Synthesis, structure, and the energetic properties of tetraazidopyridine-4-carbonitrile

Tuning Green Explosives through SNAr Chemistry

Reactivity and regioselectivity of SNAr-type fluorine substitution with azide in polyfluorosubstituted nitrobenzenes was studied both theoretically and experimentally. The obtained polyazido-substituted nitrobenzene derivatives were extensively characterized by NMR, IR, HPLC, X-ray, and DFT methods. It was found that the substitution with the azide nucleophile occurs first at the para- and the ortho-positions to the NO2-group and that transazidation reactions also occur here. Thermal decomposition of prepared azidonitrobenzenes was studied both in controlled (kinetic decay) and uncontrolled (explosion) modes. In case of the controlled thermal decomposition of ortho-azidonitrobenzenes, benzofuroxans were found as major products of the reaction unless another azido group was adjacent to the furoxan moiety. The bursting power of azidonitrobenzenes was found to rise gradually with the number of the azide substituents in the aromatic ring.

Highly energetic N-cyano-substituted CL-20 analogues: challenging the stability limits of polynitro hexaazaisowurtzitanes

To design high-energy-density materials of a new level, it is necessary to develop methods for the functionalization of energetic scaffolds, which will make it possible to tune their physicochemical and energetic properties. For this reason, we have elaborated an approach for synthesizing a new series of energetic cage compounds with advanced properties by introducing the N-cyano group into the polynitro hexaazaisowurtzitane framework. The structures of the obtained substances were fully characterized with a combination of methods, including multinuclear (1H, 13C{1H}, 14N, and 15N{1H}) NMR and IR spectroscopy, high-resolution mass spectrometry, X-ray diffraction analysis, electron microscopy and quantum chemical calculations. For the resulting compounds, thermal stability and safety tests were carried out, calorimetric and pycnometric measurements were performed, and the energetic potential was determined by high-temperature chemical equilibrium thermodynamic calculations. The new cyano derivatives have an acceptable density (up to 1.92 g cm-3) and a high enthalpy of formation (up to 2 MJ kg-1), which is 2 times that of the benchmark CL-20. The resistance of the target compounds to friction (up to 220 N) is the highest compared to CL-20 and its known analogues. 4,10-Dicyano-2,6,8,12-tetranitro-2,4,6,8,10,12-hexaazaisowurtzitane of the new series is the most thermally stable (a Tdec of 238 °C) among the known energetic polynitro hexaazaisowurtzitanes and is the first derivative of this family to surpass CL-20 in heat resistance. Moreover, the specific impulse for the novel materials showed an improvement of 6.5-13 s over CL-20.

Exploring a Fused Triazole-Tetrazine Binary CN Material for a Promising Initiating Substance

The pursuit of binary carbon-nitrogen (CN) materials with high density and good thermal stability presents a significant challenge due to the inherent trade-off between high-energy storage and low bond dissociation energy. In this study, we designed and synthesized (S)-1,2-bis(3-azido-1H-1,2,4-triazol-1-yl)diazene (BAzTD) and 2,9-diazidobis([1,2,4]-triazolo)[1,5-d:5',1'-f][1,2,3,4]tetrazine (DAzTT) through a straightforward reaction. Remarkably, DAzTT demonstrated a high density of 1.816 g·cm-3 (at 298 K) and a considerable thermal decomposition temperature of 216.86 °C. These properties outperform those of previously reported binary heterocyclic CN compounds and polyazido heterocyclic compounds. The quantum-chemical methods further substantiated the integral role of aromaticity as the driving force behind this difference. Additionally, the initiation capability of DAzTT was evaluated by a notably low minimum primary charge (MPC = 40 mg), surpassing conventional organic primary explosives, such as commercial 2-diazo-4,6-dinitrophenol (DDNP, MPC = 70 mg). The exceptional priming ability highlights the potential as an environmentally friendly replacement for toxic lead azide. DAzTT sets a new standard for binary CN compounds and provides a valuable precursor for high-nitrogen carbon nitride materials.