Synthesis, Structure, and Characterisation of Two New Open-Framework Zinc Phosphites of Varying Dimensionality

Abstract

Using homopiperazine (hpip) as a structure directing agent, two new zinc phosphites [H2hpip][Zn2(HPO3)3] (1) and [H2hpip][Zn3(HPO3)4] (2), have been synthesised and structurally characterised by IR spectroscopy, elemental analysis, thermogravimetric analysis, and powder and single-crystal X-ray diffractions. Although both compounds are constructed from the same ZnO4 and HPO3 building units, the final frameworks are distinctly different due to their different connectivity. Compound 1 displays a 2D layered structure with 8-membered ring apertures, while compound 2 possesses a (3,4)-connected 3D architecture with multidirectional intersecting 8- and 12-ring channels. In addition, the simultaneous occurrence of four types of 8-ring channels intersecting the large 12-ring apertures in 2 is unique and observed here for the first time.