Improved photoluminescence properties of a novel europium(III) complex covalently grafted to organically modified silicates

A series of novel organic–inorganic hybrid materials with a Eu(III) complex [(C2H5)4N][Eu(DBM)3(DBM-OH)] (DBM = dibenzoylmethanate, DBM-OH = p-hydroxydibenzoylmethanate) covalently bonded into vinyl-modified silica networks have been successfully assembled through a sol–gel process. DBM-OH was grafted to the coupling agent 3-(triethoxysilyl)propylisocyanate (TESPIC), and the as-obtained molecular precursor DBM-Si was used as a bridge molecule both coordinate to Eu3+ and forming an inorganic Si–O network with tetraethoxysilane (TEOS) and vinyltriethoxysilane (VTES) after cohydrolysis and co-condensation processes. The luminescence properties of VTES/TEOS composite hybrid materials were systematically studied in comparison to those of TEOS-derived hybrid material and pure [(C2H5)4N][Eu(DBM)4], respectively. The results indicate that the luminescent quantum efficiencies of VTES/TEOS composite hybrid materials are greatly improved. And it is interesting to find that the luminescent intensity of VTES/TEOS composite hybrid material is enhanced by optimizing the molar ratio of VTES to TEOS (VTES:TEOS = 4:6) by 3.3 and 2.4 times compared with TEOS-derived hybrid material and pure [(C2H5)4N][Eu(DBM)4], respectively. In addition, the thermal stability of the emission was also improved considerably. The results presented in this paper indicate that the use of vinyl-modified silicates as a matrix opens the door to improving the photoluminescence properties of Eu(III) complexes.

Graphical abstractA novel Eu(III) complex has been covalently immobilized by ORMOSILs, and the luminescent intensity and emission quantum efficiency of the composite hybrid materials are improved considerably.Figure optionsDownload full-size imageDownload high-quality image (65 K)Download as PowerPoint slide