Effect of silver nanoparticles on luminescent properties of europium complex in di-ureasil hybrid materials

Organic-inorganic hybrids containing luminescent lanthanide complex Eu(tta)(3)Phen (tta = thenoyltrifluoroaceton, phen = 1,10-phenanthroline) and silver nanoparticles have been prepared via mixing rare earth complex and nanoparticles with the precursors of di-ureasil using a sol-gel process. The obtained hybrid materials with transparent and elastomeric features were characterized by transmission electron microscope, solid-state Si-29 magic-angle spinning NMR spectra, diffuse reflectance, UV-visible absorption and photoluminescence spectroscopies. The effect of the silver nanoparticles on the luminescence properties was investigated. The experimental results showed that the luminescence intensity of the Eu(tta)(3)phen complex could be enhanced by less than ca. 9.5 nM of silver nanoparticles with the average diameter of 4 nm, and reached its maximum at the concentration of ca. 3.6 nM. Further increasing the concentration of the silver nanoparticles (> 9.5 nM) made the luminescence quenched. The enchancement and quench mechnism was discussed.