Chiral symmetry breaking in soft matter is a hot topic of current research. Recently, such a phenomenon was found in a fluidic phase showing orientational order of molecules-the nematic phase; although built of achiral molecules, the phase can exhibit structural chirality-average molecular direction follows a short-pitch helix. Here, we report a series of achiral asymmetric dimers with an odd number of atoms in the spacer, which form twisted structures in nematic as well as in lamellar phases. The tight pitch heliconical nematic (N_TB) phase and heliconical tilted smectic C (SmC_TB) phase are formed. The formation of a variety of helical structures is accompanied by a gradual freezing of molecular rotation. In the lowest temperature smectic phase, HexI, the twist is expressed through the formation of hierarchical structure: nanoscale helices and mesoscopic helical filaments. The short-pitch helical structure in the smectic phases is confirmed by resonant X-ray measurements.

中文翻译：

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非手性分子形成的螺旋近晶相。

软物质中的手性对称性断裂是当前研究的热点。近来，在显示分子取向顺序的流体相-向列相中发现了这种现象。尽管由非手性分子构成，但该相可表现出结构性手性平均分子方向遵循短节距螺旋。在这里，我们报道了一系列的非手性不对称二聚体，在间隔基中具有奇数个原子，它们在向列相以及层状相中形成扭曲的结构。紧密螺距螺旋向列相（N _TB）和倾斜斜向近晶C（SmC _TB）相形成。各种螺旋结构的形成伴随着分子旋转的逐渐冻结。在温度最低的近晶相HexI中，扭曲是通过以下分层结构的形成来表达的：纳米级螺旋和介观螺旋丝。近晶相中的短螺距螺旋结构通过共振X射线测量得到证实。