From mono-rings to bridged bi-rings to caged bi-rings: a promising design strategy for all-nitrogen high-energy-density materialsN₁₀andN₁₂

The research of all-nitrogen compounds has always been a hot topic in nitrogen chemistry and high-energy-density material communities. This research mainly focuses on acyclic and monocyclic all-nitrogen derivatives, while the bicyclic systems of all-nitrogen materials have been rarely investigated. In this study, four bicyclic all-nitrogen derivatives,vizbridgedN₁₀andN₁₂, and cagedN₁₀andN₁₂, are presented. Caged-N₁₀and caged-N₁₂exhibit much higher density (d: 1.84 and 1.89 g cm⁻³) and higher heats of formation (H_f: 15.19 and 16.41 kJ g⁻¹) than bridged-N₁₀and bridged-N₁₂(d: 1.71 and 1.72 g cm⁻³;H_f: 7.64 and 10.24 kJ g⁻¹), respectively. All these materials exhibit remarkable detonation performance (D: 9.87-12.29 km s⁻¹;P: 39.41-72.26 GPa) and excellent specific impulses (I_sp: 325.00-434.60 s), which is superior to the state-of-artCL-20(D: 9.40 km s⁻¹;P: 44.60 GPa;I_sp: 272.61 s), endowing these materials with great potential as promising explosives and propellants. In addition, molecular electrostatic potentials, frontier molecular orbitals, and noncovalent interactions were studied to investigate their structure-property relationship.