Shape-directed self-assembly into columnar phases: beyond the discotic paradigm

Abstract

The study of columnar liquid crystals (LCs) has historically been dominated by discotic molecules, where planar disc-shaped molecules stack into one-dimensional wires. However, there exists a plethora of non-discotic architectures, such as calamitic, phasmidic, conic, and bent-core, which can defy the classical geometric expectations to form a columnar phase with simple structural modifications. Herein, supramolecular mechanisms such as nanophase segregation, geometric frustration, and supramolecular aggregation were examined, which nudge these non-conventional tectons to achieve columnar self-assembly. Although the structural diversity of mesogens is extensive, the fundamental forces governing the columnar order can be established as interfacial curvature and spatial volumetric mismatch. This review offers a targeted look at examples of non-conventional liquid crystals to establish the ability of minor functional modifications to generate significant shape disparity, which drives self-assembly into distinct columnar patterns.