Unified understanding on the changes in vibrational spectra arising from responses to external electric field and intermolecular interactions of hydrogen-bonded systems

2019 Fiscal Year Final Research Report

• Project/Area Number: 16K05652
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Physical chemistry
• Research Institution: Shizuoka University
• Principal Investigator: TORII Hajime 静岡大学, 工学部, 教授 (80242098)
• Project Period (FY): 2016-04-01 – 2020-03-31
• Keywords: 水素結合 / 電場 / 分子間相互作用 / 振動スペクトル / 核磁気共鳴

Outline of Final Research Achievements

Theoretical analysis has been conducted on how the hydration-induced changes in the vibrational frequencies and IR intensities depend on the hydrogen-bond configurations and how they are correlated to the vibrational Stark effect and the changes in the NMR chemical shifts, focusing on some functional groups that are sensitive to intermolecular interactions such as the CN group of nitrile compounds and the ligands to the heme, including the electronic structural aspects of these groups. For the CN group of a nitrile compound, it has been clarified that, contrary to some previous discussions, the hydration-induced apparently peculiar changes in the stretching frequency and the NMR chemical shift arise from the spatially inhomogeneous nature of electrostatic environment. Together with the cases of other functional groups, a unified understanding on the changes in the spectroscopic properties has been obtained, and a way to constructing electrostatic interaction models has been proposed.

Free Research Field

理論化学

Academic Significance and Societal Importance of the Research Achievements

分子間相互作用による分光学的性質の変化について，従来から特異だと考えられてきたものを含めて，統一的な理解とモデル構成法を示すことができた。この結果は，さらに多様な官能基について静電相互作用モデルを整備することにより，凝縮相系における相互作用の様相を明らかにすることができるという道筋を開いたことになる。これは，多くの広く興味を持たれている凝縮相系での化学プロセスの詳細を分光学的手法で解明する上で，重要な寄与をするものと考えられる。