Abstract
DNA-binding properties of a number of ruthenium complexes with different polypyridine ligands are reported. The new polypyridine ligand BFIP (=2-benzo[b] furan-2-yl-1H-imidazo[4,5-f][1,10]phenanthroline) and its ruthenium complexes [Ru(bpy)2BFIP]2+ (bpy = 2,2′-bipyridine), [Ru(dmb)2BFIP]2+ (dmb = 4,4′-dimethyl-2,2′-bipyridine), and [Ru(phen)2BFIP]2+ (phen = 1,10-phenanthroline) have been synthesized and characterized by elemental analysis, mass spectra, IR, UV-Vis, 1H- and 13C-NMR, and cyclic voltammetry. The DNA binding of these complexes to calf-thymus DNA (CT-DNA) was investigated by spectrophotometric, fluorescence, and viscosity measurements. The results suggest that ruthenium(II) complexes bind to CT-DNA through intercalation. Photocleavage of pBR 322 DNA by these complexes was also studied, and [Ru(phen)2BFIP]2+ was found to be a much better photocleavage agent than the other two complexes.