Enantiomeric separation of hydroxy acids and carboxylic acids by diamino-β-cyclodextrins (AB, AC, AD) in capillary electrophoresis

Selectively modified 6,6′‐dideoxy‐6,6′‐L‐diamino‐β‐cyclodextrins (AB, AC, AD) were successfully used as chiral selectors for the enantiomeric separation of hydroxy acids and carboxylic acids (in particular, phenoxyalkanoic acid herbicides) in capillary electrophoresis (CE). Chiral separations were o...

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Bibliographic Details
Published in:	Electrophoresis Vol. 22; no. 15; pp. 3171 - 3177
Main Authors:	Galaverna, Gianni, Paganuzzi, Maria Cristina, Corradini, Roberto, Dossena, Arnaldo, Marchelli, Rosangela
Format:	Journal Article
Language:	English
Published:	Hoboken Wiley Subscription Services, Inc., A Wiley Company 01-09-2001
Subjects:	beta-Cyclodextrins Capillary electrophoresis Carboxylic acids Carboxylic Acids - isolation & purification Cationic β-cyclodextrins Cyclodextrins - chemistry Electrophoresis, Capillary - methods Enantiomeric separation Herbicides - isolation & purification Hydrogen-Ion Concentration Hydroxy acids Hydroxy Acids - isolation & purification Magnetic Resonance Spectroscopy Phenoxyalkanoic acid herbicides Static Electricity Stereoisomerism
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Summary:	Selectively modified 6,6′‐dideoxy‐6,6′‐L‐diamino‐β‐cyclodextrins (AB, AC, AD) were successfully used as chiral selectors for the enantiomeric separation of hydroxy acids and carboxylic acids (in particular, phenoxyalkanoic acid herbicides) in capillary electrophoresis (CE). Chiral separations were obtained at a low selector concentration (1 mM) with good enantioselectivity and resolution factors. Separations were optimized as a function of pH. The different position of the charged groups on the upper rim greatly influenced the separation, accounting for electrostatic interactions between the protonated amino groups of the cyclodextrins (CDs) and the carboxylate of the selectands. The best enantiomeric separation of hydroxy acids was obtained with the AC regioisomer, whereas carboxylic acids were well resolved only by the AB regioisomer. A recognition model is proposed, based on two‐dimensional nuclear magnetic resonance (2‐D NMR) experiments, in which the orientation of the guest in the inclusion complex is determined by the electrostatic interactions between the selectand and the CD upper rim.
Bibliography:	ark:/67375/WNG-9873BVFT-Z istex:AA574E51D05DC68CDEFDB411E778007F8D21DE7E ArticleID:ELPS3171
ISSN:	0173-0835 1522-2683
DOI:	10.1002/1522-2683(200109)22:15<3171::AID-ELPS3171>3.0.CO;2-K