Series of AzTO-Based Energetic Materials: Effect of Different π-π Stacking Modes on Their Thermal Stability and Sensitivity

Mechanochemical Nitration Studies of Aminotriazole Compounds

In order to promote the green development of the nitration process of energy-containing materials and to reduce the environmental pollution and resource waste caused by the traditional nitration reaction. We used a solvent-free mechanochemical reaction to nitrify 3-amino-1,2,4-triazole and 3,5-diamino-1,2,4-triazole and successfully obtained 3-nitro-1,2,4-triazole and 3,5-dinitro-1,2,4-triazole by using sodium nitrite and molybdenum trioxide as catalysts. Several parameters affecting the nitration reaction were explored, and the structures of the products were analyzed by combining Gaussian, Multiwfn, and other computational software; also, single crystals of 3,5-dinitro-1,2,4-triazole sodium salt were cultivated and analyzed for their crystal structure and surface properties, and their copper and lead salts were obtained by reacting with metal salts. The present work provides a new idea for the development of green nitration of energy-containing materials.

Combining the advantages of 1,3,4-oxadiazole and tetrazole enables achieving high-energy insensitive materials

Combining the advantages of energetic heterocycles to achieve high-energy insensitive explosives is a significant challenge. Herein, based on high-energy tetrazole rings and highly stable 1,3,4-oxadiazole rings, a series of novel nitrogen rich energetic compounds 5-9 were successfully constructed. The related compounds were fully characterized by EA, FT-IR, NMR, DSC, and MS, and compounds 6-9 were further confirmed by X-ray single crystal diffraction. Among them, the energetic ion salts 6-8 show high thermal stability (Tdec > 250 °C) and low mechanical sensitivity (IS > 40 J, FS > 360 N), as well as good energy properties (7552-8050 m s-1, 19.4-23.3 GPa). In particular, the azo compound 9 exhibits competent comprehensive performances (Tdec = 226.2 °C, D = 8502 m s-1, P = 28.9 GPa, IS = 32 J, FS = 320 N). These results suggest that the strategy of integrating tetrazole and 1,3,4-oxadiazole and employing an azo structure as a bridging unit are effective approaches to construct high-energy insensitive materials.

Thermal Reactivity of High-Density Hybrid Hexahydro-1,3,5-trinitro-1,3,5-triazine Crystals Prepared by a Microfluidic Crystallization Method

In this paper, the two-dimensional (2D) high nitrogen triaminoguanidine-glyoxal polymer (TAGP) has been used to dope hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) crystals using a microfluidic crystallization method. A series of constraint TAGP-doped RDX crystals using a microfluidic mixer (so-called controlled qy-RDX) with higher bulk density and better thermal stability have been obtained as a result of the granulometric gradation. The crystal structure and thermal reactivity properties of qy-RDX are largely affected by the mixing speed of the solvent and antisolvent. In particular, the bulk density of qy-RDX could be slightly changed in the range from 1.78 to 1.85 g cm^-3 as a result of varied mixing states. The obtained qy-RDX crystals have better thermal stability than pristine RDX, showing a higher exothermic peak temperature and an endothermic peak temperature with a higher heat release. E_a for thermal decomposition of controlled qy-RDX is 105.3 kJ mol^-1, which is 20 kJ mol^-1 lower than that of pure RDX. The controlled qy-RDX samples with lower E_a followed the random 2D nucleation and nucleus growth (A2) model, whereas controlled qy-RDX with higher E_a (122.8 and 122.7 kJ mol^-1) following some complex model between A2 and the random chain scission (L2) model.

New Method for Predicting the Enthalpy of Salt Formation

A new efficient method for calculating the enthalpies of salt formation is proposed. The method is based on a fundamentally new cocrystal model, consisting of a mixture of cations and anions and a "quasi-salt" of neutral components, in fact, of the salt itself, and the enthalpy of formation is calculated as the average value between the enthalpies of formation of these two structural components. Unlike correlation and additive schemes, this method is based on the construction of a real physical model of a salt crystal, for which the molecular geometry of the ions and neutral salt components is preliminarily optimized by quantum chemistry methods. Further, based on the obtained data, the initial models of crystal lattices in the statistically most probable structural classes are constructed with their subsequent optimization by the method of Atom-Atom potentials. For a number of compounds of various chemical classes, the effectiveness of the method for estimating the enthalpy of salts is shown, which surpasses the known methods in terms of calculation accuracy.

Recent Progress on Synthesis, Characterization, and Performance of Energetic Cocrystals: A Review

In the niche area of energetic materials, a balance between energy and safety is extremely important. To address this "energy-safety contradiction", energetic cocrystals have been introduced. The investigation of the synthesis methods, characteristics, and efficacy of energetic cocrystals is of the utmost importance for optimizing their design and development. This review covers (i) various synthesis methods for energetic cocrystals; (ii) discusses their characteristics such as structural properties, detonation performance, sensitivity analysis, thermal properties, and morphology mapping, along with other properties such as oxygen balance, solubility, and fluorescence; and (iii) performance with respect to energy contents (detonation velocity and pressure) and sensitivity. This is followed by concluding remarks together with future perspectives.

Synthesis and characterization of thermally stable energetic complexes with 3,5-diaminopyrazolone-4-oxime as a nitrogen-rich ligand

Two thermally stable complexes based on DAPO were synthesized. The thermal decomposition temperatures were 287 °C and 344 °C, respectively. The detonation properties of the complexes were excellent with good detonation velocity and detonation pressure superior to that of TNT.

Strong intermolecular interaction induced methylene-bridged asymmetric heterocyclic explosives

Methylene-bridged asymmetric heterocyclic explosives were designed and synthesized to attempt the possibility of realizing energetic materials with high-energy and adequate sensitivity.

Energetic metal–organic frameworks achieved from furazan and triazole ligands: synthesis, crystal structure, thermal stability and energetic performance

Energetic metal–organic frameworks (EMOFs) have witnessed increasing development and been proved as promising candidates for new high energy density materials (HEDMs).