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Abstract: A three-dimensional supramolecule of [Cu(3,2,3-tet)] n {[Ag2(CN)4]} n (1), (3,2,3-tet = N,N′-bis(3-aminopropyl)ethylenediamine), in which [Cu(3,2,3-tet)]2+ cations are suspended in the two-dimensional anionic networks composed of [Ag2(CN)4]2+ building blocks, was synthesized and characterized by X-ray crystallography. Every silver(I) ion is five-coordinated including the silver–silver interaction in anionic network. Variable temperature magnetic susceptibility data indicate weak antiferromagnetic interaction (−0.378cm−1) between copper(II) ions in 1. [Copyright &y& Elsevier]

Abstract: Reaction of tridentate ONS donor ligands H2L1, H2L2 and H2L3 (H2L1 =2-hydroxyacetophenone hexamethyleneimine-3-thiosemicarbazone; H2L2 =2-hydroxyacetophenone morpholine-3-thiosemicarbazone; H2L3 =2-hydroxyacetophenone N(4)-methyl, phenyl thiosemicarbazone) with Mn(OAc)2 ·4H2O afforded manganese(IV) complexes of the type [MnL2] in an ethanol–methanol mixture under air. The crystal structure of Mn(L2)2 ·0.25H2O reveals an octahedral geometry with the ligand coordinated in a meridional fashion. The molecule is packed in the crystal lattice with extended hydrogen bonding networks. EPR spectra of the complexes in frozen solution at 77K show a weak signal at g ≈4 and a strong sextet at g ≈2 consistent with manganese(IV) in an octahedral environment. Cyclic voltammetry in DMSO/ dichloromethane show quasi-reversible peaks corresponding to the Mn(IV)/Mn(III) redox couple. [Copyright &y& Elsevier]

An interesting series of eight neutral ternary Co(III) complexes of 2-hydroxyacetophenone N(4)-substituted thiosemicarbazones (H2L), bidentate heterocyclic bases 2,2′-bipyridine (bipy)/1,10-phenanthroline (phen) and azide with a general formula [MLB(N3)] were prepared. The complexes were characterized by means of spectroscopic methods. The coordination geometry around Co(III) in all the complexes is distorted octahedral with one dibasic tridentate ligand L2−, one bidentate heterocyclic base and one terminally coordinated azide group. Crystal structure of the compound CoL4bipyN3 was completely solved. All the electronic transitions were assigned. All complexes were diamagnetic indicating cobalt in a d6 strong field. [Copyright &y& Elsevier]

A Pd 2 L 4 type supramolecular coordination driven self assembly was constructed using a dipodal pyridyl terminal ligand L [ L = N 2 , N 6 -dimethyl- N 2 , N 6 -bis((pyridin-4-yl)methyl)naphthalene-2,6-dicarboxamide] and palladium nitrate. The self-assembly was fully characterized by 1D and 2D NMR, ESI-MS, IR, TGA, HR-TEM and elemental analysis. The geometry optimization was performed using the Hartree–Fock method. The assembly acts as an efficient, reusable, heterogeneous catalyst for Buchwald–Hartwig amination reaction in toluene under phosphine free condition and aerobic medium. [ABSTRACT FROM AUTHOR]

An interesting series of four complexes of acenaphthoquinone 3-(4-benzylpiperidyl) thiosemicarbazones (HL), with a general formula [Co II L 2 ]( 1 ), [Ni II L 2 ]( 2 ), [Cu II L 2 ]( 3 ), and [Zn II L 2 ]( 4 ), were prepared. The complexes were characterized by means of elemental analysis, IR, UV–Vis spectroscopy and ESI-MS methods. In all the complexes the ligand (HL) coordinate as a monobasic ligand in tridentate fashion. The crystal structure of the compounds 1 and 2 were determined by single crystal X-ray diffraction experiment. The geometry and bonding parameters of the compound 3 were determined from EPR spectra. The g values of 3 , calculated from EPR at 77 K, indicate a rhombic coordination geometry about copper(II). The room temperature magnetic moment of the cobalt(II) complex 1 , indicate that it is in high spin state, while the nickel(II) complex, 2 , is paramagnetic. The redox behavior of the ligand and its complexes were studied by cyclic voltammetry. The density functional theory (DFT) was used for geometry optimization, determination of HOMO and LUMO energies, HOMO–LUMO energy gap and dipole moment of the compounds. Antibacterial activity of the ligand and complexes 1 – 4 , have been screened against two gram negative bacteria Escherichia coli , Pseudomonas aeruginosa and two gram positive bacteria Staphylococcus aureus and Bacillus subtilis. The electron micrograph images display damage to microbial cell wall upon treatment with the compounds. [ABSTRACT FROM AUTHOR]

Three novel trinuclear Ni(II) complexes, [Ni 3 (L 1 ) 2 (py) 4 ] ( 1 ), [Ni 3 (L 2 ) 2 (H 2 O) 2 (DMA) 2 ] ( 2 ) and [Ni 3 (L 3 ) 2 (py) 4 ] ( 3 ), with trianionic pentadentate ligands derived from salicylhydrazide with N-acyl substituents [H 3 L 1 = N 2 -crotonoylsalicylhydrazide, H 3 L 2 = N 2 -(3,3-dimethylacryloyl)salicylhydrazide, H 3 L 3 = N 2 -cinnamoylsalicylhydrazide] were synthesized and characterized by elemental analysis, spectroscopic techniques, like UV–Vis, FT-IR and NMR, molar conductivity and magnetic susceptibility measurements, and single crystal X-ray diffraction. The solid state structures of the complexes reveal the binding modes of the different ligands via ONO donor atoms. Complex 1 crystallises in the triclinic system while complexes 2 and 3 crystallise in the monoclinic system with space groups P 1 ¯ ( 1 ) and P 2 1 / c ( 2 and 3 ). Computational studies were performed using Density Functional Theory (DFT) to obtain physical properties of all three complexes. The ligands and their metal complexes were screened for antibacterial activity to assess their inhibition potential against two Gram positive bacteria; Staphylococcus aureus and Bacillus subtilis and two Gram negative bacteria; Escherichia coli and Pseudomonas aeruginosa by the well diffusion method using gentamicin as a positive control. Antibacterial screening data reveals that the trinuclear Ni(II) complexes have significantly enhanced inhibitory activities compared to the ligands. [ABSTRACT FROM AUTHOR]

A novel chemo-sensor based on diaminobenzidine (H 2 L) was synthesized and characterized. The chemo-sensor shows selective “turn-on” fluorescence response to Zn 2+ ion over a variety of other competing metal ions such as Al 3+ , Mn 2+ , Fe 3+ , Co 2+ , Ni 2+ , Cu 2+ , and Cd 2+ . The strong fluorescent emission can be observed even at ppm level concentration of the probe in the presence of Zn 2+ with over 54 fold intensity enhancement at 509 nm. Similar fluorescence behaviour is also observed in a variety of solvents and solvent mixtures in the presence of zinc(II). The fluorescent emission is also detected when the H 2 L sample solution containing Zn 2+ is exposed to UV radiation. The sensitive nature of fluorescent response of the probe to Zn 2+ is gauged from the very low detection limit of 8.6 × 10 −9 M. The chemo-sensor H 2 L binds to zinc(II) in 1:1 stoichiometry as determined by Job's plot and the binding constant is calculated as 7.8 × 10 4 M −1 . [ABSTRACT FROM AUTHOR]

Abstract: Six new copper(II) complexes of 2-hydroxyacetophenone-N(4)-phenyl semicarbazone have been synthesized and physico-chemically characterized. The tridentate character of the semicarbazone is inferred from IR spectra. Based on EPR studies, the spin Hamiltonian and bonding parameters have been calculated. The g values, calculated for all the complexes in frozen DMF, indicate the presence of the unpaired electron in the orbital. The metal–ligand bonding parameters evaluated showed strong in-plane σ and in-plane π-bonding. The structure of the compound, CuLphen has been resolved using single crystal X-ray diffraction studies. The crystal structure revealed a monoclinic lattice with space group symmetry P21/c. The compound adopts a distorted square pyramidal geometry with a N2O2 core as the base. [Copyright &y& Elsevier]