Covalently assembly and photophysical properties of novel lanthanide centered hybrid materials by functionalized thioacylureas bridge

A novel molecular precursor (abbreviated as TAM-Si) derives from thioacetaminde (TAM) modified by 3-(triethoxysilyl)-propyl isocyanate (TEPIC) though the hydrogen transfer addition reaction. Then TAM-Si behaves as functional molecular bridge which coordinates to RE³ (Eu³⁺, Tb³⁺) as well as form SiO network with inorganic precursor (TEOS) after a sol–gel process (cohydrolysis and copolycondensation reaction), resulting in the covalently bonded hybrid materials (RE–TAM-Si). On the other hand, the hybrid material of TAM-Si without introduction of RE³⁺ as well has been obtained. SEM pictures indicate that the TAM-Si show the sphere micromorphology with particle size of micrometer dimension while RE–TAM-Si hybrids present different nanometer particle, which suggests that lanthanide ions has influence on the microstructure of hybrid systems through its coordinated effect. The blue emission for TAM-Si hybrids and the narrow-width green and red emissions were achieved for Tb³⁺ and Eu³⁺ ions, respectively, indicating that the intramolecular energy transfer process take place from photoactive group to Tb³⁺ and Eu³⁺ ions in these hybrid microsphere systems. Especially the lifetime and quantum efficiency for europium hybrids have been determined.