INFLUENCE OF THE MOLECULAR-STRUCTURE OF A NEMATIC SOLVENT ON HYDROGEN-BONDING WITH NON-MESOMORPHIC PROTON DONORS

The concentration dependence of the orientational order parameter of a cetic acid dissolved in nematic solvents has been generated by compute r simulation on the basis of an equilibrium model for liquid crystalli ne solutions containing non-mesogenic solutes. Comparison of this pred icted dependence with experiment allows the equilibrium constants, ori entational correlation coefficients on non-mesogenic solutes in hydrog en bonded complex and the dimer to be calculated. Data in the structur e of H-complexes involving the liquid crystal and the solute have been obtained. Regularities in the influence of II-bonds on the ability of the solute to destabilize the nematic phase. (beta(NI)) have been est ablished. The strengthening of the longitudinal complex is shown to re sult in a lowering and for the transversal complex - in an enhancing o f beta(NI). The thermodynamic characteristics of alcohols dissolved in nematic Schiff's bases and 4-n-hexyloxy-4'-cyanobiphenyl were obtaine d by gas-liquid chromatography. An even-odd alternation of Delta (H) o ver bar(2) and Delta (S) over bar(2) alcohol series has been found. It is shown that the direction of the alternation depends on the alignme nt of the molecular components in the H-complex.