Synthesis,characterization, and DNA binding of ruthenium(II) complexes with 2-benzo[b] furan-2-yl-1H-imidazo[4,5f][1,10]phenanthroline as an intercalative ligand

DNA-binding properties of a number of ruthenium complexes with different polypyridine ligands are reported. The new polypyridine ligand BFIP (=2-benzob] furan-2-yl-1H-imidazo4,5-f]1,10]phenanthroline) and its ruthenium complexes Ru(bpy)₂BFIP]²⁺ (bpy = 2,2′-bipyridine), Ru(dmb)₂BFIP]²⁺ (dmb = 4,4′-dimethyl-2,2′-bipyridine), and Ru(phen)₂BFIP]²⁺ (phen = 1,10-phenanthroline) have been synthesized and characterized by elemental analysis, mass spectra, IR, UV-Vis, ¹H- and ¹³C-NMR, and cyclic voltammetry. The DNA binding of these complexes to calf-thymus DNA (CT-DNA) was investigated by spectrophotometric, fluorescence, and viscosity measurements. The results suggest that ruthenium(II) complexes bind to CT-DNA through intercalation. Photocleavage of pBR 322 DNA by these complexes was also studied, and Ru(phen)₂BFIP]²⁺ was found to be a much better photocleavage agent than the other two complexes.