[1,2,4]Triazolo[4,3-b]pyridazine as a building block towards low-sensitivity high-energy materials

In this work, bicyclic fused [1,2,4]triazolo[4,3-b]pyridazine was used to construct new low-sensitivity high-energy materials. Two exemplary compounds, 6,7-diamino-3,8-dinitro- [1,2,4]triazolo[4,3-b]pyridazine (1) and 7-amino-6-azido-3,8-dinitro-[1,2,4]triazolo[4,3-b]pyridazine (2), were synthesized and characterized. The properties of the energetic materials, including their detonation velocities (D_v: 8994 m·s⁻¹ for 1, 8819 m·s⁻¹ for 2) and detonation pressures (P: 34.1 GPa for 1, 32.4 GPa for 2) were evaluated based on their densities (ρ: 1.93 g·cm⁻³ for 1, 1.84 g·cm⁻³ for 2) and heats of formation (ΔH_f: 348 kJ·mol⁻¹ for 1, 684 kJ·mol⁻¹ for 2). Their impact and friction sensitivities were measured to be 20 J and > 360 N for 1 and 18 J and 360 N for 2. The onset decomposition temperatures of 1 and 2 were 234 °C and 217 °C, respectively; therefore, both compounds were highly energetic materials with low sensitivities and good thermostability.