UC Davis

The title compound, C(13)H(10)N(+)·C(7)H(4)NO(4) (-)·H(2)O or (acrH)(+)(pydcH)(-)·H(2)O, is a monohydrate of acridinium cations and a mono-deprotonated pyridine-2,6-dicarb-oxy-lic acid. The structure contains a range of non-covalent inter-actions, 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) Å]. The N-H⋯O hydrogen bond between the donor acridinium cation and the carboxyl-ate acceptor is particularly strong. The average separation between the π-stacked acridinium planes is 3.42 (3) Å.