Synthesis, DNA-binding and photocleavage studies of the ruthenium(II) complexes [Ru(phen)(2)(ppd)](2+) and [Ru(phen)(ppd)(2)](2+) (ppd = pteridino[6,7-f] [1,10]phenanthroline-11,13(10H,12H)-dione, phen=1,10-phenanthroline)

摘要

Two new complexes, [Ru(phen)(2)(ppd)](2+) (1) and [Ru(phen)(ppd)(2)](2+) (2) (ppd = pteridino[6,7-f] [1,10]phenanthroline-11, 13(10H,12H)-dione, phen=1,10-phenanthroline) were synthesized and characterized by ES-MS, H-1-NMR spectroscopy, and elemental analysis. The intercalative DNA-binding properties of 1 and 2 were investigated by absorption-spectroscopy titration, luminescence-spectroscopy studies, thermal denaturation, and viscosity measurements. The theoretical aspects were further discussed by comparative studies of 1 and 2 by means of DFT calculations and molecular-orbital theory. Photoactivated cleavage of pBR322 DNA by the two complexes were also studied, and 2 was found to be a much better photocleavage reagent than 1. The mechanism studies revealed that singlet oxygen and the excited-states redox potentials of the complex may play an important role in the DNA photocleavage.