| In this paper,5-N-bis(amidopropyl triethoxy silyl)nicotinic acid(HOOCC5H4NN(CONH(CH2)3Si(OCH2CH3)3)2,abbreviated as ANA-Si)was first prepared.The mono-dispersed SiO2 microsphere was synthesized by the Stober method combined with a microwave reaction method,which has a diameter of 200nm.The first ligand ANA-Si was coated on the surface of the mono-dispersed SiO2 microsphere and coordinated with the rare earth ions,then four binary core-shell rare earth organic-inorganic composites were prepared(abbreviated as SiO2@ANA-Si-RE,RE=Sm,Eu,Tb,Dy).Then the second ligand phen and TTA were added to coordinated with the rare earth ions,eight ternary core-shell rare earth organic-inorganic composites(abbreviated as SiO2@ANA-Si-RE-L,L=phen,TTA)were prepared.The SEM and TEM clearly indicated that the binary and ternary core-shell structure composites have been successfully synthesized,which surface layer has a diameter of 15?20nm.EDS and EDX analysis confirmed the existence of rare earth ions,which gives experimental evidence for the rare earth organic complexes successfully coating on the surface of mono-dispersed SiO2 microspheres.TGA analysis showed that the composite had good thermal stability.Luminescence properties demonstrated that most ternary core-shell structure rare earth organic-inorganic composites have stronger luminescence intensity than that of the binary core-shell structure rare earth organic-inorganic composites.The strongest emission intensity of the ternary core-shell structure rare earth organic-inorganic composites SiO2@ANA-Si-Sm-phen and SiO2@ANA-Si-Sm-TTAwere 1.43 and 2.00 times stronger than the binary core-shell structure SiO2@ANA-Si-Sm composite;The strongest emission intensity of the ternary core-shell structure rare earth organic-inorganic composites SiO2@ANA-Si-Eu-phen and SiO2@ANA-Si-Eu-TTA were 4.10 and 1.04 times stronger than the binary core-shell structure SiO2@ANA-Si-Eu composite;The strongest emission intensity of the ternary core-shell structure rare earth organic-inorganic composites SiO2@ANA-Si-Tb-phen and SiO2@ANA-Si-Tb-TTA were 2.10 and 1.85 times stronger than the binary core-shell structure SiO2@ANA-Si-Tb composite.The strongest emission intensity of the ternary core-shell structure rare earth organic-inorganic composites SiO2@ ANA-Si-Dy-phen was 1.08 times stronger than the binary core-shell structure SiO2@ANA-Si-Dy composite,but the mission intensity of the ternary core-shell structure rare earth organic-inorganic composites SiO2@ AN A-Si-Dy-phen was quenched.The low temperature phosphorescence spetra indicated that the ligands ANA-Si,phen,TTA can transfer the energy to the rare earth ions Sm3+,Eu3+,Tb3+ effectively and further to increase their luminescence intensity The luminescence lifetime decay curves and fitting curves showed that Eu3+and Tb3+ have a longer luminescence lifetime.We found that stronger fluorescence intensity often lead to a longer fluorescence lifetime.At the same time,the luminescence quantum yield of europium core-shell composites displayed that the binary core-shell structure SiQ2@ANA-Si-Eu composite has the highest luminescence quantum yield of 28.71%.Four binary core-shell-shell rare earth organic-inorganic composites(abbreviated as SiO2@ANA-Si-RE@ SiO2 RE=Sm,Eu,Tb,Dy)and eight ternary core-shell-shell rare earth organic-inorganic composites(abbreviated as SiO2@ANA-Si-RE-L@SiO2,L=phen,TTA)were first synthesized in this paper.The as-synthesized products were characterized by means of infrared spectroscopy(IR),X-ray diffraction(XRD),scanning electron microscopy(SEM)and transmission electron microscopy(TEM).In the IR spetra of SiO2@ AN A-Si-RE @SiO2 and SiO2@ANA-Si-RE-L@SiO2,comparing the spectra of SiO2 @ ANA-Si-RE and SiO2@ANA-Si-RE-L(L=phen,TTA),the characteristic absorption peaks of the ligands ANA-Si,phen and TTA become weaker and the characteristic absorption peaks of SiO2 become stronger.The SEM and TEM images indicated that the core-shell-shell rare earth organic-inorganic composites were prepared successfully,and the thickness of the SiO2 shell is 15nm.TGA analysis showed that the composite had good thermal stability.Luminescence properties demonstrated that all core-shell-shell rare earth organic-inorganic composites have higher Luminescence intensity than that of the core-shell rare earth organic-inorganic composites.The strongest emission intensity of Sm,Eu,Tb,Dy of the binary core-shell-shell rare earth organic-inorganic composites were 1.29,2.28,1.42,and 1.32 times stronger than that of the binary core-shell rare earth organic-inorganic composites,respectively.The strongest emission intensity of Sm,Eu,Tb,Dy of the ternary core-shell-shell SiO2@ANA-Si-RE-phen@SiO2 rare earth organic-inorganic composites were 2.38,3.14,1.38,and 1.04 times stronger than that of the ternary core-shell SiO2@ANA-Si-RE-phen rare earth organic-inorganic composites,respectively.The strongest emission intensity of Sm,Eu,Tb,Dy of the ternary core-shell-shell SiO2@ANA-Si-RE-TTA@SiO2 rare earth organic-inorganic composites were 5.92,2.51,1.70 and 3.02 times stronger than that of the ternary core-shell SiO2@ ANA-Si-RE-TTA rare earth organic-inorganic composites.The luminescence lifetime decay curves and fitting curves of core-shell-shell rare earth organic-inorganic composites showed that Eu3+ and Tb3+ have a longer luminescence lifetime.And SiO2@ANA-Si-Eu-phen@SiO2 has the longest luminescence lifetime,which was 657?s.Simultaneously,the luminescence stability of twelve core-shell-shell rare-earth organic-inorganic composites aqueous solutions was also studied.The luminescence intensity of the rare earth core-shell-shell composites aqueous solution is almost unchanged after Oh,16h and 40h,which demonstrated that the the rare earth core-shell-shell composites aqueous solution has good luminescence stability.The luminescence quantum yield of europium core-shell-shell composites displayed that the ternary core-shell-shell SiO2@ANA-Si-Eu-TTA@SiO2 rare earth organic-inorganic composites has the highest luminescence quantum yield of 33.81%.In this paper,the twelve core-shell-shell rare-earth organic-inorganic composites luminescence labeling with bovine serum albumin(BSA)was were also studied.The luminescence intensity of the core-shell-shell rare-earth organic-inorganic composites were quenched.However,the characteristic emission peaks of rare earth ions are all existence.These experimental results showed that the europium and terbium series core-shell-shell composites combine with BSA. |
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