Energetic properties of bistetrazole derivatives are improved by the step-by-step introduction of functionalities which improve heat of formation, density, and oxygen content. The incorporation of unsaturation between bis(1 H -tetrazol-5-yl) and bis(1 H -tetrazol-1-ol) derivatives leads to planarity which enhances the density of the final product. In this manuscript, we have synthesized compounds 1,2-di(1 H -tetrazol-5-yl)ethane (4), ( E )-1,2-di(1 H -tetrazol-5-yl)ethene (5), and ( E )-5,5′-(ethene-1,2-diyl)bis(1 H -tetrazol-1-ol), (6) using readily available starting materials. Their corresponding dihydroxylammonium salts 7, 8 and 9 are obtained by reacting two equivalents of hydroxylamine (50% in water). New compounds are analyzed using IR, EA, DSC and multinuclear NMR spectroscopy ( 1 H, 13 C and 15 N). The solid-state structures of compounds 6, 7, 8 and 9 are confirmed by single-crystal X-ray diffraction. The energetic performances are calculated using the EXPLO5 (v6.06.02) code and the sensitivities towards external stimuli such as friction and impact are determined according to BAM standard. Compound 6 {( E )-5,5′-(ethene-1,2-diyl)bis(1 H -tetrazol-1-ol)} exhibits a surprisingly high density of 1.91 g cm −3 at 100 K (1.86 g cm −3 at 298 K). Its detonation velocity (9017 m s −1 ) is considerably superior to those of RDX (8795 m s −1 ), which suggests it is a competitive high-energy-density material.
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Nitro-based and nitro-free tri-cationic azole salts: a unique class of energetic green tri-ionic salts obtained from the reaction with nitrogen-rich bases
Nitrogen-rich heterocycles are essential for designing novel energetic green materials with the combination of high explosive performance and acceptable mechanical sensitivities. In this work, two sets of high nitrogen-azoles, derived from tetrazoles and triazole assemblies with N -trinitromethane, 5,5′-(2-(trinitromethyl)-2 H -1,2,3-triazole-4,5-diyl)bis(1 H -tetrazole) (TBTN) and N -methylene tetrazole, 5,5′-(2-((1 H -tetrazol-5-yl)methyl)-2 H -1,2,3-triazole-4,5-diyl)bis(1 H -tetrazole) (TBTT) are described. Their molecular structures were confirmed using multinuclear ( 1 H, 13 C, and 15 N) NMR spectra and single-crystal X-ray diffraction analysis. These molecules are attention attracting results emanating from methodologies utilized to access a unique class of tri-ionic salts in reaction with nitrogen-rich bases. The thermostabilities, mechanical sensitivities, and detonation properties of all new compounds were determined. Surprisingly, the nitro-based tri-cationic salts, 5b (Dv = 9376 m s −1 ) and 5c (Dv = 9418 m s −1 ), have excellent detonation velocities relative to HMX (Dv = 9144 m s −1 ), while those of the nitro-free tri-cationic salts, 8b·H2O (Dv = 8998 m s −1 ) and 8c·0.5H2O (Dv = 9058 m s −1 ), are superior to that of RDX (Dv = 8795 m s −1 ) and approach HMX values. Additionally, nearly all new compounds are insensitive to mechanical stimuli because of the high percentage of hydrogen bond interactions (HBs) between the anions and cations, which are evaluated using two-dimensional (2D) fingerprint and Hirshfeld surface analyses. It is believed that the work presented here is the first example of high-performing and insensitive tri-cationic energetic salts, which may establish a discovery platform for the “green” synthesis of future energetic materials.
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- Award ID(s):
- 1919565
- NSF-PAR ID:
- 10346969
- Date Published:
- Journal Name:
- Materials Advances
- Volume:
- 3
- Issue:
- 12
- ISSN:
- 2633-5409
- Page Range / eLocation ID:
- 5012 to 5018
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract The energetic compound 5,7‐diamino‐2‐nitro‐1,2,4‐triazolo[1,5‐a]‐1,3,5‐triazine (ANTT) was synthesized through the selective nitration of 2,5,7‐triamine‐1,2,4‐triazolo[1,5‐a]‐1,3,5‐triazine (TTT). This facile synthetic strategy yields a highly insensitive energetic nitrogen bicycle with potential for further functionalization. ANTT was chemically characterized by NMR, IR, and single crystal X‐Ray crystallography. Its energetic sensitivities (impact, friction) were experimentally determined, and its energetic performances were calculated for the first time.
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null (Ed.)Heat of formation and density have a significant influence on the detonation performance of a compound and are greatly influenced by the nitrogen and oxygen content of a material. Here a family of new materials with high oxygen and nitrogen content was synthesized and characterized. Compound 1 has a nitrogen and oxygen content of 85.3%, with a high density (1.93 g cm −3 ) and high detonation properties (detonation velocity v D = 9503 m s −1 ; detonation pressure P = 41 GPa). The ammonium salt 3 has a nitrogen and oxygen content of 84.9%, a density of 1.86 g cm −3 , a detonation velocity of 9317 m s −1 , and acceptable sensitivities (8 J, 120 N) which are similar to those of HMX . The potassium salt ( 5 ) was characterized by single-crystal X-ray diffraction.more » « less
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The assembly of nitrogen-rich building blocks determines the energy storage capacity and affects the stability of energetic materials. Owing to the environmentally harmful properties of the propellant, ammonium perchlorate (AP), much research has explored halogen-free replacements which often suffer from poor thermal stability. In our goal of balancing performance and stability, we report access to an energetic molecule (3) by smart assembly of an azo bridge into trinitromethyl triazoles. Compound 3 exhibits a decomposition temperature of 175 °C, which approaches the highest among reported trinitromethyl derivatives. The density (1.91 g cm −3 ) and oxygen balance (+29%) for 3 exceed other candidates, suggesting it as a high energy dense oxidizer (HEDO) replacement for AP in rocket propellants. One-step azo-involved cyclization of 3 give two fused nitro triazolones, (FNTO) 4 and its N -oxide 5, having thermal stabilities and energies superior to the analogous derivatives of 5-nitro-2,4-dihydro-3 H -1,2,4-triazole-3-one (NTO). The comparison of properties of the fused triazolones 4 and 8 and their N -oxide derivatives 5 and 9 shows that formation of an N -oxide is an effective strategy which results in an increase of the decomposition temperature, oxygen balance, specific impulse, and detonation properties and in a decrease of the sensitivity of the corresponding energetic material. This work highlights bridged and fused triazolic energetic frameworks with an azo building block providing an alternative structural motif for seeking an applicable high-energy ingredient.more » « less
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null (Ed.)3,6-Diamino-1 H -[1,2,4]triazolo[4,3- b ][1,2,4]triazole ( 1 ) and its energetic salts ( 2–9 ) were designed and synthesized based on a fused-triazole backbone with two C-amino groups as substituents. Their physicochemical and energetic properties were measured or calculated. Among them, compound 1 exhibits superior thermostability ( T d (onset) : 261 °C), surpassing its analogues 3,7-diamino-7 H -[1,2,4]triazolo[4,3- b ][1,2,4]triazole (DATT, 219 °C) and 3,6,7-triamino-7 H -[1,2,4]triazolo[4,3- b ][1,2,4]triazole (TATOT, 245 °C). The differences in thermal stabilities were further investigated by determining the lowest bond dissociation energies (BDE) where a positive correlation between the stability of the molecules and the lowest BDE values is observed. The results show that 1 with the highest value for the lowest BDE has a superior thermostability in comparison to DATT and TATOT. The energetic salts ( 2–9 ) also exhibit remarkable thermal stabilities as well as low impact and friction sensitivities. The fused-triazole backbone 1 H -[1,2,4]triazolo[4,3- b ][1,2,4]triazole with two C-amino groups as substituents is shown to be a promising building block for construction of very thermally stable energetic materials.more » « less
- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/d2ma00406b
