Two metal-free explosives, tetrazolo­[1,5-b]­pyridazine-containing molecules [6-azido-8-nitrotetrazolo­[1,5-b]­pyridazine-7-amine (3at) and 8-nitrotetrazolo­[1,5-b]­pyridazine-6,7-diamine (6)], were obtained via straightforward two-step synthetic routes from commercially available reagents. Compound 3at displays an excellent detonation performance (D v = 8746 m s–1 and P = 31.5 GPa) that is superior to commercial primary explosives such as lead azide and diazodinitrophenol (DDNP). Compound 6 has superior thermal stability, remarkable insensitivity, and good detonation performance, strongly suggesting it as an acceptable secondary explosive. The initiating ability of compound 3at has been tested by detonating 500 mg of RDX with a surprisingly low minimum primary charge of 40 mg. The extraordinary initiating power surpasses conventional primary explosives, such as commercial DDNP (70 mg) and reported 6-nitro-7-azido-pyrazol­[3,4-d]­[1,2,3]­triazine-2-oxide (ICM-103) (60 mg). The outstanding detonation power of 3at contributes to its future prospects as a promising green primary explosive. In addition, the environmentally benign methodology for the synthesis of 3at effectively shortens the time from laboratory-scale research to practical applications.

The key to successfully designing high-performance and insensitive energetic compounds for practical applications is through adjusting the molecular organization including both fuel and oxidizer. Now a superior hydrogen-free 5/6/5 fused ring energetic material, 1,2,9,10-tetranitrodipyrazolo[1,5-d:5',1'-f][1,2,3,4]tetrazine (6) obtained from 4,4',5,5'-tetranitro-2H,2'H-3,3'-bipyrazole (4) by N-amination and N-azo coupling reactions is described. The structures of 5 and 6 were confirmed by single crystal X-ray diffraction measurements. Compound 6 has a remarkable room temperature experimental density of 1.955 g cm and shows excellent detonation performance. In addition, it has a high decomposition temperature of 233 °C. These fascinating properties, which are comparable to those of CL-20, make it very attractive in high performance applications.

Environmentally acceptable alternatives to toxic lead-based primary explosives are becoming increasingly important for energetic materials. In this study, potassium 4,4'-bis(dinitromethyl)-3,3'-azofurazanate, comprising two dinitromethyl groups and an azofurazan moiety, was synthesized and isolated as a new energetic 3D metal-organic framework (MOF). Several attractive properties, including a density of 2.039 g cm(-3) , a decomposition temperature of 229 °C, a detonation velocity of 8138 m s(-1) , a detonation pressure of 30.1 GPa, an impact sensitivity of 2 J, and friction sensitivity of 20 N make 4 a good candidate as a green primary explosive.

Nitrogen-rich heterocyclic compounds offer promising potential backbones for constructing various high energy density compounds. Selective diazotization of 3,5-diamino-4-nitropyrazole (1) with tert-butyl nitrite followed by treatment with the sodium salt of nitroacetonitrile gives rise to a fused pyrazolotriazine ring (5) surrounded by amino and nitro groups. Compound 5, confirmed by single-crystal X-ray diffraction, has a remarkable thermal decomposition temperature of 355 °C, a high density of 1.90 g cm–3, and low impact and friction sensitivities. The detonation performance is also superior to TATB. These advantages make 5 a promising candidate as a heat-resistant explosive.