Enhanced Eu3+ Emission in Aqueous Phosphotungstate Colloidal Systems: Stabilization of Polyoxometalate Nanostructures


Autoria(s): Barbosa, A. J.; Maia, L. J. Q.; Montanari, B.; Goncalves, R. R.; Messaddeq, Younes; Ferreira, R. A. S.; Carlos, L. D.; Ribeiro, Sidney José Lima
Contribuinte(s)

Universidade Estadual Paulista (UNESP)

Data(s)

20/05/2014

20/05/2014

07/09/2010

Resumo

Luminescent Eu3+-containing polyphosphate tungstate aqueous colloidal systems were prgared and studied as a function of the relative polyphosphate tungstate content. In polyphosphate-rich solutions, Eu-H- ions occupy cagelike sites composed of phosphate groups from the metaphosphate chains. In these sites, an average number of 0.5 water molecule coordinates to an Eu3+ ion and the 500 emission quantum efficiency is 0.22. Tungstatc addition leads to important modifications in neighboring Eu3+ leading to coordination sites in the aqueous medium where metal ions are completely hidden from interactions with solvent molecules. Transmission electron microscopy results clearly show \V-rich nanoparticles with sizes between 5 and 10 nm for all tungstate relative concentrations. For high tungstatc relative contents (above 30 mol %), spectroscopic results suggest the presence of Eu34- in polyoxometalate (P0M)-like sites by comparison with the well-known decatungstoeuropate [EuW10O36](9-) structure. These new aqueous colloids display surprisingly high 5llo emission quantum efficiencies of ca 80% because of the strong ligand field provided by tungstate POM ligands and the complete absence of water molecules from the Eu3+ first coordination shell.

Formato

14170-14176

Identificador

http://dx.doi.org/10.1021/la100525h

Langmuir. Washington: Amer Chemical Soc, v. 26, n. 17, p. 14170-14176, 2010.

0743-7463

http://hdl.handle.net/11449/40378

10.1021/la100525h

WOS:000281354000062

Idioma(s)

eng

Publicador

Amer Chemical Soc

Relação

Langmuir

Direitos

closedAccess

Tipo

info:eu-repo/semantics/article