Synthesis And Characterization Of S-(-)-α-Phenylethylamine Molecularly Imprinted Polymers

Molecularly imprinted technique ( MIT), also called Molecular template technique( MTT), is a new technique for synthesis of macromolecular materials with molecular recognition capability. they have been extensively used in chromatographic separation ,enzymatic mimic, solid-phase extraction, chemosensors and other relevant fields. For enantioselective separation, MIT has its advantages compared to enzyme and some other approaches,because MIP was similar to enzyme in specificity and selectivity even under extreme conditions, could be synthesized readily, and may be reused through simple washing of the template immobilized polymer. The application of MIT to enantioselective separation became one of the research attractions.The principle, synthetic method ,application of molecular imprinting technology and development were reviewed in this paper. molecular imprinted polymers were prepared by two methods, which include bulk polymerization and suspension polymerization. In the polymerization procedure,S-(-)-α-phenyl ethylamine was used as target template molecules,methacrylic acid(MAA) was selected as functional monomers, ethylene glycol dimethacrylate(EDMA) or divinylbenzene(DVB) as crosslinker, azobisisobutyronitrile or benzophenone was used as irritator.The effect of different synthetic method and type of cross-linking monomers, as well as degree of cross-linking on the binding capacity of polymers, has been studied by UV spectroscopy ,equilibrium binding assay, and Scatchard model .The results were showed as follows: the properties of polymers prepared by suspension polymerization were better than those prepared by bulk polymerization,and the difference in adsorption varied from 10% to 30%; divinylbenzene is a better choice as the cross-linker compared with ethylene glycol dimethacrylate, yielding polymers with higher analyte binding,and the binding capacity of the former for template is about twice as much as the latter's ; and binding capacity of polymers decrease with the degree of cross-linking,while recognition properties of polymers increase with the degree of cross-linking.The separate factor(α) between S-(-)-α-phenyl ethylamine and acetophenone(the substrate analog) for all polymers was above one,and the maximum ofαwas 2.86.This indicated that all polymers had good selection. Molecularly imprinted polymers of S-(-)-α-phenyl ethylamine were prepared to use as chiral stationary phases in thin-layer chromatography (TLC),and the results reveal that TLC based on MIP could succeed the direct separation of enantiomer ofα-phenyl ethylamine as a method of separation,R=1.93.