Highly selective fluorescent sensing for fluoride based on a covalently bonded europium mesoporous hybrid material

Abstract

A novel silylated ligand (L–Si) derived from a derivative of phenanthroline (2-(2-hydroxyphenyl)-imidazo[4,5-f]-1,10-phenanthroline, denoted as L) was designed, and it played key roles in the assembly of new organic-inorganic mesoporous hybrid functional material. Firstly, the two N atoms of pyridine rings can coordinate to europium ions and sensitize its luminescence. Secondly, the NH of imidzole ring could form hydrogen bonds with fluoride anions. Thirdly, the silylated group can covalently bonded to the frame of SBA-15 mesoporous silica via in-situ synthesis approach. In addition, 2-thenoyltrifluoroacetonate (TTA) was selected as the second ligand for the purpose of better luminescence. Finally, the europium luminescent mesoporous hybrid material Eu(L–S15)2TTA was obtained through the coordination reaction between europium ion and L–S15 as well as the second ligand TTA. Eu(L–S15)2TTA not only exhibits excellent luminescent properties and high thermal stability, but also retains the ordered mesoporous structures. More importantly, it displays a high-sensitivity sensing function with respect to fluoride ion. The limit of detection for the fluoride ion is as low as 1.6×10−9M for the fluoride ion.