Four three-dimensional metal–organic frameworks assembled from 1H-tetrazole: Synthesis, crystal structures and thermal properties

Abstract

Four tetrazole-based energetic metal–organic frameworks (EMOFs), {[Zn5(Tz)9](NO3)·6H2O}n (1) [Zn(Tz)2]n (2) {[Cd5(Tz)9](NO3)·6H2O}n (3) and {[Mn5(Tz)9](NO3)·6H2O}n (4) (Tz = tetrazole) have been prepared by hydro/solvo thermal conditions using 1H-tetrazole and corresponding metal salts. X-ray single crystal diffraction analyses indicated that EMOFs 1, 2, 3 and 4 possess 3D porous structure. The metal ions in 1, 3, and 4 form an acs topology net with the six nitrogen atoms from μ3-Tz and μ4-Tz ligands. The Zn2+ ions in 2 form a diamond-like structure with four μ2-Tz ligands which was reported previously. The thermal stabilities were investigated by differential scanning calorimeter (DSC) and thermogravimety (TG). The results showed that four EMOFs exhibit high thermal stability (decomposition temperature up to 324.1 °C (1), 351.4 °C (2), 279.41 °C (3) and 332.75 °C (4), respectively). The thermal stability parameters (Te.0, Tb) were calculated. In addition, the standard molar enthalpies of formation (ΔfHmΘ) were calculated on the basis of the constant-volume combustion heat (ΔU) measured by using oxygen-bomb calorimetry. Lastly, the detonation performance (D, P) and mechanical sensitivity (IS, FS) of the four EMOFs were investigated.