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 H-1 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. (C) 2004 Elsevier Inc. All rights reserved.