Construction Of Fluorescence Platform Based On Rare-Earth Complex And Study On Its Sensing Performance

As is well known,the unique electronic structure of rare-earth ions leads to special luminescent properties.However,rare-earth ions generally have weak absorption in the ultraviolet region due to their forbidden f-f transitions,resulting in low fluorescence efficiency.It is reported that there are some strateges to improve its luminescence properties,such as coordination with organic ligands or incorporation into special matrices.Organic ligands form complexes with rare-earth ions.Organic ligands effectively transfer the absorbed energy to the rare-earth central ions through non-radiative transitions,which sensitizes and emits the rare-earth central ions.This process is called"antenna effect".Rare-earth complexes,especially those containing europium and terbium ions,can produce red and green light with high color purity.In recent years,the research on europium and europium complexes has attracted extensive research interest of researchers,and the fluorescence properties have been changed by regulating the structure of organic ligands.Luminescent rare-earth organic complexes have the following advantages:high luminous purity,high luminescence quantum yield,long fluorescence lifetime,large Stokes shift,narrow characteristic emission peaks,and the characteristic peaks of excitation and emission are not affected by the central rare earth ion and the ligand structure.It is of great significance to use rare-earth complex luminescent materials as fluorescent probes to detect ions,small organic molecules,biomarkers and other aspects.At present,the ligands for constructing rare earth complexes usually have fewer coordination groups,which limits the coordination between the ligands and rare earth ions.Therefore,we design and synthesize polycarboxylic acid ligands with rare earth ions to obtain rare earth complexes with good luminescence properties.In this paper,it is divided into two parts:?1?A series of complexes with different proportions,Eu_xTb_1-x-BHM-COOH were synthesized by solvothermal method with BHM-COOH as the ligand.The structure of the complexes was determined by various characterization methods.Comparing the fluorescence properties of Eu_xTb_1-x-BHM-COOH,it is found that the fluorescence intensity of Eu and Tb with molar ratio of Eu:Tb=1:3 is stronger,and the intensity of Eu and Tb are close.Finally,Eu_0.24Tb_0.76-BHM-COOH was selected as the best doping ratio.For the convenience of detection,we cast the complex and PLA solution into a film as a fluorescent platform to detect a variety of metal ions.The results show that the fluorescence platform can recognize Fe³⁺ions quickly in aqueous solution,and the detection limit is as low as 4.47?M.?2?The complex Tb-TCP-COOH was synthesized from the novel flexible polycarboxylic acid ligand TCP-COOH.The structure of the complex crystal was determined by X-ray single crystal diffractometer.At the same time,it was characterized by infrared spectroscopy,XPS and other characterization methods.Similarly,we selected the complex to form a film with PLA matrix for detection,and found that the styrene metabolite phenylglyoxylic acid has a obvious identification effect,which can be quenched80%within 2 minutes.The detection limit is lower than that of the American Conference of Governmental Industrial Hygienists.