MOFs As Fluorescent Sensing Materials For Applicaion In Detection Of Environmental Pllutants

The detection and treatment of environmental pollutants including heavy metal ions and small organic molecules are becoming the focus of society.As a new type of functional materials,metal-organic framework compounds?MOFs?not only have stable microporous structure combined with metal ions and multidentate organic ligands,but also have large specific surface area,adjustable pore functional groups,and controllable framework topology.Science and geometry show application prospects in the fields of catalysis,gas storage and separation,and molecular recognition.In this thesis,MOFs?LMOFs?materials with fluorescent properties are designed and synthesized.By modulating the microporous structure,organic functional groups,and metal sites of the skeleton nodes of MOFs,their structural characteristics and fluorescence properties are combined to make the Aldehydes and Hg²⁺ions are used as analytes for adsorption,immobilization,enrichment and specific recognition by MOFs.By studying the changes in fluorescence performance caused by the interaction of MOFs skeleton with environmental harmful substances such as aldehyde compounds and Hg²⁺ions,the law of detection sensitivity and selectivity is established,and the quantitative relationship between the concentration of pollutants and the fluorescence performance parameters of MOFs is established to achieve High-sensitivity,high-selectivity real-time determination of environmental pollutants that are of greater public concern.In this paper,a solvothermal synthesis of formaldehyde-modified FA/NH₂-UIO-66fluorescent MOFs compounds and red-emitting Eu-BDC MOFs compounds was performed.By characterizing their structure and fluorescence properties,the fluorescence sensing effects on aldehydes?formaldehyde,acetaldehyde and glyoxal?and Hg²⁺ions were studied and main tasks as follows:1.FA/NH₂-UIO-66 and Eu-BDC were synthesized by solvothermal method and characterized by XRD,FTIR,and fluorescence spectroscopy.FA/NH₂-UIO-66 and Eu-BDC with good thermal and chemical stability was obtained,and can emit a certain fluorescence intensity,can be used as a fluorescent sensing material;2.FA/NH₂-UIO-66 and Eu-BDC were analyzed by ligand fluorescence,It is preliminarily judged that the luminescence mechanism of FA/NH₂-UIO-66 is based on the emission of the ligand,and there is a charge transfer between the ligand and the rare earth Eu³⁺ion in the Eu-BDC material,which is the"antenna effect".3.The FA/NH₂-UIO-66 was studied by ion fluorescence sensing,and it was found that FA/NH₂-UIO-66 has a very strong fluorescence enhancement reaction to Hg²⁺ions,which can be used for the fluorescence enhancement detection of Hg²⁺ions.Through interference ion experiments,it was found that Pb²⁺,Cd²⁺,Cr³⁺,Al³⁺,Cu²⁺,Fe³⁺,Mg²⁺and other ions have very little interference on FA/NH₂-UIO-66 detection of Hg²⁺ions.Investigate the mechanism of detection of Hg²⁺ions,and preliminarily judge that FA/NH₂-UIO-66 has high selectivity to Hg²⁺ions.Because of the strong nucleophilic properties of imines,Hg²⁺can easily bind to imines.Conducive to the formation of rings,resulting in increased molecular rigidity,changes in the lowest electronic excited state,and enhanced fluorescence.4.Eu-BDC was used to study the fluorescence sensing of aldehydes.The experiment found that the fluorescence of Eu-BDC can be changed by aldehyde compounds,but the fluorescence intensity of Eu-BDC is different for different aldehyde compounds.It was found that Eu-BDC can detect formaldehyde,acetaldehyde and ethylene glycol very well.Three small organic molecules of aldehyde.Among them,Eu-BDC was found to have a slight fluorescence quenching in formaldehyde,and fluorescence was completely quenched in acetaldehyde.In glyoxal,the red light emission peak around616 nm was completely quenched,and there was a strong intensity blue fluorescence enhancement at 410 nm.