Luminescence behavior of sol-gel-derived hybrid materials resulting from covalent grafting of a chromophore unit to different organically modified alkoxysilanes
Ac. Franville et al., Luminescence behavior of sol-gel-derived hybrid materials resulting from covalent grafting of a chromophore unit to different organically modified alkoxysilanes, CHEM MATER, 12(2), 2000, pp. 428-435
The compounds studied in this work are sol-gel-derived organic-inorganic hy
brid materials in which the two components are covalently linked via Si-C b
onds. The organic part is a chromophore group derived from dipicolinic acid
that is functionalized with tri-alkoxysilyl groups; the as-obtained silyla
ted monomers are afterward submitted to complexation with rare-earth ions (
Eu3+, Gd3+) and are used as the siloxane network precursors. The preparatio
n of hybrid materials including covalent grafting and the sol-gel process i
s described, as well as their luminescence properties. Modifications of the
ligand structure (mono- or disubstituted amides) lead to different coordin
ating properties and to variable absorption edges. As a result, the absorpt
ion efficiency or the ability of the chelates to transfer the absorbed ener
gy to Ln(3+) and consequently the quantum yield of the emission are changed
. The major effect of silica is a broadening of the emission peaks, whereas
spectral repartitions and lifetimes are mainly unchanged as compared with
the corresponding organic molecules.