5-Diethyl­amino-2-[(E)-(2,4-dimeth­oxy­phen­yl)imino­meth­yl]phenol

The title Schiff base, C₁₉H₂₄N₂O₃, exists in the crystal structure in the phenol–imine tautomeric form with an intra­molecular O—H...N hydrogen bond. The planes of the aromatic rings form a dihedral angle of 36.8 (8)°. The crystal packing is characterized by C—H...O hydrogen bonds and π–π stacking inter­actions [centroid–centroid distance = 3.478 (4)Å].

4-Meth­oxy-2-{(E)-[(thio­phen-2-yl)methyl­imino]­meth­yl}phenol

The title Schiff base, C₁₃H₁₃NO₂S, adopts the phenol–imine tautomeric form and reveals an intra­molecular O—H...N hydrogen bond involving the hy­droxy group and the imino N atom, forming an S(6) ring. The mol­ecule is highly twisted with respect to the central imine group, which is reflected in the dihedral angle of 67.83 (10)° formed by the thienyl and phenol rings. The crystal packing is characterized by weak C—H...O and C—H...π inter­actions.

Ethyl 2-[2-(4-hy­droxy-3-meth­oxy­benzyl­idene)hydrazin-1-yl­idene]-3,4-dimethyl-2,3-dihydro-1,3-thia­zole-5-carboxyl­ate

The title compound, C₁₆H₁₉N₃O₄S, is almost planar, with a dihedral angle of 2.88 (9)° between the mean planes of the benzene and thia­zole rings. The mol­ecule adopts an E conformation about the two C=N bonds, with a C—N—N—C torsion angle of −177.01 (11)°. An intra­molecular C—H...O hydrogen bond exists between a thia­zole methyl group and the formic acid ethyl ester carbonyl O atom. In the crystal, mol­ecules are linked by O—-H...O hydrogen bonds, forming chains propagating along [2-10]. The chains are linked via C—H...O hydrogen bonds with R₂²(12) ring motifs, forming sheets lying parallel to (12-2). The sheets are further linked through out-of-plane C—H...N hydrogen bonds with R₂²(12) ring motifs and C—H...π inter­actions, forming an inter­esting three-dimensional supra­molecular architecture.