2,2'-[2,4-Bis(naphthalen-1-yl)cyclo-butane-1,3-di-yl]bis-(1-methyl-pyridinium) bis-(4-chloro-benzene-sulfonate): thermal-induced [2 + 2] cyclo-addition reaction of a heterostilbene.

The asymmetric unit of the title salt, C36H32N2 (2+)·2C6H4ClO3S(-), consists of one anion and one half-cation, the other half being generated by inversion symmetry. The dihedral angle between the pyridinium ring and the napthalene ring system in the asymmetric unit is 42.86 (6)°. In the crystal, cations and anions are linked by weak C-H⋯O inter-actions into chains along [010]. Adjacent chains are further arranged in an anti-parallel manner into sheets parallel to the bc plane. π-π inter-actions are observed involving the cations, with centroid-centroid distances of 3.7664 (8) and 3.8553 (8) Å.