Hu Ming, Ye Feng-Ying, Yu Wei, Sheng Kang, Wang Weizhou, Zheng Yan-Song
Key Laboratory of Material Chemistry for Energy Conversion and Storage, Ministry of Education, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China.
College of Chemistry and Chemical Engineering, Henan Key Laboratory of Function-Oriented Porous Materials, Luoyang Normal University, Luoyang, 471934, China.
Chemistry. 2023 Dec 6;29(68):e202302567. doi: 10.1002/chem.202302567. Epub 2023 Oct 20.
Aggregation-induced emission (AIE) and aggregation-caused quenching (ACQ) are two classes of opposite luminescence phenomena. It is almost impossible to show both AIE and ACQ effect simultaneously by the same molecule. However, here we report that a simple TPE derivative TAP-TPE grows into both AIE crystals and ACQ ones. It is found that equatorial, contact distance-longer and weak ArH-π interactions exist in AIE crystals while vertical, contact distance-shorter and strong ArH-π interactions appear in ACQ crystals. Theoretical calculation of electron density on the interaction atoms unveils that ACQ crystals have much larger change in electron density than AIE ones, suggesting that the intermolecular electron transfer aroused by the strong ArH-π hydrogen bonds leads to ACQ phenomenon. This result provides a new insight into the emission mechanism in aggregation state. Interestingly, due to the ArH-pi interactions difference, only one of five kinds of crystals shows rapid photochromism, and can act as multimode anti-counterfeiting materials. Very exceptionally, for the first time we find that the photochromic micrometric rod-like crystal even makes forward rolling movement as it repeatedly bends and straightens by responding to on and off of the ultraviolet light irradiation, displaying potential for photo-actuator and light-driven micro-vehicle.
聚集诱导发光（AIE）和聚集导致猝灭（ACQ）是两类相反的发光现象。同一分子几乎不可能同时表现出AIE和ACQ效应。然而，在此我们报道一种简单的TPE衍生物TAP-TPE能形成AIE晶体和ACQ晶体。研究发现，AIE晶体中存在赤道面、接触距离更长且较弱的ArH-π相互作用，而ACQ晶体中则出现垂直、接触距离较短且较强的ArH-π相互作用。对相互作用原子上电子密度的理论计算表明，ACQ晶体的电子密度变化比AIE晶体大得多，这表明由强ArH-π氢键引起的分子间电子转移导致了ACQ现象。这一结果为聚集态下的发光机制提供了新的见解。有趣的是，由于ArH-π相互作用的差异，五种晶体中只有一种表现出快速光致变色，并且可以用作多模式防伪材料。非常特别的是，我们首次发现光致变色微米级棒状晶体在反复响应紫外光照射的弯曲和伸直过程中甚至会向前滚动，展现出作为光驱动器和光驱动微型车辆的潜力。
