Design And Preparation Of Reversible Red Fluorescent Switch

With the advent of information technology and industrialization,environmental problems and food safety problems are arising in succession.Therefore,it is urgent to seek for a simple and effective means towards the detection of environmental and food safety problems.Among the various detection methods,fluorescent molecular switches own a wide application prospect in the fields of medicine,optics,biology and environmental analysis because of its simple operation,clear-defined phenomenon,low detection limit and high sensitivity.In this thesis,PB@CD/SiO₂ composite,Eu³⁺decorated Ag nanoclusters and WO₃/EuMOF fluorescent switches were prepared.The morphology,elemental and structural composition of the composites were analyzed by characterizations including scanning electron microscopy,energy dispersive X-ray spectroscopy,X-ray diffraction analysis,Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy.The optical properties of the composites and the corresponding devices were further examined by UV-vis absorption spectroscopy and fluorescence spectroscopy.Firstly,prussian blue（PB）and carbon dots（CD）were prepared respectively,and CD-containing SiO₂ layer was coated on PB surface with the assistance of ammonia.Thus,PB@CD/SiO₂ core-shell fluorescent switch was successfully constructed employing PB and CD as quenching and fluorescent agent,and utilized for the effective dual-spectral detection of N₂H₄ and H₂O₂.Next,Eu³⁺was loaded on the surface of Ag nanoclusters to obtain Eu³⁺decorated Ag nanoclusters,which was further investigated for the detection of GSH,Cu²⁺and DPA.Finally,EuMOF red-light emitting film was prepared by cathodic deposition and applied to electrochromic devices,so as to successfully construct WO₃/EuMOF fluorescent switch.By changing the voltage,it can reversibly regulate the coloring and fading of the device color and the quenching and recovery of fluorescence,in order to control the"on"and"off"of the fluorescence switch.In addition,taking the advantages of low detection limit,high sensitivity and short response time,the prepared fluorescent switches have broad application prospects in the research of fluorescent sensors and intelligent windows.