In the title zwitterionic compound, C20H15N3O3S2, the 2-hy-droxy-naphthalene-1-carbaldehyde group A, the anilinic unit B and the 1,3-thia-zol-2(3H)-imine group C are each approximately planar with r.m.s. deviation of 0.0721, 0.0412 and 0.0125 Å, respectively. The dihedral angles between A/B, A/C and B/C are 24.70 (10), 79.97 (7) and 83.14 (6)°, respectively. There is an intra-molecular S(6) motif involving the imine N-H and the naphtho-late O atom. In the crystal, inversion-related mol-ecules form dimers as a result of N-H⋯N and N-H⋯O hydrogen bonds with R 2 (2)(8) and R 1 (2)(4) motifs, respectively. Weak π-π inter-actions between the benzene and naphthyl rings of inversion-related mol-ecules have ring centroid-centroid distances of 3.638 (2) and 4.041 (2) Å. A C-H⋯π inter-action occurs between the thia-zol ring and the benzene ring of an adjacent mol-ecule.
Keywords: C—H⋯π interactions; crystal structure; hydrogen bonding; sulfathiazole; zwitterionic compound; π–π interactions.