Study Of Theoretical Chemistry Of Anthraquinone And Its Derivatives

Anthraquinone and its derivatives, which are not only an important kind of dye but also the composition of many drugs, have been widely used in various fields. In this dissertation, a relatively high level theoretical investigation has been performed using the density functional theory (DFT) and time-dependent density functional theory (TD-DFT) methods to study the structures and properties of a series of anthraquinones. The relationship between the structures and properties was discussed in detail. Molecular dynamics (MD) simulation has been performed too to simulate the adsorption of the dye molecules, such as disperse red and disperse blue on nylons-6Compared with the experimental and MP2/6-31G* results, B3LYP/6-31G* yields satisfactory results and can be considered as an optimal method, and is therefore used to calculate anthraquinone and its derivatives. The calculation indicates that all the title compounds have planar structures and exhibit strong intramolecular hydrogen bond, which has a visible influence on the configuration and properties of molecules. Normal-mode analyses were used to characterize the stable point (energy minimum) and to determine the harmonic vibrational frequencies, and quite good results were achieved compared with the experimental results. The standard thermodynamic properties of anthraquinones were subsequently calculated based on the statistical thermodynamic principle. The ultraviolet spectra have been calculated using TD-DFT approach. The calculated results show that the first singlet excited states of the title compounds are resulted from the electron transition from the highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO) . The intramolecular proton transition mechanism was studied and the activation energy was also calculated using the QST2 method and 6-31G* basis set.The influence of various substitution groups at different positions on the geometrical structures, electronic structures, and the electronic spectra have been investigated, and the calculated results agree well with the experimental data. The substitution groups mainly affect the geometrical parameters and charge distributions near the substitution position, and the electron-accepting groups decrease while the electron-donating groups increase the energies of the frontier molecular orbitals.The B3LYP/LANL2DZ method has been applied to study the molecular structures, infrared spectra, and ultraviolet spectra of Ni(II), Fe(II) and Zn(II) complexes of...