Nanostructural polymorphism in the low-birefringence chiral phase of an achiral bent-shaped dimer

TL;DR

This study reveals polymorphism in a low-birefringence chiral phase of an achiral liquid crystal, showing interconnected nano-architectures and discovering a novel nanotube-like structure influenced by solvent conditions.

Contribution

It demonstrates the connection between B4 and DC phases in a single compound and reports a new nanotube-like structure in achiral liquid crystals.

Findings

B4 and DC phases are connected via nano-architectures.

A novel nanotube-like structure was discovered.

Polymorphism manifests in low-birefringence, chiral phases.

Abstract

Polymorphism, the phenomenon that a species can exist in many discrete forms, is common in nature, such as hair colors in an animal species, flower colors in a tree species, and blood types in humans, etc. In materials science, it refers to a solid that can exist in multiple forms with different crystalline structures. In the liquid crystals field, however, polymorphism is hard to find because a discontinuous structural variation is basically impossible because of their fluid or partially fluid nature. Herein we show that the B4 and DC phases that for many years have been classified as distinctive phases are connected, in terms of their nano-architectures, based on the study of a single compound, a flexible bent-shaped dimer. The surrounding solvent is the key to assisting the dimeric molecules in morphing and adopting different supramolecular structures at the mesoscale. Furthermore, we accidentally find a novel nanotube-like structure that has not yet been reported in view of the B4/DC phases. Together with the known sponge (DC) and the helical filament (B4) structures, they are just some of the manifestations of the polymorphism in a class of low-birefringence, chiral phase from achiral liquid crystals.