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Liquid crystal gelators with photo-responsive and AIE properties†
Materials Chemistry Frontiers ( IF 7 ) Pub Date : 2018-09-26 00:00:00 , DOI: 10.1039/c8qm00340h
Xia Yu 1, 2, 3, 4 , Hui Chen 5, 6, 7, 8, 9 , Xiang Shi 7, 10, 11, 12, 13 , Pierre-Antoine Albouy 7, 10, 11, 12, 13 , Jia Guo 1, 2, 3, 4 , Jun Hu 1, 2, 3, 4 , Min-Hui Li 1, 2, 3, 4, 5
Affiliation  

A series of new liquid crystal (LC) gelators with photo-responsive and AIE properties were synthesized by connecting cholesterol and tetraphenylethylene (TPE) to a central azobenzene moiety (trans-Cn-Chol, n = 0, 1, 3, 5), in which alkyl chains with different lengths (CH2)n were used as spacer to adjust the distance between cholesterol and azobenzene, while a fixed alkyl chain (CH2)6 was placed between azobenzene and TPE. All these trans-Cn-Chol molecules exhibit LC phase of type smectic A. Three derivatives of trans-Cn-Chol (with n = 0, 1, 3) keep their smectic A LC phases at room temperature upon cooling after at least one heating history to isotropic (Iso) phase, and present hot-crystallization (94–104 °C) upon further heating. Moreover, their thin films with LC state at room temperature can undergo photo-responsive LC–Iso phase transition under UV irradiation because of the transcis photo-isomerization of azobenzene. On the other hand, as gelators trans-Cn-Chol with long spacers, trans-C3-Chol and trans-C5-Chol, form stable low-molecular weight organogels (LMOGs) in various solvents, whereas trans-C0-Chol and trans-C1-Chol with short spacers cannot form stable LMOGs in tested solvents. Diverse supramolecular chiral structures like “sea urchins”, helical fibers, “honeycomb” and twisted ribbons were observed for both trans-C3-Chol and trans-C5-Chol gels. On account of the involvement of TPE and azobenzene moieties, these molecules present significant aggregation-induced emission (AIE) and gel-enhanced emission, and their LMOGs exhibit photo-responsive gel–sol transition. These LC molecules with gelation ability, AIE characteristics and photo-responsive properties can have potential applications as sensors and optoelectronic materials.

中文翻译:

具有光响应和AIE特性的液晶胶凝剂

通过将胆固醇和四苯基乙烯(TPE)连接至中央偶氮苯部分(反式-C n -Choln = 0、1、3、5),合成了一系列具有光响应和AIE特性的新型液晶(LC)胶凝剂,其中使用具有不同长度(CH 2n的烷基链作为间隔基来调节胆固醇与偶氮苯之间的距离,同时在偶氮苯和TPE之间放置一个固定的烷基链(CH 26。所有这些反式-C n -Chol分子均表现为近晶型A的LC相。反式-C n -Chol的三种衍生物n = 0、1、3)在经历至少一个加热至各向同性(Iso)相的过程中冷却后,将其近晶A LC相保持在室温下,并在进一步加热时呈现热结晶状态(94–104°C)。此外,由于偶氮苯的反式-顺式光致异构化,它们在室温下具有LC状态的薄膜可以在UV辐射下发生光响应性LC-Iso相变。另一方面,作为带有长间隔基的反式-C n -Chol胶凝剂,反式-C 3 -Chol反式-C 5 -Chol,形式稳定的低分子量的有机凝胶(LMOGs)在各种溶剂中,而反式-C 0 -Chol反式-C 1 -Chol短间隔物不能形成在测试溶剂中是稳定LMOGs。反式-C 3 -Chol反式-C 5 -Chol都观察到了不同的超分子手性结构,例如“海胆”,螺旋纤维,“蜂窝”和扭曲带凝胶。由于TPE和偶氮苯部分的参与,这些分子呈现出显着的聚集诱导发射(AIE)和凝胶增强发射,并且它们的LMOG表现出光响应性的凝胶-溶胶转变。这些具有胶凝能力,AIE特性和光响应特性的LC分子可以作为传感器和光电材料潜在应用。
更新日期:2018-09-26
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