title: Photochemical Properties and Reactivity of a Ru Compound Containing an NAD/NADH-Functionalized 1,10-Phenanthroline Ligand.
abstract: An NAD/NADH-functionalized ligand, benzo[b]pyrido[3,2-f][1,7]-phenanthroline (bpp), was newly synthesized. A Ru compound containing the bpp ligand, [Ru(bpp)(bpy)2](2+), underwent 2e(-) and 2H(+) reduction, generating the NADH form of the compound, [Ru(bppHH)(bpy)2](2+), in response to visible light irradiation in CH3CN/TEA/H2O (8/1/1). The UV-vis and fluorescent spectra of both [Ru(bpp)(bpy)2](2+) and [Ru(bppHH)(bpy)2](2+) resembled the spectra of [Ru(bpy)3](2+). Both complexes exhibited strong emission, with quantum yields of 0.086 and 0.031, respectively; values that are much higher than those obtained from the NAD/NADH-functionalized complexes [Ru(pbn)(bpy)2](2+) and [Ru(pbnHH)(bpy)2](2+) (pbn = (2-(2-pyridyl)benzo[b]-1.5-naphthyridine, pbnHH = hydrogenated form of pbn). The reduction potential of the bpp ligand in [Ru(bpp)(bpy)2](2+) (-1.28 V vs SCE) is much more negative than that of the pbn ligand in [Ru(pbn)(bpy)2](2+) (-0.74 V), although the oxidation potentials of bppHH and pbnHH are essentially equal (0.95 V). These results indicate that the electrochemical oxidation of the dihydropyridine moiety in the NADH-type ligand was independent of the π system, including the Ru polypyridyl framework. [Ru(bppHH)(bpy)2](2+) allowed the photoreduction of oxygen, generating H2O2 in 92% yield based on [Ru(bppHH)(bpy)2](2+). H2O2 production took place via singlet oxygen generated by the energy transfer from excited [Ru(bppHH)(bpy)2](2+) to triplet oxygen.
authors: Institute for Cell-Material Sciences, Kyoto University , ACT-Kyoto #507, Jibucho 105, Fushimi-ku, Kyoto 612-8374, Japan.
authors: Katsuaki
authors: K
authors: Kobayashi
authors: Graduate School of Science and Engineering, University of Toyama , 3190 Gofuku, Toyama 930-8555, Japan.
authors: Hideki
authors: H
authors: Ohtsu
authors: Graduate School of Science and Engineering, University of Toyama , 3190 Gofuku, Toyama 930-8555, Japan.
authors: Koichi
authors: K
authors: Nozaki
authors: Institute for Cell-Material Sciences, Kyoto University , Yoshida, Sakyo-ku, Kyoto 606-8501, Japan.
authors: Susumu
authors: S
authors: Kitagawa
authors: Institute for Cell-Material Sciences, Kyoto University , ACT-Kyoto #507, Jibucho 105, Fushimi-ku, Kyoto 612-8374, Japan.
authors: Koji
authors: K
authors: Tanaka
mesh_terms: D018360:Crystallography, X-Ray; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D009243:NAD / Q000737:chemistry*; D010084:Oxidation-Reduction; D010618:Phenanthrolines / Q000737:chemistry*; D010777:Photochemistry; D017975:Ruthenium Compounds; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet
chemical_list: D008024:Ligands; D010618:Phenanthrolines; D017975:Ruthenium Compounds; D009243:NAD; C025205:1,10-phenanthroline