title: High-performance liquid chromatographic enantioseparation of fluorinated cyclic β(3) -amino acid derivatives on polysaccharide-based chiral stationary phases. Comparison with nonfluorinated counterparts.
abstract: The stereoisomers of five fluorinated cyclic β(3) -amino acid derivatives and their nonfluorinated counterparts were separated on chiral stationary phases containing as chiral selectors cellulose tris-(3,5-dimethylphenyl carbamate), cellulose tris-(3-chloro-4-methylphenyl carbamate), cellulose tris-(4-methylbenzoate), cellulose tris-(4-chloro-3-methylphenyl carbamate), amylose tris-(3,5-dimethylphenyl carbamate) or amylose tris-(5-chloro-2-methylphenyl carbamate). The enantioseparations were carried out in normal-phase mode with n-hexane/alcohol/alkylamine mobile phases in the temperature range 5-40 °C. The effects of the mobile phase composition, the nature and concentration of the alcohol and alkylamine additives, the structures of the analytes and temperature on the separations were investigated. Thermodynamic parameters were calculated from plots of ln α vs. 1/T. The Δ(ΔH°) values ranged between -5.0 and +1.6 kJ/mol, while Δ(ΔS°) varied between -12.6 and +5.7 J/mol/K. The enantioseparation was enthalpically controlled, the retention factor and the separation factor decreasing with increasing temperature, but entropically controlled separation was also observed. The elution sequence was determined for all of the investigated analytes. Copyright © 2016 John Wiley & Sons, Ltd.
authors.affiliation: Department of Inorganic and Analytical Chemistry, University of Szeged, H-6720, Szeged, Dóm tér 7, Hungary.|Institute of Pharmaceutical Chemistry and Research Group for Stereochemistry, Hungarian Academy of Sciences, University of Szeged, H-6720, Szeged, Eötvös u. 6, Hungary.
authors.forename: Gyula
authors.initials: G
authors.lastname: Lajkó
authors.affiliation: Department of Inorganic and Analytical Chemistry, University of Szeged, H-6720, Szeged, Dóm tér 7, Hungary.
authors.forename: Tímea
authors.initials: T
authors.lastname: Orosz
authors.affiliation: Institute of Pharmaceutical Chemistry and Research Group for Stereochemistry, Hungarian Academy of Sciences, University of Szeged, H-6720, Szeged, Eötvös u. 6, Hungary.
authors.forename: Lóránd
authors.initials: L
authors.lastname: Kiss
authors.affiliation: Institute of Pharmaceutical Chemistry and Research Group for Stereochemistry, Hungarian Academy of Sciences, University of Szeged, H-6720, Szeged, Eötvös u. 6, Hungary.
authors.forename: Enikő
authors.initials: E
authors.lastname: Forró
authors.affiliation: Institute of Pharmaceutical Chemistry and Research Group for Stereochemistry, Hungarian Academy of Sciences, University of Szeged, H-6720, Szeged, Eötvös u. 6, Hungary.
authors.forename: Ferenc
authors.initials: F
authors.lastname: Fülöp
authors.affiliation: Department of Inorganic and Analytical Chemistry, University of Szeged, H-6720, Szeged, Dóm tér 7, Hungary.
authors.forename: Antal
authors.initials: A
authors.lastname: Péter
authors.affiliation: Department of Inorganic and Analytical Chemistry, University of Szeged, H-6720, Szeged, Dóm tér 7, Hungary.
authors.forename: István
authors.initials: I
authors.lastname: Ilisz
mesh_terms: D000596:Amino Acids / Q000737:chemistry / Q000302:isolation & purification*; D002851:Chromatography, High Pressure Liquid / Q000295:instrumentation / Q000379:methods*; D005461:Fluorine / Q000737:chemistry*; D011134:Polysaccharides / Q000737:chemistry*; D013237:Stereoisomerism; D013696:Temperature; D013816:Thermodynamics
chemical_list: D000596:Amino Acids; D011134:Polysaccharides; D005461:Fluorine
keywords: direct enantioseparation of fluorinated cyclic β3-amino acid derivatives; high-performance liquid chromatography (HPLC); temperature dependence of chiral separation