Synthesis, structure and properties of a high-energy metal–organic framework fuel [Cu(MTZ)2(CTB)2]n

Abstract

In this study, a novel high-energy metal–organic framework (MOF, [Cu(MTZ)₂(CTB)₂]_n) was constructed based on the nitrogen-rich cyanotetrazolylborohydride (CTB) and 1-methyltriazole (MTZ) ligands, with Cu²⁺ as the autocatalytic metal centers. The synthesized MOF is characterized as a fascinating 1D framework architecture, due to the bridged CTB linkers. The sensitivities of the MOF are excellent (IS > 40 J, FS > 360 N), and the energy densities (E_g = 22.63 kJ g⁻¹, E_v = 35.30 kJ cm⁻³) are somewhat higher than those of some hydrazine fuels. [Cu(MTZ)₂(CTB)₂]_n can be hypergolically ignited when contacted with white fuming nitric acid (WFNA) with a delay time of 30 ms, and a maximum specific impulse of 247 s. Moreover, this MOF was also suggested as the fuel of composite energetic materials, because of its high energy and low sensitivity. The mixture of [Cu(MTZ)₂(CTB)₂]_n and ammonium perchlorate (AP) exhibits an excellent energetic performance, a detonation pressure of 30.9 GPa, a detonation velocity of 8120.3 m s⁻¹, and a specific impulse of 261.3 s calculated by EXPLO5. In short, the high-energy [Cu(MTZ)₂(CTB)₂]_n synthesized in this work has wide potential applications in the field of energetic materials.