The development of aggregation-induced emission (AIE) building block and deciphering its luminescence mechanism are of great significance. Here a feasible strategy for the construction of AIE unit based on E-Z isomerization (EZI) of exocyclic C=N double bond is proposed. Taking [1,2,4]thiadiazole[4,3-a]pyridine (TZP) derivative as an example, its aryl-substituted derivative (TZPP) shows obvious AIE character. The analysis of spectral data and theoretical calculations indicates that fast structural relaxation of TZPP in the emissive state plays a key role in a low fluorescence quantum yield in dilute solution, which should be caused by the small energy gap between locally excited (LE) state and twisted intramolecular charge transfer state. When in solid state, the bright emission with LE state characteristic reappears due to the large shift barrier of geometry transformation. As a potential building block for AIEgens with special heterocyclic structure, these findings would open up opportunities for developing various functional materials.

聚集诱导发射（AIE）构件的发展及其发光机理的研究具有重要意义。提出了基于环外C = N双键的E - Z异构化（EZI）构建AIE单元的可行策略。服用[1,2,4]噻二唑[4,3- a以]吡啶（TZP）衍生物为例，其芳基取代的衍生物（TZPP）具有明显的AIE特性。光谱数据分析和理论计算表明，在稀溶液中低发射荧光量子产率中，发射态的TZPP的快速结构弛豫起着关键作用，这可能是由于局部激发（LE）态与分子之间的小能隙引起的。扭曲的分子内电荷转移状态。当处于固态时，由于几何转换的大位移势垒，具有LE状态特征的明亮发射再次出现。作为具有特殊杂环结构的AIEgens的潜在构建基，这些发现将为开发各种功能材料开辟机会。