Wang Ye, Shi Ying, Cong Lin, Li Hui
Institute of Atomic and Molecular Physics, Jilin University, Changchun 130012, China.
Institute of Atomic and Molecular Physics, Jilin University, Changchun 130012, China.
Spectrochim Acta A Mol Biomol Spectrosc. 2015 Feb 25;137:913-8. doi: 10.1016/j.saa.2014.09.024. Epub 2014 Sep 22.
Time-dependent density functional theory method at the def-TZVP/B3LYP level was employed to investigate the intramolecular and intermolecular hydrogen bonding dynamics in the first excited (S1) state of 4'-dimethylaminoflavonol (DMAF) monomer and in ethanol solution. In the DMAF monomer, we demonstrated that the intramolecular charge transfer (ICT) takes place in the S1 state. This excited state ICT process was followed by intramolecular proton transfer. Our calculated results are in good agreement with the mechanism proposed in experimental work. For the hydrogen-bonded DMAF-EtOH complex, it was demonstrated that the intermolecular hydrogen bonds can induce the formation of the twisted intramolecular charge transfer (TICT) state and the conformational twisting is along the C3-C4 bond. Moreover, the intermolecular hydrogen bonds can also facilitate the intermolecular double proton transfer in the TICT state. A stepwise intermolecular double proton transfer process was revealed. Therefore, the intermolecular hydrogen bonds can alter the mechanism of intramolecular charge transfer and proton transfer in the excited state for the DMAF molecule.
采用def-TZVP/B3LYP水平的含时密度泛函理论方法，研究了4'-二甲基氨基黄酮醇（DMAF）单体及其乙醇溶液第一激发态（S1）下的分子内和分子间氢键动力学。在DMAF单体中，我们证明了分子内电荷转移（ICT）发生在S1态。这种激发态ICT过程之后是分子内质子转移。我们的计算结果与实验工作中提出的机理高度吻合。对于氢键连接的DMAF-EtOH复合物，证明了分子间氢键可诱导扭曲分子内电荷转移（TICT）态的形成，且构象扭曲沿C3-C4键进行。此外，分子间氢键还可促进TICT态下的分子间双质子转移。揭示了一个逐步的分子间双质子转移过程。因此，分子间氢键可改变DMAF分子激发态下分子内电荷转移和质子转移的机理。
