Multipurpose [1,2,4]triazolo[4,3-b][1,2,4,5] tetrazine-based energetic materials

Two series of [1,2,4]triazolo[4,3-b][1,2,4,5]tetrazine-based energetic materials were synthesized effectively by using monosubstituted tetrazine or tetrazine-based fused rings as starting materials. Among them, compound 5 exhibits excellent insensitivity toward external stimuli (IS = 43 J and FS > 360 N) and a very good calculated detonation performance (D_v = 9408 m s⁻¹ and P = 37.8 GPa) that are comparable to the current secondary-explosive benchmark, CL-20, which strongly suggests 5 as a secondary explosive. The azo compound 10 has a remarkable measured density of 1.91 g cm⁻³ at 20 °C, excellent thermal stability (T_d = 305 °C), and very good calculated detonation performance (D_v = 9200 m s⁻¹ and P = 34.8 GPa), which outperforms all current heat-resistant explosives. Compound 10 has a significant potential as a heat-resistant explosive. Compounds 14, 17 and 19 are very sensitive (IS ≤ 2 J and FS ≤ 100 J) but exhibit excellent calculated detonation performance (D_v ≥ 8690 m s⁻¹ and P ≥ 30.2 GPa) which are very high values among current azide-containing primary explosives. These attractive features suggest strong possibilities for applications as primary explosives. A detailed study based on X-ray diffraction is used to illustrate the relationship between weak interactions and sensitivity of energetic materials. Attempts were made to design next-generation fused ring energetic materials for different applications as an alternating kind or site of the substituent group(s).