abstract
An organic molecule, (EtO)(3)Si(CH(2))(3)NH(C =O) NH-(CH(2))(12) - NH(C = O) NH(CH(2))(3)Si(OEt)(3), combining urea functionalities and a 12-carbon alkyl chain, underwent sol - gel reactions in the presence of an acid catalyst, a large excess of water and variable amounts of EuCl(3), giving rise to the formation of crystalline hybrids through a self- directed organization process in which hydrogen bonding interactions play a key role. Three photoluminescent lamellar Eu(3+)- doped silsesquioxane hybrids incorporating 1.01, 1.83 and 15.04% Eu(3+) were prepared and fully characterized. The lamellar hybrids are room temperature multi-wavelength emitters due to the convolution of the hybrid's emitting centres and the Eu(3+) intra- 4f(6) transitions. Their emission colour can be easily tuned along the Commission Internationale d'Eclairage chromaticity diagram from the bluish- purple region to the pink area, either by changing the excitation wavelength or the Eu(3+) amount. The Eu(3+) first coordination shell is very similar for the three photoluminescent lamellar Eu3+- doped silsesquioxane hybrids incorporating oxygen atoms of the carbonyl group, Cl atoms and water molecules, despite the minor variations found in the (5)D(0) quantum efficiency ( 16.3 - 19.2), number of water molecules ( 1.7 - 2.0) and experimental intensity Omega(2) parameter (8.9 - 10.1 x 10(-20) cm(2)) with the increase of Eu(3+) content.
keywords
ORGANIC-INORGANIC HYBRIDS; BETA-DIKETONATE COMPLEX; CARBOXYLIC-ACID SOLVOLYSIS; FULL-COLOR PHOSPHORS; LONG ALKYLENE CHAINS; WHITE-LIGHT EMISSION; X-RAY-DIFFRACTION; SOLID-STATE NMR; THIN-FILMS; LUMINESCENCE PROPERTIES
subject category
Chemistry; Materials Science
authors
Nobre, SS; Brites, CDS; Ferreira, RAS; Bermudez, VD; Carcel, C; Moreau, JJE; Rocha, J; Man, MWC; Carlos, LD
our authors
Carlos Brites
Associate Professor
João Rocha
Full Professor
Luís Carlos
Full professor
Maria Rute de Amorim e Sá Ferreira André
Full professoracknowledgements
The support of NoE FAME, Fundacao para a Ciencia e Tecnologia (FCT) (POCI/V. 5/A0067/2005) and FEDER is gratefully acknowledged. The authors would like to thank the collaboration of AG Macedo, Aveiro University, in the AFM measurements and Bruno Caetano and C. Santilli, UNESP, Brazil, during SAXS measurements. S. S. Nobre and C. D. S. Brites thank FCT grants (SFRH/BD/28739/06 and 38472/07, respectively).