4-{[(E)-2,3-Dihy­droxy­benzyl­idene]amino}-N-(5-methyl-1,2-oxazol-3-yl)benzene­sulfonamide

In the title compound, C₁₇H₁₅N₃O₅S, the 2,3-dihy­droxy­benzaldehyde unit is oriented at a dihedral angles of 16.83 (10) and 78.87 (6)° with the anilinic and 5-methyl-1,2-oxazol-3-amine groups, respectively. An S(6) loop exists due to intramolecular O—H...N hydrogen bonding. In the crystal, inversion dimers with R₂²(8) rings are formed due to N—H...N hydrogen bonding between the 5-methyl-1,2-oxazol-3-amine groups. These dimers are inter­linked by O—H...O hydrogen bonds, forming chains along [101] and resulting in R₂²(26) rings. π–π inter­actions occur between the central benzene rings with a centroid–centroid distance of 3.7928 (16) Å.

2-[(E)-({4-[(4,6-Dimethyl­pyrimidin-2-yl)sulfamo­yl]phen­yl}iminio)meth­yl]-6-hy­droxy­phenolate

The title compound, C₁₉H₁₈N₄O₄S, exists as a zwitterion in the solid state, with nominal proton transfer from a phenol group to the imine N atom. The 2,3-dihy­droxy­benzaldehyde fragment is oriented at a dihedral angle of 35.51 (11)° to the adajacent aniline group and makes a dihedral angle of 76.99 (6)° with the 4,6-dimethyl­pyrimidin-2-amine group. Intra­molecular O—H...O and N—H...O hydrogen bonds close S(5) and S(6) rings, respectively; the same O atom accepts both bonds. In the crystal, polymeric chains along [001] are formed from mol­ecules joined end-to-end by N—H...O and O—H...N hydrogen bonds; these feature R₂³(6) loops. The polymeric chains are linked by C—H...O inter­actions and there are π–π inter­actions between the pyrimidine rings with a centroid–centroid distance of 3.446 (2) Å.

4-Bromo-2-{(E)-[(3,4-dimethyl­phen­yl)imino]­meth­yl}phenol

In the title compound, C₁₅H₁₄BrNO, the dihedral angle between the aromatic rings is 4.10 (11)° and the mol­ecule is close to planar (r.m.s. deviation for the non-H atoms = 0.053 Å). An intra­molecular O—H...N hydrogen bond closes an S(6) ring. In the crystal, very weak C—H...π inter­actions are observed.