“Tuning fork”-shaped mesogens: large hysteresis in the interdigitated layer structure in the liquid crystal phases

Abstract

Compounds 1, N,N-bis{4-[4-(4-alkoxybenzoyloxy)benzyloxy]benzoyl}alkylamines, were designed and synthesized as “tuning fork”-shaped molecules, and their properties were investigated by polarized light microscopy and differential scanning calorimetry, and the layer distances were measured by X-ray diffraction. The observed smectic A liquid crystal phases indicated the existence of large hysteresis in XRD. The multiple broad peaks of the layer distances originated in the plural extent of interdigitation of the alkyl chains between the layers, and the layer distances strongly depended on the hysteresis. Further, the chiral and racemic liquid crystalline compounds, (R)-1k and rac-1k, showed a clear difference in the interlayer interdigitations in their mesophases.