1,1′-Dimethyl-4,4′-(2,4-di-1-naphthyl­cyclo­butane-1,3-di­yl)dipyridinium–(E)-1-methyl-4-[2-(1-naphth­yl)vin­yl]pyridinium–4-amino­benzene­sulfonate–water (0.25/1.50/2/2)

In the title compound, 1.5C(18)H(16)N(+)·0.25C(36)H(32)N(2) (2+)·2C(6)H(6)NO(3)S(−)·2H(2)O, the monocation exists in the E configuration with respect to the ethenyl C=C double bond and is almost planar, the dihedral angles between the pyridinium and the fused six-membered rings being 3.1 (7) and 3.8 (8)°. The dication lies about an inversion centre. In the crystal, the dication occupies almost the same site occupied by monocations at (x, y, z) and (−x, 1 − y, 1 − z). The anions and water mol­ecules are linked into a chain along the a axis by O—H⋯O and N—H⋯O hydrogen bonds. The structure is further stabilized by C—H⋯O hydrogen bonds and π–π inter­actions between pyridinium and benzene rings, with centroid–centroid distances in the range 3.516 (9)–3.553 (8) Å. The crystal is a twin with twin law, TWIN [Image: see text] 0 0 0 [Image: see text] 0 1 0 1. The monocation and dication are disordered with fractional site occupancy ratio of 0.75:0.25.