A luminescent tris(2-thenoyltrifluoroacetonato)europium(III) complex covalently linked to a 1,10-phenanthroline-functionalised sol–gel glass

Lanthanide doped sol–gel glasses are an attractive type of luminescent material which can be processed at ambient temperatures. However, the solubility of the lanthanide complexes in the sol–gel matrix can be a problem and it is difficult to obtain a uniform distribution of the complexes (avoidance of cluster formation). These problems can be solved by covalently linking the lanthanide complex to the glass matrix. In this study, a strongly luminescent europium β-diketonate complex was immobilized on a 1,10-phenanthroline-functionalised silica sol–gel glass. The glass matrix was prepared by first reacting 5-amino-1,10-phenanthroline with 3-(triethoxysilyl)propyl isocyanate. The resulting compound, tetramethoxysilane (TMOS) and diethoxydimethylsilane (DEDMS) were hydrolysed and condensed at a neutral pH to a sol–gel glass. A tris(2-thenoyltrifluoroacetonato)europium(III) dihydrate complex was bound to the 1,10-phenanthroline groups on the silica gel and the coordinated water was expelled. High-resolution luminescence spectra were recorded and the radiative lifetimes were measured. It is shown that the spectroscopic behaviour of the luminescent materials is very comparable with that of the pure [Ln(tta)3(phen)] complex.