From Nitro- to Heterocycle-Functionalized 1,2,4-Triazol-3-one Derivatives: Achieving High-Performance Insensitive Energetic Compounds

N-Methylene-C-linked nitropyrazoles and 1,2,4-triazol-3-one: thermally stable energetic materials with reduced sensitivity

Recently, there has been a surge in research focusing on triazolone-based energetic materials, propelled by their remarkable properties such as good detonation performance as well as acceptable thermal and physical stability. In this work, a novel combination of the triazolone framework with dinitropyrazoles has been attained using the N-methylene-C-linked approach. Different substituents (NH2, NO2, N3, OH) were utilized on the dinitropyrazole moiety to obtain neutral energetic compounds 3-5 and 8. Furthermore, the hydroxy derivative (compound 8) facilitates the formation of energetic salts 9-13 to fine-tune the overall properties further. All the novel compounds 3-13 were thoroughly characterized by IR, multinuclear NMR spectroscopy, high-resolution mass spectrometry (HRMS), and elemental analysis. Compounds 3, 4, 8, and 10 were further confirmed via15N NMR spectroscopy. The structure of compounds 3 and 8 was also confirmed through single-crystal X-ray diffraction studies. The majority of synthesized compounds showed good thermal stability as well as insensitivity toward external stimuli. Computational studies, including analyses such as Hirshfeld surface, non-covalent interaction, electrostatic potential surface, and HOMO-LUMO analysis, were conducted to examine the influence of substitution at the 4th position on the overall stability of compounds 3, 4, and 8.

Polynitro-1,2,4-triazole Energetic Materials with N-Amino Functionalization

Trinitromethyl and N-amino groups were innovatively incorporated into the framework of 1,2,4-triazole, resulting in 1-amino-5-nitro-3-(trinitromethyl)-1,2,4-triazole (2). Ammonium and hydrazinium salts of 1-amino-5-nitro-3-(dinitromethyl)-1,2,4-triazole were synthesized by acidification, extraction, and neutralization with bases from the potassium salt. All of the newly prepared energetic compounds were comprehensively characterized by using infrared spectroscopy, elemental analysis, nuclear magnetic resonance spectroscopy, and single crystal X-ray diffraction. Compound 2 exhibits favorable properties such as positive oxygen balance (OBCO2 = 5.8%), high density (1.88 g cm-1), good detonation performances (vD = 8937 m s-1, P = 35.5 GPa), and appropriate friction sensitivity (FS = 144 N). The potassium salt 3 demonstrates good thermal decomposition temperature (181 °C) and high density (1.98 g cm-1), while the ammonium salt and hydrazinium salt also display good thermal decomposition temperatures of 183 and 176 °C, respectively. Among these compounds, the ammonium salt exhibits the lowest mechanical sensitivities (FS = 144 N, IS = 6 J).

Structure and performance regulation of energetic complexes through multifunctional molecular self-assembly

The design of novel energetic compounds constitutes a pivotal research direction within the field of energetic materials. However, exploring the intricate relationship between their molecular structure and properties, in order to uncover their potential applications, remains a challenging endeavor. Therefore, employing multi-molecule assembly techniques to modulate the structure and performance of energetic materials holds immense significance. This approach enables the creation of a new generation of energetic materials, fueling research and development efforts in this field. In this study, a series of coordination compounds are synthesized by utilizing tetranitroethide (TNE) as an anion, which possesses a high nitrogen and oxygen content. The synthesis involves the synergistic modification between metal ions and small molecule ligands. Characterization of the obtained compounds is carried out using various techniques, including single crystal X-ray diffraction, IR spectroscopy, elemental analysis, and simultaneous TG-DSC analysis. Additionally, the energy of formation for these compounds is calculated using bomb calorimetry, based on the heat of combustion. The detonation performances of the compounds are determined through calculations using the EXPLO 5 software, and their sensitivities to external stimuli are evaluated.

Synthesis, crystal structure and Hirshfeld surface analysis of (3Z)-4-[(4-amino-1,2,5-oxa-diazol-3-yl)amino]-3-bromo-1,1,1-tri-fluoro-but-3-en-2-one

In the title compound, C6H4BrF3N4O2, the oxa-diazole ring is essentially planar with a maximum deviation of 0.003 (2) Å. In the crystal, mol-ecular pairs are connected by N-H⋯N hydrogen bonds, forming dimers with an R 2 2(8) motif. The dimers are linked into layers parallel to the (10) plane by N-H⋯O hydrogen bonds. In addition, C-O⋯π and C-Br⋯π inter-actions connect the mol-ecules, forming a three-dimensional network. The F atoms of the tri-fluoro-methyl group are disordered over two sites in a 0.515 (6): 0.485 (6) ratio. The inter-molecular inter-actions in the crystal structure were investigated and qu-anti-fied using Hirshfeld surface analysis.

Interaction of Nitrogen-Rich Cations with Azotriazolone Anions through Ion Exchange Results in the Formation of Energetically Stable and Insensitive Compounds

In our pursuit of promoting the green development of energetic materials and harnessing their functional benefits, we strive to address the inherent contradiction between energy and low sensitivity. In this regard, we have successfully constructed an azotriazole framework via environmentally friendly electrochemistry with a satisfactory yield of 62.3%. Through a simple ion-exchange process, we then synthesized nitrogen-rich salt derivatives of azotriazolone. These nitrogen-rich salts exhibit a wide range of nitrogen contents, ranging from 32.16 to 68.80%. Remarkably, crystallographic analysis of these green energy-containing salts reveals substantial advantages in terms of thermodynamic stability and low sensitivity. Experimental investigations have demonstrated a positive relationship between the nitrogen content and the pyrothermal performance of the azotriazolone derivatives. Of particular significance is compound 5, a triaminoguanidine salt, which exhibits an exceptionally high nitrogen content of 68.80%. It displays a detonation pressure of 28.2 GPa and a detonation velocity of 7939.4 m s-1. Moreover, the derivatives of azotriazolone salts demonstrate the formation of nitrogen-rich compounds, characterized by insensitive properties, attributed to the hydrogen-bonded network structures resulting from anion-cation interactions. With the exception of compound 5, which exhibits a friction sensitivity of 252 N, the remaining derivatives show a similar value of approximately 360 N. This suggests that azotriazolone serves as a promising material possessing both stabilizing properties and better detonation performance, thereby providing a favorable platform for the synthesis of novel compounds with advantageous properties.

Crystal structure of the double salt bis(5-amino-1,2,4-triazol-4-ium-3-yl)methane hydrogen oxalate hemioxalate, C8H11N8O6

C8H11N8O6, monoclinic, P21/n (no. 14), a = 5.6348(8) Å, b = 19.485(3) Å, c = 11.5316(17) Å, β = 101.013(2)°, V = 1242.8(3) Å3, Z = 4, R gt(F) = 0.0396, wR ref(F 2) = 0.1039, T = 296(2) K.

Crystal structure of bis(5-amino-1,2,4-triazol-4-ium-3-yl)methane sulfate, C5H10N8O4S

C5H10N8O4S, Orthorhombic, Pba2 (no. 32), a = 7.7320(11) Å, b = 12.8686(19) Å, c = 5.0657(8) Å, β = 90°, V = 504.04(13) Å3, Z = 2, R gt (F) = 0.0298, wR ref (F 2) = 0.0748, T = 296(2) K.