2-[(E)-2-(4-Hy-droxy-3-meth-oxy-phen-yl)ethen-yl]-1-methylpyridinium 4-bromo-benzene-sulfonate monohydrate

The title salt crystallized as the monohydrate C15H16NO2 (+)·C6H4BrSO3 (-)·H2O. The cation exists in an E conformation with respect to the ethynyl bond and is essentially planar, with a dihedral angle of 6.52 (14)° between the pyridinium and the benzene rings. The hy-droxy and meth-oxy substituents are coplanar with the benzene ring to which they are attached, with an r.m.s. deviation of 0.0116 (3) Å for the nine non-H atoms [Cmeth-yl-O-C-C torsion angle = -0.8 (4)°]. In the crystal, the cations and anions are stacked by π-π inter-actions, with centroid-centroid distances of 3.7818 (19) and 3.9004 (17) Å. The cations, anions and water mol-ecules are linked by O-H⋯O hydrogen bonds and weak C-H⋯O inter-actions, forming a three-dimensional network.