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Sample records for ligands synthesis spectral

  1. 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

  2. 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.

  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 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

  7. 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

  8. 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.

  9. 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

  10. 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.

  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

    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.

  13. 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

  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

    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.

  19. 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

  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. 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

  1. 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.

  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. 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.

  4. 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

  5. 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.

  6. 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

  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. 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

  12. 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

  13. 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

  14. 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.

  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. 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

  20. 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…

  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. 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

  3. 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

  4. 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

  5. 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.

  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. 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

  5. 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

  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. 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

  13. 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.

  14. 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

  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 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.

  6. 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.

  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. 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.

  15. 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

  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. 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

  2. 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.

  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. 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

  10. 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

  11. 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

  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. 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.

  14. 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.

  15. 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

  16. 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

  17. 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.

  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 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

  12. 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

  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. 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).

  18. 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

  19. 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.

  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. 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

  3. 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

  4. 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

  5. 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.

  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 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.

  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.