Theoretical calculation of nitro-1-(2,4,6-trinitrophenyl)-1H-azoles energetic compounds

In order to study the properties of new energetic compounds formed by introducing nitroazoles into 2,4,6-trinitrobezene, the density, heat of formation and detonation properties of 36 nitro-1-(2,4,6-trinitrobenzene)-1H-azoles energetic compounds are studied by density functional theory, and their stability and melting point are predicted. The results show that most of target compounds have good detonation properties and stability. And it is found that nitro-1-(2,4,6-Trinitrophenyl)-1H-pyrrole compounds and nitro-1-(2,4,6-trinitropenyl)-1H-Imidazole compounds have good thermal stability, and their weakest bond is C-NO2 bond, the bond dissociation energy of the weakest bond is 222 kJ mol-1-238 kJ mol-1 and close to TNT (235 kJ mol-1). The weakest bond of the other compounds may be the C-NO2 bond or the N-N bond, and the strength of the N-N bond is related to the nitro group on azole ring.

Synthesis of Energetic 7-Nitro-3,5-dihydro-4H-pyrazolo[4,3-d][1,2,3]triazin-4-one Based on a Novel Hofmann-Type Rearrangement

Rearrangement reactions are efficient strategies in organic synthesis and contribute enormously to the development of energetic materials. Here, we report on the preparation of a fused energetic structure of 7-nitro-3,5-dihydro-4H-pyrazolo[4,3-d][1,2,3]triazin-4-one (NPTO) based on a novel Hofmann-type rearrangement. The 1,2,3-triazine unit was introduced into the fused bicyclic skeleton from a pyrazole unit for the first time. The new compound of NPTO was fully characterized using multinuclear NMR and IR spectroscopy, elemental analysis as well as X-ray diffraction studies. The thermal behaviors and detonation properties of NPTO were investigated through a differential scanning calorimetry (DSC-TG) approach and EXPLO5 program-based calculations, respectively. The calculation results showed similar detonation performances between NPTO and the energetic materials of DNPP and ANPP, indicating that NPTO has a good application perspective in insensitive explosives and propellants.

Computational Design of High Energy RDX-Based Derivatives: Property Prediction, Intermolecular Interactions, and Decomposition Mechanisms

A series of new high-energy insensitive compounds were designed based on 1,3,5-trinitro-1,3,5-triazinane (RDX) skeleton through incorporating -N(NO2)-CH2-N(NO2)-, -N(NH2)-, -N(NO2)-, and -O- linkages. Then, their electronic structures, heats of formation, detonation properties, and impact sensitivities were analyzed and predicted using DFT. The types of intermolecular interactions between their bimolecular assemble were analyzed. The thermal decomposition of one compound with excellent performance was studied through ab initio molecular dynamics simulations. All the designed compounds exhibit excellent detonation properties superior to 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20), and lower impact sensitivity than CL-20. Thus, they may be viewed as promising candidates for high energy density compounds. Overall, our design strategy that the construction of bicyclic or cage compounds based on the RDX framework through incorporating the intermolecular linkages is very beneficial for developing novel energetic compounds with excellent detonation performance and low sensitivity.

Design and Selection of Pyrazolo[3,4-d][1,2,3] Triazole-based High-energy Materials

In this study, we design a series of bridged energetic compounds based on pyrazolo[3,4-d][1, 2, 3]triazole to screen potential energetic materials with excellent detonation properties and acceptable sensitivities. The electronic structures, heats of formation, detonation velocity, detonation pressure, and impact sensitivity of the designed compounds were calculated using density functional theory. The results showed that the designed compounds have high positive heats of formation in the range of 1035.4 (A7) to 2851.4 kJ mol−1 (D2). Moreover, the designed compounds have high crystal densities and heats of detonation, which significantly enhance detonation pressures and velocities. The detonation pressures and velocities are in the ranges of 6.23 (A1) to 9.65 km s−1 (D3) and 15.7 to 43.9 GPa (E8), respectively. The impact sensitivity data also suggest that the designed compounds have impact sensitivities in an acceptable range. Considering detonation pressures, detonation velocities, and impact sensitivities, six compounds (C3, C5, D3, D5, E3, and F3) were screened as potential materials with high energy density, excellent detonation properties, and low impact sensitivities. Finally, the electronic structures of the screened compounds were simulated to provide further understanding on the physicochemical properties of these compounds.

Theoretical design of high-nitrogen energetic molecules: Performance prediction of pentazole-based derivatives

High nitrogen energetic compounds have always been a hot spot in energetic materials. In this work, we provide a new approach for the design of promising energetic molecules containing pentazole. Attractive energetic compounds include 5-amino-3-nitro-1H-1,2,4-triazole (ANTA) and 5-nitro-1,2,4-triazol-3-one(NTO) are used to effectively combine with pentazole to form a series of pentazole derivatives. Then, the NH2, NO2 or NF2 groups were introduced into the system to further adjust the property. Herein, the structures and densities of designed compounds as well as the heats of formation, detonation properties and impact sensitivities were predicted based on density functional theory (DFT). The results show that all ten designed molecules have excellent densities (1.81 g/cm3 to 1.97 g/cm3) and high heats of formation (621.66 kJ/mol to 1374.63 kJ/mol). Furthermore, detonation performances of compounds A3 (P = 41.16 GPa and D = 9.45 km/s) and A4 (P = 43.90 GPa and D = 9.69 km/s) are superior to 1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), and lower impact sensitivity than HMX. It exhibited that they could be taken as promising candidates of high-energy density materials. This work provides a worthy way to explore the energetic compounds with excellent performance based on pentazole.

High-pressure new phase of AgN3

The structural evolutionary behaviors of AgN3 have been studied by using the particle swarm optimization structure search method combined with the density functional theory. One stable high-pressure metal polymeric phase with the [Formula: see text] space group is suggested. The enthalpy difference analysis indicates that the Ibam-AgN3 phase will transfer to the I4/mcm-AgN3 phase at 4.7 GPa and then to the [Formula: see text]-AgN3 phase at 24 GPa. The [Formula: see text]-AgN3 structure is composed of armchair–antiarmchair N-chain, in which all the N atoms are sp2 hybridization. The inherent stability of the armchair–antiarmchair chain and the anion–cation interaction between the N-chain and Ag atom induce a high stability of the [Formula: see text]-AgN3 phase, which can be captured at ambient conditions and hold its stable structure up to 1400 K. The exhibited high energy density (1.88 KJ/g) and prominent detonation properties ([Formula: see text] Km/s; [Formula: see text] GPa) of the [Formula: see text]-AgN3 phase make it a potentially high energy density material.

Theoretical Research on Cage-like Oxadiazole-based Energetic Compounds and Its Derivatives

In this manuscript, we reported the design and prediction of two oxadiazole-based cage-like molecules and their derivatives using density function theory (DFT). The heats formation and detonation properties were calculated using Hess’s law and Kamlet-Jacobs equations with B3PW91 method. The molecular stability and geometry were analyzed using M06-2X method and molecular crystal structures were predicted based on Monte Carlo simulation, while chemical reactive sites were judged using PBE0 method based on Fukui function. The theoretical calculation result proved that the designed molecules exhibit ideal symmetric cage-like geometry and show superior physicochemical and detonation properties. Compared with traditional energetic materials, the designed molecules display more positive solid heats formation and lower sensitivity. The designed molecules could be considered as promising HEDM candidates with potential synthesis and application value.