Stabilisation of alkylcarbamate anions using neutral hydrogen bond donors

The interactions of a series of urea-based anion receptors and alkylcarbamate species formed by the reaction of carbon dioxide with primary amines have been investigated by 1H NMR. Significant downfield shifts in the NH proton signals of the receptors in the presence of the alkylcarbamates were observed, consistent with classical host:anion hydrogen-bonding. This observation demonstrates that neutral hydrogen bond donor receptors can compete with ammonium cations to bind carbamates in DMSO-d6 solution.