2,3-Diamino­pyridinium 4-nitro­benzoate

In the title salt, C(5)H(8)N(3) (+)·C(7)H(4)NO(4) (−), 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).