2-[(E)-2-(4-Hy­droxy-3-meth­oxy­phen­yl)ethen­yl]-1-methylpyridinium 4-bromo­benzene­sulfonate monohydrate

The title salt crystallized as the monohydrate C(15)H(16)NO(2) (+)·C(6)H(4)BrSO(3) (−)·H(2)O. 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 hy­droxy and meth­oxy 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 [C(meth­yl)—O—C—C torsion angle = −0.8 (4)°]. In the crystal, the cations and anions are stacked by π–π inter­actions, with centroid–centroid distances of 3.7818 (19) and 3.9004 (17) Å. The cations, anions and water mol­ecules are linked by O—H⋯O hydrogen bonds and weak C—H⋯O inter­actions, forming a three-dimensional network.