title: 8,10-Diiodo-2,6-dioxo-4λ-ioda-3,5-dioxatricyclo-[5.3.1.0]undeca-1(11),7,9-triene-9-carb-oxy-lic acid.
abstract: In the title compound, C(9)HI(3)O(6)·2H(2)O, the mol-ecule is located on a twofold axis that gives rise to disorder of the carboxyl group. This disorder is correlated with the disorder of one of the H atoms of the water mol-ecule. The carboxyl group is twisted relative to the attached benzene ring by 75.1 (4)°. The intra-molecular I⋯O distance is 2.112 (6) Å. Mol-ecules are linked via O-H⋯O hydrogen bonding, C-I⋯O halogen bonding, with I⋯O distances in the range 3.156 (5)-3.274 (6) Å, and dipolar C=O⋯C=O inter-actions between the carboxyl and carboxyl-ate groups, with an O⋯C distance of 2.944 (10) Å.
authors.affiliation: Key Laboratory for Special Functional Aggregated Materials of the Education Ministry, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100,  People's Republic of China.
authors.forename: Daopeng
authors.initials: D
authors.lastname: Sheng
authors.forename: Lu
authors.initials: L
authors.lastname: Han
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhang
authors.forename: Yanzhao
authors.initials: Y
authors.lastname: Yang