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Electrophoresis, Vol.41, No.12, 1023-1030, 2020
Separation of terbutaline enantiomers in capillary electrophoresis with neutral cyclodextrin-type chiral selectors and investigation of the structure of selector-selectand complexes using nuclear magnetic resonance spectroscopy
The major goal of this study was to determine the affinity pattern of the terbutaline (TB) enantiomers toward alpha-, beta-, gamma-, and heptakis(2,3-di-O-acetyl)-beta-cyclodextrins and using NMR spectroscopy for the understanding of the fine mechanisms of interaction between the cyclodextrins (CD) and TB enantiomers. It was shown once again that CE in combination with NMR spectroscopy represents a sensitive tool to study the affinity patterns and structure of CD complexes with chiral guests. Opposite affinity patterns of TB enantiomers toward native alpha- and beta-CDs were associated with significant differences between the structure of the related complexes in solution. In particular, the complex between TB enantiomers and alpha-CD was of the external type, whereas an inclusion complex was formed between TB enantiomers and beta-CD. One of the possible structures of the complex between TB and heptakis(2,3-di-O-acetyl)-beta-CD (HDA-beta-CD) was quite similar to that of TB and beta-CD, although the chiral recognition pattern and enantioselectivity of TB complexation with these two CDs were very different.
Keywords:Cyclodextrins;enantiomer migration order;selector-selectand complexes;separation of enantiomers;terbutaline