2,3-Diaminopyridinium 4-nitrobenzoate

In the title salt, C5H8N3 +·C7H4NO4 −, the pyridine N atom of the 2,3-diaminopyridine molecule is protonated. The protonated N atom and one of the two 2-amino groups are hydrogen bonded to the 4-nitrobenzoate anion through a pair of N—H⋯O hydrogen bonds, forming an R 2 2(8) ring motif. The carboxylate mean plane of the 4-nitrobenzoate anion is twisted by 3.77 (5)° from the attached ring and the nitro group is similarly twisted by 2.28 (10)°. In the crystal, the molecules are linked by N—H⋯O and C—H⋯O interactions into sheets parallel to (100).