2-(3-Aminopyridinium-1-yl)-3-carboxypropanoate monohydrate

The title compound, C9H10N2O4·H2O, was obtained as a zwitterion derived from the nucleophilic attack of 3-aminopyridine on the fumaric α,β-system. Within the molecule, the aminopyridine moiety and the carboxylate and carboxylic acid fragments form dihedral angles of 68.6 (2) and 62.8 (2)°, respectively. The geometry adopted by the molecule does not allow the formation of centrosymmetric dimeric hydrogen-bonded units; instead chains along the a axis are linked by COO—H...OOC motifs. These chains are interconnected by N—H...O and O—H...O hydrogen bonds involving the carboxylic acid and carboxylate units and the solvent water molecules.