Pyrazole bridged binuclear transition metal complexes: Synthesis, characterization, antimicrobial activity and DNA binding/cleavage studies

A new ligand system having pyrazolato endogenous bridging component and N4S2 donating sites is synthesized by the condensation of 3,5-dichloroformyl-1H-pyrazole with phenylthiosemicarbazide. Both ligand and its binuclear Co-II, Ni-II, Cu-II and Zn-II complexes are characterized by the spectral and analytical methods. All the complexes were found to be binuclear monomeric in nature with octahedral geometry and nonelectrolytes. Electrochemical activity is observed only for the Cu-II complex in the applied potential range. Ligand and complexes were screened for antimicrobial activity and made to interact with Escherichia coli DNA to investigate the binding/cleaving ability by absorption, hydrodynamic, thermal denaturation and electrophoresis studies. The copper complex exhibited higher inhibition against a gram negative bacterium, E. coli and shown good intercalating ability with E. coli DNA. (C) 2011 Elsevier B.V. All rights reserved.