Synthesis, structure and in vitro biological activity of pyridoxal N(4)-substituted thiosemicarbazone cobalt(III) complexes

摘要

Cobalt(III) complexes containing pyridoxal N(4)-substituted thiosemicarbazone ligands with the composition[Co(HL~(1-2)?Cl)(HL~(1-2)?H_2O)] (1-2) have been synthesized from the reaction of [CoCl_2(PPh_3)_2] and pyridoxal N-methyl-thiosemicarbazone hydrochloride (H_3L~1?Cl)/pyridoxal N-phenyl-thiosemicarbazone hydrochloride (H_3L~2?Cl). The richness of the coordination chemistry of this ligand is highlighted by the modulation of its charge from neutral (H_3L?Cl) (L) to dianionic (HL?Cl) (L~(2-)) and monoanionic forms(HL?H_2O) (L~-) and coordinated as tridentate binegative mode around cobalt(III) ion by forming neutral complex. The new complexes were characterized by various analytical and spectroscopic techniques(IR, electronic, ~1H NMR and ESI-Mass). The X-ray crystal structure of the complex 2, demonstrated distorted octahedral coordination geometry around the metal centre. Further, the investigation of effect of substitution (CH_3 or C_6H_5) on terminal N(4)-nitrogen of thiosemicarbazone exhibited its influence on the potential binding and cleavage ability with DNA, BSA binding, free radical scavenging and cytotoxicity.