Novel metal–organic frameworks assembled from the combination of polynitro-pyrazole and 5-nitroamine-1,2,4-oxadiazole: synthesis, structure and thermal properties

Abstract

Energetic metal organic frameworks (EMOFs) is a hot topic in the field of energetic materials research. This paper reports two kinds of EMOFs based on methylene-linked polynitropyrazole and nitroamine 1,2,4-oxadiazole. Their structures were fully characterized by crystallography and their detonation performance and stability performance were explored. The results showed that the crystals of compounds 4 and 5 exhibited a 3D stacking phenomenon due to the action of a large number of hydrogen bonds and coordination bonds inside the crystal. In terms of stability, both 4 and 5 showed good thermal stability (T_SADT (4) = 204.4 °C and T_SADT (5) = 216.2 °C), but due to the difference in the number of energetic groups (–NO₂), the sensitivity of 4 (IS = 6.0 J and FS = 100 N) to mechanical stimuli is significantly lower than that of compound 5 (IS = 1.2 J and FS = 40 N). In terms of energy performance, it is this great advantage in the number of energetic groups that makes compound 5's (D_v = 8.059 km s⁻¹ and P = 30.9 GPa) detonation performance superior to that of 4 (D_v = 7.704 km s⁻¹ and P = 26.9 GPa). This research broadens the horizon for the development of EMOFs based on polynitropyrazole derivatives.