| IrⅢ complexes have attracted much attention owing to their applicabilities in electroluminescence, oxygen sensing, triplet-triplet annihilation (TTA) upconversion and photocatalysis. However, traditional IrⅢ complexes show weak absorption of visible light and short triplet excited state lifetimes that affects the newly developed applications (photocatalysis, photodynamic therapy and TTA upconversion) seriously. In this thesis, four series of IrⅢ complexes were synthesized by using different organic chromophores. The photophysical properties and applications of the complexes were studied by steady and transient spectra, as well as DFT calculations.Firstly,2-3and2-4were synthesized by attaching naphthalimide (NI) to ppy or bpy. The absorption of2-3was improved by3-fold at402nm compared to2-1. The low-lying triplet excited states (T1) of2-3and2-4were proved to be triplet excited states (3IL*) of NI while that of2-1was metal to ligand charge transfer triplet excited state (3MLCT*) by transient difference absorption spectra,77K emission spectra and spin density analysis. The application of2-1-2-4in oxygen sensing and TTA upconversion indicated that luminescent O2sensitivity of2-4was improved by156-fold than that of2-1; TTA upconversion quantum yield of14.4%was observed for2-3, whereas the upconversion was neglectable for2-1at the same experimental conditions.Furthermore,3-3and3-4were synthesized by attaching coumarin (cou) to1,10-Phenanthroline (phen) via imidazole (Im). The absorption of3-3was improved by150-fold at466nm compared to3-1at the same wavelength. The T1states of3-3and3-4were proved to be3TL*state while that of3-1was3MLCT*state. The applications in TTA upconversion and photooxidation showed that upconversion quantum yields of21.3%and23.4%were observed for3-3and3-4respectively, whereas the upconversion was neglectable for3-1at the same experimental conditions. The photooxidation rates of3-3and3-4were much faster than3-1and the yields were also improved.In order to study the effects of different linkers between IrⅢ coordination centre and organic chromophore,4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (Bodipy) was attached to bpy to prepare4-2(the meso-pheny1of Bodipy was attached to the IrⅢ coordination centre via π-conjugation linker) and4-3(2-position of π-core of Bodipy was attached to IrⅢ coordination centre via π-conjugation linker). The absorption of4-3was improved by 152-fold at527nm compared to4-1at the same wavelength. The T1states of4-2and4-3were proved to be3IL*state while that of4-1was3MLCT*state. The upconvcrsion quantum yields of4-2and4-3were1.2%and2.8%respectively, whereas the upconversion was neglectable for4-1at the same experimental conditions. The performance of photooxidation with4-2and4-3as photosensitizers was much better than4-1. The experiments results showed that the property of4-3was better than that of4-2.Lastly, perylenebisimide (PBI) was chosed to prepare5-1. Furthermore, with substitution of the bay position of PBI by amino group,5-2was prepared. The absorption of5-1was improved by70-fold at541nm compared to4-1at the same wavelength. The absorption wavelength of5-2is red-shift to669nm. The T1states of5-1and5-2were also proved to be3IL*state by the experiments results. The photooxidation results indicated that photooxidation rates with5-1and5-2as triplet photosensitizers were much faster and the yields were much higher than that with4-1as photosensitizers. |
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