title: Photo-induced ring-expansion reactions mediated by B12-TiO2 hybrid catalyst.
abstract: Vitamin B(12)-TiO(2) heterogeneous hybrid catalyst (B(12)-TiO(2)) mediated ring-expansion reactions and their reaction mechanism were clarified by various spectroscopic methods. Diffuse reflectance UV/VIS (DR-UV/VIS) studies showed that B(12)-TiO(2) was activated to form the supernucleophilic Co(I) species of B(12) by irradiation with ultraviolet light. DR-UV/VIS and electron spin resonance (ESR) studies then elucidated the formation of the photo-sensitive intermediate on heterogeneous surfaces. The photo-excited B(12)-TiO(2) catalyzed ring-expansion reactions were efficient and eco-friendly. This catalytic efficiency was strongly dependent on the kind of solvent. The oxidation reaction of the solvent by holes at TiO(2) nanoparticle surfaces had a crucial role in the overall catalytic reaction.
authors.affiliation: Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University, 744, Motooka, Fukuoka, Japan.
authors.forename: Shin-ichiro
authors.initials: S
authors.lastname: Izumi
authors.forename: Hisashi
authors.initials: H
authors.lastname: Shimakoshi
authors.forename: Masaaki
authors.initials: M
authors.lastname: Abe
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Hisaeda