Abstract

Kanokorn Wechakorn*¹, Pairsunan Chanpanich², Pimfa Kamkalong² and Suranan Anantachisilp²

DOI : http://dx.doi.org/10.13005/ojc/350318

Rhodamine-triazole sensor functionalized Fe₃O₄@SiO₂ nanoparticles were developed for the detection of heavy metal ions, namely Cu²⁺, Ni²⁺, Hg²⁺, Co²⁺, Fe³⁺, and Pb²⁺. Rhodamine conjugated with a triazole moiety (RBT) was utilized as the metal ion binding site. The RBT-Fe₃O₄@SiO₂ nanoparticles were fully characterized by XRD, FTIR, TGA, SEM and TEM techniques. Additionally, RBT-functionalized Fe₃O₄@SiO₂ nanoparticles can be separated from the aqueous phase by application of an external magnet, leading to clear naked-eye observation of the color changes and fluorescence enhancement. From UV-Vis absorption spectra, aqueous solutions of RBT-Fe₃O₄@SiO₂ in the presence of heavy metal ions show an absorption peak at 554 nm. Fluorescence titration experiments reveal that the intensity of the fluorescence emission band at 574 nm is linearly dependent on Cu²⁺ concentration, over a 100-800 µM range. Furthermore, complexation of Cu²⁺ by RBT-Fe₃O₄@SiO₂ nanoparticles can induce ring-opening of the rhodamine spirolactam ring followed by hydrolysis, confirmed by mass spectrometry.

Fluorescent Sensor; Heavy Metal Ions; Magnetic Nanoparticles; Rhodamine; Triazole

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