Conformational Study of Liquid Crystalline Polymer: Theoretical Studies

Bulletin of the Korean chemical society

Mi Jung Lee¹  Dong Hee Kim¹ 

关键词: Liquid crystalline;    Conformation;    13C chemical shift;    Calculation;   

DOI  :  

学科分类：化学（综合）

来源: Korean Chemical Society

【 摘 要 】

The relaxed torsional potential of a liquid crystalline polymer containing an ester functional group in a mesogenic unit (hereafter 12-4 oligomer) has been calculated with the ab initio self-consistent-field using 6- 31G* basis set. GIAO ¹³C NMR chemical shifts also have been calculated at the B3LYP/6-31G* level of theory for each conformational structure obtained from torsional potential calculation. The results show that the phenyl ring-ester linkages are coplanar with the dihedral angle of about 0�? and the ring-ring linkages in the biphenyl groups are tilted with the dihedral angle of around 43-44�? in the lowest energy conformer. The biphenyl ring has a comparatively lower energy barrier of internal rotation potential in the ring-ring than that of phenyl ring-ester. The ¹³C chemical shifts of carbonyl carbons were found to move to upfield due to �? - conjugation with phenyl ring and slightly affected about 0.5 ppm by dihedral angle of the ring-ring linkage.

【 授权许可】

Unknown