An interpretation of the anomalous results from a nuclear magnetic resonance study of13C-methanol partially oriented in nematic liquid crystalline phases

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Abstract
Methanol has been studied in several liquid crystalline solvents. Anomalous structural results were obtained from thermotropic phases and were interpreted in terms of exchange between two orientations with opposite signs of the order along the C3 axis. The details of a two-site theory were developed and it was found that meaningful structural information could still be obtained from the averaged dipolar couplings observed. The theory also showed that the determination of quadrupole coupling constants and chemical shift anisotropies should give non-constant results when obtained from such an averaging system. This was confirmed by a study of several small molecules, using deuterium magnetic resonance. All gave nonconstant quadrupole coupling constants. Preliminary investigations of lyotropic phases indicated that, at least for methanol, these systems behave normally.