Search

The reaction of Schiff base 2-(4-(dimethylamino)benzylideneamino)phenol (DBAP) and diethylenetriamine/ethylenediamine with cobalt(II) and copper(II) metal ion in equimolar ratio afforded mixed ligand complexes [M(DBAP)(L)Cl(H2O)n] (1–4), where M = Co(II) 1, 2; Cu(II) 3, 4; L = diethylenetriamine (1, 3); n = 0 and ethylenediamine (2, 4); n = 1. All the newly synthesized complexes were characterized by elemental analysis, spectroscopic techniques viz., UV-vis, FT-IR, ESR, PXRD and mass spectrometry. The influence of chelation of cobalt(II) and copper(II) ion on nonlinear optical properties of Schiff base (DBAP) were examined with DFT study. The polarizability (α0) and first-order hyperpolarizability (β) of ligand and their metal complexes were calculated and compared with reference molecule p-nitroaniline. The hyperpolarizability of Schiff base and their metal complexes show a good nonlinear optical behavior. Theoretical investigation of the complexes was performed by DFT using B3LYP level of theory on the basis set 6-31 G (d, p)/LanL2DZ. On the basis of spectroscopic data and DFT computation, a six-coordinate geometry is tentatively proposed around the metal ion. In vitro antibacterial activities of these complexes were also screened against V. cholerae and E. coli, and found to have good antibacterial activity. [ABSTRACT FROM AUTHOR]

The Schiff base derived from curcumin and lysine and its Co, Ni, Cu and Zn(II) complexes have been synthesized and characterized by FT-IR, UV-Vis, 1H NMR and elemental analysis. Conductivity measurement showed a non-electrolytic complex. Thermogravimetric (TG/DTG) analyses of Cu complex confirm the stability followed by thermal decomposition in different steps. The UV-Vis and magnetic susceptibility data of the complexes suggest tetrahedral geometry around the central metal ion except the Cu(II) complex which has a square planar geometry. The XRD and SEM studies revealed the nanocrystalline behavior for the complex. The antimicrobial activity of the Schiff base and its metal chelates were screened against bacteria, such as E. coli and P. aeruginosa. The antifungal activity was screened against C. albicans. The result shows that metal chelates have better antimicrobial activity than the Schiff base. The larvicidal activity of the Schiff base and its metal complexes have been studied and the result revealed that the Cu(II) complex shows more activity than the Schiff base. [ABSTRACT FROM AUTHOR]

The chitosan–(Fe(II), Co(II), and Cu(II)) complexes were prepared by mixing chitosan (Chi) powder with a salicylaldehyde (Sal, 5-hydrogen (–H)) and their 5-bromo (–Br), 5-chloro (–Cl), 5-methoxy (–OCH3), 5-fluoro (–F), 5-methyl (–CH3), and 5-nitro (–NO2) derivatives (groups R) and mixing these with FeCl2and CuCl2in ethanol and with Co(CH3COO)2solutions in butanol at 80 °C over 8 h in heterogeneous phase, followed by extraction with ethanol and butanol, respectively. The complexes were characterized by FTIR and UV–vis spectroscopy, elemental analysis, and cyclic voltammetry. A linear correlation between the metal formal potentialversusthe Hammett parameters of the substituents was observed. The electron-withdrawing groups shift the redox potential to positive values, as a result of lowering the energy of the highest occupied molecular orbital. The formal potential was used as a measurement for the driving force of chitosan complexes for redox reactions. [ABSTRACT FROM PUBLISHER]

Seven new Schiff base complexes of oxovanadium(IV), [VO(L)(H2O)], whereH2L = H2bmpph-gls, H2bumpph-gls, H2iso-vmpph-gls, H2pmpph-gls, H2iso-bumpph-gls, H2ampph-gls, and H2vmpph-gls, have been synthesized by the reaction ofVOSO4·5H2Oand the said ligands in aqueous ethanol. The resulting complexes have been characterized on the basis of elemental analysis, vanadium determination, molar conductance, magnetic measurements, thermogravimetric (TG) analysis, infrared, electronic mass, and electron spin resonance studies. The thermal decomposition processes of one representative complex is discussed, and the order of reaction (n) and the activation energies (Ea) have been calculated from TG and differential TG curves. Molecular geometry optimizations, molecular surface electrostatic potentials, vibrational frequency calculations, bond lengths, bond angles and dihedral angles, and natural atomic charges obtained by natural bond orbital and Mulliken population analysis and calculations of molecular energies, highest occupied molecular orbital and lowest unoccupied molecular orbital were performed with the Gaussian 09 software package using density functional theory methods with Becke3–Lee–Yang–Parr (B3LYP) hybrid exchange–correlation functional and the standard 6-311G(+) basis set for (ampph-glsH2) and LANL2DZ basis set for one of its complexes, [VO(ampph-gls)(H2O)]. No imaginary frequency was found in the optimized model compounds, and hence it ensures that the molecule is in the lowest point of the potential energy surface, that is, an energy minimum. Finally calculated results were applied to simulate infrared spectra which show good agreement with observed spectra. Based on experimental and theoretical data, suitable square pyramidal structures have been proposed for these complexes. Seven new Schiff base complexes of oxovanadium(IV) of the general composition [VO(L)(H2O)], whereH2L = H2bmpph-gls, H2bumpph-gls, H2iso-vmpph-gls, H2pmpph-gls, H2iso-bumpph-gls, H2ampph-gls, and H2vmpph-gls has been synthesized by the reaction ofVOSO4·5H2Oand the said ligands in aqueous ethanol medium. Optimized structure of Complex [VO(ampph-gls)(H2O)] [ABSTRACT FROM AUTHOR]

Ni(II), Cu(II), and Co(II) complexes, ML2, with a new thioether containing ONS donors were synthesized, where L = deprotonated Schiff base. The analytical, spectral (FTIR,1H NMR, and UV-vis), conductivity, and magnetic studies show that the metal complexes possess octahedral geometry and are non-electrolytes. The coordination mode of ligand,1, and nickel(II) complex, NiL2,2, was determined by single-crystal X-ray diffraction studies. Here, the nickel is coordinated to two oxygens, two nitrogens, and two sulfurs of two tridentate ligands with slightly distorted octahedral environment around nickel. The copper complex shows very good catalytic activities towards oxidation of organic thioethers to the corresponding sulfoxide predominantly using H2O2as the oxidant. A series of Ni(II), Cu(II), and Co(II) complexes, ML2, of a new thioether containing ONS donors have been synthesized, where L = deprotonated Schiff base. The analytical, spectral (FTIR,1H NMR, UV–vis), conductivity, and magnetic studies showed that the metal complexes possess octahedral geometry and are non-electrolytes. The structures of ligand as well as nickel(II) complex, NiL2,2, were determined by single-crystal X-ray diffraction studies. The copper complex shows very good catalytic activities towards oxidation of organic thioethers to the corresponding sulfoxide predominantly using H2O2as the oxidant. [ABSTRACT FROM PUBLISHER]

Ruthenium(II) complexes with 2-acetylpyridine-thiosemicarbazones (L1–L4) were synthesized and characterized by analytical and spectral (FT-IR, UV–vis, NMR [1H,13C and31P], and ESI-Mass) methods. Systematic biological investigations, free radical scavenging, anticancer activities, and DNA cleavage studies, were carried out for the complexes. Antioxidant studies showed that the complexes have significant antioxidant activity against DPPH, hydroxyl, nitric oxide radicals and hydrogen peroxide assay. Thein vitrocytotoxicity of complexes against breast cancer (MCF-7) cell line was assayed showing high cytotoxicity with low IC50values indicating their efficiency in destroying the cancer cells even at very low concentrations. The DNA cleavage studies showed that the complexes efficiently cleaved DNA. [ABSTRACT FROM PUBLISHER]

By condensation of amantadine and 4-methoxysalicylaldehyde a new Schiff baseHLwas synthesized. A mixture ofHLand zinc(II) chloride in an alcoholic medium leads to [Zn(HL)2Cl2] (1). However, the same reactants gave another different complex (ZnL2) (2) in the presence of NaOH. The two complexes were characterized by IR,1H NMR, elemental analysis, molar conductance, and single-crystal X-ray diffraction. X-ray diffraction analysis reveals that complex1crystallizes in the triclinic system,P? space group; each asymmetric unit consists of one zinc(II), twoHL, and two chlorides. The tetra coordination of central zinc is attained by two chlorides and two oxygens from the Schiff base, forming a distorted tetrahedral geometry. Complex2crystallizes in the monoclinic system,P21/cspace group; each asymmetric unit consists of one zinc(II) and twoL. The tetra coordination of central zinc is attained by two nitrogens and two oxygens from the Schiff base, forming a distorted tetrahedral geometry. [ABSTRACT FROM PUBLISHER]

A Zn(II) complex with an organoselenium substituted Schiff base, bis{2-[(benzylimino)methyl]-4,6-dihydroselenophenol}Zn(II), has been synthesized and characterized by elemental analyses and X-ray diffraction. Zn(II) is four-coordinated by two phenolate O and two imine N from two organoselenium substituted Schiff-base ligands, forming a distorted tetrahedral geometry. The title complex and its ligand were testedin vitrofor their antibacterial and antitumor activity with the complex showing higher antibacterial and antitumor activities. [ABSTRACT FROM AUTHOR]

Treatment ofN,N′-bis(salicylidene)-1,2-cyclohexanediamine (H2L) with PdCl2in the presence of triethylamine afforded [Pd(N2O2)]. Recrystallization in chloroform and acetonitrile (1 : 1) gave suitable crystals for X-ray crystallography. The solid-state structure shows that the environment around palladium is square planar. The structural parameters of the molecule obtained by density functional theory (DFT) calculation in the gas phase and by X-ray diffraction are compared. The Pd(II) Schiff base complex adopts planar geometry by DFT calculation. The coordination site structural parameters, which are obtained from geometry optimization calculation, are close to those from X-ray crystallographic data. The spectral properties such as vibrational frequencies, chemical shifts, electronic excitation and the natural bond orbital analyses of Pd(Salen) are calculated, analyzed and compared with experimental data. [ABSTRACT FROM AUTHOR]

A new dinuclear zinc(II) complex, [Zn2(L¹)2(N3)2] (1), and a new polynuclear cadmium(II) complex, [Cd2(L²)2(N03)(μ2-dca)]n (2), where L¹ and L are deprotonated forms of 2-[(2-ethylami-noethylimino)methyl]-6-methylphenol and 2-[(2-ethylaminoethylimino)methyl]-4-methoxyphenol, respectively, have been prepared and characterized by elemental analysis, IR spectra, and single crystal X-ray diffraction. The thermal stability and fluorescence of the complexes were also investigated. [ABSTRACT FROM AUTHOR]

A mesogenic Schiff-base, N,N′-di-(4-decyloxysalicylidene)-1′,3′-diaminobenzene, H2ddsdbz (abbreviated as H2L), that exhibits a nematic mesophase was synthesized and its structure was studied by elemental analysis, mass spectrometry, NMR, and IR spectral techniques. The Schiff-base, H2L, upon condensation with hydrated lanthanide(III) nitrates yields LnIII complexes, [Ln2(LH2)3(NO3)4](NO3)2, where Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, and Ho. Analyses of the IR and NMR spectral data imply bidentate Schiff-base through two phenolate oxygen atoms in its zwitterionic form to LnIII, rendering the overall geometry of the complexes as a seven-coordinate polyhedron – possibly distorted mono-capped octahedron. Polarizing optical microscope and differential scanning calorimetry studies reveal that despite H2L being mesogenic, none of the LnIII complexes synthesized under this study exhibits mesomorphism. [ABSTRACT FROM PUBLISHER]

The complex [MnIV(napbh)2] (napbhH2 = N-(2-hydroxynaphthalen-1-yl)methylenebenzoylhydrazide) reacts with activated ruthenium(III) chloride in methanol in 1 : 1.2 molar ratio under reflux, giving heterobimetallic complexes, [MnIV(napbh)2RuIIICl3(H2O)] · [RuIII(napbhH)Cl2(H2O)] reacts with Mn(OAc)2·4H2O in methanol in 1 : 1.2 molar ratio under reflux to give [RuIII(napbhH)Cl2(H2O)MnII(OAc)2]. Replacement of aquo in these heterobimetallic complexes has been observed when the reactions are carried out in the presence of pyridine (py), 3-picoline (3-pic), or 4-picoline (4-pic). The molar conductances for these complexes in DMF indicates 1 : 1 electrolytes. Magnetic moment values suggest that these heterobimetallic complexes contain MnIV and RuIII or RuIII and MnII in the same structural unit. Electronic spectral studies suggest six coordinate metal ions. IR spectra reveal that the napbhH2 ligand coordinates in its enol form to MnIV and bridges to RuIII and in the keto form to RuIII and bridging to MnII. [ABSTRACT FROM AUTHOR]

A series of metal complexes of Schiff bases derived from condensation of sulfa-guanidine with 1-benzoylacetone (H2L1), 2-hydroxybenzophenol (H2L2), dibenzoylmethane (H2L3), 5-methylisatine (H2L4), and 1-methylisatine (H2L5) have been synthesized. The complexes are characterized by elemental analysis, molar conductance, magnetic moment measurements, IR, UV-Vis, 1H NMR, and ESR spectra, as well as thermogravimetric analysis. The low molar conductance values indicate the complexes are nonelectrolytes. IR and 1H NMR spectra show that H2L1-H2L5 are coordinated to metal ions by two bidentate centers. Mn(II), Co(II), Ni(II), and Cu(II) complexes display paramagnetic behavior, whereas the Zn(II)-complex was diamagnetic. All studies confirm the formation of an octahedral geometry for [Cu2L1(AcO)2(H2O)6] · 3H2O (1), [Mn2L4(AcO)2(H2O)6] · 2H2O (6), [Ni2L4(AcO)2(H2O)6] · 2H2O (8), a tetrahedral geometry for [Cu2L2(AcO)2(H2O)2] (2), [Cu2(L4)2] (4), [Co2(L4)2] · 2H2O (7) and [ZnHL4(AcO)(H2O)] · 2H2O (9) and a trigonal bipyramid geometry for [Cu2L3(AcO)2(H2O)4] (3) and [Cu2HL5(AcO)3(H2O)3] · H2O (5). H2L4 was most effective on Gram negative, Gram positive bacteria, and fungi (diameters inhibition zone ranged between 10.5-27.5 mm) after 24 and 48 h, respectively. Complex 8 showed moderate antimicrobial activity. Its minimum inhibitory concentration (MIC) against Escherichia coli, Bacillus subtilis, Candida albicans and Aspargllus flavas was 20 mg L-1. The compound proved to be of moderate toxicity and its LD50 was 20 mg L-1. [ABSTRACT FROM AUTHOR]

Schiff-base complexes [ML(H2O)2(Ac)]nH2O (M = Co(II), Ni(II) and Zn(II); L = Schiff-base ligand derived from 2-acetylpyridine and alanine and n = 1-3/2) were synthesized and characterized by elemental analysis, spectral (FTIR, UV/Vis, MS, 1H-NMR), thermal (TGA), conductance and magnetic moment measurements. The results suggest octahedral geometry for all the isolated complexes. IR spectra show that the ligand coordinates to the metal ions as mononegative tridentate through pyridyl nitrogen, azomethine nitrogen and carboxylate oxygen after deprotonation of the hydroxyl group. Semi-empirical calculations PM3 and AM1 have been used to study the molecular geometry and the harmonic vibrational spectra to assist the experimental assignments of the complexes. [ABSTRACT FROM AUTHOR]

Eight novel cyclic and acyclic Schiff-base ligands, L 1 = 6-amino-3-methyl-1-phenyl-4-aza-3-hepten-1-one, L 2 = 3,7-diaza-2,4,8-trimethyl-6-phenylnona-3,7-diene-1,9-diamine, L 3 = 4,7-diaza-3,5,8-trimethyl-1,10-diphenyldeca-3,7-diene-1,10-dione, L 4 = 3,5,10,14-tetramethyl-7,12-diphenyl-1,4,8,11-tetraazacyclotetradeca-4,7,11,14-tetraene, L 5 = 7-amino-3-methyl-1-phenyl-4-aza-3-hepten-1-one, L 6 = 4,8-diaza-5-methyl-7-phenylundeca-4,8-diene-1,11-diamine, L 7 = 4,8-diaza-3,9-dimethyl-1,11-diphenyldideca-1,11-dione and L 8 = 2,12-dimethyl-4,10-diphenyl-1,5,9,13-tetraazacyclohexadeca-1,4,9,12-tetraene, have been prepared and characterized by elemental analysis, IR, 1 H NMR and mass spectroscopy. Their corresponding Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes ( 1 - 15 ) have been prepared by the reaction of the ligand with the metal sulfate or chloride in a 1:1 molar ratio and characterized by elemental analysis, thermogravimetric analysis (TGA), IR, electronic and magnetic susceptibility measurements. Electronic spectra and magnetic susceptibility measurements of the solid complexes indicate an octahedral geometry around Cu(II), Co(II), Ni(II), Zn(II) and Cd(II) and a square-planar geometry around the Ni(II) complexes of L 2 and L 3 . The ion is coordinated to the central metal(II) ion as a bidentate ligand through two oxygen atoms in all of the complexes except those with Ni(II). The chloride ion is coordinated to the central Ni(II) ion in complexes of L 1 . The conductances of the complexes are very low, indicating their nonelectrolytic nature except for the Ni complex of L 2 , whose molar conductance of 192.5 ohm -1 mol -1 cm 2 indicates an ionic character for [NiL 2 ]Cl 2 . The antifungal properties of the ligands and their complexes were investigated. [ABSTRACT FROM AUTHOR]