Rigid Phenylene Ethynylene Units Linked by A V-shaped Centre. An Approach to Biaxial Nematogens?
作者:Matthias Lehmann、Jérémy Levin
DOI:10.1080/15421400490435260
日期:2004.1
theoretical predictions that nematic phases formed from V-shaped compounds could be biaxial, shape-persistent phenylene ethynylene arms linked by 1,3-phenylene, 4,4′-diphenylenemethane and 3,6-fluorenone units have been synthesised. Crystallisation and micro-segregation is prevented by 2,5-alkoxy substitution on the middle benzene ring of the arms. The specific molecular engineering, i.e. variation
受到理论预测的鼓舞,即由 V 型化合物形成的向列相可以是双轴、形状持久的亚苯基亚乙炔臂,由 1,3-亚苯基、4,4'-二亚苯基甲烷和 3,6-芴酮单元连接。臂中间苯环上的 2,5-烷氧基取代可防止结晶和微偏析。特定的分子工程,即外围取代基 (H, CN) 的变化和不同长度的侧链烷氧基链,导致含有芴酮的材料 II3d 和 II3d 与非介晶 II3b 的混合物在很宽的温度范围内形成对映向列型液晶。这些中间相在环境温度下固化并形成向列玻璃。