2,9-Dimethyl-1,10-phenanthrolin-1-ium 2,4,5-tri­carb­oxy­benzoate monohydrate

In the preparation of the title hydrated salt, C₁₄H₁₃N₂⁺·C₁₀H₅O₈⁻·H₂O, a proton has been transfered to the 2,9-dimethyl-1,10-phenanthrolinium cation, forming a 2,4,5-tri­carb­oxy­benzoate anion. In the anion, the mean planes of the protonated carboxyl­ate groups form dihedral angles of 11.0 (5), 4.4 (5) and 80.3 (4)° with the benzene ring to which they are attached. The mean plane of the deprotonated carboxyl­ate group forms a dihedral angle of 10.6 (5)° with the benzene ring. In the crystal, the anions are involved in carb­oxy­lic acid O—H...O_carbox­yl hydrogen bonds, generating a two-dimensional network parallel to (001) containing R₄⁴(28) and R₄⁴(32) motifs. The 2,9-dimethyl-1,10-phenanthrolinium cations and water mol­ecules reside between the anion layers and are connected to the anions via N—H...O_water and O_water—H...O_carbox­yl hydrogen bonds. An intra­molecular O—H...O hydrogen bond is also observed in the anion.