Tris(4-formyl phenyl)amine functionalized mesoporous silica for selective sensing of Al3+ and its separation

Abstract

Modification of a solid support with a suitable organic moiety offers an opportunity for simultaneous detection and removal of an analyte. Here, functionalized mesoporous silica (FMS-TPA-en) has been synthesized with SBA-15 silica as the solid support by successive functionalization of the inorganic mesoporous silica framework with 3-aminopropyl triethoxysilane, tris(4-formyl phenyl)amine and ethylenediamine. The materials in successive stages have been characterized in the solid state using powder X-ray diffraction, nitrogen adsorption/desorption and electron microscopic studies, FT-IR spectra and thermogravimetric analysis. Photoluminescence studies of the material reveal that it is able to sense Al3+ ion selectively among other relevant cations in methanol. Fluorescence of FMS-TPA-en increases at 470 nm upon excitation at 390 nm in the presence of the trivalent cation. It has also been observed that the intensity of the functionalized material remains unchanged in the presence of most of the other relevant metal ions. Here, the combination of tris(4-formyl phenyl)amine and ethylenediamine moieties acts as the fluorophoric units having binding pocket for the binding of metal ion(s). Fluorescence enhancement occurs via PET and CHEFF mechanisms. It has also been observed that the binding of the probe to Al3+ is reversible in nature. FMS-TPA-en has been used for the separation of Al3+ with high efficiency and the solid probe could be easily recycled.