Synthesis and liquid crystalline properties of a novel series of dimesogenic compounds containing chiral(-) menthyl groups

摘要

A novel series of symmetric dimesogenic compounds which containing Schiff's base moieties and chiral menthyl groups were designed and synthesized. The target dimesogenic compounds were obtained by the reaction of corresponding (-) menthyl-containing carboxylic acids and 1, 4-bis(aminophenyl-1-oxy)butane, and the outer spacers between Schiff's base moieties and chiral menthyl groups were 2, 4, 6 and 8 methylenes. The chemical structures of this series of dimesogenic compounds and intermediates were characterized by FT-IR, ¹H-NMR. The liquid crystalline properties of dimesogenic compounds were characterized by hot-stage coupled polarizing microscopy and DSC. It is found that the liquid crystalline phases much easier to be formed when the outer spacer is longer. When the outer spacer of dimesogenic compound is 8 méthylènes, it can form SmC∗, chiral nematic and an unidentified chiral Sm phases both in heating and cooling process.