论文部分内容阅读
为降低液晶分子的双折射率并获得宽液晶相区,用环己基替代传统二苯乙炔液晶分子中的一个苯环,得到一类结构新颖的含乙炔桥键的负介电各向异性液晶分子4a,4b.目标化合物采用1-trans-4-(trans-4-正戊基环己基)环己基乙炔与4-碘-2,3-二氟苯基醚进行Sonogashira偶联反应制备,反应总产率27%～28%.产物结构经MS,IR,NMR鉴定确认.采用DSC结合偏光显微镜对液晶相变温度进行了测试,结果表明新化合物4a,4b清亮点分别为212,216℃,向列相温区均达到140℃,与传统二苯乙炔类液晶的相变温区基本相当.物理性能测试表明,分子骨架共轭程度的削弱不仅使双折射率大幅降低,而且介电各向异性绝对值还有所增大,为分子设计提供了新的思路.新化合物综合性能得到显著改善,在大尺寸液晶电视领域具有非常好的应用前景.
In order to reduce the birefringence of liquid crystal molecules and obtain a wide liquid crystal phase region, a new type of acetylene bridged negative dielectric anisotropic liquid crystal molecules 4a, 4b. The title compound was prepared by Sonogashira coupling of 1-trans-4- (trans-4-n-pentylcyclohexyl) cyclohexyl acetylene with 4-iodo-2,3- The yield was 27% -28%. The structure of the product was confirmed by MS, IR and NMR. The liquid crystal phase transition temperature was measured by DSC combined with polarized light microscope. The results showed that the clearing points of new compounds 4a and 4b were 212,216 ℃, The temperature region reached 140 ℃, which is basically the same as the phase transition temperature range of the traditional liquid crystal of the benzenes.Physical property tests show that the weakening of the conjugation of the molecular skeleton not only greatly reduces the birefringence, but also the absolute value of the dielectric anisotropy But also increase the molecular design provides a new way of thinking.Comprehensive performance of the new compound has been significantly improved in the field of large-size LCD TV has a very good application prospects.