Ultrafast dynamics of dual fluorescence of 2-(2′-hydroxyphenyl) benzothiazole and its derivatives by femtosecond transient absorption spectroscopy
Ultrafast dynamics of dual fluorescence of 2-(2′-hydroxyphenyl) benzothiazole and its derivatives by femtosecond transient absorption spectroscopy
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DOI：
10.1016/j.jlumin.2022.118922
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发表时间：
2022-04
影响因子：
3.6
通讯作者：
Yonggang Yang;Qi Zhang;Yang Liu;Zhinan Jiang;Chaochao Qin;Kai Jiang;Yufang Liu
中科院分区：
文献类型：
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作者：
Yonggang Yang;Qi Zhang;Yang Liu;Zhinan Jiang;Chaochao Qin;Kai Jiang;Yufang Liu
利用飞秒瞬态吸收光谱研究了2-（2′-羟基苯基）苯并噻唑（HBT）和2-（2′-羟基苯基）苯并恶唑（HBO）分子的双荧光行为.在fs-TA光谱中，HBT的稳态荧光（515 nm）出现在受激发射区，另一个荧光（363 nm）被强激发态吸收信号所覆盖。从O-H N到O-H S构象扭转的大能垒（25.06 kcal/mol）表明在S1态几乎不发生构象扭转，这也得到了与实验结果不一致的光谱行为的支持.同时，HBT的非绝热动力学研究表明，质子从Enol到Keto的转移（PT）发生在115 fs，这与fs-TA的117.2 fs结果一致。酮型HBT的荧光（493 nm）与实验结果（515 nm）一致，另一个荧光（363 nm）来自烯醇型HBT。结合良好的能垒（1.68 kcal/mol），这些结果表明，在fs时间尺度上发生的PT是HBT双荧光的主要因素。与HBT相比，高压氧具有更高的能垒（3.74 kcal/mol）和更长的PT时间（164.7 fs）。fs-TA光谱和理论模拟的结合提供了深入了解HBT和HBO的荧光动力学。
The dual fluorescence behaviors of 2-(2′-Hydroxyphenyl) benzothiazole (HBT) and 2-(2′-hydroxyphenyl) benzoxazole (HBO) molecules are studied by femtosecond transient absorption (fs-TA) spectroscopy. The steady-state fluorescence (515 nm) of HBT appears in the stimulated emission region in fs-TA spectroscopy, and the other fluorescence (363 nm) is covered by the strong excited state absorption signal. The large energy barrier (25.06 kcal/mol) of conformational torsion from O–H⋯N to O–H⋯S form show that the torsion is hardly to occur in the S1state, which is also supported by the inconsistent spectra behaviors with the experimental results. Meanwhile, the nonadiabatic dynamics of HBT shows that the proton transfer (PT) from Enol to Keto occurs in 115 fs, which is consistent with the result of fs-TA in 117.2 fs. The fluorescence (493 nm) of the Keto form of HBT is consistent with experimental result (515 nm), and the other fluorescence (363 nm) comes from the Enol form of HBT. Together with favorable energy barrier (1.68 kcal/mol), these results demonstrate that the PT occurred in fs timescale is the main factor for dual fluorescence of HBT. Compared to HBT, HBO has higher energy barrier (3.74 kcal/mol) and longer PT time (164.7 fs). The combination of fs-TA spectroscopy and theoretical simulation provides insight to understand the fluorescent dynamics of HBT and HBO.