| Co-Investigator(Kenkyū-buntansha) |
NISHIYAMA Katsuhiko Fac. of Eng., Kumamoto University, Associate Professor, 工学部, 講師 (10202243)
MATSUMOTO Yasumichi Graduate School of Science and Technology, Kumamoto University, Professor, 大学院・自然化学研究科, 教授 (80114172)
TANIGUCHI Isao Fac. of Eng., Kumamoto University, Professor, 工学部, 教授 (90112391)
濱田 泰輔 熊本大学, 工学部, 助手 (10253717)
SUGIMOTO Manabu Graduate School of Science and Technology, Kumamoto University, Associate Professor, 大学院・自然化学研究科, 講師 (80284735)
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| Research Abstract |
We newly synthesized chiral photosensitizers, Δ-[Ru(menbpy)ィイD23ィエD2]ィイD12+ィエD1 (menbpy=4,4'-bis(1R,2S,5R)-(-)menthoxycarbonyl}-2,2'-bipyridine), Δ-[Ru(phenebpy)ィイD23ィエD2]ィイD12+ィエD1 (phenebpy=4,4'-bis(1-phenethylaminocarbonyl)-2,2'-bipyridine), [Cu(tmdcbpy)(PRィイD23ィエD2)ィイD22ィエD2]ィイD12+ィエD1 (tmdcbpy=4,4'-6,6'-tetramethyl-5,5'-bis(S)-(-)-1-phenylcarbamoyl-2,2'-bipyridine).These photosensitizers do not cause photoracemization and their photoexcited states (triplet MLCT excited state) are long-lived, (2) Δ-[Ru(menbpy)ィイD23ィエD2]ィイD12+ィエD1 performs effectively stereoselective photoreduction of [Co(acac)ィイD23ィエD2] under visible light irradiation. [Cu(tmdcbpy)(PPhィイD23ィエD2)]ィイD1+ィエD1 also performs stereoselective photoreduction of [Co(edta)]ィイD1-ィエD1 with significantly large enantiomer excess (60% at l0% conversion), under near-UV light irradiation. On the other hand, [Ru(phenebpy)ィイD23ィエD2]ィイD12+ィエD1 cannot perform stereoselective photoreduction. (3) An anionic chiral Cu(I) complex, [Cu(tmdcb
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py){PPhィイD22ィエD2(m-CィイD26ィエD2HィイD24ィエD2SOィイD23ィエD2ィイD1-ィエD1)}ィイD22ィエD2]ィイD1-ィエD1, performs photoreduction of [Co(edta)]ィイD1-ィエD1 with less reactivity and smaller stereoselectivity. The reaction mechanism is different from that of photoreduction of [Co(edta)]ィイD1-ィエD1 by [Cu(tmdcbpy)(PPhィイD23ィエD2)ィイD22ィエD2]ィイD1+ィエD1. The former proceeds through dynamic quenching mechanism, while the latter through static quenching mechanism. (4) We succeeded the photoasymmetric synthesis of [Co(edta)]ィイD1-ィエD1 from CoXィイD22ィエD2 (X=AcOィイD1-ィエD1, NOィイD23ィエD2ィイD1-ィエD1 etc.) and LィイD24ィエD2edta (L=H or Na) with [Cu(tmdcbpy)(PPhィイD23ィエD2]ィイD1+ィエD1 under near-UV light irradiation. Δ-[Co(edta)]ィイD1-ィエD1 is formed in excess when NaィイD24ィエD2edta was used, while ∧-[Co(edta)]ィイD1-ィエD1 is formed when HィイD24ィエD2edta was used. (5) Photoderacemization of [Co(acac)ィイD23ィエD2] was successfully carried out with Δ-[Ru(menbpy)ィイD23ィエD2]ィイD12+ィエD1 in acetonitrile-water under visible light irradiation. The reaction mechanism was elucidated. (6) Stereoselective photoreduction of chiral viologen was successfully performed with Δ-[Ru(menbpy)ィイD23ィエD2]ィイD12+ィエD1 and analysis based on Marcus theory was presented. Less
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