Carbohydrate-based receptors with multiple thiourea binding sites.: Multipoint hydrogen bond recognition of dicarboxylates and monosaccharides

The binding properties of multitopic sugar thiourea receptors toward dicarboxylate and monosaccharide guests have been examined taking glutarate and octyl P-D-glucopyranoside as model ligands. For the anionic hydrogen bond acceptor, both the complex stoichiometry and the association constants (K-as) were found to be strongly dependent on the relative disposition of recognition elements in the host. In contrast, for the glucoside guest a 1:1 stoichiometry was observed in all cases, the K-as values being largely independent of the unbound state provided that geometrically equivalent supramolecular topologies can be achieved.