Syntheses and structures of two open-framework zinc phosphites with extra-large 24-ring channels

Abstract: Two new three-dimensional open-framework zinc phosphites, [HCHA]2[Zn3(HPO3)4] (1) and [HCHPA]2[Zn3(HPO3)4] (2), have been synthesized under hydrothermal conditions, where CHA = cyclohexylamine and CHPA = cycloheptylamine. Both compounds are isostructural and exhibit a similar three-dimensional 3, 4-connected framework constructed by strictly alternating ZnO4 tetrahedra and pseudopyramids. The occurrence of extra-large tubular channels constructed by the concatenation of 24- and 30-ring windows along the [001] direction in the two structures is very unusual in known extra-large micropore materials. Crystal data: 1, rhombohedral, R-3, a = 32.9618(5) Å, c = 13.2818(3) Å, V = 12497.1(4) Å3, Z = 18, R 1 = 0.0445, wR 2 = 0.1068; 2, rhombohedral, R-3, a = 33.2184(4) Å, c = 13.1697(6) Å, V = 12585.3(6) Å3, Z = 18, R 1 = 0.0401, wR 2 = 0.0974. [Copyright &y& Elsevier]