HETEROLEPTIC MONONUCLEAR RUTHENIUM(II) COMPLEXES: SYNTHESIS, CHARACTERIZATION, DNA CLEAVAGE, ANTIOXIDANT AND CYTOTOXIC ACTIVITIES

Mononuclear ruthenium(II) complexes of the type [Ru(bpy)₂(L)] (PF₆)_2, where L=4,5-bis(4-dimethyaminophenyl)-1H, 1 ‘H-2,2′-biimidazole (1) and 4,5-bis (4-fluorophenyl) – 1H, 1′ H-2,2′-biimidazole (2) have been synthesized and characterized by elemental analyses and  spectroscopic techniques such as UV-visible, IR and ESI-MS. The redox behavior of the complexes has been studied by cyclic and differential pulse voltammetry. Both the complexes show reversible electrochemical wave attributable to Ru(II)/Ru(III) couple. The complexes exhibit half-wave potential (E_1/2) values of +0.8698 V for the complex 1 and +0.8395 V for the complex 2 respectively. Electrophoretic studies showed that the complexes are able to cleave supercoiled plasmid DNA more effectively in the presence of light at the wavelength of 480 nm. The mode of action of DNA cleavage activity was studied using DMSO and histidine. DPPH method has been adopted to find the radical scavenging activity of the newly synthesized ligands and complexes. The cytotoxic activity of these complexes was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay against MCF7 breast cancer cell lines.