligand

    NASA Astrophysics Data System (ADS)

    Shakir, Mohammad; Abbasi, Ambreen; Faraz, Mohammad; Sherwani, Asif

    2015-12-01

    Lanthanide complexes of La3+, Pr3+, Nd3+, Gd3+, Er3+ of general formula [Ln2 L(H2O)4(NO3)4](NO3)2·2H2O have been synthesized from Schiff base, N,N‧-bis-(2-thiophenecarboxaldimine)-3,3‧-diaminobenzidene. The complexes were characterized by elemental analysis, molar conductance, UV-Vis, fluorescence, FT-IR,1H NMR, mass spectroscopy, EDX, SEM and thermal analysis. FT-IR spectral data suggested that ligand coordinate with metal ions through azomethine nitrogen and uncondensed amino group. Molar conductance data revealed 1:2 electrolytic nature of complexes. From the analytical data, the stoichiometry of the complexes was found to be 1:2 (ligand:metal). Thephysico-chemical data suggested eight coordination number for Ln(III)Schiffbase complexes. SEM analysis shows morphological changes in the surfaces of complexes as compared to free ligand. Thermal decomposition profiles were consistent with proposed formulations. The anticancer activity of the complexes and theSchiffbase ligand has been studied towards human cervical cancer celllines (HeLa) and human breast cancer cell lines (MCF-7) and it was found that complexes exhibited greater activity than theSchiffbase.

  6. Synthesis, spectroscopic, antimicrobial, DNA binding and cleavage studies of some metal complexes involving symmetrical bidentate N, N donor Schiff base ligand

    NASA Astrophysics Data System (ADS)

    Arish, D.; Nair, M. Sivasankaran

    2011-11-01

    The Schiff base ligand, N, N'-bis-(4-isopropylbenzaldimine)-1,2-diaminoethane (L), obtained by the condensation of 4-isopropylbenzaldehyde and 1,2-diaminoethane, has been used to synthesize the complexes of the type [ML 2X 2] [M = Co(II), Ni(II) and Zn(II); X = Cl and OAc]. The newly synthesized ligand (L) and its complexes have been characterized on the basis of elemental analyses, mass, 1H and 13C-NMR, molar conductance, IR, UV-vis, magnetic moment, CV and thermal analyses, powder XRD and SEM. IR spectral data show that the ligand is coordinated to the metal ions in a bidentate manner. The geometrical structures of these complexes are found to be octahedral. Interestingly, reaction with Cu(II) ion with this ligand undergoes hydrolytic cleavage to form ethylenediamine copper(II) complex and the corresponding aldehyde. The antimicrobial results indicate that the chloro complexes exhibit more activity than the acetato complexes. The complexes bind to CT-DNA by intercalation modes. Novel chloroform soluble ZnL 2Cl 2 complex exhibits tremendous antimicrobial, DNA binding and cleaving properties.

  7. Palladium(II) and zinc(II) complexes of neutral [N2O2] donor Schiff bases derived from furfuraldehyde: synthesis, characterization, fluorescence and corrosion inhibitors of ligands.

    PubMed

    Ali, Omyma A M

    2014-11-11

    Metal complexes of Schiff bases derived from furfuraldehyde and 4,5-dimethyl-1,2-phenylendiamine (L1) or 4,5-dichloro-1,2-phenylendiamine (L2) have been reported and characterized based on elemental analyses, IR, 1H NMR, UV-Vis, magnetic moment, molar conductance and thermal analysis. The complexes are found to have the formulae [PdL1-2]Cl2 and [ZnL1-2](AcO)2·H2O. The molar conductance data reveal that Pd(II) and Zn(II) chelates are ionic in nature and are of the type 2:1 electrolytes. The spectral data are consistent with a square planar and tetrahedral geometry around Pd(II) and Zn(II), respectively, in which the ligands act as tetradentate ligands. The thermal behavior of some chelates is studied and the activation thermodynamic parameters are calculated using Coats-Redfern method. The corrosion inhibition of stainless steel types 410 and 304 in 1 M HCl using the synthesized Schiff bases as inhibitors have been studied by weight loss method. The obtained data considered these ligands as efficient corrosion inhibitors. The ligands and their metal complexes exhibited considerable antibacterial activity against Staphylococcusaureus, and Escherichiacoli and antifungal activity against Candida albicans. PMID:24858346

  8. Palladium(II) and zinc(II) complexes of neutral [N2O2] donor Schiff bases derived from furfuraldehyde: Synthesis, characterization, fluorescence and corrosion inhibitors of ligands

    NASA Astrophysics Data System (ADS)

    Ali, Omyma A. M.

    2014-11-01

    Metal complexes of Schiff bases derived from furfuraldehyde and 4,5-dimethyl-1,2-phenylendiamine (L1) or 4,5-dichloro-1,2-phenylendiamine (L2) have been reported and characterized based on elemental analyses, IR, 1H NMR, UV-Vis, magnetic moment, molar conductance and thermal analysis. The complexes are found to have the formulae [PdL1-2]Cl2 and [ZnL1-2](AcO)2·H2O. The molar conductance data reveal that Pd(II) and Zn(II) chelates are ionic in nature and are of the type 2:1 electrolytes. The spectral data are consistent with a square planar and tetrahedral geometry around Pd(II) and Zn(II), respectively, in which the ligands act as tetradentate ligands. The thermal behavior of some chelates is studied and the activation thermodynamic parameters are calculated using Coats-Redfern method. The corrosion inhibition of stainless steel types 410 and 304 in 1 M HCl using the synthesized Schiff bases as inhibitors have been studied by weight loss method. The obtained data considered these ligands as efficient corrosion inhibitors. The ligands and their metal complexes exhibited considerable antibacterial activity against Staphylococcusaureus, and Escherichiacoli and antifungal activity against Candida albicans.

  9. Synthesis, structural and biochemical activity studies of a new hexadentate Schiff base ligand and its Cu(II), Ni(II), and Co(II) complexes

    NASA Astrophysics Data System (ADS)

    Ekmekcioglu, Pinar; Karabocek, Nevin; Karabocek, Serdar; Emirik, Mustafa

    2015-11-01

    A new Schiff base ligand (H2L) and its metal complexes have been prepared and characterized by elemental analysis, magnetic moment and spectral studies. The comparative in-vitro antimicrobial activities against various pathogens with reference to known antibiotics activity under the standard control of different concentrations revealed that the metal complexes (6-8) showed enhanced antimicrobial activities in general as compared to free ligand. As an exception, the free ligand showed better activity against Trichoderma. The antifungal activity experiments were performed in triplicate. The order of biochemical activity for metal complexes were observed as in the following. CuL > CoL > NiL, which is exactly same as the order of stability constants of these complexes. Additionally, we performed DFT and TD-DFT calculation for free ligand and Cu(II) complex to support the experimental data. The geometries of the Cu(II) complex have been optimized using the B3LYP level of theory. The theoretical calculations confirm that the copper (II) center exhibits a distorted square pyramidal geometry which is favored by experimental results.

  10. Mixed ligand complexes of Cu(II)-2-(2-pyridyl)-benzimidazole and aliphatic or aromatic dicarboxylic acids: Synthesis, characterization and biological activity

    NASA Astrophysics Data System (ADS)

    El-Sherif, Ahmed A.; Jeragh, Bakir J. A.

    2007-11-01

    The synthesis and structural characterization of mixed ligand complexes derived from 2-(2-pyridyl)-benzimidazole (PBI) (1ry ligand) and aliphatic or aromatic dicarboxylic acids (2ry ligand) are reported. Cu(II) complexes were characterized on the bases of their elemental analyses, IR, ESR and thermal analyses. The elemental analysis indicated the formation of mixed ligand complexes in a mole ratio 1:1:1 (Cu:L 1:L 2), L 1 = PBI and L 2 = oxalic acid, phthalic acid or malonic acid. IR spectra showed that PBI acts as a neutral bidentate coordinated to the Cu(II) via the pyridyl and imidazolyl nitrogen atoms. The dicarboxylic acids are bidentate with monodentate carboxylate groups. Thermal decomposition study of complexes was monitored by thermogravimetric (TG) and derivative thermogravimetric (DTG) analysis in N 2 atmosphere. The decomposition course and steps were analysed and the activation parameters of the nonisothermal decomposition were calculated from the TG curves and discussed. The isolated metal chelates were screened for their antimicrobial activities and the results are reported, discussed and compared with some known antibiotics.

  11. Exploring the scope of a novel ligand class: synthesis and catalytic examination of metal complexes with 'normal' 1,2,3-triazolylidene ligands.

    PubMed

    Schaper, Lars-Arne; Graser, Lilian; Wei, Xuhui; Zhong, Rui; Öfele, Karl; Pöthig, Alexander; Cokoja, Mirza; Bechlars, Bettina; Herrmann, Wolfgang A; Kühn, Fritz E

    2013-05-20

    Using new 'normal'-substituted 1,2,3-triazolylidene silver compounds as starting materials allowed for preparation of a series of molybdenum, ruthenium, rhodium, and palladium transition metal complexes bound to the new 1,2,3-triazolylidene ligand system. In this work, the first triazolylidene Mo compound is presented as well as the first structural investigation of a silver complex with a monodentate 1,2,3-triazolylidene. Furthermore, the triazolylidene Pd complex and the Mo complex were tested as precatalysts in Suzuki-Miyaura coupling and epoxidation catalysis, respectively. PMID:23646929

  12. Solid-Phase Synthesis as a Platform for the Discovery of New Ruthenium Complexes for Efficient Release of Photocaged Ligands with Visible Light

    PubMed Central

    Sharma, Rajgopal; Knoll, Jessica D.; Ancona, Nicholas; Martin, Phillip D.; Turro, Claudia; Kodanko, Jeremy J.

    2015-01-01

    Ruthenium-based photocaging groups have important applications as biological tools and show great potential as therapeutics. A method was developed to rapidly synthesize, screen and identify ruthenium-based caging groups that release nitriles upon irradiation with visible light. A diverse library of tetra- and pentadentate ligands was synthesized on polystyrene resin. Ruthenium complexes of the general formula [Ru(L)(MeCN)n]m+ (n = 1–3, m = 1–2) were generated from these ligands on solid phase, then cleaved from resin for photochemical analysis. Data indicate a wide range of spectral tuning and reactivity with visible light. Three complexes that showed strong absorbance in the visible range were synthesized by solution phase for comparison. Photochemical behavior of solution- and solid-phase complexes was in good agreement, confirming that the library approach is useful in identifying candidates with desired photoreactivity in short order, avoiding time consuming chromatography and compound purification. PMID:25611351

  13. Complexation of nitrogen and sulphur donor Schiff's base ligand to Cr(III) and Ni(II) metal ions: Synthesis, spectroscopic and antipathogenic studies

    NASA Astrophysics Data System (ADS)

    Sharma, Amit Kumar; Chandra, Sulekh

    2011-01-01

    2,6-Diacetyl pyridine based ligand was synthesized by the reaction of 2,6-diacetyl pyridine with thiocarbohydrazide in presence of acetic acid. The coordination compounds with Cr(III) and Ni(II) metal ions having [Cr(L)X]X 2 and [Ni(L)X]X compositions (where L = ligand and X = NO 3-, Cl - and CH 3COO -) were synthesized and characterized by physicochemical and spectral studies. The studies like elemental analyses, molar conductance measurements, magnetic susceptibility measurements, IR, UV-Vis, NMR, mass and EPR reveal that the complexes are octahedral. The compounds were examined against the pathogenic fungal and bacterial strains like Alternaria brassicae, Aspergillus niger, Fusarium oxysporum, Xanthomonas compestris and Pseudomonas aeruginosa. A. niger causes the diseases Apergillosis and Otomycosis in humans.

  14. Synthesis, crystal structure, antioxidant activity, and DNA-binding studies of a novel Ni(II) [2x2] grid complex with a rigid bistridentate Schiff base ligand.

    PubMed

    Jia, Lei; Xu, Jun; Xu, Xi-Ming; Chen, Long-Hai; Jiang, Peng; Cheng, Fei-Xiang; Lu, Guang-Nong; Wang, Qin; Wu, Jin-Cai; Tang, Ning

    2010-08-01

    With a bistridentate Schiff-base ligand, N',N'(3)-bis[(1E)-1-(2-pyridinyl)ethylidene)] isophthalohydrazide (H(2)L), a [2x2]G grid complex, [Ni(4)(HL)(4)](ClO(4))(4).4H(2)O.0.5 CH(3)OH (1) has been synthesized and characterized spectroscopically and crystallographically. Spectrometric titrations, ethidium bromide displacement experiments, circular dichroism spectral analysis and viscosity measurements indicate that the compound 1 strongly binds with calf-thymus DNA, presumably via intercalation mechanism. Furthermore, the antioxidant activity (superoxide and hydroxyl radical) of the ligand and its nickel(II) complex is determined by using spectrophotometer methods in vitro. Complex 1 is found to possess potent antioxidant activity and be better than standard antioxidants like mannitol. PMID:20686262

  15. Synthesis, structural characterization and DFT calculation on a square-planar Ni(II) complex of a compartmental Schiff base ligand

    NASA Astrophysics Data System (ADS)

    Biswas, Surajit; Dolai, Malay; Dutta, Arpan; Ali, Mahammad

    2016-12-01

    Reaction of a symmetric compartmental Schiff-base ligand, (H2L) with nickel(II) perchlorate hexahydrate in 1:1 M ratio in methanol gives rise to a mononuclear nickel(II) compound, NiL (1). The compound has been characterized by C, H, N microanalyses and UV-Vis spectra. The single crystal X-ray diffraction studies reveal a square planar geometry around the Ni(II) center. The compound crystallizes in monoclinic system with space group C2/c with a = 21.6425(6), b = 9.9481(3), c = 13.1958(4) Å, β = 107.728(2)°, V = 2706.16(14) Å3 and Z = 4. Ground state DFT optimization and TDDFT calculations on the ligand and complex were performed to get their UV-Vis spectral pattern.

  16. Half-sandwich nickel complexes with ring-expanded NHC ligands - synthesis, structure and catalytic activity in Kumada-Tamao-Corriu coupling.

    PubMed

    Banach, Ł; Guńka, P A; Buchowicz, W

    2016-06-01

    The general synthesis of [Ni(Cp)(X)(NHC)] complexes from a nickel halide, CpLi, and a carbene solution is reported. This procedure yields unprecedented complexes with ring-expanded NHC ligands (RE-NHC) of six- (1a, 1b), seven- (1c), and eight-membered (1d) heterocycles. The NMR spectra of 1a-1d are consistent with the hindered rotation of Ni-Ccarbene and N-CMes bonds, while X-ray analyses of 1b, 1c, and 1d reveal a pronounced trans influence of the RE-NHC ligands. Complexes 1a-1e are efficient pre-catalysts in Kumada-Tamao-Corriu coupling with the maximum efficiency observed for complexes bearing the six-membered NHC. PMID:26853761

  17. Synthesis and characterisation of cobalt, nickel and copper complexes with tripodal 4N ligands as novel catalysts for the homogeneous partial oxidation of alkanes

    PubMed Central

    Tordin, Elisa; List, Manuela; Monkowius, Uwe; Schindler, Siegfried; Knör, Günther

    2013-01-01

    Four new compounds of the general formula [M(L)(CH3COO)][PF6], where L is a tetradentate tripodal ligand such as tris[2-(dimethylamino)ethyl]amine (L1) or (2-aminoethyl)bis(2-pyridylmethyl)amine (L2) and M is Co(II), Ni(II) or Cu(II), have been prepared employing a simple two-step synthesis. The compounds have been characterised by elemental analysis, mass spectroscopy, IR spectroscopy and X-ray diffraction. The catalytic properties of the derivatives containing the aliphatic ligand L1 have been investigated in particular toward the oxidation of cyclohexane and adamantane in the presence of the sacrificial oxidant m-CPBA (meta-chloroperbenzoic acid). Good TONs and selectivity have been determined for the cobalt and nickel compounds. PMID:23805005

  18. Synthesis and spectral studies of platinum metal complexes of benzoin thiosemicarbazone

    NASA Astrophysics Data System (ADS)

    Offiong, Offiong E.

    1994-11-01

    The platinum metal chelates of benzoin thiosemicarbazone obtained with Ru(III), Rh(III), Ir(III), Pd(II) and Pt(II) were prepared from their corresponding halide salts. The complexes were characterized by elemental analysis, conductance measurement, IR, Raman, 1H-NMR, 13C-NMR and UV-visible spectra studies. Various ligand field parameters and nephelauxetic parameters were also calculated. The mode of bonding and the geometry of the ligand environment around the metal ion have been discussed in the light of the available data obtained. Complexes of Ru(III), Rh(III) and Ir(III) are six-coordinate octahedral, while Pd(II) and Pt(II) halide complexes are four-coordinated with halides bridging.

  19. Platinum and palladium complexes of thiosemicarbazones derived of 2-acetylthiophene: Synthesis and spectral studies

    NASA Astrophysics Data System (ADS)

    Neto, J. L.; de Lima, G. M.; Beraldo, H.

    2006-03-01

    The reaction of 2-acetylthiophene thiosemicarbazone (2-HATT) and 2-acetylthiophene 4-phenylthiosemicarbazone (2-HAT-4-FT) with Pd(COD)Cl 2 (COD = 1,5-cyclooctadiene) and trans-Pt 2PEt 3Cl 4 yielded four new metal complexes: [Pd(2-HATT)Cl 2] ( 1), [Pd(2-ATT) 2] ( 2), [Pd(2-AT-4-FT)Cl] ( 3) and [Pt(2-ATT)(PEt 3)Cl] ( 4). Apart from compound 3 all the others were characterised by 1H and 13C{ 1H} NMR, infrared spectroscopy, and elemental analysis. Multinuclear NMR experiments of 31P{ 1H} and 195Pt{ 1H} of complex 4 have revealed that the ligand 2-HATT behaves as a bidentate chelating agent towards Pd(COD)Cl 2 and trans-Pt 2PEt 3Cl 4 whereas ligand 2-HAT-4-FT forms a tridentate chelating complex with Pd(COD)Cl 2.

  20. Synthesis, spectroscopic, coordination and biological activities of some organometallic complexes derived from thio-Schiff base ligands

    PubMed Central

    Abou-Hussein, Azza A.; Linert, Wolfgang

    2014-01-01

    Two series of mono- and binuclear complexes cyclic or acyclic thio-ferocine Schiff base ligands, derived from the condensation of 2-aminobenzenthiol (L) with monoacetyl ferrocene in the molar ratio 1:1 or in the molar ratio 1:2 for diacetyl ferocine have been prepared. The condensation reactions yield the corresponding Schiff Base ligands, HLa-Maf and H2Lb-Daf. The chelation of the ligands to metal ions occurs through the sulfur of the thiol group as well as the nitrogen atoms of the azomethine group of the ligands. HLa-Maf acts as monobasic bidentate or dibasic tetradentate, while H2Lb-Daf behaves as twice negatively cargend tetradentate ligand. The structures of these ligands were elucidated by elemental analysis, infrared, ultraviolet–visible spectra, as well as 1H NMR spectra. Reactions of the Schiff bases ligands with ruthenium(III), oxovanadium(IV) and dioxouranium(VI) afforded the corresponding transition metal complexes. The properties of the newly prepared complexes were analyse by elemental analyses, infrared, electronic spectra, 1H NMR as well as the magnetic susceptibility and conductivity measurement. The metal complexes exhibits different geometrical arrangements such as octahedral and square pyramidal coordination. Schiff base ligands and their metal complexes were tested against two pathogenic bacteria as Gram-positive and Gram-negative bacteria as well as one kind of fungi to study their biological activity. All the complexes exhibit antibacterial and antifungal activities against these organisms. PMID:24070648

  1. Synthesis, spectroscopic, coordination and biological activities of some organometallic complexes derived from thio-Schiff base ligands

    NASA Astrophysics Data System (ADS)

    Abou-Hussein, Azza A.; Linert, Wolfgang

    2014-01-01

    Two series of mono- and binuclear complexes cyclic or acyclic thio-ferocine Schiff base ligands, derived from the condensation of 2-aminobenzenthiol (L) with monoacetyl ferrocene in the molar ratio 1:1 or in the molar ratio 1:2 for diacetyl ferocine have been prepared. The condensation reactions yield the corresponding Schiff Base ligands, HLa-Maf and H2Lb-Daf. The chelation of the ligands to metal ions occurs through the sulfur of the thiol group as well as the nitrogen atoms of the azomethine group of the ligands. HLa-Maf acts as monobasic bidentate or dibasic tetradentate, while H2Lb-Daf behaves as twice negatively cargend tetradentate ligand. The structures of these ligands were elucidated by elemental analysis, infrared, ultraviolet-visible spectra, as well as 1H NMR spectra. Reactions of the Schiff bases ligands with ruthenium(III), oxovanadium(IV) and dioxouranium(VI) afforded the corresponding transition metal complexes. The properties of the newly prepared complexes were analyse by elemental analyses, infrared, electronic spectra, 1H NMR as well as the magnetic susceptibility and conductivity measurement. The metal complexes exhibits different geometrical arrangements such as octahedral and square pyramidal coordination. Schiff base ligands and their metal complexes were tested against two pathogenic bacteria as Gram-positive and Gram-negative bacteria as well as one kind of fungi to study their biological activity. All the complexes exhibit antibacterial and antifungal activities against these organisms.

  2. Organotin(IV) complexes of thiohydrazides and thiodiamines: synthesis, spectral and thermal studies

    NASA Astrophysics Data System (ADS)

    Singh, Rajeev; Kaushik, N. K.

    2006-11-01

    Organotin(IV) complexes of tribenzyltin(IV) chloride and di( para-chlorobenzyl)tin(IV) dichloride with thiohydrazides have been reported. The ligands synthesized were bidentate coordinating through sulphur and terminal nitrogen atoms. These form 1:1 metal-ligand complexes. The following organotin(IV) complexes have been synthesized: (C 6H 5CH 2) 3Sn(L 1)Cl, ( p-ClC 6H 4CH 2) 2Sn(L 1)Cl 2, (C 6H 5CH 2) 3Sn(L 1)Cl, ( p-ClC 6H 4CH 2) 2Sn(L 2)Cl 2, (C 6H 5CH 2) 3Sn(L 3)Cl, ( p-ClC 6H 4CH 2) 2Sn(L 3)Cl 2, where (L 1): 2-phenylethyl N-thiohydrazide, (L 2): N-(2-phenylethyl- N-thio)-1,3-propane diamine, (L 3): N-(2-phenylethyl- N-thio)-1,2-ethane diamine. The complexes were synthesized by directly mixing, refluxing and stirring the ligands with organotin(IV) chlorides in a suitable solvent. The complexes were found to be pure and were characterized by elemental analysis, electronic, infrared, 1H and 13C NMR spectroscopy. These complexes were also studied for their thermal decomposition by thermogravimetry (TG) and differential thermal analysis (DTA). Various kinetic and thermodynamic parameters, viz. activation energy ( Ea), order of reaction ( n), apparent activation entropy ( S#) and heat of reaction (Δ H) have been determined by using Horowitz-Metzger method. It was observed that these complexes are highly stable and the thermal degradation of these complexes is a spontaneous process. The ligands and their tin complexes have also been screened for their fungitoxicity activity and found to be quite active in this respect.

  3. Synthesis and spectral and redox properties of three triply bridged complexes of ruthenium

    USGS Publications Warehouse

    Llobet, A.; Curry, M.E.; Evans, H.T.; Meyer, T.J.

    1989-01-01

    Syntheses are described for the ligand-bridged complexes [(tpm)RuIII(??-O)(??-L)2RuIII(tpm) n+ (L = O2P(O)(OH), n = 0 (1); L = O2CO, n = 0 (2); L = O2CCH3, n = 2 (3); tpm is the tridentate, facial ligand tris(1-pyrazolyl)methane. The X-ray crystal structure of [(tpm)Ru(??-O)(??-O2P(O)(OH))2Ru(tpm)]??8H 2O was determined from three-dimensional X-ray counter data. The complex crystallizes in the trigonal space group P3221 with three molecules in a cell of dimensions a = 18.759 (4) A?? and c = 9.970 (6) A??. The structure was refined to a weighted R factor of 0.042 based on 1480 independent reflections with I ??? 3??(I). The structure reveals that the complex consists of two six-coordinate ruthenium atoms that are joined by a ??-oxo bridge (rRU-O = 1.87 A??; ???RuORu = 124.6??) and two ??-hydrogen phosphato bridges (average rRu-O = 2.07 A??) which are capped by two tpm ligands. The results of cyclic voltammetric and coulometric experiments show that the complexes undergo both oxidative and reductive processes in solution. Upon reduction, the ligand-bridged structure is lost and the monomer [(tpm)Ru(H2O)3]2+ appears quantitatively. All three complexes are diamagnetic in solution. The diamagnetism is a consequence of strong electronic coupling between the low-spin d5 Ru(III) metal ions through the oxo bridge and the relatively small Ru-O-Ru angle. ?? 1989 American Chemical Society.

  4. Mono, bi- and trinuclear metal complexes derived from new benzene-1,4-bis(3-pyridin-2-ylurea) ligand. Spectral, magnetic, thermal and 3D molecular modeling studies

    NASA Astrophysics Data System (ADS)

    El-ghamry, Mosad A.; Saleh, Akila A.; Khalil, Saied M. E.; Mohammed, Amira A.

    2013-06-01

    New bis (pyridylurea) ligand, H2L, was synthesized by the reaction of ethylpyridine-2-carbamate (EPC) and p-phenylenediamine. The ligand was characterized by elemental analysis, IR, 1H NMR, electronic and mass spectra. Reaction of the prepared ligand with Co2+, Ni2+, Cu2+, Fe3+, VO2+ and UO22+ ions afforded mono, bi- and trinuclear metal complexes. Also, new mixed ligand complexes of the ligand H2L and 8-hydroxyquinoline (8-HQ) with Co2+, Ni2+, Cu2+ and Fe3+ ions were synthesized. The ligand behaves as bi- and tetradentate toward the transition metal ions, coordination via the pyridine sbnd N, the carbonyl sbnd O and/or the amidic sbnd N atoms in a non, mono- and bis-deprotonated form. The complexes were characterized by elemental and thermal analyses, IR, electronic and mass spectra as well as conductance and magnetic susceptibility measurements. The results showed that the metal complexes exhibited different geometrical arrangements such as square planar, tetrahedral, octahedral and square pyramidal arrangements. The Coats-Redfern equation was used to calculate the kinetic and thermodynamic parameters for the different thermal decomposition steps of some complexes. 3D molecular modeling of the ligand, H2L and a representative complex were studied.

  5. Synthesis, spectral characterization and biological evaluation of Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes with thiosemicarbazone ending by pyrazole and pyridyl rings

    NASA Astrophysics Data System (ADS)

    Yousef, T. A.; Abu El-Reash, G. M.; Al-Jahdali, M.; El-Rakhawy, El-Bastawesy R.

    2014-08-01

    Here we present the synthesis of the new Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes with chelating ligand (Z)-(2-((1,3-diphenyl-1H-pyrazol-4-yl)methylene) hydrazinyl)(pyridin-2-ylamino)methanethiol. All the complexes were characterized by elemental analysis, IR, 1H NMR, UV-vis, magnetic susceptibility measurements and EPR spectral studies. IR spectra of complexes showed that the ligand behaves as NN neutral bidentate, NSN mononegative tridentate and NSNN mononegative tetradentate. The electronic spectra and the magnetic measurements suggested the octahedral geometry for all complexes as well as the EPR confirmed the tetragonal distorted octahedral for Cu(II) complex. Cd(II) complex showed the highest inhibitory antioxidant activity either using ABTS method. The SOD-like activity exhibited those Cd(II) and Zn(II) complexes have strong antioxidative properties. We tested the synthesized compounds for antitumor activity and showed that the ability to kill liver (HePG2) and breast (MCF-7) cancer cells definitely.

  6. Synthesis, spectral characterization and biological evaluation of Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes with thiosemicarbazone ending by pyrazole and pyridyl rings.

    PubMed

    Yousef, T A; Abu El-Reash, G M; Al-Jahdali, M; El-Rakhawy, El-Bastawesy R

    2014-08-14

    Here we present the synthesis of the new Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes with chelating ligand (Z)-(2-((1,3-diphenyl-1H-pyrazol-4-yl)methylene) hydrazinyl)(pyridin-2-ylamino)methanethiol. All the complexes were characterized by elemental analysis, IR, (1)H NMR, UV-vis, magnetic susceptibility measurements and EPR spectral studies. IR spectra of complexes showed that the ligand behaves as NN neutral bidentate, NSN mononegative tridentate and NSNN mononegative tetradentate. The electronic spectra and the magnetic measurements suggested the octahedral geometry for all complexes as well as the EPR confirmed the tetragonal distorted octahedral for Cu(II) complex. Cd(II) complex showed the highest inhibitory antioxidant activity either using ABTS method. The SOD-like activity exhibited those Cd(II) and Zn(II) complexes have strong antioxidative properties. We tested the synthesized compounds for antitumor activity and showed that the ability to kill liver (HePG2) and breast (MCF-7) cancer cells definitely. PMID:24727176

  7. Ni(II) and Pd(II) complexes with new N,O donor thiophene appended Schiff base ligand: Synthesis, electrochemistry, X-ray structure and DFT calculation

    NASA Astrophysics Data System (ADS)

    Kundu, Subhankar; Pramanik, Ajoy Kumar; Mondal, Apurba Sau; Mondal, Tapan Kumar

    2016-07-01

    The thiophene appended Schiff's base ligand, 1-(2-(thiophen-2-yl)ethylimino)methyl)naphthalene-2-ol (HL) with N,O donor sites has been synthesized by the condensation between 2-hydroxy-1-naphthaldehyde and thiophene-2-ethylamine. The square planar 1:2 complexes of HL having general formula [M(L)2] (M = Ni(1) and Pd(2)) with nickel(II) and palladium(II) have been synthesized and characterized by several spectroscopic techniques. The geometry has been confirmed by single crystal X-ray study for complex 1. The electronic structure and spectral properties of the complexes are interpreted by DFT and TDDFT studies.

  8. New mixed ligand zinc(II) complexes based on the antiepileptic drug sodium valproate and bioactive nitrogen-donor ligands. Synthesis, structure and biological properties.

    PubMed

    Darawsheh, Mohanad; Abu Ali, Hijazi; Abuhijleh, A Latif; Rappocciolo, Emilia; Akkawi, Mutaz; Jaber, Suhair; Maloul, Salam; Hussein, Yasmeen

    2014-07-23

    Starting from the precursor [Zinc Valproate complex] (1), new mixed ligand zinc(II) complexes of valproic acid and nitrogen-based ligands, formulating as, [Zn(valp)22,9-dmphen] (2), [Zn2(valp)4(quin)2] (3), [Zn(valp)2(2-ampy)2] (4), and [Zn(valp)2(2-ampic)2] (5) (valp = valproate, 2,9-dmphen = 2,9-dimethyl-1,10-phenanthroline, quin = quinoline, 2-ampy = 2-aminopyridine, 2-ampic = 2-amino-6-picoline) were synthesized and characterized using IR, (1)H NMR, (13)C{(1)H} NMR and UV-Vis spectrometry. The crystal structures of complexes 2, 3 and 4 were determined using single-crystal X-ray diffraction. The complexes were also evaluated for their anti-bacterial activity using in-vitro agar diffusion method against three Gram-positive (Micrococcus luteus, Staphylococcus aureus, and Bacillus subtilis) and three Gram-negative (Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis) species. Complex 2 showed considerable activity against all tested microorganisms and the effect of complexation on the anti-bacterial activity of the parent ligand of 2 was also investigated. The anti-bacterial activity of 2,9-dmphen against Gram-negative bacteria was enhanced upon complexation with zinc valproate. On the other hand, complexes 1 and 3 showed weak inhibition activity against the tested species and complexes 4 and 5 didn't show any activity at all. Two methods were used for testing the inhibition of ferriprotoporphyrinIX bio-mineralization: a semi-quantitative micro-assay and a previously self-developed quantitative in-vitro method. Both were used to study the efficiency of these complexes in inhibiting the formation of the Malaria pigment which considered being the target of many known anti-malarial drugs such as Chloroquine and Amodiaquine. Results showed that the efficiency of complex 2 in preventing the formation of β-Hematin was 80%. The efficiency of Amodiaquine as a standard drug was reported to give 91%. PMID:24904962

  9. Synthesis, growth, spectral and thermal properties of a new organic crystal: 2-Carboxypyridin-1-ium trichloroacetate

    NASA Astrophysics Data System (ADS)

    Gowri, S.; Anitha, K.; Suresh, A.; Uma Devi, T.; Selvanayagam, S.; Sajan, D.; Chandramohan, A.; Lawrence, N.

    2012-09-01

    A novel organic optical material complex of 2-carboxypyridin-1-ium trichloroacetate has been synthesized and crystals were grown from aqueous solution employing the technique of controlled evaporation. The crystal structure has been determined using single crystal X-ray diffraction studies. The single crystals were successfully grown by the slow evaporation method with dimensions 12 × 8 × 3 mm3. FT IR spectral investigation has been carried out to identify the various functional groups present in the grown crystal. Molecular structure was confirmed by NMR spectral analysis. Melting point was found using thermal measurements.

  10. Synthesis, growth, spectral and thermal properties of a new organic crystal: 2-carboxypyridin-1-ium trichloroacetate.

    PubMed

    Gowri, S; Anitha, K; Suresh, A; Uma Devi, T; Selvanayagam, S; Sajan, D; Chandramohan, A; Lawrence, N

    2012-09-01

    A novel organic optical material complex of 2-carboxypyridin-1-ium trichloroacetate has been synthesized and crystals were grown from aqueous solution employing the technique of controlled evaporation. The crystal structure has been determined using single crystal X-ray diffraction studies. The single crystals were successfully grown by the slow evaporation method with dimensions 12 × 8 × 3 mm(3). FT IR spectral investigation has been carried out to identify the various functional groups present in the grown crystal. Molecular structure was confirmed by NMR spectral analysis. Melting point was found using thermal measurements. PMID:22613126

  11. Copper(I)/Ligand-Catalyzed 5-endo Radical Cyclization-Aromatization of 2,2,2-Trichloroethyl Vinyl Ethers: Synthesis of 2,3-Difunctionalized 4-Chlorofurans.

    PubMed

    Ram, Ram N; Gupta, Dharmendra Kumar; Soni, Vineet Kumar

    2016-02-19

    Copper(I)/ligand-catalyzed one pot synthesis of highly substituted 2,3-difunctionalized-4-chlorofurans has been reported. The reaction proceeds via a Cu(I)-catalyzed regioselective 5-endo-trig radical cyclization of 2,2,2-trichloroethyl vinyl ethers followed by the base-promoted dehydrochlorination. The success of the kinetically disfavored 5-endo cyclization was attributed to the formation of captodatively stabilized radical intermediate in the cyclization step and relatively high reaction temperature. Synthetic application of this protocol was also demonstrated in the preparation of alkyl and aryl substituted 4-chlorofuranonapthoquinones. PMID:26796068

  12. Ligand-free Cu-catalyzed [3 + 2] cyclization for the synthesis of pyrrolo[1,2-a]quinolines with ambient air as a terminal oxidant.

    PubMed

    Yu, Yang; Liu, Yuan; Liu, Aoxia; Xie, Hexin; Li, Hao; Wang, Wei

    2016-08-21

    A ligand-free Cu-catalyzed [3 + 2] cycloaddition of ethyl 2-(quinolin-2-yl)acetates, ethyl 2-(isoquinolin-1-yl)acetates, and ethyl 2-(pyridin-2-yl)acetates with (E)-chalcones for a "one-pot" synthesis of pyrrolo[1,2-a]quinolines, pyrrolo[2,1-a]isoquinolines and indolizines has been developed. The annulation products were isolated in moderate to good yields with air as the sole oxidant under mild conditions. PMID:27452813

  13. Synthesis, characterization and biological relevance of some metal (II) complexes with oxygen, nitrogen and oxygen (ONO) donor Schiff base ligand derived from thiazole and 2-hydroxy-1-naphthaldehyde

    NASA Astrophysics Data System (ADS)

    Nagesh, G. Y.; Mruthyunjayaswamy, B. H. M.

    2015-04-01

    The novel Schiff base ligand 2-((2-hydroxynaphthalen-1-yl)methylene)-N-(4-phenylthiazol-2-yl)hydrazinecarboxamide (L) obtained by the condensation of N-(4-phenylthiazol-2-yl)hydrazinecarboxamide with 2-hydroxy-1-naphthaldehyde and its newly synthesized Cu(II), Co(II), Ni(II), Zn(II) and Cd(II) complexes have been characterized by microanalysis, molar conductance, IR, 1H NMR, ESI-mass, UV-Visible, TGA/DTA, ESR and powder X-ray diffraction data to explicate their structures. The IR results confirmed the tridentate binding of the ligand involving oxygen atom of amide carbonyl, azomethine nitrogen and naphthol oxygen. 1H NMR spectral data of the ligand (L) and its Zn(II) complex agreed well with the proposed structures. Thermogravimetric studies for Cu(II) and Ni(II) complexes indicated the presence of coordinated water molecules and the final product is the metal oxide. In order to appraise the effect of antimicrobial activity of metal ions upon chelation, the newly synthesized ligand and its metal complexes were screened for their antimicrobial activity by minimum inhibitory concentration (MIC) method. The DNA cleavage activities were studied using plasmid DNA pBR322 (Bangal re Genei, Bengaluru, Cat. No 105850) as a target molecule by agarose gel electrophoresis method. The brine shrimp bioassay was also carried out to study the in vitro cytotoxicity properties against Artemia salina. Furthermore, the antioxidant activity were determined in vitro by reduction of 1,1-diphenyl-2-picryl hydrazyl (DPPH). The ligand exhibited better in vitro-antioxidant activity than its metal complexes.

  14. Synthesis, spectroscopic characterization, electrochemistry and biological evaluation of some metal (II) complexes with ONO donor ligand containing benzo[b]thiophene and coumarin moieties

    NASA Astrophysics Data System (ADS)

    Mahendra Raj, K.; Mruthyunjayaswamy, B. H. M.

    2014-09-01

    Schiff base ligand 3-chloro-N‧-((7-hydroxy-4-methyl-2-oxo-2H-chromen-8-yl)methylene)benzo[b]thiophene-2-carbohydrazide and its Cu(II), Co(II), Ni(II) and Zn(II) complexes were synthesized, characterized by elemental analysis and various physico-chemical techniques like, IR, 1H NMR, ESI-mass, UV-Visible, thermogravimetry - differential thermal analysis, magnetic measurements and molar conductance. Spectral analysis indicates octahedral geometry for all the complexes. Cu(II) complex have 1:1 stoichiometry of the type [M(L)(Cl)(H2O)2], whereas Co(II), Ni(II) and Zn(II) complexes have 1:2 stoichiometric ratio of the type [M(L)2]. The bonding sites are the oxygen atom of amide carbonyl, nitrogen of azomethine function and phenolic oxygen of the Schiff base ligand via deprotonation. The thermogravimetry - differential thermal analysis studies gave evidence for the presence of coordinated water molecules in the composition of Cu(II) complex which was further supported by IR measurements. All the complexes were investigated for their electrochemical activity, but only the Cu(II) complex showed the redox property. In order to evaluate the effect of antimicrobial potency of metal ions upon chelation, ligand and its metal complexes along with their respective metal chlorides were screened for their antibacterial and antifungal activities by minimum inhibitory concentration (MIC) method. The results showed that the metal complexes were found to be more active than free ligand. Ligand and its complexes were screened for free radical scavenging activity by DPPH method and DNA cleavage activity using Calf-thymus DNA (Cat. No-105850).

  15. Synthesis and structural characterization of zinc(II) and cobalt(II) complexes based on multidentate hydrazone ligands

    NASA Astrophysics Data System (ADS)

    Li, Li; Zhang, Yuan Zhuo; Liu, E.; Yang, Chengxiong; Golen, James A.; Rheingold, Arnold L.; Zhang, Guoqi

    2016-04-01

    Two multidentate Schiff base ligands containing a hydrazone unit have been synthesized and investigated for zinc(II) and cobalt(II) coordination chemistry. The reactions of the 4-pyridyl derived hydrazone ligand HL1 with zinc(II) or cobalt(II) salts gave three mononuclear complexes that were structurally characterized by X-ray diffraction analysis. The results revealed that the ligand could adopt different coordination modes when various counter anions were employed. While in the case that zinc dichloride was used as a metal salt a neutral mononuclear mono-ligand complex was formed, the deprotonation of hydrazone occurred when zinc(II) or cobalt(II) nitrate were present and two new isostructural mononuclear bis-ligand complexes were isolated. Modification of the hydrazone ligand with oxygen donors was found to have a significant impact on the ligand reactivity, and a similar reaction of H2L2 with cobalt(II) nitrate gave a protonated product of H2L2 without the incorporation of cobalt(II), which features a one-dimensional hydrogen-bonded network in the solid state.

  16. Emissive bis-salicylaldiminato Schiff base ligands and their zinc(II) complexes: Synthesis, photophysical properties, mesomorphism and DFT studies

    NASA Astrophysics Data System (ADS)

    Paul, Manoj Kr.; Dilipkumar Singh, Y.; Bedamani Singh, N.; Sarkar, Utpal

    2015-02-01

    Bis-salicylaldiminato Schiff base ligands and their Zn(II) complexes derived from 2,3-Diaminomaleonitrile (DAMN) were synthesized. Their molecular structures, photophysical properties and mesogenic behaviors were investigated. The ligands and their Zn(II) complexes were characterized by using elemental analysis, FT-IR, 1H NMR and molar conductivity measurements. Photophysical properties of ligands and their Zn(II) complexes were investigated in different polar solvents by using UV-visible and fluorescence spectroscopic studies. Ligands emit green light whereas complexes emit orange light upon irradiation with UV-visible light. The liquid crystalline phases of ligands and their Zn(II) complexes were characterized by polarizing optical microscopy and differential scanning calorimetry. The ligand having longer 4-n-octadecyloxy chain (n = 18) displays columnar phase whereas the lower homologues (n = 16, 12) did not show mesophase. The Zn(II) complexes having 4-n-octadecyloxy end chain display smectic B like phase whereas other lower homologues are non mesogenic in nature. The thermal stability of the compounds were studied by using thermo gravimetric analysis. The density functional theory was carried out to obtain the stable molecular conformation, dipole moment, molecular orbitals and polarizability of the ligands and their Zn(II) complexes.

  17. Synthesis, characterization, X-ray structure and photoluminescence properties of two Ce(III) complexes derived from pentadentate ligands

    NASA Astrophysics Data System (ADS)

    Köse, Muhammet; Akgün, Eyup; Ceyhan, Gökhan

    2015-12-01

    In this study, two new Ce(III) complexes [Ce(L1)(NO3)3]•H2O and [Ce(L2)(NO3)3]•H2O were synthesized and characterized by spectroscopic and analytical methods where L1 and L2 are pentadentate diimine ligands. Molecular structure of [Ce(L1)(NO3)3]•H2O was determined by single crystal X-ray diffraction study. The complex was found to crystallize as [Ce(L1)(NO3)3] H2O. In the complex, the ligand L1 coordinates to the Ce(III) ion with the N3O2 donor set and the Ce(III) ion sits within the cavity of acyclic ligand. The Ce(III) ion is 11-coordinated by three nitrogen atoms from the ligand and eight O atoms, six of which come from three nitrate ions, two from the ligand. In the structure of the complex, water molecules link molecules together to form a 3D hydrogen bond network. Thermal behavior of the Schiff base ligands and their Ce(III) complexes metal complexes were studied under nitrogen atmosphere in the temperature range of 20-800 °C. Thermal stability of the ligands increased upon complexation with Ce(III) ion. In the UV-Vis spectra of Ce(III) complexes, new absorption bands appeared at 340-450 nm and these new bands were attributed to metal-ligand (M-L) charge transitions. Photoluminescence properties of the ligands and their Ce(III) complexes were examined.

  18. Spectral synthesis in the ultraviolet. IV - A library of mean stellar groups

    NASA Technical Reports Server (NTRS)

    Fanelli, Michael N.; O'Connell, Robert W.; Burstein, David; Wu, Chi-Chao

    1992-01-01

    A library of mean UV stellar energy distributions is derived from IUE spectrophotometry of 218 stars. The spectra cover 1230-3200 A with a spectral resolution of about 6 A. They have been corrected for interstellar extinction and converted to a common flux and wavelength scale. Individual stars were combined into standard groups according to their continuum colors, observed UV spectral morphology, MK luminosity class, and metal abundance. The library consists of 56 groups: 21 dwarf(V), 8 subgiant(IV), 16 giant(III), and supergiant(I + II) groups, covering O3-M4 spectral types. A metal-poor sequence is included, containing four dwarf and two giant groups, as is a metal-enhanced sequence with a single dwarf, subgiant, and giant group. Spectral indices characterizing the continuum and several strong absorption features are examined as temperature, luminosity, and abundance diagnostics. The library is intended to serve as a basis for interpreting the composite UV spectra of a wide variety of stellar systems, e.g., elliptical galaxies, starburst systems, and high-redshift galaxies.

  19. Benzodiazepine receptor ligands. 8: synthesis and pharmacological evaluation of new pyrazolo[5,1-c] [1,2,4]benzotriazine 5-oxide 3- and 8-disubstituted: high affinity ligands endowed with inverse-agonist pharmacological efficacy.

    PubMed

    Guerrini, Gabriella; Costanzo, Annarella; Ciciani, Giovanna; Bruni, Fabrizio; Selleri, Silvia; Costagli, Camilla; Besnard, François; Costa, Barbara; Martini, Claudia; De Siena, Gaetano; Malmberg-Aiello, Petra

    2006-02-01

    The synthesis and the binding study of new 3-arylesters and 3-heteroarylpyrazolo[5,1-c][1,2,4]benzotriazine 5-oxide 8-substituted are reported. The nature of these substituents (in terms of lipophilic and electronic features) seems to influence the binding affinity. High-affinity ligands were studied in mice in vivo for their pharmacological effects, considering six potential benzodiazepine actions: anxiolytic-like effects, muscle relaxant effects, motor coordination, anticonvulsant action, spontaneous motor activity, and ethanol-potentiating action. Compounds 4d and 6d showed an inverse-agonist profile. These compounds were evaluated also for their binding at benzodiazepine site on GABAA receptor complex (GABAA/BzR complex) subtype to evaluate their subtype selectivity. PMID:16214350

  20. Synthesis, spectral characterization and catalytic activity of Co(II) complexes of drugs: Crystal structure of Co(II)-trimethoprim complex

    NASA Astrophysics Data System (ADS)

    Madhupriya, Selvaraj; Elango, Kuppanagounder P.

    2014-01-01

    New Co(II) complexes with drugs such as trimethoprim (TMP), cimetidine (CTD), niacinamide (NAM) and ofloxacin (OFL) as ligands were synthesized. The complexes were characterized by analytical analysis, various spectral techniques such as FT-IR, UV-Vis, magnetic measurements and molar conductivity. The magnetic susceptibility results coupled with the electronic spectra suggested a tetrahedral geometry for the complexes. The coordination mode of trimethoprim ligand and geometry of the complex were confirmed by single crystal X-ray studies. In this complex the metal ion possesses a tetrahedral geometry with two nitrogen atom from two TMP ligands and two chloride ions coordinated to it. The catalytic activity of the complexes in aryl-aryl coupling reaction was screened and the results indicated that among the four complexes [Co(OFL)Cl(H2O)] exhibited excellent catalytic activity.

  1. Synthesis, spectral characterization, and pharmacological importance of new 4H-1,4-benzothiazines, their sulfone analogues, and ribofuranosides.

    PubMed

    Gautam, Naveen; Garg, Ankita; Gautam, Dinesh Chand

    2015-01-01

    The present article describes the synthesis of new 4H-1,4-benzothiazines via condensation and oxidative cyclization of substituted 2-aminobenzenethiols with compounds containing active methylene groups. It is believed that the reaction proceeds via intermediary of the enaminoketone system. The sulfone derivatives were synthesized by oxidation of 4H-1,4-benzothiazines using 30% hydrogen peroxide in glacial acetic acid. Benzothiazines were used as bases to prepare ribofuranosides by treatment with a sugar derivative (β-D-ribofuranosyl-1-acetate-2,3,5-tribenzoate). The pharmacological importance of the synthesized compounds was evaluated by their, antimicrobial properties against various bacterial strains and fungal species. The structures of the compounds have been confirmed by spectral and chemical analysis. PMID:25513863

  2. Binuclear ruthenium(III) bis(thiosemicarbazone) complexes: synthesis, spectral, electrochemical studies and catalytic oxidation of alcohol.

    PubMed

    Mohamed Subarkhan, M; Ramesh, R

    2015-03-01

    A new series of binuclear ruthenium(III) thiosemicarbazone complexes of general formula [(EPh3)2(X)2Ru-L-Ru(X)2(EPh3)2] (where E=P or As; X=Cl or Br; L=NS chelating bis(thiosemicarbazone ligands) has been synthesized and characterized by analytical and spectral (FT-IR, UV-Vis and EPR). IR spectra show that the thiosemicarbazones behave as monoanionic bidentate ligands coordinating through the azomethine nitrogen and thiolate sulphur. The electronic spectra of the complexes indicate that the presence of d-d and intense LMCT transitions in the visible region. The complexes are paramagnetic (low spin d(5)) in nature and all the complexes show rhombic distortion around the ruthenium ion with three different 'g' values (gx≠gy≠gz) at 77K. All the complexes are redox active and exhibit an irreversible metal centered redox processes (Ru(III)-Ru(III)/Ru(IV)-Ru(IV); Ru(III)-Ru(III)/Ru(II)-Ru(II)) within the potential range of 0.38-0.86V and -0.39 to -0.66 V respectively, versus Ag/AgCl. Further, the catalytic efficiency of one of the complexes [Ru2Cl2(AsPh3)4(L1)] (4) has been investigated in the case of oxidation of primary and secondary alcohols into their corresponding aldehydes and ketones in the presence of N-methylmorpholine-N-oxide(NMO) as co-oxidant. The formation of high valent Ru(V)O species is proposed as catalytic intermediate for the catalytic cycle. PMID:25498823

  3. Binuclear ruthenium(III) bis(thiosemicarbazone) complexes: Synthesis, spectral, electrochemical studies and catalytic oxidation of alcohol

    NASA Astrophysics Data System (ADS)

    Mohamed Subarkhan, M.; Ramesh, R.

    2015-03-01

    A new series of binuclear ruthenium(III) thiosemicarbazone complexes of general formula [(EPh3)2(X)2Ru-L-Ru(X)2(EPh3)2] (where E = P or As; X = Cl or Br; L = NS chelating bis(thiosemicarbazone ligands) has been synthesized and characterized by analytical and spectral (FT-IR, UV-Vis and EPR). IR spectra show that the thiosemicarbazones behave as monoanionic bidentate ligands coordinating through the azomethine nitrogen and thiolate sulphur. The electronic spectra of the complexes indicate that the presence of d-d and intense LMCT transitions in the visible region. The complexes are paramagnetic (low spin d5) in nature and all the complexes show rhombic distortion around the ruthenium ion with three different 'g' values (gx ≠ gy ≠ gz) at 77 K. All the complexes are redox active and exhibit an irreversible metal centered redox processes (RuIII-RuIII/RuIV-RuIV; RuIII-RuIII/RuII-RuII) within the potential range of 0.38-0.86 V and -0.39 to -0.66 V respectively, versus Ag/AgCl. Further, the catalytic efficiency of one of the complexes [Ru2Cl2(AsPh3)4(L1)] (4) has been investigated in the case of oxidation of primary and secondary alcohols into their corresponding aldehydes and ketones in the presence of N-methylmorpholine-N-oxide(NMO) as co-oxidant. The formation of high valent RuVdbnd O species is proposed as catalytic intermediate for the catalytic cycle.

  4. Synthesis and biological activity of small peptides as NOP and opioid receptors' ligands: view on current developments.

    PubMed

    Naydenova, Emilia; Todorov, Petar; Zamfirova, Rositza

    2015-01-01

    The heptadecapeptide nociceptin, also called orphanin FQ (N/OFQ), is the endogenous agonist of the N/OFQ peptide receptor (NOP receptor) and is involved in several central nervous system pathways, such as nociception, reward, tolerance, and feeding. The discovery of small molecule ligands for NOP is being actively pursued for several therapeutic applications. This review presents overview of the several recently reported NOP ligands (agonists and antagonists), with an emphasis of the structural features that may be important for modulating the intrinsic activity of these ligands. In addition, a brief account on the characterization of newly synthesized ligands of NOP receptor with aminophosphonate moiety and β-tryptophan analogues will be presented. PMID:25677770

  5. Synthesis, structure and magnetism of new polynuclear transition metal aggregates assembled with Schiff-base ligand and anionic N-donor ligands

    NASA Astrophysics Data System (ADS)

    Li, Yangguang; Wu, Qiong; Lecren, Lollita; Clérac, Rodolphe

    2008-11-01

    Three new polynuclear aggregates [Co 6(sae) 4(N 3) 6(MeO) 2(MeOH) 2]·0.5H 2O ( 1), [Mn 4O(sae) 4(C(CN) 3)(MeOH) 3](NO 3)·MeOH ( 2) and [NaFe 6(sae) 6(MeO) 6] (N(CN) 2)·H 2O ( 3) have been synthesized with mixed ligands of Schiff-base (salicylidene-2-ethanolamine, H 2sae) and various anionic N-donor ligands (N 3-, N(CN) 2- or C(CN) 3-) and transition metal salts in methanol solution. Crystallographic data for 1: trigonal, R3¯, a = 26.113(4) Å, b = 26.113(4) Å, c = 20.689(4) Å, γ = 120°, V = 12,218(3) Å 3, Z = 9, R1( wR2) = 0.0753(0.2176); for 2: orthorhombic, Pna2 1, a = 20.746(4) Å, b = 13.357(3) Å, c = 17.992(4) Å, V = 4985.6(2) Å 3, Z = 4, R1( wR2) = 0.0357(0.0969); for 3: monoclinic, C2/ c, a = 30.311(6) Å, b = 12.452(3) Å, c = 20.789(4) Å, β = 94.75(3)°, V = 7820(3) Å 3, Z = 4, R1( wR2) = 0.0773(0.2299). Compound 1 exhibits a new rod-like [Co III4Co II2] structural feature. Compound 2 contains an unusual tetranuclear [Mn III4] cationic core. Compound 3 possesses a well-known circle-like [Fe III6] unit encapsulated a central sodium cation. Magnetic properties of these compounds have been studied revealing the presence of (i) intra-molecular antiferromagnetic interactions in 2 and 3 that induce an overall ST = 0 ground state and (ii) Co II-Co II ferromagnetic interactions in complex 1.

  6. Synthesis of novel Schiff base ligands from gluco- and galactochloraloses for the Cu(II) catalyzed asymmetric Henry reaction.

    PubMed

    Alkan, Sevda; Telli, Fatma Ç; Salman, Yeşim; Astley, Stephen T

    2015-04-30

    A series of chiral Schiff base ligands has been prepared using aminochloralose derivatives of glucose and galactose. These ligands were used as catalysts in the asymmetric Henry reaction in the presence of Cu(II) ions giving yields of up to 95%. An interesting solvent dependency on enantiomeric control was observed with the best enantiomeric excesses (up to 91%) being obtained in the presence of water. PMID:25742867

  7. Synthesis, crystal structure and luminescence properties of lanthanide coordination polymers with a new semirigid bridging thenylsalicylamide ligand

    SciTech Connect

    Song, Xue-Qin Wang, Li; Zhao, Meng-Meng; Wang, Xiao-Run; Peng, Yun-Qiao; Cheng, Guo-Quan

    2013-09-15

    Two new lanthanide coordination polymers based on a semirigid bridging thenylsalicylamide ligand ([Ln{sub 2}L{sub 3}(NO{sub 3}){sub 6}]·(C{sub 4}H{sub 8}O{sub 2}){sub 2}){sub ∞} were obtained and characterized by elemental analysis, X-ray diffraction, IR and TGA measurements. The two compounds are isostructure and possess one dimensional trapezoid ladder-like chain built up from the connection of isolated LnO{sub 3}(NO{sub 3}){sub 3} polyhedra (distorted monocapped antisquare prism) through the ligand. The photoluminescence analysis suggest that there is an efficient ligand-to-Ln(III) energy transfer in Tb(III) complex and the ligand is an efficient “antenna” for Tb(III). From a more general perspective, the results demonstrated herein provide the possibility of controlling the formation of the desired lanthanide coordination structure to enrich the crystal engineering strategy and enlarge the arsenal for developing excellent luminescent lanthanide coordination polymers. - Graphical abstract: We present herein one dimensional lanthanide coordination polymers of a new semirigid exo-bidentate ligand which not only display interesting structures but also possess strong luminescence properties. Display Omitted - Highlights: • We present lanthanide coordination polymers of a new semirigid exo-bidentate ligand. • The lanthanide coordination polymers exhibit interesting structures. • The luminescent properties of Tb(III) complexes are discussed in detail.

  8. Synthesis and Evaluation of Conformationally Restricted N4-Tetradentate Ligands for Implementation in An(III)/Ln(III) Separations

    SciTech Connect

    Mark D. Ogden; G. Patrick Meier; Kenneth L. Nash

    2012-01-01

    The previous literature demonstrates that donor atoms softer than oxygen are effective for separating trivalent lanthanides (Ln(III)) from trivalent actinides (An(III)) (Nash, K.L., in: Gschneider, K.A. Jr., et al. (eds.) Handbook on the Physics and Chemistry of Rare Earths, vol. 18-Lanthanides/Actinides Chemistry, pp. 197-238. Elsevier Science, Amsterdam, 1994). It has also been shown that ligands that 'restrict' their donor groups in a favorable geometry, appropriate to the steric demands of the cation, have an increased binding affinity. A series of tetradentate nitrogen containing ligands have been synthesized with increased steric 'limits'. The pK a values for these ligands have been determined using potentiometric titration methods and the formation of the colored copper(II) complex has been used as a method to determine ligand partitioning between the organic and aqueous phases. The results for the 2-methylpyridyl-substituted amine ligands are encouraging, but the results for the 2-methylpyridyl-substituted diimines indicate that these ligands are unsuitable for implementation in a solvent extraction system due to hydrolysis.

  9. Synthesis of Lick Spectral Indices With Overshooting and No-Overshooting Model Atmospheres

    NASA Astrophysics Data System (ADS)

    Gulati, R. K.; Chavez, M.

    1999-01-01

    Lick indices have been widely used for interpretation of stellar content in the Local Group of galaxies. The behavior of the empirical spectral indices with basic atmospheric parameters, which is used as an input for modeling stellar populations, hampers the study of stellar populations in elliptical galaxies due to its limitation parameter space. We have been investigating the potential of theoretical spectral indices based on atmospheric models in order to complement with the empirical indices. In our earlier works we have (Gulati et al., 1993, ApJ, 413, 166; Chavez, et al., 1996, ApJ 471, 726) looked into two generation of the Kurucz's model atmospheres for consistency with empirical indices. New generation of Kurucz's models, which take into account the convection with mixing length theory with and without approximate overshooting, and model colors based on the latter criterion seem to reproduce more observations. In this paper we investigate the role of convection on the Lick indices and present preliminary results.

  10. Synthesis of imagery with high spatial and spectral resolution from multiple image sources

    NASA Astrophysics Data System (ADS)

    Filiberti, Daniel P.; Marsh, Stuart E.; Schowengerdt, Robert A.

    1994-08-01

    We demonstrate how a realistic scene with high spatial and spectral resolution can be synthesized from color aerial photography and AVIRIS hyperspectral imagery. A review of techniques for image fusion is first presented. Image processing techniques were developed to extract a digital elevation model from stereo aerial photography in order to correct temporal shading differences between two image sets and to fuse aerial photography with AVIRIS imagery. A unique contribution is the explicit inclusion of corrections for topography and differing solar angles in fusion process. Color infrared photography and an AVIRIS image from a site near Cuprite, Nevada, were used as a test of an improved high-frequency modulation technique for the creation of hybrid images. Comparison of spectra extracted from the synthesized image with library spectra demonstrated that our methodology successfully preserved the spectral signatures of the ground surface.

  11. Synthesis, characterization, crystal structure and predicting the second-order optical nonlinearity of a new dicobalt(III) complex with Schiff base ligand

    NASA Astrophysics Data System (ADS)

    Zarei, Seyed Amir; Piltan, Mohammad; Hassanzadeh, Keyumars; Akhtari, Keivan; Cinčić, Dominik

    2015-03-01

    The synthesis and characterization of dicobalt(III) complex [Co2L2(OMe)2] of the tetradentate Schiff base ligand N,N‧-bis(2-hydroxybenzylidene)-2,2-dimethyl-1,3-propanediamine (H2L) is reported. The crystal structure of the complex has been determined that exhibited the pseudo-octahedral geometry around both cobalt(III) ions. In the complexation process, H2L acts as two negatively charged tetradentate ligand, L2-, and methoxy group plays as bridging ligand. The geometry structure of the complex is optimized by density functional theory (DFT) using B3LYP/6-311G(d,p). The calculated geometric parameters are in good agreement with the corresponding experimental data. Second-Order Nonlinear Optical (NLO) property of the complex is evaluated by DFT/B3LYP/6-311G(d,p) on the base of the optimized structure that shows the enhancement relative to the calculated value of H2L. The calculated NLO value of the complex is much greater than the corresponding value of urea.

  12. Synthesis and crystal structure of a series of pyrazolone based Schiff base ligands and DNA binding studies of their copper complexes

    NASA Astrophysics Data System (ADS)

    Jadeja, R. N.; Parihar, Sanjay; Vyas, Komal; Gupta, Vivek K.

    2012-04-01

    PMP (5-methyl-4-(4-methyl-benzoyl)-2-phenyl-2,4-dihydro-pyrazol-3-one), PTPMP (5-methyl-4-(4-methyl-benzoyl)-2-p-tolyl-2,4-dihydro-pyrazol-3-one) and MCPMP (2-(3-Chloro-phenyl)-5-methyl-4-(4-methyl-benzoyl))-2,4-dihydro-pyrazol-3-one) were synthesized and used for the synthesis of Schiff base ligands. Schiff base ligands were characterized by FT-IR, 1H NMR, Mass and single crystal X-ray analysis. Cu(II) complexes of synthesized ligands were prepared and characterized by elemental analysis, FT-IR, TGA-DTA, UV-Visible, ESI mass and ESR spectroscopy. On the basis of analytical and spectroscopic techniques, distorted octahedral geometry of the complexes was proposed. The interaction of Cu(II) complexes with CT-DNA was investigated by Absorption titration, Viscosity and fluorescence spectroscopy. Results suggest that the synthesized complexes bind to DNA via an intercalative mode and can quench the fluorescence intensity of EB bound to DNA.

  13. Synthesis, characterization and electrochemical characterization of lead selenide sub-micron particles capped with a benzoate ligand and prepared at different temperatures

    NASA Astrophysics Data System (ADS)

    Rodríguez-Rodríguez, Weyshla A.; Colón, Jadiel; Guzmán, Roger; Rivera, Harry; Santiago-Berríos, Mitk'El B.

    2014-09-01

    Semiconductor materials offer several potential benefits as active elements in the development of harvesting-energy conversion technologies. In particular, lead selenide (PbSe) semiconductors have been used and proposed to design solar energy harvesting devices, IR sensors, FET devices, etc. Lead salts have drawn particular attention from the applied and fundamental research communities due to their exceptionally strong quantum confinement effects. Several syntheses of PbSe have been proposed using long chain surfactants to allow the formation of particles and nanoparticles. Here we present a synthesis using benzoic acid as the capping ligand in ambient atmosphere. Although the particles are not in nanometric size, we compare the crystal structure (using x-ray powder diffraction data), the near infrared and mid-infrared absorption properties of PbSe using oleic acid as the capping ligand with PbSe using benzoic acid as the capping ligand. The new synthetized particles were shown to have similar crystal structure and absorb light in the near infrared region at 1410 nm. We also performed cyclic voltammetry of these particles drop-casted in the surface of a glassy carbon electrode. The particles showed electrochemical behavior with an oxidation peak near (-402 ± 5 mV) versus Ag/AgCl reference electrode. The particles seem to form a polymeric film at the surface of a glassy carbon electrode.

  14. Synergistic effects of tethered growth factors and adhesion ligands on DNA synthesis and function of primary hepatocytes cultured on soft synthetic hydrogels

    PubMed Central

    Mehta, Geeta; Williams, Courtney M.; Alvarez, Luis; Lesniewski, Martha; Kamm, Roger D.; Griffith, Linda G.

    2010-01-01

    The composition, presentation, and spatial orientation of extracellular matrix molecules and growth factors are key regulators of cell behavior. Here, we used self-assembling peptide nanofiber gels as a modular scaffold to investigate how fibronectin-derived adhesion ligands and different modes of epidermal growth factor (EGF) presentation synergistically regulate multiple facets of primary rat hepatocyte behavior in the context of a soft gel. In the presence of soluble EGF, inclusion of dimeric RGD and the heparin binding domain from fibronectin (HB) increased hepatocyte aggregation, spreading, and metabolic function compared to unmodified gels or gels modified with a single motif, but unlike rigid substrates, gels failed to induce DNA synthesis. Tethered EGF dramatically stimulated cell aggregation and spreading under all adhesive ligand conditions and also preserved metabolic function. Surprisingly, tethered EGF elicited DNA synthesis on gels with RGD and HB. Phenotypic differences between soluble and tethered EGF stimulation of cells on peptide gels are correlated with differences in expression and phosphorylation the EGF receptor and its heterodimerization partner ErbB2, and activation of the downstream signaling node ERK1/2. These modular matrices reveal new facets of hepatocellular biology in culture and may be more broadly useful in culture of other soft tissues. PMID:20304480

  15. Synthesis and structural studies of 1,4-di(2-pyridyl)-1,2,3-triazole and its transition metal complexes; a versatile and subtly unsymmetric ligand.

    PubMed

    McCarney, Eoin P; Hawes, Chris S; Blasco, Salvador; Gunnlaugsson, Thorfinnur

    2016-06-21

    The synthesis of the 'click' derived 1,4-di(2-pyridyl)-1,2,3-triazole () chelator/ligand from 2-azidopyridine and 2-ethynylpyridine using Cu(i) and TBTA by microwave assisted synthesis is presented. The complexes of the subtly unsymmetric ligand with Cu(i), Pt(ii), Co(ii), and Ag(i) were structurally characterised by using conventional methods, as well as using single crystal and powder diffraction analysis. The results of the studies showed formation of discrete molecules displaying preferential binding of the d-metal cations through the pyridyl nitrogen N1 and the proximal triazolyl nitrogen N2 i.e. the 2-(1H-1,2,3-triazol-4-yl)pyridine or 'regular' chelate moiety despite the presence of a second potential binding pocket i.e. the 2-(1H-1,2,3-triazol-1-yl)pyridine chelate or 'inverse' moiety. This binding selectivity was corroborated through the study of the self-assembly of with Cu(i) and Ag(i) using (1)H NMR titration in CD3CN solution, as well as using UV-Vis absorption titrations; the former showing a broadening of the proton peaks associated with that chelate pocket. PMID:27231030

  16. Indole synthesis by conjugate addition of anilines to activated acetylenes and an unusual ligand-free copper(II)-mediated intramolecular cross-coupling.

    PubMed

    Gao, Detian; Back, Thomas G

    2012-11-12

    A versatile new synthesis of indoles was achieved by the conjugate addition of N-formyl-2-haloanilines to acetylenic sulfones, ketones, and esters followed by a copper-catalyzed intramolecular C-arylation. The conjugate addition step was conducted under exceptionally mild conditions at room temperature in basic, aqueous DMF. Surprisingly, the C-arylation was performed most effectively by employing copper(II) acetate as the catalyst in the absence of external ligands, without the need for protection from air or water. An unusual feature of this process, for the case of acetylenic ketones, is the ability of the initial conjugate-addition product to serve as a ligand for the catalyst, which enables it to participate in the catalysis of its further transformation to the final indole product. Mechanistic studies, including EPR experiments, indicated that copper(II) is reduced to the active copper(I) species by the formate ion that is produced by the base-catalyzed hydrolysis of DMF. This process also served to recycle any copper(II) that was produced by the adventitious oxidation of copper(I), thereby preventing deactivation of the catalyst. Several examples of reactions involving acetylenic sulfones attached to a modified Merrifield resin demonstrated the feasibility of solid-phase synthesis of indoles by using this protocol, and tricyclic products were obtained in one pot by employing acetylenic sulfones that contain chloroalkyl substituents. PMID:23019064

  17. Biogenic silver nanoparticles using Rhinacanthus nasutus leaf extract: synthesis, spectral analysis, and antimicrobial studies

    PubMed Central

    Pasupuleti, Visweswara Rao; Prasad, TNVKV; Shiekh, Rayees Ahmad; Balam, Satheesh Krishna; Narasimhulu, Ganapathi; Reddy, Cirandur Suresh; Rahman, Ismail Ab; Gan, Siew Hua

    2013-01-01

    Nanotechnology is gaining momentum due to its ability to transform metals into nanoparticles. The synthesis, characterization, and applications of biologically synthesized nanomaterials have become an important branch of nanotechnology. Plant extracts are a cost-effective, ecologically friendly, and efficient alternative for the large-scale synthesis of nanoparticles. In this study, silver nanoparticles (AgNps) were synthesized using Rhinacanthus nasutus leaf extract. After exposing the silver ions to the leaf extract, the rapid reduction of silver ions led to the formation of AgNps in solution. The synthesis was confirmed by ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy, and transmission electron microscopy. The in vitro antimicrobial activity of the AgNps synthesized using R. nasutus leaf extract was investigated against Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumonia, Escherichia coli, Aspergillus niger, and Aspergillus flavus using a disc diffusion method. The AgNps showed potential activity against all of the bacterial strains and fungal colonies, indicating that R. nasutus has the potential to be used in the development of value-added products in the biomedical and nanotechnology-based industries. PMID:24039419

  18. Troponate/Aminotroponate Ruthenium-Arene Complexes: Synthesis, Structure, and Ligand-Tuned Mechanistic Pathway for Direct C-H Bond Arylation with Aryl Chlorides in Water.

    PubMed

    Dwivedi, Ambikesh D; Binnani, Chinky; Tyagi, Deepika; Rawat, Kuber S; Li, Pei-Zhou; Zhao, Yanli; Mobin, Shaikh M; Pathak, Biswarup; Singh, Sanjay K

    2016-07-01

    A series of water-soluble troponate/aminotroponate ruthenium(II)-arene complexes were synthesized, where O,O and N,O chelating troponate/aminotroponate ligands stabilized the piano-stool mononuclear ruthenium-arene complexes. Structural identities for two of the representating complexes were also established by single-crystal X-ray diffraction studies. These newly synthesized troponate/aminotroponate ruthenium-arene complexes enable efficient C-H bond arylation of arylpyridine in water. The unique structure-activity relationship in these complexes is the key to achieve efficient direct C-H bond arylation of arylpyridine. Moreover, the steric bulkiness of the carboxylate additives systematically directs the selectivity toward mono- versus diarylation of arylpyridines. Detailed mechanistic studies were performed using mass-spectral studies including identification of several key cyclometalated intermediates. These studies provided strong support for an initial cycloruthenation driven by carbonate-assisted deprotonation of 2-phenylpyridine, where the relative strength of η(6)-arene and the troponate/aminotroponate ligand drives the formation of cyclometalated 2-phenylpyridine Ru-arene species, [(η(6)-arene)Ru(κ(2)-C,N-phenylpyridine) (OH2)](+) by elimination of troponate/aminotroponate ligands and retaining η(6)-arene, while cyclometalated 2-phenylpyridine Ru-troponate/aminotroponate species [(κ (2)-troponate/aminotroponate)Ru(κ(2)-C,N-phenylpyridine)(OH2)2] was generated by decoordination of η(6)-arene ring during initial C-H bond activation of 2-phenylpyridine. Along with the experimental mass-spectral evidence, density functional theory calculation also supports the formation of such species for these complexes. Subsequently, these cycloruthenated products activate aryl chloride by facile oxidative addition to generate C-H arylated products. PMID:27305143

  19. Synthesis, spectral studies and biological evaluation of 2-aminonicotinic acid metal complexes.

    PubMed

    Nawaz, Muhammad; Abbasi, Muhammad Waseem; Hisaindee, Soleiman; Zaki, Muhammad Javed; Abbas, Hira Fatima; Mengting, Hu; Ahmed, M Arif

    2016-05-15

    We synthesized 2-aminonicotinic acid (2-ANA) complexes with metals such as Co(II), Fe(III), Ni(II), Mn(II), Zn(II), Ag(I),Cr(III), Cd(II) and Cu(II) in aqueous media. The complexes were characterized and elucidated using FT-IR, UV-Vis, a fluorescence spectrophotometer and thermo gravimetric analysis (TGA). TGA data showed that the stoichiometry of complexes was 1:2 metal/ligand except for Ag(I) and Mn(II) where the ratio was 1:1. The metal complexes showed varied antibacterial, fungicidal and nematicidal activities. The silver and zinc complexes showed highest activity against Bacillus subtilis and Bacillus licheniformis respectively. Fusarium oxysporum was highly susceptible to nickel and copper complexes whereas Macrophomina phaseolina was completely inert to the complexes. The silver and cadmium complexes were effective against the root-knot nematode Meloidogyne javanica. PMID:26945123

  20. Synthesis, spectral studies and biological evaluation of 2-aminonicotinic acid metal complexes

    NASA Astrophysics Data System (ADS)

    Nawaz, Muhammad; Abbasi, Muhammad Waseem; Hisaindee, Soleiman; Zaki, Muhammad Javed; Abbas, Hira Fatima; Mengting, Hu; Ahmed, M. Arif

    2016-05-01

    We synthesized 2-aminonicotinic acid (2-ANA) complexes with metals such as Co(II), Fe(III), Ni(II), Mn(II), Zn(II), Ag(I),Cr(III), Cd(II) and Cu(II) in aqueous media. The complexes were characterized and elucidated using FT-IR, UV-Vis, a fluorescence spectrophotometer and thermo gravimetric analysis (TGA). TGA data showed that the stoichiometry of complexes was 1:2 metal/ligand except for Ag(I) and Mn(II) where the ratio was 1:1. The metal complexes showed varied antibacterial, fungicidal and nematicidal activities. The silver and zinc complexes showed highest activity against Bacillus subtilis and Bacillus licheniformis respectively. Fusarium oxysporum was highly susceptible to nickel and copper complexes whereas Macrophomina phaseolina was completely inert to the complexes. The silver and cadmium complexes were effective against the root-knot nematode Meloidogyne javanica.

  1. Coordination mode of pentadentate ligand derivative of 5-amino-1,3,4-thiadiazole-2-thiol with nickel(II) and copper(II) metal ions: Synthesis, spectroscopic characterization, molecular modeling and fungicidal study

    NASA Astrophysics Data System (ADS)

    Chandra, Sulekh; Gautam, Seema; Kumar, Amit; Madan, Molly

    2015-02-01

    Complexes of nickel(II), and copper(II) were synthesized with pantadentate ligand i.e. 3,3‧-thiodipropionicacid-bis(5-amino-1,3,4-thiadiazole-2-thiol) (L). The ligand was synthesized by the condensation of thiodipropionic acid and 5-amino-1,3,4-thiadiazole-2-thiol in 1:2 ratio, respectively. Synthesized ligand was characterized by elemental analysis, mass, 1H NMR, IR, and molecular modeling. All the complexes were characterized by elemental analysis, molar conductance, magnetic moment, IR, electronic spectra, ESR, and molecular modeling. The newly synthesized complexes possessed general composition [M(L)X2] where M = Ni(II), Cu(II), L = pantadentate ligand and X = Cl-, CH3COO-. The IR spectral data indicated that the ligand behaved as a pantadentate ligand and coordinated to the metal ion through N2S3 donor atoms. The molar conductance value of Ni(II), and Cu(II) complexes in DMSO corresponded to their electrolytic behavior. On the basis of spectral study, octahedral and tetragonal geometry was assigned for Ni(II) and Cu(II) complexes, respectively. In vitro fungicidal study of ligand and its complexes was investigated against fungi Candida albicans, Candida parapsilosis, Candidia krusei, and Candida tropicalis by means of well diffusion method.

  2. Ligand modeling and design

    SciTech Connect

    Hay, B.P.

    1997-10-01

    The purpose of this work is to develop and implement a molecular design basis for selecting organic ligands that would be used in the cost-effective removal of specific radionuclides from nuclear waste streams. Organic ligands with metal ion specificity are critical components in the development of solvent extraction and ion exchange processes that are highly selective for targeted radionuclides. The traditional approach to the development of such ligands involves lengthy programs of organic synthesis and testing, which in the absence of reliable methods for screening compounds before synthesis, results in wasted research effort. The author`s approach breaks down and simplifies this costly process with the aid of computer-based molecular modeling techniques. Commercial software for organic molecular modeling is being configured to examine the interactions between organic ligands and metal ions, yielding an inexpensive, commercially or readily available computational tool that can be used to predict the structures and energies of ligand-metal complexes. Users will be able to correlate the large body of existing experimental data on structure, solution binding affinity, and metal ion selectivity to develop structural design criteria. These criteria will provide a basis for selecting ligands that can be implemented in separations technologies through collaboration with other DOE national laboratories and private industry. The initial focus will be to select ether-based ligands that can be applied to the recovery and concentration of the alkali and alkaline earth metal ions including cesium, strontium, and radium.

  3. Structural, spectral analysis and DNA studies of heterocyclic thiosemicarbazone ligand and its Cr(III), Fe(III), Co(II) Hg(II), and U(VI) complexes

    NASA Astrophysics Data System (ADS)

    Yousef, T. A.; Abu El-Reash, G. M.; El Morshedy, R. M.

    2013-08-01

    The paper presents a combined experimental and computational study of novel Cr(III), Fe(III), Co(II), Hg(II) and U(VI) complexes of (E)-2-((3-hydroxynaphthalen-2-yl)methylene)-N-(pyridin-2-yl)hydrazinecarbothioamide (H2L). The ligand and its complexes have been characterized by elemental analyses, spectral (IR, UV-vis, 1H NMR and 13C NMR), magnetic and thermal studies. IR spectra show that H2L is coordinated to the metal ions in a mononegative bi or tri manner. The structures are suggested to be octahedral for all complexes except Hg(II) complex is tetrahedral. Theoretical calculations have been performed to obtain IR spectra of ligand and its complexes using AM1, MM, Zindo/1, MM+ and PM3, methods. Satisfactory theoretical-experimental agreements were achieved by MM method for the ligand and PM3 for its complexes. DOS calculations carried out by MM (ADF) method for ligand Hg complex from which we concluded that the thiol form of the ligand is more active than thione form and this explains that the most complexation take place in that form. The calculated IR vibrations of the metal complexes, using the PM3 method was the nearest method for the experimental data, and it could be used for all complexes. Also, valuable information are obtained from calculation of molecular parameters for all compounds carried out by the previous methods of calculation (electronegativity of the coordination sites, net dipole moment of the metal complexes, values of heat of formation and binding energy) which approved that the complexes are more stable than ligand. The low value of ΔE could be expected to indicate H2L molecule has high inclination to bind with the metal ions. Furthermore, the kinetic and thermodynamic parameters for the different decomposition steps were calculated using the Coats-Redfern and Horowitz-Metzger methods. Finally, the biochemical studies showed that, complex 2, 4 have powerful and complete degradation effect on DNA. For the foremost majority of cases the

  4. Synthesis and properties of new mononuclear Ru(ii)-based photocatalysts containing 4,4'-diphenyl-2,2'-bipyridyl ligands.

    PubMed

    Coe, Benjamin J; Sánchez, Sergio

    2016-03-15

    The synthesis and characterisation of a series of eleven new 4,4'-diphenyl-2,2'-bipyridyl derivatives (N^N) with varying 4- or 3,5-substituents on the phenyl rings are reported. The molecular structures of two of these compounds, 4,4'-bis(3,5-diheptyloxyphenyl)-2,2'-bipyridyl and 4,4'-bis(3,5-di-4,4,5,5,5-pentafluoropentyloxyphenyl)-2,2'-bipyridyl are confirmed by X-ray crystallography. Fourteen neutral complexes trans-Ru(II)Cl2(N^N)(CO)2 are prepared by reacting the new proligands and three known ones with the polymeric precursor [Ru(II)Cl2(CO)2]n, and their optical and electrochemical properties are studied. Density functional theory (DFT) and time-dependent DFT calculations have been carried out on selected complexes in order to rationalise their electronic structures and absorption properties. The low energy electronic absorption bands have metal-to-ligand charge-transfer and ligand-to-ligand charge-transfer (LLCT) character, but these dominate only in the 4-substituted species. In the 3,5-disubstituted ones, intraligand charge-transfer (ILCT) within the bpy ligands becomes more important. The complexes show only irreversible reductive electrochemistry and no signs of polymerisation. The photocatalytic oxidation behaviour of selected trans-Ru(II)Cl2(N^N)(CO)2 complexes and their mono-aquo derivatives [Ru(II)(H2O)(CO)2Cl(N^N)](+) with 4-methoxybenzyl alcohol is studied. Turnover numbers of up to ca. 130 are achieved when using [Ru(II)(bpy)3](2+) (bpy = 2,2'-bipyridyl) as photosensitizer and [Co(III)(NH3)5Cl](2+) as a sacrificial oxidant. PMID:26890960

  5. PPAR ligand association with prostaglandin F2α and E2 synthesis in the pig corpus luteum-An in vitro study.

    PubMed

    Kurzynska, A; Chojnowska, K; Bogacki, M; Bogacka, I

    2016-09-01

    The present study evaluated the involvement of PPARs in prostaglandin (PG) E2 and F2α production in the corpus luteum (CL) of pigs on days 10-12 and 14-16 of the estrous cycle or pregnancy. The tissue explants were incubated for 6h in the presence of PPARα, PPARβ, PPARγ ligands. The concentration of PGs in the incubation media was determined by radioimmunoassay, while mRNA abundance of PG synthetases (PGES and PGFS) was analyzed by quantitative real-time PCR. It was found that L-165,045 and rosiglitazone stimulated PGES synthesis on days 10-12 of the estrous cycle, whereas all factors that were assessed did not affect PGE2 release. The PGFS mRNA abundance in the CL did not change in the presence of PPAR ligands during the assessment periods. However, PPARβ agonist inhibited PGF2α secretion on days 10-12 of the estrous cycle and on days 14-16 of pregnancy. Interestingly, PPAR antagonists, MK 886, GW 9662 or T0070907 decreased PGF2α release by the slices on days 10-12 of the estrous cycle. It is concluded that the CL has a different susceptibility (greatest during mid-luteal phase of the estrous cycle) to the PPAR ligands, which is related to the physiological status of animal. The inhibition of PGF2α release and augmentation of PGES mRNA concentration during mid-luteal phase of the estrous cycle might suggest luteotropic properties of PPAR ligands. PMID:27477116

  6. Sensitivity to Flg22 Is Modulated by Ligand-Induced Degradation and de Novo Synthesis of the Endogenous Flagellin-Receptor FLAGELLIN-SENSING2[W][OPEN

    PubMed Central

    Smith, John M.; Salamango, Daniel J.; Leslie, Michelle E.; Collins, Carina A.; Heese, Antje

    2014-01-01

    FLAGELLIN-SENSING2 (FLS2) is the plant cell surface receptor that perceives bacterial flagellin or flg22 peptide, initiates flg22-signaling responses, and contributes to bacterial growth restriction. Flg22 elicitation also leads to ligand-induced endocytosis and degradation of FLS2 within 1 h. Why plant cells remove this receptor precisely at the time during which its function is required remains mainly unknown. Here, we assessed in planta flg22-signaling competency in the context of ligand-induced degradation of endogenous FLS2 and chemical interference known to impede flg22-dependent internalization of FLS2 into endocytic vesicles. Within 1 h after an initial flg22 treatment, Arabidopsis (Arabidopsis thaliana) leaf tissue was unable to reelicit flg22 signaling in a ligand-, time-, and dose-dependent manner. These results indicate that flg22-induced degradation of endogenous FLS2 may serve to desensitize cells to the same stimulus (homologous desensitization), likely to prevent continuous signal output upon repetitive flg22 stimulation. In addition to impeding ligand-induced FLS2 degradation, pretreatment with the vesicular trafficking inhibitors Wortmannin or Tyrphostin A23 impaired flg22-elicited reactive oxygen species production that was partially independent of BRASSINOSTEROID INSENSITIVE1-ASSOCIATED KINASE1. Interestingly, these inhibitors did not affect flg22-induced mitogen-activated protein kinase phosphorylation, indicating the ability to utilize vesicular trafficking inhibitors to target different flg22-signaling responses. For Tyrphostin A23, reduced flg22-induced reactive oxygen species could be separated from the defect in FLS2 degradation. At later times (>2 h) after the initial flg22 elicitation, recovery of FLS2 protein levels positively correlated with resensitization to flg22, indicating that flg22-induced new synthesis of FLS2 may prepare cells for a new round of monitoring the environment for flg22. PMID:24220680

  7. Synthesis and Optical Properties of Thiol Functionalized CdSe/ZnS (Core/Shell) Quantum Dots by Ligand Exchange

    SciTech Connect

    Zhu, Huaping; Hu, Michael Z.; Shao, Lei; Yu, Kui; Dabestani, Reza T; Zaman, Md. Badruz; Liao, Dr. Shijun

    2014-03-20

    The colloidal photoluminescent quantum dots (QDs) of CdSe (core) and CdSe/ZnS (core/shell) were synthesized at different temperatures with different growth periods. The optical properties (i.e., UV/Vis spectra and photoluminescent emission spectra) of the resulting QDs were investigated. The CdSe/ZnS QDs exhibited higher photoluminescent (PL) efficiency and stability than their corresponding CdSe core QDs. Ligand exchange with various thiol molecules was performed to replace the initial surface passivation ligands, that is, trioctylphosphine oxide (TOPO) and trioctylphosphine (TOP), and the optical properties of the surface-modified QDs were studied. The thiol ligand molecules used included 1,4-benzenedimethanethiol, 1,16-hexadecanedithiol, 1,11-undecanedithiol, 11-mercapto-1-undecanol, and 1,8 octanedithiol. After the thiol functionalization, the CdSe/ZnS QDs exhibited significantly enhanced PL efficiency and storage stability. Besides surface passivation effect, such enhanced performance of thiol-functionalized QDs could be due to self-assembly formation of dimer/trimer clusters, in which QDs are linked by dithiol molecules. Effects of ligand concentration, type of ligand, and heating on the thiol stabilization of QDs were also discussed.

  8. Synthesis, structural characterization, catalytic, thermal and electrochemical investigations of bidentate Schiff base ligand and its metal complexes

    NASA Astrophysics Data System (ADS)

    Dolaz, Mustafa; McKee, Vickie; Uruş, Serhan; Demir, Necmettin; Sabik, Ali E.; Gölcü, Ayşegül; Tümer, Mehmet

    2010-07-01

    In this study, we prepared the Schiff base ligand (L) and its Cu(II), Co(II) and Ni(II) complexes. The compounds were characterized by the analytical and spectroscopic methods. The ligand (L) behaves as a bidentate ligand and coordinates to the metal ions via the nitrogen atoms. The complexes have the mononuclear structures. The analytical and spectroscopic results indicated that the chloride ions coordinate to the metal ions. The complexes have the general formulae [M(L)(Cl) 2] (M: Cu(II), Co(II) and Ni(II) metal ions). Electrochemical properties were investigated as ligand and metal centres in the different solvents and at the scan rates, respectively. The thermal properties of the metal complexes were studied in the N 2 atmosphere. We investigated the improved catalytic activity of the Cu(II), Co(II) and Ni(II) complexes on the cyclohexane as a substrate. Obtained data showed that the best catalyst is the Cu(II) complex. The single crystal of the ligand (L) was obtained from CH 3CN solution. There is a C-H…N H-bond linking the molecules into chains (C6)…N(2) 3.4415(18) Å under symmetry operation ( x + 1, y, z) as well as π-π stacking on the outside of the "V" shape - nothing on the inside.

  9. Palladium(II) and platinum(II) derivatives of benzothiazoline ligands: Synthesis, characterization, antimicrobial and antispermatogenic activity

    NASA Astrophysics Data System (ADS)

    Sharma, Krishna; Singh, R. V.; Fahmi, Nighat

    2011-01-01

    A series of Pd(II) and Pt(II) complexes with two N ∩S donor ligands, 5-chloro-3-(indolin-2-one)benzothiazoline and 6-nitro-3-(indolin-2-one)benzothiazoline, have been synthesized by the reaction of metal chlorides (PdCl 2 and PtCl 2) with ligands in 1:2 molar ratios. All the synthesized compounds were characterized by elemental analyses, melting point determinations and a combination of electronic, IR, 1H NMR and 13C NMR spectroscopic techniques for structure elucidation. In order to evaluate the effect of metal ions upon chelation, both the ligands and their complexes have been screened for their antimicrobial activity against the various pathogenic bacterial and fungal strains. The metal complexes have shown to be more antimicrobial against the microbial species as compared to free ligands. One of the ligands, 5-chloro-3-(indolin-2-one)benzothiazoline and its corresponding palladium and platinum complexes have been tested for their antifertility activity in male albino rats. The marked reduction in sperm motility and density resulted in infertility by 62-90%. Significant alterations were found in biochemical parameters of reproductive organs in treated animals as compared to control group. It is concluded that all these effects may finally impair the fertility of male rats.

  10. Synthesis and Reactivity of Low-Coordinate Titanium Synthons Supported by a Reduced Redox-Active Ligand.

    PubMed

    Clark, Kensha Marie

    2016-07-01

    To further explore the reactivity and redox capability of the bis-arylimino acenaphthylene ligand (BIAN) in early transition metal complexes, the coordinatively unsaturated titanium synthons, [(dpp-BAAN)Ti(R)2] ([dpp-BAAN](2-) = N,N'-bis(2,6-diisopropylphenylamido)acenaphthylene and R = O(t)Bu (2) or CH2C(CH3)3 (3)), in which the BAAN ligand is reduced by two electrons, were isolated in good yields via sterically induced radical elimination reactions. Addition of p-tolyl azide to complex 3 initiated reductive elimination of the neopentyl ligands to generate a putative imido species. The imido species was trapped by a second oxidative addition of chloride ligands to yield the titanium imido complex, [(dpp-BIAN)Ti[═N(4-C6H4Me)]Cl2 (4). These reactions demonstrate that the BAAN ligand can provide redox equivalents for enhanced reactivity that includes oxidative addition and reductive elimination at d(0) metal centers. PMID:27304996

  11. 80 GHz waveform generated by the optical Fourier synthesis of four spectral sidebands

    NASA Astrophysics Data System (ADS)

    Fatome, Julien; Hammani, Kamal; Kibler, Bertrand; Finot, Christophe

    2016-01-01

    Using the linear phase shaping of a simple four-line optical frequency comb, we experimentally demonstrate the generation of various optical waveforms such as parabolic, triangular or flat-top pulse trains at a repetition rate of 80 GHz. The initial 80 GHz comb is obtained through the nonlinear spectral broadening of a 40 GHz carrier-suppressed sinusoidal beating in a highly nonlinear fiber. Proof-of-principle experiments are reported for two distinct configurations of the waveform generated: continuous trains and bunches of shaped pulses.

  12. Synthesis, spectral, antitumor and antimicrobial studies on Cu(II) complexes of purine and triazole Schiff base derivatives

    NASA Astrophysics Data System (ADS)

    Amer, Said; El-Wakiel, Nadia; El-Ghamry, Hoda

    2013-10-01

    A series of copper (II) complexes of Schiff bases derived from 7H-2,6-diaminopurine and 4H-3,5-diamino-1,2,4-triazole with 2-pyridinecarbaldehyde, salicylaldehyde, 2,4-dihydroxybenzaldehyde and 2-hydroxy-1-naphthaldehyde have been prepared. The donor atoms and the possible geometry of the complexes were investigated by means of elemental and thermal analyses, molar conductance, magnetic moment, UV-Vis, IR, ESR and mass spectra. The ligands behaved as tetradentate, coordinating through the nitrogen atom of the azomethine group and the nearest nitrogen atom to it or oxygen atom of α-hydroxyl group. The results of simultaneous DTA & TGA analyses of the complexes showed the final degradation product for these complexes is CuO. The spectral studies confirmed a four coordinate environment around the metal ion. The obtained results were supported by 3D molecular modeling of complexes using molecular mechanics (MM+) and semiempirical molecular orbital calculations (PM3). These complexes were also tested for their in vitro antimicrobial activities against some bacterial and fungal strains. Complex 2 was investigated for its cyctotoxic effect against human breast cancer (MCF7), liver carcinoma (HEPG2) and colon carcinoma cell lines (HCT116). This compound exhibited a moderate activity against the tested cell lines with IC50 of 10.3, 9.8 and 8.7 μg/ml against MCF7, HCT116 and HEPG2, respectively.

  13. Synthesis, spectral characterization, crystal structure and molecular docking study of 2,7-diaryl-1,4-diazepan-5-ones

    NASA Astrophysics Data System (ADS)

    Sethuvasan, S.; Sugumar, P.; Maheshwaran, V.; Ponnuswamy, M. N.; Ponnuswamy, S.

    2016-07-01

    In this study, a series of variously substituted r-2,c-7-diaryl-1,4-diazepan-5-ones 9-16 have been synthesized using Schmidt rearrangement and are characterized by IR, mass and 1D & 2D NMR spectral data. The proton NMR coupling constant and estimated dihedral angles reveal that the compounds 9-16 prefer a chair conformation with equatorial orientation of alkyl and aryl groups. Single crystal X-ray structure has been solved for compounds 9 and 11 which also indicates the preference for distorted chair conformation with equatorial orientation of substituents. The compounds 9-16 have been docked with the structure of Methicillin-resistant Staphylococcus aureus (MRSA) and the results demonstrate that compound 10 is having better docking score and glide energy than others and it is comparable to co-crystal ligand. Furthermore, all the compounds have been evaluated for their antibacterial and antioxidant activities. All the compounds show moderate antibacterial activity and only 11 exhibits better activity against S. aures and Escherichia coli. The compounds 11, 13 and 14 exhibit half of the antioxidant power when compared to the BHT and the remaining compounds show moderate activity.

  14. Synthesis, spectral, antimicrobial and antitumor assessment of Schiff base derived from 2-aminobenzothiazole and its transition metal complexes

    NASA Astrophysics Data System (ADS)

    Etaiw, Safaa Eldin H.; Abd El-Aziz, Dina M.; Abd El-Zaher, Eman H.; Ali, Elham A.

    2011-09-01

    N-(thiophen-2-ylmethylene)benzo[ d]thiazol-2-amine Schiff base (L) derived from 2-aminobenzothiazole and 2-thiophenecarboxaldehyde was synthesized and characterized using elemental analysis, IR, mass spectra, 1H NMR and UV-vis spectra. Its complexes with Cu(II), Fe(III), Ni(II) and Zn(II) were prepared and isolated as solid products and characterized by elemental and thermal analyses, spectral techniques as well as magnetic susceptibility. The IR spectra showed that the Schiff base under investigation behaves as bidentate ligand. The UV-vis spectra and magnetic moment data suggested octahedral geometry around Cu(II) and Fe(III) and tetrahedral geometry around Ni(II) and Zn(II). In view of the biological activity of the Schiff base and its complexes, it has been observed that the antimicrobial activity of the Schiff base increased on complexation with the metal ion. In vitro antitumor activity assayed against five human tumor cell lines furnished the significant toxicities of the Schiff base and its complexes.

  15. Synthesis, Spectral Analysis and Preliminary in Vitro Evaluation of Some Tetrapyrrolic Complexes with 3d Metal Ions.

    PubMed

    Socoteanu, Radu; Manda, Gina; Boscencu, Rica; Vasiliu, Georgiana; Oliveira, Anabela Sousa

    2015-01-01

    In this paper, two tetrapyrrolic complexes, Zn(II)-5-(3-hydroxyphenyl)-10,15,20-tris-(4-acetoxy-3-methoxyphenyl)porphyrin and Cu(II)-5-(3-hydroxyphenyl)-10,15,20-tris-(4-acetoxy-3-methoxyphenyl)porphyrin were synthesized, and characterized from a spectral and biological point of view. The study provided data concerning the behavior of identical external substituents vs. two different core insertions. Some of the properties of the proposed tetrapyrrolic structures were highlighted, having photodynamic therapy of cancer as a targeted biomedical application. Elemental analysis, NMR, FTIR and UV-Vis data in various solvents were provided. A preliminary in vitro study on normal and cancer cultured cells was carried out for biocompatibility assessment in dark conditions. The preliminary in vitro study performed on human peripheral mononuclear cells exposed to tetrapyrrolic compounds (2 µM) showed that the proposed compounds had a convenient cytotoxic profile on human normal peripheral blood mononuclear cells under dark conditions. Meanwhile, the investigated compounds reduced the number of metabolically active breast tumor MCF-7 cells, with the exception of Zn(II) complex-containing a symmetrical ligand. Accordingly, preliminary in vitro data suggest that the proposed tetrapyrrolic compounds are good candidates for PDT, as they limit tumor expansion even under dark conditions, whilst sparing normal cells. PMID:26343614

  16. Synthesis, spectral characterization, crystal structure and molecular docking study of 2,7-diaryl-1,4-diazepan-5-ones

    NASA Astrophysics Data System (ADS)

    Sethuvasan, S.; Sugumar, P.; Maheshwaran, V.; Ponnuswamy, M. N.; Ponnuswamy, S.

    2016-07-01

    In this study, a series of variously substituted r-2,c-7-diaryl-1,4-diazepan-5-ones 9-16 have been synthesized using Schmidt rearrangement and are characterized by IR, mass and 1D & 2D NMR spectral data. The proton NMR coupling constant and estimated dihedral angles reveal that the compounds 9-16 prefer a chair conformation with equatorial orientation of alkyl and aryl groups. Single crystal X-ray structure has been solved for compounds 9 and 11 which also indicates the preference for distorted chair conformation with equatorial orientation of substituents. The compounds 9-16 have been docked with the structure of Methicillin-resistant Staphylococcus aureus (MRSA) and the results demonstrate that compound 10 is having better docking score and glide energy than others and it is comparable to co-crystal ligand. Furthermore, all the compounds have been evaluated for their antibacterial and antioxidant activities. All the compounds show moderate antibacterial activity and only 11 exhibits better activity against S. aures and Escherichia coli. The compounds 11, 13 and 14 exhibit half of the antioxidant power when compared to the BHT and the remaining compounds show moderate activity.

  17. Structural, spectral and biological studies of binuclear tetradentate metal complexes of N 3O Schiff base ligand synthesized from 4,6-diacetylresorcinol and diethylenetriamine

    NASA Astrophysics Data System (ADS)

    Emara, Adel A. A.

    2010-09-01

    The binuclear Schiff base, H 2L, ligand was synthesized by reaction of 4,6-diacetylresorcinol with diethylenetriamine in the molar ratio 1:2. The coordination behavior of the H 2L towards Cu(II), Ni(II), Co(II), Zn(II), Fe(III), Cr(III), VO(IV) and UO 2(VI) ions has been investigated. The elemental analyses, magnetic moments, thermal studies and IR, electronic, 1H NMR, ESR and mass spectra were used to characterize the isolated ligand and its metal complexes. The ligand acts as dibasic with two N 3O-tetradentate sites and can coordinate with two metal ions to form binuclear complexes. The bonding sites are the nitrogen atoms of the azomethine and amine groups and the oxygen atoms of the phenolic groups. The metal complexes exhibit either square planar, tetrahedral, square pyramid or octahedral structures. The Schiff base ligand and its metal complexes were tested against four pathogenic bacteria ( Staphylococcus aureus and Streptococcus pyogenes) as Gram-positive bacteria, and ( Pseudomonas fluorescens and Pseudomonas phaseolicola) as Gram-negative bacteria and two pathogenic fungi ( Fusarium oxysporum and Aspergillus fumigatus) to assess their antimicrobial properties. Most of the complexes exhibit mild antibacterial and antifungal activities against these organisms.

  18. 2-Mercapto-1-t-butylimidazolyl as a Bridging Ligand: Synthesis and Structural Characterization of Nickel and Palladium Paddlewheel Complexes‡

    PubMed Central

    Pang, Keliang; Figueroa, Joshua S.; Tonks, Ian A.; Sattler, Wesley

    2009-01-01

    Nickel and palladium paddlewheel complexes that feature 2-mercapto-1-t-butylimidazolyl (mimBut) bridging ligands, namely Ni2[mim But]4 and Pd2[mim But]4, have been synthesized and structurally characterized by X–ray diffraction. Since the mim But ligand bridges in an asymmetric manner via a sulfur and nitrogen donor, paddlewheel compounds of the type M2[mim But]4 may exist as isomers that are distinguished by the relative orientations of the ligands. In this regard, the (4,0)-Ni2[mim But]4 and trans-(2,2)-Ni2[mim But]4 isomers have been isolated for the nickel system, while the (4,0)-Pd2[mim But]4 and (3,1)-Pd2[mim But]4 isomers have been isolated for the palladium system. PMID:20161357

  19. Atomic Data for X-ray Spectrum Synthesis: Sensitivity Analysis and Consequences for Spectral Fitting

    NASA Astrophysics Data System (ADS)

    Kallman, Timothy R.

    2006-09-01

    A great deal of work has been devoted to the accumulation of accurate quantities describing atomic processes for use in analysis of astrophysical spectra. But in many situations of interest the interpretation of a quantity which is observed, such as a line flux, depends on the results of a modeling- or spectrum synthesis code. The results of such a code depends in turn on many atomic rates or cross sections, and the sensitivity of the observable quantity on the various rates and cross sections may be non-linear and if so cannot easily be derived analytically. In such cases the most practical approach to understanding the sensitivity of observables to atomic cross sections is to perform numerical experiments, by calculating models with various rates perturbed by random (but known) factors. In addition, it is useful to compare the results of such experiments with some sample observations, in order to focus attention on the rates which are of the greatest relevance to real observations. I will present some attempts to carry out this program, focussing on two sample datasets taken with the Chandra HETG. I will discuss the sensitivity of synthetic spectra to atomic data affecting ionization balance, temperature, and line opacity or emissivity, and discuss the implications for the ultimate goal of inferring astrophysical parameters. In addition, I will discuss the likely effects on the ionization balance and spectrum synthesis due to the adoption of some recent calculations of dielectronic recombination rate coefficients.

  20. Pyridinoacridine alkaloids of marine origin: NMR and MS spectral data, synthesis, biosynthesis and biological activity

    PubMed Central

    Kuete, Victor; Biavatti, Maique W

    2015-01-01

    Summary This review focuses on pyridoacridine-related metabolites as one biologically interesting group of alkaloids identified from marine sources. They are produced by marine sponges, ascidians and tunicates, and they are structurally comprised of four to eight fused rings including heterocycles. Acridine, acridone, dihydroacridine, and quinolone cores are features regularly found in these alkaloid skeletons. The lack of hydrogen atoms next to quaternary carbon atoms for two or three rings makes the chemical shift assignment a difficult task. In this regard, one of the aims of this review is the compilation of previously reported, pyridoacridine 13C NMR data. Observations have been made on the delocalization of electrons and the presence of some functional groups that lead to changes in the chemical shift of some carbon resonances. The lack of mass spectra information for these alkaloids due to the compactness of their structures is further discussed. Moreover, the biosynthetic pathways of some of these metabolites have been shown since they could inspire biomimetic synthesis. The synthesis routes used to prepare members of these marine alkaloids (as well as their analogues), which are synthesized for biological purposes are also discussed. Pyridoacridines were found to have a large spectrum of bioactivity and this review highlights and compares the pharmacophores that are responsible for the observed bioactivity. PMID:26664587

  1. Ruthenium(II) bipyridine complexes bearing new keto-enol azoimine ligands: Synthesis, structure, electrochemistry and DFT calculations

    NASA Astrophysics Data System (ADS)

    Al-Noaimi, Mousa; Awwadi, Firas F.; Mansi, Ahmad; Abdel-Rahman, Obadah S.; Hammoudeh, Ayman; Warad, Ismail

    2015-01-01

    The novel azoimine ligand, Phsbnd NHsbnd Ndbnd C(COCH3)sbnd NHPh(Ctbnd CH) (H2L), was synthesized and its molecular structure was determined by X-ray crystallography. Catalytic hydration of the terminal acetylene of H2L in the presence of RuCl3·3H2O in ethanol at reflux temperature yielded a ketone (L1 = Phsbnd Ndbnd Nsbnd C(COCH3)dbnd Nsbnd Ph(COCH3) and an enol (L2 = Phsbnd Ndbnd Nsbnd C(COCH3)dbnd Nsbnd PhC(OH)dbnd CH2) by Markovnikov addition of water. Two mixed-ligand ruthenium complexes having general formula, trans-[Ru(bpy)(Y)Cl2] (1-2) (where Y = L1 (1) and Y = L2 (2), bpy is 2.2‧-bipyrdine) were achieved by the stepwise addition of equimolar amounts of (H2L) and bpy ligands to RuCl3·3H2O in absolute ethanol. Theses complexes were characterized by elemental analyses and spectroscopic (IR, UV-Vis, and NMR (1D 1H NMR, 13C NMR, (DEPT-135), (DEPT-90), 2D 1H-1H and 13C-1H correlation (HMQC) spectroscopy)). The two complexes exhibit a quasi-reversible one electron Ru(II)/Ru(III) oxidation couple at 604 mV vs. ferrocene/ferrocenium (Cp2Fe0/+) couple along with one electron ligand reduction at -1010 mV. The crystal structure of complex 1 showed that the bidentate ligand L1 coordinates to Ru(II) by the azo- and imine-nitrogen donor atoms. The complex adopts a distorted trans octahedral coordination geometry of chloride ligands. The electronic spectra of 1 and 1+ in dichloromethane have been modeled by time-dependent density functional theory (TD-DFT).

  2. Synthesis and structure of a 2D Zn complex with mixed ligands stacked in offset ABAB manner

    NASA Astrophysics Data System (ADS)

    Qin, Ling; Wang, Yan-Qing; Ni, Gang

    2016-07-01

    The title complex, {[Zn(ODIB)1/2( bpdc)]·2DMF} n was prepared under hydrothermal conditions (dimethylformamide and water) based on two ligands, namely, 1,1'-oxy-bis[3,5-diimidazolyl-benzene] (ODIB) and biphenyldicarboxylic acid (H2 bpdc). ODIB ligands link Zn cations to give layers in crystal. bpdc 2- anions coordinate to Zn atoms, however, their introduction does not increase the dimension of the structure. Each layer is partially passes through the adjacent layers in the offset ABAB manner.

  3. Sonochemical synthesis, DNA binding, antimicrobial evaluation and in vitro anticancer activity of three new nano-sized Cu(II), Co(II) and Ni(II) chelates based on tri-dentate NOO imine ligands as precursors for metal oxides.

    PubMed

    Abdel-Rahman, Laila H; Abu-Dief, Ahmed M; El-Khatib, Rafat M; Abdel-Fatah, Shimaa Mahdy

    2016-09-01

    Three new nano sized Cu(II), Co(II) and Ni(II) complexes of imine ligand derived from the condensation of 2-amino-3-hydroxypyridine and 3-methoxysalicylaldehyde have been prepared and investigated using various chemical techniques such as NMR, elemental analysis, molar conductance, IR, electronic spectra, TGA and magnetic moment measurements. The obtained chemical analysis data showed that the synthesis of 1:1 (metal:ligand) ratio and octahedral geometry was proposed on the basis of magnetic moment and spectral data studies except the Cu(II) complex which is tetrahedral geometry. Nano-sized particles of the investigated complexes were prepared by sonochemistry method. Furthermore, metal oxides nanoparticles were gained by calcination of the prepared corresponding complexes at 500°C and their structures were characterized by powder x-ray and transmittance electron microscopy. Moreover, the free ligand, its complexes and their metal oxides have been checked in vitro against a number of bacteria and fungi in order to assess their antimicrobial activities. In addition to that, DNA binding of the prepared complexes was tested by many routes such as electronic spectra, viscosity and gel electrophoresis. The results showed that the investigated complexes could bind to DNA via an intercalative mode. The cytotoxicity of the Schiff base complexes on human colon carcinoma cells, (HCT-116 cell line) and Breast carcinoma cells, (MCF-7 cell line) showed potent cytotoxicity effect against growth of carcinoma cells compared to the clinically used Vinblastine standard. PMID:27395793

  4. Synthesis, mass spectral characterization, NMR analyses, and DFT calculations of 1-desoxymaquindox and 4-desoxymaquindox

    NASA Astrophysics Data System (ADS)

    Zhang, Jiaheng; Peng, Qingrong; Zhang, Suxia; Li, Yubo; Li, Songqing; Gao, Haixiang; Zhou, Zhiqiang

    2011-02-01

    Maquindox, 3-methyl-2-acetylquinoxaline-1,4-dioxide, is a quinoxaline-N,N-dioxide used in veterinary medicine as a feed additive. 1-Desoxymaquindox and 4-desoxymaquindox, two novel deoxidized metabolites of maquindox are synthesized from their parent drug. This study deals with the structural and spectral properties of the maquindox metabolites by employing experimental and theoretical methods. The investigation, using ultra-performance liquid chromatography/electrospray ionization quadrupole time-of-flight mass spectrometry, shows independent proof of the structures. Gauge-including atomic orbital NMR chemical shifts are calculated for isomeric quinoxaline metabolite pairs and several different parameters (correlation coefficient, mean absolute error, and corrected mean absolute error) are investigated. Comparison of the experimental and calculated 1H and 13C NMR chemical shifts allows the reliable assignment of the isomeric quinoxaline compound pairs.

  5. Synthesis and spectral characterization of acetophenone thiosemicarbazone—A nonlinear optical material

    NASA Astrophysics Data System (ADS)

    Santhakumari, R.; Ramamurthi, K.; Vasuki, G.; Yamin, Bohari M.; Bhagavannarayana, G.

    2010-08-01

    Acetophenone thiosemicarbazone (APTSC) was synthesized. Solubility of APTSC was determined in ethanol and methanol at different temperatures. Single crystals were grown from ethanol by slow evaporation at room temperature. The grown crystal was subjected to FTIR, Laser-Raman and 1H NMR spectral analyses to confirm the synthesized compound. Thermal properties were investigated by thermogravimetric and differential thermal analyses. High-resolution X-ray diffractometry (HRXRD) was employed to evaluate the perfection of the grown crystal. The range and percentage of optical transmission was ascertained by recording UV-vis-NIR spectrum. The third order nonlinear optical parameters (nonlinear refractive index and nonlinear absorption coefficient) were derived by the Z-scan technique.

  6. Synthesis and spectral characterization of acetophenone thiosemicarbazone--a nonlinear optical material.

    PubMed

    Santhakumari, R; Ramamurthi, K; Vasuki, G; Yamin, Bohari M; Bhagavannarayana, G

    2010-08-01

    Acetophenone thiosemicarbazone (APTSC) was synthesized. Solubility of APTSC was determined in ethanol and methanol at different temperatures. Single crystals were grown from ethanol by slow evaporation at room temperature. The grown crystal was subjected to FTIR, Laser-Raman and (1)H NMR spectral analyses to confirm the synthesized compound. Thermal properties were investigated by thermogravimetric and differential thermal analyses. High-resolution X-ray diffractometry (HRXRD) was employed to evaluate the perfection of the grown crystal. The range and percentage of optical transmission was ascertained by recording UV-vis-NIR spectrum. The third order nonlinear optical parameters (nonlinear refractive index and nonlinear absorption coefficient) were derived by the Z-scan technique. PMID:20434945

  7. Spectral observations of active region sources with RATAN-600 and WSRT. [Westerbork Synthesis Radio Telescope

    NASA Technical Reports Server (NTRS)

    Alissandrakis, C. E.; Gel'frejkh, G. B.; Borovik, V. N.; Korzhavin, A. N.; Bogod, V. M.; Nindos, A.; Kundu, M. R.

    1993-01-01

    We present spectral observations of neutral line and sunspot associated sources obtained with the RATAN-600 radio telescope and the WSRT in the wavelength range of 2 to 6 cm. Sources associated with large sunspots have flat spectra, while neutral line sources have very steep spectra. In the case of a large spot we estimated the magnetic field to be at least 2700 G at the base of the transition region and 1800 G in the low corona. We consider possible interpretations of the radio emission above the neutral lines. Gyroresonance emission at the fourth harmonic is inadequate, whereas emission from a small population of nonthermal electrons (total number 10 exp 30 to 10 exp 31) with a delta = 3 power law distribution seems to be sufficient.

  8. On the synthesis of sample volumes for real-time spectral Doppler ultrasound simulation.

    PubMed

    Aguilar, Luis A; Steinman, David A; Cobbold, Richard S C

    2010-12-01

    A variety of methods for simulating the ultrasound field produced by transducers are currently used in ultrasound imaging system design. However, simulations can be time-consuming, making them difficult to apply in real-time environments when the observation field changes rapidly with time. This is particularly true for interactive real-time Doppler and B-mode ultrasound simulators designed for use as training tools. In this paper, it is demonstrated that the use of a distribution of monopole sources can be used to simulate the field from a phased linear array and the accuracy should be sufficient for simulating pulsed spectral Doppler. Very good agreement can be achieved in comparison with that obtained by a more exact method and, because of the simplicity of the calculations, real-time simulations of flow in the arterial system becomes possible. Specifically, quantitative measurements were made and compared against an analytic solution for the case of a piston transducer and against Field II for the phased array. The root-mean-square error shows that it is possible to achieve 10% or less error for the latter case. For comparable conditions, the computational speed for the transmit field of phased array using the Field II method as compared with the monopole approach was found to be at least an order of magnitude faster. It is pointed out that the simplicity of the monopole approach provides the opportunity for a further order of magnitude gain. Our findings can have direct application on the simulation of spectral Doppler and other ultrasound techniques for the purpose of teaching and training. PMID:20950935

  9. Opuntia ficus indica peel derived pectin mediated hydroxyapatite nanoparticles: synthesis, spectral characterization, biological and antimicrobial activities.

    PubMed

    Gopi, D; Kanimozhi, K; Kavitha, L

    2015-04-15

    In the present study, we have adapted a facile and efficient green route for the synthesis of HAP nanoparticles using pectin as a template which was extracted from the peel of prickly pear (Opuntia ficus indica) fruits. The concentration of pectin plays a major role in the behavior of crystallinity, purity, morphology as well as biological property of the as-synthesized HAP nanoparticles. The extracted pectin and the as-synthesized nanoparticles were characterized by various analytical techniques. The in vitro apatite formation on the surface of the as-synthesized nanoparticles in simulated body fluid (SBF) for various days showed an enhanced bioactivity. Also, the antimicrobial activity was investigated using various microorganisms. All the results revealed the formation of pure, low crystalline and discrete granular like HAP nanoparticles of size around 25 nm with enhanced biological and antimicrobial activities. Hence the as-synthesized nanoparticles can act as a better bone regenerating material in the field of biomedicine. PMID:25668694

  10. Green synthesis and spectral characterization of silver nanoparticles from Lakshmi tulasi (Ocimum sanctum) leaf extract.

    PubMed

    Subba Rao, Y; Kotakadi, Venkata S; Prasad, T N V K V; Reddy, A V; Sai Gopal, D V R

    2013-02-15

    A simple method for the green synthesis of silver nanoparticles (AgNPs) using aqueous extract of Lakshmi tulasi (Ocimum sanctum) leaf as a reducing and stabilizing agent. AgNPs were rapidly synthesized using aqueous extract of tulasi leaf with AgNO(3) solution within 15 min. The green synthesized AgNPs were characterized using physic-chemical techniques viz., UV-Vis, X-ray diffraction (XRD), scanning electron microscope (SEM) coupled with X-ray energy dispersive spectroscopy (EDX) and Fourier transform-infrared spectroscopy (FT-IR). Characterization data reveals that the particles were crystalline in nature and triangle shaped with an average size of 42 nm. The zeta potential of AgNPs were found to be -55.0 mV. This large negative zeta potential value indicates repulsion among AgNPs and their dispersion stability. PMID:23257344

  11. Green synthesis and spectral characterization of silver nanoparticles from Lakshmi tulasi (Ocimum sanctum) leaf extract

    NASA Astrophysics Data System (ADS)

    Subba Rao, Y.; Kotakadi, Venkata S.; Prasad, T. N. V. K. V.; Reddy, A. V.; Sai Gopal, D. V. R.

    2013-02-01

    A simple method for the green synthesis of silver nanoparticles (AgNPs) using aqueous extract of Lakshmi tulasi (Ocimum sanctum) leaf as a reducing and stabilizing agent. AgNPs were rapidly synthesized using aqueous extract of tulasi leaf with AgNO3 solution within 15 min. The green synthesized AgNPs were characterized using physic-chemical techniques viz., UV-Vis, X-ray diffraction (XRD), scanning electron microscope (SEM) coupled with X-ray energy dispersive spectroscopy (EDX) and Fourier transform-infrared spectroscopy (FT-IR). Characterization data reveals that the particles were crystalline in nature and triangle shaped with an average size of 42 nm. The zeta potential of AgNPs were found to be -55.0 mV. This large negative zeta potential value indicates repulsion among AgNPs and their dispersion stability.

  12. Opuntia ficus indica peel derived pectin mediated hydroxyapatite nanoparticles: Synthesis, spectral characterization, biological and antimicrobial activities

    NASA Astrophysics Data System (ADS)

    Gopi, D.; Kanimozhi, K.; Kavitha, L.

    2015-04-01

    In the present study, we have adapted a facile and efficient green route for the synthesis of HAP nanoparticles using pectin as a template which was extracted from the peel of prickly pear (Opuntia ficus indica) fruits. The concentration of pectin plays a major role in the behavior of crystallinity, purity, morphology as well as biological property of the as-synthesized HAP nanoparticles. The extracted pectin and the as-synthesized nanoparticles were characterized by various analytical techniques. The in vitro apatite formation on the surface of the as-synthesized nanoparticles in simulated body fluid (SBF) for various days showed an enhanced bioactivity. Also, the antimicrobial activity was investigated using various microorganisms. All the results revealed the formation of pure, low crystalline and discrete granular like HAP nanoparticles of size around 25 nm with enhanced biological and antimicrobial activities. Hence the as-synthesized nanoparticles can act as a better bone regenerating material in the field of biomedicine.

  13. Synthesis of imidazole derivatives and the spectral characterization of the binding properties towards human serum albumin

    NASA Astrophysics Data System (ADS)

    Yue, Yuanyuan; Dong, Qiao; Zhang, Yajie; Li, Xiaoge; Yan, Xuyang; Sun, Yahui; Liu, Jianming

    2016-01-01

    Small molecular drugs that can combine with target proteins specifically, and then block relative signal pathway, finally obtain the purpose of treatment. For this reason, the synthesis of novel imidazole derivatives was described and this study explored the details of imidazole derivatives binding to human serum albumin (HSA). The data of steady-state and time-resolved fluorescence showed that the conjugation of imidazole derivatives with HSA yielded quenching by a static mechanism. Meanwhile, the number of binding sites, the binding constants, and the thermodynamic parameters were also measured; the raw data indicated that imidazole derivatives could spontaneously bind with HSA through hydrophobic interactions and hydrogen bonds which agreed well with the results from the molecular modeling study. Competitive binding experiments confirmed the location of binding. Furthermore, alteration of the secondary structure of HSA in the presence of the imidazole derivatives was tested.

  14. Synthesis, structure information, DNA/BSA binding affinity and in vitro cytotoxic studies of mixed ligand copper(II) complexes containing a phenylalanine derivative and diimine co-ligands.

    PubMed

    Annaraj, B; Balakrishnan, C; Neelakantan, M A

    2016-07-01

    Binary [Cu(PAIC)(H2O)2]·H2O (1) and mixed ligand [Cu(PAIC)(L)]·2H2O complexes, where PAIC=phenylalanine imidazole carboxylic acid, L=diimine coligands [2,2'-bipyridine (bpy) (2) and 1,10-phenanthroline (phen) (3)] have been synthesized and fully characterized by analytical and spectral techniques. The X-ray structure of [Cu(PAIC)(phen)]·2H2O (3) shows a N4O coordination with square pyramidal geometry around the copper (II) atom. The spin Hamiltonian parameters calculated for the complexes account for the distorted square planar structure and rules out the possibility of a trigonal bipyramidal structure. Interaction of the complexes (1-3) with calf thymus DNA (CT DNA) was studied by using different techniques (absorption titration, fluorescence quenching and thermal melting) and the studies suggest that these complexes bind to CT DNA through intercalation. The DNA-binding affinity of the complexes has further been explained by DFT computational results. Binding activity of Bovine serum albumin (BSA) reveals that the complexes can strongly quench the intrinsic fluorescence of BSA through a static quenching mechanism. DNA cleavage experiments using plasmid DNA pUC 19 show that the complexes exhibit efficient chemical nuclease activity even in the absence of any external additives. The cytotoxicity of the complexes against human normal cell line (HBL 100) and human breast cancer cell line (MCF-7) shows that metal complexation of the ligands results in a significant enhancement in the cell death of MCF-7. Finally, docking studies on DNA and protein binding interactions were performed. PMID:27155593

  15. Stoichiometry of the heparin-Cu2+-glycine mixed-ligand complex according to differential thermal analysis and IR spectroscopy data

    NASA Astrophysics Data System (ADS)

    Feofanova, M. A.; Frantseva, Yu. V.; Zhuravlev, E. V.; Baranova, N. V.; Ryasenskii, S. S.

    2015-02-01

    A method or the synthesis, isolation, and purification of a mixed-ligand complex of heparin with copper and glycine cations was suggested. The complex was studied by elemental, thermal, and spectral analyses. The elemental and crystalline hydrate compositions of the complex were determined and the molecular formula was suggested to be Na3CuHepGly · 2H2O.

  16. Dinuclear Zinc (II) Complexes of Macrocyclic Polyamine Ligands Containing an Imidazolium Bridge: Synthesis, Characterization, and Their Interaction with Plasmid DNA

    PubMed Central

    Huang, Jun; Huang, Qing-Dong; Zhang, Ji; Zhou, Li-Hong; Li, Qiang-Lin; Li, Kun; Jiang, Ning; Lin, Hong-Hui; Wu, Jiang; Yu, Xiao-Qi

    2007-01-01

    Two novel macrocyclic polyamine ligands and their dinuclear zinc (II) complexes were synthesized and characterized. Their interaction with plasmid DNA was studied by gel electrophoresis and fluorescence quenching experiment. The result showed that these complexes could bind DNA efficiently under physiological conditions.

  17. A Hexakis Terpyridine-Fullerene Ligand in Six-Fold Ruthenium, Iridium, and Iron Complexes: Synthesis and Electrochemical Properties.

    PubMed

    Yan, Weibo; Réthoré, Céline; Menning, Sebastian; Brenner-Weiß, Gerald; Muller, Thierry; Pierrat, Philippe; Bräse, Stefan

    2016-08-01

    An unprecedented straightforward route to six-fold terpyridine ligands around C60 , the latter being regioselectively functionalized in pseudo-octahedral positions using a six-fold Bingel reaction, is reported. Ruthenium, iridium, and iron complexes have been synthesized, and unambiguously characterized by NMR, MS, and cyclic voltammetry. PMID:27189254

  18. A 3D porous zinc MOF constructed from a flexible tripodal ligand: Synthesis, structure, and photoluminescence property

    SciTech Connect

    Wen Lili; Wang Dong'e; Wang Chenggang; Wang Feng; Li Dongfeng Deng Kejian

    2009-03-15

    A new metal-organic framework, [Zn{sub 5}(trencba){sub 2}(OH){sub 2}Cl{sub 2}.4H{sub 2}O] (1) [H{sub 3}trencba=N,N,N',N',N'',N''-tris[(4-carboxylate-2-yl)methyl]-tris (2-aminoethyl)amine], constructed from a flexible tripodal ligand based on C{sub 3} symmetric tris(2-aminoethyl)amine, has been synthesized hydrothermally and characterized by elemental analysis, IR, TG, XRD and single-crystal X-ray diffraction analysis. Compound 1 contains an unprecedented linear penta-nuclear zinc cluster fragment. Each ligand links four penta-nuclear fragments, and every fragment links eight ligands to generate a three-dimensional non-interpenetrated porous framework. The uncoordinated water molecules were observed trapped in the void pores. Compound 1 represents the first example of (6,8)-connected 3D bi-nodal framework based on a single kind of organic ligand. The photoluminescence measurements showed that complex 1 exhibits relatively stronger blue emissions at room temperature than that of the ligand. - Graphical abstract: The MOF [Zn{sub 5}(trencba){sub 2}(OH){sub 2}Cl{sub 2}.4H{sub 2}O] (H{sub 3}trencba=N,N,N',N',N',N'-tris[(4-carboxylate-2-yl)methyl]-tris (2-aminoethyl)amine) reveals a (6,8)-connected bi-nodal three-dimensional porous framework with unprecedented penta-nuclear fragment, which appears to be a good candidate of hybrid inorganic-organic photoactive materials.

  19. [18F]Fluoroalkyl agents: synthesis, reactivity and application for development of PET ligands in molecular imaging.

    PubMed

    Zhang, Ming-Rong; Suzuki, Kazutoshi

    2007-01-01

    Fluorine-18 ((18)F, beta(+); 96.7%, T(1/2)=109.8 min) is of considerable importance for developing positron emission tomography (PET) ligands for imaging receptor, enzyme, gene expression etc. in brain, tumor, myocardium and other regions or organs due to its optimal decay characteristics. To synthesize (18)F-labeled PET ligands, reliable labeling techniques inserting (18)F into a target molecule are necessary. [(18)F]Fluoroalkylation is a useful way of introducing (18)F into target molecules containing amino, phenol, thiophenol, and amide functional groups. Here, we review the preparation, reactivity and application of [(18)F]fluoroalkyl agents for the development of (18)F-labeled PET ligands in molecular imaging. [(18)F]Fluoroalkyl agents have been synthesized by reacting [(18)F]F(-) with the corresponding alkyl derivatives containing halogen and sulfonate as leaving groups. After the fluorination reaction, the radiolabeled products with relatively low boiling points were distilled from the reaction mixtures, sometimes added by Sep-Pak or gas chromatography separation. The [(18)F]fluoromethyl agents have high reactivity with nucleophilic substrates, but many [(18)F]fluoromethylated compounds are in vitro unstable. To increase the efficiency of [(18)F]fluoroethylation, [(18)F]FCH2CH2Br, the most frequently used [(18)F]fluoroethyl agent, was converted into [(18)F]FCH2CH2I or [(18)F]FCH2CH2OTf in situ. Most [(18)F]fluoromethylated ligands were found to be in vivo unstable due to defluorination. Deuterium substitution for the fluoromethyl group reduced defluorination to an extent. A number of [(18)F]fluoroethylated PET ligands have been developed for animal evaluation and clinical investigation. PMID:17979790

  20. Ruthenium(II) arene complexes with chelating chloroquine analogue ligands: Synthesis, characterization and in vitro antimalarial activity†

    PubMed Central

    Glans, Lotta; Ehnbom, Andreas; de Kock, Carmen; Martínez, Alberto; Estrada, Jesús; Smith, Peter J.; Haukka, Matti; Sánchez-Delgado, Roberto A.; Nordlander, Ebbe

    2012-01-01

    Three new ruthenium complexes with bidentate chloroquine analogue ligands, [Ru(η6-cym)(L1)Cl]Cl (1, cym = p-cymene, L1 = N-(2-((pyridin-2-yl)methylamino)ethyl)-7-chloroquinolin-4-amine), [Ru(η6-cym)(L2)Cl]Cl (2, L2 = N-(2-((1-methyl-1H-imidazol-2-yl)methylamino)ethyl)-7-chloroquinolin-4-amine) and [Ru(η6-cym)(L3)Cl] (3, L3 = N-(2-((2-hydroxyphenyl)methylimino)ethyl)-7-chloroquinolin-4-amine) have been synthesized and characterized. In addition, the X-ray crystal structure of 2 is reported. The antimalarial activity of complexes 1–3 and ligands L1, L2 and L3, as well as the compound N-(2-(bis((pyridin-2-yl)methyl)amino)ethyl)-7-chloroquinolin-4-amine (L4), against chloroquine sensitive and chloroquine resistant Plasmodium falciparum malaria strains was evaluated. While 1 and 2 are less active than the corresponding ligands, 3 exhibits high antimalarial activity. The chloroquine analogue L2 also shows good activity against both the choloroquine sensitive and the chloroquine resistant strains. Heme aggregation inhibition activity (HAIA) at an aqueous buffer/n-octanol interface (HAIR50) and lipophilicity (D, as measured by water/n-octanol distribution coefficients) have been measured for all ligands and metal complexes. A direct correlation between the D and HAIR50 properties cannot be made because of the relative structural diversity of the complexes, but it may be noted that these properties are enhanced upon complexation of the inactive ligand L3 to ruthenium, to give a metal complex (3) with promising antimalarial activity. PMID:22249579

  1. Herbo-mineral based Schiff base ligand and its metal complexes: Synthesis, characterization, catalytic potential and biological applications.

    PubMed

    Kareem, Abdul; Laxmi; Arshad, Mohammad; Nami, Shahab A A; Nishat, Nahid

    2016-07-01

    Schiff base ligand, (L), derived from condensation reaction of 1,7-bis-(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione, (curcumin), with pyridine-3-carboxamide, (nicotinamide), and its complexes of Co(II), Ni(II) and Cu(II) ions, containing 1,10-phenanthroline as auxiliary ligand were synthesized and characterized by various physico-chemical techniques. From the micro analytical data, the stoichiometry of the complexes 1:1 (metal: ligand) was ascertained. The Co(II) and Cu(II) forms octahedral complexes, while the geometric structure around Ni(II) atom can be described as square planar. The catalytic potential of the metal complexes have been evaluated by recording the rate of decomposition of hydrogen peroxide. The results reveal that the percent decomposition of H2O2increases with time and the highest value (50.50%) was recorded for Co(II) complex. The ligand and its complexes were also screened for their in vitro antibacterial activity against Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, Streptococcus pyogenes and Pseudomonas aeruginosa. The relative order of antibacterial activity against S. Pyogenes, S. aureus and E. coli is Cu(II)>Ni(II)>Co(II)>(L); while with P. aeruginosa, K. pneumoniae the order of activity is Cu(II)>Co(II)>Ni(II)>(L). The anthelmintic screening was performed using Pheretima posthuma. The order of anthelmintic activity of ligand and its complexes is [(Phen)CuLCl2]>[(Phen)CoLCl2]>[(Phen)NiL]Cl2>(L). PMID:27107703

  2. [Controllable synthesis and UV-Vis spectral analysis of silver nanoparticles in AOT microemulsion].

    PubMed

    Zhang, Wan-Zhong; Qiao, Xue-Liang; Luo, Lang-Li; Chen, Jian-Guo

    2009-03-01

    Colloidal silver nanoparticles were synthesized in water-in-oil microemulsion using silver nitrate solubilized in the water core of a microemulsion as source of silver ions, hydrazine hydrate solubilized in the water core of another one as reducing agent, cyclohexane as the continuous phase, and sodium bis(2-ethylhexyl) sulfosuccinate (AOT) as the surfactant. The main factors affecting the formation of silver nanoparticles were systematically studied. Ultraviolet-visible (UV-Vis) spectra were used for analyzing the effects of reaction parameters, including the type of reducing agents, the molar ratio of water to surfactant and the concentration of AgNO3 and AOT and so on, on the formation of silver nanoparticles. Original results for the controllable synthesis of silver nanoparticles were obtained when the synthesis proceeded in AOT-cyclohexane-AgNO3 microemulsion. The UV-Vis spectra of silver sols formed in the microemulsion with various parameters were studied systematically. The results show that the amount and average size of the obtained nanoparticles obviously depend on the above parameters. When the concentration of AgNO3 is lower, smaller silver nanoparticles are easy to form by increasing the concentration of AgNO3 appropriately. The higher W value was found to form larger numbers of silver nanoparticles with larger particle size. Compared to the solubility of NaBH4 in AOT reverse micelles, hydrazine hydrate is well soluble in these micelles, and thus it is favorable to reduce the silver ions solubilized in the water core of AOT-cyclohexane-AgNO3 microemulsion. The increase in the concentration of AOT induces an increase in the number of AOT micelles and a decrease in the molar ratio of water to surfactant. As a result, the solubilization capacity of reactants in the micelles increases and the radii of the micelles decrease. That is to say, with the increase in AOT concentration, the amount of the formed nanoparticles increases and the average size of the

  3. Synthesis and characterization of a three dimensional zinc(II) metal-organic framework constructed from flexible 1,2,3,4-tetra-(4-pyridyl)-butane ligand

    NASA Astrophysics Data System (ADS)

    Lin, Jianguo; Wu, Peiheng; Kang, Lin; Lu, Changsheng; Meng, Qingjin

    2011-08-01

    Employing the flexible tetrapodal ligand 1,2,3,4-tetra-(4-pyridyl)-butane (TPB) along with fumaric acid (H 2FMA) as the bridges, a metal-organic framework of [Zn(TPB)(FMA)·(2H 2O)] ( 1) was obtained and characterized by elemental analysis, spectral method (IR), single crystal X-ray diffraction, thermal gravimetric analysis (TGA) and fluorescent property. This polymer exhibits a three dimensional (3D) dense network with an interesting (4,4)-connected PtS topology. It also displays good thermal stability and strong photoluminescence in the blue region band. Thus it may serve as a candidate of thermally stable blue-light-emitting photoluminescent material.

  4. Mononuclear Ru(III) Schiff base complexes: Synthesis, spectral, redox, catalytic and biological activity studies

    NASA Astrophysics Data System (ADS)

    Priya, N. Padma; Arunachalam, S.; Manimaran, A.; Muthupriya, D.; Jayabalakrishnan, C.

    2009-04-01

    An octahedral ruthenium(III) Schiff base complexes of the type [RuX(EPh 3)(L)] (where, X = Cl/Br; E = As/P; L = dianion of the Schiff bases derived from acetoacetanilide with o-phenylenediamine and salicylaldehyde/ o-hydroxyacetophenone/ o-vanillin/2-hydroxy-1-naphthaldehyde) have been synthesized from the reactions of equimolar reactions of [RuX 3(EPh 3) 3] and Schiff bases in benzene. The new Ru(III) Schiff base complexes have been characterized by elemental analyses, FT-IR, electronic, 1H NMR and 13C NMR spectra, EPR spectral studies, powder X-ray diffraction (XRD) and electrochemical studies. The new complexes were found to be effective catalysts for aryl-aryl coupling and the oxidation of alcohols into their corresponding carbonyl compounds, respectively, using molecular oxygen atmosphere at ambient temperature. Further, the new Ru(III) Schiff base complexes were screened for their antibacterial activity against Pseudomonas aeruginosa, Vibrio cholera, Salomonella typhi and Staphylococcus aureaus.

  5. Synthesis, spectral characterization and larvicidal activity of acridin-1(2H)-one analogues

    NASA Astrophysics Data System (ADS)

    Subashini, R.; Bharathi, A.; Roopan, Selvaraj Mohana; Rajakumar, G.; Abdul Rahuman, A.; Gullanki, Pavan Kumar

    Acridin-1(2H)-one analogue of 7-chloro-3,4-dihydro-9-phenyl-2-[(pyridine-2yl) methylene] acridin-1(2H)-one, 5 was prepared by using 7-chloro-3,4-dihydro-9-phenylacridin-1(2H)-one, 3 and picolinaldehyde, 4 in the presence of KOH at room temperature. These compounds were characterized by analytical and spectral analyses. The purpose of the present study was to assess the efficacy of larvicidal and repellent activity of synthesized 7-chloro-3,4-dihydro-9-phenyl-acridin-1(2H)-one analogues such as compounds 3 and 5 against the early fourth instar larvae of filariasis vector, Culex quinquefasciatus and Japanese encephalitis vector, Culex gelidus (Diptera: Culicidae). The compound exhibited high larvicidal effects at 50 mg/L against both the mosquitoes with LC50 values of 25.02 mg/L (r2 = 0.998) and 26.40 mg/L (r2 = 0.988) against C. quinquefasciatus and C. gelidus, respectively. The 7-chloro-3,4-dihydro-9-phenyl-acridin-1(2H)-one analogues that are reported for the first time to our best of knowledge can be better explored for the control of mosquito population. This is an ideal ecofriendly approach for the control of Japanese encephalitis vectors, C. quinquefasciatus and C. gelidus.

  6. [Synthesis and spectral characteristic of Ga-Fe3O4 at room temperature].

    PubMed

    Wang, Jing; Deng, Tong; Yang, Cai-Qin; Lin, Yu-Long; Wang, Wei; Wu, Hai-Yan

    2008-03-01

    Gallium bearing ferrites with different gallium content were synthesized by oxidation of ferrous and gallium ions under alkaline condition and room temperature. The samples were subjected to IR, XRD, Mossbauer spectral analysis and magnetization characterization. The results indicated that the green-rust intermediate phase would be produced during the procedure of Ga-Fe3O4 formation, and the green-rust intermediate phase was converted to ferrites with spinel structure during the drying under hot-N2 atmosphere. With the introduction of gallium into the spinel structure, the interplanar crystal spacing of the spinel structure decreased, as indicated from XRD spectra, and the lattice vibration of M(T)-O-M(o) moved to the high-frequency resulting from IR spectra. A small amount gallium introduction entered the tetrahedral sites preferentially rather than the octahedral sites, and increasing gallium introduction would enhance the occupation of octahedral sites. Furthermore, a small content of gallium in the initial solution could prevent the formation of non-magnetic Fe2O3. PMID:18536451

  7. Ultraviolet Spectral Synthesis and Oxygen in Metal-Poor Solar-Type Stars

    NASA Astrophysics Data System (ADS)

    Peterson, R. C.

    1999-05-01

    This report outlines the progress and pitfalls of calculating spectra from first principles in the 2300 -- 3400A region for metal-poor solar-type stars, and how they relate to the derivation of abundances of key species such as oxygen and magnesium. This work is part of a NASA-supported effort with Ben Dorman of Goddard Space Flight Center to develop ab initio spectra suitable for galaxy analysis, and also part of a HST-oriented program with Karel Schrijver of Lockheed Martin to characterize the chromospheric activity of the oldest solar-type stars. The first task has been a reanalysis of the basic stellar parameters of temperature, surface gravity, and metallicity for solar-temperature stars ranging from one-fifth to one-three hundredth solar metallicity, demanding agreement in line strengths and profiles of strong lines and weak, in both optical and ultraviolet, and in the ultraviolet flux distribution. These cross-checks are built in to ensure convergence to a unique solution, or to highlight where standard assumptions are breaking down. Once agreement is achieved for the most metal-deficient stars, the line list used for the spectral calculations is re-examined, and somewhat more metal-rich stars are matched. Abundance results for oxygen from various approaches will be described, from the near-UV OH, 6300A [O I], and near-IR O I lines, and from adopting laboratory versus theoretical versus astrophysical atomic and molecular constants.

  8. Synthesis and spectral characterization of Zn(II) microsphere series for antimicrobial application

    NASA Astrophysics Data System (ADS)

    Singh, Ajay K.; Pandey, Sarvesh K.; Pandey, O. P.; Sengupta, S. K.

    2014-09-01

    Microsphere series have been synthesized by reacting zinc(II) acetate dihydrate with Schiff bases derived from 2-hydrazino-5-[substituted phenyl]-1,3,4-thiadiazole/oxadiazole/triazole with salicylaldehyde. Elemental analysis suggests that the complexes have 1:2 and 1:1 stoichiometry of the type [Zn(L)2(H2O)2] and [Zn(L‧)(H2O)2]; LH = Schiff bases derived from 2-hydrazino-5-[substituted phenyl]-1,3,4-thia/oxadiazole with salicylaldehyde; L‧H2 = Schiff bases derived from 3-(substituted phenyl)-4-amino-5-hydrazino-1,2,4-triazole and salicylaldehyde and were characterized by elemental analyses, IR, 1H NMR and 13C NMR spectral data. Scanning electron microscopy (SEM) showed that synthesized materials have microsphere like structure and there EDX analysis comparably matches with elemental analysis. For the antimicrobial application Schiff bases and their zinc(II) complexes were screened for four bacteria e.g. Bacillus subtilis, Pseudomonas aeruginosa, Salmonella typhi, Streptococcus pyogenes and four fungi e.g. Cyrtomium falcatum, Aspergillus niger, Fusarium oxysporium and Curvularia pallescence by the reported method. Schiff base and Zn(II) compounds showed significant antimicrobial activities. However, activities increase upon chelation. Thermal analysis (TGA) data of compound (10) showed its stability up to 300 °C.

  9. A 4-(o-chlorophenyl)-2-aminothiazole: Microwave assisted synthesis, spectral, thermal, XRD and biological studies

    NASA Astrophysics Data System (ADS)

    Rajmane, S. V.; Ubale, V. P.; Lawand, A. S.; Nalawade, A. M.; Karale, N. N.; More, P. G.

    2013-11-01

    A 4-(o-chlorophenyl)-2-aminothiazole (CPAT) has been synthesized by reacting o-chloroacetophenone, iodine and thiourea under microwave irradiation as a green chemistry approach. The reactions proceed selectively and within a couple of minutes giving high yields of the products. The compound was characterized by elemental, spectral (UV-visible, IR, NMR and GC-MS), XRD and thermal analyses. The TG curve of the compound was analyzed to calculate various kinetic parameters (n, E, Z, ΔS and ΔG) by using Coats-Redfern (C.R.), MacCallum-Tanner (M.T.) and Horowitz-Metzger (H.M.) method. The compound was tested for the evaluation of antibacterial activity against B. subtilis and E. coli and antifungal activity against A. niger and C. albicans. The compound was evaluated for their in vitro nematicidal activity on plant parasitic nematode Meloidogyne javanica and molluscicidal activity on fresh water helminthiasis vector snail Lymnea auricularia. The compound is biologically active in very low concentration. X-ray diffraction study suggests a triclinic crystal system for the compound.

  10. Synthesis, biological and comparative DFT studies on Ni(II) complexes of NO and NOS donor ligands.

    PubMed

    Yousef, T A; El-Gammal, O A; Ahmed, Sara F; Abu El-Reash, G M

    2015-01-25

    Three new NOS donor ligands have been prepared by addition ethanolic suspension of 2-hydrazino-2-oxo-N-phenyl-acetamide to phenyl isocyanate (H2PAPS), phenyl isothiocyanate (H2PAPT) and benzoyl isothiocyanate (H2PABT). The Ni(II) complexes prepared from the chloride salt and characterized by conventional techniques. The isolated complexes were assigned the formulaes, [Ni2(PAPS)(H2O)2](H2O)2, [Ni(H2PAPT)Cl2(H2O)](H2O)2 and [(Ni)2(HPABT)2Cl2(H2O)2], respectively. The IR spectra of complexes shows that H2PAPS behaves as a binegative pentadentate via both CO of hydrazide moiety in keto and enol form, enolized CO of cyanate moiety and the CN (azomethine) groups of enolization. H2PAPT behaves as neutral tridentate via both CO of hydrazide moiety and CN (azomethine) group due to SH formation and finally H2PABT behaves as mononegative tetradentate via CO and enolized CO of hydrazide moiety, CO of benzoyl moiety and C=S groups. The experimental IR spectra of ligands are compared with those obtained theoretically from DFT calculations. Also, the bond lengths, bond angles, HOMO (Highest Occupied Molecular Orbitals), LUMO (Lowest Unoccupied Molecular Orbital) and dipole moments have been calculated. The calculated HOMO-LUMO energy gap reveals that charge transfer occurs within the molecule. The theoretical values of binding energies indicate the higher stability of complexes than of ligands. Also, the kinetic and thermodynamic parameters for the different thermal degradation steps of the complexes were determined by Coats-Redfern and Horowitz-Metzger methods. The antibacterial activities were also tested against B. Subtilis and E. coli bacteria. The free ligands showed a higher antibacterial effect than their Ni(II) complexes. The antitumor activities of the Ligands and their Ni(II) complexes have been evaluated against liver (HePG2) and breast (MCF-7) cancer cells. All ligands were found to display cytotoxicity that are better than that of Fluorouracil (5-FU), while Ni

  11. Synthesis, biological and comparative DFT studies on Ni(II) complexes of NO and NOS donor ligands

    NASA Astrophysics Data System (ADS)

    Yousef, T. A.; El-Gammal, O. A.; Ahmed, Sara F.; Abu El-Reash, G. M.

    2015-01-01

    Three new NOS donor ligands have been prepared by addition ethanolic suspension of 2-hydrazino-2-oxo-N-phenyl-acetamide to phenyl isocyanate (H2PAPS), phenyl isothiocyanate (H2PAPT) and benzoyl isothiocyanate (H2PABT). The Ni(II) complexes prepared from the chloride salt and characterized by conventional techniques. The isolated complexes were assigned the formulaes, [Ni2(PAPS)(H2O)2](H2O)2, [Ni(H2PAPT)Cl2(H2O)](H2O)2 and [(Ni)2(HPABT)2Cl2(H2O)2], respectively. The IR spectra of complexes shows that H2PAPS behaves as a binegative pentadentate via both CO of hydrazide moiety in keto and enol form, enolized CO of cyanate moiety and the CN (azomethine) groups of enolization. H2PAPT behaves as neutral tridentate via both CO of hydrazide moiety and CN (azomethine) group due to SH formation and finally H2PABT behaves as mononegative tetradentate via CO and enolized CO of hydrazide moiety, CO of benzoyl moiety and Cdbnd S groups. The experimental IR spectra of ligands are compared with those obtained theoretically from DFT calculations. Also, the bond lengths, bond angles, HOMO (Highest Occupied Molecular Orbitals), LUMO (Lowest Unoccupied Molecular Orbital) and dipole moments have been calculated. The calculated HOMO-LUMO energy gap reveals that charge transfer occurs within the molecule. The theoretical values of binding energies indicate the higher stability of complexes than of ligands. Also, the kinetic and thermodynamic parameters for the different thermal degradation steps of the complexes were determined by Coats-Redfern and Horowitz-Metzger methods. The antibacterial activities were also tested against B. Subtilis and E. coli bacteria. The free ligands showed a higher antibacterial effect than their Ni(II) complexes. The antitumor activities of the Ligands and their Ni(II) complexes have been evaluated against liver (HePG2) and breast (MCF-7) cancer cells. All ligands were found to display cytotoxicity that are better than that of Fluorouracil (5-FU), while Ni

  12. Green synthesis, characterization and catalytic activity of the Pd/TiO2 nanoparticles for the ligand-free Suzuki-Miyaura coupling reaction.

    PubMed

    Nasrollahzadeh, Mahmoud; Sajadi, S Mohammad

    2016-03-01

    A green synthesis process was developed for production of the Pd/TiO2 nanoparticles (NPs) without using toxic, hazardous and dangerous materials. Myrtus communis L. leaf extract serves as a mild, renewable and non-toxic reducing agent. The advantages of this biosynthesis method include use of cheap, clean, nontoxic and environmentally benign precursors and simple procedures without time-consuming polymerization and problems with treatment of a highly viscous polymeric resin. More importantly, the synthesized Pd/TiO2 NPs presented excellent catalytic activity for ligand-free Suzuki-Miyaura coupling which could be easily separated from the reaction mixture and reused many times with no loss of activity. Therefore, these properties indicate demonstrative benefits of the catalyst. The Pd/TiO2 NPs was characterized by FESEM, TEM, FT-IR, UV-vis spectroscopy and EDS. PMID:26674227

  13. Synthesis and in vitro autoradiographic evaluation of a novel high-affinity radioiodinated ligand for imaging brain cannabinoid subtype-1 receptors.

    PubMed

    Donohue, Sean R; Varnäs, Katarina; Jia, Zhisheng; Gulyás, Balázs; Pike, Victor W; Halldin, Christer

    2009-11-01

    There is strong interest to study the involvement of brain cannabinoid subtype-1 (CB1) receptors in neuropsychiatric disorders with single photon emission computed tomography (SPECT) and a suitable radioligand. Here we report the synthesis of a novel high-affinity radioiodinated CB1 receptor ligand ([125I]8, [125I]1-(2-iodophenyl)-4-cyano-5-(4-methoxyphenyl)-N-(piperidin-1-yl)-1H-pyrazole-3-carboxylate, [125I]SD7015). By autoradiography in vitro, [125I]8 showed selective binding to CB1 receptors on human brain postmortem cryosections and now merits labeling with iodine-123 for further evaluation as a SPECT radioligand in non-human primate. PMID:19767206

  14. Synthesis and characterization of two 1D polymeric zinc(II) azido complexes derived from pyridine-N-oxide co-ligands

    NASA Astrophysics Data System (ADS)

    Mautner, Franz A.; Berger, Christian; Massoud, Salah S.

    2016-04-01

    The synthesis and structural characterization of two new polymeric zinc(II) azido complexes with pyridine-N-oxide derivative co-ligands, namely catena-[Zn(4-methylpyridine-N-oxide)(μ1,1-N3)2] (1) and catena-{[Zn2(μ2-isonicotinato-N-oxide)2(μ1,1-N3)2(H2O)3](H2O)} (2) are reported. Single crystal structure determination revealed the penta-coordinated geometry of the Zn(II) centers in the polymeric chains of 1 with di-EO azido bridging mode, whereas five and six coordination modes around Zn(II) centers are observed in complex 2, and the 1D system is formed via alternating single EO-azide and μ(O,O‧)-bridging carboxylate group of the isonicotinato-N-oxide molecules. The solid state luminescence properties of 1 were examined.

  15. Synthesis, structural characterization, thermal and electrochemical studies of Mn(II), Co(II), Ni(II) and Cu(II) complexes containing thiazolylazo ligands

    NASA Astrophysics Data System (ADS)

    Chavan, S. S.; Sawant, V. A.

    2010-02-01

    Some thiazolylazo derivatives and their metal complexes of the type [M(L)(H 2O)Cl]; M = Mn(II), Co(II), Ni(II), Cu(II) and L = 6-(2'-thiazolylazo)-2-mercapto-quinazolin-4-one (HL 1), 6-(4'-phenyl-2'-thiazolylazo)-2-mercapto-quinazolin-4-one (HL 2), 6-(2'-thiazolylazo)-2-mercapto-3-( m-tolyl)-quinazolin-4-one (HL 3) and 6-(4'-phenyl-2'-thiazolylazo)-2-mercapto-3-( m-tolyl)-quinazolin-4-one (HL 4) have been prepared. All the complexes were characterized on the basis of elemental analysis, molar conductance, magnetic moment, IR, UV-vis, ESR, TG-DTA and powder X-ray diffraction studies. IR spectra of these complexes reveal that the complex formation occurred through thiazole nitrogen, azo nitrogen, imino nitrogen and sulfur atom of the ligands. On the basis of electronic spectral data and magnetic susceptibility measurement octahedral geometry has been proposed for the Mn(II), Co(II) and Ni(II) complexes and distorted octahedral geometry for the Cu(II) complexes. Electrochemical behavior of Ni(II) complexes exhibit quasireversible oxidation corresponding to Ni(III)/Ni(II) couple along with ligand reduction. X-ray diffraction study is used to elucidate the crystal structure of the complexes.

  16. Synthesis, characterization, and antipathogenic studies of some transition metal complexes with N,O-chelating Schiff's base ligand incorporating azo and sulfonamide Moieties

    NASA Astrophysics Data System (ADS)

    Alaghaz, Abdel-Nasser M. A.; Bayoumi, Hoda A.; Ammar, Yousry A.; Aldhlmani, Sharah A.

    2013-03-01

    Chromium(III), Manganese(II), Cobalt(II), nickel(II), copper(II) and cadmium(II) complexes of 4-[4-hydroxy-3-(phenyliminomethyl)-phenylazo]benzenesulfonamide, were prepared and characterized on the basis of elemental analyses, spectral, magnetic, molar conductance and thermal analysis. Square planar, tetrahedral and octahedral geometries have been assigned to the prepared complexes. Dimeric complexes are obtained with 2:2 molar ratio except chromium(III) complex is monomeric which is obtained with 1:1 molar ratios. The IR spectra of the prepared complexes were suggested that the Schiff base ligand(HL) behaves as a bi-dentate ligand through the azomethine nitrogen atom and phenolic oxygen atom. The crystal field splitting, Racah repulsion and nepheloauxetic parameters and determined from the electronic spectra of the complexes. Thermal studies suggest a mechanism for degradation of HL and its metal complexes as function of temperature supporting the chelation modes. Also, the activation thermodynamic parameters, such as ΔE*, ΔH*, ΔS* and ΔG* for the different thermal decomposition steps of HL and its metal complexes were calculated. The pathogenic activities of the synthesized compounds were tested in vitro against the sensitive organisms Staphylococcus aureus (RCMB010027), Staphylococcus epidermidis (RCMB010024) as Gram positive bacteria, Klebsiella pneumonia (RCMB 010093), Shigella flexneri (RCMB 0100542), as Gram negative bacteria and Aspergillus fumigates (RCMB 02564), Aspergillus clavatus (RCMB 02593) and Candida albicans (RCMB05035) as fungus strain, and the results are discussed.

  17. Complexes of cis-dioxomolybdenum(VI) and oxovanadium(IV) with a tridentate ONS donor ligand: synthesis, spectroscopic properties, X-ray crystal structure and catalytic activity.

    PubMed

    Fayed, Ahmed M; Elsayed, Shadia A; El-Hendawy, Ahmed M; Mostafa, Mohamed R

    2014-08-14

    New cis-dioxomolybdenum(VI) and oxovanadium(IV) complexes of the Schiff base, derived from S-methyl dithiocarbazate and 2,3-dihydroxybenzaldehyde (H2dhsm), have been synthesized. The complexes of the type cis-[MoO2(dhsm)] (1a), cis-[MoO2(dhsm)(D)] (1b-1d) [D=neutral monodentate ligand; EtOH, pyridine (py) or imidazole (imz)], [VO(dhsm)(NN)] (2a, 2b) [NN=2,2'-bipyridine (bipy) or 1,10-phenanthroline (phen)] and [VO(dhsm)] (2c) have been isolated, characterized by (1)H NMR, IR, UV-Vis and EPR spectral studies and investigated by cyclic voltammetry. The X-ray crystal structure of cis-[MoO2(dhsm)(EtOH)] (1b) has been determined and shows that the complex has a distorted octahedral geometry in which the H2dhsm behaves as a dianionic ONS tridentate ligand coordinating via phenoxide oxygen, hydrazinic nitrogen and thiolate sulfur. The oxomolybdenum(IV) complex [MoO(dhsm)] (1e) has obtained from dioxomolybdenum(VI) complex (1b) by oxo abstraction with PPh3. The reactivity of the complexes toward catalytic oxidation of alcohols in the presence of H2O2 and t-BuOOH as co-oxidants under solvent free conditions is reported. PMID:24747851

  18. Cr(III), Fe(III) and Co(III) complexes of tetradentate (ONNO) Schiff base ligands: Synthesis, characterization, properties and biological activity

    NASA Astrophysics Data System (ADS)

    Keskioğlu, Eren; Gündüzalp, Ayla Balaban; Çete, Servet; Hamurcu, Fatma; Erk, Birgül

    2008-08-01

    A series of metal complexes were synthesized from equimolar amounts of Schiff bases: 1,4-bis[3-(2-hydroxy-1-naphthaldimine)propyl]piperazine (bappnaf) and 1,8-bis[3-(2-hydroxy-1-naphthaldimine)- p-menthane (damnaf) with metal chlorides. All of synthesized compounds were characterized by elemental analyses, spectral (UV-vis, IR, 1H- 13C NMR, LC-MS) and thermal (TGA-DTA) methods, magnetic and conductance measurements. Schiff base complexes supposed in tetragonal geometry have the general formula [M(bappnaf or damnaf)]Cl· nH 2O, where M = Cr(III), Co(III) and n = 2, 3. But also Fe(III) complexes have octahedral geometry by the coordination of two water molecules and the formula is [Fe(bappnaf or damnaf)(H 2O) 2]Cl. The changes in the selected vibration bands in FT-IR indicate that Schiff bases behave as (ONNO) tetradentate ligands and coordinate to metal ions from two phenolic oxygen atoms and two azomethine nitrogen atoms. Conductance measurements suggest 1:1 electrolytic nature of the metal complexes. The synthesized compounds except bappnaf ligand have the antimicrobial activity against the bacteria: Escherichia coli (ATCC 11230), Yersinia enterocolitica (ATCC 1501), Bacillus magaterium (RSKK 5117), Bacillus subtilis (RSKK 244), Bacillus cereus (RSKK 863) and the fungi: Candida albicans (ATCC 10239). These results have been considerably interest in piperazine derivatives due to their significant applications in antimicrobial studies.

  19. Synthesis, spectral, thermal and biological studies on N(-)(2,4-dinitro-phenyl)-2-mercaptoacetohydrazide and its metal complexes.

    PubMed

    El-Asmy, A A; Rakha, T H; Abdel-Rhman, M H; Hassanien, M M; Al-Mola, A S

    2015-02-01

    Complexes of VO(2+), Cr(3+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+) and Hg(2+) ions with N(-)(2,4-dinitrophenyl)-2-mercaptoacetohydrazide (H2L) have been prepared and characterized on the basis of elemental analysis, molar conductance, thermal (TGA, DTGA), spectral (IR, NMR, UV-Visible, MS) and magnetic measurements. The IR spectra show that H2L behaves in a mononegative and/or binegative bidentate manner. The sulfate bridged the two complex molecules in [Cu(HL)(H2O)2(½SO4)]⋅3H2O. The acetate functions as a monodentate in [Ni(HL)(OAc)(H2O)3] and [Cr(HL)(OAc)2(H2O)(EtOH)]. Different stereochemistries are proposed: octahedral for Cr(III), Ni(II), Hg(II) and [Cu(HL)(H2O)2(SO4)0.5]⋅3H2O, square-based pyramid for [VO(HL)2]⋅EtOH, square-planar for [Co(L)(EtOH)(H2O)]⋅H2O, [Cu(L)(H2O)2] and tetrahedral for [Zn(L)(EtOH)(H2O)], [Cd(L)(EtOH)(H2O)] and [Cu2(HL)(H2O)6]Cl3⋅H2O according to the data of electronic spectra and magnetic measurements. The TGA data support the formula and indicate the outer and inner solvents as well as the final residue. The thermodynamic parameters are calculated using the Coats-Redfern and Horowitz-Metzger methods. H2L and [Zn(L)(EtOH)(H2O)] showed the highest cytotoxic activity while H2L has a higher antioxidant activity than ascorbic acid. The ionization constant of the ligand and the stability constant of the Cu(II)H2L in absence and presence of hexamine buffer were calculated. PMID:25467662

  20. Synthesis, spectral, thermal and biological studies on N-(2,4-dinitro-phenyl)-2-mercaptoacetohydrazide and its metal complexes

    NASA Astrophysics Data System (ADS)

    El-Asmy, A. A.; Rakha, T. H.; Abdel-Rhman, M. H.; Hassanien, M. M.; Al-Mola, A. S.

    2015-02-01

    Complexes of VO2+, Cr3+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+ and Hg2+ ions with N-(2,4-dinitrophenyl)-2-mercaptoacetohydrazide (H2L) have been prepared and characterized on the basis of elemental analysis, molar conductance, thermal (TGA, DTGA), spectral (IR, NMR, UV-Visible, MS) and magnetic measurements. The IR spectra show that H2L behaves in a mononegative and/or binegative bidentate manner. The sulfate bridged the two complex molecules in [Cu(HL)(H2O)2(½SO4)]ṡ3H2O. The acetate functions as a monodentate in [Ni(HL)(OAc)(H2O)3] and [Cr(HL)(OAc)2(H2O)(EtOH)]. Different stereochemistries are proposed: octahedral for Cr(III), Ni(II), Hg(II) and [Cu(HL)(H2O)2(SO4)0.5]ṡ3H2O, square-based pyramid for [VO(HL)2]ṡEtOH, square-planar for [Co(L)(EtOH)(H2O)]ṡH2O, [Cu(L)(H2O)2] and tetrahedral for [Zn(L)(EtOH)(H2O)], [Cd(L)(EtOH)(H2O)] and [Cu2(HL)(H2O)6]Cl3ṡH2O according to the data of electronic spectra and magnetic measurements. The TGA data support the formula and indicate the outer and inner solvents as well as the final residue. The thermodynamic parameters are calculated using the Coats-Redfern and Horowitz-Metzger methods. H2L and [Zn(L)(EtOH)(H2O)] showed the highest cytotoxic activity while H2L has a higher antioxidant activity than ascorbic acid. The ionization constant of the ligand and the stability constant of the Cu(II)sbnd H2L in absence and presence of hexamine buffer were calculated.