Furo[3,2-c]coumarin-derived Fe3+ Selective Fluorescence Sensor: Synthesis, Fluorescence Study and Application to Water Analysis

Sarih, Norfatirah Muhamad, Ciupa, Alexander, Moss, Stephen, Myers, Peter ORCID: 0000-0002-5842-3511, Slater, Anna Grace ORCID: 0000-0002-1435-4331, Abdullah, Zanariah, Tajuddin, Hairul Anuar and Maher, Simon
(2020) Furo[3,2-c]coumarin-derived Fe3+ Selective Fluorescence Sensor: Synthesis, Fluorescence Study and Application to Water Analysis. Scientific Reports, 10 (1). 7421-.

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Furocoumarin (furo[3,2-c]coumarin) derivatives have been synthesized from single step, high yielding (82-92%) chemistry involving a 4-hydroxycoumarin 4 + 1 cycloaddition reaction. They are characterized by FTIR, <sup>1</sup>H-NMR, and, for the first time, a comprehensive UV-Vis and fluorescence spectroscopy study has been carried out to determine if these compounds can serve as useful sensors. Based on the fluorescence data, the most promising furocoumarin derivative (2-(cyclohexylamino)-3-phenyl-4H-furo[3,2-c]chromen-4-one, FH), exhibits strong fluorescence (ФF = 0.48) with long fluorescence lifetime (5.6 ns) and large Stokes' shift, suggesting FH could be used as a novel fluorescent chemosensor. FH exhibits a highly selective, sensitive and instant turn-off fluorescence response to Fe<sup>3+</sup> over other metal ions which was attributed to a charge transfer mechanism. Selectivity was demonstrated against 13 other competing metal ions (Na<sup>+</sup>, K<sup>+</sup>, Mg<sup>2+</sup>, Ca<sup>2+</sup>, Mn<sup>2+</sup>, Fe<sup>2+</sup>, Al<sup>3+</sup>, Ni<sup>2+</sup>, Cu<sup>2+</sup>, Zn<sup>2+</sup>, Co<sup>2+</sup>, Pb<sup>2+</sup> and Ru<sup>3+</sup>) and aqueous compatibility was demonstrated in 10% MeOH-H<sub>2</sub>O solution. The FH sensor coordinates Fe<sup>3+</sup> in a 1:2 stoichiometry with a binding constant, K<sub>a</sub> = 5.25 × 10<sup>3</sup> M<sup>-1</sup>. This novel sensor has a limit of detection of 1.93 µM, below that of the US environmental protection agency guidelines (5.37 µM), with a linear dynamic range of ~28 (~2-30 µM) and an R<sup>2</sup> value of 0.9975. As an exemplar application we demonstrate the potential of this sensor for the rapid measurement of Fe<sup>3+</sup> in mineral and tap water samples demonstrating the real-world application of FH as a "turn off" fluorescence sensor.

Item Type: Article
Depositing User: Symplectic Admin
Date Deposited: 06 May 2020 09:47
Last Modified: 18 Jan 2023 23:52
DOI: 10.1038/s41598-020-63262-7
Open Access URL: https://doi.org/10.1038/s41598-020-63262-7
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URI: https://livrepository.liverpool.ac.uk/id/eprint/3086130