A simple ratiometric and colorimetric chemosensor for the selective detection of fluoride in DMSO buffered solution

Squaramide-based receptors in anion supramolecular chemistry: insights into anion binding, sensing, transport and extraction

Over the last 15 years, squaramide-based receptors have attracted the attention of supramolecular chemists working in the field of anion recognition. Herein, we highlight examples of squaramide-based receptors that are able to bind, sense, extract and transport anions.

A naphthoquinone based colorimetric probe for real-time naked eye detection of biologically important anions including cyanide ions in tap water: experimental and theoretical studies

A naphthoquinone based colorimetric sensor (N) bearing hydrazone receptors in aqueous media was developed and its recognition properties towards biologically important anions in DMSO–water mixture (9 : 1) were investigated using spectroscopic methods. The hydrazone based receptors showed selectivity towards anions (F⁻, OH⁻, CN⁻ and AcO⁻), through naked eye observable colour changes, from green to light blue (F⁻, CN⁻ and AcO⁻) and violet (OH⁻). The colour changes were concomitant with spectral changes. The sensor could also detect the presence of fluoride ions in commercially available toothpastes, through remarkable colour and spectral changes. In addition, test paper strips prepared from N were able to detect the presence of cyanide (KCN) and hydroxide (NaOH) in tap water. The study was complimented by density functional theory computations to have more insight in the interaction between N and the anions.

A naphthoquinone based colorimetric sensor (N) bearing hydrazone receptors in aqueous media was developed and its recognition properties towards biologically important anions in DMSO–water mixture (9 : 1) were investigated using spectroscopic methods.

Rapid detection of TNP based on a commercial fluorescent probe

A simple, rapid and low cost sensing method for the fluorescent detection of TNP in 100% aqueous media was successfully developed based on a commercial probe. Under the non-covalent interactions between TNP with probe, a ratiometric output signal was achieved, which can be applied in real samples test.

Boric-Acid-Functional Lanthanide Metal-Organic Frameworks for Selective Ratiometric Fluorescence Detection of Fluoride Ions

Here, we report that boric acid is used to tune the optical properties of lanthanide metal-organic frameworks (LMOFs) for dual-fluorescence emission and improves the selectivity of LMOFs for the determination of F^- ions. The LMOFs are prepared with 5-boronoisophthalic acid (5-bop) and Eu³⁺ ions as the precursors. Emission mechanism study indicates that 5-bop is excited with UV photons to produce its triplet state, which then excites Eu³⁺ ions for their red emission. This is the general story of the antenna effect, but electron-deficient boric acid decreases the energy transfer efficiency from the triplet state of 5-bop to Eu³⁺ ions, so dual emission from both 5-bop and Eu³⁺ ions is efficiently excited at the single excitation of 275 nm. Moreover, boric acid is used to identify fluoride specifically as a free accessible site. The ratiometric fluorescent detection of F^- ions is validated with the dual emission at single excitation. The LMOFs are very monodisperse, so the determination of aqueous F^- ions is easily achieved with high selectivity and a low detection limit (2 μM). For the first time, we reveal that rational selection of functional ligands can improve the sensing efficiency of LMOFs through tuning their optical property and enhancing the selectivity toward targets.

An easy prepared dual-channel chemosensor for selective and instant detection of fluoride based on double Schiff-base

A colorimetric and fluorescent dual-channel fluoride chemosensor N,N'-bis (4-diethylaminosalicylidene) hydrazine (sensor S) bearing two imine groups has been designed and synthesized. This structurally simple probe displays rapid response and high selectivity for fluoride over other common anions (Cl(-), Br(-), I(-), AcO(-), H2PO4(-), HSO4(-), ClO4(-), CN(-) and SCN(-)) in a highly polar aqueous DMSO solution. Mechanism studies suggested that the sensor firstly combined with F(-) through hydrogen bonds and then experienced the deprotonation process at higher concentrations of F(-) anion to the two Ar-OH groups. The detection limit was 5.78×10(-7)M of F(-), which points to the high detection sensitivity. Test strips based on sensor S were fabricated, which could act as a convenient and efficient F(-) test kit to detect F(-) for "in-the-field" measurement.