title: Tetra-aqua-bis-[1-(3-carb-oxy-phen-yl)-4,4'-bipyridin-1-ium-κN]zinc bis-(4,5-carb-oxy-benzene-1,2-dicarboxyl-ate) 2.5-hydrate.
abstract: 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-carb-oxy-phen-yl)-4,4'-bipyridin-1-ium ligands and four water mol-ecules in a distorted octa-hedral geometry. The pyromellitate anion is double deprotonated. O-H⋯O and C-H⋯O hydrogen bonds connect the cations, anions and uncoordinated water mol-ecules into a three-dimensional supra-molecular network. One of the two lattice water molecules shows an occupancy of 0.25. An intra-molecular O-H⋯O hydrogen bond is present in the anion.
authors.affiliation: Key Lab for Fuel Cell Technology of Guangdong Province, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou,  People's Republic of China.
authors.forename: Jie
authors.initials: J
authors.lastname: Zhang
authors.forename: Yi
authors.initials: Y
authors.lastname: Tan
authors.forename: Zhiyong
authors.initials: Z
authors.lastname: Fu