Interaction of polypyridyl ruthenium (II) complex containing asymmetric ligand with DNA

A novel asymmetric bidentate ruthenium (II) complex, [Ru(bpy)2(PYNI)]2+ (bpy = 2,2′-bipyridine, PYNI = 2-(2′-pyridyl)naphthoimidazole), has been synthesized and characterized by elemental analysis, ES-MS (electrospray mass spectra) and 1H NMR. The electrochemical behaviors of this complex were studied by cyclic voltammetry. DNA interaction studies suggest that [Ru(bpy)2(PYNI)]2+ binds to calf thymus DNA (CT-DNA) in an intercalative mode. Interestingly, this new Ru(II) complex has also been found to promote cleavage of plasmid pBR 322 DNA from the supercoiled form I to the open circular form II upon irradiation.