A dihydrogen phosphate anionic network as a host lattice for cations in 1-methylpiperazine-1,4-diium bis(dihydrogen phosphate) and 2-(pyridin-2-yl)pyridinium dihydrogen phosphate-orthophosphoric acid (1/1)

In the salt 1-methylpiperazine-1,4-diium bis(dihydrogen phosphate), C5H13N22+center dot-2H(2)PO(4)(-), (I), and the solvated salt 2-(pyridin-2-yl) pyridinium dihydrogen phosphate-orthophosphoric acid (1/1), C10H9N2+center dot H2PO4-center dot H3PO4, (II), the formation of O-H center dot center dot center dot O and N-H center dot center dot center dot O hydrogen bonds between the dihydrogen phosphate (H2PO4-) anions and the cations constructs a three-and two-dimensional anionic-cationic network, respectively. In (I), the self-assembly of H2PO4- anions forms a two-dimensional pseudo-honeycomb-like supramolecular architecture along the (010) plane. 1-Methylpiperazine-1,4-diium cations are trapped between the (010) anionic layers through three N-H center dot center dot center dot O hydrogen bonds. In solvated salt (II), the self-assembly of H2PO4- anions forms a two-dimensional supramolecular architecture with open channels projecting along the [001] direction. The 2-(pyridin-2-yl) pyridinium cations are trapped between the open channels by N-H center dot center dot center dot O and C-H center dot center dot center dot O hydrogen bonds. From a study of previously reported structures, dihydrogen phosphate anions show a supramolecular flexibility depending on the nature of the cations. The dihydrogen phosphate anion may be suitable for the design of the host lattice for host-guest supramolecular systems.