Molecularly imprinted polymers enantiomeric resolution

O Shannessy, D.J. Andersson, L.I. Mosbach, K. Molecular recognition in synthetic polymers. Enantiomeric resolution of amide derivatives of amino acids on molecularly imprinted polymers. J. Mol. Recognit. 1989, 2, 1-5. 

Andersson LI, Miyabayashi A, O Shannessy DJ et al. Enantiomeric resolution of amino acid derivatives on molecularly imprinted polymers as monitored by potentiometric measurements. J Chromatogr 1990 516 323-331. 

O Shannessy, D.Y., Ekberg, B., Andersson, L.I. and Mosbach, K., Recent advances in the preparation and use of molecularly imprinted polymers for enantiomeric resolution of amino acid derivatives, J. Chromatogr., 470, 391-399, 1989. 

The CSPs prepared by the molecular imprint technique have also been used for chiral resolution by CEC [98-100]. Lin et al. [91] synthesized L-aromatic amino acid-imprinted polymers using azobisnitriles with either photoinitiators or thermal initiators at temperatures ranging from 4°C to 60° C. Methacrylic acid (MAA) was used as the functional monomer and ethylene glycol dimethacrylate (EDMA) was used as the cross-linker. The resulting polymers were ground and sieved to a particle size less than 10 pm, filled into the capillary columns, and used for enantiomeric separations of some amino acids at different temperatures. The relationships of separation factor and column temperatures were demonstrated to be linear between the logarithm of the separation factors and the inverse of the absolute temperature (Fig. 24). The authors also compared the obtained chiral resolution with the chiral resolution achieved by HPLC and reported the best resolution on CEC. The chromatograms of the chiral resolution of dl-... 

According to Dalgliesh [2], three active positions on the selector must interact simultaneously with the active positions of the enantiomer to reveal differences between optical antipodes. This is a sufficient condition for resolution to occur, but it is not necessary. Chiral discrimination may happen as a result of hydrogen-bonding and steric interactions, making only one attractive force necessary in this type of chromatography. Moreover, the creation of specific chiral cavities in a polymer network (as in molecular imprinting techniques) could make it possible to base enantiomeric separations entirely on steric fit. 

As Table 2-3 shows, imprinted polymers have been mainly used as separation media (mostly in chromatography). Of special interest is the enantiomeric resolution of race-mates. Further applications are as immunosorbents and chemosensors. The cavities in the imprinted polymers have also been used as microreactors for selective reactions and, more interestingly, as the active sites of catalytically active polymers. In 1998 nearly 100 papers appeared in the literature on molecular imprinting, together with one book [114] another book is imminent [115]. 

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