Syntheses,Structures And Hole-Transport Properties Of C_2v-Type Heterocyclic Acridone Compounds

Organic semiconductor materials are an important branch in the field of organic photoelectric functional materials.For the development of organic semiconductor materials,it is of great significance to design and synthesize novel organic compounds with high efficient charge transfer performance and to explore their structure-property relations.This thesis mainly focus the attention on the study of the heterocyclic aromatic compounds with highly delocalized ?-electron system,highly rigid molecular skeleton,planar C_2v-or quasi-C_2v-symmetry and low charge transfer energy barrier.Two series of C_2v symmetric organic semiconductor compounds,namely indole-fused acridone and benzothiophene fused acridone,were synthesized by using C_2v symmetric acridone as the framework.In this paper,more than 30 new compounds were synthesized,and the crystal structures of most new compounds were determined,their photophysical properties were studied,some single-crystal devices were fabricated and the semiconductor properties were measured.The main research contents and conclusions are as follows(the structural formula of the target compounds described below is listed in the table 1-2 in the introduction):1.N-methyl indole-fused acridone:syntheses,structures,intramolecular proton transfer and intermolecular hole transport properties.Three pairs of regioisomeric indole-fused acridone compounds(1-IAD vs 3-IAD,Br-1-IAD vs Br-3-IAD,1,1'-IAD vs 1,3'-IAD)were synthesized for the first time by Suzuki coupling and Cadogan cyclization reactions.Relative to the 3-cyclized compounds(3-IAD,Br-3-IAD and 1,3'-IAD),the 1-cyclized isomers(1-IAD,Br-l-LAD and 1,1'-IAD)have higher yields and lower energies.X-ray determinations show that the three pairs of isomers have good molecular planarity.There are two emission bands in the fluorescence spectra of intramolecular H-bond containing compounds(1-IAD,Br-1-IAD,1,1'-IAD and 1,3'-IAD),showing the characteristics of excited state intramolecular proton transfer(ESIPT).According to the DFT calculations,the reorganization energy(?)of 1,1'-IAD and 1,3'-IAD are approximately 0.1 eV.The preliminary mobility measurements of the field-effect transistor devices based on the two compounds are 1.5×10^-2cm²V^-1s^-1 and 3.9×10^-5cm²V^-1s^-1,respectively.This indicates that the indole-fused acridone compounds have good hole transport properties and switching properties.2.Benzothiophene-fused acridone:syntheses,structures and hole transport properties.Six N-methylated and N-ethylated benzothiophene-fused acridone compounds(BT-AD-1/2,BTS-AD-1/2,BTSO-AD-1 and BBT-AD-2)were synthesized for the first time by Suzuki coupling,triflic acid induced ring-closure reaction and iodine-promoted cyclization,and the single crystal structures of four compounds were determined.The energy level structures,luminescence properties and theoretical hole transport properties of N-ethylated target molecules are studied.Both the absorption and emission peaks are red-shifted with the increasing of the ?-conjugation.The DFT calculation results show that,compared with indole-fused acridone compounds,benzothiophene-fused acridone compounds have lower hole transfer barrier,stronger intermolecular interactions and better hole transport performance.3.N-ethyl halogenated acridone and double indole-fused acridone:syntheses,structures and hole transport properties.Three 2,7-positions halogenated acridone(Cl-Et-AD,Br-Et-AD and I-Et-AD)were synthesized for the first time by different routes.Et-IAD was synthesized by Suzuki coupling reaction and Cadogan cyclization.The single crystal structures of all the target compounds were determined.Different crystalline solvents can be used to regulate the molecular packing in Et-IAD crystals.The introduction of different halogen atoms resulted in significant differences in the molecular stacking and solid-state fluorescence spectra of the halogenated acridone.The DFT calculation show that the introduction of electron withdrawing halogen reduces the LUMO energy level and may lead to the development to n-type materials4.Two pyrene-based S-containing atropisomers:structures and Ag⁺ responseThe single crystal structures and photophysical properties of two pyrene-based S-containing atropisomers(s-BSPPy and a-BSPP)were systematically investigated.The fluorescence response behaviors of two atropisomers to metal ions were also explored.The results show that the syn-isomer s-BSPPy has edge-to-face ?-shaped excimer luminescence.After adding Ag⁺,excimer emission quenched and monomer luminescence increased,indicating that s-BSPPy can be used as a sensitive fluorescent probe for Ag⁺.In summary,we have designed and synthesized a class of ?-extended organic semiconductor molecules based on acridone skeleton.Their crystal structures and luminescence behaviors in solution and solid state have been recovered.Based on the crystals of target compounds,the hole transport properties have been studied by DFT calculation and organic field-effect transistor device test.In this thesis,a new kind of photoelectric material based on acridone and its application in OFETs have been explored,and many significant experimental results have been obtained.