Constructing insensitive heat-resistant energetic materials via hydrazo bridge mediated resonance-assisted hydrogen bonds

Constructing heat-resistant explosives (T_d > 350 °C) has become an important direction in the field of energetic materials. Herein, a new heat-resistant energetic compound, 6,6′-(hydrazine-1,2-diyl)bis(8-nitro-[1,2,4]triazolo[4,3-b]pyridazine-3,7-diamine), namely HDP, was designed and synthesized based on the combined strategies of the hydrazo bridge and resonance-assisted hydrogen bonds (RAHBs). HDP exhibits a striking peak thermal decomposition temperature (T_d = 374.6 °C), which is more outstanding than that of the recently reported hydrazo bridge heat-resistant molecules and even higher than that of the widely used heat-resistant explosives HNS (T_d = 349 °C), TATB (T_d = 360 °C), and PYX (T_d = 377 °C). Moreover, HDP exhibits good mechanical sensitivities (IS = 40 J, FS = 360 N). Theoretical calculations reveal that stronger RAHBs are conducive to the high planarity of molecules and strong interactions in crystals. These findings indicate that the hydrazo bridge mediated RAHBs are an effective strategy to enhance thermal stability and to reduce sensitivity.