Subtle modification of molecular structure can play a crucial role in determining photophysical properties and stimuli-responsive behavior. Herein, four aggregation-induced emission (AIE)-active tetraphenylethylene-based positional isomers S1, S2, S3 and S4 have been designed and synthesized. S2 and S4 exhibit higher fluorescence quantum yield (Φ_FL) as compared to S1 and S3, respectively, which was due to the positional isomerism. In addition, all four isomers exhibit reversible mechanofluorochromic (MFC) behavior with mechanical-induced emission enhancement (MIEE), which was studied using powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). S1 and S2 display better MFC activities, compared with S3 and S4, due to opened phenylimidazole presenting a more twisted conformation. Moreover, they can detect picric acid (PA) in a highly selective and sensitive manner in aqueous media, due to the excellent proton-binding property of the imidazole group, which was verified by ¹H NMR spectra and supported by theoretical calculations. Overall, tetraphenylethylene containing arylimidazole derivatives described herein will efficiently expand the development of design principles to supply diverse multifunctional tools for material science and material engineering.

分子结构的细微修饰可以在确定光物理性质和刺激响应行为中发挥关键作用。在此，已经设计并合成了四种聚集诱导发射（AIE）活性的基于四苯基乙烯的位置异构体S1，S2，S3和S4。S2和S4显示出更高的荧光量子产率（Φ _FL相比）S1和S3分别是由于位置异构所致。此外，所有四种异构体均表现出可逆的机械荧光致变色（MFC）行为和机械诱导的发射增强（MIEE），已使用粉末X射线衍射（PXRD），差示扫描量热法（DSC）和扫描电子显微镜（SEM）对其进行了研究。与S3和S4相比，S1和S2显示出更好的MFC活性，这是因为打开的苯基咪唑呈现出更多的扭曲构象。此外，由于咪唑基团具有出色的质子结合性能，因此可以在水介质中以高选择性和灵敏的方式检测苦味酸（PA），这一点已通过¹ H验证。NMR光谱并得到理论计算的支持。总体而言，本文所述的含四苯基乙烯的芳基咪唑衍生物将有效地扩展设计原理的发展，以提供用于材料科学和材料工程的各种多功能工具。