Mesomorphic properties of multi-arm liquid crystals containing glucose and sorbitol as cores

Six thermotropic cholesteric multi-arm liquid crystals (MALCs) were synthesized with glucose and sorbitol as chiral cores. b0, b1 and b2 were introduced into hydroxy groups of the chiral cores as the mesogenic units in the arm scaffold. The roles played by the chiral cores and the terminal chain length of the mesogenic units to the mesomorphic behavior of the MALCs were studied. b0, b1 and b2 displayed nematic phase. c0, c1, c2, d0, d1 and d2 exhibited cholesteric phases and wide mesogenic regions. The results indicated that the chiral cores played an important effect on inducing the cholesteric phase and an obvious effect on the melting temperature, clear point and mesophase region of the MALCs. The corresponding melting temperature and the clear point of d0, d1 and d2, were lower than those of the c0, c1 and c2. The mesophase regions of the formers were narrower than those of the latters. The terminal chain length of the mesogenic units played an important effect on mesogenic region, too. The mesogenic region increased as the terminal chain length increasing for the MALCs containing the same chiral core.