Modulating the Sensing Behavior of Functionalized Mesoporous Silica towards Metal Ions in Aqueous Medium

Abstract

AbstractA rhodamine‐bisphenol A incorporated mesoporous silica (RBA‐IMS) has been synthesized as a turn‐on chemosensor for selective sensing of Al3+, Cr3+ and Fe3+. It has been observed that the presence of an ethylenediamine unit instead of hydrazine, as reported previously, is significant, changing the sensing behavior altogether. The probe does not show any color or absorption band in the visible region and fluorescence in the absence of most of the cations except Al3+, Cr3+ and Fe3+. RBA‐IMS becomes pink with these cations, shows strong absorption at 530 nm and strong fluorescence at 550 nm in 10 mM HEPES buffer in water/methanol=14 : 1 (v/v) (pH 7.0). This is in contrast to the hydrazine‐containing material, which could sense Hg2+ and Cu2+ in aqueous media but not Al3+, Cr3+ and Fe3+. A small change of the linkage in the material suppresses the detection of the divalent cations while enabling the sensing of the trivalent cations in aqueous media.