A simple model for RPLC retention and selectivity of imidazole enantiomers using β-cyclodextrin as chiral selector

Abstract

Using reversed phase liquid chromatography (RPLC), this paper investigates the enantioselectivity variations, in a series of weak polar R, S-imidazole derivatives, with β-cyclodextrin concentration in the mobile phase over a wide range of column temperatures. These compounds are used for the treatment of onychomycosis. The selectivity data obtained were assessed using a chiral recognition model, based on the formation of complexes between the solute molecule and the cyclodextrin cavity. Gibbs Helmholtz parameters (Δ(ΔH), Δ(ΔS)) between R- and S- enantiomers were determined from the logarithm of the separation factor, α, versus the reciprocal of the temperature plots. The thermodynamic results predicted that the enantioselectivity mechanism was related to both the solute's bulkiness and the asymmetric carbon atom configuration.