1‐Methyl­piperazine‐1,4‐diium 4‐nitro­phthalate(2–) 4‐nitro­phthalic acid monohydrate

The title adduct, C₅H₁₄N₂²⁺·C₈H₃NO₆^2?·C₈H₅NO₆·H₂O, crystallizes in the monoclinic space group P2₁. All O atoms of the 4‐nitro­phthalate anions and neutral 4‐nitro­phthalic acid mol­ecules are involved in hydrogen bonding with the piperazine dication and the water mol­ecule of crystallization.