四原子中心桥键联苯酯类液晶的合成与性质

Synthesis and properties of the biphenol ester liquid crystals containing four unit linking groups

设计了简单的合成路线和方法合成了两个系列，共１２种具有四原子中心桥键的联苯酯类化合物。通过红外光谱、核磁共振谱、质谱和元素分析确认了化合物的结构，用偏光显微镜和微分扫描量热仪（ＤＳＣ仪）确定了化合物的液晶相态和相变温度。这些化合物分子的共轭程度和刚性较大，尤其是丙烯酸酯类化合物（系列Ⅱ）具有较高的清亮点和宽的介晶相温度范围。同系列化合物的末端烷基链（Ｒ）碳原子数与清亮点的关系呈现奇偶效应。

Two series(Ⅰ,Ⅱ),12 compounds, were synthesized by using a simple synthetic method. Their structures were determined by IR, NMR and MS. The phase transition temperatures were measured by DSC, mesomorphic textures were recognized by polarized microscopy. Ester derivatives of propenoic acid have high clearing points and broad mesophase temperature ranges because of the large conjugation and rigidity existed in these molecules. The clearing points of homologous compounds show the oddeven effect with changing number of carbon atom of terminal alkyl group. Linking groups which contain oddnumber atoms lead to the suppression of tendencies forming liquid crystal, and the compounds containing evennumber atoms linking group exhibit nematic liquid crystal phases.