Interaction Characteristics Of Small Molecules Of Biological Model And The Electron Transfer Reaction

The chemical questions in the biology became important to the people. The theory and the method of the chemistry have been applied to the study of biology and iatrology. We have studied the structural character of the model small molecules related to the biological processes and the interaction strength between them, such as NO, NO+, NO", SO and some ions. In this paper, we mainly focus on the following two parts: interaction part and electron-transfer part.1. Interaction1.1. The NO dimmer cation, (NO)2+. has been studied by using density function theory. The geometries and the harmonic vibrational frequency of (NO)2+ have been calculated at B3LYP/6-311++G** level. The results indicate that there are five stable doublet states. The ground state is determined to be the trans isomer with N-N bond linkage, which has C2h symmetry. The relative stability of all stable geometric structures has been analyzed. The state-state correlation and the isomerization mechanism are predicted by searching the transition states.1.2. Using different theory, especially the density function theory, we calculated the geometris of the (NO)2- and harmonic vibrational frequency. The results indicate that there are seven stable doublet states. The analysis of the dissociation energy indicates that five structures were linked by the strong interaction, other two structures were linked by chemical bond.1.3. The geometries and the harmonic vibrational frequencies for several SNO doublet state isomers have been predicted at density functional theory levels with a 6-311+G* basis set. Results have indicated that there are nine doublet states (five bent, three nearly linear and one cyclic). The ground state corresponds to a bent 2A' SNO structure. The state-statecorrelation and the isomerization mechanism are also predicted by searching the transition states and the intrinsic reaction coordinate analysis. Results have indicated that the ground state is the most favorable products. 1.4. The geometries and the harmonic vibrational frequencies for SiSO+ and GeSO+ have been predicted at density functional theory levels with a 6-311-t-G* basis set. Results have indicated that there are four doublet states, respectively. The nearly linear Si-O-S+ structure is referred to as the ground state, as to the GeSO+, the ground state is the cyclic 2A" state. The dissociation energy of the linear M-OS+ state has been calculated. The bonding character of the structures has been ayslyzed.2. Electron transfer2.1. Some basis mechanics, especially the activation model and the theoretical expression of the electron-transfer rate used in this paper have also been introduced. The theory is based on the same sticking point, which are the difference of the equilibrium structure when a molecule or a cation receive or lose a electron and the electronic factor of electron transfer.2.2. At the basis of the calculated geometry, using the theory introduced above, we calculated the electron-transfer rate of the NO/NO+ system at different mechanics. The inverse symmetry broken at the calculation of the dissociation energy using density function theory has been discussed. Inverse symmetry breaking was a common phenomenon for the DFT results for the radical ion with two equivalent fragments. Inverse symmetry breaking may be the inherent character of the non-HF DFT exchange functionals.