A novel multi-nitrogen 2,4,6,8,10,12-hexanitrohexaazaisowurtzitane based energetic cocrystal with 1-methyl-3,4,5-trinitropyrazole as a donor: experimental and theoretical investigations of intermolecular interactions
A novel multi-nitrogen energetic cocrystal 2,4,6,8,10,12-hexanitrohexaazaisowurtzitane (CL-20) and 1-methyl-3,4,5-trinitropyrazole (MTNP) in a 1:1 molar ratio was prepared and confirmed by X-ray diffraction. Instead of traditional aromatic donors such as 2,4,6-trinitrotoluene (TNT) and 2,4,6-trinitrobenzene (TNB), multi-nitrogen azole compound was introduced in this work. CL-20:MTNP has a high crystal density of 1.932 g cm-3 at 293(2)K, and superior detonation performance (νD=9347 m s-1, P=40.5 GPa) due to its high heat of formation, nitrogen-content and oxygen-balance. Meanwhile, measured impact and friction sensitivities (IS=6J, FS=180N) show that it is more insensitive than those of CL-20, close to those of RDX and HMX. To analyze the intermolecular interaction of CL-20:MTNP, a series of theoretical measures were employed including Hirshfeld surfaces, non-covalent interaction plots, interaction energies calculations and electrostatic surface potential distributions. The physicochemical performance implies that CL-20:MTNP is expected to be a promising energetic material and the methyl substituted low-point explosives acting as donor-acceptor can be a new strategy for constructing series of novel multi-nitrogen energetic cocrystals towards the future high-performance-energetic-materials.