A transparent and luminescent ionogel based on organosilica and ionic liquid coordinating to Eu3+ ions

Abstract

Herein we present a facile method to prepare a transparent and luminescent ionogel monolith by hydrolysis and condensation of the silylated bipyridine, which can sensitize the luminescence of europium(III) in the presence of a carboxyl-functionalized ionic liquid where Eu³⁺ ions are coordinated to the oxygen atoms of carboxylate groups from the ionic liquid. FT-IR, TG and photoluminescence spectroscopy were employed to characterize the obtained ionogel. The FT-IR spectrum shows that Eu³⁺ ions are coordinated to the ionic liquid via the oxygen atoms in the ionogel. Excitation and emission spectra verify that the energy transfer from the bipyridine groups (covalently bound to silica) to Eu³⁺ ions occurs. The ⁵D₀ quantum efficiency value and the number of water molecules coordinated to Eu ³⁺ ions in the ionogel have been estimated.