The centrosymmetric title compound, {(C4H12N2)- [Zn(C14H6N2O8)2]4H2O}n or {(pipzH2)[Zn(py-2,3-dc)2]- 4H2O}n, where py-2,3-dcH2 is pyridine-2,3-dicarboxylic acid and pipz is piperazine, was obtained by the reaction of zinc(II) nitrate tetrahydrate with (pipzH2)(py-2,3-dc) as a protontransfer compound in aqueous solution. Each ZnII (site symmetry 1) is coordinated in a distorted octahedral geometry by four O atoms and two N atoms from two bidentate (py-2,3- dc)2 ligands, which also act as bridging ligands between ZnII atoms. The four donor atoms of the two coplanar (py-2,3-dc)2 anions form a square-planar arrangement around the ZnII centre. In the crystal structure, extensive O—H O, N— H O and C—H O hydrogen bonds, as well as ion pairing and – stacking [with a distance of 3.8693 (8) A ˚ between two aromatic rings] between different fragments, play an important role in the stabilization of the supramolecular structure.
