(E)-1-[2-(2-Cyanophenyl)diazen-2-ium-1-yl] naphthalen-2-olate

There are two independent zwitterion molecules (A and B) in the asymmetric unit of the title compound, C17H11N3O, which belongs to the family of azo dyes. The dihedral angle between the benzene ring and the naphthalene ring system is 6.99 (6)degrees in molecule A and 4.38 (6)degrees in molecule B. The azo group adopts an E conformation with respect to the -N = N-bond and each of the independent molecules has an intramolecular N-H center dot center dot center dot O hydrogen bond. In the crystal, molecules are linked by C-H center dot center dot center dot O and C-H center dot center dot center dot N hydrogen bonds, forming ribbons propagating along [(1) over tilde 10]. The ribbons are linked via pi-pi interactions involving the benzene and naphthalene rings of inversion-related A and inversion-related B molecules, forming a three-dimensional structure. The most significant centroid-centroid distances vary from 3.6599 (6) to 3.7538 (9) angstrom.