Synthesis, Characterzation Fluorescence Properties Of Rare Earth Perchlorate With Phen-Si And Sulphoxide As Well As SiO₂@REL_n Core-Shell Submicrospheres

In this paper, Four solid binary complexes of rare earth perchlorate with5-(N,N-Bis-3-(triethoxysilyl) propylamide)-1,10-phenanthroline (phen-Si) and four solid ternary complexes of rare earth perchlorate with phen-Si as the first ligand and2-carboxyphenyl carboxymethyl sulphoxide (H2L) as the second ligand have been synthesized and characterized. By elemental analysis, coordination titration and TGA-DSC studies, the composition of the binary complexes was suggested as RE (phen-Si)2·(C104)3·5H20(RE=Sm, Eu, Tb, Dy); the composition of the ternary complexes was suggested as RE(H2L)2·(phen-Si)·(ClO4)3·6H2O(RE=Sm, Eu, Tb, Dy; H2L=C6H4(COOH)SOCH2COOH). IR spectra and1HNMR spectra studies indicated that phen-Si bonded with RE3+ions by the nitrogen atom. The second ligand2-carboxyphenyl carboxymethyl sulphoxide bonded with RE3+ions by the oygen atom in sulfinyl group and carboxyl acid. The molar conductivities of the four binary complexes in DMF solution indicated that all of the three CIO4-were not coordinated with RE3+, and the molar conductivities of the four ternary complexes in DMF solution indicated that two ClO4-were not coordinated with RE3+. The fluorescent spectra illustrated that the binary and ternary Sm(Ⅲ)、Eu(Ⅲ)、Tb(Ⅲ)、Dy(Ⅲ) complexes displayed characteristic rare earth ions fluorescence in solid state. Compared with the binary complexes, the ternary complexes of Sm3+、Tb3+and Dy3+exhibited stronger fluorescence. The characteristic emission intensity of the ternary Sm3+complex was1.19times as great as that of the binary Sm3+complex. The characteristic emission intensity of the ternary Tb3+complex was1.56times as great as that of the binary complex. The characteristic emission intensity of the ternary Dy3+complex was1.28times as great as that of the binary complex. Phosphorescent spectra showed that the triplet state energy level of second ligand sulphoxide was higher than the excited state energy level4G5/2of Sm3+and5D4of Tb3+. In ternary system, sulfoxide and phen-Si were able to transfer energy to Sm3+and Tb3+ions together by an efficient way, which made the fluorescence emission of the Sm(Ⅲ) and Tb(Ⅲ) ions in the ternary complexes increasing exponentially. The fluorescent decay curves illustrated that all the rare earth complexes had long fluorescent lifetime. The fluorescent quantum yield of the Eu(Ⅲ) complexes has also been studied.Mono-dispersed SiO2of250and500nm were synthesized and the binary and ternary complexes were coated onto mono-dispersed nano-SiO2through self-assembly with different thickness that expressed as SiO2@RELn. When the ratio of phen-Si/SiO2(d=500nm)/Volume of ethanol was0.1g/0.1g/10ml and when the shell was coated with binary complexes named SiO2(500)@RE-P(65)(RE-P=RE (phen-Si)2·(ClO4)3·5H2O); Correspondingly, when the shell was ternary complexes, it was named SiO2(500)@RE-P-L(100)(RE(H2L)2·(phen-Si)·(ClO4)3·6H2O). When the ratio of phen-Si/SiO2/Volume of ethanol was1g/1g/10ml with the size of the SiO2was500nm and the shell was binary complexes named SiO2(500)@RE-P(15); Correspondingly, when the shell was ternary complexes, it was named SiO2(500)@RE-P-L(20). The binary and ternary Eu(Ⅲ) complexes were directly coated onto mono-dispersed nano-SiO2of500nm named SiO2(500)@Eu-P(20) and Si02(500)@Eu-P-L(20), respectively. The structure of the core-shell was analyzed with SEM、TEM and IR. According to the SEM photographs, these particles were granules with smooth surface and good mono-dispersity. The TEM photographs showed that complexes continuously coated on the nanosized silica and the thickness of the coating layer could be altered by the variation of the ratio of the phen-Si/SiO2/ Volume of ethanol. The fluorescent spectra illustrated that the size of the SiO2spheres、the different complexes and the thickness of the coating layer could affect the fluorescent. The results showed that under the same size of the SiO2spheres, the core-shell submicrospheres with the thicker complexes shell exhibited the stronger fluorescent. When the ratio was the same, the smaller size of the SiO2spheres were, the stronger fluorescent of the core-shell submicrospheres was. All the core-shell submicrospheres displayed stronger characteristic emission intensity than that of the homologous complexes. The fluorescent decay curves illustrated that all the core-shell submicrospheres had long fluorescent lifetime. The fluorescent quantum yield of the Eu(Ⅲ) core-shell submicrospheres has been studied.