Synthesis, characterization, photocleavage of DNA and cytotoxicity of ruthenium(II) mixed-ligand complexes

Two new ruthenium(II) polypyridyl complexes [Ru(dmb)2(Fpp)](ClO4)2 1 (Fpp = 2-(3′,3′-difluoro-3,4-methylenedioxyphenyl)imidazo[4,5-f][1,10]phenanthroline, dmb = 4,4′-dimethyl-2,2′-bipyridine) and [Ru(bpy)2(Fpp)](ClO4)2 2 (bpy = 2,2′-bipyridine) have been synthesized and characterized by elemental analysis, FAB-MS, ES-MS, IR, 1H NMR and 13C NMR. The DNA-binding behaviors of these complexes were investigated by absorption spectroscopic titration, viscosity measurements, thermal denaturation and photocleavage. The mechanism studies of photocleavage reveal that singlet oxygen (1O2) and superoxide anion radical (O2−) may play an important role in the photocleavage. The cytotoxicity of complexes 1 and 2 have been evaluated by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) method.