title: Formation of a long-lived electron-transfer state in mesoporous silica-alumina composites enhances photocatalytic oxygenation reactivity.
abstract: A simple donor-acceptor linked dyad, 9-mesityl-10-methylacridinium ion (Acr(+)-Mes) was incorporated into nanosized mesoporous silica-alumina to form a composite, which in acetonitrile is highly dispersed. In this medium, upon visible light irradiation, the formation of an extremely long-lived electron-transfer state (Acr(•)-Mes(•+)) was confirmed by EPR and laser flash photolysis spectroscopic methods. The composite of Acr(+)-Mes-incorporated mesoporous silica-alumina with an added copper complex [(tmpa)Cu(II)] (ClO(4)(-))2 (tmpa = tris(2-pyridylmethyl)amine) acts as an efficient and robust photocatalyst for the selective oxygenation of p-xylene by molecular oxygen to produce p-tolualdehyde and hydrogen peroxide. Thus, incorporation of Acr(+)-Mes into nanosized mesoporous silica-alumina combined with an O(2)-reduction catalyst ([(tmpa)Cu(II)](2+)) provides a promising method in the development of efficient and robust organic photocatalysts for substrate oxygenation by dioxygen, the ultimate environmentally benign oxidant.
authors.affiliation: Department of Material and Life Science, Division of Advanced Science and Biotechnology, Graduate School of Engineering, Osaka University, Suita, Osaka, Japan. fukuzumi@chem.eng.osaka-u.ac.jp
authors.forename: Shunichi
authors.initials: S
authors.lastname: Fukuzumi
authors.forename: Kaoru
authors.initials: K
authors.lastname: Doi
authors.forename: Akinori
authors.initials: A
authors.lastname: Itoh
authors.forename: Tomoyoshi
authors.initials: T
authors.lastname: Suenobu
authors.forename: Kei
authors.initials: K
authors.lastname: Ohkubo
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Yamada
authors.forename: Kenneth D
authors.initials: KD
authors.lastname: Karlin
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry*; D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D006861:Hydrogen Peroxide / Q000737:chemistry*; D010084:Oxidation-Reduction; D055668:Photochemical Processes; D016062:Porosity; D012822:Silicon Dioxide / Q000737:chemistry*; D014992:Xylenes / Q000737:chemistry*
chemical_list: D014992:Xylenes; D012822:Silicon Dioxide; D003300:Copper; D006861:Hydrogen Peroxide; D000537:Aluminum Oxide