Research Of Electronic Structure On Some Special Organic Fluorohydrogen Bond And Lithium Intercalation Mechanism Of Multicarbonyl Polyimide

Hydrogen bond plays a significant role in nature.Fluorine atom has a small volume,large electronegativity and low polarizability,the introduction of it in system often takes some excellent effects,because the introduction of fluorine atoms can change the electronic configuration of the molecule without adjusting it's conformation.Many drug researches have also reported the phenomenon that "the introduction of fluorine atoms can change the properties of compounds."Consequently,we studied some special fluorine hydrogen bonds and explored what influences geometric configuration and substituents have on the fluorine hydrogen bond.In addition,the aggravation of environmental pollution and the increasing consumption of energy are also constantly alarming human beings,searching for clean,efficient and large reserves energy sources has become one of the most urgent problems to be solved in contemporary society.Lithium ion batteries perform well in the field of clean energy,the key point of which is looking for suitable lithium ion battery materials.Traditional inorganic materials have great weaknesses in safety,battery capacity and sustainability.Therefore,researchers have focused on renewable,low-cost and environmental friendly new organic materials in recent years,a kind of material with multi-carbonyl amide structure and some properties when it is used as a battery electrode was reported in this article.This paper is mainly divided into the following four chapters:In chapter one,we introduced the basic knowledge of quantum chemistry,the theoretical methods used in this paper and the analytical methods derived from these theories,including perturbation theory,density functional theory(DFT),atom in molecules(AIM)theory,natural bond orbital(NBO)theory,molecular surface electrostatic potential analysis,energy decomposition analysis,spin-spin coupling analysis,etc.In chapter two,we added fluorine atom to the carbon atom which is directly connected to the carboxylic acid.The O-H…F-C hydrogen bond formed in our system.Based on the perturbation theory,three different types of carboxylic acid dimers were theoretically calculated to investigate the effect of fluoroalkyl on hydrogen bond in carboxylic acid dimer.We found that in R,CHFCOOH(R1=H,CH3,CH2CH3,CH2CH2CH3,CH(CH3)2,CH2CH2CH2CH3 and C(CH3)3)dimer,the most stable one is the structure containing a propyl,and when the number of carbon atoms in the substituent adds to 4,the interaction energy decreases.The NBO analysis shows that the intramolecular hyperconjugation results in the ortho cross conformation of the larger R group and the carboxyl group.More importantly,we found that the position of the fluorine atom can affect the position of the hydrogen bond and when fluorine atom is on ?-C of RCHFCOOH,the dimer perform the best in all complexes.In chapter three,we discussed a kind of cage compound based on Diels-Alder reaction.There are two kinds of mutual-balanced interaction:hybridization and hyperconjugation in the solid cage molecular.In order to study the influence of the skeleton structure,different substituents and the position of substituents on the hydrogen bond in rigid cage compounds,the AIM,NBO and NCI analysis under the perturbation theory were carried out.And the spin-spin coupling constant of the fluorine hydrogen bond were theoretically calculated based on the density functional theory.The hydrogen bonds in the cage system are mostly "uncommon" C-F…H-X blue shifted hydrogen bonds.NBO analysis shows that the X-H bonds are shortened due to the heavr hybridization,which is stronger than hyperconjugation.When the substituents are H,F,Cl,Br,OH and CN,in addition,electricity-absorbing group Cl,Br and CN will form strong hydrogen bond.To some extent,SSCC value computed in NMR study can indicate the strength of hydrogen bond.When the substituent group is on the donor X atom,the hydrogen bond strength is greater than that of the substituent group on the hydrogen bond acceptor,and when the hydrogen bond donor is oxygen cation or nitrogen cation,the stronger hydrogen bond is formed.In chapter four,we designed an aromatic polyimide compound BTAQ containing seven active C=O bonds as the electrode material of lithium-ion battery.The binding energy of complex BTAQ-Li was analyzed at B3LYP/6-31+G(d)level,and the LUMO orbital energy,Homo orbital energy and vertical ionization potential of bTaq monomer were calculated theoretically.According to the electron affinity of each BTAQ-Li complex,we found a suitable lithium intercalation step.We intercalated multiple Lis on the C=O and benzene ring C atom of BTAQ in turn and found that the bridging bond of Li-O-Li would be formed in the system and it was more stable than the general O-Li bond.In our system,all C=O bonds on BTAQ can stably bond to Li,but same effect is not seen in benzene ring C,that is to say,the bond of Li and benzene ring C was not ideal.The LUMO energy of BTAQ is small,which makes it an excellent electrode material in oxidation reaction.