Investigation of a Series of 2-(2′-Hydroxyaryl)benzazole Derivatives: Photophysical Properties, Excited-State Intramolecular Proton-Transfer Reactions, and Observation of Long-Lived Triplet Excited States
Investigation of a Series of 2-(2′-Hydroxyaryl)benzazole Derivatives: Photophysical Properties, Excited-State Intramolecular Proton-Transfer Reactions, and Observation of Long-Lived Triplet Excited States
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一系列 2-(2-羟基芳基)苯并唑衍生物的研究：光物理性质、激发态分子内质子转移反应以及长寿命三重态激发态的观察
DOI：
10.1021/acs.jpcb.1c05798
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Phillips, David Lee
中科院分区：
文献类型：
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作者：
Li, Yuanchun;Bai, Xueqin;Liang, Runhui;Zhang, Xiting;Nguyen, Yen H.;VanVeller, Brett;Du, Lili;Phillips, David Lee
激发态分子内质子转移（ESIPT）因其在许多领域的重要应用而受到广泛关注。本文采用稳态和时间分辨吸收光谱实验以及DFT/TD-DFT计算方法研究了2-（2′-羟基苯基）苯并恶唑（HBO）及其衍生物（化合物1 -3）的光物理性质和光化学反应机理。化合物1 - 3由于具有较大的π共轭骨架，与HBO相比，其吸收峰红移，荧光峰蓝移。化合物3的ESIPT过程为烯醇/酮平衡型，具有双发射。有趣的是，对于化合物1和2，仅观察到烯醇形式的发射，这表明ESIPT过程被强烈抑制。这些结果表明，在羟基苯基环上引入吸电子基团如噻二唑和吡嗪（化合物1和2）明显抑制了激发态的质子转移过程。而对于用邻菲咯环修饰的化合物3，ESIPT过程很少增加，因为与HBO相比，化合物3的有效共轭降低。这里的工作提供了基本的见解，可能是有用的设计新的ESIPT分子在未来。
Excited state intramolecular proton transfer (ESIPT) has drawn much attention for its important applications in a variety of areas. Here, the steady-state and time-resolved absorption spectroscopic experiments as well as DFT/TD-DFT calculations are employed to study the photophysical properties and photochemical reaction mechanisms of 2-(2′-hydroxyphenyl) benzoxazole (HBO) and selected derivatives (compounds1–3). Because of their larger π-conjugation framework, compounds1–3display red-shifted absorbance but blue-shifted fluorescence compared withHBO. A fast ESIPT process is observed directly forHBOwhile compound3has an enol/keto equilibrium type of ESIPT that exhibits dual emission. Interestingly, only the emission of the enol form is observed for compounds1and2which suggests that the ESIPT process is strongly inhibited. These results indicate the decoration with electron-withdrawing groups such as thiadiazol and pyrazine on the hydroxyphenyl ring (compounds1and2) apparently suppresses the proton-transfer processes in their excited states. Whereas the ESIPT process is rarely increased for compound3that modified with the phenanthrol ring, because the effective conjugation is reduced for compound3compared withHBO. The work here provides fundamental insights that may be useful for designing novel ESIPT molecules in the future.