Tuning energy properties via N-NH₂ strategy: Construction of two isomeric energetic compounds based on nitro-substituted pyrazoles

The N -site functionalization strategy of nitrogen-rich heterocycles has attracted considerable research attention due to its crucial role in achieving structural diversity and outstanding performance of high-energy compounds. However, research on isomerism-guided N -functionalized heterocycles is still limited thereby impeding a thorough understanding of their structure-property relationships. In this work, two energetic compounds, 3-azido-4,5-dinitropyrazole-1-amine ( 3-ADNP ) and 4-azido-3,5-dinitropyrazole-1-amine ( 4-ADNP ), with identical chemical structures were designed and synthesized based on the N -NH₂ synthesis strategy. The isomers 3-ADNP ( D _v: 9306 m s⁻¹; P : 38.3 GPa) and 4-ADNP ( D _v: 9375 m s⁻¹; P : 38.9 GPa) exhibit comparable and superior detonation performance compared to RDX. In addition, they exhibit consistency in density and sensitivity, but show significant differences in thermal stability. Specifically, 3-ADNP shows no melting point, whereas 4-ADNP has a melting point of 116.4 °C. The decomposition temperatures are 138.4 °C for 3-ADNP and 156.7 °C for 4-ADNP . Crystal structure analysis and theoretical calculations were performed to elucidate the reasons behind the observed performance differences. These findings provide important theoretical insights for the design and application of amino-substituted nitro-pyrazole-based energetic materials.