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Excess‐Electron Injection and Transfer in Terthiophene‐Modified DNA: Terthiophene as a Photosensitizing Electron Donor for Thymine, Cytosine, and Adenine
Author(s) -
Park Man Jae,
Fujitsuka Mamoru,
Kawai Kiyohiko,
Majima Tetsuro
Publication year - 2012
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201103663
Subject(s) - nucleobase , thymine , chemistry , cytosine , terthiophene , electron transfer , dna , photochemistry , electron donor , molecule , organic chemistry , biochemistry , catalysis
Excess‐electron transfer (EET) in DNA has attracted wide attention owing to its close relation to DNA repair and nanowires. To clarify the dynamics of EET in DNA, a photosensitizing electron donor that can donate an excess electron to a variety of DNA sequences has to be developed. Herein, a terthiophene (3T) derivative was used as the photosensitizing electron donor. From the dyad systems in which 3T was connected to a single nucleobase, it was revealed that 1 3T* donates an excess electron efficiently to thymine, cytosine, and adenine, despite adenine being a well‐known hole conductor. The free‐energy dependence of the electron‐transfer rate was explained on the basis of the Marcus theory. From the DNA hairpins, it became clear that 1 3T* can donate an excess electron not only to the adjacent nucleobase but also to the neighbor one nucleobase further along and so on. From the charge‐injection rate, the possibilities of smaller β value and/or charge delocalization were discussed. In addition, EET through consecutive cytosine nucleobases was suggested.