Photoluminescence properties of terbium complexes bound to amorphous silica

Terbium ions were introduced in SiO2 via two different pathways: (1) grafting the terbium europium complexes with two alcoxide structures, 3-(2-imidazolin-1-yl)-propyl-triethoxysilane (IPTES) and aminopropyl-trimethoxysilane (APTMS) and (2) functionalization of the SiO2 support with silicon 4-carboxylbutyltriethoxide (CABES) followed by subsequent addition of the terbium ions. The new materials were investigated by means of nitrogen adsorption isotherms at −196 °C, thermogravimetric analysis, powder X-ray diffraction, Fourier-transform infra-red, diffuse reflectance , steady-state and time-resolved photoluminescence spectroscopy. Terbium complexes are heterogeneous distributed within silica framework and show relatively strong luminescence and long average photoluminescence lifetimes. The non-radiative deactivation of terbium emission in Tb-CABES/SiO2 is more efficient compared to Tb-APTMS /SiO2 and Tb-IPTES/SiO2 and this is reflected in the order of the average photoluminescence lifetimes: Tb-CABES/SiO2 (675 ± 10 μs) < Tb-IPTES/SiO2 (1040 ± 20 μs) < Tb-APTMS/SiO2 (1265 μs ± 25 μs).