Capillary electrophoresis and H-1 NMR studies on chiral recognition of atropisomeric binaphthyl derivatives by cyclodextrin hosts

The usefulness of H-1 NMR spectroscopy is illustrated for a detailed study of a selector-solute interactions which maintain enantioseparations in capillary electrophoresis. The apparent binding constants (K-a) of enantiomers and the chemical shift differences at saturation (Delta delta(c)) were calculated using H-1 NMR spectroscopy. Some problematic aspects concerning the application of NMR spectroscopy for the explanation of the chiral recognition mechanisms in separation techniques are also shortly discussed. The enantioseparation of a cationic chiral analyte using a cationic cyclodextrin derivative is reported for the first time. This result supports the possibility of enantioseparations in a selector-solute pair carrying the same net charge as recently reported for a negatively charged selector-solute pair.