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 ~(13)C 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~deg and the ring-ring linkages in the biphenyl groups are tilted with the dihedral angle of around 43-44~deg 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 ~(13)C chemical shifts of carbonyl carbons were found to move to upfield due to pi-conjugation with phenyl ring and slightly affected about 0.5 ppm by dihedral angle of the ring-ring linkage.
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