Comparative Studies on DNA Binding, Photocleavage, and Photophysical Properties of Ru(II) Complexes Containing TIP {TIP = 2-(Thiophen-2-yl)-1H-imidazo[4,5-f][1,10]-phenanthroline} Ligand

Abstract

A thiophene contained imidazo phenanthroline ligand TIP {TIP = 2-(thiophen-2-yl)-1H-imidazo-[4,5-f][1,10]phenanthroline{ and its mononuclear Ru(II) polypyridyl complexes [Ru(phen)₂TIP]²⁺ (1) (phen = 1,10-phenanthrolene) and [Ru(bpy)₂TIP]²⁺ (2) (bpy = 2,2'-bipyridyl), are synthesized and characterized by UVVis, IR, ¹H and ¹³C NMR, and ESI-MS spectra. Interaction of these complexes with CT-DNA is studied using UV-Vis and florescence spectra, viscosity measurements and molecular docking studies. The latter supports binding ability of complexes with stability constants deduced from UV-Vis and florescence spectra. The studies reveal that both Ru(II) polypyridyl complexes bind to DNA predominantly by intercalation, and the binding constant of complex 1 is greater than that of complex 2. Complexes 1 and 2 cleave the pBR 322 DNA under UV light.