Mechanisms of Aggregation-Induced Emission and Photo/Thermal E/Z Isomerization of a Cyanostilbene Derivative: Theoretical Insights
Mechanisms of Aggregation-Induced Emission and Photo/Thermal E/Z Isomerization of a Cyanostilbene Derivative: Theoretical Insights
复制标题
DOI：
10.1021/acs.jpcc.8b02147
复制
发表时间：
2018-05
影响因子：
3.7
通讯作者：
Norifumi Yamamoto
中科院分区：
文献类型：
--
作者：
Norifumi Yamamoto
采用分子模拟方法研究了一种氰基二苯乙烯衍生物1-氰基-1，2-二-（4′-甲基联苯）乙烯（CN-MBE）的聚集诱导发光（AIE）。已知CN-MBE的E-形式表现出AIE，其在稀溶液中不发射，但在聚集态中变得高度发射，而其Z-形式即使在其结晶形式下也不发射。此外，在UV光照射下，Z-型表现出Z-to-E异构化，而E-型在室温下保持其构象，并且仅在高温下经历非辐射E-to-Z异构化。电子结构计算结果表明，CN-MBE分子的基态（S 0）和第一激发态（S1）的势能在烯键C → C π-键周围的扭曲构象处发生简并，导致分子的荧光猝灭.分子动力学模拟和自由能分析表明，E型分子是一种稳定的分子。
In this study, aggregation-induced emission (AIE) of a cyanostilbene derivative, called 1-cyano-1,2-bis-(4′-methylbiphenyl)ethylene (CN-MBE), was investigated using molecular simulations. The E-form of CN-MBE has been known to exhibit AIE, which is non-emissive in dilute solutions but becomes highly emissive in aggregated states, whereas its Z-form is non-emissive even in its crystalline form. In addition, upon UV light irradiation, the Z-form exhibits a Z-to-E isomerization, whereas the E-form keeps its conformation at room temperature and undergoes a nonradiative E-to-Z isomerization only at a high temperature. The results from the electronic structure calculations employed in this work showed that the potential energies of CN-MBE for the electronic ground (S0) and first excited (S1) states were degenerate at a twisted conformation around the ethylenic C═C π-bond, which led to fluorescence quenching of the molecule. Molecular dynamics simulations and free-energy analyses revealed that the E-form molecul...