New Aggregation-Induced Emission Compounds And The Investigation Of Their Mechanism, Property, And Application

Nowadays,in the field of aggregation-induced emission?AIE?,the investigation and exploration of AIE mechanism,as well as the development of new structure,new property,and new application of AIE compounds,are the main research goals.In this thesis,we designed and synthesized a series of new AIE core structures and their derivatives,studied their emission mechanism,and explored their applications in oncotherapy and organic laser.In terms of structure and property,we designed and obtained ten 9,10-ethenoanthracene derivatives through simple and efficient synthetic routes.In their crystalline state,dual emission of fluorescence at short wavelength and room temperature phosphorescence at long wavelength can be observed for all the ten compounds with the longest emission lifetime of up to 7.38 ms.Among them,some compounds even show triple emission of simultaneous fluorescence,room temperature phosphorescence,and delayed fluorescence.Theoretical calculation suggests that the energy gap between S₁ and T₁ state are generally larger than 0.45eV,and the delayed fluorescence should be attributed to triplet-triplet annihilation.The in-depth study of the emission behavior of these 9,10-ethenoanthracene derivatives may provide design principle for new luminescent materials utilizing triple state emission.In terms of mechanism investigation,we found a series of azabenzanthrone derivatives with rigid and coplanar structure,which do not possess any intermolecular rotatable or vibratile moieties,but show AIE property.Through the combination of systematical characterization of photophysical properties of these coplanar AIE compounds and theoretical calculation,it is demonstrated that their AIE property is because their transition type has changed from the forbidden n-?*transition in solution state to the allowed?-?*transition in the aggregated state.This study has expanded the mechanism of AIE phenomenon.In terms of application exploration,we further utilized the azabenzanthrone core structure as electron acceptor,modified with different electron donors based on this core structure,and obtained a series of red emissive AIE compounds.They generally enjoy long emission wavelength,efficient photo-induced reactive oxygen species generation,and good photo-stability.These dyes were utilized in photodynamic therapy as photosensitizers,which can kill Hela cells efficiently with ultralow light irradiation intensity?1.67 mW/cm²?.Moreover,these dyes are fabricated into nanoparticles and realized two-photon imaging of mouse brain vessels at 280?m depth.This work demonstrated the potential application of the red-emissive AIE compounds in photodynamic therapy and bio-imaging.Base on the azabenzanthrone core structure,alkyl chains were also introduced to increase their solubility in organic media,which could be doped into epoxy resin with high concentration and serve as efficient organic laser dyes.The optical fiber laser based on these dyes were fabricated and the light pumped laser emission threshold was as low as 0.1MW/cm².Taking advantages of their AIE property,these dyes can be doped into epoxy resin with high concentration,avoid the concentration-caused fluorescence quenching effect of traditional organic dyes.Through the optimization of the test condition,single longitudinal mode laser was gained with the half band width of 0.25 nm.