(E)-1-(4-Fluoro­phen­yl)-2-(2-oxidonaphthalen-1-yl)diazen-1-ium

In the title zwitterion, C16H11FN2O, which belongs to the family of azo dyes, the dihedral angle between the benzene ring and the naphthalene ring system is 15.33 (7)° and an intra­molecular N—H⋯O hydrogen bond closes an S(6) ring. In the crystal, inversion dimers linked by weak C—H⋯O hydrogen bonds generate R22(16) loops. Aromatic π–π stacking [centroid–centroid distance = 3.585 (11) A] is also observed.