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Polymorphism manipulating topo-photochemical reactions, photoactuation, and the mechanofluorochromism of benzimidazoleylaryl acrylonitriles
Journal of Materials Chemistry C ( IF 5.7 ) Pub Date : 2023-12-01 , DOI: 10.1039/d3tc03586g
Cheng Liu 1 , Jingbo Sun 1 , Chao Chen 1 , Kaiqi Ye 1 , Haoran Wang 1 , Xiqiao Yang 1 , Yuan Yue 1 , Ran Lu 1
Affiliation  

Polymorphism arising from different conformations or packing arrangements in crystal lattices would manipulate physical properties, including morphology, electrical conductivity, emission, and nonlinear optical properties. However, the photochemistry tuned by polymorphism is seldom reported. In this work, photochemical reactive isomers of (E)-2-(1H-benzo[d]imidazol-2-yl)-3-(4-fluorophenyl)acrylonitrile (E-CN-BIFPh) and (Z)-3-(1H-benzo[d]imidazol-2-yl)-2-(4-fluorophenyl)acrylonitrile (Z-BIFPh-CN) in which a cyano group is located on different positions in conjugated skeletons were synthesized. Interestingly, E-CN-BIFPh crystallized into sheet-like structures emitting orange-red fluorescence (OR-phase) and block-like structures showing green fluorescence (G-phase). Besides, cuboid-like crystals with green fluorescence (G-phase) and needle-like crystals emitting blue light (B-phase) were formed from Z-BIFPh-CN. It is interesting that [2+2] cycloaddition took place only in the OR-phase crystal of E-CN-BIFPh and the B-phase crystal of Z-BIFPh-CN, which powered the molecular crystals to exhibit obvious photoactuation. In the case of the G-phase crystals of E-CN-BIFPh and Z-BIFPh-CN, the geometric parameters for “olefin pair” deviated from Schmidt's criteria, and hence, no photodimerization occurred. Notably, the OR-phase crystal of E-CN-BIFPh exhibited high-contrast mechanofluorochromism (MFC) with a red-shift of 115 nm in emission. The phase transition of the G-phase crystals of Z-BIFPh-CN upon heating at 105 °C led to a change in the emission color from green to blue, showing thermochromism. Such polymorphism crystallization-controlled multi-stimuli-responsive molecular crystals might be employed as elements in artificial muscles, smart microrobots, wearable systems and sensors.

中文翻译:


操纵苯并咪唑芳基丙烯腈的拓扑光化学反应、光致动和机械荧光显色的多晶型



晶格中不同构象或堆积排列产生的多态性将操纵物理性质,包括形态、电导率、发射和非线性光学性质。然而,通过多态性调节光化学的报道却很少。在这项工作中,(E)-2-(1H-苯并[d]咪唑-2-基)-3-(4-氟苯基)丙烯腈(E-CN-BIFPh)和(Z)-3-的光化学反应异构体合成了氰基位于共轭骨架中不同位置的(1H-苯并[d]咪唑-2-基)-2-(4-氟苯基)丙烯腈(Z-BIFPh-CN)。有趣的是,E-CN-BIFPh 结晶成发射橙红色荧光的片状结构(OR 相)和显示绿色荧光的块状结构(G 相)。此外,Z-BIFPh-CN还形成了具有绿色荧光的长方体晶体(G相)和发射蓝光的针状晶体(B相)。有趣的是,[2+2]环加成仅发生在E-CN-BIFPh的OR相晶体和Z-BIFPh-CN的B相晶体中,这使得分子晶体表现出明显的光致驱动作用。对于E-CN-BIFPh和Z-BIFPh-CN的G相晶体,“烯烃对”的几何参数偏离施密特标准,因此没有发生光二聚化。值得注意的是,E-CN-BIFPh 的 OR 相晶体表现出高对比度机械荧光变色(MFC),发射红移为 115 nm。 Z-BIFPh-CN 的 G 相晶体在 105 °C 加热时发生相变,导致发射颜色从绿色变为蓝色,表现出热致变色现象。 这种多晶型结晶控制的多刺激响应分子晶体可以用作人造肌肉、智能微型机器人、可穿戴系统和传感器中的元件。
更新日期:2023-12-01
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