Stationary Phase for Gas Chromatography on the Basis of a Precursor of Macroheterocycles and a Nematic Liquid Crystal

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The stationary phase for gas chromatography on the basis of the chiral R(+)-1′,7′,7′-trimethylbicyclo-[2.2.1]heptano[2′,3′-b]-2,3-dicyanopyrazine (10.4 wt %) and a liquid crystalline 4,4′-dihexyloxyazoxybenzene was studied. The phase transition temperatures of the binary mixture were measured by polarizing microscopy. It was shown that the chiral camphor-substituted 2,3-dicyanopyrazine induces formation of an enantiotropic chiral helically coiled nematic phase in the achiral liquid crystal over a wide temperature range. The gas chromatographic retention times of organic compounds on this sorbents were measured. The structural and chiral selectivity of the stationary phase on the basis of a liquid crystal and camphor-substituted 2,3-dicyanopyrazine was determined. The retention volumes, activity coefficients, and sorption enthalpies and entropies were calculated and analyzed.