Research And Application Of Fluorescence Probes And Sensors Based On Rare Earth Complexes And Their Nanosheets

Rare earth elements have special luminescent,magnetic and coordination properties and are widely used in the synthesis and research of novel coordination compounds,functional supramolecules,self-assembly systems and Luminescence sensors.Applications in biology include cell imaging,fluorescent response probes,nuclear magnetic resonance imaging,and multiphoton excitation.Rare earth nanosheets not only have a unique structure,but also overcome the shortcomings of the rare earth complexes as unstable,easy to dissolve in organic solvents,and easy to agglomerate and quench.The thesis elaborates on the following aspects:1.Three europium complexes were prepared to detect of bilirubin in the experimental environment.It was found that the three complexes have good detection of bilirubin,and their linearity,sensitivity,and annihilation rate are very excellent.Among these three complexes,we found that the complexes with Htta as the ligand had the highest sensitivity and quenching rate.Combining UV-Vis absorption spectra,excitation spectra,and fluorescence decay curve analysis,the mechanism of complex antenna effect was systematically discussed and a corresponding model was established.At the same time,the practical application of Eu（III）-tta complex probe in medical detection was also explored.2.We obtained inspiration from two-dimensional material graphene to prepare rare earth materials as two-dimensional rare earth nano-sheets.Rare-earth nano-sheets not only can effectively improve the instability of rare-earth complexes,but also have the unique physical properties of nano-sheets.Due to the absence of hydroxyl groups in the oxide nanosheets,the rare earth nanoplates further enhance their luminescence.The resulting nanosheets were found to be effective for detection of bilirubin concentrations.The new bilirubin sensor was prepared by electrophoretic deposition of nanoplates on the surface of conductive glass and modified with polymer membranes.3.A Htta-modified PS-coated Eu³⁺-doped oxide nanosheet was prepared to simultaneously detect molecular oxygen in gases and liquids.Excited at 356 nm excitation light,the nanoplatelet（TTA）/PS sensor increases as the oxygen concentration（or partial pressure）increases,and the luminescence intensity decreases.Through the structure and fluorescence dynamics analysis,the sensitive mechanism of the sensor is discussed.4.Sulfosalicylic acid（SSA）is an excellent ligand for Tb³⁺,which can greatly enhance its emission light intensity.Toxic ion chromate(CrO₄^2-)is present in large quantities in mines and some metal processing plants and has a serious impact on the environment.CrO₄^2-can effectively quench the luminescence of Tb（SSA）₄.The relative intensity of Tb（SSA）₄ is linear with the CrO₄^2-concentration.The correlation coefficient is high and it is very selective for Cr O₄^2-.We synthesized sulphosalicylic acid（SSA）as an intercalation agent and ligand to prepare Tb³⁺-doped hydroxide nanosheets.The prepared SSA modified antimony-doped hydrate nanosheets have a good detection effect on bilirubin and CrO₄^2-and are insensitive to oxygen.