Chiral domain formation and spontaneous de-racemization in the Dark Conglomerate phase of a bent-core liquid crystal

Abstract

One of the more recent additions to the wealth of thermotropic liquid crystals are the various phases of bent-core molecules. In particular the Dark Conglomerate phase is still quite intriguing, as it displays the relatively uncommon phenomena of spontaneous de-racemization, the formation of two types of chiral domains in the absence of overall chirality of the constituent molecules or the macroscopic phase. This domain formation was investigated in detail with respect to cooling rate and applied electric fields. It was found that any effects of domain coarsening or aging are practically absent and that only the cooling rate influences the domain sizes and thus their number density. The presence of an electric field during the domain formation results in a modification from shape-anisotropic domains with an aspect ratio of length to width of approximately L/W ≈ 3 at zero field, to shape isotropic domains with an aspect ratio of about L/W ≈ 1 at non-zero field. The overall chirality of the investigated materials remains unaltered in all cases.