Crystal structures and hydrogen bonding in the co-crystalline adducts of 3,5-di-nitro-benzoic acid with 4-amino-salicylic acid and 2-hy-droxy-3-(1H-indol-3-yl)propenoic acid.

The structures of the co-crystalline adducts of 3,5-di-nitro-benzoic acid (3,5-DNBA) with 4-amino-salicylic acid (PASA), the 1:1 partial hydrate, C7H4N2O6·C7H7NO3·0.2H2O, (I), and with 2-hy-droxy-3-(1H-indol-3-yl)propenoic acid (HIPA), the 1:1:1 d (6)-dimethyl sulfoxide solvate, C7H4N2O6·C11H9NO3·C2D6OS, (II), are reported. The crystal substructure of (I) comprises two centrosymmetric hydrogen-bonded R 2 (2)(8) homodimers, one with 3,5-DNBA, the other with PASA, and an R 2 (2)(8) 3,5-DNBA-PASA heterodimer. In the crystal, inter-unit amine N-H⋯O and water O-H⋯O hydrogen bonds generate a three-dimensional supra-molecular structure. In (II), the asymmetric unit consists of the three constituent mol-ecules, which form an essentially planar cyclic hydrogen-bonded heterotrimer unit [graph set R 3 (2)(17)] through carboxyl, hy-droxy and amino groups. These units associate across a crystallographic inversion centre through the HIPA carb-oxy-lic acid group in an R 2 (2)(8) hydrogen-bonding association, giving a zero-dimensional structure lying parallel to (100). In both structures, π-π inter-actions are present [minimum ring-centroid separations = 3.6471 (18) Å in (I) and 3.5819 (10) Å in (II)].