Efficient Construction of Energetic Materials via Nonmetallic Catalytic Carbon–Carbon Cleavage/Oxime-Release-Coupling Reactions

Theoretical study on intra-molecule interactions in TKX-50

To fully and deeply understand the weak interactions in the gaseous structure of the TKX-50 molecule, two conformations I and II of the TKX-50 molecule confirmed in a crystal cell were optimized at the B3LYP/6-311g(d,p) level in the gas state, and the single point energy of the optimized structure was calculated at the M06-2X/ma-TZVPP level. Analyzing methods for weak interactions such as the interaction region indicator (IRI), topological basin analysis, and the extended transition state-natural orbitals for chemical valence (ETS-NOCV) theory with the help of Multiwfn code were employed to reveal the corresponding intramolecular weak interactions. The results showed that there were 5 kinds of intramolecular weak interaction in both conformations. They are two types of H bond, two types of intra-ring weak interaction, and one type of O-N bond within the molecular fragment containing the bis-tetrazole ring. The combined effect of all these weak interactions holds the bis-tetrazole ring of TKX-50 retaining an almost coplanar configuration. Meanwhile, the strength of these weak interactions is significantly different in conformation I and conformation II. The most obvious difference is that conformation II has a significant H transfer between intramolecular fragments due to the mirror rotation of almost 180° of cations (NH3OH)+ perpendicular to the N-O bond axis thereof as compared to the reference conformation I. This conformational difference not only makes the weak interaction between the two conformations very different but also forms a quasi-covalent bond in conformation II with much larger bonding energy than other H bonds, thus resulting in conformation II having lower electron energy and more stable geometry. In addition, the order of breaking various H bonds in the combustion decomposition process of TKX-50 is deduced by comparing various H bonds.

Anisotropic Impact Sensitivity of Metal-Free Molecular Perovskite High-Energetic Material (C6H14N2)(NH2NH3)(ClO4)3 by First-Principles Study

Density functional theory simulations were carried out to investigate energetic molecular perovskite (C₆H₁₄N₂)(NH₂NH₃)(ClO₄)₃ which was a new type energetic material promising for future application. The electronic properties, surface energy, and hydrogen bonding of (100), (010), (011), (101), (111) surfaces were studied, and the anisotropic impact sensitivity of these surfaces were reported. By comparing the values of the band gaps for different surface structures, we found that the (100) surface has the lowest sensitivity, while the (101) surface was considered to be much more sensitive than the others. The results for the total density of states further validated the previous conclusion obtained from the band gap. Additionally, the calculated surface energy indicated that surface energy was positively correlated with impact sensitivity. Hydrogen bond content of the surface structures showed distinct variability according to the two-dimensional fingerprint plots. In particular, the hydrogen bond content of (100) surface was higher than that of other surfaces, indicating that the impact sensitivity of (100) surface is the lowest.

Tunable 1,2,3-triazole-N-oxides towards high energy density materials: theoretical insight into structure–property correlations

A new family of energetic derivatives based on functionalized bridged 1,2,3-triazole-N-oxides was designed, and their properties as well as comprehensive correlations were investigated.

Novel polynitro azoxypyrazole-based energetic materials with high performance

Novel polynitro azoxypyrazole-based energetic compounds 1,2-bis (4-nitro-1H-pyrazol-5-yl) diazene 1-oxide (3) and 1,2-bis (1,4-dinitro-1H-pyrazol-3-yl) diazene 1-oxide (4) were synthesized from 5-amino-pyrazole-4-carbonitrile by optimized reactions. Their structures were characterized by elemental analysis and single-crystal X-ray diffraction techniques. Compound 3 exhibits high thermal stability (239 °C), low mechanical sensitivity (IS = 22 J, FS = 240 N) and moderate detonation performance (D_v = 8272 m s^-1, P = 28.1 GPa). Compound 4 shows moderate thermal stability (161 °C), decent mechanical sensitivity and higher detonation performance (D_v = 9228 m s^-1, P = 38.7 GPa) compared to that of RDX. These newly developed strategies for constructing novel energetic compounds enrich the content of the ever-expanding energetic materials.

Nitrodiaziridines: Unattainable yet, but Desired Energetic Materials

Using quantum chemical methods and the original technique based on atom-atom potential methods, the molecular and crystal structure simulation of all possible structural forms of nitrodiaziridines were carried out. The possible pathways of thermal decomposition of nitrodiaziridines were modeled, and the most stable forms were identified. Thermodynamic stability, physicochemical characteristics, and detonation properties were also estimated. The obtained results enable a huge potential of the nitrodiaziridine-based compounds as high-energy materials for a variety of applications.

Synthesis and properties of gem-dinitro energetic salts based on 1,2,4-oxadiazole with low impact sensitivity

The compounds in this study are insensitive to impact and more energetic than TNT, giving new insights into gem-dinitro-derived compounds.

Methyl sydnone imine and its energetic salts

First investigation of this new energetic cation, which may greatly expand the range of possible energetic salts available.

A facile synthesis of energetic salts based on fully nitroamino-functionalized [1,2,4]triazolo[4,3-b][1,2,4]triazole

Promising high-energy-density materials: energetic salts based on fully nitroamino-functionalized [1,2,4]triazolo[4,3-b][1,2,4]triazole.

Dual Roles of tert-Butyl Nitrite in the Transition Metal- and External Oxidant-Free Trifluoromethyloximation of Alkenes

By employing tert-butyl nitrite as both nitrogen source and oxidant, the trifluoromethyloximation of alkenes proceeds smoothly in a free-radical process. The developed difunctionalization reaction enables practical and efficient synthesis of a wide range of α-CF₃ ketoximes in moderate yields with excellent regioselectivity. This method features the use of readily available and stable alkenes as substrates and inexpensive CF₃ SO₂ Na as a CF₃ reagent, no involvement of transition metals or external oxidant, and room-temperature conditions. Moreover, a scale-up of the reaction, further transformation of the products into various valuable CF₃ -containing compounds, and removal of the trifluoromethyl group are readily achieved.

Novel strategies for synthesizing energetic materials based on BTO with improved performances

The layer-by-layer assembly of molecules is ubiquitous in nature. Highly ordered structures formed in this manner often exhibit fascinating material properties. A layer hydrogen bonding pairing approach allows the development of tunable energetic materials with targeted properties. A series of unusual energetic compounds based on 1H,1'H-5,5'-bistetrazole-1,1'-diolate (1), such as the salts of 3-amino-1,2,4-triazolium (2), aminoguanidinium (3), and hydrazinium (4), and the cocrystals of 4-amino-1H-pyrazole (5), 2-methylimidazole (6), and imidazole (7), were synthesized using this strategy. The structures of the obtained products 2-7 were fully characterized by elemental analysis, IR spectroscopy, ¹H NMR and ¹³C NMR spectroscopy, and single-crystal X-ray analysis. Their thermal decomposition behavior was studied by differential scanning calorimetry and thermogravimetry. Their mechanical sensitivities and detonation performances were also analyzed in detail. Results show that products 2-7 exhibit higher density, better detonation performances, and more excellent sensitivities than those of the same species of cation salts previously reported.

Synthesis of energetic salts containing three heterocyclic anions by a one-pot condensation reaction

Energetic ionic salts 1 and 2 containing three heterocyclic anions were prepared in a one-pot reaction using 1,3,5-benzenetricarboxaldehyde, aminoguanidine salts, and organic energetic salts (5-nitrotetrazole and 3,5-dinitro-1,2,4-triazole ammonium salt).

Synthesis and performance study of methylene-bridged bis(nitramino-1,2,4-oxadiazole) and its energetic salts

A series of new energetic compounds based on methylene-bridged bis(nitramino-1,2,4-oxadiazole) was synthesized through a simple, safe and efficient route and fully characterized.

Self-assembly of 3D porous architectures from energetic nanoparticles for enhanced energetic performances

3D architectures with porous network of energetic molecules were designed and constructed by introduce a general approach through two-step self-assembly process.

Improving the density and properties of nitrogen-rich scaffolds by the introduction of a C–NO2 group

5,5′-(Nitromethylene)bis(1H-tetrazole) and 5,5′-(2-(nitromethyl)-2H-1,2,3-triazole-4,5-diyl)bis(1H-tetrazole) were synthesized by introducing a C–NO₂ group to increase the density and detonation performance.