19F Nuclear magnetic resonance spectrum of pentafluoropyridine partially oriented in a nematic phase

Abstract

The n.m.r. spectrum of pentafluoropyridine dissolved in a nematic phase has been analyzed for four samples of different concentrations. From the results it has been possible to assign the magnitudes and signs of all the FF coupling constants. The contribution of anisotropic spin coupling to dipolar coupling is probably negligible, and it has therefore been possible to obtain the independent elements of the ordering matrix for each concentration. For one concentration a relationship is obtained for each fluorine nucleus between the observed nematic-isotropic change in shielding and principal components of the shift tensor.