(E)-2-[4-(Dimethyl­amino)styr­yl]-1-methyl­quinolinium 4-methyl­benzene­sulfonate monohydrate

In the title compound, C(20)H(21)N(2) (+)·C(7)H(7)O(3)S(−)·H(2)O, the cation is essentially planar, as indicated by the dihedral angle of 2.79 (13)° between the quinolinium and the dimethylaminophenyl rings, and exists in the E configuration. The π-conjugated planes of the cation and the anion are inclined to each other at a dihedral angle of 66.95 (12)°. The cation is linked to the anion through C—H⋯O hydrogen bonds and the anion is further linked with the water mol­ecule by O—H⋯O hydrogen bonds, forming a three-mol­ecule unit. These units are arranged in a face-to-face manner into a ribbon-like structure along the b axis. The ribbons are stacked along the c axis. The crystal structure is further stabilized by C—H⋯π inter­actions involving the dimethyl­amino­phenyl and methyl­phenyl rings. A π–π inter­action with a centroid–centroid distance of 3.6074 (19) Å is also observed.