| Project/Area Number |
03101004
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| Research Category |
Grant-in-Aid for Specially Promoted Research
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| Allocation Type | Single-year Grants |
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| Research Institution | University of Tsukuba |
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Principal Investigator |
TOKUMARU Katsumi Department of Chemistry University of Tsukuba Professor, 化学系, 教授 (60011491)
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| Co-Investigator(Kenkyū-buntansha) |
KARATSU Takashi College of Arts and Sciences Chiba University Associate Professor, 教養部, 助教授 (70214575)
KURIYAMA Yasunao Department of Chemistry University of Tsukuba Research Associate, 化学系, 助手 (50225273)
TSUCHIYA Masahiro Department of Chemistry University of Tsukuba Research Associate, 化学系, 助手 (60227436)
ARAI Tatsuo Department of Chemistry University of Tsukuba Assistant Professor, 化学系, 講師 (50151139)
KIKUCHI Osamu Department of Chemistry University of Tsukuba Professor, 化学系, 教授 (30015771)
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| Project Period (FY) |
1991 – 1993
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| Keywords | Photochemical one-way isomerization / Double bond / Amplification of the effect of photon / Potential energy surface / Triplet energy / Rotational isomerization / Intramolecular hydrogen bond / Cation radical |
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| Research Abstract |
This project intended to develop our new discovery that substitution of a large pi-electronic system on a carbon-carbon double bond leads to photochemical one-way isomerization from the cis to trans isomer proceeding through a quantum chain process inducing the isomerization of as much as tens of the cis molecules by the absorption of one photon. This is remarkably contrasting to the hitherto accepted concept that the double bond would generally undergo mutual isomerization between the cis and trans isomers.
We revealed structural features to determine the mode of isomerization as well as the potential energy surface of the one-way isomerization. Furthermore, we explored how the action of one photon can be amplified to effect the behavior of hundreds of molecules.
(1) An olefin with a perylene ring on the C=C double bond underwent one-way cis->trans isomerization as an adiabatic process overcoming an activation barrier of 6.6 kcal mol^<-1>.
(2) Trans-2-stryrylanthracene underwent one-way
… More
internal rotation from the s-trans to s-cis isomer in the excited triplet state.
(3) 1-Styrylazulene underwent one-way cis->trans isomerization in the excited triplet state.
(4) N-Methoxy-1-(2-anthryl)-ethanimine (NA) underwent one-way cis->trans isomerization around the double bond in the excited triplet state, while intermal rotation took place from s-trans to s-cis in the excited singlet as well as in the triplet state. The effect of substitution position of the anthracene nucleus on the photochemical behavior of imines was also studied.
(5) Substitution of a phenyl group in stilbene by a ferrocenyl group remarkably suppressed the photochemical isomerization between the cis- and trans-isomers.
(6) Polar solvents as well as polar substituents affected the mechanism and the efficiency of cis-trans isomerization of 1-styrylpyrenes and 2-styrylanthracenes.
(7) 1-(2-Pyrrolyl)-2-(2-quinolyl)ethene underwent photochemical mutual isomerization, but a novel intramolecular hydrogen atom transfer to give a tautomer was observed on irradiation of the cis isomer.
(8) The efficiency of photoisomerization of bilirubin strongly depended on the properties of solvent and the source of serum albumin.
(9) The calculated potential energy surfaces of cis->trans isomerization in the excited state and in the form of cation radical qualitatively agreed with the experimental results. Less
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