Synthesis, Characterzation Fluorescence Properties Of Rare Earth Perchlorate With Phen-Si And TTA Or Dipy As Well As SiO₂@（L）_n-RE Core-Shell Submicrospheres

In this paper, eight solid ternary complexes of rare earth perchlorate were synthesized successfully and characterized comprehensively, which were prepared by using 5-(N,N-Bis-3-(triethoxysilyl)propyl)urey1-1,10-phenanthroline (phen-Si) as first ligand and TTA or Dipy as second ligand. Besides,16 novel rare-earth core-shell hybrid materials of Sm(Ⅲ)、Eu(Ⅲ)、Tb(Ⅲ) and Dy(Ⅲ) were prepared successfully by using SiO2 microspheres with different sizes as core prepared by Stober method, which would be modified by phen-Si, then adding second ligand and RE(Ⅲ) ion to make ternary complex forming in the shell of core-shell hybrid materials. Simple ternary complexes and core-shell hybrid materials made a series of characterization and the comparison of fluorescence properties. All complexes and core-shell hybrid materials showed good fluorescence properties and the fluorescence intensity of core-shell hybrid materials were greater than the corresponding simple ternary complexes.By C、H、N elemental analysis, coordination titration and TGA-DSC studies, the composition of the ternary complexes of TTA was to be RE (phen-Si)·(TTA)2· (ClO4)3·6H2O (RE= Sm, Eu, Tb, Dy), while Dipy was as second ligand, RE(phen-Si)·(Dipy)2·(ClO4)3·6H2O (RE= Sm, Eu, Tb, Dy), IR spectra and’HNMR spectra studies indicated that phen-Si bonded with RE3+ ions by the nitrogen atom, while TTA and Dipy was with the oxygen atom of C=O and nitrogen atom of C=N, respectively.The molar conductivities of the eight 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+ and Eu3+ exhibited stronger fluorescence. In ternary complexes of TTA, the characteristic emission intensity of the ternary Sm3+ complex was 1.80 times as great as that of the binary Sm3+ complex. The characteristic emission intensity of the ternary Eu3+ complex was 3.44 times as great as that of the binary complex. While in ternary complexes of Dipy, the characteristic emission intensity of the ternary Sm3+ complex was 1.59 times as great as that of the binary Sm3+ complex. The characteristic emission intensity of the ternary Eu3+ complex was 2.85 times as great as that of the binary complex. In ternary system, TTA, Dipy and phen-Si were able to transfer energy to Sm3+ and Eu3+ ions together by an efficient way, which made the fluorescence emission of the Sm (Ⅲ) and Eu (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 SiO2 of 350 and 550 nm were synthesized and the binary and ternary complexes were coated onto mono-dispersed nano-SiO2 with different thickness that expressed as SiO2@(L)n-RE. The shell was coated with binary complexes of 550nm SiO2 core illustrated with SiO2(550)@L-RE(40) (L=phen-Si) and the thick of shell was 40nm, while ternary complexes was named SiO2(550nm)@L-RE-L’(50)(L=phen-Si, L’=TTA, Dipy), and the thick of shell was 50nm. When the core was 350nm SiO2, the hybrid materials were illustrated with SiO2(350)@L-RE(40) (L=phen-Si) and the thick of shell was 40nm, while ternary complexes was named SiO2(350nm)@L-RE-L’(50)(L=phen-Si, L’=TTA, Dipy), the thick of shell was 50nm. 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 with different thickness of the coating layer. The fluorescent spectra illustrated that the size of the SiO2 spheres、the different complexes and the thickness of the coating layer could affect the fluorescent. The results showed that under the same size of the SiO2 spheres, the core-shell submicrospheres with the thicker complexes shell exhibited the stronger fluorescent. 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.