An internal order approach to the investigation of intramolecular rotations in liquid crystals by NMR: 3-Phenyl-thiophene in PCH and phase IV

The internal order parameter formalism is used to analyze the proton NMR spectrum of 3-phenyl-thiophene in two nematic phases: PCH and phase IV. Using a maximum-entropy approach we have obtained from the experimental dipolar couplings purely orientational order parameters for the two rings as well as an approximate rotamer distribution. The distribution in PCH peaks at 27° with a much smaller hump at 90° while the distribution in phase IV again peaks at 27° but is much broader, suggesting a noticeable solvent effect. © 1988.