Azobis(polynitrophenyl-1,2,5-oxadiazoles)\nas Heat-Resistant\nFriction-Insensitive Energetic Materials

The evolution of energetic materials\nscience presents new challenging\ntasks associated with the creation of advanced technologies for sustainable\ndevelopment of the future. In this work, a set of new heat-resistant\nhigh-energy materials incorporating the polynitrophenyl-1,2,5-oxadiazole\nscaffold enriched with azo/azoxy moieties have been designed and synthesized.\nDue to a smart combination of explosophoric groups and 1,2,5-oxadiazole\nrings, the prepared high-energy substances have excellent thermal\nstability (up to 300 °C), good densities (up to 1.75 g cm<sup>–3</sup>), high enthalpies of formation (340–538 kJ\nmol<sup>–1</sup>), and high combined nitrogen–oxygen\ncontent (63–68%). In-depth structural analysis revealed the\npresence of strong intra- and intermolecular hydrogen bonds in aminodinitrophenyl\nderivatives, which in combination with the small deviation of electrostatic\npotential values explains the low mechanical sensitivity of these\nmaterials. At the same time, trinitrophenyl-1,2,5-oxadiazoles incorporating\nthree adjacent non-coplanar nitro groups demonstrated higher sensitivity\nto impact, albeit retaining complete insensitivity to friction. The\noverall performance of the thus prepared high-energy substances exceeds\nthat of the known heat-resistant explosive hexanitrostilbene. Therefore,\nthe newly synthesized family of energetic polynitrophenyl-1,2,5-oxadiazoles\nprovides a fruitful foundation for the creation of the advanced heat-resistant\nenergetic materials of the future.