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Comparative analysis of the full set of methylated β‐cyclodextrins as chiral selectors in capillary electrophoresis
Author(s) -
Varga Erzsébet,
Benkovics Gábor,
Darcsi András,
Várnai Bianka,
Sohajda Tamás,
Malanga Milo,
Béni Szabolcs
Publication year - 2019
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.201900134
Subject(s) - enantiomer , chemistry , capillary electrophoresis , terbutaline , cyclodextrin , structural isomer , beta cyclodextrins , combinatorial chemistry , solubility , chromatography , organic chemistry , medicine , asthma
The chiral separation ability of the full library of methylated‐β‐cyclodextrins towards pharmacologically significant racemic drugs including basic compounds was studied by chiral CE. The syntheses of all the methylated, single isomer β‐cyclodextrins were revised and optimized and the aqueous solubility of the derivatives was unambiguously established. The three most relevant commercially available methylated isomeric mixtures were also included in the screening, so a total of ten various methylated CDs were investigated. The effects of the selector concentration on the enantiorecognition properties at acidic pH were investigated. Among the dimethylated β‐cyclodextrins, the heptakis (2,6‐di‐ O ‐methyl)‐β‐cyclodextrin isomer (2,6‐DIMEB) resulted to be the most versatile chiral selector. Terbutaline was selected as a model compound for the in‐depth investigation of host‐guest enantiodiscrimination ability. The association constants between the two terbutaline enantiomers and 2,6‐DIMEB were determined in order to support that the enantioseparation is driven by differences is host‐guest binding. The migration order of the enantiomers was confirmed by performing spiking experiments with the pure enantiomers. 1D and 2D NMR spectroscopy was applied to the 2,3‐, and 2,6‐DIMEB/terbutaline systems to rationalize at molecular level the different enantioseparation ability of the dimethylated β‐cyclodextrin selectors.