Multisubstituted Imidazolo[4,5-d]pyridazine Fused Ring System Resulting from Nitroamine-Nitroimine Tautomerism

Hydrogen-Free Explosive of N-Azo-Bridged 1,2,4-Triazole: A Novel Nitrogen-Chain-Extended Compound with Exceptional Energy Performance

The design of high-energy-density materials (HEDMs) and the investigation of energy limits have consistently represented a focal point and a significant challenge in research. This study prepared a hydrogen-free compound, BLG-102, with high nitrogen content (66.6%) using an energetic block design based on a long nitrogen chain (N6). BLG-102 has a high crystal density of 1.85 g·cm-3, with a measured crystal density of 1.82 g·cm-3. It also achieves zero oxygen balance (based on CO), excellent enthalpy of formation, and good conjugate planarity and aromaticity. BLG-102 demonstrates exceptional detonation performance with a high detonation velocity (VD = 9311 m·s-1) and detonation pressure (P = 38.5 GPa). These values are superior to the well-known energetic compound RDX (VD = 8991 m·s-1, P = 35.2 GPa), and are comparable to HMX (VD = 9144 m·s-1, P = 39.2 GPa). Nevertheless, BLG-102 exhibits slightly higher but acceptable sensitivity (IS = 5 J, FS = 54 N). BLG-102 demonstrates remarkable capabilities in laser initiation. Notably, a 10 mg charge of BLG-102 can effectively detonate 20 mg of RDX, producing a pore diameter of 11.44 mm in the lead plate (2 mm thick). The integrated design approach using the block design concept─combining nitro, azide, and long nitrogen chain structures with a 1,2,4-triazole framework─significantly enhances the energy performance of 1,2,4-triazole compounds. It breaks through the energy limit of already known 1,2,4-triazole-based compounds and provides a new idea for the design and synthesis of HEDMs with high performance.

Facile synthesis of thermally stable tetrazolo[1,5-b][1,2,4]triazine substituted energetic materials: synthesis and characterization

Various thermally stable energetic materials with high nitrogen content, low sensitivity and better detonation performance were synthesized. The versatile functionalization of 1,2,4-triazine involving the introduction of oxadiazole and tetrazole is discussed. All the compounds were fully characterized using IR, multinuclear NMR spectroscopy, elemental analysis, and high-resolution mass spectrometry. Compounds 2, 3, 9 and 12 were further verified using single-crystal X-ray analysis. Compound 9 can be considered a melt-cast explosive due to its lower onset melting temperature (112 °C). The detonation velocity, pressure, density, and heat of formation of all the synthesized compounds range between 7056 and 8212 m s^-1, 17.57 and 23.78 GPa, 1.70 and 1.81 g cm^-1, and 43 and 644 kJ mol^-1, respectively. Due to the high nitrogen percentage (53 to >72%), these molecules can be used in car airbag applications. Due to the high thermal stability (>220 °C) and lower sensitivity, these compounds can be potentially used as high-performing thermally stable secondary energetic materials.

Energetic Gem-dinitro Salts with Improved Thermal Stability by Incorporating with A Fused Building Block

Thermal stability is one of the most significant properties for the safety of energetic materials, finding a stable skeleton with suitable energetic groups is always a primary test. In this work, an unusual aminohydrazone cyclization strategy was used in the synthesis of a new series of gem-dinitro 1,2,4-triazolo[4,3-b][1,2,4,5]-tetrazine compounds with desirable thermal stability (≥197 °C). All of the new compounds were fully characterized by infrared (IR), NMR, differential scanning calorimetry, single crystal X-ray diffraction, and elemental analysis. The decomposition temperature of potassium salt 2 is 288 °C, reaching the level of HMX. All of these performances have demonstrated the effective synthesis strategy for innovatively combining geminal dinitro groups with fused rings.