FLAVIN-PHOTOSENSITIZED MONOMERIZATION OF DIMETHYLTHYMINE CYCLOBUTANE DIMER IN THE PRESENCE OF MAGNESIUM PERCHLORATE |
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| Authors: | Kunihito Miyake Yasuhiro Masaki Ikuya Miyamoto Shozo Yanagida Takeshi Ohno Akio Yoshimura Chyongjin Pac |
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| Institution: | Department of Chemical Process Engineering, Faculty of Engineering, Osaka University, Suita, Osaka 565, Japan;Chemistry Department, College of General Education, Osaka University, Toyonaka, Osaka 560, Japan;Kawamura Institute of Chemical Research, Sakado, Sakura, Chiba 285, Japan |
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| Abstract: | We have investigated the photosensitized monomerization of the cis,syn -cyclobutane dimer of 1,3-di-methylthymine using riboflavin tetraacetate and a 5-deazaflavin derivative as photosensitizer. Although little monomerization of the dimer is induced by photoexcitation of the flavins in the absence of any additives, the flavins can function as an efficient photosensitizer in the presence of magnesium perchlorate. Mechanistic studies involving spectroscopic, quantum-yield and flash-photolysis measurements demonstrated that the photosensitized monomerization exclusively proceeds through electron transfer from the dimer to the triplet flavins complexed with Mg2+. The effects of magnesium perchlorate are compared with those on the chloranil-photosensitized monomerization and also with the effects of HClO4 on the flavin-photosensitized reaction. |
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