N'-[(E)-2-Hy-droxy-3,5-diiodo-benzyl-idene]pyridine-3-carbohydrazide.

In the title compound, C(13)H(9)I(2)N(3)O(2), the dihedral angle between the two aromatic rings is 10.5 (2)°. The mol-ecule displays a trans configuration with respect to the C=N bond. An intra-molecular O-H⋯N hydrogen bond occurs. The crystal packing is stabilized by N-H⋯O and C-H⋯O hydrogen bonds.

N'-[(E)-2-Hy-droxy-3,5-diiodo-benzyl-idene]cyclo-hexa-ne-1-carbohydrazide.

In the title compound, C(14)H(10)I(2)N(2)O(2), the two aromatic rings are inclined at a dihedral angle of 16.72 (33)°. The mol-ecular structure is stabilized by an intra-molecular O-H⋯N hydrogen bond. In the crystal, inter-molecular N-H⋯O inter-actions link the mol-ecules into chains running along the c axis. C-H⋯O inter-actions also occur. The crystal used for the structure determination was a non-merohedral twin with a domain ratio of 0.972 (2):0.028 (2).

N'-[(1E)-3-Bromo-5-chloro-2-hy-droxy-benzyl-idene]-4-tert-butyl-benzo-hydrazide ethanol monosolvate.

In the title compound, C(18)H(18)BrClN(2)O(2)·C(2)H(6)O, the hy-droxy group forms an intra-molecular O-H⋯N hydrogen bond, which influences the conformation of the Shiff base mol-ecule, where the two aromatic rings form a dihedral angle of 21.67 (8)°. Inter-molecular N-H⋯O and O-H⋯O hydrogen bonds link two Shiff base mol-ecules and two solvent mol-ecules into a centrosymmetric heterotetra-mer. Weak inter-molecular C-H⋯O inter-actions link further tetra-mers related by translation along the a axis into chains.