Luminescent xerogels obtained through embedding Tb(III) and Eu(III) complexes in silica matrix

The paper reports the preparation of two luminescent xerogels through embedding in a silica matrix of Tb(III) and Eu(III) complexes using succinimide (SI) and N-hydroxysuccinimide (NHSI) as ligands. In the first stage, Tb(III) and Eu(III) complexes with N-hydroxysuccinimide and succinimide were prepared at 1:3 metal to ligand ratio. Strong luminescent emission was observed only in case of Eu(III)-SI and Tb(III)-NHSI complexes while the Eu(III)-NHSI and Tb(III)-SI complexes exhibited none or weak photoluminescent properties. In the second stage, the selected highly luminescent complexes were embedded in silica matrices via a sol-gel procedure leading to the formation of xerogels with transparent-glassy aspect which keep the remarkable photoluminescence properties of the free complexes. The selected, highly luminescent free complexes and their correspondent silica xerogels were investigated through thermal analysis, powder XRD, SEM, FT-IR and fluorescence spectroscopy. Their excellent photoluminescent properties and excitation spectra, conveniently located in UV-A region, might recommend these materials for applications in optoelectronic devices where photonic conversion layers are required.