Synthesis and mesomorphism study of star‐shaped carbohydrate liquid crystals containing glucosyl and glutamyl residues

Abstract

A series of novel star‐shaped carbohydrate derivative liquid crystals was synthesized with glucose as the chiral core structure. Glutamyl mesogenic moieties, l‐R‐{n‐[4‐(cholesteryloxycarbonyl)benzoyloxy]alkoxy}glutamic acid, were introduced to the five hydroxy groups of glucose by direct esterification. The chemical structures of the target liquid crystalline compounds were confirmed by element analysis and Fourier transform infrared, ¹H NMR and ¹³C NMR spectroscopy. The mesomorphic behaviour and thermal properties of target liquid crystalline compounds were investigated with differential scanning calorimetry, thermogravimetric analysis, polarizing optical microscopy, X‐ray diffraction and specific rotation. All the target compounds exhibit a cholesteric liquid crystalline phase. These compounds demonstrate a wide mesogenic region and high thermal stability. The effect of flexible spacer group length of the target compounds on the molecular structure and thermal properties is discussed.