Pyrazole-bridged late first row transition metal complexes derived from hexadentate compartmental ligand: synthesis, characterization, antibacterial activity, and DNA binding/cleavage studies

Abstract

A series of binuclear CoII, NiII, CuII, and ZnII complexes having μ-1,2 diazine bridging have been prepared and characterized by various physicochemical methods. The hexadentate ligand is synthesized by condensing pyrazole-3,5-dicarbohydrazide with 2-hydroxynaphthaldehyde (LH3) in 1:2 ratio. All the complexes were found to be monomeric in nature with octahedral geometry and act as nonelectrolytes. Ligand and complexes were screened for antibacterial activity against Escherichia coli and made to interact with its DNA to investigate the binding/cleaving ability by absorption, hydrodynamic, thermal denaturation, and electrophoresis studies. An intercalative binding mode is predicted by the results. Gel electrophoresis data indicate cleavage of DNA to a greater extent by both ligand and complexes.