Energetic Metal Salts of 3-(5-Amino-1,2,4-oxadiazol-3-yl)-1H-1,2,4-triazol-5-nitramide: Promising Alternatives for Environmentally Friendly Pyrotechnic Components

Abstract

To examine the potential applications of nitrogen-rich heterocycle-based materials, a multifunctional 3-(5-amino-1,2,4-oxadiazol-3-yl)-1H-1,2,4-triazol-5-nitramide ligand with a coplanar configuration was provided, and then a series of its corresponding energetic metal salts were prepared and efficiently characterized. Potassium, cesium, and magnesium salts were further confirmed by using X-ray diffraction techniques. The crystal structures including the coordination modes and packing interactions of these three salts were analyzed. All newly prepared metal salts except EMS-6 exhibited good thermostability (T d > 236 °C) and remarkable insensitivity to mechanical stimulation (sensitivity to impact > 22.5 J, friction > 280 N), suggesting satisfactory safety performance. The constant-volume combustion energy of these eight salts was determined experimentally, and standard molar formation enthalpy (Δ f H m θ ) at 298 K was calculated using Hess's law. Upon their combustion, the three new formulations designed with EMS-1, EMS-7, and EMS-8 presented different shades of red colors, enabling them to be promising candidates for environment-friendly pyrotechnic components.