Experimental Crystal data

disorder in main residue; R factor = 0.075; wR factor = 0.176; data-to-parameter ratio = 16.0. The asymmetric unit of the title salt, C16H19N2 C6H4NO5S consists of two cations and two anions. The crystal structure is stabilized by – interactions between the pyridyl and phenyl rings of the cations, with a centroid–centroid distance of 3.7323 (6) Å. Related literature The title compound was synthesized as part of our continuing research on the non-linear optical properties of DAS (4-N,N-dimethylamino-40-N0-methylstilbazolium) derivatives. For the synthesis, see: Okada et al. (1990). For background to non-linear optical materials, see: Yang et al. (2005); Kumar et al. (2009); Kwon et al. (2010). For the effects of different substituents of benzene sulfonate on its non-linear optica