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H-Shape mesogenic dimers – the spacer parity effect

机译：H形介晶二聚体–间隔位平价效应

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It was found that for H-shape dimers, the parity of the number of atoms in the spacer linking the mesogenic cores has important influence on the mesogenic properties only for the molecules with weak mesogenic core anisotropy. In the case of stronger core anisotropy, the parallel arrangement of mesogenic units is induced regardless of the spacer parity. As a result, phase transition temperatures and layer spacing are only weakly affected by spacer parity. By studying the properties of six new homologue series it was found that for H-shape dimers the orthogonal smectic (SmA) is strongly disfavoured: most compounds form a tilted smectic (SmC) phase, which is related to hindrances in molecular rotation for molecules with large breath to length ratio. For dimers with very long spacer, and thus decoupled mesogenic units, the smectic phase is replaced by a nematic phase, and for stiff polycatenar molecules with very short spacers the cubic phase can appear.
机译：发现对于H型二聚体，连接介晶核的间隔基中原子数的奇偶性仅对介晶核各向异性弱的分子对介晶性能具有重要影响。在核心各向异性较强的情况下，无论间隔子的奇偶性如何，均会引起介晶单元的平行排列。结果，间隔物的奇偶性仅对相变温度和层间距产生微弱的影响。通过研究六个新的同源序列的性质，发现对于H型二聚体，强烈不赞成使用正交近晶（SmA）相：大多数化合物形成倾斜近晶（SmC）相，这与分子结构受阻的分子旋转有关。呼吸长度比大。对于间隔物非常长的二聚体，从而使介晶单元解耦，近晶相被向列相取代;对于间隔物非常短的硬聚类别分子，立方相会出现。

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