Photomechanical dynamic molecular crystals provide a platform for the transition from photo energy to mechanical motions. However, the development of modulating multiple photomechanical modes through crystal size tuning is in the preliminary stage. In this study, the shape-dependent photomechanical motions of molecular crystals based on a cyclohexyl-substituted cyanostilbene derivative (CSHe) are investigated. A series of crystals with different shapes, including ribbon, needle, and plate, are prepared from the same molecule by modulating the crystal culture conditions. These crystals exhibit excellent photo-induced mechanical behaviors caused by the efficient lattice deformation from [2 + 2] cycloaddition photoreaction in the crystal. With the variety of crystal size and shape of crystals, the crystal photomechanical motions are dominantly varied from the twisting of the ribbon to the disintegration of bulk crystals. Our work broadens the insight for developing the photoresponsive modes of dynamic stilbene molecular crystals.

中文翻译：

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氰芪基分子晶体的形状相关光机械运动

光机械动态分子晶体为从光能到机械运动的转变提供了一个平台。然而，通过晶体尺寸调节来调制多种光机械模式的开发还处于初级阶段。在这项研究中，研究了基于环己基取代的氰基芪衍生物 (CSHe) 的分子晶体的形状依赖性光机械运动。通过调节晶体培养条件，由同一分子制备一系列不同形状的晶体，包括带状、针状和板状。这些晶体表现出优异的光致机械行为，这是由晶体中 [2 + 2] 环加成光反应产生的有效晶格变形引起的。随着晶体大小和晶体形状的变化，晶体光机械运动主要从带的扭曲到块状晶体的解体变化。我们的工作拓宽了开发动态二苯乙烯分子晶体的光响应模式的视野。