A zwitterionic fused-ring framework as a new platform for heat-resistant energetic materials

Owing to their significant application potential in national defense and aerospace technology, the development of energetic materials with high heat resistance and high energy has attracted great attention recently. Herein, a zwitterionic strategy was explored for the preparation of a new heat-resistant energetic material. Through this strategy, a zwitterionic energetic material, 2,6-diamino-9-iminio-3,5-dinitro-9H-dipyrazolo[1,5-a:5′,1′-d][1,3,5]triazin-4-ide (ZDPT), was prepared employing a simple method. The molecular and crystal structures of ZDPT were comprehensively examined using nuclear magnetic resonance (NMR) spectroscopy and single-crystal X-ray diffraction. The unique zwitterionic structure of ZDPT is rarely observed in energetic materials. ZDPT exhibited exceptionally high thermal stability with an onset decomposition temperature of 347 °C and a peak temperature of 380 °C, which was higher than that of most traditional heat-resistant energetic materials and the highest among energetic zwitterions and energetic ion salts. Moreover, ZDPT exhibited excellent energy performance and surprisingly low sensitivity. The detonation velocity was 8390 m s⁻¹, which outperformed that of many heat-resistant energetic materials. The impact sensitivity and fraction sensitivity of ZDPT were higher than 40 J and 360 N, respectively. The extremely high thermal stability and low mechanical sensitivity were strongly related to the zwitterionic structure and the presence of a large π electron conjugation system of ZDPT making ZDPT a potential candidate for heat-resistant energetic materials.