Advanced tetracyclic heat-resistant energetic materials based on bis(4-nitropyrazole) bridged 1,2,4-triazole†

In recent years, with the development of deep coal mines and petroleum resources and the expansion of the aerospace industry, the pursuit of heat-resistant energetic materials with high thermal stability and high energy has been increasing. Bis(4-nitropyrazole) was employed as an energy bridge to link 1,2,4-triazole, thereby constructing a sophisticated tetracyclic framework in this study. A tetracyclic heat-resistant explosive 5,5′-(4,4′-dinitro-2H,2′H-[3,3′-bipyrazole]-5,5′-diyl)bis(4H-1,2,4-triazole-3,4-diamine) (3) and its derivatives 6–8 with excellent comprehensive performance have been successfully prepared. Particularly noteworthy is that compound 3 has a detonation velocity of 8604 m s⁻¹, which exceeds that of the conventional heat-resistant explosive HNS with a velocity of 7164 m s⁻¹. Furthermore, compound 3 has higher thermal stability (T_d = 340 °C) than HNS (T_d = 318 °C). In addition, the tetracyclic compound 3 also exhibited extraordinarily low sensitivity (IS > 40 J; FS > 360 N). These unique characteristics make it a potential candidate for novel heat-resistant and insensitive energetic materials.