(E)-2-[4-(Dimethyl-amino)styr-yl]-1-methyl-quinolinium iodide sesquihydrate

In the title compound, C(20)H(21)N(2) (+.)I(-)·1.5H(2)O, the cation exists in the E configuration and is not planar. The dihedral angle between the quinolinium and dimethyl-amino-phenyl rings is 9.26 (6)°. The O atom of one of the solvent water mol-ecules lies on a twofold rotation axis. In the crystal structure, the cations form one-dimensional zigzag chains along the [001] direction. The cations are linked to water mol-ecules and iodide ions through weak C-H⋯O and C-H⋯I inter-actions, respectively. Water mol-ecules and iodide ions form O-H⋯O and O-H⋯I hydrogen bonds, which stabilize the crystal structure. A C-H⋯π inter-action is also present.