Bis(μ-3-carb­oxy-2-hy­droxy­propane-1,2-dicarboxyl­ato)bis(diaquazinc)–1,2-bis­(pyridin-4-yl)ethene–water (1/1/2)

The asymmetric unit of the title compound, [Zn(2)(C(6)H(6)O(7))(2)(H(2)O)(4)]·C(12)H(10)N(2)·2H(2)O, comprises half of a centrosymmetric complex dimer, half of a 1,2-bis­(pyridin-4-yl)ethene mol­ecule, which lies across an inversion centre, and one lattice water mol­ecule. Carboxyl­ate groups of two dianionic citrate ligands bridge two Zn(II) ions to give the cyclic dimer, with each Zn(II) ion coordinated by four O atoms from the chelating citrate ligand (one hy­droxy and three carboxyl­ate, with one bridging) and two water O atoms, forming a distorted octa­hedral environment [Zn—O = 2.040 (3)–2.244 (3) Å]. In the crystal, O—H⋯O and O—H⋯N hydrogen bonds involving hy­droxy groups and both coordinating and lattice water mol­ecules link the dimers to give a three-dimensional framework structure.