title: 1,4-Bis(carb-oxy-meth-yl)piperazine-1,4-diium bis-(dihydrogen phosphate) dihydrate.
abstract: In the title salt, C(8)H(16)N(2)O(4) (2+)·2H(2)PO(4) (-)·2H(2)O, the piperazine ring is located around an inversion center and adopts a chair conformation. The dihydrogen phosphate anions and free water mol-ecules are linked via O-H⋯O hydrogen bonds into two-dimensional hydrogen-bonding layers, which are further connected through O-H⋯O and N-H⋯O hydrogen bonds involving the protonated piperazine into a three-dimensional supra-molecular network.
authors.affiliation: Department of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, People's Republic of China.
authors.forename: Lin
authors.initials: L
authors.lastname: Cheng
authors.forename: Li-Min
authors.initials: LM
authors.lastname: Zhang
authors.forename: Jian-Quan
authors.initials: JQ
authors.lastname: Wang