Evaluation of biomolecular interactions and cytotoxic activity of organometallic binuclear Ru(II) complexes of ferrocenyl thiosemicarbazones.

Four new ferrocenyl substituted thiosemicarbazone ligands (-) and their corresponding binuclear ruthenium(II) arene complexes of the general type [(η- cym)(L)Ru(μ-im)Ru(L)(η--cym)]Cl (-) and [(η- cym)(L)Ru(μ-azpy)Ru(L)(η--cym)]Cl (-) (cym = cymene, im = imidazole, azpy = 4,4'-azopyridine) have been synthesized and characterized. The structures of the complexes were established through DFT calculations and geometry optimization. The interactions of the binuclear complexes with DNA were investigated by absorption, emission and viscosity studies which indicated that the complexes bind to DNA intercalation. Meanwhile, the interaction of complexes with the protein, bovine serum albumin (BSA), has also been studied using fluorescence emission spectroscopy. The experimental results show that the binuclear complexes exhibit good binding propensities to BSA. The complexes can quench the intrinsic fluorescence of BSA remarkably through a static or dynamic quenching process. In addition, the cytotoxicity of complexes - against HeLa cell line was assayed which showed lower IC values indicating their higher cytotoxicity and potency in killing the cancer cells at low concentrations.Communicated by Ramaswamy H. Sarma.