High stability N-rich energetic materials based on 5,5'-(1H-pyrazole-3,5-diyl)bis(4H-1,2,4-triazole-3,4-diamine)

Abstract. Improving the thermostabilities and the mechanical sensitivities to develop the heat resistant and insensitive N-rich energetic materials has become a new trend during recent years. Here, a novel N-rich energetic material, 5,5'-(1H-pyrazole-3,5-diyl)bis(4H-1,2,4-triazole-3,4-diamine) (N%: 64.10), was prepared through the introduction of an energetic pyrazol bridge to connect two diamino triazole groups, based on it, a series of energetic salts were synthesized and characterized. Additionally, the perchlorate salt, 4,5-diamino-3-(3-(4,5-diamino-4H-1,2,4-triazol-3-yl)-1H-pyrazol-5-yl)-4H-1,2,4-triazol-1-ium perchlorate, was investigated using the single crystal XRD to detailly figure out the internal molecular structures, also, the existence of huge hydrogen bonds shown in the crystal structure demonstrated it a heat resistant and insensitive energetic material. Interestingly, although 5,5'-(1H-pyrazole-3,5-diyl)bis(4H-1,2,4-triazole-3,4-diamine) exhibited a symmetrical structure, it cannot form a bivalent ionic salt, all derivatives manifested as monoionic salts. All the novel energetic materials in this study exhibited improved performances: superior heat of formation (908.8 ~ 1415.4 KJ mol^-1) to generate excellent detonation performances (Dv: 7850 to 8355 m s^-1, P: 21.46 to 25.55 GPa) with low mechanical sensitivities (IS > 40 J, FS > 360 N) and high decomposition temperatures (241 ~ 344 °C). Besides, non-covalent interactions were evaluated and discussed to explain the outstanding stabilities. The comprehensive performances of 5,5'-(1H-pyrazole-3,5-diyl)bis(4H-1,2,4-triazole-3,4-diamine) made it a promising high-stability energetic material.