含乙烯基末端的液晶二聚体的合成与液晶行为研究

Synthesis and Mesomorphism of Liquid Crystalline Dimers with Vinyl-Terminals

合成了一种新型的末端含不饱和双键的席夫碱类液晶化合物，分子结构中含有刚性酯类液晶基元及亚胺间隔基结构，并通过扫描量热（DSC）和偏光显微镜（POM）对其介晶相转变行为进行了表征。结果表明该二聚体与单体表现出不同的液晶行为，二聚体不仅具有向列相（N）液晶结构（120～139℃），且在低温区间显示出层状的近晶C型（SmC）液晶结构（91～120℃），液晶稳定性明显高于单体（单体液晶相温度范围为45～64℃）。实验结果为合成稳定的液晶化合物提供了实验依据。

A novel Schiff-base type liquid crystal compound with reactive vinyl terminals and flexible spacer was synthesized. The structure of this dimeric compound was characterized by FT-IR, 1H-NMR, 13C-NMR, ESI-MS. The liquid crystalline behavior of the compound characterized by differential scanning calorimetry （DSC） and polarizing optical microscopy （POM） is different from that of monomer. For the liquid crystal dimer, typical nematic phase texture can be observed between 120℃ and 139℃. Moreover, smectic C phase was also found between 91℃ and 120℃. The dimeric compound exhibits wider mesophase temperature ranges than that of monomer, which indicates higher mesomorphic stability. This result is available for the synthesis of liquid crystal compounds with high mesophase stability.