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.

A fused-ring conjugated energetic molecule, 4-amino-3,7-dinitro-[1,2,4]triazolo[5,1-c] [1,2,4]triazine (TTX), has been synthesized in good yield in a two-step process starting from the known 5-amino-3-nitro-1H-1,2,4-triazole (ANTA). Characterization of TTX shows that it possesses energetic properties approaching those of 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX), but with a higher thermal stability and lower sensitivity towards impact and friction.

Ammonium perchlorate (AP) is most often used as a practical solid rocket propellant because of its excellent performance. However, AP has many shortcomings, including instability, high negative enthalpy of formation, and claimed health and environmental issues resulting from its combustion products. The pursuit of highly dense, high-performance, and environmentally friendly oxidizers as solid propellants has long attracted scientists around the world. In this work, bis­(3-nitro-1-(trinitromethyl)-1H-1,2,4-triazol-5-yl)­methanone (3) was obtained from bis­(3-nitro-1H-1,2,4-triazol-5-yl)­methane (1) with chloroacetone followed by nitration. The structure of 3 was confirmed by elemental analysis and single-crystal X-ray diffraction. By introducing the carbonyl moiety, the density of 3 was increased to 1.945 g/cm3 and the decomposition temperature increased to 164 °C. Compound 3 is a green energetic oxidizer that has a positive oxygen balance (+8.7%), a high specific impulse (218 s), and an acceptable sensitivity (9 J, 240 N), making it a practical replacement for AP in solid rocket propellant formulations.

This work demonstrates the fine-tuning of the properties of energetic compounds by bridging different azole based energetic rings.

An oxygen-rich energetic compound, 1,3-bis­(trinitromethyl)-1,2,4-triazole (13), was obtained by a two-step nitration and found to have an excellent crystal density of 1.90 g/cm3 confirmed by X-ray single-crystal diffraction. This highly dense material, as a green energetic oxidizer, features an attractive positive oxygen balance, an acceptable sensitivity, and a good enthalpy of formation, making it a competitive replacement for AP.