Date Published: March 01, 2012
Publisher: International Union of Crystallography
Author(s): Jin-Hang Li, Fu-Yue Dong, Fang Cai, Xiao-Feng Yuan, Ren-Wang Jiang.
The asymmetric unit of the title compound, C7H6O5·0.25H2O, contains two molecules of 2,3,4-trihydroxybenzoic acid, with similar conformations, and one water molecule which lies on a twofold rotation axis. Both acid molecules are essentially planar [maximum r.m.s deviations = 0.0324 (2) and 0.0542 (3) Å for the two acid molecules]. The molecular conformations are stabilized by intramolecular O(phenol)—H⋯O(carboxyl/phenol) interactions. A cyclic intermolecular association is formed between the two acid and one water molecule [graph set R33(12)] involving O—H⋯O hydrogen bonds. The two acid molecules are further linked through a cyclic R22(8) carboxylic acid hydrogen-bonding association, which together with intermolecular O—H⋯O hydrogen-bonding interactions involving the phenol groups and the water molecule, and weak π–π interactions [minimum ring centroid separation = 3.731 (3) Å], give a three-dimensional network.
For the natural distribution of 2,3,4-trihydroxybenzoic acid, see: Zhai et al. (2010 ▶); Xu & Chang (2010 ▶). For its antioxidant and antibacterial activities, see: Kodama et al. (2007 ▶); Friedman et al. (2003 ▶). For the inhibition of xanthine oxidase, see: Chang et al. (1995 ▶). For the crystal structure of the dihydrate pseudopolymorph, see: Prior & Sharp (2010 ▶). For π–π interactions in gallic acid pyridine monosolvate and in natural flavonoids, see: Dong et al. (2011 ▶); Jiang et al. (2009 ▶, 2002 ▶). For graph-set analysis, see: Etter et al. (1990 ▶); Bernstein et al. (1995 ▶).