Abstract
AbstractHerein, we report the fluoride anion sensing properties of a commercially available and inexpensive organic compound, isatin, which is found to be a highly selective and sensitive sensor. In naked-eye experiments, by addition of fluoride anions, isatin shows a dramatic color change from pale yellow to violet at room temperature, while the addition of other anions,i.e.Cl−,$\mathrm{Cl}^-,$Br−,I−,ClO4−,H2PO4−andPF6−,$\mathrm{Br}^-,\mathrm I^-,\mathrm{ClO}_4^-,{\mathrm H}_2\mathrm{PO}_4^-\,\mathrm{and}\,\mathrm{PF}_6^-,$did not induce any colour change. Additionally, recognition and titration studies have also been done through UV/Vis spectroscopy. Isatin displayed a new absorption band at 533 nm after the addition of fluoride anions, which is presumably due to acid-base interaction between isatin and fluoride anions, while other anions did not trigger noticeable spectral changes. The detection limit was observed to be 0.367 ppm. DFT calculations were also performed to further explain the behavior of receptor 1 towards the Fˉ anion. Owing to high sensitivity and selectivity, isatin can be useful in the detection of biologically or environmentally important fluoride anions at very low concentration.
Highlights
In our everyday life, anions are valuable because they regulate and/or are responsible for numerous environmental and biological processes [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16]
As isatin 1 is a colored compound,its potential in anion recognition/sensing was first monitored by naked eye experiments
After obtaining the preliminary information of selectivity for fluoride anion with naked eye experiments (Figure 2), the chemosensor 1 was further evaluated by UV-Vis spectroscopy
Summary
Anions are valuable because they regulate and/or are responsible for numerous environmental and biological processes [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16]. Abstract: we report the fluoride anion sensing properties of a commercially available and inexpensive organic compound, isatin, which is found to be a highly selective and sensitive sensor. In naked-eye experiments, by addition of fluoride anions, isatin shows a dramatic color change from pale yellow to violet at room temperature, while the addition of other anions, i.e. Cl, Br, I, ClO4ˉ, H2PO4ˉ and PF6ˉ, did not induce any colour change.
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