Molecular Design Of Pentazole Salts And Theoretical Studies On The Effects Of Solvents And Pressure

Pentazole compound is a kind of high energy density materials with potential applications and is currently a hot research topic too.It is necessary and meaningful to perform more systematic and in-depth studies on these materials.In this thesis,the geometric structure,electronic structure,stability,detonation performance,crystal structure and other properties of pentazole compounds were studied using the density functional theory(DFT)methods.The main contents are as follows:1.The effects of nine different solvents such as methanol etc.on the structure and properties of Zn(N₅)₂ were studied using the polarized continuum model.The results of geometric structures,electronic structures and solvation energies show that solvents make Zn(N₅)₂ more stable and the effect of water is more significant.To understand the stabilization mechanism of water,further studies were performed using the explicit solvent model.Results show it is the strong hydrogen bonding interactions and solvent-metal interactions raised by water that improves the stability of Zn(N₅)₂.2.The structures and properties of pentazole compounds[M(H₂O)₄(N₅)₂]·4H₂O and[M(NH₃)₄(N₅)₂]·4NH₃(M=Mn,Fe,Co,Zn)were studied.H₂O and NH₃ as ligands can reduce the interaction between metal and N₅^-,inhibit the decomposition of N₅^-,and form complex hydrogen bond network,which can improve the stability of the compounds.But the hydrogen bond and stability effect raised by NH₃ is weaker than that by H₂O.3.The influences of pressure on the structures and properties of[M(H₂O)₄(N₅)₂]·4H₂O(M=Mn,Fe,Co,Zn)were studied by using the periodic DFT methods.Results indicate that LDA/CA-PZ is a more reliable method than GGA/PW91 for these compounds.As the pressure increases,the band gap decreases and the optical absorption activity increases.4.Three kinds of cations were designed by introducing the nitro group into the N-heterocyclic cations(including monocyclic and polycyclic cations)to increase the nitrogen content and oxygen balance and to achieve better explosive performances.The densities,stabilities,and energetic performances of thirty energetic salts formed by these cations and N₅^-anion were evaluated.The effects of structure on these properties were analyzed.Some candidates with good performance were found.