A comparative study of the interaction of two structurally analogue ruthenium(II) complexes with DNA.

The binding of the ruthenium(II) complexes of [Ru(bpy)2(CAIP)]Cl2 and [Ru(bpy)2(HCIP)]Cl2 (where bpy=2,2'-bipyridine, CAIP=4-carboxyl-imidado[4,5-f][1,10]-phenanthroline, HCIP=3-hydroxyl-4-carboxyl-imidado[4,5-f][1,10]-phenanthroline) to calf thymus DNA (ct-DNA) has been investigated with UV-visible and emission spectroscopy, steady-state emission quenching, and viscosity measurements. The experimental results indicate that the two complexes bind to ct-DNA through an intercalative mode and [Ru(bpy)2(HCIP)]2+ intercalates into DNA more deeply than [Ru(bpy)2(CAIP)]2+ does.