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)

Abstract

In the salt 1-methylpiperazine-1,4-diium bis(dihydrogen phosphate), C5H13N22+·2H2PO4−, (I), and the solvated salt 2-(pyridin-2-yl)pyridinium dihydrogen phosphate–orthophosphoric acid (1/1), C10H9N2+·H2PO4−·H3PO4, (II), the formation of O—H...O and N—H...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...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...O and C—H...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.