Structure and luminescence properties of self-assembled films of lanthanide–polyoxometalates clusters/silica core–shell particles

Abstract

In the paper, the luminescent lanthanide–polyoxometalates (Na 9LnW 10O 36, Ln = Eu, Dy, Sm, noted as LnW 10) were grafted on functional Stöber SiO 2 ultrathin film, resulting in the formation of core–shell structured self-assembled ultrathin film. The SiO 2/LnW 10 films show the characteristic luminescence of lanthanide due to an efficient energy transfer in self-assembly films. Especially, the self-assembly film of SiO 2/EuW 10 show the strong bright red emission in UV light which can be observed by naked eyes. The luminescence behavior of the self-assembled films was studied in comparison with the corresponding solid-state complexes by means of emission and excitation spectra. The luminescence properties of lanthanide (Eu, Dy, Sm)–polyoxometalate could be affected by the formation of self-assembly films, and the electrostatic interactions and chemical graft are responsible for the difference in behavior of the luminescence. SEM pictures show that the hybrid ultrathin films of lanthanide–polyoxometalates/silica particles exhibit the regular and ordered core–shell microstructures.