Preparation Characterization And Luminescence Properties Of Rare Earth Core-shell?SiO₂@PHA-Si-RE-L?and Core-shell-Shell Strcture?SiO₂@PHA-Si-RE-L@SiO₂?Organic-inorganic Composites

In this paper,SiO2 microspheres were prepared by the stober method combined with microwave reaction.The amino-modified silica microspheres SiO2-Si-O-Si-(CH2)3NH2(donated as SiO2?NH2)were formed by 3-aminopropyl-triethoxysilane H2N(CH2)3Si(OCH2CH3)3(APTES)grafted onto the surface of silica microspheres by hydrolysis co-polycondensation.Then,SiO2-Si-O-Si-(CH2)3NHCOC6H4COOH(donated as SiO2@PHA-Si)were synthesized successfully by PHA reacted with SiO2@NH2.Four kinds of core-shell type rare earth organic-inorganic composites were synthesized by rare earth perchlorates(samarium,europium,terbium,and dysprosium)coordinated with organic ligand of SiO2@PHA-Si(silica regared as core,and organic complex regared as shell).Besides,second ligand bipyridyl(Dipy)and phenanthroline(Phen)were added to above system to formed eight kinds of ternary core-shell type rare earth organic-inorganic composites SiO2@PHA-Si-RE-L(L=Dipy/Phen).The binary and ternary core-shell type rare earth organic-inorganic composites were characteristed by SEM,TEM,EDX,IR spectra analysis,XPS analysis,ultraviolet spectrum,thermogravimetric analysis,and XRD analysis.It can be observed that the core-shell type rare earth composites were synthesized successfully.The size of core-shell type rare earth organic-inorganic composites were increased and the surface of microspheres become rougher.Further observation EDX analysis,the surface of the core-shell type rare earth organic-inorganic composites existed rare earth element,which indicates that the core-shell type rare earth organic-inorganic composites were synthesized.The characteristic peaks of the organic ligands on the surface of the silica can be observed from the infrared spectra,which further illustrates the formation of binary and ternary core-shell rare earth organic-inorganic composites.XPS analysis shows that C,Cl and RE element exist on the surface of core-shell type rare earth organic-inorganic composites.Thermogravimetric analysis indicates that the core-shell type rare earth organic-inorganic composite has relatively good thermal stability.Fluorescence spectra shows that the binary and ternary core-shell type rare earth organic-inorganic composites have strong fluorescence intensity.The fluorescence intensity of ternary europium composites SiO2@PHA-Si-Eu-Dipy.?SiO2@PHA-Si-Eu-Phen were stronger than binary europium composites Si0O2@PHA-Si-Eu about 4.43 and 2.77 times.The fluorescence intensity of ternary terbium composites SiO2@PHA-Si-Tb-Dipy?SiO2@PHA-Si-Tb-Phen were stronger than binary terbium composites SiO2@PHA-Si-Tb about 7.3 and 10.7 times.The fluorescence intensity of ternary samarium composites SiO2@PHA-Si-Sm-Dipy?SiO2@PHA-Si-Sm-Phen were stronger than binary samarium composites SiO2@PHA-Si-Sm about 7.4 and 7.3 times.The ternary dysprosium composites SiO2@PHA-Si-Dy-Dipy?SiO2@PHA-Si-Dy-Phen were stronger than binary dysprosium composites SiO2@PHA-Si-Dy 2.47 and 1.17 times.A layer of nano-silica coated on the surface of core-shell rare earth organic-inorganic composite(Si0O2@PHA-Si-RE-L(Dipy/Phen)by sol-gel method.12 kinds of core-shell-shell type rare earth organic-inorganic composites(SiO2@ PHA-Si-RE @SiO2?SiO2@PHA-Si-RE-L(Dipy/Phen)@SiO2)were synthesized.The composition of 12 kinds of core-shell-shell type rare earth organic-inorganic composites was determined by TEM,EDX,XRD,IR,TGA and fluorescence spectra.The surface of the core-shell-shell type rare earth organic-inorganic composites become rougher,and the diameter of the microspheres was about 200 nm.Compared with the core-shell type rare earth organic-inorganic composites,the core-shell-shell type rare earth organic-inorganic composites thickness was increased about 10 nm.At the same time,it is observed that the core-shell-shell type rare earth organic-inorganic composites have strong fluorescence intensity.In addition,the fluorescence intensity of rare earth ions in aqueous solution were measurement.The fluorescence intensity were stable in aqueous solution.The twelve kinds of core-shell-shell rare earth organic-inorganic composites labeling with BSA was determined.The fluorescence spectrum of BSA has different degrees of quenching.Fluorescence spectra of rare ions shows that emission intensity were quenched.The experimental results shows that BSA and core-shell-shell rare earth organic-inorganic composites combine to form new composites.