Design, synthesis, and self-assembly behavior of C3-symmetry discotic molecules via click chemistry
作者:Mi-Hee Ryu、Jin-Woo Choi、Byoung-Ki Cho
DOI:10.1039/b921685e
日期:——
We prepared a series of C3-symmetry discogens with three 1,2,3-triazoles and a central benzene ring by a copper-catalyzed “click reaction” between 1,3,5-triethynylbenzene and 3,4,5-trialkoxybenzyl azides. According to the differential scanning calorimetry (DSC) data, compounds with octyl and dodecyl peripheries showed stable liquid crystalline (LC) phases at room temperature, and upon heating underwent an isotropization at 105.3 °C and 92.2 °C, respectively. Compound with octadecyl peripheries melted into a LC phase at 63.5 °C, and changed into a disordered liquid at 84.4 °C. As characterized by optical polarized microscopy (POM) and X-ray scattering techniques, all LC phases revealed hexagonally packed columns, the axes of which are aligned vertically on the glass substrate. Interestingly, the experimentally accessible crystalline phase of the compound with octadecyl chains kept the 2-D hexagonal columnar structure, although the interdisc distance within the columns changed at the transition from the LC to crystalline phase.
我们通过铜催化的“点击反应”,合成了一系列具有C3对称性的分子,包括三个1,2,3-三唑和一个中心苯环,反应物为1,3,5-三乙炔基苯和3,4,5-三烷氧基苄基叠氮化物。根据差示扫描量热法(DSC)数据,具有辛基和十二烷基外围的化合物在室温下显示出稳定的液晶(LC)相,分别在105.3 °C和92.2 °C时经历了各向同性化。具有十八烷基外围的化合物在63.5 °C时熔化为LC相,并在84.4 °C时转变为无序液体。通过光学偏光显微镜(POM)和X射线散射技术表征的结果显示,所有的LC相均呈现出六角形排列的柱状结构,柱子的轴线在玻璃基底上垂直排列。有趣的是,具有十八烷基链的化合物的实验可获得的晶相保持了二维六角形柱状结构,尽管在从液晶相过渡到晶相时,柱内的分子盘距发生了变化。