Recognition Of Cyanide Research Articles

Off-On-Off Cascade Recognition of Cyanide, Mercury, and Aluminum Using N/5-Monosubstituted Rhodanines.

This study aims to synthesize N- and 5-monosubstituted rhodanine derivatives as ion-sensing organics and investigate their sensing abilities. Following an easy and green approach to synthesis, the anion-sensing properties of the rhodanines were studied using colorimetric detection and spectroscopic methods. As a result of studies, rhodanines are found to be highly solvent-controlled colorimetric and fluorescent cyanide, mercury, and aluminum sensors. The stoichiometry of the interaction between CN- and both probes was determined to be 1:1 using Job's plot analysis. The binding constants (Ks) of CN- to 5-arylRh and N-arylRh were calculated to be 3.25 × 104 and 7.07 × 104 M-1, respectively, demonstrating their high affinity for cyanide ions. The limits of detections for the 5-arylRh and N-arylRh were also determined as 356 and 617 nM, respectively. In addition to detecting CN-, 5-arylRh also serves as a specific turn-off sensor for mercury and aluminum when cyanide and hydroxide are present. This enables the fluorescence intensity to be toggled on/off by alternating the addition of CN-/OH- and Hg2+/Al3+. Furthermore, the LOD values for Hg2+ and Al3+ with 5-arylRh-CN- and 5-arylRh-OH- were determined to be 414 nM and 1.35 μM, respectively. Furthermore, the turn-on binding mechanisms of 5-arylRh and N-arylRh with cyanide ions were elucidated, and the experimental band gap (highest occupied molecular orbital/least unoccupied molecular orbital) energy values corroborated the proposed mechanism. Additionally, the interaction mechanism of the probes with CN- was further investigated by using the 1H NMR technique. Collectively, these findings suggest that 5-arylRh, N-arylRh, and 5-arylRh-CN- hold promise as selective and sensitive candidate sensors for CN-, Hg2+, and Al3+ ions.

Rationally designed dual channel reversible probe for cyanide recognition in aqueous medium with solid-state sensing abilities

A novel chromogenic azo-azomethine chemosensor, namely 2-((E)-(2-(benzo[d]thiazol-2-yl) hydrazineylidene)methyl)-4-((E)-phenyldiazenyl)phenol (referred to as L), was rationally designed and synthesized. The molecular structure of L was established using various spectroscopic and spectrometry techniques including NMR, FT-IR and mass. The spectral profile including absorption and fluorescence were recorded in solvents of varying polarity. The sensor responsiveness towards different anions was evaluated visually and established using UV–vis spectroscopy and NMR studies. A binary solution of DMSO/H2O (6:4, v:v) was used for anion recognition studies. A color change from colorless to yellow was noticed upon addition of CN– ion to the probe (L) solution. The developed probe was found to be very sensitive towards CN– ion with a detection limit of 21 nM. Benesi-Hildebrand plot revealed a binding constant of 1.2*103 M-2and the binding stoichiometry of 1:2 was confirmed using Job’s plot. 1H NMR studies were utilised to ascertain the recognition mechanism which revealed the CN– ion assisted deprotonation of N-H and O-H group of L. The recognition mechanism established using NMR technique has been supported theoretically by DFT based studies. Additionally, cost-effective paper strips coated with L has been proved to be a convenient tool for detecting CN– ion in aqueous solutions. The reversibility and reusability of the developed probe was also investigated in both solution as well as solid state using trifluoroacetic acid (TFA) without any loss of the sensitivity of the developed probe. Moreover, the developed probe recognises cyanide ion in environmental samples with around 100 % recovery. The practical application of the Logic gate response of L was confirmed by paper strip experiment.

Tailored fluorophore design: Enhancing selectivity for cyanide ion sensing in water and food samples, and innovative device development

A rigid fluorophore unit of Julolidine/coumarin fused with an indolium-conjugated system was built for the immediate and effective recognition of cyanide ions in a 90 % aq. DMSO solution. The probes are capable of displaying better sensitivity/selectivity for the cyanide ion over a wide range of other interfering ions. The probe JI showed an instant colorimetric variation, whereas the modified probe JCI showed both colorimetric and fluorimetric variation with cyanide ion. The observed detection limit values indicated excellent sensitivity of the probe to the cyanide ion. HRMS and 1H NMR studies confirmed that the mechanism of detection of CN− is via the nucleophilic attack on the electron-deficient indolium moiety of the molecule. Moreover, the probes are well proficient in selective recognition of cyanide in various real time applications (test strips, electronic sensor kit, food and water sample analysis).

A Coumarin-Hemicyanine Deep Red Dye with a Large Stokes Shift for the Fluorescence Detection and Naked-Eye Recognition of Cyanide.

In this study, we synthesized a coumarin-hemicyanine-based deep red fluorescent dye that exhibits an intramolecular charge transfer (ICT). The probe had a large Stokes shift of 287 nm and a large molar absorption coefficient (ε = 7.5 × 105 L·mol-1·cm-1) and is best described as a deep red luminescent fluorescent probe with λem = 667 nm. The color of probe W changed significantly when it encountered cyanide ions (CN-). The absorption peak (585 nm) decreased gradually, and the absorption peak (428 nm) increased gradually, so that cyanide (CN-) could be identified by the naked eye. Moreover, an obvious fluorescence change was evident before and after the reaction under irradiation using 365 nm UV light. The maximum emission peak (667 nm) decreased gradually, whilst the emission peak (495 nm) increased gradually, which allowed for the proportional fluorescence detection of cyanide (CN-). Using fluorescence spectrometry, the fluorescent probe W could linearly detect CN- over the concentration range of 1-9 μM (R2 = 9913, RSD = 0.534) with a detection limit of 0.24 μM. Using UV-Vis spectrophotometry, the linear detection range for CN- was found to be 1-27 μM (R2 = 0.99583, RSD = 0.675) with a detection limit of 0.13 μM. The sensing mechanism was confirmed by 1H NMR spectroscopic titrations, 13C NMR spectroscopy, X-ray crystallographic analysis and HRMS. The recognition and detection of CN- by probe W was characterized by a rapid response, high selectivity, and high sensitivity. Therefore, this probe provides a convenient, effective and economical method for synthesizing and detecting cyanide efficiently and sensitively.

Precisely designed NIR based conjugated framework as a solid state emitter for selective recognition of cyanide ion in solid state and cancer cells

Cyanide is undoubtedly dangerous and fast acting chemical employed in various industrial applications with toxic side effects, which raises urgent need for its monitoring. In this context, oxazolonaphthoimidazo[1,2-a]pyridine-malononitrile (ONIM) conjugate linked by vinyl linkage was designed, synthesized and characterised by FT-IR, NMR and mass spectrometry. The developed probe has been evaluated for the colorimetric and fluorometric detection of cyanide ion. An obvious color change with unique rapid “turn-off” fluorometric response was observed within 5 s upon addition of CN– thus reflecting its better acuteness and sensitivity over other competing anions. The developed probe exhibits a detection limit of 9.54 nM which is very low in comparison to maximum permitable amount of cyanide in drinking water (1.9 µM). The probe is stable within the pH range of 2–9 and suitable for the recognition of CN– in the pH range of 7 to 10, specially at neutral pH conditions. The chemodosimetric approach based detection mechanism was authenticated by 1H NMR titration and DFT calculations. The solid state applications were established by utilising ONIM impregnated TLC plates and filter paper in cyanide recognition. The solid state emissive behaviour of ONIM offers on-spot detection of the cyanide anion. Additionally, the practicability of ONIM has been extended in live cell imaging of CN– in human breast cancer cell (MDA-MB-231), which revealed a “turn-off” fluorescence response for the probe in the presence of CN– ion.

Cyanide Recognition and Phase‐Selective Removal of Toxic Cationic Dyes from Water Using a New Naphthalimide‐coupled Poly (aryl ether) Gelator

AbstractIn the work, a new naphthalimide‐linked poly(aryl ether) gelator 1 has been designed and synthesized. It forms gels in various organic and aquous organic solvents and exhibits aggregation‐induced enhancement of emission (AIEE) through the tuning of gelling solvent. Gels are of good viscoelastic nature showing higher magnitude of G′ over G′′ and exhibit fibrous morphology. Among the different gels, DMSO : H2O (7 : 3, v/v) gel with considerable rigidity selectively detects CN− over the other anions via deprotonation mechanism and involves a gel‐to‐sol colour change. In addition, n‐butanol : H2O (9 : 2, v/v) gel shows the same property. The water in gelling medium has the pertinent role in anion recognition selectivity, aggregation and AIEE. While in solution F− interferes in CN− sensing, there is no interference of it in the gel state. Besides sensing, n‐butanol gel of 1 removes the toxic cationic dyes from wastewater to the extent of 98–99 % in phase selective manner.

Photo responsive dyads for fast recognition of cyanide and fluoride in aqueous media

Three new photo responsive molecular dyads have been synthesized by the reaction of 4-hydrazino-N-benzyl-1,8-naphthalimide with different diketone derivatives (benzil, acenaphthene quinone, pyrene-4,5-dione). Naph-diones have been observed to exhibit photo tautomerization plausibly due to proton transfer from the 4-amino-naphthalimide, –NH to the carbonyl, >CO moiety of the dione when photo-irradiated in a polar aprotic solvent (THF). The synthesized dyads also respond to protonation and de-protonation on change of pH of the medium and exhibited well defined multi-colour solvatochromism in different solvents. The synthesized derivatives have been determined to be highly sensitive towards critical anions (e.g., fluoride and cyanide ions). Observed photo tautomerization has been confirmed by DFT calculations and solvent induced spectral changes. The recognition of cyanide and fluoride in dilute solutions has been observed to be very fast and required less than 15 s response time. Mechanism of interaction has been confirmed through 1H NMR and UV-Vis spectra. Details of experiments conducted, energy calculations and spectral observations made for ionic recognition have been described.

Selective and sensitive colorimetric cyanide recognition in aqueous medium and food samples based on Ni(II) complex chemosensor

Since cyanide is highly toxic that can lead to respiratory arrest and death, it is important to develop practical diagnostic methods for the sensing of cyanide. In this study, the colorimetric sensing of cyanide was achieved by a nickel complex (NiC) sensor with thiourea binding sites. NiC was prepared and characterized by 1H NMR, single-crystal X-ray crystallography, FTIR, and Mass spectra. When the cyanide and sulfide ions were added to NiC sensor, the color changed from light yellow to canary yellow and pale yellow to golden yellow, respectively. NMR titration results confirmed that the colorimetric response toward cyanide resulted from the deprotonation and formation of a guest–host complex. A binding mechanism is proposed based on the mass spectra, 1H NMR titration, and stoichiometry studies. The binding constant and detection limit of the NiC sensor toward cyanide was also investigated. The detection limits of NiC toward cyanide and sulfide reached 35.4 nM and 28.7 nM, respectively, lower than the World Health Organization (WHO)-allowed cyanide concentration in drinking water. The NiC complex possesses high selectivity to cyanide and sulfide through deprotonation of the –NH- protons. The detection of trace amounts of cyanide ions in natural food samples, such as cassava flour and sprouting potatoes, was also achieved by the NiC sensor.

A benzoxazole-based fluorescent ‘off-on-off’ probe for cascade recognition of cyanide and Fe3+ ions

This article introduced a benzoxazole-based (NT) photoluminescence 'off–on-off' probe for sequential detection of cyanide (CN–) and iron (III) (Fe3+) ions, respectively in H2O/DMSO (1:1 v/v) medium. Probe NT quickly produced a strong blue fluorescence due to the introduction of CN– ions, found to be 1:1 binding stoichiometry, mainly due to the disruption of excited state intramolecular proton transfer (ESIPT) because of deprotonation of hydroxy (–OH) functional group present in the salicylimine moiety. The resulting deprotonated NT is further employed for detecting Fe3+ ions by turn-off fluorescence response and binding affinity found in the 1:3 stoichiometry ratio. The detection thresholds for CN– and Fe3+ ions are estimated to be 23 nM and 5.70 μM, respectively, much lower than the permissible maximum contamination level predicted by Environmental Protection Agency (EPA). For the practical utilization of our fluorescence sensor NT as an on-site detector, we have demonstrated a paper strip-based test kit experiment to quantify traces of CN– ions in stocks of related analytes. The ability of NT and deprotonated NT to detect CN– and Fe3+ ions, respectively, demonstrated that it might be a sensing tool for real sample analysis.

Gelation-induced enhanced emission active stimuli-responsive low-molecular-weight organogelator: dual-channel recognition of cyanide from water and food samples with superhydrophobic surface formation

A mechano–thermo-responsive and superhydrophobic GIEEgen for dual-channel cyanide sensing from real-world water and food samples is reported.

Imidazole-derived new colorimetric/fluorometric chemosensor for the sensitive recognition of CN− ions: Real-time application in food samples and fluorescence bio-imaging

On account of the supreme toxicity of CN− ions in the physiological systems, it is essential to develop a sensitive chemosensor to detect cyanide ions. Herein, we designed a new 5-(3-(4,5-diphenyl-1H-imidazol-2-yl)-2-hydroxybenzylidene)-2,2-dimethyl-1,3-dioxane-4,6-dione (BMA) sensor, which exhibits tremendous colorimetric as well as fluorometric behaviour towards CN− ions. This could be due to the nucleophilic attack of CN− ions on the dione-vinyl site, which induces intramolecular charge transfer (ICT) capabilities. The cyanide recognition mechanism of BMA was verified by optical experiments such as UV–visible and fluorescence spectroscopy, NMR, and mass analysis. Moreover, the structural characterization was done by 1H NMR titration and HRMS analysis, and the molecular orbital interactions were studied by TDDFT calculations. The sensor BMA exhibited a rapid response towards CN− ions (10 sec) with low detection limit (7.87 nM), great pH stability in the physiologically applicable pH range (6–12) and had good sensitivity and selectivity towards CN− ions. Encouraged by these detection properties, we successfully used sensor BMA to determine CN− ions in real water and food samples. To validate the colorimetric behavior of the sensor BMA, test paper strip experiments were carried out in the laboratory. We also extensively studied the effect of the sensor in Escherichia coli (E.coli) bacterial cells.

Naked-eye colorimetric cyanide detection by monocarbonyl analogue of curcumin

The sensing properties of a monocarbonyl analogue of curcumin (C1-MAC) for cyanide recognition were investigated by UV-Vis absorption spectroscopy. C1-MAC was designed as an alternative of curcumin, since it has similar properties, but does not suffer from its well-known disadvantages, such as tedious preparation from toxic and expensive starting materials and structural instability. C1-MAC exhibited excellent selectivity for cyanide ion over other anions including NO3−, NO2−, Cl−, Br−, H2PO4−, and even over alkaline anions such as SO42−, CH3COO−, F− and HCO3−. The detection mechanism was confirmed by 1H nuclear magnetic resonance experiments, Job's method of continuous variation and the comparative study of the O-methyl protected analogue. The response of the probe to cyanide was easily observed by naked eye with immediate color change of the C1-MAC solution from yellow to deep red. In addition, the application of the probe on fabricated test strips was examined. The test papers demonstrated excellent selectivity towards CN− without significant response from interfering ions such as CH3COO−, F− and HCO3−, showing that this technique is valuable for the convenient detection of cyanide in 100% water samples.

Nanomolar Level Fluorogenic Detection of Cyanide with an Amide Functionalized Zirconium Metal‐Organic Framework and Its Application in Real‐World Cyanide Monitoring

AbstractThis work contains synthesis of a di‐amide linker based Zr(IV) metal‐organic framework (MOF, 1) and its characterization with by PXRD, elemental analysis, FE‐SEM, EDX and FT‐IR analysis and application for the detection of toxic cyanide in aqueous medium. Furthermore, the physicochemical stability of the sensor was judged by the thermogravimetric analysis (TGA) and PXRD analysis. TGA curve of 1 displayed that the thermal stability of the probe was up to 230 °C. The MOF material was stable in sensing medium and in wide pH range (pH=2–8) which were confirmed by PXRD analysis of the recovered samples. The surface area (BET) of this porous sensor was 672 m2/g with a pore volume of 0.36 cm3/g at p/po=0.5. Guest free form of the MOF material (1’) displayed its high efficiency for the fluorescence recognition of cyanide (CN−) with an extraordinary limit of detection of 76.4 nM in aqueous medium. Comparable recognition time (10 min) as the other available chemosensors of CN− ion and sensing of CN− using easily portable paper strips make this probe an extraordinary chemosensor for CN− ions. Together with paper strip based sensing, detection of CN− in apple seeds, various real water samples and wide ranges of pH solutions are the special features of the probe. The abstraction of amide proton by CN− ion favors “turn‐on” sensing, which was revealed by 1H‐NMR titration. This sensor of cyanide can also be used as luminescent switch due to its reversible nature of sensing.

Selective and sensitive turn on fluorescence cyanide recognition in aqueous medium based on Zn(II)-hydrazone metal complex chemosensor.

Detection and quantification of the cyanide ion (CN- ) has attracted considerable attention because of its extreme toxicity. A novel Zn(II)-complex, applicable as a fluorescent chemosensor for CN- recognition, was synthesized in excellent yields from the reaction of zinc sulfate with the novel hydrazone: 3-(amino-9H-purin-yl)-N'-(hydroxybenzylidene) propanehydrazide. The structures of the hydrazone (L) and the zinc-hydrazone complex (L.Zn) were characterized by ultraviolet-visible spectrophotometry, Fourier-transform infrared spectrometry, mass spectrometry, proton- and carbon-13-nuclear magnetic resonance. The sensing performance of the proposed chemosensors, L and L.Zn, towards common ions was investigated via naked-eye studies as well as absorption and emission spectral analysis. Hydrazone (L) efficiently functioned as a fluorescence sensor for aluminum ions (Al3+ ) and zinc ions (Zn2+ ) with large binding constants, and exhibited colorimetric and fluorometric responses for several basic anions: OH- , CO3 2- , HCO3 - , HSO3 - , CH3 COO- and CN- . However, L.Zn showed quick, sensitive and specific enhancement of fluorescence intensity towards CN- anion, and a linear relationship was observed as the concentration of CN- varied from 1 to 14 μM. The detection limit was determined to be 0.14 μM, which is lower than the 1.9μM maximum value recommended by the World Health Organization for drinking water. The practical performance of the sensor was successfully demonstrated using various environmental water samples spiked with cyanide ion.

Two novel tetraphenylethylene-skeleton salamo-type fluorescent probes: specific recognition of cyanide through different response patterns

The possible sensing mechanism of probes TPES1 and TPES2 towards CN−ions.

Cover Feature: A new mechanism for selective recognition of cyanide in organic and aqueous solution (Eur. J. Org. Chem. 30/2020)

Cover Feature: A new mechanism for selective recognition of cyanide in organic and aqueous solution (Eur. J. Org. Chem. 30/2020)

A new mechanism for selective recognition of cyanide in organic and aqueous solution

A simple colorimetric and fluorimetric chemosensor 3,5‐dinitro‐(N‐phenyl)benzamide (DNBA), was synthesized for selective determination of cyanide anion in organic and aqueous solutions via novel chemodosimeter approach. The chemosensor DNBA showed a chromogenic and fluorogenic selective response to CN– against competing anions such as F–, AcO–, and H2PO4– in organic (DMSO and ACN) and in aqueous solutions (in DMSO/H2O: 8:2, v/v). The intensive colorimetric and fluorimetric color changes were observed in ambient light and UV‐light (λex. 365 nm) after cyanide interacted with DNBA. A method that can be used in the synthesis of new biologically active benzisoxazole compound was described by the reaction of DNBA with TBACN and KCN in DMSO or DMSO/H2O, respectively. All interaction mechanisms between DNBA and cyanide and fluoride anions were demonstrated by experimental studies using various spectroscopic methods such as UV/Vis, fluorescence, 1H/13C NMR, and mass spectrometry as well as X‐ray diffraction method. In addition, the experimental results were also explained with theoretical data. The spectroscopic results showed that cyanide interacts with three different mechanisms; deprotonation, nucleophilic aromatic substitution, and formation of benzisoxazole ring.

Concurrent detection and treatment of cyanide-contaminated water using mechanosynthesized receptors.

The development of receptors that can detect as well as treat cyanide ions in aqueous samples is indispensable for environmental protection. Herein, we present the bulk solvent-free and instant green synthesis of a series of turn-on fluorimetric probes that can specifically detect the deadly poison cyanide among various anions and metal ions in water. Selective recognition of cyanide by the mechanosynthesized compounds is even observable by the naked eyes, which remained unaffected in the presence of various challenging species. NMR spectroscopic investigation supports the chemodosimetric sensing of cyanide by the receptors. A remarkable 55-83 fold fluorescence enhancement by the probes enabled us to reach a limit of detection (LOD) in the range of 8-26 ppb, well below the permissible limit of cyanide in drinking water. Being minuscule soluble in water, cyanide treatment studies with the ionophores showed greater than 99% reduction in the free cyanide concentration after three consecutive cycles of operation. Furthermore, the compounds can be used as sensitive probes for the estimation of cyanide in human blood serum in physiological conditions. Overall, the results presented in this article will certainly find great use in the area of cyanide pollution with regard to simultaneous sensing and treatment of free cyanide, which is heretofore unprecedented.

Recognition of Cyanide by Urea-Based Bipodal Probe

Two urea based colorimetric receptors were developed. The receptor L showed a exclusive selectivity of cyanide over the other anions in acetonitrile solution and exhibited Intramolecular charge Transfer (ICT). It was studied by UV-vis spectroscopy and their binding ability was explored by using Job’s plot and Benesi-Hildbrand routes. From that the receptor L, it recognize CNanions and it indicates 1:1 stoichiometric ratio and the receptor L 1 (monofluoro substituted) does not recognize any anions. Finally the (difluoro substituted) receptor L shows good sensitivity, selectivity towards cyanide.

Electron Deficient π-hole Assisted Colorimetric Probe for Selective Cyanide Recognition.

Here in, simple and novel electron deficient pi-Hole assisted amide based colorimetric receptor synthesized for cyanide recognition which produce yellow to brownish red color change upon the addition of cyanide in acetonitrile medium. Cyanide has selectively recognized successfully with 1:1 stoichiometric ratio and 1.5523x104 M-1 association constant. Cyanide recognition study was carried out with UV-Vis absorption and FTIR-Analysis and association constant and stoichiometric ratio were calculated by Benasi-Hildebrand plot and job’s continues variation method respectively