| We studied theoretically several kinds of caged energetic materials using the density functional theory (DFT) implemented in the Gaussian 98 program package. Based on the previous studies, the molecular design was performed for studied molecules so as to discuss the effect of the change of molecular electronic structure on the explosive performance. In our work, the studied aspects are as follows: i) molecular geometry and electronic structure; ii) the analysis of the electronic structure using Natural Bond Orbital (NBO) and Atoms in Molecules (AIM); iii) some physico-chemical properties of studied compounds: dipole moment, IR vibrational spectrum, NMR chemical shift, heat of formation, and relative specific impulse, were provided. First, the caged molecule HNIW was studied. The optimization was carried out and the vibrational frequencies were calculated at the theoretical level of B3LYP/6-31G**. The electronic structure was analyzed using NBO and AIM. Compared with experimental data, the properties of HNIW were studied as a kind of energetic material. Furthermore, at the same level, the four conformers were obtained by changing the spatial orientation of -NO2. The same analyses were performed for the four conformers so as to discuss the effect of the conformation on the electronic structure and molecular total energy.Second, the molecule design was carried out for three kinds of caged molecules, (CH)4, (CH)6, and (CH)8: i) substitute N atom for CH group so at to increase the content of N as well as reduce the content of H; ii) substitute -NO2 for H atom so as to increase the content of N and O atom and reduce the content of H. Consequently, a series compounds were obtained: (CH)xNn-x and Cn(NO2)n-xHx (n = 4, 6 or 8, x ≤ n). Using the quantum chemistry method, their geometries, electronic structures, heats of formation, vibrational frequencies, NMR chemical shift and relative specific impulses were studied in details. Our studies showed that these compounds may be a kind of potential and novel energetic material and our work provide some useful information for further studying them experimentally. As an important high energy density material, it is significant to study the electronic structures of polynitrocubane, which were studied in a special aspect, the intramolecular hydrogen bonding, in a section of this thesis. The optimizations, the vibrational frequency calculation, the analyses of NBO and AIM were performed at the theoretical level of B3LYP/6-31G** for the fifteen nitro derivatives of cubane. The results showed that all of the intramolecular hydrogen bonds in nitro derivatives are blue-shifting. The charge transfer processes, which created the blue-shifting hydrogen bonds, can be classified into two types. The effect of each process on the molecular structure and the stability was discussed.In the last section, di(2-sulfhydryl-1,3,5-triazine)-ethynylene and its nitro-, amino-, and hydroxyl-substituted derivatives were studied as the molecular devices. The interactions between the spatial effect and electron effect caused by substituent of nitro-, amino-, and hydroxyl groups of these compounds in different solvents were discussed. The purpose of studying this series compounds is to understand the effect of substituent of nitro-, amino-, and hydroxyl groups on the Cδ atom on the geometries, charge distribution, relative energies, and conductivity of the designed molecule devices. On the other hand, on the basis of calculation, the possibility of di(2-sulfhydryl-1,3,5-triazine)-ethynylene and its nitro-, amino-, and hydroxyl-substituted derivatives as a kinds molecular device was discussed.
|
PDF Full Text Request