Effects of Intermolecular Hydrogen Bonding and Solvation on Enol-Keto Tautomerism and Photophysics of Azomethine-BODIPY Dyads
Effects of Intermolecular Hydrogen Bonding and Solvation on Enol-Keto Tautomerism and Photophysics of Azomethine-BODIPY Dyads
复制标题
分子间氢键和溶剂化对甲亚碱-BODIPY二元体烯醇-酮互变异构和光物理的影响
DOI：
10.1021/acs.jpcb.1c04776
复制
发表时间：
2021-08-10
影响因子：
3.3
通讯作者：
Zhou, Panwang
中科院分区：
文献类型：
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作者：
Jiang, Gaoshang;Tang, Zhe;Zhou, Panwang
硼二吡咯亚甲基衍生物（BODIPYs）是一类具有优异光物理性质的分子，可应用于各个领域。本工作基于时间依赖密度泛函理论（TD-DFT）方法研究了两种偶氮甲碱-BODIPY二联体在不同溶剂中的荧光性质。势能曲线（PEC）表明，极性质子溶剂和增强的π共轭效应可以降低质子转移（PT）势垒，导致NA-BODIPY在甲醇中的主要构型为酮型，而NA-BODIPY在甲苯中和SA-BODIPY在甲醇和甲苯中的主要构型为烯醇型。这两种化合物的酮形式在激发态下具有扭曲分子内电荷转移（TICT）衰变途径，该途径由优化的扭曲构型和TICT过程的适当势垒确定，而烯醇形式的扭曲构型不存在。 TICT 成功地与酮形式的激发态质子转移 (ESIPT) 竞争，导致 NA-BODIPY 在甲醇中荧光猝灭。该工作为烯醇酮互变异构以及TICT和ESIPT竞争力对BODIPYs光物理性质的影响提供了新思路，有望为新型BODIPY功能分子的设计提供指导。
Boron-dipyrromethene derivatives (BODIPYs) are a category of molecules with excellent photophysical properties and can be applied to various fields. This work investigates the fluorescent properties of two azomethine-BODIPY dyads in different solvents based on the time-dependent density functional theory (TD-DFT) method. The potential energy curves (PECs) show that the polar protic solvent and the enhanced pi-conjugation effect can lower the proton-transfer (PT) barriers, causing the main configuration of NA-BODIPY in methanol to be the keto form, while the main configuration of NA-BODIPY in toluene and SA-BODIPY in methanol and toluene is the enol form. The keto forms of the two compounds possess the twisted intramolecular charge transfer (TICT) decay pathway in the excited state identified by the optimized twisted configurations and the appropriate barriers of the TICT process, whereas the twisted configurations of the enol forms are nonexistent. TICT successfully competes with excited-state proton transfer (ESIPT) of the keto form, which leads to the fluorescence quenching of NA-BODIPY in methanol. This work provides new ideas for the influence of enol-keto tautomerism and the competitiveness of TICT and ESIPT on the photophysical properties of BODIPYs and is expected to provide guidance for the design of new BODIPY functional molecules.