Yang Dapeng, Yang Guang, Jia Min, Song Xiaoyan, Zhang Qiaoli, Zhang Tianjie, Gao Haiyan
School of Mathematics and Statics, North China University of Water Resources and Electric Power Zhengzhou 450046 China
State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences Dalian 116023 China.
RSC Adv. 2018 Aug 21;8(52):29662-29669. doi: 10.1039/c8ra05945d. eCollection 2018 Aug 20.
At the TD-B3LYP/TZVP/IEFPCM theory level, we have theoretically studied the excited-state intramolecular proton coupled charge transfer (ESIPCCT) process for both 4'-,-diethylamino-3-hydroxyflavone (3HFN) and 2-{[2-(2-hydroxyphenyl)benzo[]oxazol-6-yl]methylene}malononitrile (diCN-HBO) molecules. Our calculated hydrogen bond lengths and angles sufficiently confirm that the intramolecular hydrogen bonds O-H⋯O and O-H⋯N formed at the S states of 3HFN and diCN-HBO should be significantly strengthened in the S state, which is further supported by the results obtained based on the analyses of infrared spectra shifts, molecular orbitals and charge density differences maps. The significant strengthening of intramolecular hydrogen bonds O-H⋯O and O-H⋯N upon photoexcitation should facilitate the ESIPCCT process of the two title molecules. The scanned potential energy curves and confirmed excited-state transition states for both 3HFN and diCN-HBO show that the proton can be easily transferred from O to O (N for diCN-HBO) through the strengthened intramolecular hydrogen bonds upon photoexcitation to the S state.
在TD-B3LYP/TZVP/IEFPCM理论水平下，我们从理论上研究了4'-,-二乙氨基-3-羟基黄酮（3HFN）和2-{[2-(2-羟基苯基)苯并[]恶唑-6-基]亚甲基}丙二腈（diCN-HBO）分子的激发态分子内质子耦合电荷转移（ESIPCCT）过程。我们计算得到的氢键长度和角度充分证实，3HFN和diCN-HBO在S态形成的分子内氢键O-H⋯O和O-H⋯N在S态应显著增强，基于红外光谱位移、分子轨道和电荷密度差图的分析结果进一步支持了这一点。光激发时分子内氢键O-H⋯O和O-H⋯N的显著增强应有助于两个标题分子的ESIPCCT过程。3HFN和diCN-HBO的扫描势能曲线和确认的激发态过渡态表明，光激发到S态时，质子可以通过增强的分子内氢键容易地从O转移到O（diCN-HBO为N）。
