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

Four new ferrocenyl substituted thiosemicarbazone ligands (L1-L4) and their corresponding binuclear ruthenium(II) arene complexes of the general type [(eta(6)-pcym)(L)Ru(mu-im)Ru(L)(eta(6)-p-cym)]Cl (C1-C4) and [(eta(6)-pcym)(L)Ru(mu-azpy)Ru(L)(eta(6)-p-cym)]Cl-2(C5-C8) (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 DNAviaintercalation. 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, thein vitrocytotoxicity of complexesC1-C8against HeLa cell line was assayed which showed lower IC(50)values indicating their higher cytotoxicity and potency in killing the cancer cells at low concentrations. Communicated by Ramaswamy H. Sarma

Automated summary

New ferrocenyl substituted thiosemicarbazone ligands and their binuclear ruthenium(II) arene complexes have been synthesized and characterized. The structures were established through DFT calculations, and the interactions of the complexes with DNA and BSA have been studied, showing intercalation binding with DNA and good binding affinity with BSA. In vitro cytotoxicity assays against HeLa cell line demonstrated higher potency and cytotoxicity of the complexes at low concentrations.