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 H -pyrazol-4-yl)-3-(4-nitro-1,2,5-oxadiazol-3-yl)-1,2,4-oxadiazole ( 4 ) and 3-(4-nitro-1,2,5-oxadiazol-3-yl)-5-(1-nitro-1 H -1,2,4-triazol-3-yl)-1,2,4-oxadiazole ( 9 ) achieve an optimal balance between detonation velocity ( D v values of 8922 and 8903 m s –1, respectively) and thermal stability ( T d values of 275 and 248 °C, respectively), outperforming RDX ( D v = 8795 m s –1; T 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.