摘要：SummaryThe 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 onE-Zisomerization (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.Graphical AbstractDisplay OmittedHighlights•A new aggregation-induced emission building block•A novel AIE mechanism with spectral measurements and theoretical calculations•Available starting materials resulting in convenient synthesis and modification•A stable exocyclic C=N double bond in heterocyclesTheoretical Methods in Chemical Physics; Molecular Electronic Structure; Chemical Synthesis
