Diastereomeric liquid crystal domains at the mesoscale

Abstract

In many technologies used to achieve separation of enantiomers, chiral selectors are designed to display differential affinity for the two enantiomers of a chiral compound. Such complexes are diastereomeric, differing in structure and free energy for the two enantiomers and enabling chiral discrimination. Here we present evidence for strong diastereomeric interaction effects at the mesoscale, manifested in chiral liquid crystal guest materials confined in a chiral, nanoporous network of semi-crystalline helical nanofilaments. The nanoporous host is itself an assembly of achiral, bent-core liquid crystal molecules that phase-separate into a conglomerate of 100 micron-scale, helical nanofilament domains that differ in structure only in the handedness of their homogeneous chirality. With the inclusion of a homochiral guest liquid crystal, these enantiomeric domains become diastereomeric, exhibiting unexpected and markedly different mesoscale structures and orientation transitions producing optical effects in which chirality has a dominant role.

Nanosegregated Chiral Materials with Self‐Assembled Hierarchical Mesophases: Effect of Thermotropic and Photoinduced Polymorphism in Rodlike Molecules

“…[4] The FFTEM images showedf ilaments tructures with ar ange of diameters larger than those of bare HNFs. [4] The FFTEM images showedf ilaments tructures with ar ange of diameters larger than those of bare HNFs.…”

“…[4] The FFTEM images showedf ilaments tructures with ar ange of diameters larger than those of bare HNFs. [4] Thus, the hierarchical chiral amplification in < HNF/SmA > is attributed to the growth of SmA layers on the HNF surfaces (Figure 3b). [4] Thus, the hierarchical chiral amplification in < HNF/SmA > is attributed to the growth of SmA layers on the HNF surfaces (Figure 3b).…”

“…Similarly,t he aforementioned nanosegregated BX phase can be represented as < HNF/N > ,w hich indicates a nanosegregated phase in which BC molecules are in the HNF phase and rodlike molecules are in the Np hase. Although an analogous mixed system of BC molecules and 8CB was previously reported, [4,5,16] detailed chiroptical observations (e.g.,C D) weren ot performed. [14] This could be attributed to at ype of chiral superstructure composed of rodlikem olecules of Np hase, which wasa ffected by the HNFs (BC molecules)a nd enhanced optical activity in the < HNF/N > phase.…”

“…[1] Chirality-related topics are of particular interest in the field of liquid-crystal (LC) science. [2][3][4][5][6][7][8] Herein, we explore an interesting chirality-related phenomenon in ab inary mixture of achiral bent-core (BC) mesogensa nd rodlikem esogens.P eculiar chiral phenomena in achiral BC mesophases have attracted significant research interest since the discovery of spontaneous chiral resolution in achiral BC molecular systems. [9,10] The mesophases found in BC molecular systems, termed "bananap hases," are different from the conventionalp hases foundi nr odlikem esogens.…”

A Dual Modulated Homochiral Helical Nanofilament Phase with Local Columnar Ordering Formed by Bent Core Liquid Crystals: Effects of Molecular Chirality

“…It was assumed that the chirality conservation only affects the handedness of the individual HNFs, either left or right handed. Clark and co‐workers recently reported that the addition of a chiral additive (or dopant) in most cases led to the formation of diastereomeric systems with equal amounts of left and right‐handed HNF nucleation sites that serve as host for the chiral additive . Not clear is the role of molecular chirality (either induced or intrinsic) on the secondary twist of HNF phases observed recently by cryo‐transmission electron microscopy (TEM) .…”