Imprinted Polymers Prepared with Stoichiometric Template−Monomer Complexes:  Efficient Binding of Ampicillin from Aqueous Solutions

Two new functional monomers for molecular imprinting, 5-(4‘ ‘‘-vinyl)benzyloxy-1,3-bis[2‘-(3‘ ‘,3‘ ‘,4‘ ‘,4‘ ‘-tetramethyl-2‘ ‘,5‘ ‘-dioxaborolanyl)phenylcarbomoyl]benzene (3) and 2-(4-vinylphenyloxy)-3,5,6-trichlorobenzoquinone (4), designed to interact with carboxylate and amino groups, respectively, were synthesized. NMR titrations confirmed the interactions of 3 with tertabutylammonium acetate and ampicillin carboxylate in d 6-DMSO and of 4 with the free amino group of ampicillin in the same solvent. Polymers were prepared, using DMSO or THF as porogen, imprinted with ampicillin carboxylate using 3 and 4 present in the polymerization mixture in only stoichiometric amounts. The polymer made in DMSO was shown to bind ampicillin from aqueous buffer at pH 8.0 with two populations of binding sites, the first characterized by K d = (3.0 ± 0.3) × l0-5 mol/L at a capacity of 5.8 ± 0.3 μmol/g and the second by K d = (9.6 ± 1.1) × l0-4 mol/L and 48 ± 3.4 μmol/g.