Thermodynamics of solutions of polycyclic aromatic hydrocarbons studied by gas—liquid chromatography with a nematic and an isotropic stationary phase

Abstract

Thermodynamic solution parameters of the isomeric polycyclic aromatic hydrocarbons phenanthrene and anthracene at infinite dilution in the nematic liquid crystal N,N′-bis( p-methoxybenzylidene)-α,α′-bi- p-toluidine (BMBT) and in its isotropic analogue N,N′-bis( p-methoxybenzylidene)-4,4′-diaminodiphenylmethane (BMBDM) have been derived by gas—liquid chromatography. The unique selectivity exhibited by BMBT towards isomeric polycyclic aromatic hydrocarbons is explained in the light of a current solution theory in terms of differences in the partial molar enthalpies and entropies of solution. Differences in solution behaviour between BMBT and BMBDM are examined with infinite-dilution solute activity coefficient, partial molar excess enthalpy and entropy data.