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首页> 美国卫生研究院文献>International Journal of Molecular Sciences >Review of Crystalline Structures of Some Selected Homologous Series of Rod-Like Molecules Capable of Forming Liquid Crystalline Phases
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Review of Crystalline Structures of Some Selected Homologous Series of Rod-Like Molecules Capable of Forming Liquid Crystalline Phases

机译：几种能够形成液晶相的棒状分子同源序列的晶体结构研究

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摘要

The crystal structures of four homologous series of rod-like molecules are reviewed, two of which form hydrogen bonds and two with a symmetric chemical constitution. Many of the compounds investigated turn into liquid crystalline phases upon temperature increase. It is of valuable interest to know possible conformations and possible packing arrangements as prerequisites to model liquid crystalline structures. The hydrogen bonds of homologous series of pure 4-(ω-hydroxyalkyloxy)-4′-hydroxybiphenyl (HnHBP, n the alkyloxy tail length) are realized through head to tail arrangements of the hydroxyl groups and crystallize except one compound in chiral space groups without the molecules containing any asymmetric carbon. The hydrogen bonds of the homologous series of 4-substituted benzoic acids with various lengths of the tail provide dimers through strong polar bonding of adjacent carboxyl groups and thus provide the stiff part of a mesogenic unit prerequisite for liquid crystalline phases. The homologous series of dialkanoyloxybiphenyls (BP-n, n = 1, 19), of which nine compounds could be crystallized, show liquid crystalline behavior for longer alkane chain lengths, despite the high mobility of the alkane chain ends already detectable in the crystal phase. A single molecule, half a molecule or two half molecules form the asymmetric unit in a centrosymmetric space group. The homologous series of 1,4-terephthalidene-bis-N-(4′-n-alkylaniline) (TBAA-n) exhibit a large variety of packing arrangements in the crystalline state, with or without relying on the symmetry center within the molecules.
机译：审查了四个同源系列的棒状分子的晶体结构，其中两个形成氢键，两个具有对称的化学组成。随着温度的升高，许多研究的化合物变成液晶相。知道可能的构象和可能的排列方式是对液晶结构建模的先决条件，这是非常有价值的兴趣。通过羟基的头尾排列实现纯4-（ω-羟基烷氧基）-4'-羟基联苯（HnHBP，n为烷氧基尾长）的同源系列的氢键，并结晶，除了手性空间基团中不具有含有任何不对称碳的分子。具有不同尾巴长度的4-取代苯甲酸同源系列的氢键通过相邻羧基的强极性键提供二聚体，因此提供液晶相必备的介晶单元的刚性部分。尽管可以在结晶相中检测到烷烃链端的高迁移率，但其中的九种化合物可以结晶的二烷氧基酰氧基联苯的同系系列（BP-n，n = 1、19）。 。一个单一分子，一个半分子或两个半分子形成一个中心对称空间群中的不对称单元。 1,4-对苯二亚甲基-双-N-（4'-n-烷基苯胺）（TBAA-n）的同源系列在晶体状态下具有多种堆积排列，无论是否依赖于分子内的对称中心。

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