title: 4-({(Z)-5-[(Z)-3-Eth-oxy-4-hy-droxy-benzyl-idene]-3-methyl-4-oxo-1,3-thia-zolidin-2-yl-idene}amino)-benzoic acid dimethyl-formamide monosolvate.
abstract: The mol-ecular structure of the title compound, C20H18N2O5S·C3H7NO, represents an essentially planar 5-benzyl-idene-thia-zolidine moiety (r.m.s. deviation from planarity without ring substituents = 0.095 Å) to which the 4-amino-benzoic acid fragment is inclined at 76.23 (1)°. In the crystal, the benzoic acid mol-ecules are arranged in layers parallel to [001] which are built up from inversion dimers held together by head-to-tail phenol-carb-oxy O-H⋯O hydrogen bonds and head-to-tail π-π stacking inter-actions between the 5-benzyl-idene-thia-zolidine moieties (ring centroid distance = 3.579 Å). These layers are separated by the dimethyl-formamide solvent mol-ecules which are firmly anchored via a short O-H⋯O hydrogen bond [O⋯O = 2.5529 (10) Å] donated by the -COOH group.
authors.affiliation: Department of Chemistry, University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria.
authors.forename: Paul
authors.initials: P
authors.lastname: Kosma
authors.forename: Edgar
authors.initials: E
authors.lastname: Selzer
authors.forename: Kurt
authors.initials: K
authors.lastname: Mereiter