Tetra­aqua­bis­[1-(3-carb­oxy­phen­yl)-4,4′-bipyridin-1-ium-κN (1′)]zinc bis­(4,5-carb­oxy­benzene-1,2-dicarboxyl­ate) 2.5-hydrate

In the complex cation of the title compound, [Zn(C(17)H(13)N(2)O(2))(2)(H(2)O)(4)](C(10)H(4)O(8))(2)·2.5H(2)O, the Zn(II) atom, lying on an inversion center, is coordinated by two N atoms from two N-(3-carb­oxy­phen­yl)-4,4′-bipyridin-1-ium ligands and four water mol­ecules in a distorted octa­hedral geometry. The pyromellitate anion is double deprotonated. O—H⋯O and C—H⋯O hydrogen bonds connect the cations, anions and uncoordinated water mol­ecules into a three-dimensional supra­molecular network. One of the two lattice water molecules shows an occupancy of 0.25. An intra­molecular O—H⋯O hydrogen bond is present in the anion.