Design,Synthesis And Properties Of Tunable Organic Fluorescence And Room Temperature Phosphorescent Materials

Organic luminescent materials have been widely used in electronic luminescence,information storage,fluorescent probe,biological science and other fields for their excellent photophysical properties.However,single luminescent materials have been difficult to meet the needs of practical applications,and the tunability of luminescent materials is worthy of be further studied.Therefore,it is important to design and synthesize materials with tunable luminescence properties.The emission properties of organic photoluminescent molecules depend largely on the electron transitions between different excited states.In this paper,the molecular excited state of the material is regulated by adjusting the molecular energy level and molecular stacking structure,and the luminescence performance of the material is regulated.Organic fluorescence and room temperature phosphorescent materials with tunable luminescence properties are reported,and the research on the relationship of structure and properties at the molecular level provided a feasible strategy for the regulation of luminescent properties of materials.In chapter 2,an aggregate-induced luminescent polymorph material with multi-stimulus tunable luminescence is synthesized by modifying carbazole at both ends of fluorenone.Two kinds of crystals with different fluorescence properties were obtained by adjusting the solvent ratio culture,and the switch between the two crystals was realized under the induction of solvent.It's found that the polymorph dependent fluorescence performance is closely related to the molecular stacking,and the crystal-to-crystal switch is caused by the capture/release of dichloromethane,which alters the molecular stacking.In addition,the fluorescence properties of the materials are further regulated by mechanical force,heat and other stimuli.In chapter 3,based on 9-phenyl-9-hydrogen-carbazole,a series of efficient organic room temperature phosphorescence(RTP)materials are designed and synthesized by introducing cyanide and halogen atoms,namely,CzBz,CzBzF,CzBzCl and CzBzBr,and the RTP properties were successfully adjusted.Among them,CzBzCl shows efficient and persistent RTP emission,while CzBzBr shows ultra-high phosphorescent quantum yield,which is due to the heavy atom effect brought by halogen atoms and the synergistic effect of halogen bonds.The heavy atom effect can greatly enhance the intermolecular crosshafts,and the halogen bonding interaction leads to the special halogen clusters packing mode,which greatly stabilizes the triplet excitons.In addition,the co-crystal strategy is further used to adjust the heavy atom effect,and the luminescence properties and RTP characteristics of the materials are regulated.