Theoretical studies of pentazole-based compounds with high detonation performance

Four types of pentazole ring-based organic compounds, including triaminotripentazolobenzene (TATPB), triaminotripentazolocyclohexane (TATPH), trinitrotripentazolobenzene (TNTPB) and trinitrotripentazolocyclohexane (TNTPH) were designed and investigated by ab initio quantum chemistry methods. The geometric structure in the gas phase, electrostatic potential, HOMO-LUMO orbitals, and Wiberg bond orders was calculated at the level of B3LYP/6-311g. Several properties were predicted based on the calculation results above. Among the four compounds, TNTPB has the highest predicted packing density (1.85 g cm⁻³), the highest theoretical enthalpy of formation in solid phase (1486.89 kJ mol⁻¹) and the most powerful theoretical detonation performance (D = 9.36 km s⁻¹ and P = 38.05 GPa). The detonation properties of TNTPB are comparable to the new generation of explosives. Two possible solid phases of TNTPB in P$1ˉ$ and P2₁/c space groups were predicted. The periodic structures were optimized by periodic first-principles calculations with van der Waals correction. Ab initio molecular dynamics simulations were performed to confirm that TNTPB had the higher detonation growth rate than TATB (2,4,6-trinitro-1,3,5-benzenetriamine). We proposed that introducing the pentazole rings into designing high energy density materials (HEDMs) is an effective method for not only improving the detonation performance but also accelerating the detonation growth.