Selector-selectand interactions

Chankvetadze, B., and Blaschke, G. (1999). Selector-selectand interactions in chiral capillary electrophoresis. Electrophoresis 20, 2592—2604. 

In the early 1990s, several studies were published on the computation of selector-selectand interactions in chiral CE. This relates basically to the interactions between CDs and their chiral guests, which seem to be caused by the fact that CDs are rather rigid molecules of medium size and therefore calculations for these molecules are easier and faster and may be rather precise. In addition, many CDs are well studied by alternative techniques for structure elucidation. Among these, X-ray crystallographic data are of the highest interest. 

B Chankvetadze, M Fillet, N Burjanadze, D Bergenthal, C Bergander, H Luft-mann, J Crommen, G Blaschke. Enantioseparation of aminoglutethimide with cyclodextrins in capillary electrophoresis and studies of selector-selectand interactions using NMR spectroscopy and electrospray ionization mass spectrometry. Enantiomer 5 313-322, 2000. 

The high peak efficiency in CE allows one to observe (enantio)selective effects in selector-selectand interactions which are invisible by other (separation) techniques. 

Molecular Modeling of Selector-Selectand Interactions in Chiral CE. 138... 

A correlation between recognition and separation is simpler in pressure-driven techniques compared to electrically driven techniques. As stated in our previous papers [2, 3], in CE, in contrast to chromatographic techniques, a chiral separation is possible even in the absence of a chiral recognition in the classical meaning of this definition. On the other hand, a chiral recognition not always leads to chiral separation in CE. Thus, enantioseparation in CE may be a result of stereoselective selector-selectand interactions and achiral selector-selectand interactions but different mobility of the diastereomeric associates formed, or the combination of both. Independent of which of the aforementioned three mechanisms is involved in a particular case, selector-selectand interactions are an unavoidable part of any chiral CE separation [200]. 

Thus, as illustrated above, one-dimensional rotating frame nuclear Overhauser and exchange spectroscopy (ID-ROESY) experiments may provide a reasonable explanation for significant qualitative and quantitative differences observed in selector-selectand interactions related to chiral CE. This information becomes even... 

The major difference between the mathematical models of chiral CE and molecular modeling studies discussed in this chapter is that the former models describe the entire separation process and do not pay any significant attention to the selector-selectand interactions and/or to solvent molecules. In contrast, the molecular modeling techniques summarized in this section try to describe the selector-selectand interactions at the molecular level and do not estimate their role in the overall separation process. 

Chankvetadze B, Blaschke G (1999) Selector-selectand interactions in chiral capilltiry electrophoresis. Electrophoresis 20 2592-2604... 

Figures 2 and 3 show that macrocyclic glycopeptides are simple enough so that their molecules can be easily modeled by small computers. They also show the variety of possible selector-selectand interactions including all possible chemical interactions from the strongest charge-charge (coulombic) interaction to the delicate shape recognition interaction within the cavities of the polypeptide aglycon core of the selectors.

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