Iodine-Mediated Furoxan Formation Facilitates the Synthesis of High-Density Tricyclic Fused Energetic Materials

Abstract

Fused cyclic energetic material, a special category of π-conjugate structures containing two or more rings, has been acknowledged as a potential energy source of high energy density in recent years. In the present work, a new tricyclic, fused energetic skeleton [1,2,5]oxadiazolo[3,4-d][1,2,4]triazolo[4,3-b]pyridazine-3-oxide was designed and synthesized. Two typical compounds, 4-azido-[1,2,5]oxadiazolo[3,4-d][1,2,4]triazolo[4,3-b]pyridazine-3-oxide and 4-amino-[1,2,5]oxadiazolo[3,4-d][1,2,4]triazolo[4,3-b]pyridazine-3-oxide, were synthesized and characterized by single-crystal X-ray diffraction, elemental analysis, NMR, and IR spectroscopy. Both energetic compounds exhibit densities of 1.773 and 1.939 g·cm–3 for 2 and 3, respectively. The energetic properties were calculated based on the density and the heat of formation. They possess a good detonation performance (Dv: 8664 m·s–1 for 2, 8817 m·s–1 for 3; P: 30.9 GPa for 2, 32 GPa for 3). Their impact and friction sensitivities were tested to be 7 J and 108 N for 2 and >40 J and 128 N for 3. The two energetic compounds also show satisfactory onset decomposition temperatures (2:183.7 °C; 3:195.3 °C) owing to fused furoxan frameworks. All these properties indicate that the above-mentioned new molecules may show their prospective application as versatile energetic materials and devices.