An experimental and computational study of calamitic and bimesogenic liquid crystals incorporating an optically active [2,2]-paracyclophane
An experimental and computational study of calamitic and bimesogenic liquid crystals incorporating an optically active [2,2]-paracyclophane
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DOI：
10.1080/02678292.2018.1453559
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发表时间：
2018-03
期刊：
影响因子：
2.2
通讯作者：
R. Mandle;J. Goodby
中科院分区：
文献类型：
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作者：
R. Mandle;J. Goodby
摘要 制备了两种含有光学活性（R）-4-羟基-[2,2]-对环芳基团的液晶材料，其中一种手性基团是大体积末端单元，另一种手性基团形成三联苯状介晶单元的一部分。两种材料均表现出单向手性向列相。针对两种材料与 5CB 的混合物构建了部分相图，使我们能够推断出每种材料的节距长度和螺旋扭转功率值 (HTP)。具有“锁定”对环芳烷的材料的 HTP 值比“游离”对环芳烷高 70%，这被合理化为由于前一种材料相对于后一种材料的构象自由度降低。图解摘要
ABSTRACT Two liquid-crystalline materials containing an optically active (R)-4-hydroxy-[2,2]-paracyclophane group were prepared, one in which the chiral group is a bulky terminal unit and one in which it forms part of a terphenyl-like mesogenic unit. Both materials exhibit monotropic chiral nematic phases. Partial phase diagrams were constructed for mixtures of both materials with 5CB, allowing us to extrapolate pitch lengths and helical twisting power values (HTP) for each material. The HTP value of the material with a ‘locked’ paracyclophane is 70% higher than that of a ‘free’ paracyclophane and this is rationalised as being due to the reduction in conformational freedom of the former material relative to the later. GRAPHICAL ABSTRACT