Preparation And Luminescence Properties Of H₂O₂ Responsive Carboxylated Curdlan Rare Earth Fluorescence Complexes

The polymer matrix can effectively improve the flexibility,mechanical strength and luminescence performance of the rare earth composite luminescent material.Natural polysaccharides in nature with a rich source are environmentally friendly and have potential development value as a high-quality polymer matrix.In this thesis,curdlan,ethylenediaminetetraacetic acid?EDTA?and nitrilotriacetic acid?NTA?are used as the main raw materials to prepared carboxylated curdlan Cur-EDTA and Cur-NTA,¹³C-NMR,FT-IR and GPC characterization confirmed that the curdlan derivatives have the same backbone structure to curdlan,and were wate-soluble.Used as biopolymer matrix,Cur-EDTA and Cur-NTA can chelated and coordinated with laponite based rare earth(Eu³⁺and Tb³⁺)-DPA complexes?EDL and TDL?in aqueous solution respectively,and generated four kinds of novel composites of carboxylated curdlan and rare earth complex?EDL@Cur-EDTA,EDL@Cur-NTA,TDL@Cur-EDTA and TDL@Cur-NTA?.After their structures and thermal stabilities were confirmed by FT-IR and TGA,employed by UV-vis?FS and CIE chromaticity,the luminescent properties were systematically characterized.The results showed that four composites are colorless and transparent under sunlight,while under UV light,EDL@Cur-EDTA and EDL@Cur-NTA emit bright red light,TDL@Cur-EDTA and TDL@Cur-NTA emit bright green light.Cur-EDTA and Cur-NTA as polymer matrices can enhance the luminous intensity and stability of rare earth complexes,extend the fluorescence life and improve the quantum yield effectively,and the fluorescence intensity and lifetime of Cur-EDTA based composites are better than those based on Cur-NTA.Among them,EDL@Cur-EDTA has the stronger luminous intensity,longer fluorescence lifetime?0.92 ms?and higher quantum yield?63.73%?than that of EDL@Cur-NTA;TDL@Cur-EDTA has greater luminescence intensity and longer life than TDL@Cur-NTA?1.40ms?.In this thesis,using luminescent composites of carboxylated curdlan rare earth complexes as the detection probe,we tested the aqueous solution of H₂O₂ in the concentration ranged from 0 to2000?M,the results displayed that luminescence intensity of EDL@Cur-EDTA,EDL@Cur-NTA,TDL@Cur-EDTA and TDL@Cur-NTA probes are linear negative correlation with the H₂O₂concentration,and the color gradually weakened from bright red or green to complete quenching,and showed the excellent selectivity to H₂O₂.The novel fluorescent composites of carboxylated curdlan and europium and terbium complexes with excellent luminescent properties have been acquired in this thesis,which can be used as highly sensitive and selective H₂O₂ detection probes and have potential application value in the field of fluorescent sensors.