Aggregation-caused quenching (ACQ) and aggregation-induced emission (AIE) are dictated by the molecular aggregation which in turn is decided by the chemical features present in a molecule. The photophysical properties of bis(pyrenyl)-di-imines were investigated in solution as well as the solid state. It was observed that the light-emitting properties are dependent on the type of spacer group present in the compound. The presence of an alkylene spacer [ethylene (L3), butylene (L4), and hexylene (L5)] in bis(pyrenyl)-di-imines showed AIE at higher concentrations as well as in the solid state whereas the presence of a phenylene (L1) spacer and the absence of any alkyl/aryl spacer (L2) in the compound have resulted in ACQ in the solid state. Crystal structure analysis of L1 has explained its non-emissive nature in the solid state, while the AIE in the compounds, L3–L5, where flexible alkylene spacers are present, provided an idea about the solid-state arrangement of the molecules.

中文翻译：

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通过调节间隔基团的化学功能来控制双（芘基）-二亚胺的发光特性

聚集引起的猝灭 (ACQ) 和聚集引起的发射 (AIE) 由分子聚集决定，而分子聚集又由分子中存在的化学特征决定。在溶液和固态中研究了双（芘基）-二亚胺的光物理性质。据观察，发光特性取决于化合物中存在的间隔基团的类型。双（芘基）-二亚胺中亚烷基间隔基 [乙烯 ( L3 )、丁烯 ( L4 ) 和己烯( L5 )] 的存在在较高浓度和固态下显示出 AIE，而亚苯基的存在( L1 ) 间隔区和不存在任何烷基/芳基间隔区 ( L2) 在化合物中产生了固态的 ACQ。L1 的晶体结构分析解释了它在固态下的非发射性质，而化合物中的 AIE，L3-L5，其中存在柔性亚烷基间隔基，提供了关于分子固态排列的想法。