1H Nuclear magnetic resonance study of the molecular imprinting of (−)-nicotine: template self-association, a molecular basis for cooperative ligand binding

In the present study, the interactions of components in a (−)-nicotine molecular imprinting polymerization mixture have been studied by 1H NMR spectroscopy. The dissociation constants for complexation of template by a functional monomer analogue, acetic acid, have been determined. Nicotine was shown to self-associate at concentrations comparable to those used in previous molecular imprinting studies (app Kdiss=0.082 M in CDCl3 at 298 K). The extent of self-association was enhanced by the presence of acetic acid. Previous studies on (−)-nicotine–imprinted methacrylic acid–ethylene dimethacrylate co-polymers suggested the involvement of recognition sites for template–template complexes. Collectively these results provide the first direct evidence for the presence of template–template complexes, and support the previously hypothesized basis for cooperative ligand recognition events in this polymer system.