Synthesis of High-Energy, Low-Sensitivity Furazan Tricyclic Energetic Compounds via a Three-Step Reaction

Tricyclic energetic compounds exhibit enhanced conjugated systems relative to bicyclic and monocyclic analogues, rendering them promising candidates for high-performance energetic materials (EMs) due to their superior detonation properties and thermal stability. However, conventional syntheses of tricyclic EMs suffer from lengthy routes. Herein, we report a concise three-step reaction (cyclization, oxidation, and nitration) to construct novel furazan-based tricyclic energy materials. Among the synthesized compounds, 5-(3,5-dinitro-1<i>H</i>-pyrazol-4-yl)-3-(4-nitro-1,2,5-oxadiazol-3-yl)-1,2,4-oxadiazole (<b>4</b>) and 3-(4-nitro-1,2,5-oxadiazol-3-yl)-5-(1-nitro-1<i>H</i>-1,2,4-triazol-3-yl)-1,2,4-oxadiazole (<b>9</b>) achieve an optimal balance between detonation velocity (<i>D</i>_v values of 8922 and 8903 m s^-1, respectively) and thermal stability (<i>T</i>_d values of 275 and 248 °C, respectively), outperforming RDX (<i>D</i>_v = 8795 m s^-1; <i>T</i>_d = 204 °C). Hirshfeld surface and noncovalent interaction (NCI) analyses reveal that extensive intermolecular hydrogen bonds and π-π stacking stabilize the crystal lattice. This robust intermolecular network contributes to their low mechanical sensitivity (IS > 20 J; FS > 324 N). This work provides molecular guidelines for designing advanced tricyclic energetic compounds with practical viability.