The study of shrinkage behavior in supramolecular soft materials via the variation of shape and volume can contribute to a better understanding of and the mimicking of motions that occur in diverse organisms. The fabrication of self-shrinkable supramolecular gels is of great significance in actively moving systems but is still a big challenge. Aggregation-induced emission (AIE) has been an extremely hot topic and is believed to have significantly stimulated the development of luminescent supramolecular materials. Its realization in self-shrinkable materials can both provoke academic interest and widen the number of innovative applications for actively moving systems. Herein, we proposed a novel molecular design strategy to give self-shrinkable AIE supramolecular gels via the use of three benzophenone salicylaldehyde hydrazine derivatives substituted with different length alkyl chains. These gelator molecules prefer to adopt a twisted conformation in the monomolecular and assembled state which is beneficial to their AIE behaviors. The gels of these molecules exhibit distinct phase behaviors where those with longer alkyl chains result in the self-shrinkage of the gel. We consider that this is due to the enhancement of the mobility of the packing layers and thus a shorter inter-layer distance that leads to tighter stacking. The self-shrinkage process was concomitant with a variation in the morphology from a macroporous honeycomb structure to a more aligned and regular nanofibrous structure with an accompanying emission enhancement.

中文翻译：

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基于二苯甲酮水杨醛肼衍生物的可自收缩AIE超分子凝胶的简便制备

通过形状和体积的变化研究超分子软材料的收缩行为，可以有助于更好地理解和模仿各种生物体中发生的运动。自收缩超分子凝胶的制备在主动移动系统中具有重要意义，但仍然是一个巨大的挑战。聚集诱导发射（AIE）一直是一个非常热门的话题，并且据信已经极大地刺激了发光超分子材料的发展。它在可自动收缩的材料中的实现既引起了学术兴趣，也扩大了主动移动系统的创新应用数量。在本文中，我们提出了一种新颖的分子设计策略，可通过以下方式产生可自收缩的AIE超分子凝胶：使用三种二苯甲酮水杨醛肼衍生物取代不同长度的烷基链。这些胶凝剂分子倾向于在单分子和组装状态下采用扭曲构象，这有利于其AIE行为。这些分子的凝胶表现出明显的相行为，其中具有较长烷基链的分子导致凝胶自收缩。我们认为这是由于填料层迁移率的提高，从而缩短了层间距离，从而导致了更紧密的堆叠。自收缩过程伴随着形态的变化，从大孔蜂窝状结构到更排列和规则的纳米纤维结构，并伴有发射增强。