Lanthanopolyoxotungstates in silica nanoparticles: multi-wavelength photoluminescent core/shell materials
authors Granadeiro, CM; Ferreira, RAS; Soares-Santos, PCR; Carlos, LD; Trindade, T; Nogueira, HIS
nationality International
journal JOURNAL OF MATERIALS CHEMISTRY
keywords 3-HYDROXYPICOLINIC ACID; FLUORESCENT NANOPARTICLES; LANTHANIDE COMPOUNDS; SHELL NANOSPHERES; ENERGY-TRANSFER; QUANTUM DOTS; COMPLEXES; LUMINESCENT; POLYOXOMETALATE; ANION
abstract Photoluminescent lanthanopolyoxotungstate core/shell nanoparticles are prepared by the encapsulation of lanthanide-containing polyoxometalates (POMs) with amorphous silica shells. The preparation of morphological well-defined core/shell nanoparticles is achieved by the hydrolysis of tetraethoxysilane in the presence of POMs using a reverse microemulsion method. The POMs used are decatungstolanthanoates of [Ln(W(5)O(18))(2)](9-) type (Ln(III) = Eu, Gd and Tb). Photoluminescence studies show that there is efficient emission from the POM located inside the SiO(2) shells, through excitation paths that involve O --> Eu/Tb and O --> W ligand-to-metal charge transfer. It is also shown that the excitation of the POM containing europium(III) may be tuned towards longer wavelengths via an antenna effect, by coordination of an organic ligand such as 3-hydroxypicolinate. The POM/SiO(2) nanoparticles form stable suspensions in aqueous solution having the advantage of POM stabilization inside the core and the possibility of further surface grafting of chemical moieties via well known derivatization procedures for silica surfaces. These features together with the possibility of tuning the excitation wavelength by modifying the coordination sphere in the lanthanopolyoxometalate, make this strategy promising to develop a new class of optical bio-tags composed of silica nanobeads with multi-wavelength photoluminescent lanthanopolyoxometalate cores.
publisher ROYAL SOC CHEMISTRY
issn 0959-9428
year published 2010
volume 20
issue 16
beginning page 3313
ending page 3318
digital object identifier (doi) 10.1039/b919691a
web of science category Chemistry, Physical; Materials Science, Multidisciplinary
subject category Chemistry; Materials Science
unique article identifier WOS:000276373500027

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