New green energetic materials based on unsymmetrically substituted pyrazole-tetrazines and their hydroperchlorates

Five novel nitrogen-rich energetic materials were synthesized using 3,6-bis(3,5-dimethyl-pyrazole-1-yl)-1,2,4,5-tetrazine (BT) and 3,6-bis(pyrazole-1-yl)-1,2,4,5-tetrazine as raw materials. The materials were comprehensively characterized by single-crystal X-ray diffraction, FT-IR, mass spectra and elemental analysis. The synthesized compounds show good experimental densities, ranging from 1.59 to 1.70 g cm^-3. DSC technology was used for analyzing the thermal stability. The decomposition temperatures of the five energetic materials ranged from 204.0 to 276.5 °C. Non-isothermal kinetic parameters and formation enthalpy values were computed. In addition, friction sensitivity measurements were performed according to BAM methods, and the results showed that the five compounds can be classified as insensitive energetic materials. For a better understanding of the electronic structural characteristics, the electrostatic potential (ESP) and natural bond orbitals (NBOs) of compounds 1 and 2 were further computed. The detonation parameters were obtained via EXPLO5 V6.04. The detonation velocities of the five energetic materials were found to be in the range of 6436 m s^-1 to 7759 m s^-1, and their detonation pressures are between 15.8 GPa and 24.6 GPa. Most of them exhibit much better detonation performance than TNT.