title: Bis(5,6-dicarboxy-benzimidazolium) sulfate monohydrate.
abstract: In the title compound, 2C(9)H(7)N(2)O(4) (+)·SO(4) (2-)·H(2)O, the sulfate S atom and the water O atom reside on a crystallographic twofold axis. In the crystal, the component species are linked by N-H⋯O, O-H⋯O and C-H⋯O hydrogen bonds, forming a three-dimensional network structure. An intramol-ecular O-H⋯O link is seen in the cation.
authors.affiliation: College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124, People's Republic of China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Cui
authors.forename: Qian
authors.initials: Q
authors.lastname: Gao
authors.forename: Chao-Yan
authors.initials: CY
authors.lastname: Zhang
authors.forename: Ya-Bo
authors.initials: YB
authors.lastname: Xie