Synthesis, structural characterization and DNA studies of trivalent cobalt complexes of (2E)-4N-substituted-2-[4-(propan-2-yl)benzylidene]hydrazinecarbothioamide

Abstract

This paper describes trivalent cobalt complexes of hydrazinecarbothioamides derived from 4-(propan-2-yl) benzaldehyde and substituted thiosemicarbazides NH2NHC(S)NHR, where R = H (1), Me (2), Et (3) or Ph (4) have been synthesized and characterized. The prepared ligands and complexes were characterized using various physicochemical techniques viz. elemental analysis, molar conductance, magnetic susceptibility measurements, IR, electronic absorption spectral studies and cyclic voltammetry. The electronic spectra in DMSO solvent and magnetic susceptibility data of complexes reveal that the complexes are diamagnetic with low spin octahedral cobalt(III) complexes. The absorption titration studies revealed that each of these complexes is an avid binder to calf thymus-DNA. The apparent binding constants are in the order of 107–108 M-1 . The nucleolytic cleavage activities of the ligands and their complexes were assayed on pUC18 plasmid DNA using gel electrophoresis in the presence and absence of H2O2. The ligands showed increased nuclease activity when administered as cobalt complexes. All the complexes behave as efficient chemical nucleases with hydrogen peroxide activation. These studies revealed that the complexes exhibit both oxidative and hydrolytic chemistry in DNA cleavage.