Fluorescence sensing of fluoride ions and N, N- dimethylformamide by novel luminescent lanthanide(III) xerogels

Two novel luminescent lanthanide acylamide derivatives covalently grafted to xerogels (donated as Ln-pp-xerogel, Ln = Eu, Tb) were designed and synthesized in situ via a sol-gel process. The properties of these xerogels were examined by Fourier-transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, thermo-gravimetric analysis, and photoluminescence spectroscopy. The results suggest that the lanthanide derivatives were successfully covalently bonded to the inorganic silica host. The obtained xerogel materials exhibit good thermal stabilities and possess the excellent characteristic luminescence of the corresponding lanthanide ions, which is ascribed to the energy transfer from the organic ligands to the lanthanide ions via an antenna effect. Both the xerogels in acetonitrile solution were used to selective recognition of F⁻ ions and small organic molecule N, N-dimethylformamide by measuring the change in the signal output, which were studied by fluorescence spectroscopy in detail. The sensing mechanisms were studied by the titration of ¹H NMR spectroscopy.