Crystal structure of 1,3-bis­(1,3-dioxoisoindolin-1-yl)urea dihydrate: a urea-based anion receptor

The whole mol­ecule of the title compound, C(17)H(10)N(4)O(5)·2H(2)O, is generated by twofold rotation symmetry and it crystallized as a dihydrate. The planes of the phthalimide moieties and the urea unit are almost normal to one another, with a dihedral angle of 78.62 (9)°. In the crystal, mol­ecules are linked by N—H⋯O and O—H⋯O hydrogen bonds, forming a three-dimensional framework structure. The crystal packing also features C—H⋯O hydrogen bonds and slipped parallel π–π inter­actions [centroid–centroid distance = 3.6746 (15) Å] involving the benzene rings of neighbouring phthalimide moieties.