4-({(Z)-5-[(Z)-3-Eth­oxy-4-hy­droxy­benzyl­idene]-3-methyl-4-oxo-1,3-thia­zolidin-2-yl­idene}amino)­benzoic acid dimethyl­formamide monosolvate

The mol­ecular structure of the title compound, C(20)H(18)N(2)O(5)S·C(3)H(7)NO, represents an essentially planar 5-benzyl­idene-thia­zolidine moiety (r.m.s. deviation from planarity without ring substituents = 0.095 Å) to which the 4-amino­benzoic acid fragment is inclined at 76.23 (1)°. In the crystal, the benzoic acid mol­ecules are arranged in layers parallel to [001] which are built up from inversion dimers held together by head-to-tail phenol–carb­oxy O—H⋯O hydrogen bonds and head-to-tail π–π stacking inter­actions between the 5-benzyl­idene-thia­zolidine moieties (ring centroid distance = 3.579 Å). These layers are separated by the dimethyl­formamide solvent mol­ecules which are firmly anchored via a short O—H⋯O hydrogen bond [O⋯O = 2.5529 (10) Å] donated by the –COOH group.