A Theoretical Study On Organic Fluoreniod #-Shaped Gridspiroarenes

Porphyrin,a square planar 18π aromatic macroring,is composed of four pyrroles and four methylene carbons.It can be said that it is the most important pigment that found in nature.Because it has many excellent characteristics,such as strong structure,attractive absorption and emission characteristics,strong aromaticity and metal coordination chemistry,porphyrin has been used in many research disciplines.Porphyrins also play an important role in the field of organic electronics and photonics because of their large planarπconjugated electron rich structure,many modifiable active sites and good physical and chemical stability.Porphyrins have the ability to coordinate with up to 56 different metals in the central cavity.The purpose of building materials with diversified functional requirements can be achieved by changing the category of central metals.Considering the non-covalent supramolecular effect of porphyrins,it is widely used in the research of ionic molecular self-assembly,COF/MOF construction,catalysis,ion detection and other fields.In addition,due to these unusual characteristics of porphyrins,people pay more and more attention to the fact that porphyrin electronic systems are vulnerable to conjugated peripheral disturbances,so they begin to allow reasonable electronic fine-tuning to achieve the purpose that the system can have different optical and electronic characteristics.Porphyrins have many future applications,such as NIR dyes,photovoltaic dyes,nonlinear optical materials and nano electronic devices.Based on these,three kinds of porphyrin stacked lattice aromatic molecules are designed,and the theoretical calculation and prediction research is carried out by using the method of quantum chemical calculation,including the ground state structure of the molecule,the weak interaction in the molecule,the frontier molecular orbital,ionization energy,electron affinity,vibration mode,absorption spectrum and reorganization energy.In particular,the effects of stacking distance and connection mode on the reorganization energy are studied.The main research contents are as follows:1.By changing the connecting bond between two porphyrin planes and changing the stacking structure,a series of small-distance stacking porphyrin molecules are designed,and metal atoms are inserted into the porphyrin Center for comparison.The ground state structure,weak interaction,frontier molecular orbital,ionization energy,electron affinity,vibration mode,reorganization energy and spectrum of these molecules are calculated by quantum chemistry.To investigate the effect of stacking distance on molecular photophysical properties.It is concluded that Eg decreases with increasing distance.The two porphyrin planar molecules connected by single bond are lower than those connected by double bond;With the increase of stacking distance,the reorganization energy decreases and the types of weak interaction decrease;When Ni central atom is inserted,Eg increases and the substance is more stable.2.Based on the first chapter,a series of large-distance stacked porphyrin molecules were designed.The carbon chain between two stacked porphyrin planes is changed into benzene ring,and the stacking distance is changed by increasing the number of benzene rings.The ground state structure,weak interaction force,frontier molecular orbital,IPa,EAa,vibration mode,reorganization energy and absorption spectrum of this series of molecules are theoretically calculated to investigate the effects of stacking distance and connection mode on molecular photophysical properties.Large distance stacked porphyrin lattice aromatic molecules have the following lattice effects:with the increase of distance,the reorganization energy decreases and E_gdecreases,the reorganization energy is lower than 0.1e V.It is a good hole and electron transport material,and the reorganization energy of porphyrin molecules connected by three benzene rings is the lowest,that is,when the distance between two porphyrin planes is 5.035?.3.Rearrange theπorbitals with fluorene structure to obtain the trapezoidal stacked molecules with degenerate frontier molecular orbitals,design the porphyrin molecules containing thiophene based reaction active sites,and use thiophene as the centralπbridge to form a complete bridging structure,which can produce energy transfer.The different configurations of the molecule were found,and the ground state structure,weak interaction,molecular orbital,IPa,EAa and UV-VL spectrum of these configurations were calculated by quantum chemistry to compare the differences of photophysical properties of porphyrin,thiophene and fluorene based molecules with different configurations.On this basis,the fluorene group was removed,the lattice molecules of porphyrin and thiophene were constructed,and different configurations were found to form a contrast with the former.These results show that by changing the stacking distance of porphyrins and the connection mode between stacking planes,porphyrin stacking molecules with low reorganization energy can be obtained,It is advantageous to synthesize organic semiconductors with high mobility experimentally and lays a foundation for obtaining luminescent materials with high mobility.