Relaxation mechanism of nucleobases and their derivatives in aqueous solution

2023 Fiscal Year Final Research Report

• Project/Area Number: 22K14647
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 32010:Fundamental physical chemistry-related
• Research Institution: Kyoto University
• Principal Investigator: Karashima Shutaro 京都大学, 理学研究科, 特定助教 (40890926)
• Project Period (FY): 2022-04-01 – 2024-03-31
• Keywords: 光電子分光 / 光反応ダイナミクス / フェムト秒レーザー

Outline of Final Research Achievements

We performed extreme ultraviolet photoelectron spectroscopy on the photoreaction dynamics of the nucleobase molecules and their derivatives in liquid water. The results show that only a few tens of percent at most remain in the electronically excited state on the picosecond scale, and most quickly relax to the electronic ground state. In addition, the reaction dynamics of molecules in the gas phase were studied. It has found that coordination to the 5-carbon atom has a critical effect on the efficiency of electronic relaxation by comparing the results of uracil, thymine (5-methyluracil), and 6-methyluracil.

Free Research Field

反応ダイナミクス

Academic Significance and Societal Importance of the Research Achievements

DNAやRNAの光化学反応は損傷や変異といった生命維持への脅威につながるため、光を吸収するアンテナ的役割を担う核酸塩基分子の光反応ダイナミクスの解明は非常に重要である。従来とは異なる実験手法（極端紫外光電子分光法）で研究することで、光反応過程における各電子状態の電子束縛エネルギー推移や反応収率を明らかとした。一方で過渡吸収分光法による過去研究結果との間では、反応収率において一部整合していない点も見られた。今後も検討・議論を重ねることで、核酸塩基分子の光反応機構の解明に向けて研究のさらなる発展が望まれる。