A Ru(II) complex with 2-(4-(methylsulfonyl)phenyl)-1H-imidazo[4,5-f][1,10]phenanthroline: synthesis, characterization, and acid-base and DNA-binding properties

A new Ru(II) complex of Ru(bpy)2(Hmspip)]Cl2 {in which bpy=2,2'-bipyridine, Hmspip=2-(4-(methylsulfonyl)phenyl)-1H-imidazo4,5-f]1,10]phenanthroline} have been synthesized and characterized. The ground- and excited-state acid-base properties of Ru(bpy)2(Hmspip)]Cl2 and its parent complex of Ru(bpy)2(Hpip)]Cl2 {Hpip=2-phenyl-1H-imidazo4,5-f]1,10]phenanthroline} have been studied by UV-visible (UV-vis) and emission spectrophotometric pH titrations. Ru(bpy)2(Hmspip)]Cl2 acts as a calf thymus DNA intercalators with a binding constant of 4.0×10(5) M(-1) in buffered 50 mM NaCl, as evidenced by UV-vis and luminescence titrations, steady-state emission quenching by Fe(CN)6]4-, DNA competitive binding with ethidium bromide, reverse salt titrations and viscosity measurements.