Colorimetric detection of fluoride ions by anthraimidazoledione based sensors in the presence of Cu(ii) ions

Abstract

Anthraquinone based anion receptors have gained importance due to their colorimetric response on sensing a specific anion and the possibility of tuning this property by varying the conjugated moiety (the donor) to the diamine. In this work, we have synthesized and characterized four anthraimidazoledione compounds having 2,5-dihydroxy benzene, 4-(bis(2-chloroethyl)amino)benzene, imidazole and 4-methylthiazole moieties respectively (1-4). All of them were probed for their potential as anion sensors to study the effect of changes in the hydrogen bond donor-acceptor. The p-hydroquinone bound anthraimidazoledione (1) and thioimidazole bound anthraimidazoledione (4) were able to detect both F(-) and CN(-) in the presence of other anions Cl(-), Br(-), I(-), H2PO4(-), OAc(-), NO3(-)and ClO4(-). Both 1 and 4 could not differentiate F(-) from CN(-) and provided a similar response to both. The 1H NMR studies of 1 and 4 with F(-) showed the formation of [HF2](-) at 16.3 ppm and the 19F NMR showed a sharp peak at -145 ppm in both cases. However, although there may be NMR evidence of [HF2](-) formation F(-) may not be detected colorimetrically if the CT band remains almost unchanged, as found for 3. The results emphasize that the change of a hetero atom in the donor moiety of an anthraimidazoledione may render a large difference in sensitivity. In the case of 4 selective detection of F(-) was possible in the presence of 0.5 equivalent of Cu2+ with the exhibition of a distinct green colour with a Δλ shift of ca. 50 nm in contrast to CN(-) which showed orange colouration with a Δλ shift of only 15 nm. In the presence of Cu2+ the F(-) detection limit was 0.038(5) ppm (below the WHO specified level) at a receptor concentration of 25 μM.

Excited State Interaction of Ruthenium (II) Imidazole Phenanthroline Complex [Ru(bpy)2ipH]2+ with 1,4‐Benzoquinone: Simple Electron Transfer or Proton‐Coupled Electron Transfer?

“…1 H NMR spectra shown in Figure for [Ru(bpy) 2 ipH] 2+ with addition of varying proportions of 1,4‐benzoquinone display notable changes in spectrum particularly in the imidazole N−H broad singlet peak in the region of 9.1 ppm to 9.3 ppm with a downfield effect and also by the appearance of another new broad peak at around 14.95 ppm. The new peak at around 14.95 ppm is attributed as the outcome of the hydrogen bonding effect of N δ− …..H δ+ …..O δ− . While the same comparison is done with the [Ru(bpy) 3 ]Cl 2+ complex there is no evidence for this hydrogen bonding interactions (Figure S6).…”

“…The new peak at around 14.95 ppm is attributed as the outcome of the hydrogen bonding effect of N dÀ …..H d + …..O dÀ . [55] While the same comparison is done with the [Ru(bpy) 3 ]Cl 2 + complex there is no evidence for this hydrogen bonding interactions ( Figure S6). These results support the quenching mechanism involving the hydrogen bonding interaction of the complex [Ru(bpy) 2 ipH] 2 + with the 1,4-benzoquinone quencher.…”

A Novel Thiophene-Based Fluorescent Chemosensor for the Detection of Zn2+ and CN−: Imaging Applications in Live Cells and Zebrafish

“…Recently, anions have attracted notable interest, owing to their various roles in clinical, environmental, and biological applications [12][13][14]. In particular, cyanide has been extensively used in numerous territories like synthetic fiber, gold mining, resin industries, and metallurgy [15][16][17][18].…”

A π‐Conjugated Chromophore Dye and Its Functional Paper Strips for Visually On‐Site Sensing F− and Its Reaction Mechanism

“…For fluoride ion (F − ), the smallest size and highest charge density, any chronic deficiency of F − will lead to gastric and kidney disorder or osteoporosis, while excess F − would induce dental and skeletal fluorosis and other serious diseases including collagen breakdown, bone disorders and immune system disruption . Great efforts have been devoted for F − detection, such as chromatography, electrochemistry, photoluminescence, mass spectrometry,, fluorescent spectrophotometry and colorimetric spectrophotometry . For example, Bhosale, et al .…”