5-[2,4-Dihy­droxy-5-(5-hy­droxy-2,4,6-trioxo-3,5-di­hydro-1H-pyrimidin-5-yl)-3-meth­oxy­phen­yl]-5-hydroxy-3,5-di­hydro-1H-pyrimidine-2,4,6-trione penta­hydrate

The title compound, C15H12N4O11·5H2O, has a `propeller-like' structure. The two alloxan units have screw-boat conformations. Their mean planes are normal to the central aromatic ring with dihedral angles of 87.91 (7) and 88.27 (7)°, and they are inclined to one another by 40.86 (7)°. In the crystal, mol­ecules are linked via O—H⋯O and N—H⋯O hydrogen bonds, forming a three-dimensional framework. There are also C—H⋯O hydrogen bonds present within the framework.