Study on DNA-Binding and DNA-Cleavage Properties of Cr(III) Complexes with Polypyridyl Ligands

Two new water-soluble Cr(III) complexes [Cr(IP)(2)Cl-2](+) and [Cr(PIP)(2)Cl-2](+) (IP = imidazo[4,5-f][1,10] phenanthroline, PIP = 2-phenylimidazo[4,5-f][1,10] phenanthroline) were synthesized and characterized by elemental analysis, mass spectra, and ultraviolet-visible spectra. The DNA-binding properties of the two complexes were investigated by spectroscopic methods and viscosity measurements. The results indicate that both complexes bind to DNA via an intercalative mode with moderate strength. The fluorescence intensity of both complexes decreases with increasing DNA concentration, similar to those of [Cr(phen)(3)](3+) and [Cr(bpy)(3)](3+). Also, both complexes can cleave pBR-322 DNA in the presence of H2O2, and [Cr(PIP)(2)Cl-2](+) exhibits more effective activity than [Cr(IP)(2)Cl-2](+) under the same condition.