Dideuterium as solute in nematic liquid crystals

Deuteron NMR experiments on dideuterium dissolved in the nematic liquid-crystal solvents 7CB, CCH7, MBBA and PCH7 are reported as a function of temperature. The results are analysed in terms of the average solvent electric field gradient anisotropy (efg) felt by D2 which is positive with respect to the director in 7CB, CCH7 and PCH7 and negative in MBBA. The order parameter of D2 is to a large extent rationalized in terms of the interaction between this solvent efg and the solute D2 molecular quadrupole moment, and its sign is the same as that of the efg.