(E)-2-Meth­oxy-6-[(2-trifluoro­methyl­phenylimino)meth­yl]phenol

The title compound, C₁₅H₁₂NO₂F₃, adopts the phenol–imine tautomeric form. The two aromatic rings are twisted with respect to each other, with a dihedral angle of 17.83 (19)°. O—H...N and O—H...F intra­molecular inter­actions are found in the mol­ecule, and the solid-state structure is stabilized by inter­molecular C—H...O and C—H...F hydrogen bonds, to form a two-dimensional network.

2-Hydr­oxy-6-[(2-methoxy­phen­yl)amino­methylene]cyclo­hexa-2,4-dienone

The mol­ecule of the title compound, C₁₄H₁₃NO₃, adopts the keto–amine tautomeric form. An intra­molecular N—H...O hydrogen bond dictates the essentially planar mol­ecular geometry; the two benzene rings make a dihedral angle of 7.93 (7)°. The crystal packing is stabilized by inter­molecular O—H...O and C—H...O hydrogen bonds.

(Z)-6-{[1,3-Dihydr­oxy-2-(hydroxy­meth­yl)propan-2-ylamino]methyl­ene}-4-[(E)-(4-ethyl­phen­yl)diazen­yl]cyclohexa-2,4-dienone

The title compound, C₁₉H₂₃N₃O₄, adopts the keto-amine tautomeric form, with the H atom located on N rather than on O. This H atom is involved in a strong intra­molecular hydrogen bond. The configuration around the azo N=N double bond is trans and the dihedral angle between the two aromatic rings is 8.94 (2)°. The mol­ecules, with intra­molecular N—H...O hydrogen bonding, are linked by intermolecular O—H...O hydrogen bonds, forming a three-dimensional network.

(E)-2-[1,3-Dihydr­oxy-2-(hydroxy­meth­yl)propan-2-ylamino­methyl­ene]-4-[(4-ethyl­phen­yl)diazen­yl]-6-methoxy­cyclo­hexa­none

The title compound, C₂₀H₂₅N₃O₅, adopts the keto–amine tautomeric form and displays the characteristic features of azobenzene derivatives. Intra­molecular N—H...O and O—H...O and inter­molecular O—H...O inter­actions influence the conformation of the mol­ecules and the crystal packing.

(E)-5-(4-Chloro­phenyl­diazen­yl)salicylaldehyde

The molecule of the title compound, C₁₃H₉ClN₂O₂, is approximately planar and displays a trans configuration with respect to the central N=N double bond. The dihedral angle between the two aromatic rings is 3.69 (14)°. The mol­ecules are linked by inter­molecular O—H...O hydrogen bonds, forming a two-dimensional network.

(E)-5-(4-Bromo­phenyl­diazen­yl)salicylaldehyde

The molecule of the title compound, C₁₃H₉BrN₂O₂, is approximately planar and displays a trans configuration with respect to the N=N double bond. The dihedral angle between the two aromatic rings is 3.65 (16)°. The mol­ecules are linked by inter­molecular O—H...O hydrogen bonds, forming a two-dimensional network.

(E)-5-(4-Ethyl­phenyl­diazen­yl)salicylaldehyde

The molecule of the title compound, C₁₅H₁₄N₂O₂, is approximately planar and displays a trans configuration with respect to the N=N double bond. The dihedral angle between the two aromatic rings is 10.90 (14)°. The mol­ecules are stacked via weak C—H...π inter­actions.

(E)-5-[(3-Bromo­phen­yl)diazen­yl]-2-hydr­oxy-3-methoxy­benzaldehyde

The title structure, C₁₄H₁₁BrN₂O₃, displays the characteristic features of azobenzene derivatives. The two aromatic rings are nearly coplanar, forming a dihedral angle of 8.71 (12)°. There is a strong intra­molecular O—H...O bond, and weak π–π and C—H...π inter­actions stabilize the structure.

(E)-5-[(2-Fluoro­phen­yl)diazen­yl]-2-hydr­oxy-3-methoxy­benzaldehyde

The title compound, C₁₄H₁₁FN₂O₃, displays the characteristic features of azobenzene derivatives. Intra­molecular O—H...O and weak π–π inter­actions influence the conformation of the mol­ecules and the crystal packing. The azobenzene moiety of the mol­ecule has a trans configuration and the dihedral angle between the planes of the two aromatic rings is 10.13 (8)°.