Shape-Directed Self-Assembly into Columnar Phases: Beyond the Discotic Paradigm

Abstract

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