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Structure and Electron Configuration of Imidazole-2-carboxaldehyde and Its Excited Triplet: Resonance Raman and Transient Absorption Spectroscopy and DFT Calculation Investigations
The Journal of Physical Chemistry A ( IF 2.7 ) Pub Date : 2023-11-16 , DOI: 10.1021/acs.jpca.3c06750
Baohua Huang 1 , Tengshuo Zhang 2 , Xiaoyuan Zhao 1 , Yuwei Yuan 1 , Yong Du 3 , Jiadan Xue 1, 4
Affiliation  

Imidazole-2-carboxaldehyde (IC) can be generated in atmospheric waters and absorbs solar radiation in the near UV region to produce its excited triplet state (3IC), which contributes to the formation of a secondary organic aerosol (SOA). The photoreactivity of IC is significantly influenced by its surroundings, such as water and acidic environment, because IC is capable of transforming into gem-diol under above conditions. Meanwhile, the electron configuration of 3IC is critical in elucidating the reaction mechanism of 3IC with other anthropogenic and biogenic volatile organic compounds (VOCs). In this study, steady-state and time-resolved resonance Raman as well as transient absorption spectroscopic experiments were conducted to provide vibrational and kinetic information on IC and 3IC in the presence of water and acid conditions. Using density functional theory (DFT) calculations, the H-bonding at the carbonyl O was confirmed and the hydrated structure of IC and 3IC was determined. 1,4-Cyclohexadiene is a good hydrogen donor, and it has a second-order rate constant of ∼107 M–1 s–1 toward 3IC. The results of CASSCF calculations suggest that the hydrogen abstraction may involve the transition from the ππ* to nπ* triplet state via the surface-crossing point.

中文翻译:

咪唑-2-甲醛及其激发三重态的结构和电子构型:共振拉曼、瞬态吸收光谱和DFT计算研究

咪唑-2-甲醛(IC)可以在大气水中产生,并吸收近紫外区域的太阳辐射产生其激发三重态(3 IC),这有助于形成二次有机气溶胶(SOA)。IC的光反应性受周围环境如水和酸性环境的显着影响,因为IC在上述条件下能够转化为宝石二醇。同时, 3 IC的电子构型对于阐明3 IC 与其他人为和生物挥发性有机化合物(VOC)的反应机制至关重要。在这项研究中,进行了稳态和时间分辨共振拉曼以及瞬态吸收光谱实验,以提供 IC 和3 IC 在水和酸条件下的振动和动力学信息。利用密度泛函理论(DFT)计算,证实了羰基O处的H键,并确定了IC和3 IC的水合结构。1,4-环己二烯是一种良好的氢供体,其二阶速率常数对于3 IC而言为∼10 7 M –1 s –1。CASSCF计算结果表明,夺氢可能涉及通过表面交叉点从ππ*到nπ*三重态的转变。
更新日期:2023-11-16
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