Synthesis, DNA-binding and photocleavage of “light switch” complexes [Ru(bpy)2(pyip)]2+ and [Ru(phen)2(pyip)]2+

Two novel Ru(II) complexes [Ru(bpy)2(pyip)]2+1 and [Ru(phen)2(pyip)]2+2 (bpy = 2,2′-bipyridine; phen = 1,10-phenanthroline; pyip = 2-(pyridine-2-yl)imidazo-[4,5-f][1,10]-phenanthroline), have been synthesized and characterized by elemental analysis, ES-MS, 1H NMR, UV–Vis. The DNA-binding behaviors of both complexes were studied by spectroscopic methods and viscosity measurements. The results indicate that the two complexes can bind to CT-DNA in an intercalative mode, and also show that these two Ru(II) complexes can promote the photocleavage of pBR322 DNA. In addition, In the presence of Co2+, the emission of DNA-[Ru(L)2pyip]2+ can be quenched, which exhibited the DNA “light switch” properties.