1-[(E)-2-(2-Hy­droxy-5-methyl­phen­yl)diazen-2-ium-1-yl]naphthalen-2-olate

The title zwitterion, C(17)H(14)N(2)O(2), crystallizes with two independent mol­ecules in the asymmetric unit, both of which are approximately planar, the dihedral angles between the benzene ring and the naphthalene ring system being 4.39 (12)° in one mol­ecule and 5.83 (12)° in the other, and show an E conformation with respect to the azo double bond. An intra­molecular N—H⋯O hydrogen bond in each molecule helps to establish their near planar conformation. In the crystal, mol­ecules are linked through O—H⋯O hydrogen bonds into infinite chains running along the a-axis direction. In addition, the chains are stacked along the b axis via π–π inter­actions between the benzene and the naphthalene rings of adjacent mol­ecules, the centroid–centroid distances being 3.722 (3) and 3.823 (4) Å.