Sorption and selective chromatographic properties of isomer-selective composite sorbent based on a eutectic mixture of nematic liquid crystals and perbenzoylated β-cyclodextrin

Abstract

Mesomorphic, sorption, and selective properties of a three-component sorbent based on a mixture of nematic (N) liquid crystals of 4-methoxy-4′-ethoxyazoxybenzene (MEAB) and 4,4′-diethoxyazoxybenzene (azoxyphenetol, AOP) of an eutectic composition and heptakis-(2,3,6-tri-O-benzoyl)-β-cyclodextrin (Bz-β-CD) are studied. For 30 organic compounds of different classes with linear and cyclic molecular structures, including optical isomers of limonene, pinene, camphene, and butanediol-2,3, thermodynamic functions are determined for their gas-phase sorption using a three-component MEAB-AOP-Bz-β- CD sorbent (62: 28: 10 wt %). It is found that the investigated sorbent possesses high structural selectivity (αp/m = 1.128–1.059, 100–130°C, N) and moderate enantioselectivity (1.07–1.02) within a broad temperature range (95–170°C) including both mesomorphic and isotropic phases of the sorbent. It is shown that the enantioselectivity of the sorbent is apparent under conditions of both increasing retention when a chiral Bz-β-CD additive is introduced into the MEAB–AOP system (limonenes, pinenes, camphenes) and decreasing retention (butanediols-2,3).