An easy way to prepare reusable rhodamine-based chemosensor for selective detection of Cu2+ and Hg2+ ions

Abstract

Abstract Herein, a simple route was demonstrated for preparation of reusable spherical solid supported rhodamine-based chemosensor and its sensing ability toward metal ions were investigated. First, as solid-support material, aldehyde functional spherical crosslinked Poly (vinyl benzaldehyde-co-divinylbenzene) (P(VBA-co-DVB)) microbeads with a particle size of 2-5 μm were synthesis via precipitation polymerization. Rhodamine hydrazide was then attached to the reachable aldehyde groups (3.05 mmol/g) via imine linkages onto the microbeads. Resulting densely crosslinked almost uniform microspheres with a small particle size can be easily dispersed in any solvent and handled easily during the whole recycling process due to the crosslinked nature of the microbeads. All these features make the rhodamine tethered microspheres an ideal fluorescence chemosensor candidate for the detection of analytes in any solvent. The sensing studies against metal ions revealed that the microspheres show high selectivity and sensitivity fluorescence turn-on and colorimetric response towards Hg2+ and Cu2+ ions compare to the other competitor ions in CH3CN: H2O (v/v: 80/20, pH: 7.2) medium. The association constant (Ka) was determined from Benesi-Hildebrand graphics for the microsphere with Hg2+ and Cu2+. Furthermore, the detection limit of the chemosensor was calculated 3.90 x10-7 and 5.06 x10-7 M for Hg2+ and Cu2+, respectively. The fluorescence lifetime of the rhodamine tethered microbeads was also measured as 22.9 ns.