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Enantioseparation of chiral N ‐imidazole derivatives by electrokinetic chromatography using highly sulfated cyclodextrins: Mechanism of enantioselective recognition
Author(s) -
Danel Cécile,
Lipka Emmanuelle,
Bonte JeanPaul,
Goossens JeanFrançois,
Vaccher Claude,
Foulon Catherine
Publication year - 2005
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/elps.200500078
Subject(s) - enantiomer , chemistry , analyte , enantioselective synthesis , imidazole , electrokinetic phenomena , cyclodextrin , sulfation , chromatography , combinatorial chemistry , stereochemistry , organic chemistry , catalysis , biochemistry
Baseline separation of ten new substituted [1‐(imidazo‐1‐yl)‐1‐phenylmethyl)] benzothiazolinone and benzoxazolinone derivatives, with one chiral center, was achieved by CD‐EKC using highly sulfated CDs (α, β, γ highly S‐CDs) as chiral selectors. The influence of the type and concentration of the chiral selectors on the enantioseparations was investigated. The highly S‐CDs exhibit a very high enantioselectivity power since they allow excellent enantiomeric resolutions compared to those obtained with the neutral CDs. The enantiomers were resolved with analysis times inferior to 2.5 min and resolution factors R s of 3.73, 3.90, 1.40, and 4.35 for compounds 1 , 2 , 3 , and 5 , respectively, using 25 m M phosphate buffer at pH 2.5 containing either highly S‐α‐CD, highly S‐β‐CD, and highly S‐γ‐CD (3 or 4% w/v) at 298 K, with an applied field of 0.30 kV/cm. The determination of the enantiomer migration order for the various analytes and the study of the analyte structure–enantioseparation relationships display the high contribution of the interactions between the analytes phenyl ring and the CDs to the enantiorecognition process. The thermodynamic study of the analyte–CD affinities permits us to improve our knowledge about the enantioseparation mechanism.