设计并合成了一类新型的4′-(4″-n-烷氧基亚苯基乙炔基) 4-n-己氧基偶氮苯及其两个系列的氟代化合物， 它们的相变行为通过差示扫描量热法和偏光显微镜进行了测试及观察， 发现它们均是液晶化合物， 都呈现向列相和近晶相， 并且发现该类化合物的相变行为与氟原子取代的数目与位置有着密切的关系。 相比较不含氟的同类化合物， 氟原子的引入降低了化合物的熔点和清亮点， 如果两个氟原子对称分布在液晶分子长轴向的两侧则有利于向列相的稳定性， 相反分布于分子长轴一侧的两个氟原子有利于近晶相的稳定性。
Three series of azobenzene liquid crystals containing a tolane unit were syn thesized. The mesomorphic properties of the compounds were characteriz ed by differential scanning calorimetry (DSC) and optical polarization microscop y (POM) . These series exhibit a nematic, a smectic A or a smectic B. This investi gation reveals that the mesomorphic properties have close relationship with the fluorosubstituents. The lateral substitution of two fluorines on both sides of the molecule′s long axis is advantageous to nematic phase, conversely, if the y lie in the same side, smectic phase is easy to exhibit.
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