Supermolecular Bent Configuration Composed of Achiral Flexible Liquid Crystal Trimers Exhibiting Chiral Domains with Opposite Handedness

Abstract

Chirality's effects on physical properties of materials and how chirality arises have persisted as attractive issues in chemistry. We prepared a homologous series of achiral liquid crystal trimers in which three phenylpyrimidine units are connected via flexible heptamethylene spacers. An equimolecular mixture of a trimer with a nematic (N) phase and that with smectic A (SmA), smectic C (SmC), and smectic B phases was found to exhibit an N phase, a SmC phase, and a B4 phase composed of chiral domains with opposite handedness. The chiral characteristics of the B4 phase were confirmed by uncrossing the polarizers in opposite directions. XRD measurements reveal that both SmC and B4 phases have an interdigitated layer structure. That molecular interdigitation might form a supermolecular bent configuration that can produce saddle splay curvature to drive the B4 phase.

The stabilisation of the Nxphase in mixtures

“…We note too that quite complex packing behaviour has been observed in a number of flexibly linked smectic systems. 38,39 It has been considered that in these dimeric systems the molecules pack in an antiparallel arrangement through overlapping associations of their cyanobiphenyl units, a sketched representation of such a molecular assembly is shown in Fig. 9.…”

Chiral conglomerates observed for a binary mixture of a nematic liquid crystal trimer and 6OCB

“…44 This report describes that binary mixtures of an achiral nematic liquid crystal trimer and 4'-hexyloxy-4-cyanobiphenyl (6OCB) exhibit a DC phase. 44 This report describes that binary mixtures of an achiral nematic liquid crystal trimer and 4'-hexyloxy-4-cyanobiphenyl (6OCB) exhibit a DC phase.…”

Dynamic control and functionalization of supramolecular chirality

“…刘鸣华课题组 [46] 成为液晶领域的热点之一 [53] . 李全课题组 [54] 手性液晶材料也可以完全由非手性分子通过分 子间相互作用组装而成 [55] . 非手性的弓形分子(如香 蕉形分子 [56] 、曲棍球杆形分子 [57] [58]…”