Energetic furazan-triazoles with high thermal stability and low sensitivity: Facile synthesis, crystal structures and energetic properties

Crystal stacking has significant implications for the properties of energetic materials, especially molecular stability. A series of furazan-triazole energetic compounds with diverse crystal stacking forms were synthesized through a facile procedure. All new compounds were characterized by NMR spectroscopy, IR spectroscopy, elemental analysis, and differential scanning calorimetry (DSC). Single crystal X-ray diffraction analysis indicated that compounds 2a and 2c show face-to-face stacking, while compounds 3 and 3a exhibit wave-like stacking as a result of their planar furazan-triazole skeleton. Furthermore, on the basis of single-crystal data, noncovalent interactions were analyzed to comprehensively study their structure-property relationships. Compound 2b is highly stable, exhibiting a decomposition temperature of 324 °C, an impact sensitivity of >40 J, and a friction sensitivity of >360 J, thereby demonstrating its potential application as a heat-resistant and insensitive explosive. Meanwhile, 3b with its superior detonation velocity (9114 m s^-1) and pressure (35.8 GPa) and favorable stability (T_d = 226 °C, IS = 20 J, FS = 280 N), exhibits a performance superior to that of RDX. This work provides insights into the combination of molecular design and crystal stacking for generating new energetic materials.