Promising Thermally Stable Energetic Materials with the Combination of Pyrazole-1,3,4-Oxadiazole and Pyrazole-1,2,4-Triazole Backbones: Facile Synthesis and Energetic Performance.

Thermally stable energetic materials have broad applications in the deep mining, oil and natural exploration, and aerospace industries. The quest for thermally stable (heat-resistant) energetic materials with high energy output and low sensitivity has fascinated many researchers worldwide. In this study, two different series of thermally stable energetic materials and salts based on pyrazole-oxadiazole and pyrazole-triazole ( 3-23 ) with different explosophoric groups have been synthesized in a simple and straightforward manner. All the newly synthesized compounds were fully characterized by IR, ESI-MS, multinuclear NMR spectroscopy, elemental analysis, and thermogravimetric analysis-differential scanning calorimetry measurements. The structures of 3 , 7 , and 22 were supported by single-crystal X-ray diffraction studies. The density, heat of formation, and energetic properties (detonation velocity and detonation pressure) of all the compounds range between 1.75 and 1.94 g cm -3 , 0.73 to 2.44 kJ g -1 , 7689 to 9139 m s -1 , and 23.3 to 31.5 GPa, respectively. All the compounds are insensitive to impact (>30 J) and friction (>360 N). In addition, compounds 4 , 6 , 10 , 14 , 17 , 21 , 22 , and 23 show high onset decomposition temperature ( T d between 238 and 397 °C) than the benchmark energetic materials RDX ( T d = 210 °C), HMX (279 °C), and thermally stable HNS (318 °C). It is noteworthy that the pyrazole-oxadiazole and pyrazole-triazole backbones greatly influence their physicochemical and energetic properties. Overall, this study offers a perspective on insensitive and thermally stable nitrogen-rich materials and explores the relationship between the structure and performance.