Carboxylate complexation by 1,1'-(1,2-phenylene)bis(3-phenylurea) in solution and the solid state.

A simple bis-urea containing anion receptor, synthesised from ortho-phenylenediamine, has been shown to have excellent selectivity for carboxylates in solution, with a crystal structure elucidation of the benzoate complex showing four hydrogen bonds between the receptor and anion in the solid state.