Combined approach using capillary electrophoresis and NMR spectroscopy for an understanding of enantioselective recognition mechanisms by cyclodextrins

Abstract

This tutorial review describes the contribution of chiral capillary electrophoresis in combination with other instrumental techniques, especially nuclear magnetic resonance spectroscopy, to a better understanding of the chiral recognition mechanisms by cyclodextrins. Aspects such as affinity pattern of enantiomers towards various cyclodextrins as well as the stoichiometry of the resulting complexes, the equilibrium constants and the structure of complexes are addressed. In addition to the aforementioned techniques, the usefulness of complementary instrumental and molecular modeling techniques for an understanding of the chiral recognition mechanisms of cyclodextrins is also illustrated.

Enantioselective separation of azole compounds by EKC. Reversal of migration order of enantiomers with CD concentration

“…CE has a great potential for chiral separations because it offers interesting advantages (fast screening, high peak efficiency, and flexibility) for the detection of very fine enantioselective effects. Moreover, this technique is very useful in order to study analyte-CD binding interactions, since it enables the measurement of binding constants exactly under the same conditions under which enantioseparations are performed without adaptations or approximations [5,8,9]. Another interesting aspect of CE is the possibility of changing the migration order of the enantiomers of a chiral compound.…”

“…Enantioseparations by CE rely on the same principle as in chromatographic techniques, that is, in the enantioselective interaction between a chiral selector and the chiral analyte using mainly the CE mode named EKC [1][2][3][4][5][6][7]. CE has a great potential for chiral separations because it offers interesting advantages (fast screening, high peak efficiency, and flexibility) for the detection of very fine enantioselective effects.…”

Supramolekulare Chemie in Wasser

“…Einige Rezeptorklassen wie die Cyclodextrine, [14] Kronenether [15,16] und Azamakrocyclen [17,18] werden wegen der zahlreichen Publikationen, die diese relativ einfachen wasserlöslichen supramolekularen Systeme behandeln, nicht aufgenommen. Der nächste Abschnitt befasst sich mit Selbstorganisation in Wasser, beispielsweise mit Kapseln, Helicaten, metall-organischen Makrocyclen und Käfigen.…”

Chiral recognition of ethers by NMR spectroscopy

“…), [27][28][29] dirhodium tetracarboxylate complexes, 30 or other organometallic systems. Chiral hosting compounds such as cyclodextrins, [31][32][33] calixar-enes 34 and others have been employed. Among those many techniques, which is the method of choice depends very much on the structure of the substrate molecules, particularly on the presence or absence of certain functional groups participating in the interaction with the chiral auxiliary.…”