title: Photocatalytic one-electron oxidation of biphenyl derivatives strongly coupled with the TiO2 surface.
abstract: One-electron oxidation of various biphenyl derivatives such as biphenyl (BP), 4-hydroxybiphenyl (HBP), 4,4'-biphenol (DHBP), 4-methoxy-4'-hydroxybiphenyl (MHBP), 4-cyano-4'-hydroxybiphenyl (CNHBP), 4-biphenylmethanol (BPM), and 4-biphenylethanol (BPE) adsorbed on the surface of TiO2 powder slurried in acetonitrile has been investigated by time-resolved diffuse reflectance spectroscopy. From the Langmuir adsorption isotherms for BP and HBP, it is suggested that the OH group plays an important role in adsorbing on the surface ofTiO2. The spectroscopic characteristics of charge transfer complexes of substrates and the TiO2 surface have been studied by steady-state diffuse reflectance spectroscopy. The high efficiency of a one-electron oxidation reaction was observed for hydroxyl-substituted BPs (HBP, DHBP, MHBP, CNHBP), compared with BPM and BPE, indicating that the strength of the electronic coupling element (H(DA)) between the electron acceptor and donor is a key factor in the one-electron oxidation of a substrate adsorbed on the TiO2 powder. The effects of the distance between the electron donor and the acceptor on the electronic coupling element are also discussed.
authors.affiliation: The Institute of Scientific and Industrial Research (SANKEN), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Tachikawa
authors.forename: Sachiko
authors.initials: S
authors.lastname: Tojo
authors.forename: Mamoru
authors.initials: M
authors.lastname: Fujitsuka
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Majima
mesh_terms: D001713:Biphenyl Compounds / Q000737:chemistry*; D002384:Catalysis; D004583:Electrons; D008958:Models, Molecular; D015394:Molecular Structure; D010084:Oxidation-Reduction; D010777:Photochemistry; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*
chemical_list: D001713:Biphenyl Compounds; C009495:titanium dioxide; D014025:Titanium