Shen Zibo, Liu Chang, Zhao Jinfeng, Chen Jiahe
College of Physical Science and Technology, Shenyang Normal University, Shenyang 110034, China.
J Phys Chem A. 2025 Jun 12;129(23):5098-5106. doi: 10.1021/acs.jpca.5c02523. Epub 2025 May 28.
In this work, the influence of solvent polarities on the excited-state intramolecular proton transfer (ESIPT) process of BP(OH)DCEt fluorophore has been systematically investigated in three solvents with distinct polarities (acetonitrile, chloroform, and cyclohexane) through DFT and TDDFT methodologies. We mainly focus on elucidating the related excited-state double proton transfer (ESDPT) mechanism in BP(OH)DCEt. We analyze geometric configurations, infrared (IR) vibrational spectra, and core-valence bifurcation (CVB) indexes to verify the enhancement of the dual hydrogen bonds in the excited state. Meanwhile, we detected the HOMO and LUMO orbitals to investigate the effects of charge redistribution on the ESIPT/ESDPT process. The reactional potential energy surfaces (PESs) are scanned and transition state (TS) forms are searched to testify the stepwise ESDPT mechanism for BP(OH)DCEt systems in three solvents. We also propose that the increase of solvent polarity can promote the occurrence of the step-by-step ESDPT reaction processes for the BP(OH)DCEt system based on the calculated S-state potential energy barriers in the surrounding environment.
在本工作中，通过密度泛函理论（DFT）和含时密度泛函理论（TDDFT）方法，在三种极性不同的溶剂（乙腈、氯仿和环己烷）中系统研究了溶剂极性对BP(OH)DCEt荧光团激发态分子内质子转移（ESIPT）过程的影响。我们主要致力于阐明BP(OH)DCEt中相关的激发态双质子转移（ESDPT）机制。我们分析几何构型、红外（IR）振动光谱和核价分叉（CVB）指数，以验证激发态中双氢键的增强。同时，我们检测最高占据分子轨道（HOMO）和最低未占据分子轨道（LUMO），以研究电荷重新分布对ESIPT/ESDPT过程的影响。扫描反应势能面（PESs）并寻找过渡态（TS）形式，以验证BP(OH)DCEt体系在三种溶剂中的分步ESDPT机制。基于计算得到的周围环境中的S态势能垒，我们还提出溶剂极性的增加可以促进BP(OH)DCEt体系分步ESDPT反应过程的发生。
