Rare Earth Centered Hybrid Materials: Tb3+ Covalently Bonded with La3+, Gd3+, Y3+ Through Sulfonamide Bridge and Luminescence Enhancement

The organic ligand 5-sulfosalicylic acid (SSA) is grafted by (3-aminopropyl) triethoxysilane (APTES) to achieve functionalized sulfonamide bridge (SSA-Si) which can both coordinate to Ln³⁺ to form luminescent center and link inorganic Si-O network through hydrolysis and condensation reaction with tetraethoxysilane (TEOS). Thus the organic–inorganic hybrid is obtained with sol-gel method. The organic polymer poly-methyl methacrylate (PMMA) acts as another precursor is prepared through the direct addition polymerization of MMA monomer in the presence of the initiator BPO (benzoyl peroxide). The two kinds of precursors are coordinated to the Ln³⁺ simultaneously to form organic–inorganic-polymeric hybrids which contain both inorganic Si-O-Si net and organic periodic C–C chains. In these complicated compounds we intercalate different ratios of Tb³⁺ and inert lanthanide ion (La³⁺, Gd³⁺, Y³⁺) and find that the introduction of the inert lanthanide ions can enhance the luminescence intensity. This enhancement phenomenon is called co-luminescence effect which is studied by emission spectra in this paper.