Molecular Designs Of New Energetic Nitrogen-containing Heterocycle Compounds

Recently, energetic nitrogen-containing heterocycle compounds have become a type of new energetic materials with a good prospect of application. In this thesis, density function theory (DFT) method was used to study four types of energetic nitrogen-containing heterocycle compounds, and by comparing their detonation performance and thermal stability with those of traditional explosives RDX and HMX, the potential candidates of high-energy density compounds were selected. These results provide basic information for the design and synthesis of novel high-energy density compounds. Main parts of the study are as follows:The first part:The DFT-B3LYP/6-31G**method was used to study the heats of formation (HOFs), electronic structure, detonation properties, and thermal stability of a series of4,8-dihydrodifurazano[3,4-6,e]pyrazine derivatives. The isodesmic reaction method was employed to calculate the HOFs of the derivatives using total energies obtained from DFT calculations. On basis of the theoretical densities and HOFs, the semiempirical Kamlet-Jacobs equations were used to estimate their detonation velocities and pressures. The bond dissociation energies and bond orders for the weakest bonds were analyzed to investigate their thermal stability. According to their detonation performance and thermal stability, two compounds may be considered as the potential candidates of high-energy density compounds.The second part:The HOFs, densitied, detonation properties and thermal stability of a series of four-membered, six-memebered, and eight-memebered nitrogen-containing ring derivatives containing difluoramino groups. First, the total energies method was used to obtain their HOFs by designing isoseismic reaction. Second, based on the theoretical densities and HOFs, the detonation velocities and pressures were estimated by using the Kamlet-Jacobs equations. Finally, by analyzing the bond orders and bond dissociation energies for the weakest bonds, which may be the trigger bond during thermal decomposition, their thermal stability was determined.The third part:The geometric stuctures of a series of1,3-dinitroazetidine derivatives were optimized at the B3LYP/6-31G**level to calculate their total energies and HOMO and LUMO energies. Then, their HOFs values were calculated through isoseismic reaction and the effects of different substituents and heterocycle on the HOFs were discussed. The Kamlet-Jacobs equations were employed to calculate their detonation velocities and pressures by using theoretical densities. The bond orders and bond dissociation energies of the weakest bonds were compared to predict their thermal stability and the the potential candidates with good performance and stability were selected. The forth part:The effects of different substituents on the HOFs, electronic structure, detonation properties, and thermal stability of3,6-2H-1,2,4,5-tetrazine and its derivatives were investigated. Their HOFs were calculated by designing isoseismic reactiona and using total energies. Based on the theoretical densities and HOFs, the Kamlet-Jacobs equations were used to estimate their detonation velocities and pressures. The effects of different substituents and substitution positions on the detonation properties were discussed. Their thermal stability was estimated by comparison of bond dissociation energies of several relatively weak bonds.These results provide basic information for the molecular design of novel high-energy density compounds.