Dependence of solute orientational order on the structure and orientational order of the liquid crystal solvent. A deuterium N.M.R. study ofp-xylene-d10dissolved in a series of 4-n-alkyloxy-4′-cyanobiphenyls

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Abstract
The quadrupolar splittings from the ring and methyl deuterons have been used to determine the principal components Szz and Sxx - Syy of the second rank orientational ordering matrix for p-xylene dissolved in the first 12 members of the 4-n-alkyloxy-4′-cyanobiphenyls (NOCB). The two order parameters are used to obtain the coefficients a and b in a potential of mean torque for the solute molecules at infinite dilution in the solvent. The ratio λexp = b/2a, which is a measure of the departure of U (β2γ2) from cylindrical symmetry, is found to vary with temperature for each solute-solvent pair, and to increase as N, the number of chain carbon atoms, increases. The dependences of aRT and bRT on the orientational order of the solvent is explored.