异硫氰基嘧啶乙炔类液晶合成及性能研究

Synthesis and properties of isothiocyanato pyrimidine acetylene liquid crystals

中心环外侧嘧啶环作为液晶分子的极性介晶基团,能有效增大分子的偶极矩和分子间的作用力,提高分子的介电各向异性,降低液晶的驱动电压,也有利于形成近晶相液晶态。本文试图以嘧啶乙炔为中心结构单元,以异硫氰基为端基,设计合成了嘧啶乙炔类异硫氰基液晶化合物(nBTM-NCS)系列共5个化合物;它们都经过IR、~1H-NMR、^(13)C-NMR和MS光谱对其分子结构鉴定,经过差热分析仪(DSC)和偏光显微镜(POM)对其液晶性能进行检测。实验结果表明,所有化合物的分子结构均正确,具有近晶相态,其熔点较高并呈现奇偶效应;其光学各向异性达到0.45左右,介电常数21~24左右,可作为铁电液晶和聚合物分散液晶材料配方组分。

The pyrimidine ring outside of the rigid core ring of liquid crystal molecules used as a polar mesogenic group,can effectively increase the molecular dipole moment and intermolecular force,improve the dielectric anis-otropy of the compounds,reduce the driving voltage of the liquid crystal,and also favor to form some smec-tic phases.In this paper,where pyrimidine acetyleneisused as the central structural unit and isothiocyanide asthe end group,we could see that a series of liquid crystal compounds（nBTM-NCS）about five compounds were designed and synthesized.The molecular structure of all compounds were identified by IR,-1H-NMR,-（13）C-NMR and MS spectra,and their liquidcrystal properties were measured by differential thermal analyzer（DSC）and polarizing microscope（POM）.The experimental results show that all the compounds have the correct molecular structure and smectic phases.The melting point of the compounds is high and it shows a parity effect.Its optical anisotropy reaches about 0.45,and the dielectric constant is about 22 to 24.It can be used as the components for ferroelectric liquid crystals and polymer-dispersed liquid crystal materials.