catena-Poly[zinc(II)-μ3-{hydrogen [1-hydr­oxy-2-(3-pyridinio)ethane-1,1-di­yl]diphospho­nato}]

In the polymeric title compound, [Zn(C7H9NO7P2)]n, the zinc(II) centre displays a tetra­hedral coordination geometry provided by four O atoms from three different phospho­nate groups. The crystal structure consists of ladder chains parallel to the b axis built up from vertex-sharing of ZnO4 and PO3C tetra­hedra. The chains are linked by strong intra- and inter­chain O—H⋯O and N—H⋯O hydrogen bonds, forming a three-dimensional supra­molecular assembly.