Synchronization of conformational chirality in mixtures of achiral bent-core molecules.

Abstract

Molecular conformational chirality has been proposed as a possible driving force for chiral symmetry breaking in fluids composed of achiral molecules, with deracemization being initiated by segregation of enantiomeric conformers. Using binary mixtures of liquid crystals made of achiral bent-core molecules, we now show that enantiomeric excess depends on chirality synchronization between conformers. This is manifested by the formation of two types of lamellar dark mesophases viz. the dark enantiomeric phase characterized by only one sense of chirality and the dark conglomerate phase composed of homochiral domains with opposite handedness. The severity of layer deformation in the dark phases, resulting from the frustration caused by the packing of chiral conformers within the layers is also found to depend on concentration. Electro-optic and dielectric responses reflect the layer deformation and the compactness of the sponge like layer structure and hence the efficiency of conformer packing. The severity of layer deformation has been monitored by visualizing the layer profiles using SEM. This type of study can contribute to the understanding of selective homochirality at the molecular level in achiral systems.