Phenanthroline derivative based europium(III) covalently bonded silica hybrid material for high-selectivity sensing of anion and small organic molecule

A new polysilsesquioxane bridge (PhenOHSi) was synthesized here using 2-(2-hydroxyphenyl)-imidazo[4,5-f]-1,10-phenanthroline (PhenOH) and 3-(triethoxysilyl)propyl isocyanate respectively as a ligand of Eu3+ ion and a siloxane network precursor. Then, an organic–inorganic hybrid material covalently grafted with an Eu3+ complex (denoted as Eu(PhenOHSi)2Phen) was synthesized by coordination of an Eu3+ ion with a multifunctional precursor PhenOHSi and a second ligand Phen in a sol–gel process. This hybrid material was found to exhibit intensive red luminescence under UV light triggered by the ligand antenna effect. Further luminescent studies indicate that Eu(PhenOHSi)2Phen not only displays high sensitivity sensing targeted at fluoride ions, but also exhibits distinct solvent-dependent luminescent spectra with emission intensities that are significantly quenched by N,N-dimethylformamide.