2-Hydroxy-5-(2-hydroxy-3-methoxy-benzylideneamino)benzoic acid

The title compound, C15H13NO5, was obtained by the condensation of o-vanillin with 5-aminosalicylic acid. The molecule is nonplanar with a dihedral angle of 13.2 (2)degrees between the two aromatic rings. The carboxyl and methoxy groups are almost coplanar with the attached rings. The molecular structure is stabilized by O - H center dot center dot center dot N and O - H center dot center dot center dot O hydrogen bonds. Intermolecular O - H center dot center dot center dot O hydrogen bonds link the molecules into a chain along the c axis, and adjacent chains are crosslinked by C - H center dot center dot center dot O hydrogen bonds and pi - pi stacking interactions involving the two benzene rings [centroid-centroid distance = 3.685 (3) angstrom ].