Combining 5,6-fused triazolo-triazine with pyrazole: A novel energetic framework for heat-resistant explosive

• Three C–C polycyclic compounds containing fused-ring moiety with pyrazole ring are obtained by one-step or two-step ring-closure reaction. • These compounds possess good energy performances, safety and thermal stability. • Crystal structure analysis and theoretical calculation are carried out. • Compound 7 has the potential application as a heat-resistant explosive for replacement of HNS. In recent years, the exploration of thermodynamically stable explosives has attracted the great attention due to the rapid development of astronautics and deep-well perforation industries. Here, three C–C bonded polycyclic compounds combining fused-ring motifs with pyrazoles were obtained through one-step or two-step ring-closing reaction using nitroacetonitrile as a reagent. All compounds were characterized by multinucler NMR spectroscopy ( 1 H, 13 C), infrared spectroscopy (IR), elemental analysis, differential scanning calorimetry (DSC) as well as sensitivities test. Compounds 3 , 5 and 7 were further characterized by single crystal X-ray diffraction. Compounds 3 ( T d = 317 °C, IS > 40 J) and 5 ( T d = 249 °C, IS = 32 J) shows higher decomposition temperature and lower impact sensitivity than RDX ( T d = 204 °C, IS = 7.4 J). Compound 7 has higher detonation properties (8476 m s −1 , 29.86 GPa), higher decomposition temperature (332 °C) and lower impact sensitivity (IS > 40 J) than traditional heat-resistant explosive HNS (7612 m s −1 , 24.3 GPa, 318 °C, 5 J). These results imply that compound 7 has the potential to be a novel candidate for heat-resistant explosive.