Synthesis, characterization, DNA-binding and DNA-photocleavage studies of [Ru(bpy)2(BPIP)]2+ and [Ru(phen)2(BPIP)]2+ (BPIP = 2-(4′-biphenyl)imidazo[4,5-f][1,10]phenanthroline)

New ligand 2-(4′-biphenyl)imidazo[4,5-f][1,10]phenanthroline (BPIP) and its complexes [Ru(bpy)2(BPIP)]2+ (1) (bpy = 2,2′-bipyridine) and [Ru(phen)2(BPIP)]2+ (2) (phen = 1,10-phenanthroline) have been synthesized and characterized by mass spectroscopy, 1H NMR and cyclic voltammetry. The interaction of two Ru(II) complexes with calf thymus DNA (CT-DNA) was investigated by spectroscopic and viscosity measurements. Results indicate that both complexes bind to DNA via an intercalative mode and the DNA-binding affinity of complex 2 is much greater than that of complex 1. Furthermore, when irradiated at 365 nm, both complexes have also been found to promote the photocleavage of plasmid pBR 322 DNA.

Graphical abstractPhotoactivated cleavage of pBR 322 DNA in the presence of Ru(II) complexes, light after 60 min irradiation at 365 nm. Lane 0 and Lane 5, DNA alone; Lanes 1–4, in the different concentrations of complex 1: (1) 20; (2) 40; (3) 60; (4) 80 μM; Lanes 6–9, in the different concentrations of complex 2: (6) 20; (7) 40; (8) 60; (9) 80 μM.Figure optionsDownload full-size imageDownload as PowerPoint slide