A thermodynamic approach to understanding liquid crystal selectivity in gas chromatography

The thermodynamics of four new liquid crystals were investigated in order to understand their selectivity as stationary phases in gas chromatography. In this case study, liquid crystals with a benzoyloxy azobenzene mesogenic core substituted with heptyloxy (C7) and/or dioxyethylene ether (DOE) groups, were used. The chromatographic separations of linalool and citronellal, and of xylene, tetraethylbenzene and cresol isomers, which were achieved with the liquid crystal stationary phases, have been related to the dissolution thermodynamics of the solutes. The results gave us an insight into the mechanism of the molecular recognition involved in the separation processes.