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.

An electron transport from an electron donor entrapped into inner waterpool to an electron acceptor in outer aqueous solution across vesicle bilayers was sensitized by pyrene derivatives incorporated in the vesicle walls, although the sensitizer ability was very dependent on the substituent group on the pyrenyl ring. The newly designed pyrenes having both a hydrophilic group linked by short methylene chain and a hydrophobic long alkyl group were found to act as excellent sensitizers.

Via Pd-coupling chemistry the compounds (I) are prepared and their physicochemical behavior is investigated. (I) are excellent sensitizers for an electron transport across vesicle bilayers. -(YOSHIDA, A.; HARADA, A.; MIZUSHIMA, T.; MURATA*, S.; Chem. Lett. 32 (2003) 1, 68-69; Dep. Basic Sci., Univ. Tokyo, Meguro, Tokyo 153, Japan; Eng.) -K. Schneider 23-025