Theoretical Investigation On Kinetics Of Aromatic Combustion Reactions And The Catalytic Mechanism Of Artificial Enzymes

In the advancement of science and technology,the large-scale experiments in various disciplines urgently require the combination of computational power of computers and knowledge of quantum theory to approximatively solve the theoretical values that could support the accuracy of the experiments,and it also can extract reliable principle information and illuminate the problem that experiments applied to actual production,which is imporment to reveal chemistry nature.This dissertation selects two popular systems(aromatics combustion and artificial enzyme catalysis)for basic and applied research.The theoretical research as follows:(1)The fundamental theoretical study of the kinetics of aromatic hydrocarbon combustion.We used SS-QRRK and tunneling effects to study(benzene and hydrogen radicals/o-xylene and hydroxyl radicals)two elementary reactions and accurately calculate the rate constants of the ion and addition reaction with temperature(220 K-3000 K)and pressure(500 atm-10 torr)and simulate the chemical environment that is in line with the experimental conditions for obtaining a wide range of reaction rate constants.In the benzene and hydrogen radical systems,the results show that negative temperature effect in the reaction is caused by the competitive relationship between the abstraction and addition reactions,and when the pressure fall down,the negative temperature effect occurs on the lower temperature.The effect of pressure on the rate constant in this area becomes more pronounced.In addition,under different carrier gas environments,such as H2,He2 and Ar2,the reaction rate has a difference of 1-2 times,which is related to the collision efficiency of the carrier gas in the unimolecule reaction.At the same time,isotope changes are extremely sensitive in ultra-low pressure(1-10 torr)environments.This is due to the fact that when the hydrogen atoms on benzene are deuterated,their reaction rate constants are significantly less sensitive to pressure changes than non-deuterated benzene molecules.In the systems of o-xylene and hydroxyl radicals,it is found that the tunneling effect caused by the complex will have a effect in the low-or no-energy barrier reaction.This study can promote the understanding of the aromatic compounds combustion processes and excavate effective methods from the mechanism level to improve combustion efficiency and reduce pollution emissions,in order to promote and even support the development of China's engine base combustion research.(2)The applied research of the catalytic mechanism of artificial enzymes.This project takes biotin-streptavidin affinity as an object,the cluster model of the reactive center was obtained by dynamtic simulation of S112H Sav and K121H Sav,aim to study the chemical environments that producing two chiral molecules in the system of imime reduction.The results indicate that there are four binding modes for imine to enter the protein.The different binding modes give rise to the different,the chirality of the product molecules is different,by analyzing and comparing the energy barrier of the rate-determining step,the dominant conformation of S112H Sav and K121H Sav is S and R,respectively.From a qualitative point of view,it is consistent with the experimental results.Considering the three-dimensional electronic effect and space effect of the environment in the reaction path,we found that when the methyl on Cp*replaced by imine,will decrease the energy barrier of the rate-determining step and get a more efficient artificial metal enzyme.That provides theory evidence and support for the development of biotin artificial metal enzymes.