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.

3-Amino­pyridin-1-ium 3-carb­oxy­benzo­ate

In the title organic salt, C₅H₇N₂⁺·C₈H₅O₄⁻, the carb­oxy­lic group is nearly coplanar with the benzene ring [dihedral angle 1.9 (4)°] whereas the carboxyl­ate group is twisted relative to the benzene ring by 13.6 (4)°. In the crystal, N-H...O and O—H...O hydrogen bonds connect the components into a three-dimensional framework consisting of stacks of alternating pairs of anions and cations exhibiting π–π stacking inter­actions with centroid–centroid distances in the range 3.676 (2)–3.711 (1) Å. The π–π stacks extend along [110] and [-110].