Novel luminescent lanthanide complexes covalently linked to a terpyridine-functionalized silica network

Novel luminescent organic–inorganic hybrid materials consisting of lanthanide (Eu3+, Tb3+) complexes covalently bonded to a silica-based network have been obtained by a sol–gel approach. A new monomer has been synthesized by the thiol-ene photopolymerization between γ-mercaptopropyltrimethoxysilane and 4′-allyloxy-2,2′:6′,2″-terpyridine. The monomer is afterward submitted to complexation with lanthanide ions and used as the siloxane network precursor. FT-IR, DR, SEM, luminescence spectra and decay analysis, as well as luminescence quantum yields, were used to characterize the obtained hybrid materials. Excitation at the ligand absorption wavelength (333 nm) resulted in strong emission of the lanthanide ions: Eu3+ 5D0–7FJ (J = 0–4) and Tb3+ 5D4–7FJ (J = 6, 5, 4, 3) emission lines due to efficient energy transfer from the ligands to the lanthanide ions. When the Eu3+ and Tb3+ ions were incorporated into the same hybrid material, only the simple addition spectra from the two metal centers was observed, which indicated bimetallic complex was not formed.