Study On The Synthesis And The Luminescent Properties Of Zn-MCM-41Mesoporous Materials Containg Rare Earth Complex

Rare earth complexe is important luminescent materials, but it’s biggest drawbackis the poor thermal stability, mesoporous materials have the attractive features, whichare ordered mesoporous structure, large surface area, tunable and uniformitarian poresize, good thermal stability and good chemical stability. Rare-earth compoundmesoporous hybrid materials were obtained through that the rare earth compound dopedinto the holes of mesoporous materials. Mesoporous materials have influence on theluminescence intensity and thermal stability of the rare earth complexe owing to thedoughty interaction between the host and the guest. Rare earth complexes wereassemblied into the channels of mesoporous materials, the composite materials can getthe characteristics of the two materials, then they will have a broader prospect inapplication.In this paper, the high quality mesoporous molecular sieves Zn-MCM-41andMCM-41were firstly synthesized in alkaline medium by the microwave radiationone-pot method. Rare earth complexe Eu(Sal)3phen and Dy(Sal)3phen were obtainedthrough low temperatyre ethanol solution method. The physicochemical properties ofthe samples were well characterized by X-ray diffraction (XRD), fourier transforminfrared spectroscopy (FT-IR), thermogravimetric analysis (DTA-TGA), energydispersive X-ray spectroscopy (EDS), N2adsorption-desorption and scanning electronmicroscopy (SEM). Rare earth complexes Eu(Sal)3phen and Dy(Sal)3phen weresynthesized with in ordered mesoporous materials Zn-MCM-41and MCM-41by usingwet impregnation technique. This investigation is mainly directed to the influence of theZn-MCM-41in the luminescent properties and thermal stability of the rare earthcomplex.Experiment result indicate: the mesoporous materials of the Zn-MCM-41andMCM-41was synthesized by microwave assisted hydro thermal method.2.5h wasoptimum microwave time to obtain high-quality mesoporous materials Zn-MCM-41.When Zn-MCM-41(Zn/Si atomic ratio≤0.06), the high range powder XRD patternsof the Zn-MCM-41materials are shown characteristic absorption band of ZnO, WhenZn-MCM-41(Zn/Si atomic ratio≥0.08), according to the XRD, EDS and N2adsorption-desorption analysis results, zinc reached a certain quantity, the Zn (radius=0.074nm) atoms penetrated into the framework and replaced the Si (radius=0.041nm) atoms. Compare the peak intensity of the three diffraction band between2θ=2-8°inthe XRD patterns of materials Zn-MCM-41, indicating that a further increase in thezinc loading up to higher zinc content produced the deterioration of the long-rangeorder.Rare earth complexe Eu(Sal)3phen and Dy(Sal)3phen were prepared by lowtemperatyre ethanol solution method, europium and dysprosium as central ion,ortho-oxybenzoic acid as the ligand, phenanthroline as the second ligand. Thefluorescence emission spectra of Eu(Sal)3Phen and Dy(Sal)3Phen show the fluorescencecharacteristic peak of of europium and dysprosium. In this study, the organic ligand ofEu(Sal)3phen and Dy(Sal)3phen was the same, but the fluorescence intensity ofEu(Sal)3phen was high than the fluorescence intensity of Dy(Sal)3phen, and thecrystallinity of Eu(Sal)3phen was better than the Dy(Sal)3phen rare earth complexes.Mesoporous material MCM-41and Zn-MCM-41as the host and rare earthcomplexe as the guest prepared rare-earth compound mesoporous hybrid materials.Mesoporous material MCM-41was the best host, compared with other rare-earthcompound mesoporous hybrid materials, the fluorescence intensity of Eu(Sal)3phen/MCM-41and Dy(Sal)3phen/MCM-41materials were the strongest. The fluorescenceintensity was decreased along with increasing zinc content (Zn/Si=0.02-0.1) in theZn-MCM-41mesoporous materials, these because the energy transfer did not occurbetween rare earth central ion and ZnO, and when Zn atoms penetrated into theframework, the structure of mesoporous materials were changed, then the fluorescenceintensity of rare-earth compound mesoporous hybrid materials were decreased. Thethermal stability of rare-earth compound mesoporous hybrid materials was improvedsignificantly compared with the pure rare earth complexes.