Synthesis and phase transitions of monomers carrying a biphenyleneazobenzene or an azotolane group. Precursors of photo-responsive liquid crystal polymers
作者:Olga Lidia Torres-Rocha、Leticia Larios-López、Rosa Julia Rodríguez-González、Isaura Felix-Serrano、Dámaso Navarro-Rodríguez
DOI:10.1016/j.molliq.2016.11.040
日期:2017.1
transitions of the monomers carrying a biphenyleneazobenzene core were much broader and weaker than those of monomers carrying an azotolane group. Also, the former showed no crystallization in cooling to room temperature. The four studied monomers displayed liquid crystal phases with lamellar order (SmA and SmC), but only those carrying an azotolane core developed an additional nematic phase. The lamellar
合成了四个官能的甲基丙烯酸酯单体,其中两个带有联苯撑偶氮苯基,另外两个带有偶氮戊烷基。合成途径涉及多个反应,其中铃木-宫浦和Sonogashira交叉偶联反应使我们能够制备长的刚性棒状偶氮苯核。质子核磁共振证实了这些新型偶氮单体的化学结构(11 H NMR)光谱,并通过差示扫描量热法(DSC),偏振光学显微镜(POM)和X射线衍射(XRD)分析确定了热致液晶行为。四种单体表现出在宽温度范围内延伸的介晶行为。带有联亚苯基偶氮苯核心的单体的相变比带有偶氮戊烯基的单体的相变宽得多和弱得多。另外,前者在冷却至室温时未显示出结晶。四种被研究的单体显示出层状有序的液晶相(SmA和SmC),但只有那些带有偶氮戊环核的单体才能形成附加的向列相。根据刚性棒状核之间的侧向相互作用讨论了单体的层状堆积。两种类型的单体均显示出紫外线照射后,反式到顺式的光转换率约为90%。这些新单体是光敏液晶聚合物的前体。