Acridinium 6-carboxypyridine-2-carboxylate monohydrate

The title compound, C13H10N+·C7H4NO4 ·H2O or (acrH)+(pydcH) ·H2O, is a monohydrate of acridinium cations and a mono-deprotonated pyridine-2,6-dicarboxylic acid. The structure contains a range of non-covalent interactions, such as O—H...O, O—H...N and N—H...O hydrogen bonds, as well as π–π stacking [range of centroid–centroid distances = 3.4783 (5)–3.8059 (5) ]. The N—H...O hydrogen bond between the donor acridinium cation and the carboxylate acceptor is particularly strong. The average separation between the π-stacked acridinium planes is 3.42 (3) .