Tuning The Excited States Of Au~Ⅲ And Pt~ⅡComplexes Showing Visible Light-harvesting And Long-life For Their Applications

In recent years, transition metal complexes as a kind of phosphorescent materials with excellent properties have been used widely, such as the application of solar cells, photodynamic therapy, oxygen sensing, photocatalysis, phosphorescent probe, as well as triplet-triplet annihilation (TTA) based upconversion. In this thesis, AuⅢ and PtⅡ complexes were mainly discussed. However, the conventional cyclometalated AuⅢ and PtⅡ complexes have weak absorption in the visible range and short lifetime of the T1excited state (usually less than5μs), which seriously limits their applications in many fields. Therefore, it is an important project to design the transition metal complexes with strong absorption of visible light, long-lived triplet excited state and high quantum yield. Herein, the photophysical properties of the novel PtⅡ and AuⅢ complexes were studied on the level of theory research by DFT/TDDFT methods. Then, we designed and synthesized series of N^N PtⅡ and C^N^C AuⅢ phosphorescent complexes. In addition, their photophysical and photochemical properties and their applications in the TTA up-conversion and as oxygen sensor of these were investigated in detail.We introduced Naphthoylimine(NI), BODIPY, Naphthalenediimide(NDI) to the Au metal center with alkynyl, and then design and synthesize C^N^C Au (Ⅲ) series of complexes. Through the introduction of the organic chromophores, the complexes show superior photophysical properties. The absorption within the visible range of Au-2, Au-3and Au-4were obviously enhanced, and the excited state lifetimes were increased to49.4μs,249.3μs,110.3μs respectively. It might mean that the phosphorescent emissions of Au-2, Au-3and Au-4are the emission of3IL*. The complex Au-2was measured in the application of oxygen sensor as photosensitizer. The results exhibit that Au-2shows very sensitive to oxygen and has higher determination sensitivity of trace oxygen contents. Au-3and Au-4were investigated in application of TTA upconversion as the triplet sensitizers. The upconvered efficiency7.02%and3.71%were obtained respectively.N^N PtⅡ complexes introduced modified coumarin ligand to the Pt metal center with the above way, and then designed and synthesized complexes Pt-3. The photophysical property of Pt-3was improving obviously compared with Pt-1and Pt-2. We confirmed its phosphorescent emissions are the emission of3IL*through the results of spectral testing data and DFT/TDDFT calculations. The complexes with favourable physical properties were used as triplet sensitizers for TTA upconversion, and the results show that Pt-3is an efficien sensitizer with an upconversion quantum yield of up to19.1%.In summary, our experimental results illustrate that the direct metalation of organic fluorophores should be an efficient method to make the transition metal complexes own the properties of strong absorption in the visible light and long-lived triplet excited states. Our work would also promote the study of applications of PtⅡ and AuⅢ complexes in TTA upcovnersion and oxygen sensor fileds.