Chiral effects of alkyl-substituted derivatives of N,O-bismethacryloyl ethanolamine on the performance of one monomer molecularly imprinted polymers (OMNiMIPs).

New monomers were synthesized and evaluated for their molecular imprinting performance by a recently discovered methodology referred to as one monomer molecularly imprinted polymers (OMNiMIPs). The structural design of the new monomers was based on a lead compound methacrylamidoethyl methacrylate (1) used for the synthesis of OMNiMIP1, and introduced alkyl groups of various sizes at the alpha-amino position of the lead compound. Enantioselectivity, determined by liquid chromatography, was used to compare the performance of the imprinted polymers. Methyl substitution provided crosslinker 5 (2-methacrylamidopropyl methacrylate), which upon imprint polymerization afforded OMNiMIP5 with approximately the same enantioselectivity (alpha = 3.8) as OMNiMP1 (alpha = 3.7) made with the lead compound (1). The other two monomers (6 and 7) with larger alkyl substitutions (isopropyl and sec-butyl respectively) resulted in OMNiMIPs with low selectivity values (alpha = 1.0 and 1.2 respectively). Last, a strong influence of diastereomeric complexes on OMNiMIP5 selectivity was determined, with L: /L: and D: /D: monomer/template pairs giving alpha values of 3.6-3.8, while L: /D: and D: /L: monomer/template pairs had alpha values of 2.3-2.4. There is no intrinsic enantioselectivity seen for the OMNiMIP5 control polymer made without template at all, giving an alpha value of 1.03.