Highly Photostable Luminescent Poly(-caprolactone)siloxane Biohybrids Doped with Europium Complexes
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- 作者：M. Fernandes ; V. de Zea Bermudez ; R. A. Sá ; Ferreira ; L. D. Carlos ; A. Charas ; J. Morgado ; M. M. Silva ; M. J. Smith
- 刊名：Chemistry of Materials
- 出版年：2007
- 出版时间：August 7, 2007
- 年：2007
- 卷：19
- 期：16
- 页码：3892 - 3901
- 全文大小：181K
- 年卷期：v.19,no.16(August 7, 2007)
- ISSN：1520-5002
文摘
In this paper, we propose for the first time that the combination of a sol-gel derived diurethane cross-linked siloxane-based biohybrid host including short poly(
-caprolactone) segments (PCL(530)) andlanthanide aquocomplexes incorporating 
-diketonate ligands yields an effective protecting cage thatefficiently encapsulates the emitting centers and reduces luminescence quenching. The results obtainedusing the Eu(tta)3(H2O)2 (where tta- is 2-thenoyltrifluoracetonate) complex demonstrate that 1 (2) carbonyloxygen atoms of the host matrix enter the Eu3+ coordination shell, thus replacing the labile water molecule(s). The significant increase in the quantum efficiency q of the doped hybrid with respect to that ofEu(tta)3(H2O)2 (44.2 versus 29.0%, respectively) reveals that complex anchoring to the PCL(530)-basedhost structure contributes to enhancement of the 5D0 quantum efficiency. However, when a complex thatcontains only strong chelating ligands, such as Eu(tta)3phen (where phen is 1,10-phenantroline), isincorporated into the same host medium, the effect is lost and the 5D0 nonradiative paths in the dopedhybrid are higher than those existing in the complex itself. Under UVA exposure, the emission intensityof PCL(530)/siloxane/Eu(tta)3(H2O)2 decreased 10% in 11 h, whereas that of PCL(530)/siloxane/Eu(tta)3phen decreased 25% in the same period of time.
-caprolactone) segments (PCL(530)) andlanthanide aquocomplexes incorporating -diketonate ligands yields an effective protecting cage thatefficiently encapsulates the emitting centers and reduces luminescence quenching. The results obtainedusing the Eu(tta)3(H2O)2 (where tta- is 2-thenoyltrifluoracetonate) complex demonstrate that 1 (2) carbonyloxygen atoms of the host matrix enter the Eu3+ coordination shell, thus replacing the labile water molecule(s). The significant increase in the quantum efficiency q of the doped hybrid with respect to that ofEu(tta)3(H2O)2 (44.2 versus 29.0%, respectively) reveals that complex anchoring to the PCL(530)-basedhost structure contributes to enhancement of the 5D0 quantum efficiency. However, when a complex thatcontains only strong chelating ligands, such as Eu(tta)3phen (where phen is 1,10-phenantroline), isincorporated into the same host medium, the effect is lost and the 5D0 nonradiative paths in the dopedhybrid are higher than those existing in the complex itself. Under UVA exposure, the emission intensityof PCL(530)/siloxane/Eu(tta)3(H2O)2 decreased 10% in 11 h, whereas that of PCL(530)/siloxane/Eu(tta)3phen decreased 25% in the same period of time.