title: Structural and temperature effects on enantiomer separations of bicyclo[2.2.2]octane-based 3-amino-2-carboxylic acids on cinchona alkaloid-based zwitterionic chiral stationary phases.
abstract: Procedures for the direct high-performance liquid chromatographic enantiomer separation of four bicyclo[2.2.2]octane-based 3-amino-2-carboxylic acids were developed in polar-ionic mode on zwitterionic chiral stationary phases (CSPs) based on cinchonane alkaloide quinine, quinidine and chiral sulfonic acid motifs. The effects of the mobile phase composition including the type of acid and base additives, the structures of the analytes and temperature were investigated. Experiments were performed at constant mobile phase compositions in the temperature range 10-50°C in order to study the effects of temperature, and thermodynamic parameters were calculated from plots of ln k or ln α vs. 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 enantiomeric separations were in most cases enthalpically driven, but entropically driven separation was also observed. The sequence of elution of the enantiomers on the pseudo-enantiomerically behaving CSPs was determined in all cases.
authors.affiliation: Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, H-6720 Szeged, Hungary.
authors.forename: István
authors.initials: I
authors.lastname: Ilisz
authors.affiliation: Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, H-6720 Szeged, Hungary; Institute of Pharmaceutical Chemistry, University of Szeged, Eötvös u. 6, H-6720 Szeged, Hungary.
authors.forename: Nóra
authors.initials: N
authors.lastname: Grecsó
authors.affiliation: Institute of Pharmaceutical Chemistry, University of Szeged, Eötvös u. 6, H-6720 Szeged, Hungary.
authors.forename: Márta
authors.initials: M
authors.lastname: Palkó
authors.affiliation: Institute of Pharmaceutical Chemistry, University of Szeged, Eötvös u. 6, H-6720 Szeged, Hungary.
authors.forename: Ferenc
authors.initials: F
authors.lastname: Fülöp
authors.affiliation: Department of Analytical Chemistry, University of Vienna, Währingerstrasse 38, 1090 Vienna, Austria.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Lindner
authors.affiliation: Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, H-6720 Szeged, Hungary. Electronic address: apeter@chem.u-szeged.hu.
authors.forename: Antal
authors.initials: A
authors.lastname: Péter
mesh_terms: D002264:Carboxylic Acids / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D002930:Cinchona Alkaloids / Q000737:chemistry*; D007477:Ions / Q000737:chemistry; D009795:Octanes / Q000737:chemistry*; D013237:Stereoisomerism; D013696:Temperature; D013816:Thermodynamics
chemical_list: D002264:Carboxylic Acids; D002930:Cinchona Alkaloids; D007477:Ions; D009795:Octanes; C026728:octane
keywords: Bicyclo[2.2.2]octane-based 3-amino-2-carboxylic acids; Enantiomer separation; HPLC; Temperature effect; Zwitterionic chiral stationary phases