3发色团激发态分子内质子转移机理的研究

采用密度泛函(DFT)和含时密度泛函理论(TDDFT)方法对一种新合成的发色团(3)在非质子性溶剂DMSO中的激发态分子内质子转移机制进行了理论研究.基于3发色团的基态和激发态优化结构,计算得到了该发色团中与氢键相关的键长和键角的大小,以及与氢键相连接的O-H键红外振动光谱,发现分子内氢键在激发态下有增强的趋势.理论计算得到的吸收谱和荧光谱的峰值与实验测得的结果吻合得很好,证明了所采用的理论方法的正确性与合理性.最终,通过对该发色团的分子内电荷转移与电荷分布的分析,证实了激发态分子内质子转移发生的可能性,并说明了其转移过程的发生机制.

The Investigation of Excited-State Intramolecular Proton Transfer Mechanism of 3 Chromophore

The density functional theory (DFT) and time-dependent density functional theory (TDDFT) were employed to investigate the excited-state intramolecular proton transfer (ESIPT) mechanism of 3 chromophore in the aprotic DMSO solvent. The intramolecular hydrogen bond was proved to be strengthened through the analyzing of calculated primary bond lengths, angles, and the IR vibrational spectra of the molecule in the ground and excited states. The electronic spectra observed at the previous experiment were reproduced well through the calculated vertical excited energy, indicating the rationality and correctness of the methods adopted in our calculation. The analysis of the intramolecular charge transfer via the frontier molecular orbitals predicted the reaction of the ESIPT process. As a consequence, the ESIPT mechanism of the 3 chromophore is elucidated definitely.