(E)-1-Methyl-4-[2-(1-naphth-yl)vin-yl]pyridinium 4-chloro-benzene-sulfonate.

In the title compound, C(18)H(16)N(+)·C(6)H(4)ClO(3)S(-), the cation exists in an E configuration with respect to the central C=C bond. The naphthalene ring system is slightly bent, the dihedral angle between the two aromatic rings being 3.71 (14)°. The whole cation is twisted, the dihedral angles between the pyridinium and the two aromatic rings of the naphthalene ring system being 47.44 (14) and 50.81 (14)°. The pyridinium ring and the benzene ring of the anion are inclined to each other at a dihedral angle of 68.21 (13)°. In the crystal structure, the cations and anions are arranged alternately with the cations stacked in an anti-parallel manner along the c axis and the anions linked into chains along the same direction. The cations are linked to the anions by weak C-H⋯O inter-actions, forming a three-dimensional network. The crystal structure is further stabilized by C-H⋯π inter-actions and π-π contacts with centroid-centroid distances of 3.6374 (16) and 3.6733 (17) Å. A short Cl⋯O contact [3.108 (2) Å] is also present.