title: Driving force dependence of charge separation and recombination processes in dyads of nucleotides and strongly electron-donating oligothiophenes.
abstract: Charge transfer in DNA has attracted great attention of scientists because of its importance in biological processes. However, our knowledge on excess-electron transfer in DNA still remains limited in comparison to numerous studies of hole transfer in DNA. To clarify the dynamics of excess-electron transfer in DNA by photochemical techniques, new electron-donating photosensitizers should be developed. Herein, a terthiophene and two 3,4-ethylenedioxythiophene oligomers were used as photosensitizers in dyads including natural nucleobases as electron acceptors. The charge separation and recombination processes in the dyads were investigated by femtosecond laser flash photolysis, and the driving force dependence of these rate constants was discussed on the basis of the Marcus theory. From this study, the conformation effect on charge recombination process was found. We expect that 3,4-ethylenedioxythiophene oligomers are useful in investigation of excess-electron-transfer dynamics in DNA.
authors.affiliation: The Institute of Scientific and Industrial Research (SANKEN), Osaka University , Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan.
authors.forename: Shih-Hsun
authors.initials: SH
authors.lastname: Lin
authors.forename: Mamoru
authors.initials: M
authors.lastname: Fujitsuka
authors.forename: Mayuka
authors.initials: M
authors.lastname: Ishikawa
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Majima
mesh_terms: D004247:DNA / Q000737:chemistry; D019281:Dimerization; D004579:Electron Transport; D007700:Kinetics; D009711:Nucleotides / Q000737:chemistry*; D017319:Photosensitizing Agents / Q000737:chemistry; D013876:Thiophenes / Q000737:chemistry*
chemical_list: D009711:Nucleotides; D017319:Photosensitizing Agents; D013876:Thiophenes; D004247:DNA