Bis[8-ethyl-5-oxo-2-(piperazin-4-ium-1-yl)-5,8-dihydropyrido[2,3-d]pyrimidine-6-carboxylic acid] 2,5-dicarboxybenzene-1,4-dicarboxylate octahydrate

The asymmetric unit of the title compound, 2C14H18N5O3+·C10H5O82 ·8H2O, contains one [H2ppa]+cation, one half of an [H2btec]2 anion (H4btec = 1,2,4,5-benzenetetracarboxylic acid and Hppa = 8-ethyl-5-oxo-2-piperazin-1-yl-5,8-dihydropyrido[2,3-d]pyrimidine-6-carboxylic acid) that is completed by inversion symmetry and four water molecules. In the crystal, the molecules are connected by intermolecular hydrogen-bonding interactions and π–π stacking between the benzene rings of the [H2btec]2 anion and the pyrimidine rings of the [H2ppa]+ cation [centroid–centroid distance = 3.597 (3) ], generating a three-dimensional supramolecular structure.