Comparative studies on thermal decompositions of dinitropyrazole-based energetic materials

Dinitropyrazole is an important structure for the design and synthesis of energetic mate-rials. In this work, we reported the first comparative thermal studies of two representative di-nitropyrazole-based energetic materials, 4-amino-3,5-dinitropyrazole (LLM-116) and its novel tri-mer derivative (LLM-226). Both the experimental and theoretical results proved the active aromatic N-H moiety would cause incredible variations in the physicochemical characteristics of the ob-tained energetic materials. Thermal behaviors and kinetic studies of the two related dinitropyra-zole-based energetic structures showed that impressive thermal stabilization could be achieved after the trimerization, but also would result in a less concentrated heat-release process. Detailed analysis of condensed-phase systems and the gaseous products during the thermal decomposition processes, and simulation studies based on ReaxFF force field, indicated that the ring opening of LLM-116 was triggered by hydrogen transfer of the active aromatic N-H moiety. In contrast, the initial decomposition of LLM-226 was caused by the rupture of carbon-nitrogen bonds at the diazo moiety.