Design,Syntheses And Fluorescent Properties Of Polyoxometalates Besed Micro/nano Materials

Polyoxometalate?POMs? have attracted much attention because of its excellent electron transport capacity,electron storage capacity,special redox potential,and diverse structure types.With the development of nano technique,preparation and research of POMs-base micro-nano materials gradually have become hot.M/NPOM has high efficiency,less environmental pollution,low cost,excellent performance and potential applications in catalysis,material science,biology,medicine and so on.This work will focus on to develop methods and technique to prepare POMs based hybrid materials tunable on size,nanostructure,doping and surface modification,to investigate the relationships between the POMs nano-structural and the chemophysical synthesis.This research will provide abundant new possibilities for the structural diversity and multi-function of M/NPOM materials.Under the direction of correlation theory,being oriented by function,a series of M/NPOM with good properties have been developed through synthesis method,for the purpose of research.The details were shown as follows.Chapter 1:We introduced the nanomaterial as starting point,described organic fluorescent molecules,inorganic fluorescent ions,POMs,and the development significance,synthesis method and application.Chapter 2:Recently,the photoluminescence?PL?property of PNMs has been attracted increasing attention for their wide application potentials.However,compared to other properties of PNMs,there are relatively few studies on photoluminescence properties.The control experiments show that the shape of NCs could be controlled by using different amount of POMs.In addition,POMs could act as electron acceptors to change the PL behavior of materials.Hence,the combination of POMs and fluorescence nanocrystals plays an important role in the application.In this paper,a variety of self-assembled PNMs were developed by hydrothermal method and their properties were investigated based on POMs.Here?-PMo₁₂,?-SiW₁₂ and?-PW₁₂ have been employed to be introduced into CeF₃ NCs,resulting PMo₁₂/CeF₃,SiW₁₂/CeF₃ and PW₁₂/CeF₃ NCs with nanoflower,nanoplates and nanosphere morphologies,respectively.The control experiments show that the shape of NCs could be controlled by using different amount of POMs.Meanwhile,the PL properties of CeF₃ NCs also could be tuned by employing different amounts of POMs.Moreover,POM/CeF₃ has a high catalytic efficiency during exploring its degradation of organic compounds owing to nanometer POM/CeF₃ provides more active sites for adsorbing pollutants due to its high specific surface area.Chapter 3:Organic fluorescent molecules are attracted great attentions due to sensitive signals and multiple applications.In this chapter,a series of organic-inorganic hybrid silicotungstate microtubes bpy-MSiW12?bpy=2,2'-bipydine;M=Mn^?,Fe^?,Co^?,Ni^?,Cu^?? have been successfully synthesized under mild solution conditions by introducing organic ligand,different transition-metals.On the one hand,detailed control experiments reveal that the preparation of SiW₁₂ microtubes can be controlled by changing the type of scratch at the bottom of the flask and the dose of the precursor.On the other hand,the spectroscopic properties of bpy-NiSiW₁₂ were investigated,exhibiting a remarkable blue-shift emission spectrum,corresponding to the photoluminescence of organic molecule.The PL lifetime measurements reveal that the PL lifetime of the bpy-NiSiW12 decreased in comparison with free bpy ligand.Because POMs are easily soluble in water and the microtubs are fragile,which will bring inconvenience for the preservation and application without bpy modification.The burgeoning interests of silica-capped nano/micro composites have been greatly spurred by the excellent silica properties including rich surface chemistry,high biocompatibility,controllable porosity,and good transparency.Although silica has been widely used to coat various nanoparticles,they have seldom been employed as inorganic shell of POM microstructures so far.From this perspective,silica shell came to our attention.Also,it is a general strategy for preparing surface protection and functionalization of POM materials depend on the silica shell and its rich surface chemistry.Chapter 4:The material based on heteropolymolybdate is rarely reported to date after consulting plentiful literature.Hence,the novel morphology and photoluminescence of POM based nano/micro materials is relatively not rich.From these perspectives,phosphomolybdate and sodium fluorescein?denoted as 'FS' for short? came to our attention.On the one hand,FS is a manufactured dye,which is environmentally friendly and inexpensive.It is widely used as a fluorescent tracer for many applications due to its excellent performance.In this report,we explored the synthesis and PL property of FS doped phosphomolybdate microspindle(referred as 'FS-AgPMo₁₂' for short).Interestingly,this material exhibits dual-emission which is extremely rare in POM based nano/micro materials.Upon excitation at 375 nm,the PL spectra of FS-AgPMo₁₂ microspindle were displayed.Interestingly,a dual-emission was observed for FS-AgPMo₁₂ microspindle during our study in distilled water.The emission bands at 467 nm and 512 nm could be observed.