Abstract.

We discuss the symmetry properties as well as the macroscopic behavior of the cubic liquid crystal phases showing large chiral domains of either hand in some non-chiral compounds reported recently in the group of Tschierske. These phases are tricontinuous. While they have O or I432 symmetry in each chiral domain, the overall symmetry is \( I m \bar{3} m\) as there is no net chirality for compounds composed of non-chiral molecules. It turns out that a rather similar type of phase has also been reported for triblock copolymers. Here we analyze in detail the macroscopic static and dynamic behavior of such phases and we predict, among other results, that they show the analog of static and dissipative Lehmann-type effects in their chiral domains. A description of a cubic liquid crystalline phase of T_h symmetry, which has not yet been found experimentally, is also included. Suggestions for experiments are outlined to identify such a phase. In addition, we discuss tetragonal liquid crystalline phases of D_4h and D₄ (I422) symmetry as they have been reported last year experimentally in connection to the Q phase.

Graphical abstract

中文翻译：

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由非手性分子组成的立方和四方液晶相：手性和宏观性质。

摘要。

我们讨论了对称的性质以及立方液晶相的宏观行为，这些液晶相在Tschierske组中报告的一些非手性化合物中显示出两只手的较大手性域。这些阶段是三连续的。尽管它们在每个手性域中具有O或I 432对称性，但总体对称性为\（I m \ bar {3} m \）因为由非手性分子组成的化合物没有净手性。事实证明，对于三嵌段共聚物也已经报道了相当相似的相。在这里，我们详细分析了此类相的宏观静态和动态行为，并且除其他结果外，我们预测它们在它们的手性域中显示出静态和耗散Lehmann型效应的类似物。还包括对T _h对称的立方液晶相的描述，该描述尚未通过实验找到。概述了用于确定这一阶段的实验建议。此外，我们讨论了D _4h和D ₄（I422）对称性的四方液晶相，因为它们去年在实验中已被报告与Q有关。 相。

图形概要