Sensing Fluoride Ion Research Articles

Bisthiocarbohydrazones as Colorimetric and “Turn on” Fluorescent Chemosensors for Selective Recognition of Fluoride

Bisthiocarbohydrazone derivatives of two heterocyclic ketones were designed and synthesized to selectively sense fluoride ion from a biologically competing solvent dimethylsulfoxide (DMSO). The selective recognition of fluoride is clearly visible to the naked eye with a distinct color change. The recognition mechanism has been investigated by UV–visible, fluorescence spectroscopy, and 1H NMR titration experiments. From the Benesi–Hidebrand equation and Job's plot, it was inferred that both compounds bind to fluoride with a 1:1 stoichiometry. 1H NMR titration data indicates deprotonation of the NH protons by fluoride as a prominent step in the recognition.

A new optical and electrochemical sensor for fluoride ion based on the functionalized boron–dipyrromethene dye with tetrathiafulvalene moiety

A new tetrathiafulvalene (TTF) derivative with the boron–dipyrromethene (BODIPY) moiety shows selectively optical and electrochemical sensing for fluoride ion. The mechanism of anion recognition has been investigated by 1H NMR titration and DFT calculations. The results show that the receptor with redox active TTF moiety and fluorescent BODIPY subunits may be useful as sensors for detecting and sensing fluoride ion.

Monitoring of diisopropyl fluorophosphate hydrolysis by fluoride-selective polymeric films using absorbance spectroscopy

In this study, a novel system for the detection and quantification of organofluorophosphonates (OFP) has been developed by using an optical sensing polymeric membrane to detect the fluoride ions produced upon OFP hydrolysis. Diisopropyl fluorophosphate (DFP), a structural analogue of type G chemical warfare agents such as Sarin (GB) and Soman (GD), is used as the surrogate target analyte. An optical sensing fluoride ion selective polymeric film was formulated from plasticized PVC containing aluminum(III) octaethyl porphyrin and ETH 7075 chromoionophore (Al[OEP]-ETH 7075). Selected formulations were used to detect the fluoride ions produced by the catalytic hydrolysis of DFP by the enzyme organophosphate hydrolase (OPH, EC 3.1.8.1). The changes in absorbance that corresponded to the deprotonated state of chromoionophore within the film results from simultaneous coextraction of fluoride and protons as DFP hydrolysis takes place in the solution phase in contact with the film. The developed sensing system demonstrates excellent sensitivity for concentrations as low as 0.1 μM DFP.

Ratiometric Fluorescence Sensing of Fluoride Ions by an Asymmetric Bidentate Receptor Containing a Boronic Acid and Imidazolium Group

AbstractThe synthesis of the first examples of anion receptors that utilize boron–fluoride interactions and (C–H)+···F–‐type ionic hydrogen‐bond interactions in the binding of F ions is reported herein. o‐, m‐, and p‐Phenylboronic acids were linked to naphthoimidazolium through a methylene group. On the basis of fluorescence and 19F NMR studies, we have confirmed that the addition of fluoride to a boron center occurs prior to the formation of (C–H)+···F–‐type ionic hydrogen bond with the imidazolium moiety. More importantly, these investigations have demonstrated that only the receptor bearing the ortho‐directed boron and imidazolium exhibits enhanced fluoride binding. The increased binding ability of the asymmetric bidentate receptor of ortho‐boronic acid and imidazolium towards F– enables it to sense fluoride ions in a 95:5 CH3CN/HEPES aqueous solution. The fluorescence responses to different anions were also explored; the ortho‐boron‐imidazolium receptor displayed ratiometric fluorescence changes and a high selectivity towards fluoride ions over other anions (Cl–, Br–, CH3CO2–, HSO4–, and H2PO4–).(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Electrode for sensing fluoride ion activity in solution.

Electrodes constructed from single-crystal sections of rare earth fluorides respond to fluoride ion activity over more than five orders of magnitude and show a high selectivity for fluoride over other common anions. These electrodes can be used for either direct measuremnent of fluoride ion activity or detection of the end point in titration.