作者:Md Lutfor Rahman、Gurumurthy Hegde、Mashitah Mohd Yusoff、Muhammad Nor Fazli A. Malek、Hosapalya T. Srinivasa、Sandeep Kumar
DOI:10.1039/c3nj00359k
日期:——
The first examples of liquid crystalline pyrimidine-based photo-switchable bent-core monomers incorporating azobenzene as side arms linked with terminal double bonds as polymerizable functional groups are synthesized and characterized. Polarizing optical microscopy (POM), differential scanning calorimetry (DSC) and X-ray diffraction analysis reveal that the bent-shaped lower homologue compounds are crystalline in nature whereas higher homologue compounds display the stable enantiotropic B6 phase. They exhibit fast photoisomerization effects in solution and relatively slow photoisomerization effects in liquid crystal cells. In solution both trans–cis and cis–trans occur at around 3 s and 200 s, respectively, whereas in solids they occur at around 10 s to 200 min. These are some of the first examples of azobenzene liquid crystals which exhibit very fast switching properties in solutions.
我们合成并表征了首例液晶嘧啶基光开关弯曲核单体,这些单体以偶氮苯为侧臂,以末端双键为可聚合官能团。偏光光学显微镜(POM)、差示扫描量热仪(DSC)和 X 射线衍射分析表明,弯曲形状较低的同族化合物为结晶性质,而较高的同族化合物则显示出稳定的对映体 B6 相。它们在溶液中表现出快速的光异构化效应,而在液晶池中则表现出相对缓慢的光异构化效应。在溶液中,反式-顺式和顺式-反式分别在 3 秒和 200 秒左右发生,而在固体中,则在 10 秒到 200 分钟左右发生。这是偶氮苯液晶在溶液中表现出极快切换特性的首例。