Development of uniform-sized, molecular-imprinted stationary phases for HPLC

摘要

Non-covalently molecular-imprinted, uniform-sized, polymer-based stationary phases are prepared by a two-step swelling technique using isomers of diaminonaphthalene or chiral amides derived from (S)-#alpha#-methylbenzylamine as template molecules. Methacrylic acid is an effective host molecule for the diaminonaphthalene templates and produces a molecular recognition ability almost equivalent to that of molecular-imprinted stationary phases prepared by traditional bulk polymerization. Unexpectedly, an imprinted, crosslinked, polymer-based stationary phase without this type of strong host functionality also showed moderate molecular recognition which suggests that the crosslinked polymer network itself can memorize the shape of template in some fashion. For chiral separations of the amide derivatives, the crosslinked polymer network also memorized the shape of the chiral template to provide chiral resolution. In addition, chiral host monomers with similar functionality as the chiral amide template were found to markedly enhance the molecular recognition. Furthe investigation suggests that this increase in chiral recognition is due to favorable structural interactions within specific recognition sites. Also, uniform-sized, polymer-based, HPLC stationary phases with multi-chiral selectors are prepared by a combination of molecular imprinting and in situ surface modification. Simple additivity of the chiral recognition abilities of the two types of chiral selectors is observed. Size exclusion chromatography reveals a possible causitive factor for the selectivity.