| Cyclometalated platinum complexes are a type of important phosphorescent metal complexes,which can be used in organic light-emitting diodes,oxygen sensors,organic photovoltaic cells,biological imaging,probes,and other fields.The structure of the ligands has a significant influence on the properties of the complexes.Therefore,the study of the relationship between the structure of the ligands and the properties of the complexes is of great scientific and practical application for the development of platinum complexes with excellent properties.2,4-diarylquinoline ligands can control the properties of cyclometalated platinum complexes by adjusting the kinds and position of substituents in two benzene ring,from which a series of new platinum complexes can be easily derived.However,due to the limited methods for the efficient synthesis of ligands,there are currently few studies on the platinum complexes of such ligands.Therefore,it is of great value to develop efficient synthesis methods of 2,4diarylquinoline ligands and to study the properties of cyclometalated platinum complexes based on 2,4-diarylquinoline ligands.The main work of this thesis is as following:1.Based on the catalysts controlled regioselective one-pot Suzuki-Miyaura coupling reaction catalyzed by PdCl2(dppf)and NiCl2(dppp)as well as the SuzukiMiyaura coupling reaction catalyzed by NiCl2(dppp)developed previously by our group,a series of 2,4-diarylquinoline ligands containing different substituents on the 2position or 4-position benzene ring were synthesized with the yields ranging from 49%to 80%.Subsequently,these ligands were used for the synthesis of platinum complexes.After optimizing the traditional methods,a series of 2,4-diarylquinoline cyclometalated platinum complexes were successfully obtained through a one-pot method with the yields ranging from 36%to 69%.2.The photophysical and electrochemical properties of these complexes were studied.In dichloromethane solution,these complexes showed obvious low energy absorption band at 370～500 nm,the maximum emission wavelength was in the range of 600～617 nm,the lifetime was in the range of 0.83～1.67 μs,and the luminescent quantum yield was in the range of 0.12 to 0.19.The initial oxidation potential of these complex was between 0.71 V and 0.86 V,and the initial reduction potential was between-1.24 V and-1.52 V.After comparing the kinds of substituents on the 2,4diarylquinoline ligands,it was found that introducing the methoxyl group at the 4’position on the 2-position benzene ring or 4"-position on the 4-position benzene ring of the liangds can make the low energy absorption band and maximum emission wavelength of the cyclometalated platinum complexes blue shift(the maximum shift is 9 nm),and a somewhat lower oxidation and higher reduction potential was observed.On the contrary,the red-shifted low energy absorption and emission bands(the maximum shift is 8 nm)and a higher oxidation and lower reduction potential was observed by the introduction of trifluoromethyl.The position of substituents also has obvious effect for 2,4-diarylquinoline cyclometalated platinum complexes.The introduction of a methoxyl group at the 3’-position on the 2-position benzene ring resulted in red-shifted absorption and emission properties,which is different from the introduction of a methoxyl group at the 4’-position on the 2-position benzene ring.DFT theoretical calculations showed that the difference of HOMO level between them was the main reason.3.We took the complex L1Pt(acac)as an example to explore the application potential of 2,4-diarylquinoline cyclometalated platinum complexes in the detection of hypochlorite.The complex L1Pt(acac)showed excellent "turn off" properties for hypochlorite with high sensitivity,good selectivity and low detection limit of 45.7 nM.The titration experiments revealed that the complexes L3Pt(acac)and L4Pt(acac)displayed very similar sensing ability,the corresponding limits of detection for hypochlorite are 55.9 and 58.8 nM,respectively. |
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