The halogen atoms have been exploited for designing highly efficient aggregation-induced emission (AIE) materials in recent years, whereas the development of halogenated AIEgen has been greatly limited by the unclear inherent mechanism. In this paper, a series of 1,1,2,2-tetrakis (4-(phenyl ethynyl) phenyl) ethene (TPPE) derivatives with bromine (Br) substituents in different positions were synthesized and their unique photophysical behaviors based on the anti-heavy atom effect were investigated. The brominated TPPE derivatives possessed higher fluorescence quantum yield () than that of TPPE, resulting from the formation of intermolecular Br-based bonds. Single crystal analysis and theoretical calculations revealed that changing the positions of the Br substituents could induce the formation of different intermolecular interactions. The Br-based bonds efficiently restricted the intermolecular motion, in which the Br⋯Br bond made a decisive factor in determining the highly efficient fluorescence. TPPE derivatives displayed obvious mechanofluorochromic (MFC) properties. PXRD and SEM results demonstrated that the crystal-to-amorphous transition attributed to the reversibility of MFC properties. This work provides a straightforward and practical method to achieve highly efficient AIE-active materials with higher contrast MFC properties via introducing the halogen atoms.

中文翻译：

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四苯乙烯基发光体的溴取代基位置通过卤素键对增强 AIE 和可逆机械荧光变色性能的影响

近年来，卤素原子被用来设计高效的聚集诱导发射（AIE）材料，而卤代AIEgen的发展却因不清楚的内在机制而受到极大限制。本文合成了一系列在不同位置带有溴（Br）取代基的1,1,2,2-四（4-（苯基乙炔基）苯基）乙烯（TPPE）衍生物，并基于反光性能研究了它们独特的光物理行为。 -研究了重原子效应。溴化 TPPE 衍生物由于分子间 Br 基键的形成而具有比 TPPE 更高的荧光量子产率 ()。单晶分析和理论计算表明，改变Br取代基的位置可以诱导不同分子间相互作用的形成。 Br基键有效地限制了分子间运动，其中Br⋯Br键是决定高效荧光的决定性因素。 TPPE衍生物表现出明显的机械荧光变色（MFC）特性。 PXRD 和 SEM 结果表明，晶体到非晶态的转变归因于 MFC 性能的可逆性。这项工作提供了一种简单实用的方法，通过引入卤素原子来实现具有更高对比度 MFC 性能的高效 AIE 活性材料。