Bis{4-[(4-pyridyl)ethenyl]pyridinium} 4-sulfonatobenzoate trihydrate

In the crystal structure of the title organic proton-transfer complex, 2C(12)H(11)N(2)(+) (.) C7H4O5S2- . 3H(2)O, the cations form one-dimensional chains via intermolecular N - H (. . .) N hydrogen bonds and these chains, in turn, form a two-dimensional network through pi - pi stacking interactions. In addition, the anions and water molecules are connected into a two-dimensional hydrogen-bonded network through intermolecular O - H (. . .) O hydrogen bonds. The two motifs result in sheets of cations and anions stacked alternately.