Gurunath S. Kurdekar

Synthesis, characterization, antibiogram and DNA binding studies of novel Co(II), Ni(II), Cu(II), and Zn(II) complexes of Schiff base ligands with quinoline core

A series of Co(II), Ni(II), Cu(II), and Zn(II) complexes of Schiff base ligands L1H3 and L2H have been prepared. The ligands are synthesized by the condensation of 2-hydroxy-3-formylquinoline with salicyloylhydrazide and 2-hydrazinobenzothiazole in absolute ethanol. The prepared complexes were characterized by the analytical and spectral techniques. The stoichiometry of the complexes is found to be 1:1. The presence of coordinated and lattice water is confirmed by the TG and DTA studies. Subsequently all the prepared complexes were screened for antimicrobial activity against bacteria and fungi. The Cu(II) complexes have been found to be more active than the ligand. In addition the DNA binding/cleaving capacity of the compounds was analyzed by absorption spectroscopy, viscosity measurement, thermal denaturation, and gel electrophoresis methods.

Synthesis, structure, electrochemistry and spectral characterization of (d-glucopyranose)-4-phenylthiosemicarbazide metal complexes and their antitumor activity against Ehrlich Ascites Carcinoma in Swiss albino mice

The novel glycosyl saccharide derivative, (D-glucopyranose)-4-phenylthiosemicarbazide (LH) and its complexes, with cobalt(II), nickel(II), copper(II) and zinc(II) were synthesized, characterised and tested for cytotoxic effects. The copper complex, [CuLCl] inhibited Ehrlich Ascites Carcinoma (EAC) induced cancer cell lines in Swiss albino mice at LC50=1.94 x 10(-8) (LC50=2.76 x 10(-8) for cisplatin) and so distinctly better than free ligand and other complexes.

Spectroscopy, Electrochemistry, and Structure of 3d-Transition Metal Complexes of Thiosemicarbazones with Quinoline Core: Evaluation of Antimicrobial Property

ABSTRACT A series of Co(II), Ni(II), Cu(II), and Zn(II) complexes of quinoline-thiosemicarbazones was prepared. The Schiff base ligands that provide N, O, and S donor atoms for ligation are synthesized by the condensation of 2-hydroxy-3-formylquinoline with substituted thiosemicarbazides in ethanol. The ligands and complexes are characterized by elemental analysis, infrared, 1H NMR, UV-Vis, fast atom bombardment (FAB) mass spectroscopy, and electron spin resonance (ESR) spectral studies followed by magnetic susceptibility and conductivity measurements. The ligand-to-metal ratio is found to be 1:1 and 2:2 for the complexes of L1H2 and L2H2, respectively. All the complexes are found to have octahedral geometry except [CuL1H(H2O)Cl], which exhibits a square pyramidal structure. All the complexes are nonelectrolytic in nature and the electrochemical behavior of complexes is dealt with briefly. Further ligands and complexes were evaluated for their antimicrobial activity against bacteria Escherichia coli and Pseudomonas aeruginosa and fungi Aspergillus niger and Cladosporidium.

4-Aminoantipyrine-based Schiff-base transition metal complexes as potent anticonvulsant agents

Metal complexes of Co(II), Ni(II), Cu(II), and Zn(II) with ligands (L1H and L2) derived from 4-aminoantipyrine, 2-hydroxy-3-formylquinoline, and isatin were synthesized and characterized by the elemental analysis, conductance measurements, magnetic susceptibility, and spectral analysis. The spectral data revealed that the ligands acted as a neutral tridentate, coordinating to the metal ion through the azomethine nitrogen, phenolic oxygen, and carbonyl oxygen of the 4-aminoantipyrine, 2-hydroxy-3-formylquinoline, and isatin molecule in ligands L1H and L2 only. Both the ligands and their metal complexes were studied for cyclic voltammetry studies. The ligand and the metal complexes were screened for their anticonvulsant activity, and it has been observed that the metal complexes are more potent than the ligands.

Binuclear transition metal complexes of bicompartmental SNO donor ligands: synthesis, characterization, and electrochemistry

A series of new binucleating CoII, NiII, CuII, and ZnII complexes of bicompartmental ligands with SNO donors was prepared. The Schiff bases were obtained by the condensation of 4,6-diacetylresorcinol and mercapto-substituted 1,2,4-triazoles. The ligands and their complexes were characterized by elemental analysis, infrared, 1H-NMR, UV-Vis, FAB-mass, and ESR spectral studies, magnetic susceptibility, and conductivity measurements. All the complexes were monomeric and binuclear. NiII and CoII complexes were octahedral, whereas CuII and ZnII complexes were square planar and tetrahedral, respectively. The compounds are investigated for electrochemical activity.

Versatility in the coordination behavior of a hexatopic compartmental Schiff-base ligand in the architecture of binuclear transition metal(II) complexes

Condensation of 1H-pyrazole-3,5-dicarboxylic hydrazide with 1H-indole-2,3-dione (isatin) yield the compartmental ligand, which is capable of encapsulating two transition metal ions namely CoII, NiII, CuII, and ZnII. The ligand is a binuclear hexadentate chelate with N4O2 donating sites. The pyrazole core provides the diazine fragment, which serves as an endogenous bridge between the two metal centers. In CoII and NiII complexes, the ligand is in the imidol form and the subsequent coordination through the imidol oxygen. In other complexes, the lactonic oxygen takes part in ligation. All the complexes are non-electrolytes and soluble in DMSO, DMF, and acetonitrile. Spectral and magnetic studies along with analytical data suggest octahedral geometry for the CoII and NiII complexes, whereas the CuII and ZnII complexes are assigned square pyramidal geometry. The CuII and NiII complexes show one electron redox behavior and the rest are electrochemically inactive.

Spectroscopy, structure, and electrochemistry of transition metal complexes having [M2N2OS2] coordination sphere

Binuclear transition metal complexes of bicompartmental SNONS donors were synthesized and characterized by various physico-chemical techniques. Two different precursors with chloromethyl/formyl functionality at the 2 and 6 positions of phenolate ring are used to construct the ligands. The quinoxaline scaffolds provide SN donors incorporated at the 2 and 6 positions. Copper and zinc complexes are square pyramidal, whereas nickel and cobalt complexes are octahedral. The influence of two metal centers in terms of cooperative effect on the electronic, magnetic, electrochemical, and structural properties was investigated.

Construction of mononuclear transition metal(II) complexes with bi- and tridentate, neutral hydrazone ligands with a quinoxaline hub

A series of Co(II), Ni(II), Cu(II), and Zn(II) complexes of bi- and tridentate hydrazones were prepared. Ligands L1 and L2 were synthesized by the condensation of 2-mercapto-3-hydrazinoquinoxaline with 2-hydroxy-3-formylquinoline and 3-acetylcoumarin, respectively. The compounds were characterized by various spectro-analytical techniques and magnetic moment studies. The complexes are found to be monomeric and non-electrolytes. In these complexes, [CuL1Cl2] has square pyramidal geometry and others have octahedral. The copper complexes are electrochemically active in the applied potential range.