Effect of Central Longitudinal Dipole Interactions on Chiral Liquid-Crystal Phases

Abstract

Monte Carlo simulations of chiral liquid-crystals, represented by a simple coarse-grained chiral Gay–Berne model, were performed to investigate the effect of central longitudinal dipole interactions on phase behavior. A systematic analysis of the structural properties and phase behavior of both achiral and chiral systems, with dipole interactions, reveals differing effects; strong dipole interactions enhance the formation of layered structures; however, chiral interactions may prevent the formation of such phases under certain conditions. We also observed a short-ranged smectic structure within the cholesteric phases with strong dipole interactions. This constitutes possible evidence of presmectic ordering and/or the existence of chiral line liquid phases, which have previously been observed in X-ray experiments to occur between the smectic twisted grain boundary and cholesteric phases. These results provide a systematic understanding of how the phase behavior of chiral liquid-crystals changes when alterations are made to the strength of dipole interactions.

Pre-Smectic Ordering and the Unwinding Helix in Monte Carlo Simulations of Cholesteric Liquid-Crystals

“…Here, we observe an apparent increase in smectic order occurring concurrently with an unwinding of the cholesteric helix. Prior simulation work had shown a small increase in smectic ordering before the cholesteric to smectic phase transition, 37 but it was unclear if this occurred concurrently with the unwinding of the cholesteric helix. In the section that follows, we will investigate this question in more detail.…”

“…Simulating electrostatic chirality may be achieved in several ways: by creating bespoke coarse-grained models, which are suitable for complex molecules; ,, by using computationally efficient simple lattice − and off-lattice − models; by modification of existing achiral potentials, such as the chiral Gay-Berne potential; , and by all-atom models, although the latter is by far the most computationally expensive. There are also approaches that include the combination of a hard repulsive core with chiral electrostatics .…”

Visualizing the helical stacking of octahedral metallomesogens with a chiral core

“…In addition to the molecular structure, we further consider the effect of dipolar interactions in the helix formation. 32,33 The core structure of Ru-C8, [Ru(acacC 2 Ph) 3 ], was deduced to have a dipole moment of ca. 0.92 Debye along the C 2 axis based on the DFT calculation (Fig.…”