Enhanced Eu3+ Emission in Aqueous Phosphotungstate Colloidal Systems: Stabilization of Polyoxometalate Nanostructures
Contribuinte(s) |
Universidade Estadual Paulista (UNESP) |
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Data(s) |
20/05/2014
20/05/2014
07/09/2010
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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 |