4-Amino-N-(4,6-dimethyl-pyrimidin-2-yl)-benzene-sulfonamide-4-nitro-benzoic acid (1/1).

In the asymmetric unit of the title co-crystal, C(7)H(5)NO(4)·C(12)H(14)N(4)O(2)S, there are two independent but conformationally similar heterodimers, which are formed through inter-molecular N-H⋯O(carb-oxy) and carbox-yl-pyrimidine O-H⋯N hydrogen-bond pairs, giving a cyclic motif [graph set R(2) (2)(8)]. The dihedral angles between the rings in the sulfonamide molecules are 78.77 (8) and 82.33 (9)° while the dihedral angles between the ring and the CO(2)H group in the acids are 2.19 (9) and 7.02 (10)°. A two-dimensional structure parallel to the ab plane is generated from the heterodimer units through hydrogen-bonding associations between NH(2) and sulfone groups. Between neighbouring two-dimensional arrays there are two types of aromatic π-π stacking inter-actions involving either one of the pyrimidine rings and a 4-nitro-benzoic acid mol-ecule [minimum ring centroid separation = 3.5886 (9) Å] or two acid mol-ecules [minimum ring centroid separation = 3.7236 (10) Å].