Study On The Construction And Performance Of Multifunctional Lanthanide Metal Organic Frameworks Of Polycarboxylic Acid Ligands

Lanthanide metal-organic frameworks are another type of porous crystalline material formed by coordination of lanthanide metal ions and organic ligands.It not only has excellent luminescence characteristics of lanthanides,but also includes the porosity,adjustability and diversity of the MOFs structure.So that Ln-MOFs has efficient recognition ability for guest molecules and unique luminescence characteristics.They are extensively employed in many fields such as luminescent materials,chemical sensing,adsorption separation,biological imaging,magnetic and catalysis.Based on existing scientific research results and functional-oriented research ideas of the research group,this paper successfully constructed two novel Ln-MOFs through solvothermal reaction of polycarboxylic acid organic ligands and lanthanide metal salt.The structure and performance have been studied in detail,and the results demonstrate that they can all be used as excellent water-stable multi-response fluorescent sensors to efficiently detect toxic pollutants and have potential applications in adsorption and separation.The full text consists of four parts:1.The background,research status and construction methods of lanthanide metal-organic frameworks is briefly summarized.The application progress of lanthanide metal-organic frameworks in various fields is briefly introduced.2.A new topology type of Ln-MOFs,{[Ln₂?L?₂?H₂O?₂]·5H₂O·6DMAC}_n,[Ln^?=Eu?1?and Tb?2?,DMAC=N,N-dimethylacetamide],has been isolated.Single crystal X-ray diffraction indicates that complexes1-2 is isostructural.Complexes1-2exhibit an excellent luminescent sensing response to inorganic ions Fe³⁺,Cr₂O₇^2-,MnO₄^-and 4-NP,with low detection limit and high Ksv value.Interestingly,when the MnO₄^-were detected,the color of the solid sample is noted to change from yellow to brown,visually indicating luminescence induction,which makes the process of detecting MnO₄^-simpler and more practical.Moreover,by using time-resolved photoluminescence techniques,complexe1 can effectively eliminate background fluorescence interference during detection and improve detection accuracy.3.On the basis of Chapter2,we further explored the application performance of complex1 for the adsorption and separation of organic dyes.Studies have shown that complex1 extremely stable,can efficiently selectively adsorb and separate cationic dye MB without having an adverse effect by other dyes?MO,Rh6G and XO?,and has a certain degree of recycling.The maximum adsorption capacity of MB at room temperature for complex1 is 3886 mg/g,which is the largest value reported so far.This material has potential utilization value in the field of organic dye adsorption and recovery.4.Based on the 5-??pyridine-3-oxy?methyl?isophthalic acid,we successfully obtained a new two-dimensional luminescent Eu-MOFs{[Eu?L??HCOO?]H₂O}_n by solvothermal method.,this material is a water-stable multi-response fluorescence sensor,which can efficiently detect toxic substances Fe³⁺,Cr?VI?and 4-NP.Furthermore,the mechanism for the selective sensing of Fe³⁺,Cr?VI?and 4-NP is also explored,which can mainly be explained by energy competition between the absorption of the analytes and excitation of Eu-MOFs.This work highlights applications of Ln-MOFs as fluorescent sensors,builds coordination polymers by introducing pyridine ligands and provides a supplement for the research for the preparation of water-stable multi-response sensing materials.5.The summary and prospect include the summary of the experimental results of this paper,the analysis of the innovations and deficiencies of the Ln-MOFs prepared in the paper,and the prospects for the development of lanthanide metal-organic frameworks as fluorescent sensors.