The Preparation And Study Of Large Conjugated Aromatic Triplet Photosensitizers

The most remarkable characteristic of triplet photosensitizers is its long excited state lifetime??s,ms,and even s scale?,and thus it has important potential application for electron transfer,energy transfer and chemical reaction.At present,the application of triplet molecules is mainly focused on photodynamic therapy,photoredox,oxygen sensing and up-conversion,but research in the field of new applications is very rare.It is very important to develop new application for triplet photosensitizers.In addition,the molecular structure and performance requirements of triplet photosensitizers are different in different application fields,however,the common molecular design idea is to prepare triplet photosensitizers with the characteristics of simple synthesis,low cost,predictable intersystem crossing process,high triplet efficiency and long triplet lifetime.The application of triplet photosensitizers in molecular logic gates is studied,a photoinduced electron transfer molecule Py-M has been synthesized.Py-M is able to respond to reduced glutathione?GSH?containing the thiol group.When the concentration of GSH in system is in the range of 0?40 mM,the fluorescence intensity of Py-M increased with the increase of GSH concentration.However,oxidative glutathione?GSSG?can't enhance fluorescence of Py-M,make use of this difference,and the redox reaction between GSH and GSSG?H₂O₂ can oxidize GSH to GSSG,and glutathione reductase?GR?can reduce GSSG to GSH?,the regulation of Py-M fluorescence was preliminarily realized.Triplet-triplet annihilation up-conversion system was constructed with diiodoBodipy as photosensitizer molecule and Py-M as energy receptor,the up-conversion luminescence was successfully regulated by the method of regulating the fluorescence,and established three input logic gates,AND,INHIBIT and enable OR,four input combinational logic gates are constructed by series and parallel connection.In order to design new triplet photosensitizer,the effects of molecular orientation and electron coupling intensity on the process of spin orbital charge transfer intersystem crossing?SOCT-ISC?were also investigated.SOCT-ISC is a novel type of mechanism to generate triplet state which is based on the electron transfer process.Electron donor/acceptor dyad systems consisting of perylenemonoimide and carbazole were synthesized in this thesis,and steady state spectra were used to study the absorption,luminescence and singlet oxygen quantum yield under different solvent polarity.The difference between SOCT-ISC and traditional spin orbit coupling intersystem crossing?SOC-ISC?was compared,and the process of electron transfer was proved,the effects of electron-coupling strength and solvent polarity on the energy level of charge separation state were also investigated by electrochemical studies,the molecular geometry and excited state energy levels were calculated by the DFT calculation.The results demonstrated that the ground state configuration of the molecule?mainly the dihedral Angle between the donor/acceptor?has an important effect on the intersystem crossing efficiency.When the molecular structure is closer to the perpendicular configuration,the intersystem crossing efficiency will be higher.