title: Pyrene-sensitized electron transport across vesicle bilayers: Dependence of transport efficiency on pyrene substituents.
abstract: Endoergic electron transport across vesicle bilayers from ascorbate (Asc-) in the inner waterpool to methylviologen (MV2+) in the outer aqueous solution was driven by the irradiation of pyrene derivatives embedded in the vesicle bilayers. The initial rate of MV2+ reduction is dependent on the substituent group of the pyrenyl ring; a hydrophilic functional group linked with the pyrenyl ring by a short methylene chain acts as a sensitizer for the electron transport. Mechanistic studies using (1-pyrenyl)alkanoic acids (1a-c) as sensitizers suggest that the electron transport is mainly initiated by the reductive quenching of the singlet excited state of the pyrene by Asc- and proceeds by a mechanism involving electron exchange between the pyrenes located at the inner and outer interface across the vesicle bilayer. We designed and synthesized novel unsymmetrically substituted pyrenes having both a hydrophilic group linked by a short methylene chain and a hydrophobic long alkyl group (5a-c), which acted as excellent sensitizers for the electron transport across vesicle bilayers.
authors.affiliation: Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo 153-8902, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Mizushima
authors.forename: Asako
authors.initials: A
authors.lastname: Yoshida
authors.forename: Akitomo
authors.initials: A
authors.lastname: Harada
authors.forename: Yu
authors.initials: Y
authors.lastname: Yoneda
authors.forename: Tomiaki
authors.initials: T
authors.lastname: Minatani
authors.forename: Shigeru
authors.initials: S
authors.lastname: Murata
mesh_terms: D001205:Ascorbic Acid / Q000737:chemistry; D004579:Electron Transport; D005453:Fluorescence; D007700:Kinetics; D008027:Light; D008051:Lipid Bilayers / Q000737:chemistry* / Q000528:radiation effects; D019906:Nuclear Magnetic Resonance, Biomolecular; D010269:Paraquat / Q000737:chemistry; D010777:Photochemistry; D017319:Photosensitizing Agents; D011721:Pyrenes / Q000737:chemistry*; D012542:Scattering, Radiation
chemical_list: D008051:Lipid Bilayers; D017319:Photosensitizing Agents; D011721:Pyrenes; D010269:Paraquat; D001205:Ascorbic Acid