Preparation And Properties Of Rare Earth Composite System Based On Acetoacetate Curdlan

The organic ligands in rare earth complexes can effectively transfer the absorbed energy to rare earth ions,to sensitize the rare earth ions to emit light.The rare earth complexes not only have the advantages of sharp line emission,long fluorescence life and high color purity of rare earth ions,but also can improve the absorption efficiency of photon energy and photoelectrical properties.In this thesis,two rare earth ion composite luminescence system based on acetoacetate curdlan was studied,which has important practical value for the development of efficient new rare earth fluorescence sensor.Acetoacetate curdlan（CACD）was synthesized by transesterification reaction of tert-butyl acetoacetate and curdlan.The structure of CACD was confirmed by NMR,FT-IR,UV-VIS and XPS.The Luminescence system Tb³⁺@CACD and the bicolor luminescence system Tb³⁺&Eu³⁺@Phen@CACD were prepared by coordination with rare earth Tb³⁺and Eu ³⁺under alkaline conditions.The chemical structure,thermal stability and optical properties of the luminescent materials were systematically studied by FT-IR,XPS,TEM,TGA and FS characterization.The results show that Tb³⁺@CACD can emit bright green fluorescence under excitation of 315 nm UV lamp.The fluorescence intensity showed a linear response to Cu²⁺in the concentration range of 0.2-1.8 m M,with a detection limit of 140μM and good selectivity.The fluorescence color and intensity of Tb³⁺&Eu³⁺@Phen@CACD in the bicolor luminescence system are sensitive to temperature change between 223 K and393 K,and the luminescence gradually changes from green to red with the increase of temperature.Further analysis of average fluorescence lifetime showed that the energy transfer of Tb³⁺（⁵D ₄→⁷ F ₅）→Eu³⁺（⁵ D ₀→⁷F ₂）with the increase of temperature,resulting in the response of fluorescence intensity and color to temperature,which is of great application value for the development of wide range fluorescent thermometers.In this thesis,a novel functional curdlan polymer matrix was synthesized,and two stable and efficient rare earth luminescent materials were developed,which have important technical guidance value for the further development and application of fluorescence sensors.