Theoretical investigation of the structure, detonation properties, and stability of bicyclo[3.2.1]octane derivatives.

A series of nitro group and aza nitrogen atom derivatives, based on bicyclo[3.2.1]octane, were designed and studied by theoretical methods. The geometric structure calculations were performed at B3LYP/6-311G(d,p), B3P86/6-311G(d,p), B3LYP/6-31G(d), and B3PW91/6-31G(d,p) levels. The electrostatic potential analysis, heats of formation, densities, heats of sublimation, detonation performances, bond dissociation energies (BDEs), and impact sensitivities of the designed compounds were calculated by reasonable calculation methods to evaluate their comprehensive properties and establish the relationship between structure and performance. Results show that density and detonation properties always increase with the increasing number of nitro groups and aza nitrogen atoms. BDEs generally decrease with the increasing number of nitro groups. Except for BDEs of A9, B9, and D8, BDEs of all designed compounds are larger than 20 kcal mol and meet the requirement for new high energy density compounds (HEDCs). Two theoretical prediction methods show all the designed compounds have an acceptable impact sensitivity. Detonation velocity and detonation pressure were predicted in the range of 5.24-9.59 km/s and 9.97-43.44 GPa, respectively. Eleven compounds have better detonation properties than HMX, and seven compounds meet the criteria for HEDCs. Taking thermal stability and impact sensitivity into consideration, four compounds (C9, E8, F8, and G7) may be considered as new potential HEDCs, and C9, E8, and F8 may have similar detonation properties to the famous CL-20. Graphical abstractFour new HEDCs with acceptable impact sensitivity (C9, E8 and F8 may have similar detonation properties to the famous CL-20).