3-Hydr-oxy-N'-(2-hydroxy-benzyl-idene)benzohydrazide.

The title compound, C(14)H(12)N(2)O(3), was synthesized by the condensation of salicylaldehyde with 3-hydroxy-benzo-hydrazide. The dihedral angle between the two benzene rings is 12.4 (2)°. The 2-hydr-oxy group forms an intra-molecular O-H⋯N hydrogen bond with the imide N atom. Mol-ecules are linked through inter-molecular O-H⋯O and N-H⋯O hydrogen bonds into a two-dimensional polymeric structure parallel to the ab plane.

N'-(5-Bromo-2-hydr-oxy-3-methoxy-benzyl-idene)isonicotinohydrazide.

The title compound, C(14)H(12)BrN(3)O(3), was prepared by reaction of 5-bromo-3-methoxy-salicylaldehyde and isonicotinohydrazide in methanol. The mol-ecule is not planar and adopts a trans configuration with respect to the C=N bond. There is an intra-molecular O-H⋯N hydrogen bond in the mol-ecule. The dihedral angle between the benzene and pyridine rings is 12.2 (2)°. In the crystal structure, mol-ecules are linked through inter-molecular N-H⋯N hydrogen bonds, forming chains running along the c-axis direction.

(E)-N'-(2-Hydr-oxy-4-methoxy-benzyl-idene)isonicotinohydrazide monohydrate.

The title compound, C(14)H(13)N(3)O(3)·H(2)O, was prepared by the reaction of 4-methoxy-salicylaldehyde and isonicotinohydrazide in ethanol. The Schiff base mol-ecule is not planar and has an E configuration with respect to the methyl-idene unit. The dihedral angle between the benzene and pyridine rings is 36.8 (2)°. In the mol-ecule there is an intra-molecular O-H⋯N hydrogen bond involving the hydroxyl substituent and the N atom of the 2-hydr-oxy-4-methoxy-benzyl-idene unit. In the crystal, the mol-ecules are linked through inter-molecular O-H⋯O, O-H⋯N and N-H⋯O hydrogen bonds, forming layers parallel to the bc plane.