作者:Timothy M. Long、Timothy M. Swager
DOI:10.1039/b203160d
日期:——
We report the synthesis of a new class of nematic liquid crystals with triptycenes built into a p-dialkoxy-bis(phenylethynyl)benzene mesomorphic core. Triptycenes are appended on the center or terminal ring of the mesogen, leading to symmetric liquid crystals and reduced symmetry liquid crystals, respectively. Both types displayed monotropic behavior, with the asymmetric compounds having unusual phase behavior, lacking distinct crystallization transitions, and forming a glassy mesophase. A chiral analogue was found to be non-mesomorphic, but induced chiral nematic phases when doped into achiral triptycene-containing analogues. Rotation is physically hindered normal to the director and, hence, this new liquid crystal architecture may allow for the synthesis of a single component liquid crystal that displays a biaxial nematic phase.
我们报道了一类新型向列相液晶的合成,其结构中将三苯并环庚三烯嵌入到对二烷氧基双(苯乙炔基)苯的介观核心中。三苯并环庚三烯可以附加在介晶的中心环或末端环上,分别得到对称型液晶和降低对称性的液晶。两种类型的液晶均表现出单向性行为,非对称化合物具有不同寻常的相态行为,缺乏明显的结晶转变,并形成了玻璃态介相。找到了一种手性类似物,该类似物本身不具有液晶性,但当掺入非手性的含三苯并环庚三烯的类似物中时,能诱导出手性向列相。沿指向矢法线方向的旋转受到物理阻碍,因此,这种新型液晶结构可能允许合成一种单组分液晶,显示双轴向列相。