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2022 Fiscal Year Final Research Report

Molecular dynamics of ultrashort-lived tautomers as transient species of chemical reactions

Research Project

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Project/Area Number 19K05377
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeMulti-year Fund
Section一般
Review Section Basic Section 32010:Fundamental physical chemistry-related
Research InstitutionRitsumeikan University

Principal Investigator

Nagasawa Yutaka  立命館大学, 生命科学部, 教授 (50294161)

Project Period (FY) 2019-04-01 – 2023-03-31
Keywords超高速分光 / 時間分解分光 / 過渡吸収スペクトル / 光異性化 / 無輻射失活 / ソルバトクロミズム / 互変異性化 / コヒーレント振動
Outline of Final Research Achievements

The following two studies by femtosecond time-resolved transient absorption spectroscopy were published as peer reviewed papers.
1) A nonfluorescent solvatochromic dye, phenol blue, exhibits ultrafast nonradiative deactivation from the excited state. It was found that, in proton-donating solvents, when the absorbed light energy is released as heat during the nonradiative decay, the hydrogen bond with the solvent molecule is cleaved. [C. Ota, et al., J. Phys. Chem. B, 125, 10832 (2021)]
2) The photoisomerization reaction of indigo derivatives were studied, and it was clarified that the excited state of the cis-isomer is more unstable than that of the trans-isomer due to the Coulombic repulsion of adjacent C=O groups. Hence, the excited state lifetime of cis-form is shorter than that of the trans-form and the quantum yield of cis-to-trans isomerization is higher than that of the trans-to-cis isomerization. [Y. Kihara, et. al., J. Phys. Chem. B, 126, 3539 (2022)]

Free Research Field

物理化学

Academic Significance and Societal Importance of the Research Achievements

植物の光合成系では、光化学系Ⅱ反応中心において、水が酸化されて酸素が発生する。この際、水・アミノ酸残基間の水素結合がプロトン移動を媒介する。よって、光反応に付随した水素結合の挙動について検証することは非常に有意義な研究である。また、異性化反応は光合成とは直接の関連はないが、ハロバクテリアのの光エネルギー変換機構として、バクテリオロドプシンによるプロトンポンピングの素過程として重要である。現在、環境問題の観点から、火力や原子力に代わるエネルギー源の開発が急務となっているが、新たな効率的光エネルギー変換機構の開発には、光化学反応ダイナミクスの解明が重要であり、欠くことのできない基礎研究である。

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Published: 2024-01-30  

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