Rate-enhancement of hydrolysis of long-chain amino acid ester by cross-linked polymers imprinted with a transition-state analogue: evaluation of imprinting effect in kinetic analysis

Acceleration property of a cross-linked polymer catalyst for the hydrolysis of N-dodecanoyl leucine-p-nitrophenyl ester is attributed to the molecularly imprinting of phenyl-1-undecylcarbonylamino-3-methylbutyl phosphonate as the template of transition-state analogue (TSA) and 4-[(3ʹ-methacryloylamino)ethyl]imidazole as the binding site of the polymer catalyst. Equimolar complex of the template of the TSA and the binding site of imidazole-containing monomer through the electrostatic interaction and hydrophobic effect was confirmed by 1H NMR measurements and the complex was copolymerized with hydrophobic styrene monomer and 10% divinylbenzene cross-linker. A control polymer without the template, but with the cross-linker, was also prepared. After removal of the template, imidazole-containing imprinted polymer gave a ca. two-fold rate-enhancement in comparison to the non-imprinted polymer.