Aqua­(4-hydroxy­pyridine-2,6-dicarboxyl­ato)(1,10-phenanothroline)copper(II) 4.5-hydrate

The title compound, [Cu(C(7)H(3)NO(5))(C(12)H(8)N(2))(H(2)O)]·4.5H(2)O or [Cu(hypydc)(phen)(H(2)O)]·4.5H(2)O (phen is 1,10-phenanthroline and hypydcH(2) is 4-hydroxy­pyridine-2,6-dicarboxylic acid), was obtained by the reaction of copper(II) nitrate hexa­hydrate with the proton-transfer compound (phenH)(2)(hypydc) in aqueous solution. Both the cationic and the anionic fragments of the proton-transfer compound are involved in complexation. Each Cu(II) atom has a distorted octa­hedral geometry. It is hexa­coordinated by three O atoms and three N atoms, from one phen fragment (as bidentate ligand), one (hypydc)(2−) unit (as tridentate ligand) and a water mol­ecule. In the crystal structure, O—H⋯O and C—H⋯O hydrogen bonds, and π–π stacking inter­actions [centroid-to-centroid distance 3.5642 (11) Å] between the phen ring systems, contribute to the formation of a three-dimensional supra­molecular structure.