Binding properties of an abiotic receptor for complexing carboxylates of α-heterocyclic and α-keto acids

A receptor with high molecular recognition of carboxylates of α-heterocyclic and α-keto acids was prepared by introduction of hydroxamic function in a neutral anion binding receptor with a framework of bis-chromenylurea. The improved complexation of the host toward these guests resulted from a fifth hydrogen bond in the complexes between the OH donor of the host and the α-heteroatom acceptor of the guests.