Glazer (1986). Experimental Crystal data

R factor = 0.040; wR factor = 0.110; data-to-parameter ratio = 32.6. In the title compound, C16H15N2 +C6H4ClO3S, the cation exists in an E configuration with respect to the central C C bond and is approximately planar, with a dihedral angle of 2.95 (5) between the pyridinium and indole rings. The mean plane of the -conjugated system of the cation and the benzene ring of the anion are inclined to each other at a dihedral angle of 69.65 (4). In the crystal packing, the cations are stacked in an antiparallel manner along the a axis, resulting in a – interaction with a centroid–centroid distance of 3.5889 (7) Å. The anions are linked into a chain along the a axis by weak C—H O interactions. The cations are linked with the anions into a three-dimensional network by N—H O hydrogen bonds and weak C—H O inter-actions. There are also short O Cl [3.1272 (10) Å] and C O [3.1432 (14)–3.3753 (14) Å] contacts. The crystal structure is further stabilized by C—H interactions. Related literature For bond-length data, see: Allen et al. (1987). For background to non-linear optical materials research, see: Ogawa et al