title: Investigation of the structure-selectivity relationships and van't Hoff analysis of chromatographic stereoisomer separations of unusual isoxazoline-fused 2-aminocyclopentanecarboxylic acids on Cinchona alkaloid-based chiral stationary phases.
abstract: The enantiomers of four unusual, rather rigid isoxazoline-fused 2-aminocyclopentanecarboxylic acids were directly separated on a quinine- or a quinidine-based zwitterionic ion-exchanger as chiral selector. The effects of the mobile phase composition, the structures of the analytes and temperature on the separations were investigated. Experiments were performed at constant mobile phase composition in the temperature range 10-50°C to study the effects of temperature, and thermodynamic parameters were calculated from plots of ln α versus 1/T. Some mechanistic aspects of the chiral recognition process are discussed with respect to the structures of the analytes. It was found that the enantiomer separations were in most cases predominantly enthalpy-driven, but entropically-driven separations were also observed. The sequence of elution of the enantiomers was determined in all cases.
authors: Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, H-6720 Szeged, Hungary.
authors: István
authors: I
authors: Ilisz
authors: Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, H-6720 Szeged, Hungary; Institute of Pharmaceutical Chemistry, University of Szeged and Stereochemistry Research Group of the Hungarian Academy of Sciences, Szeged, Eötvös u. 6, H-6720, Hungary.
authors: Zsanett
authors: Z
authors: Gecse
authors: Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, H-6720 Szeged, Hungary; Institute of Pharmaceutical Chemistry, University of Szeged and Stereochemistry Research Group of the Hungarian Academy of Sciences, Szeged, Eötvös u. 6, H-6720, Hungary.
authors: Gyula
authors: G
authors: Lajkó
authors: Institute of Pharmaceutical Chemistry, University of Szeged and Stereochemistry Research Group of the Hungarian Academy of Sciences, Szeged, Eötvös u. 6, H-6720, Hungary.
authors: Melinda
authors: M
authors: Nonn
authors: Institute of Pharmaceutical Chemistry, University of Szeged and Stereochemistry Research Group of the Hungarian Academy of Sciences, Szeged, Eötvös u. 6, H-6720, Hungary.
authors: Ferenc
authors: F
authors: Fülöp
authors: Department of Analytical Chemistry, University of Vienna, Währinger Strasse 38, A-1090 Vienna, Hungary.
authors: Wolfgang
authors: W
authors: Lindner
authors: Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, H-6720 Szeged, Hungary. Electronic address: apeter@chem.u-szeged.hu.
authors: Antal
authors: A
authors: Péter
mesh_terms: D002264:Carboxylic Acids / Q000302:isolation & purification*; D002845:Chromatography; D002930:Cinchona Alkaloids / Q000737:chemistry*; D003515:Cycloleucine / Q000737:chemistry; D059625:Liquid-Liquid Extraction / Q000379:methods*; D011803:Quinine / Q000737:chemistry; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D013696:Temperature; D013816:Thermodynamics
chemical_list: D002264:Carboxylic Acids; D002930:Cinchona Alkaloids; D003515:Cycloleucine; D011803:Quinine
keywords: Chiralpak ZWIX columns, van’t Hoff analysis, Unusual temperature effects; Cinchona alkaloid-based chiral stationary phases; Column liquid chromatography; Isoxazoline-fused 2-aminocyclopentanecarboxylic acids