2,3-Diamino-pyridinium 4-nitro-benzoate

In the title salt, C(5)H(8)N(3) (+)·C(7)H(4)NO(4) (-), the pyridine N atom of the 2,3-diamino-pyridine mol-ecule is protonated. The protonated N atom and one of the two 2-amino groups are hydrogen bonded to the 4-nitro-benzoate anion through a pair of N-H⋯O hydrogen bonds, forming an R(2) (2)(8) ring motif. The carboxyl-ate mean plane of the 4-nitro-benzoate 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 mol-ecules are linked by N-H⋯O and C-H⋯O inter-actions into sheets parallel to (100).