4-Dimethyl-amino-N'-(2-hy-droxy-3,5-diiodo-benzyl-idene)benzohydrazide.

The title mol-ecule, C(16)H(15)I(2)N(3)O(2), adopts an E configuration about the C=N bond. The dihedral angle between the two benzene rings is 6.4 (2)°. An intra-molecular O-H⋯N hydrogen bond occurs. In the crystal, mol-ecules are linked through inter-molecular N-H⋯O hydrogen bonds, forming chains propagating in the c-axis direction.

(E)-N'-(3-Hy-droxy-benzyl-idene)-3-nitro-benzohydrazide.

The title compound, C(14)H(11)N(3)O(4), was prepared by the reaction of 3-nitro-benzohydrazide with 3-hy-droxy-benzalde-hyde. The mol-ecule adopts an E configuration about the C=N bond. The dihedral angle between the two benzene rings is 32.3 (2)°. In the crystal, the mol-ecules are linked through inter-molecular N-H⋯O, O-H⋯N, and O-H⋯O hydrogen bonds, forming chains in the a-axis direction.

N'-(4-Hy-droxy-benzyl-idene)-4-nitro-benzohydrazide.

The title compound, C(14)H(11)N(3)O(4), was prepared by the reaction of 4-nitro-benzohydrazide with 4-hy-droxy-benz-alde-hyde. The whole mol-ecule of the compound is approximately planar, with a mean deviation from the least-squares plane through all the non-H atoms of 0.050 (2) Å; the dihedral angle between the two benzene rings is 2.0 (2)°. In the crystal, the benzohydrazide mol-ecules are linked through inter-molecular O-H⋯O and N-H⋯O hydrogen bonds, forming layers in the bc plane.

N'-(3-Hy-droxy-benzyl-idene)-4-nitro-benzohydrazide.

The title mol-ecule, C(14)H(11)N(3)O(4), is approximately planar, with an inter-planar angle between the two benzene rings of 5.8 (2)°. In the crystal, four mol-ecules are linked by an R(4) (4)(12) motif with pairs of strong O-H⋯O and N-H⋯O hydrogen bonds. The motif is situated about the crystallographic centres of symmetry and it is composed of two pairs of parallel mol-ecules. This quadruplet of mol-ecules is further extended by symmetry-equivalent hydrogen bonds to form layers parallel to the (10) plane. In addition to the hydrogen bonds, there is also a weak π-π inter-action between the benzene rings.

(E)-N'-(2,4-Dichloro-benzyl-idene)-3-nitro-benzohydrazide.

The title compound, C(14)H(9)Cl(2)N(3)O(3), was prepared by the reaction of 3-nitro-benzohydrazide with 2,4-dichloro-benzalde-hyde. The mol-ecule adopts an E configuration about the C=N bond. The dihedral angle between the two benzene rings is 4.6 (2)°. In the crystal, the hydrazone mol-ecules are linked through inter-molecular N-H⋯O hydrogen bonds, forming chains along the c axis.