A novel glycoconjugated N-acetylamino aldehyde hydrazone azo dye as chromogenic probe for cyanide detection in water

A new selective chemodosimeter probe of cyanide anions in aqueous media was developed by the introduction of a simple glyco-conjugated o-(carboxamido) aldehyde hydrazone into an azo dye as chemodosimeter that recognizes cyanide anions among other competing anions such as acetate, dihydrogen phosphate, fluoride through reversible covalent bonding. The sensing properties of the new materials were investigated in pure water and have demonstrated a very high selectivity toward the cyanide anions. The detection limit of the new chromogenic probe was measured to be 1.29 μM which is much lower than most recently reported chromogenic probes for cyanide determination.     

Biosourced 3-formyl chromenyl-azo dye as Michael acceptor type of chemodosimeter for cyanide in aqueous environment

A simple water-soluble aldehyde functionalized chromone 5 was utilized as a doubly activated Michael acceptor type of chemodosimeter for cyanide in water. The water solubility of the probe 5 is due to the incorporation of two glycerol units on the starting prepared chemodosimeter. This sensory system is able to selectively distinguish cyanide among fluoride and many other anions at micromolar concentrations and instantly detect cyanide in water at ambient temperatures with a detection limit down to 1.0 mM. Thus, the chemodosimeter 5 was applied to the quantitative determination of cyanide anion in drinking water sample (drinking water from commence).     

Fluorescent chemodosimeter for selective detection of cyanide in water

A coumarin-based fluorescent chemodosimeter with a salicylaldehyde functionality as a binding site has been developed for selective detection of cyanide anions over other anions in water at biological pH.     

Doubly activated coumarin as a colorimetric and fluorescent chemodosimeter for cyanide

A new α,β-unsaturated nitro group and coumarin conjugate-based fluorescent chemodosimeter 1 was developed for the selective detection of cyanide anions. The chemodosimeter has shown a selective and sensitive response to cyanide anions over other various anions through a nucleophilic aromatic substitution reaction of the cyanide to 1. When cyanide anions were added, the enhanced fluorescence intensity as well as the color changes of 1 was observed so that micromolar concentrations of cyanides were detectable by the naked eye.     

Coumarinyl aldehyde as a Michael acceptor type of colorimetric and fluorescent probe for cyanide in water

A simple aldehyde-functionalized coumarin (1) was utilized as a doubly activated Michael acceptor type of chemodosimeter for cyanide in water. The probe has shown a selective and sensitive response to the cyanide anion over other various anions through the Michael addition reaction of the cyanide to 1. When cyanide anions were added, the prominent color changes as well as fluorescence changes of 1 were observed so that millimolar concentrations of cyanides were detectable by the naked eye.     

Acridinium salt based fluorescent and colorimetric chemosensor for the detection of cyanide in water

A new, selective chemosensor has been developed to detect cyanide in water at micromolar concentrations. The acridinium salt used in this sensor system is prepared in a single step from an acridine orange base. Detection is based on the irreversible, 1:1 stoichiometric, nucleophilic addition of cyanide to the 9-position of the acridinium ion. This process induces a large decrease in fluorescence intensity and a marked color change. The selectivity of the system in aqueous media for CN- over other anions is remarkably high. Also, the sensitivity of both the fluorescence- and colorimetric-based assay is below the 1.9 microM suggested by the World Health Organization (WHO) as the maximum allowable cyanide concentration in drinking water. Thus, the chemodosimeter should be applicable as a practical system for the monitoring of CN- concentrations in aqueous samples. [structure: see text]     

Coumarin-Cu(II) ensemble-based cyanide sensing chemodosimeter

An "ensemble"-based chemodosimeter 1-Cu(II) for cyanide detection is reported. 1-Cu(II) can recognize a cyanide ion over other anionic species to show a marked fluorescence enhancement under aqueous conditions. "Off-on" fluorescence change of 1-Cu(II) is proceeded by addition of cyanide, which induces decomplexation of the Cu(II) ion from nonfluorescent 1 followed by hydrolytic cleavage of the resulted Schiff base to give a strongly fluorescent coumarinaldehyde (2). The selective detection of cyanide with 1-Cu(II) for biological application was also performed in HepG2 cells.     

Sensing cyanide ion via fluorescent change and its application to the microfluidic system

We introduce a cyanide selective microfluidic platform, in which fluorescent chemodosimeter 1 displayed a selective green fluorescence upon the addition of cyanide. Our system was examined in aqueous solution, and the ‘OFF-ON’ type emission change can be monitored over 500 nm. In addition, colorimetric change was also observed upon the addition of cyanide. The practical use of the probe was demonstrated by its application to the detection of cyanide in the living cells.     

A reaction-based chromogenic and fluorescent chemodosimeter for fluoride anions

An innovative trihexylsilylacetylene-containing BODIPY dye was designed and proved to be a highly selective, sensitive, and fast chromogenic and fluorescent chemodosimeter for fluorides.     

A selective, sensitive, and chromogenic chemodosimeter for cyanide based on the 1,1'-binaphthyl scaffold

A highly selective chemodosimeter 1 for cyanide based on the 1,1'-binaphthyl skeleton is described which demonstrated significant visual change and a low limit of detection. Interestingly, a reversible process triggered successively by CN(-) and Au(3+) is also observed and determined by fluorescence, UV-vis spectra, (1)H NMR titration, and ESI-MS.     

A lab-on-a-molecule for anions in aqueous solution: using Kolbe electrolysis and radical methylation at iridium for sensing

Iridium complex [(pq)(2)IrCl](2) (1) is established as a quantitatively operating lab-on-a-molecule in aqueous media at physiological pH. Acting as a chemodosimeter, 1 uses two channels, PL and ECL, for the detection of cyanide and acetate, with the former undergoing nucleophilic attack and the latter Kolbe electrolysis and radical-metal combination.     

Cyanine dye-based chromofluorescent probe for highly sensitive and selective detection of cyanide in water

Cyanine dye Cy5 was used to be a probe for highly selective detection of trace cyanide in water by using a convenient two-phase strategy. The detection limit of both the fluorescent and colorimetric assay for cyanide is below 1.9 μM, the maximal allowance level for drinking water set by the World Health Organization.     

Highly selective sensing of cyanide by a benzochromene-based ratiometric fluorescence probe

Enone-functionalized benzochromene chemodosimeter (1) was prepared through the Baylis-Hillman condensation reaction and was utilized as a ratiometric fluorescence probe for cyanide anions in aqueous buffer. The probe has shown a selective and sensitive response to cyanides over other various anions through the Michael addition and a subsequent [1,3]-sigmatropic rearrangement reaction. When cyanide anions were added, a prominent ratiometric fluorescence change of 1 was observed thus allowing to detect the micromolar concentration of cyanides by the naked eye.     

Simple Michael acceptor type coumarin derived turn-on fluorescence probes to detect cyanide in pure water

The present article describes design and synthesis of coumarin derived chemical reaction based chemodosimeter to recognize cyanide in aqueous medium. The Michael acceptor type coumarin derived probes 3 and 4 upon interaction with cyanide undergo Michael type nucleophilic addition reaction to form adducts in which fluorescence intensity was significantly enhanced, ‘turn-on’ by the change in intramolecular charge transfer (ICT) mechanism. The nonfluorescent color of solutions changed to a naked-eye sensitive fluorescent blue (switched-on). Job’s plot analysis revealed a 1:1 stoichiometry for the interaction between the probe and cyanide anion with a high detection limit.     

Tracking of mercury ions in living cells with a fluorescent chemodosimeter under single- or two-photon excitation

Tracking of Hg²⁺ in solutions as well as in living cells was conducted with a fluorescent chemodosimeter by measuring the spectral shift of its fluorescence under single- or two-photon excitation. The spectral hypsochromic shifts of this chemodosimeter when reacting with Hg²⁺ were found to be about 50 nm in acetonitrile/water solutions and 32 nm in Euglena gracilis 277 living cells. This chemodosimeter shows high sensitivity and selectivity, and is not influenced by the pH values. It can signal Hg²⁺ in solutions down to the ppb range under either single-photon excitation (SPE) at 405 nm or two-photon excitation (TPE) at 800 nm. However, with low cellular chemodosimeter concentrations, the SPE spectra were disturbed by the auto-fluorescence from the native fluorophore in the cell, while the TPE spectra were still of high quality since the two-photon absorption cross section of this chemodosimeter is much larger than that of the native fluorophores in the cell.     

A novel cyanide chemodosimeter based on trifluoroacetamide benzhydrol-2 as binding motif: importance of substituent positioning on intra-molecular charge transfer

The nucleophilic nature of cyanide is used to develop a simple, sensitive, and highly effective sensor. Azo dye 6a based on 2-(trifluoroacetamide) benzhydrol-2 (2-TFAB) as anions receptor, presents a new way to build molecular color sensors for cyanide in water. The 2-TFAB moiety of the dye 6a is used as receptor group for cyanides and linked directly by dominant reversible covalent bonding over hydrogen bonding, confirmed by the inactivity of the derivative 6b toward cyanides.     

A selective quinoline-derived fluorescent chemodosimeter to detect cyanide in aqueous medium

A simple quinoline derived probe 3 has been described. Probe 3 having aldehyde function upon interaction with cyanide undergo nucleophilic addition reaction to form cyanohydrin derivative 4 in which fluorescence intensity enhances significantly, ‘turn-on’ by photoinduced electron transfer (PET) OFF–ON mechanism. The color of probe solution switched-on to fluorescent blue which is visible to the naked-eye. Job’s plot analysis revealed a 1:1 stoichiometry for an interaction between 3 and cyanide along with detection limit 0.058 μM (1.5 ppb). The mode of interaction to detect cyanide in aqueous medium through a reaction based chemodosimeter approach has been confirmed by NMR, mass, FTIR, and DFT data analysis.     

Allosteric Indicator Displacement Enzyme Assay for a Cyanogenic Glycoside

Indicator displacement assays (IDAs) represent an elegant approach in supramolecular analytical chemistry. Herein, we report a chemical biosensor for the selective detection of the cyanogenic glycoside amygdalin in aqueous solution. The hybrid sensor consists of the enzyme β‐glucosidase and a boronic acid appended viologen together with a fluorescent reporter dye. β‐Glucosidase degrades the cyanogenic glycoside amygdalin into hydrogen cyanide, glucose, and benzaldehyde. Only the released cyanide binds at the allosteric site of the receptor (boronic acid) thereby inducing changes in the affinity of a formerly bound fluorescent indicator dye at the other side of the receptor. Thus, the sensing probe performs as allosteric indicator displacement assay (AIDA) for cyanide in water. Interference studies with inorganic anions and glucose revealed that cyanide is solely responsible for the change in the fluorescent signal. DFT calculations on a model compound revealed a 1:1 binding ratio of the boronic acid and cyanide ion. The fluorescent enzyme assay for β‐glucosidase uses amygdalin as natural substrate and allows measuring Michaelis–Menten kinetics in microtiter plates. The allosteric indicator displacement assay (AIDA) probe can also be used to detect cyanide traces in commercial amygdalin samples.     

A mesoporous 3D hybrid material with dual functionality for Hg2+ detection and adsorption

Dual-function hybrid material U1 was designed for simultaneous chromofluorogenic detection and removal of Hg(2+) in an aqueous environment. Mesoporous material UVM-7 (MCM41 type) with homogeneously distributed pores of about 2-3 nm in size, a large specific surface area exceeding 1000 m(2) g(-1), and nanoscale particles was used as an inorganic support. The mesoporous solid is decorated with thiol groups that were treated with squaraine dye III to give a 2,4-bis(4-dialkylaminophenyl)-3-hydroxy-4-alkylsulfanylcyclobut-2-enone (APC) derivative that is covalently anchored to the inorganic silica matrix. The solid was characterised by various techniques including X-ray diffraction, transmission electron microscopy, Raman spectroscopy, and nitrogen adsorption. This hybrid solid is the chemodosimeter for Hg(2+) detection. Hg(2+) reacts with the APC fragment in U1 with release of the squaraine dye into the solution, which turns deep blue and fluoresces strongly. Naked-eye Hg(2+) detection is thus accomplished in an easy-to-use procedure. In contrast, U1 remains silent in the presence of other thiophilic transition metal ions, alkali and alkaline earth metal ions, or anions ubiquitously present in water such as chloride, carbonate, sulfate, and phosphate. Material U1 acts not only as chemodosimeter that signals the presence of Hg(2+) down to parts-per-billion concentrations, but at the same time is also an excellent adsorbent for the removal of mercury cations from aqueous solutions. The amount of adsorbed mercury ranges from 0.7 to 1.7 mmol g(-1), depending on the degree of functionalisation. In addition, hybrid material U1 can be regenerated for both sensing and removal purposes. As far as we know, U1 is the first example of a promising new class of polyfunctional hybrid supports that can be used as both remediation and alarm systems by selective signalling and removal of target species of environmental importance. Model compounds based on silica gel (G1), fumed silica (F1), and micrometre-sized MCM-41 scaffolds (M1) were also prepared and studied for comparative purposes.     

Studies of solvation in homogeneous and heterogeneous media by electronic spectroscopic method

Solvation characteristics in homogenous (pure and mixed binary solvents) and heterogeneous media (aqueous micelles, beta- and gamma-cyclodextrine solutions) have been studied by monitoring the emission characteristics of a newly synthesised dye. The longest wavelength absorption and emission band of the dye arise due to transition between S(0) and S(1) state. The maximum energy of electronic transition involving intramolecular charge transfer is found to be dependent on both the hydrogen-bond donating ability and the polarity-polarisability in pure solvent. The dipole moment in the S(1) state, as determined by solvatochromic procedure, agrees well with the value obtained by theoretical calculation at the AM1 level. Preferential solvation of the dye by alcohols has been found to occur in ethanol+water, propan-1-ol+water, propan-2-ol+water binary mixtures. In aqueous micellar media the dye molecule is located at the water-micelle interface. The binding constant for the dye-micelle interaction has also been determined. The results have been compared with those for a structurally related symmetrical ketocyanine dye.