A high-density fluorinated energetic material based on an imidazole-fused heterocyclic framework

A new fluorinated energetic material, 1,3,4,6-tetranitro-5,5-bis(trifluoromethyl)hexahydroimidazo[4,5-d]imidazol-2(1H)-one (TNFGU), was designed and synthesized by incorporating two –CF₃ groups into an imidazole-fused heterocyclic skeleton. Single-crystal X-ray diffraction revealed that TNFGU possesses a crystal density of 2.045 g cm⁻³ at 298 K, the highest among neutral CHONF-based energetic compounds. TNFGU exhibits excellent detonation performance, with an experimentally measured detonation velocity of 9224 m s⁻¹ and a corresponding detonation pressure of 40.0 GPa, together with acceptable mechanical sensitivities (IS = 7.5 J, FS > 360 N). Relative to its non-fluorinated analogue, computational analysis indicates a lower maximum electrostatic potential and a larger HOMO–LUMO gap for TNFGU, consistent with its reduced sensitivity. Thermal decomposition analysis further identified HF among the gaseous products, indicating the presence of fluorine-containing species during decomposition. This work illustrates the structural role of –CF₃ substitution in a fused heterocyclic energetic framework and provides valuable guidance for the design of high-density energetic materials with excellent detonation performance and acceptable mechanical sensitivities.