Cyanide Ion In Aqueous Solution Research Articles

A reaction based carbazole-indolium conjugate probe for the selective detection of environmentally toxic ions.

A nucleophilic addition based chemodosimeter was designed and synthesized with a carbazole donor and an indole acceptor. The addition of a cyanide ion to an electron-deficient indole moiety disrupts the acceptor-donor relationship, resulting in noticeable color shifts and spectrum differences in both the absorption and emission profiles. The design has a D-π-A molecular arrangement. Selectivity was investigated in 90% aqueous DMSO solution of probe CI with various anions such as SCN-, PF6-, NO3-, N3-, I-, HSO4-, CN-, H2PO4-, F-, HS-, ClO4-, Cl-, Br-, and AcO-. An intermolecular charge transfer (ICT) band at 506 nm in the UV-visible spectra vanished and the intensity of emission was quenched at 624 nm upon the addition of CN- ions. These outcomes demonstrate the effective nucleophilic addition of cyanide ions to the electron-deficient indole moiety of the probe, resulting in the formation of a new adduct in which the ICT transition is interrupted when π conjugation is blocked. The Job plot, 1H NMR spectroscopy, and HRMS analysis confirmed the formation of a new product. An outstanding response was shown by paper test strips made using probe molecules for the easy detection of cyanide ions in aqueous solutions. Besides, the probe selectively senses cyanide ions in different water samples.

Rational design of aza-BODIPY derived near-infrared fluorescent probe for CN− in aqueous solutions

The lethal toxicity of cyanide ions has inspired the development of fluorescent probes for their recognition, but fluorescent probes that can selectively bind cyanide ions in aqueous solution have been a challenge. In this paper, the electron-donor/withdrawing groups were introduced to aza-BODIPY fluorophore to discover the optical properties and tune the addition reaction with CN−. The push-pull electron effect of the corresponding substituents in aza-BODIPY makes the spectral shifts, molar extinction coefficients and fluorescence quantum yields remarkably different. The introduction of the electron-withdrawing group (–CF3) to aza-BODIPY (CF3-BDP) resulted in the electron-deficient property of the CN double bond, and the ability of nucleophilic addition of CN− to CF3-BDP was enhanced in aqueous solutions. Due to the collapse of the conjugated structure after the addition, the fluorescence of CF3-BDP was rapidly quenched to realize the highly sensitive response to CN−. According to DFT calculation, the reaction site of controversial mechanism was verified to the CN band in the pyrrole of aza-BODIPY. Furthermore, CF3-BDP was proved to have the ability to detect cyanide in biological system.

Colorimetric and fluorescent probe based on coumarin for sequential sensing of mercury (II) and cyanide ions in aqueous solutions

A novel coumarin-thiol chemosensor L for sequential colorimetric and fluorescent detection of mercury (II) and cyanide ions in aqueous solution has been designed and prepared. The probe L exhibits high selectivity and sensitivity towards mercury (II) cations, and forms the complex L/Hg2+ which exhibits red-shift and fluorescence quenching. In turn, the complex L/Hg2+ shows high selectivity for cyanide anions, which release the L probe and explain the blue shift and restoration of the original fluorescence. A test paper was also developed by fixing the probe L on the surface of a filter paper. This test paper allows the simultaneous detection of mercury (II) and cyanide ions in pure water without the need for additional equipment.

A highly selective optical sensor for the detection of cyanide ions in aqueous solution and living cells

A fluorogenic naphthalene based receptor (NFS) has been successfully generated by preparation from 3-amino-2-naphthol and 2-hydroxy-1-naphthaldehyde, it was then characterized. Optical and colorimetric properties of the receptor (NFS) in terms of cyanide (CN-) ions were investigated by several methods including naked-eye detection, UV–vis spectrophotometry and fluorescence spectroscopy. A visual color change from yellow to orangish-pink was observed upon interaction of the receptor with cyanide (CN-) ions in solution, while no color change appeared upon addition of the other anions tested. The detection limit of NFS was calculated as 0.21 µM without any interaction with other anions tested which is lower than that described by the World Health Organization for CN– ions in drinking water. It can be concluded that the receptor (NFS) was sensitive and rapid enough for the detection of CN- ions in solutions. The interaction between the receptor and CN– ions was also investigated by 1H NMR titration, MALDI-Tof mass spectrometry, and FTIR-AR spectroscopy. NFS was also applied to the bio-imaging of human epithelial cell line (HEK 293) and the cell imaging studies demonstrated that the receptor was capable of detecting cyanide ions in living cells.

Visually detecting cyanide ion in aqueous solution sensitively and selectively using a merocyanine salt with the help of a smartphone

Naked eye visual detection of cyanide ion (CN−) was explored in an aqueous-organic medium (1:1) by using a merocyanine (MC) based probe. The structure validation of the probe was accomplished using spectroscopic techniques. Evaluation of the probe in Tris buffer at pH 7.6 revealed yellow color as a result of its interaction with cyanide ion, which was originally pink in color. Inspection of UV–vis data revealed reduced intensities of absorption bands at 390 nm and 525 nm on adding cyanide ions in probe solution. An abrupt color change visible with the unaided eyes due to the interaction of the probe with cyanide ion proved advantageous in the development of a digital colorimetry-based analytical protocol for evaluation of CN− ions existence in solution. A change in chemical shift of protons in the 1H NMR spectrum implied interaction between the hydroxyl group proton of the probe and CN− ion that results in the displacement of the p-toluenesulfonate group by incoming CN− ion. Dynamic light scattering (DLS) studies also affirmed the aggregation of the probe and in its mixture with CN− ion. The calculation of parameters using density functional theory (DFT) with M06–2X functional further signaled the formation of a complex through the H-bond. Excitation parameters calculated using CAM-B3LYP studies also furnished results in support of experimental data.

Copper nanoclusters with/without salicylaldehyde-modulation for multifunctional detection of mercury, cobalt, nitrite and cyanide ions in aqueous solution and bioimaging

The sensitive determination of multiple heavy metal ions and toxic anions is important in biological and environmental fields. Here we report a facile strategy to construct a multifunctional chemosensor for the detection of Hg2+, Co2+, and CN− in aqueous solution based on the fluorescent copper nanoclusters (Cu NCs). It was interesting to find that salicylaldehyde (SA) could effectively modulate the fluorescence property and sensing behavior of Cu NCs. In the absence of SA, Cu NCs showed ‘on-off’ fluorescence responses at the addition of Hg2+ and under different quenching mechanisms. Upon the presence of SA, Cu NCs exhibited a strong intramolecular charge transfer emission at 500 nm, accompanied by the decrease of the initial fluorescence of Cu NCs at 430 nm. This fluorescence on-state of Cu NC–SA at 500 nm was found to be exclusively turned off by Co2+ and enhanced by CN−. Spectroscopy results combined with thermodynamic analysis provided sufficient information to deduce the sensing mechanisms. Finally, the Cu NCs showed high biocompatibility and were able to be used for fluorescence bioimaging in living cells. This study provided a novel and simple strategy to construct the multifunctional chemosensors for bioanalytical applications.

Development of simple imine based probe for selective fluorescent cyanide sensing with red-emission in solid and solution phases

In the present work, an easy to make imine based receptor (3,3′(((5-(tert-butyl)-2-hydroxy-1,3-phenylene)bis(methanylylidene))bis(azanylylidene))bis(2-aminomaleonitrile)) (CNA) has been synthesized in good yield and characterized by spectral methods. CNA showed rapid, selective and sensitive naked-eye dual channel response (colorimetric and fluorogenic) towards cyanide ion. The receptor exhibited instantaneous colour change upon addition of cyanide ion based on deprotonation of phenolic –OH moiety in neat DMSO, 30% aq. DMSO and solid media. Interestingly, CNA showed red-emission (640 nm < λem < 677 nm) upon treatment with cyanide ion in all these media. Limit of detection of CNA for cyanide ion was determined to be 0.5 μM, which is much lower than the permissible limit of cyanide in drinking water as recommended by the World Health Organization. The fabricated cotton swabs and test strips demonstrated excellent selectivity towards cyanide ion in aqueous solution. Further, CNA is suitable for dual channel detection of cyanide ion in food materials. Furthermore, the observable colour change of the probe upon binding with cyanide ion has successfully been integrated with a smartphone Colour Picker app to estimate cyanide ions.

Triphenylamine-thiophene dyad as a Chemodosimeter for specific recognition of cyanide ions in aqueous solutions

Triphenyl amine-thiophene conjugated with benzothialzole derivative TP-1 have been synthesized and explored as new colorimetric and turn-on fluorescent Chemodosimeter for cyanide anions. The probe TP-1 showing a discrete visible color change from dark yellow to colorless and subsequently the fluorescence intensity gets increased after addition of the cyanide anions, it's very selective towards cyanide ions. The probe is showing the increase in fluorescence with cyanide ions in the linear range 1–100 μM. The limit of detection for cyanide ions by the probe TP-1 was found to be 4.24 × 10−8 M. The observed absorption, fluorescence changes was further supported by density functional theory calculations and the internal charge transfer mechanism is takes place while addition of cyanide ions. Further low cytotoxic behavior of TP-1 makes the probe feasible for live cell detection of cyanide ions.

Chemical sensor using metal-organic complex: Preparation, characterization and application for highly selective detection of cyanide ions in mixed aqueous-organic media

In this study, a novel metal-organic hybrid material (MO1) was designed and synthesized for the detection of CN− ions. The spectral analyses by FT-IR, 1H NMR, 13C NMR, CHN and TGA satisfactorily confirmed the structure of MO1. The sensor MO1 was applied as colorimetric probe for sensing of cyanide ions in aqueous solutions of dimethyl sulfoxide. MO1 with electron withdrawing group at organic ligand showed high selectivity for detection of cyanide over other interfering anions. Interaction of MO1 with cyanide provides obvious colorimetric change from red to violet, enabling easy detect with the naked eye. In addition, the sensing details were evaluated using UV–vis spectroscopy. Furthermore, the detection limit of chemosensor toward CN‾ ions was found to be 5.52 μM. Moreover, probe MO1 can be used for selective sensing of cyanide based on the obvious color changes in real samples.

Multispectroscopic and theoretical studies on rapid, selective and sensitive visual sensing of cyanide ion in aqueous solution by receptors possessing varying HBD property

Three new benzoquinone–imidazole ensembles possessing varying number (0, 1 and 2) of electron-withdrawing bromo substituents on the quinone ring have been designed, synthesized, characterized and employed as receptors in cyanide sensing. These receptors colorimetrically sense cyanide ion selectively and sensitively in aq. 4-(2-hydroxyethyl)-1-piperazineethanesulphonic acid (HEPES) buffer–acetonitrile (ACN) (8:2 v/v) medium with striking colour change that can easily be seen visually. Fluorescence spectral studies revealed that the receptors form strong complex at 1:1 stoichiometry with cyanide ion. The binding constants for the complexes were found to be in the order of 105–107 M−1 and increase with increasing number of bromo substituents on the quinone ring. The detection limit of cyanide by these receptors lay in the range of 10−8 M. The effects of the number of bromo substituents on the absorption maximum, reduction potential and H-bond donor (HBD) property of imidazole N–H are discussed. The results of spectral studies corroborate well with those of electrochemical and theoretical studies. An easy-to-use test strip was prepared to test cyanide in aqueous solution of sodium cyanide prepared using deep-well water.

A simple benzildihydrazone derived colorimetric and fluorescent ‘on–off-on’ sensor for sequential detection of copper(II) and cyanide ions in aqueous solution

Herein, we have developed a simple, environment friendly fluorescent turn-off and colorimetric sensor for the rapid detection of Cu2+ ions in aqueous solution by using organic Schiff base ligand benzildihydrazone-N,N'-bis(2-hydroxy-4-diethylamino-1-formylbenzene) (L). Binding interaction between L and various metal ions was established by UV–vis and fluorescent measurements showing favourable coordination towards Cu2+ and almost no interference with the other metal ions, i.e., Na+, Ba2+, Fe3+, Co2+, Ni2+, Zn2+, Cd2+, Ca2+, Hg2+, Pb2+,Cr3+, Ag+ and Al3+. L exhibited binding-induced colour change from yellow to light red. The obtained L-Cu2+ complex could be used as a new cascade sensor for detecting cyanide anion (CN−). The corresponding detection limits were found to be 7.3×10−10M for Cu2+ (lowest ever known in the family of fluorescent colorimetric Schiff base chemo-sensor) and 1.5×10−7M for CN−. To further assess the analytical performance of this sensing system, the concentrations of Cu2+ and CN−1 ions were determined in real water samples and simulated urine sample.

Nanophotosensitive drugs for light-based cancer therapy: what does the future hold?

Nanophotosensitive drugs for light-based cancer therapy: what does the future hold?

Detection of cyanide ions in aqueous solutions using cost effective colorimetric sensor

Cyanide (CN̄) is one of the most toxic material to the human and environment. It is very important to develop the diagnostic tools for the detection of CN̄ ions. Moreover, detection of the ions in an aqueous medium is a challenging task as water molecules interfere with the sensing mechanism. In this context, we prepared chemical sensor, S1, having anthraquinone as a signaling unit and thiourea as a binding site. This sensor exhibited distinct visual color and spectral changes in response to CN̄ ion over other testing anions in 50% aq. DMSO solution. However, in 20% aq. DMSO solution, S1 exhibited obvious spectral and color changes in response to CN̄, fluoride (F̄), acetate (Ac̄) and benzoate (Bz̄). Another sensor, S2, having a same signaling unit with that of S1, but a different binding site of urea group. In contrast to S1, S2 exhibited obvious spectral and color changes to F̄ in 2.5% aq. DMSO solution. NMR titration results suggested that the spectral and colorimetric responses were due to the formation of host-guest complex and deprotonation events. Finally, economically viable paper-based colorimetric “test stripes” of S1 were fabricated to detect the CN̄ ions in 100% aqueous solution.

N and F Codoped TiO2 Thin Films on Stainless Steel for Photoelectrocatalytic Removal of Cyanide Ions in Aqueous Solutions

N-F codoped TiO2 films were immobilized on stainless steel sheets through a combined approach involving a dip-coating technique and a hydrothermal treatment, followed by calcination at 400°C in the presence of air. Photocatalyst characterization was conducted using XRD, Raman and UV-VIS spectroscopy as well as SEM. The films were tested in a three-electrode cell for the photoelectrocatalytic degradation of CN-containing compounds. The results showed that the increase in the degradation rate of CN-containing compounds is both influenced by a synergistic effect of the doping agents and strongly dependent on the concentration of CN-containing compounds in the solution. Nitrogen contributed to the enhanced photoactivity under visible light due to the generation of localized states within the band gap of TiO2, whereas the presence of fluoride improved the superficial properties of the film, which resulted in higher amounts of CN-containing compounds that were degraded by direct charge transfer through the photogenerated holes.

A reaction based colorimetric chemosensor for the detection of cyanide ion in aqueous solution

A conjugated naphthoquinone-benzothiazole (R) system was developed and characterized and its cyanide sensing properties were monitored in 80% aqueous DMF solution. Cyanide ions react with the receptor through a nucleophilic addition reaction, resulting in immediate color change that can be viewed and monitored colorimetrically and fluorimerically. Optical properties of R were not affected by the addition of other common anions in the presence and absence of cyanide ions. A test strip based on R was fabricated and could act as a convenient test kit to detect cyanide ions. Thus, the receptor can be used as an effective probe to detect cyanide ions in aqueous solution.

An interesting spectroscopic method for chromofluorogenic detection of cyanide ion in aqueous solution: Disruption of intramolecular charge transfer (ICT)

5-[4-(dimethylamino)benzylidene) pyrimidine-2,4,6(1H,3H,5H)]-trione (DMP-3H), the receptor was synthesized which played a chemosensor role for cyanide ion (CN−) in aqueous solution with colorimetric and fluorescence turn-off responses. Upon addition of CN− ion into the solution containing the receptor, a color change visible to the naked eye was observed from yellow to colourless and also, the fluorescence of the solution was immediately quenched. Moreover, DMP-3H exhibited a selective response to cyanide ion over many other anions such as F−, Cl−, Br−, I−, SO $_{\mathrm {3}}^{\mathrm {2-}}$ , OCN−, ClO $_{\mathrm {3}}^{\mathrm {-}}$ , CO $_{\mathrm {3}}^{\mathrm {2-}}$ , IO $_{\mathrm {3}}^{\mathrm {-}}$ , N $_{\mathrm {3}}^{\mathrm {-}}$ , C $_{\mathrm {2}}\textit {O}_{\mathrm {4}}^{\mathrm {2-}}$ and SCN−. The detection limit toward CN− was 8.1 × 10 −7 mol.L−1, which is satisfactory enough for monitoring CN− levels in physiological and environmental systems.

Hexagonal cadmium oxide nanodisks: Efficient scaffold for cyanide ion sensing and photo-catalytic applications

Herein, we report the large-scale low-temperature aqueous solution based synthesis of hexagonal-shaped cadmium oxide (CdO) nanodisks. The synthesized nanodisks were characterized in detail to investigate the morphological, structural, optical and compositional properties using various analytical tools. The detailed characterizations revealed that the synthesized CdO nanodisks are grown in high-density, possessing well-crystallinity with cubic crystal phase and exhibiting good optical properties. Further, the prepared CdO nanodisks were used as efficient scaffold for cyanide ion sensor and photocatalyst applications. A luminescent sensor for the determination of cyanide ion in aqueous solution was fabricated based on synthesized CdO nanodisks. The fabricated luminescent sensor exhibited an extremely low detection limit (~1.40μmolL−1) towards cyanide ion which is significantly lower than the maximum permitted value of cyanide ion by United States Environmental Protection Agency (EPA) for drinking water (7.69μmolL−1). The interference studies of the fabricated sensor also demonstrate excellent selectivity towards cyanide ions compared to other coexisting ions. As a photocatalyst, the synthesized CdO nanodisks exhibited high photodegradation (~99.7%) of toxic methyl orange dye just in 90min using 0.25g of CdO nanodisks.

A highly sensitive and selective “turn-on” fluorescence sensor for rapid detection of cyanide ions in aqueous solution

A simple and easily synthesised colorimetric and fluorescent cyanide probe bearing salicylaldehyde hydrazone functionality has been synthesised and characterised. This probe displays rapid response, highly selective and sensitive recognition for cyanide over other competitive anions (F−, Cl−, Br−, I−, AcO−, , , , and SCN−) in the aqueous solution. Furthermore, the detection limit of the fluorescent assay for cyanide is 1.96 × 10−8 M, which is much lower than the maximum value of cyanide (1.9 μM) permitted by the World Health Organization in drinking water. In addition, the sensor exhibited both a colour change from colourless to yellow and fluorescence enhancement upon addition to CN− in DMSO/H2O (6:4,v/v). Thus, the present probe should be applicable as a practical system for the detection of highly toxic and deadly cyanide ion in aqueous samples.

A diquinone–imidazole ensemble for selective colorimetric sensing of cyanide in aqueous medium via anion induced NIR absorption

The receptor selectively and sensitively senses cyanide ions in aqueous solution with a striking colour changeviaanion induced NIR absorption (913 nm).

A simple Schiff base as ‘naked eye’ and fluorescent ‘on–off’ sensor for detecting cyanide in mixed aqueous solution

A simple Schiff base sensor (L1) derived from N-(1-naphthyl) ethylenediamine dihydrochloride was designed and synthesised by simple chemistry procedures. The sensor exhibited a visible colour change observed by both colorimetric and fluorimetric responses for cyanide ion in aqueous solution. The detection of cyanide was performed via the nucleophilic attack of cyanide anion on the imine group of the sensor with a 1 : 1 binding stoichiometry. Moreover, test strips based on the sensor were fabricated, which served as convenient and efficient CN− test kits and the sensor L1 is a good way to detect hydrogen cyanide in aqueous extracts of sprouting potatoes.