3,7-Dinitroimidazo[1,2-b]pyridazine-6,8-diamine: A promising building block for advanced heat-resistant and low-sensitivity energetic materials

Constructing heat-resistant fused heterocyclic compounds is increasingly fascinating in the field of energetic materials due to their excellent energy, high thermal stability, and low sensitivity, as well as high density in general. This study synthesized a novel heat-resistant explosive based on the imidazo [1,2-b]pyridazine fused ring，3,7-dinitroimidazo [1,2-b]pyridazine-6,8-diamine (5)，using a three-step facile method. This compound exhibited a high density (1.856 g cm⁻³) and low mechanical sensitivities (IS = 40 J, FS = 350 N). Meanwhile, it displayed a higher thermal decomposition temperature of 324 °C compared to conventional heat-resistant explosive HNS (T_d = 318 °C). In addition, it demonstrated significantly higher detonation performance (D = 8336 m s⁻¹, p = 27.25 GPa) than both TNT (D = 6881 m s⁻¹, p = 19.5 GPa) and HNS (D = 7612 m s⁻¹, p = 24.3 GPa). Theoretical analysis shows that the intramolecular hydrogen bonding interactions of NH₂–NO₂–NH₂ might be the main reason for the heat resistance of energetic materials based on the imidazo [1,2-b]pyridazine fused ring. The results of this study suggest that compound 5 is a promising building block and a candidate for heat-resistant energetic materials.