2-{(E)-1-[2-(4-Nitro-phen-yl)hydrazin-1-yl-idene]eth-yl}benzene-1,3-diol.

The title compound, C14H13N3O4, is close to planar, the dihedral angle between the terminal benzene rings being 5.80 (16)°; the nitro group is coplanar with the benzene ring to which it is bonded [O—N—C—C torsion angle = −177.3 (3)°]. The hy­droxy group forms an intra­molecular hydrogen bond with the imine N atom, and the conformation about the imine bond is E. In the crystal, layers in the (101) plane with an undulating topology are formed by O—H⋯O and N—H⋯O hydrogen bonds along with C—H⋯O inter­actions. Centrosymmetrically related layers are connected via π–π inter­actions [ring centroid–centroid distance = 3.5739 (19) A] into double layers.