Potential High Energy Materials Research Articles

Insensitive High-Energy Density Materials Based on Azazole-Rich Rings: 1,2,4-Triazole N-Oxide Derivatives Containing Isomerized Nitro and Amino Groups.

It is an arduous and meaningful challenge to design and develop new energetic materials with lower sensitivity and higher energy. How to skillfully combine the characteristics of low sensitivity and high energy is the key problem in designing new insensitive high-energy materials. Taking a triazole ring as a framework, a strategy of N-oxide derivatives containing isomerized nitro and amino groups was proposed to answer this question. Based on this strategy, some 1,2,4-triazole N-oxide derivatives (NATNOs) were designed and explored. The electronic structure calculation showed that the stable existence of these triazole derivatives was due to the intramolecular hydrogen bond and other interactions. The impact sensitivity and the dissociation enthalpy of trigger bonds directly indicated that some compounds could exist stably. The crystal densities of all NATNOs were larger than 1.80 g/cm3, which met the requirement of high-energetic materials for crystal density. Some NATNOs (9748 m/s for NATNO, 9841 m/s for NATNO-1, 9818 m/s for NATNO-2, 9906 m/s for NATNO-3, and 9592 m/s for NATNO-4) were potential high detonation velocity energy materials. These study results not only indicate that the NATNOs have relatively stable properties and excellent detonation properties but also prove that the strategy of nitro amino position isomerization coupled with N-oxide is an effective means to develop new energetic materials.

The Conversion-Type Selenides as Potential High-Energy Cathode Materials for Mg-Based Batteries: A Review

The Conversion-Type Selenides as Potential High-Energy Cathode Materials for Mg-Based Batteries: A Review

Polymerization of nitrogen in two theoretically predicted high-energy compounds ScN6 and ScN7 under modest pressure

Materials under high pressure usually exhibit unique chemical and physical properties. Polynitrogen compounds have received widespread attention as potential high energy density materials. This paper uses CALYPSO crystal structure prediction method to study the structures of ScN6 and ScN7 in 0–100 GPa. Theoretical calculations show that ScN6 is thermodynamically stable above 80 GPa, while ScN7 is thermodynamically stable from 30 GPa to 90 GPa. Furthermore, ScN7 is metastable under ambient conditions, demonstrating that it can be quenched to ambient conditions after high pressure synthesis. The P -ScN6 is a three-dimensional extended fold multi-nitrogen network, and the P -ScN7 contains a five-membered ring and a curved N4 molecular unit. Both P -ScN6 and P -ScN7 contain a lot of N–N single bonds and N=N double bonds. The energy densities of P -ScN6 and P -ScN7 are 3.97 kJ g−1 and 3.12 kJ g−1, respectively. The detonation velocity and detonation pressure of the P -ScN6 phase and P -ScN7 phase are also higher than that of TNT. Excellent energy storage properties and detonation performance show that they can be used as potential high-energy materials. These results opened up a new way for the synthesis of nitrogen-rich compounds.

An electrochemical multicomponent reaction toward C-H tetrazolation of alkyl arenes and vicinal azidotetrazolation of alkenes.

The widespread use of tetrazoles in medicine, biology, and materials science continuously promotes the development of their efficient and selective syntheses. Despite the prosperous development of multicomponent reactions, the use of the most abundant and inexpensive chemical feedstocks, i.e., alkanes and alkenes, toward the preparation of diverse tetrazoles remains elusive. Herein, we developed an electrochemical multicomponent reaction (e-MCR) for highly efficient and selective C-H tetrazolation of alkyl arenes. When applied to alkenes, the corresponding vicinal azidotetrazoles were readily obtained, which were further demonstrated to be versatile building blocks and potential high-energy materials.

A heat-resistant and insensitive energetic material based on the pyrazolo-triazine framework

One of the major challenges in the field of energetic materials is to develop explosive molecules with high detonation performances and low mechanical sensitivity. In this work, a heat-resistant and insensitive energetic compound 4-amino-7-nitro-5H-pyrazolo [4,3-d][1,2,3]triazine-2-oxide (3) was designed and prepared. It was identified and characterized using X-ray single-crystal diffraction, IR spectroscopy, NMR spectroscopy, mass spectrometry, thermogravimetry, differential scanning calorimetry (TG-DSC), and elemental analysis. This novel energetic compound exhibits good detonation performances (Dv ​= ​8731 ​m ​s−1, P ​= ​31.20 ​GPa), low mechanical sensitivities (IS ​> ​20 ​J, FS ​> ​360 ​N), and excellent thermal stability (Td ​= ​291 ​°C), suggesting that compound 3 may serve as a potential high-energy and insensitive material.

High-energy materials based on 1H-tetrazole and furoxan: Molecular design and screening

Forty-eight energetic compounds by incorporating -N3, -NHNH2, -C(NO2)3, -NO2, -CH(NO2)2, -NHNO2, -NH2, and -ONO2 groups to bridged 1H-tetrazole and furoxan (1,2,5-oxadiazole) framework were designed. Their electronic structures, heats of formation (ΔHgas298.15K), detonation properties, molecular stabilities, and electrostatic potential were systematically investigated by density functional theory. The results showed that the introduction of -N=N- and -N=N(O)- bridges can better increase ΔHgas298.15K, -CH(NO2)2, -C(NO2)3, -NO2, and -ONO2 groups have the better effect on increasing the density of compounds, -N3, -NH2, and -NHNH2 groups can reduce the sensitivity of compounds, and compounds introduced with -NHNO2 group have higher detonation performance and ideal sensitivity. Considering the detonation properties, four compounds (E7, G3, G7, and H6) were selected as potential high-energy materials because they have higher detonation properties than CL-20. Compared to the traditional energetic compound RDX, all designed compounds have similar or better oxygen balance, density, and detonation properties. Among them, the maximum detonation velocity, detonation pressure, and density can reach 9.61 km s−1 (G5), 43.41 GPa (I6), and 2.06 g cm−3 (G6).

New Cadmium-Nitrogen Compounds at High Pressures.

A systematic high-pressure study of the CdNx (x = 2, 3, 4, 5, and 6) system is performed by using the first-principles calculation method in combination with the particle swarm optimization algorithm. We proposed four stable high-pressure phases (P4mbm-CdN2, Cmmm-CdN4, I4̅2d-CdN4, and C2/c-CdN5) and one metastable high-pressure phase (C2/m-CdN6), for which the structural frames are composed of a diatomic quasi-molecule N2, standard armchair N-chain, S-type bent armchair N-chain, zigzag-antizigzag N-chain, and N14 network structure. Among them, the novel zigzag-antizigzag N-chain and N14 network structure are reported for the first time. More importantly, Cmmm-CdN4 and C2/m-CdN6 possess high stability under ambient conditions, which may be quenched to ambient conditions once they are synthesized at high-pressure conditions. The high decomposition energy barrier (1.14 eV) results in a high decomposition temperature (2500 K) of Cmmm-CdN4, while a low decomposition energy barrier (0.19 eV) results in a mild decomposition temperature (500 K) of C2/m-CdN6. The high energy density and outstanding explosive performance make Cmmm-CdN4, I4̅2d-CdN4, C2/c-CdN5, and C2/m-CdN6 potential high-energy materials. The electronic structure analyses show that these predicted high-pressure structures are all metallic phases, and the N-N and Cd-N bonds are the strong covalent and ionic bond interactions, respectively. The charge transfer from the Cd atom plays an important role in the stability of the proposed structures.

Synthesis and characterization of new potential high-energy materials based on fullerene soot nanoparticles and nitroaryl diazonium ions

In this study, synthesis and characterization of new potential high-energy materials based on fullerene soot nanoparticles and nitroaryl diazonium ions were reported. Synthesis was carried out using reaction of fullerene soot with nitroaryl diazonium ions in acetonitrile or solvent free under thermal or microwave-assisted conditions. The nitroaryl diazonium ions were prepared insitu using reactions of 2-nitroaniline, 4-nitroaniline and 2,4-dinitroaniline with isoamyl nitrite. The spectroscopic and instrumental analytical methods such as Fourier transform infrared (FT-IR), Raman, ultraviolet–visible (UV–Vis), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray (EDX), elemental map and thermogravimetric analysis (TGA) were used to characterize the fullerene soot functionalized with nitroaryl groups. The differential thermal analysis (DTA) was applied to verify the energy releasing property of these compounds. The obtained results clearly confirmed the successful functionalization of fullerene soot nanoparticles by nitroaryl diazonium ions.

1,2,5-Oxadiazole-1,2,3,4-tetrazole-based high-energy materials: molecular design and screening

Various 1,2,5-oxadiazole-1,2,3,4-tetrazole-based high-energy materials were designed and their properties investigated. Their heat of formation, detonation properties, and thermal stability were calculated on the basis of isodesmic reactions, Kamlet-Jacobs equation, and bond dissociation energy, respectively. The results showed that all designed compounds possess high positive heat of formation, and the –N=N–/–N3 substituents were found to be the most effective for improving the heat of formation. The trend of changes in density, detonation pressure, and detonation velocity was almost identical in all compounds, which suggests that density was key to the determination of detonation properties. In view of bond dissociation energy, the –CN/–NH2 substituents improved the thermal stability of the designed compounds, while the other substituents/bridges decreased the stability to some extent. Considering the detonation properties and thermal stability, six compounds (C7, D3, D7, F7, G7, and H7) were selected as potential high-energy materials because they exhibited higher detonation properties and thermal stability than 1,3,5-trinitro-1,3,5-triazinane (RDX). Finally, electronic structures (such as distribution of frontier molecular orbitals and electrostatic potential) of the selected compounds were simulated to obtain detailed information about the electronic structures of the screened compounds.

Functionalized Tetrazole Energetics: A Route to Enhanced Performance

AbstractTetrazoles are a class of heterocyclic compounds. Many tetrazole derivatives have been studied extensively as potential high energy materials. Compared with other nitrogen‐rich heterocycles, most tetrazole‐based heterocycles demonstrate superior properties due to the higher density and heat of formation levels. A large variety of advanced energetic materials have been achieved based on the combination of tetrazole moieties with a collection of bridges. This review is an overview of the recent developments of energetic tetrazole structures, and where possible, information such as the synthetic methods, and physical and detonation properties are provided. Given the synthetic opportunities and outstanding properties, energetic materials based on tetrazole structures are undoubtedly promising candidates for the development of highly energetic materials for civilian or military applications.

Novel 4,5‐Dinitro‐N,N′‐dialkylimidazolium Cations as Candidates for High‐energy Materials

In the synthesis of energetic ionic liquids (EILs), the quaternization of dinitroimidazoles remains a challenging task due to their reduced nucleophilicity. In this study, two new EILs precursors, 3‐ethyl‐1‐methyl‐4,5‐dinitro‐1H‐imidazol‐3‐ium tetrafluoroborate (1) and 1,3‐diethyl‐4,5‐dinitro‐1H‐imidazol‐3‐ium tetrafluoroborate (2) were obtained via the alkylation of 1‐methyl‐4,5‐dinitro‐1H‐imidazole and 4,5‐dinitro‐1H‐imidazole using Meerwein's reagents, respectively. The 4,5‐dinitroimidazolium cations are expected to be applied for new insensitive high‐energy materials (HEMs) via an anion metathesis reaction with energetic anions. Two new EILs, 3‐ethyl‐1‐methyl‐4,5‐dinitro‐1H‐imidazol‐3‐ium 2,4,5‐trinitroimidazol‐1‐ide (3) and 1,3‐diethyl‐4,5‐dinitro‐1H‐imidazol‐3‐ium 2,4,5‐trinitroimidazol‐1‐ide (4), were obtained as potential HEMs via the anion metathesis reaction with 2,4,5‐trinitroimidazol‐1‐ide. Although some improvements in the thermal properties are desired, compound 3 showed the promising properties as a new insensitive HEM because of its excellent insensitivity and more powerful explosive performance than those of 2,4,6‐trinitrotoluene (TNT).

Novel energetic coordination compounds based on 3,5-dinitro-4-oxylpyrazolate ligand with excellent thermostability and low sensitivity

In recent years, the discovery of novel energetic coordination compounds (ECCs) with high energy performance and low sensitivity is very desirable but highly challenging. Nitroazole-based ECCs have attracted a lot of attention in this area owing to their prominent advantages including excellent energy performance and good thermostability. Herein, three new ECCs based on 3,5-dinitro-4-oxylpyrazolate (DNOP) ligand were synthesized, characterized and evaluated as potential high-energy materials. Their structures and coordination mode were confirmed by the single crystal X-ray diffraction analysis. Thermal stability, sensitivities and energy performance were measured and studied in detail. The results suggest that as-prepared new ECCs are classified as “less sensitive” energetic materials exhibiting relative low sensitivity (IS = 14–18 J, FS = 240–324 N). Additionally, these new ECCs exhibit excellent thermal stability with high decomposition temperature beyond 290 °C. Inheriting the significant energy performance of 3,5-dinitro-4-oxylpyrazolate ligand, they could also possess attractive energy property.

Pressure-Stabilized New Phase of CaN4**Supported by the National Key Technology Research and Development Program of China under Grant No. 2018YFA0305900, the National Natural Science Foundation of China under Grant Nos. 11634004, 51320105007, 11604116 and 51602124, and the Program for Changjiang Scholars and Innovative Research Team in University of Ministry of Education of China under Grant No. IRT1132.

We propose a new CaN4 high pressure structure with the P21/m space group. The P21/m-CaN4 structure is constituted by the infinite armchair N-chain. The dynamical stability and mechanical stability are verified by the calculations of phonon dispersion curves and elastic constants. The enthalpy difference calculation shows that the P21/m phase is more stable than the reported P41212 phase. The advantaged properties of P21/m-CaN4, such as high nitrogen content (58.3%) and low polymerization pressure (18.3 GPa), allow it to be a potential high energy material. Band structure calculation shows that the P21/m-CaN4 structure is a metallic phase. The nonpolar covalent single N–N bond is a sigma bond. The charge transfer between the Ca and N atoms results in an ionic bond interaction.

Novel high-energy ionic molecules deriving from new monovalent and divalent 4-oxyl-3,5-dinitropyrazolate moieties

ABSTRACT In recent years, the exploration of a practical strategy for novel energetic molecules with high energy and low sensitivity is very desirable but highly challenging. Novel ionic energetic molecules have attracted much attention in this area due to their prominent advantages including low sensitivities, high thermal stability, and excellent energy performances. Herein, five different ionic energetic molecules based on new monovalent and divalent 4-oxyl-3,5-dinitropyrazolate moieties with enhanced oxygen balance have been synthesized, characterized and evaluated as potential high-energy materials. Thermal stability, sensitivities and energy output test were measured and studied in detail. The heats of formation and energetic parameters were calculated by using Gaussian 09 suite of programs and EXPLO 5 code. The results suggest that all as-prepared new molecules exhibit good thermal stability with high decomposition temperature (3, 231°C; 5, 160°C; 6, 185°C; 7, 180°C; 8, 213°C), and relative low sensitivity (IS > 20 J, FS = 324 N). Inheriting the significant oxygen content of monovalent and divalent 4-oxyl-3,5-dinitropyrazolate moieties, they also possess good energy properties (v D = 8238 ~ 9208 m s−1, P = 26.8 ~ 36.7 GPa, V o = 481.8 ~ 959.4 L kg−1), which make them competitive high-energy materials.

Chlorates and perchlorates as potential high-energy materials: chlorate- and perchlorate-substituted methanes

The structures and properties of thirty-three of the thirty-four possible chlorato-Cl-, chlorato-O- and perchlorato-derivatives of methane have been computed using the range-separated hybrid generalized gradient approximation density functional method ωB97X-D with the 6-311+G(2d,p) basis set. These results indicate that the chlorato-O-substituent confers more stability to a molecule than does the chlorato-Cl-substituent; the perchlorato-substituent is approximately intermediate in this regard when decomposition energies are calculated. The C–Cl bond lengths in the chlorato-Cl-substituents generally elongate and the C–O distances in the chlorato-O- and perchlorato-substituents tend to shorten as the number of chlorate/perchlorate substituents increases. In addition, as the C–O bond shortens, the CO–Cl bond lengthens. The calculated Mulliken and Löwdin bond orders for these bonds exhibit the opposite of the trends exhibited by the bond lengths, as expected: As the bond lengthens, the bond order decreases, and vice versa. The single molecule that could not be optimized as a stable methane derivative, (chlorato-Cl-)tris(chlorato-O-)methane, rearranged during all optimization attempts to an isomer of the neutral Cl2O5 molecule and a hitherto unknown molecule, bis(chlorato-O-)carbonyl, (O2ClO)2C=O.

Computational assessment of energetic salts containing 7H-[1,2,4]triazolo[4,3-b][1,2,4]triazole

The computational design of energetic salts based on 3,6,7-triamino-7H-[1,2,4]triazolo[4,3-b][1,2,4]triazol-2-ium (cation A) and 3,7-diamino-7H-[1,2,4]triazolo[4,3-b][1,2,4]triazol-2-ium (cation B) is described. Selective energetic anions have been combined with these cations to tune the performance parameters. All the designed salts (A1–11 and B1–11) exhibited reasonable densities ranging from 1.54 to 1.85 g/cm $$^{3}$$ , and positive heats of formation between 301 kJ/mol and 854 kJ/mol. The detonation properties for the A1–11 and B1–11 salts were computed using Kamlet–Jacobs method, and the corresponding values were found in the ranges of 6.12 km/s to 8.79 km/s and 15.12 GPa to 34.84 GPa. Admirable energetic performance and reasonable sensitivity indicate A4 and B4 as promising energetic salts. SYNOPSIS The computational design of energetic salts based on 3,6,7-triamino-7H-[1,2,4]triazolo[4,3-b][1,2,4]triazol-2-ium and 3,7-diamino-7H-[1,2,4]triazolo[4,3-b][1,2,4]triazol-2-ium is described. All the salts possess positive HOF range from 301 to 854 kJ/mol. Among the designed salts, two salts (A4 and B4) exhibit superior performance, and efforts can be made for their development as potential high energy materials (HEMs).

Stability, Elastic Properties, and Deformation of LiBN2: A Potential High-Energy Material.

Searching for high-energy-density materials is of great interest in scientific research and for industrial applications. Using an unbiased structure prediction method and first-principles calculations, we investigated the phase stability of LiBN2 from 0 to100 GPa. Two new structures with space groups P4̅21 m and Pnma were discovered. The theoretical calculations revealed that Pnma LiBN2 is stable with respect to a mixture of 1/3Li3N, BN, and 1/3N2 above 22 GPa. The electronic band structure revealed that Pnma LiBN2 has an indirect band gap of 2.3 eV, which shows a nonmetallic feature. The Pnma phase has a high calculated bulk modulus and shear modulus, indicating its incompressible nature. The microscopic mechanism of the structural deformation was demonstrated by ideal tensile shear strength calculations. It is worth mentioning that Pnma LiBN2 is dynamically stable under ambient conditions. The decomposition of this phase is exothermic, releasing an energy of approximately 1.23 kJ/g at the PBE level. The results provide new thoughts for designing and synthesizing novel high-energy compounds in ternary systems.

Density Functional Theory Calculations on Nitrated Boroxines as Possible High Energy-Density Materials

Density functional theory calculations were performed on a series of nitroboroxine molecules (cyclo-[BO]3-[NO2]xH3-x, x = 1 – 3) to determine their thermodynamic properties and assess them as potential high energy materials. Minimum-energy geometries of four boroxine molecules were determined, along with their normal modes of vibration. Analysis of the energies of the molecules and their possible decomposition and combustion products suggests an energy contact comparable to that of TNT.

The effect of nitro groups on the structures and energetic properties of the derivatives composed of TATB and cubane

Based on the successful experience of synthesis of the TATB (1, 3, 5-triamino-2, 4, 6-trinitrobenzene) and cubane, we propose to consider their nitro derivatives combined by C–N bond as a series of high energy density compounds. First principles molecular orbital calculations have been used to investigate the structural and energetic properties, including the heat of formation, density, detonation performance, and impact sensitivity. Natural bond orbital analysis was carried out to investigate the influence of substituents on the electron delocalization. The results implied that the inclusion of nitro group will decrease the stability of cage skeleton and weaken the C–NO2 bond. The calculated heats of formation, density, detonation velocity, and detonation pressure are positive and large. The results revealed that two of five derivatives have the close performance and sensitivity to those of CL-20, indicating that they may be explored as new potential high energy materials. Leave them with the notable value to dig out.

Binary mixed carbon, silicon, nitrogen, and phosphorus cubane derivatives as potential high energy materials

Gas phase standard state (298.15K, 1atm) enthalpies of formation (ΔfH°(g)) were calculated at the G4 composite method level of theory for the parent and binary mixed carbon, silicon, nitrogen, and phosphorus cubane derivatives. Increasing nitrogen content increases the ΔfH°(g) for the carbon–nitrogen, nitrogen–phosphorus, and silicon–nitrogen binary cubanes, with the opposite ΔfH°(g) trend for increasing phosphorus content within the carbon–phosphorus, nitrogen–phosphorus, and silicon–phosphorus derivatives. Varying carbon/silicon content in the carbon–silicon cubanes results in no general trends for ΔfH°(g). Analogous ΔfH°(g) structure–property trends were found among the parent and binary mixed carbon, silicon, nitrogen, and phosphorus tetrahedrane derivatives. Cubanoid isomerization enthalpies within the homolog groups having more than one isomer vary widely with atomic composition and substitution patterns. Mass normalized enthalpies of combustion (ΔcombH°(g)) of the binary mixed cubanoids are superior to that of common explosives. The binary mixed carbon, silicon, nitrogen, and phosphorus cubane derivatives are predicted to display potentially tunable thermodynamic properties for high energy materials depending on the atom identities and relative positions.