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.

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.

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

Properties of energetic compounds obtained by linking energetic pyrazoles to tetrazoles by meanso fNmethylene-C bridges can be fine-tuned.R eactions of pyrazole derivatives with chloroacetonitrile followed by conversion of the cyano group to tetrazole using click reactions in the presence of zinc chloride result in asymmetric N-methylene-C bridged azole-based energetic compounds. All the compounds were thoroughly characterized by IR and NMR [ 1 H, 13 C{ 1 H}, 15 N]s pectroscopy,e lemental analysis, and differential scanning calorimetry (DSC), and for two compounds,f urther supported by single-crystal X-ray diffraction studies.H eats of formation and detonation performances were calculated using Gaussian 03 and EXPLO5 v6.01 programs, respectively.I nitial studies show that this new approach is promisingf or synthesizing less sensitivee nergetic compoundsw ith finetuned properties.Chemistry of high-energy density materials (HEDMs) emphasizes pushing the limits of the energy contento fc ompounds, while maintaining minimal safety and environmental concerns.[1] One of the most commonly used explosives, RDX (1,3,5-trinitro-1,3,5-triazacyclohexane), in addition to being sensitive to physical stimuli,i sapotentialc arcinogen and is toxic because of the presence of the nitramine moiety.[2] Synthesis of new energetic materials with performance similar or surpassing that of RDX, while tailoring them for high personal and environmental safety,i sarecurring and interesting problem for chemists and materials scientists. [3][4][5] Unlike traditional energetic materials, such as TNT (2,4,6-trinitrotoluene) and RDX, which derive most of their power from the oxidation of the carbon backbone, many modern energetic compounds are based on nitrogen-rich heterocycles.[1] The presence of energetic NÀNa nd CÀNb onds in these materials support high performance because of large positive heats of formation and high densities. However,h igh performance and low sensitivity are often mutually exclusive. This is easily demonstrated with five-membered azoles, movingf rom pyrazoleto pentazole, as energetic performance increases, the stability concomitantly decreases.[6] Therefore, properb lending of differenth eterocyclic rings appears to be ap romising approach to reach ab alance between the energetic and physical properties of energetic compounds. It is seen that different types of azole rings have different properties, for example nitropyrazoles have good oxygen balance, high thermal stability,a nd low sensitivity,w hereas tetrazole-based compounds have high positive heats of formationa nd high nitrogen content. [7,8] Recently,w eh ave demonstrated the impact of fine tuning of energetic properties through bridging trinitropyrazoles and aminotetrazoles via N,N'-ethylene links.[9] Ethylene-bridged compounds have been found to be lesss ensitive, butt hey are often less energetic. However,m ethylene-bridged compounds are less explored, in part because of the greater difficulty in synthesis, and the lack of asuitable approachtobond diffe...

A family of 3,3'-bipyrazole-based energetic compounds having C-NO /N-NO functionalities was synthesized by using various nitrating conditions. These nitro derivatives of bipyrazole are significantly more dense and energetic compared to the corresponding nitropyrazole analogues while maintaining the desired thermal stability and sensitivity. Depending on the number and nature of energetic nitro groups (C-NO /N-NO ), different classes of energetic materials, such as green primary explosives, high-performance secondary explosives and heat-resistant explosives, were obtained. All the compounds were thoroughly characterized by IR, NMR [ H, C{ H}, N], elemental analysis, and differential scanning calorimetry (DSC). Four were also structurally characterized with single-crystal X-ray diffraction studies. Heats of formation and detonation performance were calculated using Gaussian 03 and EXPLO5 v6.01 programs, respectively.

A rare high energy density oxidizer with excellent thermal stability along with good oxygen balance and energetic properties was synthesized and fully characterized.