理论研究4′-甲氧基-3-羟基黄酮的激发态分子内质子转移机制

THEORETICAL STUDY ON THE EXCITED STATE INTRAMOLECULAR PROTON TRANSFER MECHANISM OF 4′-METHOXY-3-HYDROXYFLAVONE

4′-甲氧基-3-羟基黄酮(4M3HF)具有显著的质子转移特性.本文基于密度泛函理论在甲醇溶液中对4M3HF的激发态分子内质子转移(ESIPT)进行了研究.通过分析4M3HF的前线分子轨道、约化密度梯度函数以及红外振动光谱,发现该分子的氢键相互作用在第一激发态有显著的增强.计算得到的吸收光谱和荧光光谱与实验数据是相吻合的.此外,为了更清楚的描述质子转移的反应路径,4M3HF的势能曲线是被获得.结果表明,4M3HF仅能发生激发态质子转移而不能发生基态质子转移,而反质子转移则发生在基态.

4′-methoxy-3-hydroxyflavone(4M3HF)has significant proton transfer properties.In this paper,the excited state intramolecular proton transfer(ESIPT)of 4M3HF in methanol solution was studied based on density functional theory in methanol solution.By analyzing the frontier molecular orbitals,reduced density gradient(RDG)functions,and infrared vibrational spectra,it was found that the hydrogen bonding interaction of 4M3HF was significantly enhanced in the first excited state.The calculated absorption and fluorescence spectra are in agreement with the experimental data.Furthermore,in order to more clearly describe the reaction path of proton transfer,the potential energy curves of 4M3HF was obtained.The results show that 4M3HF can only undergo excited state proton transfer without ground state proton transfer,while reverse proton transfer occurs in the ground state.