A squaramide cage capable of binding and extracting H2PO4− and HP2O73− in highly polar protic media

Abstract

A novel squaramide cage (2) binds H₂PO₄⁻ and HP₂O₇³⁻ with high selectivity and affinity in a highly polar protic solvent system. Receptor 2 is also able to extract these hydrophilic anions into a chloroform phase from water. The X-ray crystal structure demonstrated that compound 2 forms a complex with H₂PO₄⁻ with 1 : 1 stoichiometry in the solid state.