On–off–on fluorescent oligomer as a chemosensor for the detection of manganese(vii), sulfur(ii) and aldehydes based on the inner filter effect

Abstract

In this article, a sensitive and selective on–off–on fluorescence chemosensor, Tyloxapol (one kind of water soluble oligomer), was developed for the label-free detection of MnO₄⁻ ions in aqueous solution. From fluorescence experiments, it is demonstrated that Tyloxapol is a sensitive and selective fluorescence sensor for the detection of MnO₄⁻ directly in water over a wide range of anions including Cl⁻, Br⁻, I⁻, NO₃⁻, H₂PO₄⁻, HCO₃⁻, OH⁻, ClO₄⁻, Ac⁻, SO₄²⁻, HPO₄²⁻, CO₃²⁻, C₂O₄²⁻, S²⁻, SO₃²⁻, and Cr₂O₇²⁻. Moreover, the fluorescence intensity of Tyloxapol has shown a linear response to MnO₄⁻ in the concentration range of 0 to 120 μmol L⁻¹ with a detection limit of 0.392 μmol L⁻¹ MnO₄⁻. The interaction mechanism demonstrated that our on–off fluorescent oligomer probe for detecting Mn(VII) is based on the inner filter effect (IFE) because the absorption bands of Mn(VII) are fully covered by the excitation bands of Tyloxapol. Next, another turn-on sensing application of the Tyloxapol/MnO₄⁻ platform to probe S²⁻ against various other anions and aldehydes against various other organic pollutants were also established. It is expected that our strategy may offer a new approach for developing a simple, cost-effective, rapid and sensitive sensor for the detection of anions and aldehydes in environmental applications.