Prediction of multi-stimuli responsive behavior in newly developed luminogens is an appealing yet challenging puzzle, since no concrete design strategy has been developed so far. In this article, we demonstrate a potent strategy to gain a deep understanding of the structure–property relationship to design multi-stimuli responsive mechanochromic materials. To achieve our goal, a variety of new isoindolinone core based charge transfer luminogens exhibiting aggregation-induced emission (AIE) have been prepared through C–H bond activation using a cost-effective ruthenium (Ru) metal catalyzed one-pot synthetic strategy. We have shown that slight tuning of the donor moiety is found to be highly effective in controlling molecular packing and metastable energy states in solid states, and thus, optical properties and multi-stimuli responsive behaviors. The flexibility and twisting of donor moieties afford a loosely bound ‘herringbone’ packing, enabling reversible transformation under multiple mechanical stimuli. The cyclized derivative of the donor exhibits a completely different packing mode (i.e., cross packing), and subsequently, does not give rise to mechanochromism. The Hirshfeld surface analysis from a single crystal infers that non-covalent interactions (specifically C–H⋯π and π⋯π) are extremely important to yield mechanochromism under external force. Correlating all solid-state behavior with the molecular structure, we conclude that the synergistic effect between the twisting and conformational flexibility of donor moieties along with numerous non-covalent interactions gives rise to multi-stimuli responsive behaviors. Finally, the newly designed molecules are found to be highly emissive in solution and potentially applicable in fluorescence thermometer construction, lighting up cells, acid–base sensors and rewritable devices.

中文翻译：

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开发结构-性能关系以设计固态多刺激响应材料及其在不同领域的潜在应用†

预测新开发的发光体中的多刺激响应行为是一个有吸引力但具有挑战性的难题，因为到目前为止还没有开发出具体的设计策略。在本文中，我们展示了一种有效的策略来深入了解结构-性能关系，以设计多刺激响应的机械变色材料。为了实现我们的目标，已经使用具有成本效益的钌 (Ru) 金属催化的一锅法合成策略，通过 C-H 键活化制备了各种基于异吲哚啉酮核的新型电荷转移发光体，这些发光体表现出聚集诱导发射 (AIE)。我们已经表明，发现供体部分的轻微调整在控制分子堆积和固态亚稳态能态方面非常有效，因此，光学特性和多刺激响应行为。供体部分的灵活性和扭曲提供了松散结合的“人字形”包装，从而在多种机械刺激下实现可逆转化。供体的环化衍生物表现出完全不同的堆积方式（即，交叉堆积），因此不会产生机械变色。来自单晶的 Hirshfeld 表面分析推断非共价相互作用（特别是 C-H⋯π 和 π⋯π）对于在外力下产生机械变色极为重要。将所有固态行为与分子结构相关联，我们得出结论，供体部分的扭曲和构象灵活性以及许多非共价相互作用之间的协同效应导致了多刺激响应行为。最后，发现新设计的分子在溶液中具有高发射率，并可能适用于荧光温度计结构、照明电池、酸碱传感器和可重写设备。