气相水杨酸激发态分子内质子转移特性分析

采用密度泛函理论(DFT)和含时密度泛函理论(TD-DFT)研究了气相水杨酸(SA)分子的激发态氢键动力学过程。通过对水杨酸分子基态和激发态结构的优化,以及对其稳态吸收和发射光谱特性、前线分子轨道、红外振动光谱和势能曲线的计算分析,阐明水杨酸分子内质子转移可在激发态下自发地发生,导致其激发态可存在烯醇式和酮式两种异构体结构,并揭示了这种质子转移源于分子内电荷转移的激发态氢键的加强机制。

Analysis of gas salicylic acid excited state intramolecular proton transfer characteristics

The excited state hydrogen bond dynamics process of gas salicylic acid molecular is investigated using density functional theory (DFT) and time-dependent density functional theory (TD-DFT).The molecular structure at ground state and excited state are located, and the steady state absorption and emission spectra, the frontier molecular orbitals, IR vibrational spectra and potential energy curves are analyzed. Results indicate that intramolecular proton transfer can occur spontaneously in the excited state, which leads to the existence of enol and keto two isomers for the excited state salicylic acid molecular. The proton transfer is shown to originate from the excited state hydrogen bond strengthening mechanism caused by intramolecular charge transfer.