聚劳酯液晶硬核的构象与键级的理论研究

A THEORETICAL STUDY OF CONFORMATION AND BOND ORDER OF MESOGENIC CORES OF LIQUID CRYSTALLINE AROMATIC POLYESTERS

液晶已有一百年的历史了。液晶化学,液晶物理,液晶材料方面的科学都有了相当丰富的积累与长足的发展。十三年前Chandrase khar发现了碟形液晶,它具有特征的二维有序的柱状液晶相。从学术上讲,该发现对液晶科学的一些概念有一定的冲击,传统的有关液晶的分类(向列型、胆甾型、近晶型)正在被更加合理的从液晶分子聚集结构的几何特性而进行的分类(向列相、层状相、柱状相)所取代。

PCILO conformational calculations have been carried out on several model compounds of mesogenic cores of liquid crystalline aromatic polyesters,-CO-O--O-CO-,-CO -O-CO-O- and -O-CO-CO-O-.The calculated structures can be compared to the X-ray crystallographic data. In addition, bond orders of the model compounds were also obtained by using CNDO. It has been found that the three phenylene rings statistically take orientations perpendicular to each other, and that when the carbonyl group turns into plane of the phenylene ring which is not the immediate neighbor but the one through the ether-oxygen, the best conjugation reached is not accompanied by the lowest conformational energy.