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The incorporation of trinitrophenyl-modified 1,3,4-oxadiazole fragments is commonly observed in high-energy molecules with heat-resistant properties. This study explores the strategy of developing heat-resistant energetic materials by incorporating trinitrophenyl and an azo group into 1,3,4-oxadiazole, which involved the synthesis and characterization of (E)-1,2-bis(5-(2,4,6-trinitrophenyl)-1,3,4-oxadiazol-2-yl)diazene (2), N-(5-(2,4,6-trinitrophenyl)-1,3,4-oxadiazol-2-yl)nitramide (3), and the energetic salts of 3. Characterization techniques employed included 1H and 13C NMR, IR and elemental analysis. Additionally, the structures of 2 and 3 were validated using single crystal X-ray analysis. To further understand the physical and chemical characteristics of these novel energetic compounds, various calculations and measurements were performed. Compound 2 exhibits excellent thermostability (Td = 294 °C), which is comparable to that of traditional heat-resistant explosive HNS (Td = 318 °C). But 2 is insensitive towards impact (>40 J) and friction (>360 N), surpassing HNS (5 J, 240 N), suggesting that compound 2 deserves further investigation as a potential heat-resistant explosive. [ABSTRACT FROM AUTHOR]

Historically hydrazine (N2H4) has served an essential function as a fuel in liquid rocket propellants; however, its intrinsic volatility and toxicity pose significant challenges in fulfilling the requirements for environmentally friendly and high-performance propellants. Introducing hydrazine onto a nitrogen-rich framework offers the possibility to use it as solid-rocket propellant. Now for the first time both hydrazine and nitroamine groups, energetic small groups, were introduced onto a tetrazine ring through stepwise functionalization. N-(6-(3,5-Dimethyl-1H-pyrazol-1-yl)-1,2,4,5-tetrazin-3-yl)nitramide (3) serves as an energetic intermediate, which upon reaction with hydrazine or ammonia results in the synthesis of unsymmetrically substituted tetrazine derivatives (4 and 8) via nucleophilic substitution and salt formation (a domino or cascade reaction). Compounds 5 and 9 (salts of 4 and 8, respectively) exhibit detonation properties on a par with RDX, providing the added benefits of high nitrogen content and reduced sensitivity, and 7 and 11 (neutral derivatives of 4 and 8, respectively) show promising propulsive properties, highlighting their potential as solid rocket propellants. This research will significantly advance the synthesis of unsymmetrically substituted tetrazines, enabling precise control over their energetic properties. [ABSTRACT FROM AUTHOR]

Predicting crystal density of energetic materials accurately critically impacts assessment of their detonation potential, with higher density directly improving energetic performance. This new approach will help in density prediction to enable accelerated computational material discovery. By refining Politzer's approach using rigorously validated B3LYP quantum calculations and Multiwfn's precise structural elucidation, our optimized protocol substantially enhances predictive accuracy, marking a significant leap over traditional approaches. This streamlined and efficient framework spearheads high-fidelity virtual screening to transformatively expedite the development of novel, potent energetic candidates. Moreover, this research accentuates the decisive impact of refined computational techniques on elucidating structure–property relationships early-on, paving the way to accelerated development of promising energetic materials. Future work may concentrate on expanding training datasets to further improve model robustness and computational efficiency. Overall, this transformative density prediction workflow delivers a more precise approach to fundamentally advanced energetic material innovation. [ABSTRACT FROM AUTHOR]

Development of thermally stable, insensitive materials with attractive physiochemical properties continues to be heavily pursued in the field of energetic materials. High-energy-density compounds assembled by the combination of polynitro, nitroamino or azo groups and nitrogen-rich frameworks are often thermally unstable and sensitive to impact and friction. This conflicting nature of energy and stability strongly encourages designers of molecules to study existing structures at the molecular level in order to develop new methodologies for construction of potential energetic materials. In this work, a robust strategy which takes advantage of π-philic molecular recognition between planar energetic anions and cations is pursued. Our work not only generates insights for the design and synthesis of new energetic sandwich salts with good thermal stability and low sensitivity but also inspires the enrichment of a variety of new excellent performing high-energy materials. [ABSTRACT FROM AUTHOR]

This study highlights for the first time the impact of positional isomerism on chemical reactivity which involves a domino reaction, salt formation, cyclization, and nucleophilic substitution. The unprecedented reactivity occurs upon treating sensitive 5-azido-3,4-dinitropyrazole (1) with nitrogen rich bases. This results in the development of the first examples of fused catenated N5 pyrazolo[1,5-d]tetrazole-based energetic salts. The compound structures of 1, 2, and 3 were obtained by single-crystal analysis. Compounds 2 (Dv: 9202 m s−1; P: 32.08 GPa) and 3 (Dv: 8749 m s−1; P: 31.26 GPa) displayed excellent detonation properties (calculated) and good sensitivities (IS ≥ 20 J; FS ≥ 240 N), which are comparable to RDX. The thermal stability of compound 2 (185 °C) further suggests its significant potential use as a secondary explosive. Compound 1 exhibits high detonation properties (Dv: 9023 m s−1; P: 35.3 GPa) and sensitivity to external stimuli (IS: 8 J; FS: 80 N), indicating it has potential as a metal-free primary explosive. [ABSTRACT FROM AUTHOR]

Nitrogen‐rich energetic materials based on five‐membered azoles, such as tetrazoles, triazoles, oxadiazoles, pyrazoles, and imidazoles, have garnered significant attention in recent years due to their environmental compatibility while maintaining high performance. These materials, including explosives, propellants, and pyrotechnics, are designed to release energy rapidly and efficiently while minimizing the release of toxic or hazardous byproducts and have attracted potential applications in the defense and space industries. The presence of extensive NC, NN, and NN high energy bonds in azoles provides high enthalpies of formation and facilitates intermolecular interactions through π‐stacking which may help with reducing sensitivity to external stimuli. Now, we report on the synthesis and energetic properties of N‐(5‐(1H‐tetrazol‐5‐yl)‐1,3,4‐oxadiazol‐2‐yl)nitramide (5) and its energetic salts. These new high nitrogen–oxygen‐containing materials have attractive feature applications of insensitivity and increased performance. [ABSTRACT FROM AUTHOR]