Structure Reports Online

Volume 66, Part 3 (March 2010)

organic compounds

sj2719 scheme

Acta Cryst. (2010). E66, o580-o581 [ doi:10.1107/S1600536810004526 ]

4-[(2,4-Dihydroxybenzylidene)ammonio]benzenesulfonate trihydrate

C. S. Yeap, M. Hemamalini and H.-K. Fun

Abstract: The title Schiff base compound, C₁₃H₁₁NO₅S·3H₂O, formed from sulfanilic acid and 2,4-dihydroxybenzaldehyde, crystallized out as a zwitterion with the N atom protonated. The asymmetric unit consists of one 4-[(2,4-dihydroxybenzylidene)ammonio]benzenesulfonate and three water molecules. The zwitterion exists in an E configuration with respect to the central C=N double bond. The two benzene rings of the molecule are oriented at a dihedral angle of 27.33 (8)°. An intramolecular N-HO hydrogen bond stabilizes the molecular structure. In the crystal, the zwitterions are linked into chains along [101] by intermolecular O-HO and N-HO hydrogen bonds. The three water molecules link these chains into a three-dimensional framework by additional intermolecular O-HO hydrogen bonds. A [pi] [pi] interaction [3.5485 (9) Å] further stabilizes the crystal structure.