1-Piperonylpiperazinium 4-nitro­benzoate monohydrate

In the title hydrated salt [systematic name: 1-(1,3-benzodioxol-5-ylmeth­yl)piperazin-1-ium 4-nitro­benzoate monohydrate], C(12)H(17)N(2)O(2) (+)·C(7)H(4)NO(4) (−)·H(2)O, the piperazinium ring of the cation adopts a slightly distorted chair conformation. The piperonyl and piperazine rings are rotated with respect to each other with an N—C—C—C torsion angle of 45.6 (2)°. In the anion, the nitro group is almost coplanar with the adjacent benzene ring, forming a dihedral angle of only 3.9 (4)°. In the crystal, the cations, anions and water mol­ecules are linked through N—H⋯O and O—H⋯O hydrogen bonds into chains along the a axis. In addition, weaker inter­molecular C—H⋯O inter­actions are also observed within the chains. The anions form centrosymmetric couples through π-stacking inter­actions, with an inter­centroid distance of 3.681 (4) Å between the benzene rings.