Enhanced Enantioselectivity of Molecularly Imprinted Polymers Formulated with Novel Cross-Linking Monomers

To enhance the performance of molecularly imprinted polymers (MIPs), three new cross-linking monomers were designed, synthesized, and evaluated as matrix elements for molecularly imprinted polymers. Hybrid cross-linking monomers incorporating methacrylamide/methacrylate (NOBE), vinyl ketone/methacrylamide (NAG), and vinyl ketone/methacrylate (MVK) polymerizable groups, were synthesized and used to prepare MIPs and compared to a traditional MIP formulated with EGDMA. The resulting macroporous MIPs were evaluated by HPLC for their ability to separate the enantiomers of a chiral template. The MIP formulated with the cross-linking monomer NAG showed the highest enantioselectivity and complete baseline resolution for a racemic mixture of the template. Enhancement in selectivity in this MIP may be attributed to the presence of the amide group which can promote hydrogen bonding via favorable 1,3 donor−acceptor interactions with the template, the morphology of the polymeric material obtained due to differences in reactivity between the polymerizable groups and improved resolution in cavity formation as a consequence of shorter cross-linker size.