Crystal structure of 4-(dimethylamino)-pyridinium 4-aminobenzoate dihydrate

In the title hydrated molecular salt, C7H11N2+center dot C7H6NO2-center dot 2H(2)O, the cation is protonated at the pyridine N atom and the dihedral angle between the benzene ring and the CO2- group in the anion is 8.5 (2)degrees. In the crystal, the cation forms an N-H center dot center dot center dot O hydrogen bond to the anion and the anion forms two N-H center dot center dot center dot O hydrogen bonds to adjacent water molecules. Both water molecules form two O-H center dot center dot center dot O hydrogen bonds to carboxylate O atoms. In combination, these hydrogen bonds generate a three-dimensional network and two weak C-H center dot center dot center dot pi interactions are also observed.