2-[((E)-2-{2-[(E)-2-Hy­droxy­benzyl­idene]hydrazinecarbon­yl}hydrazinyl­idene)meth­yl]phenol

The mol­ecule of the title compound, C15H14N4O3, is completed by the application of crystallographic twofold symmetry, with the carbonyl group lying on the rotation axis. The mol­ecule is close to planar: the greatest deviation of a torsion angle from 0° is 7.3 (2)° about the bond linking the phenol ring to the rest of the mol­ecule. An intra­molecular O—H⋯N(imine) hydrogen bond is formed in each half of the mol­ecule. The carbonyl O atom is anti with respect to the amine H atoms and this allows for the formation of N—H⋯O(hydrox­yl) hydrogen bonds in the crystal, which results in supra­molecular layers lying parallel to (100)

N′-[(2Z)-4-Oxo-4-phenyl­but-2-en-2-yl]pyridine-4-carbohydrazide

There are significant twists in the title compound, C16H15N3O2, as seen in the dihedral angle between the benzene and adjacent but-2-enal group [29.26 (4)°] and between the pyridine ring and amide group [24.79 (6)°]. A twist is also evident around the hydrazine bond [the C—N—N—C torsion angle is −138.25 (13)°]. The conformation about the ethene bond is Z. An intra­molecular N—H⋯O hydrogen bond involving the benzoyl O atom and leading to an S(6) motif is formed. Significant delocalization of π-electron density is found in this part of the mol­ecule. In the crystal, helical supra­molecular chains aligned along the b axis and mediated by N—H⋯O hydrogen bonds are formed

(E)-N′-[(2-Hy­droxy­naphthalen-1-yl)methyl­idene]-4-methyl­benzene­sulfono­hydrazide

In the title compound, C18H16N2O3S, the dihedral angle between the planes of the benzene ring and the naphthyl ring system is 83.37 (10)°. An intra­molecular O—H⋯N hydrogen bond occurs. Inter­molecular N—H⋯O hydrogen bonds stabilize the crystal structure. There is a π–π inter­action between the naphthyl ring systems [centroid–centroid distance = 3.7556 (15) Å]. In addition, naphth­yl–tolyl and naphth­yl–naphthyl C—H⋯π inter­actions are observed

N′-[(E)-2-Hy­droxy-5-iodo­benzyl­idene]furan-2-carbohydrazide monohydrate

The organic mol­ecule of the title monohydrate, C12H9IN2O3·H2O, features a disordered furyl ring with the major component [site occupancy = 0.575 (18)] having the carbonyl O and furyl O atoms syn, and the other conformation having these atoms anti. The mol­ecule is slightly twisted with the dihedral angle between the benzene and furyl rings being 10.3 (6)° (major component). An intra­molecular O—H⋯N(imine) hydrogen bond is formed. In the crystal, the water mol­ecule accepts a hydrogen bond from an amine H atom, and forms two O—H⋯O(carbon­yl) hydrogen bonds, thereby linking three different carbohydrazide mol­ecules. The result is a supra­molecular layer parallel to (001). The closest contacts between layers are of the type I⋯I, at a distance of 3.6986 (6) Å

(E)-4-Hydroxy-N′-(2-hydroxy-5-iodobenzylidene)benzohydrazide methanol monosolvate

In the title compound, C14H11IN2O3·CH4O, the dihedral angle between the benzene rings is 33.2 (3)°. The molecule displays trans and anti conformations about the C=N and N—N bonds, respectively. There is an intramolecular O—H...N(azomethine) hydrogen bond. Intermolecular N—H...O and O—H...O hydrogen bonds consolidate molecules into a three-dimensional architecture

N,N′-(Pyridine-2,6-diyl)dibenzamide

The molecule of the title compound, C19H15N3O2, is completed by the application of crystallographic twofold symmetry, with the pyridine N atom lying on the rotation axis. The molecular structure is approximately planar, the dihedral angle between the mean planes of the pyridine and benzene rings being 7.53 (11)°. In the crystal, N—H...O hydrogen bonds link the molecules into a two-dimensional array perpendicular to the c axis