Cyanide In Aqueous Media Research Articles

A Novel Colorimetric and Fluorometric Dual-Channel Chemosensor based on A Conjugated Perylene-Benzothiazole System for Highly Selective Detection of Cyanide in Aqueous Media.

A novel cyanine compound based on the conjugated perylene-benzothiazole system (PBI) as a colorimetric and fluorometric dual-channel sensor for cyanide (CN- ) detection was synthesized and characterized via UV-vis and fluorescence spectroscopy. PBI exhibited a high sensitivity and rapid optical response for CN- due to the intramolecular charge transfer (ICT) mechanism. The detection limit of PBI for CN- was 1.15×10-7 M in the mixture of DMSO/H2 O (1 : 1, v/v). Moreover, probe PBI demonstrated high selectivity and sensitivity for CN- over other common anions, including Cl- , Br- , F- , I- , AcO- , ClO4 - , HSO4 - , SO4 2- , NO2 - , NO3 - and SCN- . This work provided a simple and effective approach to trace the toxic CN- ion with rapid response, high selectivity, and sensitivity that is possibly applied in environmental control and agricultural management.

Molecular simulations of CRANADs to disclose a specific cyanide sensor in aqueous media

Chemical pollutants are the major contaminants in natural water samples and can be introduced either through natural processes or as a result of human activities. Some of the cations and anions such as cyanide, lead, mercury, and arsenic are toxic even at extremely low concentrations. The fatal effects of cyanide ions on the ecosystem have led to extensive research in the advancement of methods for rapid and specific detection of cyanide. We already reported the theoretical and experimental studies on the specific cyanide sensing capacity of the curcuminoid-BF2 complex, CRANAD-1. However, the theoretical investigation of the sensing mechanism of these types of CRANADs pointed out the key structural features which are capable of generating a better fluoroprobe for the rapid detection of cyanide in aqueous media even in trace quantities. Herein, we designed a novel selective and efficient fluorescent probe for cyanide detection based on these features. The DFT (Density Functional Theory) approach explores the significance of the probe in the quantitative detection of cyanide concentration in natural water samples. A comprehensive examination of the binding energies of the designed CRANADs in presence of various anions such as CN−, F−, Cl−, Br−, AcO−, SO42−and NO3− were carried out using the B3LYP level of density functional theory using SDD and 6-311++G** basis sets. Theλmaxabsorption values, FMO (Frontier Molecular Orbital), ESP (Electrostatic potential) plots and NBO (Natural Bond Orbital) analysis reveal the better cyanide sensing ability of the D–A–D (Donor-Acceptor–Donor) type CRANAD scaffold.

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.

A water-soluble azobenzene-dicyano pendant polymeric chemosensor for the colorimetric detection of cyanide in 100% aqueous media and food samples

A polymeric chemosensor (P1) was developed for the colorimetric detection of cyanide in aqueous media and cyanogenic food samples.

Novel fluorescent coumarin-thiazole based sensors for selective determination of cyanide in aqueous media

Novel colorimetric and fluorimetric fluorescent coumarin-thizole based chemosensors 4a-b were synthesized and characterized using spectroscopic methods. The photophysical properties of the sensors were determined in six solvents by UV–Vis and fluorosence spectrometers. The sensitivity and selectivity of 4a-b towards anions were investigated by absorption, emission and naked-eye detection methods in organic and aqueous media. Both sensors 4a-b showed selectivity to detecting of CN− besides other interference anions (F−, AcO− and H2PO4−) in aqueous solution. The sensing mechanism of the sensors were investigated by reversibility and 1H NMR titration studies and also supported by DFT calculations. Moreover, LOD values of 4a-b were calculated and the results can be used to detect CN− at a concentration lower than the WHO guideline (2.7 mM) for cyanide. Thermal studies of the compounds have shown that the 4a-b have enough thermal stability properties for application as optic dye. The compound 4b was fully spectroscopically characterized and its structure was unambiguously determined by single crystal X-ray crystallography.

A isophorone based colorimetric and ratiometric probe: Synthesis and rapid detection of cyanide in aqueous medium and its application in bioimaging

A simple colorimetric and fluorescent sensor for cyanide based on phenolic substituted dicyanoisophorone derivative (2) has been synthesized. The absorption spectra of chemosensor 2 showed large bathochromic shift (ca. 240 nm) upon titration with CN− while the solution color changed from yellow to green. The absorption ratios (A685/A446) responses of chemosensor 2 showed a favorable linear relationship with the CN− concentration and the detection limitation had been calculated to be 0.15 μM. Meanwhile, the fluorescence intensity of 2 can be quenched upon reacting with CN− over other anions. More importantly, chemosensor 2 can react instantaneously with cyanide in aqueous solution, and to visualize CN− in living HeLa cells by means of dramatic decrease of fluorescence intensity. Thus, the present sensor could be applicable in detecting cyanide ion both in natural water samples and biological systems conveniently.

Cyanide Sensing in Water Using a Copper Metallogel through "Turn-on" Fluorescence.

The development of fluorescent probes for selective detection of cyanide has gained considerable attention over the past two decades due to benefits like high selectivity as well as sensitivity, fast response, visual output, accurate quantification, and a simplified sample preparation procedure. However, the propensity of supramolecular gels toward fluorescence sensing of cyanide in aqueous medium is not well explored until now. Herein, we report the design and synthesis of a novel copper based metallogel capable of sensing cyanide in water by fluorescence "turn on". Toward this, a terpyridine attached poly(aryl ether) dendrone derivative (G1) is synthesized which forms gel and exhibits Aggregation Induced Emission (AIE). The addition and diffusion of copper ions to the gel resulted in the formation of a nonluminescent copper metallogel (CuG). The copper metallogel could selectively sense cyanide in water by a fluorescence "turn-on" signal due to the regeneration of the AIE active gel. The mechanistic pathways of the sensing have been studied, and the detection limit for sensing was found to be as low as 1.09 μM. A thin film of CuG was prepared by casting the gel and used as a test strip for the visual detection of cyanide in water.

A new naphthopyran-based chemodosimeter with aggregation-induced emission: Selective dual-channel detection of cyanide ion in aqueous medium and test strips

A novel green emissive AIE active probe, a naphthopyran-malononitrile conjugate (NPM), was utilized for selective dual channel (colorimetric and fluorimetric) sensing of CN− ions in DMSO-water (2/3, v/v, pH = 7.4) solution. The nucleophilic addition of CN− ion on the dicyano-vinyl group breaks the π-electron conjugation, thereby restricting intra-molecular charge transfer(ICT) process in the probe NPM and leading to a visual color change and observable spectral changes. NPM shows good selectivity for CN− ions with the LOD of 4.27 × 10−7 M, which renders it a candidate probe for cyanide detection in aqueous environments. For the practical applicability, NPM-coated paper strips were prepared for convenient, on-site detection of cyanide in aqueous medium.

Ruthenium-based phosphorescent probe for selective and naked-eye detection of cyanide in aqueous media

A simple molecular phosphorescent Ru(II) probe P1 has been synthesized by the reaction of 5-aldehyde-2,2′-bipyridine with ruthenium(II) chlorides under mild conditions. The probe upon interaction with different cation and anion showed high selectivity and sensitivity for cyanide ion (CN‒) through phosphorescence “turn-on” response in aqueous solution (60% water) with a detection limit of 0.75 μM. The significant phosphorescence enhancement (~ 30-fold) is attributed to the nucleophilic addition of cyanide ion to the aldehyde groups of the ruthenium complex in 3 : 1 stoichiometry, in which a naked-eye sensitive orange red color of solution changed to a yellow. The generation of cyanohydrin species through nucleophilic addition has been confirmed by 1H NMR, FT-IR and mass spectra. Based on the color change of the solution, a visual colorimetric strip was prepared, which also showed good detection performance on cyanide ion with quick response time. The prominent efficiency of the Ru(II) probe proved the potential possibility of application in biosystems relating with cyanide ion.

Gas chromatography-mass spectrometric identification of cyanide using a nucleophilic substitution based derivatization with S-phenyl benzenethiosulfonate.

A novel, simple and efficient analytical method for GC-MS based identification of cyanide has been developed using a single step nucleophilic substitution based derivatization of cyanide in aqueous medium. The nucleophilic substitution reaction of cyanide with S-phenyl benzenethiosulfonate results in the formation of phenyl thiocyanate as a cyanide derivative and it was found that the relative response of the resultant cyanide derivative was much higher than that of the cyanide derivatives resulting from disulfide based derivatizing agents. The sample preparation protocol for the identification of cyanide in aqueous samples was also optimized with the new derivatizing agent. Derivatization followed by liquid-liquid extraction was employed for the preparation of aqueous samples containing cyanide salts. The resultant samples were subjected to GC-MS analysis for the identification of the cyanide derivative. Under optimized conditions, the detection and quantification limits for cyanide aqueous samples were found to be 0.075 μg mL-1 and 0.25 μg mL-1 respectively. The calibration curve had a linear relationship with y = 0.086x - 0.076 and r2 = 0.997 for the working range of 0.25 μg mL-1 to 50 μg mL-1. The intraday RSDs were between 2.24 and 8.17%, and the interday RSDs were between 2.22 and 12.85%. The method can also be successfully employed for the identification of hydrogen cyanide in aqueous medium. The applicability of the present method was demonstrated by analysing a real sample from apple seed extraction.

Highly sensitive turn-off fluorescent detection of cyanide in aqueous medium using dicyanovinyl-substituted phenanthridine fluorophore.

Herein, the turn-off fluorescence sensor of 2-((4′-(7,8,13,14-tetrahydrodibenzo[a,i]phenanthridin-5-yl)-[1,1′-biphenyl]-4-yl)methylene)malanonitrile (7) was developed for the recognition of CN− ions and studied using different spectroscopic techniques. The selective recognition of CN− ions by 7 was investigated via UV-vis spectroscopy and fluorescence studies in acetonitrile solvent, which exhibited an obvious color change from orange to colorless under 365 UV light. The sensor compound 7 possesses a high binding constant (Ka) for CN− ions in the order of 5.22 × 106 M−1. The results from the interference studies revealed that probe 7 shows high sensing selectivity and sensitivity for CN− ions over other competitive anions. Probe 7 interacts with cyanide to form a 1 : 1 adduct, and this mechanism was further verified by 1H NMR titration, Job's plot analyses and DFT studies. The sensor probe 7 exhibits advantages such as low limit of detection (LOD) of 39.3 nM, fast response and sensing in a wide pH range of 3 to 11. The practical application of 7 was successfully demonstrated for the determination of CN− ions in test paper strips and various water samples.

A new colorimetric and ratiometric fluorescent probe for selective recognition of cyanide in aqueous media.

A simple naphthopyran derivative (L) has been synthesized as a colorimetric and ratiometric fluorescent probe for cyanide sensing in the aqueous DMSO medium and paper strips. The nucleophilic addition of CN- to this probe blocks the π-conjugation and the intramolecular charge transfer (ICT) transition between naphthopyran and benzoindolium moieties and consequently results in remarkable color and spectral changes. Upon addition of cyanide, L displayed a ratiometric fluorescence response with a blue shift of the peak position and a noticeable color change from fuchsia to colorless within 90s. The probe exhibits high selectivity and sensitivity toward CN- over other anions and the detection limit was calculated to be 7.56×10-7M, which is well below the WHO cyanide standard in drinking water (1.9μM). In addition, the excitation and emission of the probe were within the visible wavelength range, which could benefit an application of the probe in an inexpensive portable cyanide sensor. The sensing ability of L has been successfully applied in real water samples. Furthermore, test strips based on L were fabricated, which can act as convenient and efficient test kits for detecting CN-.

Tuning the recognition properties of urea based receptor towards cyanide in aqueous medium: Effect of fluorine substitution on strength and selectivity of the anion receptor.

In this report, we have successfully tuned the selectivity and sensitivity of an anion receptor L1 by substituting electron withdrawing natured fluorine atoms directly on to the rim of the phenyl ring. Despite the fact that, we have two electron withdrawing natured nitro substituents on the other side of receptor L1; two fluorine substitutions made dramatic change in the sensing ability as well as the selectivity of the receptor L1 towards anions. The acetonitrile solution contains L1 with tetrabutyl ammonium salts of fluoride, cyanide, acetate and dihydrogen phosphate results sudden color changes from yellow to brown; almost negligible spectral/color change for azide and bifluoride, where as there is no color change observed with any other anionic guests with L1. Solution state binding studies of L1 are carried out by UV-Vis spectrometry titration in 100% acetonitrile and it is found to be the receptor L1 selectively binds cyanide, phosphate and fluoride stronger than acetate; it is also found that receptor binds fluoride 100 times stronger than that of the receptor L and L1 has almost similar efficiency in binding towards acetate ion (AcO-). The strength of the receptor L1 towards fluoride, cyanide, acetate and dihydrogen phosphate bindings are found to be in the order of 1.271 × 105 M-1 > 1.245 × 105 M-1 > 1.368 × 103 M-1, 1.23 × 103 M-1 respectively. When we used aqueous environment (10% of water in acetonitrile) as testing solvent system, the receptor L1 selectively sense cyanide ion. Over all, strength of the receptor is increased towards anions with an increasing the number of fluorine atom onto the receptors. Here in we have also prepared a reference compound L2 in which the receptor molecule is substituted with only one fluoride atom. The acetonitrile solution of reference receptor L2 with help of naked-eye colorimetric experiment and spectrometric ammonium salts of fluoride, cyanide, acetate and bifluoride results sudden color changes from faint-yellow to brown in color. Unlike receptor L1, receptor L2 does not recognize H2PO4-, but instead of H2PO4-, it recognizes bifluoride as evidenced from UV-Vis spectroscopic and naked-eye colorimetric studies.

Selective "Turn-On" Fluorescent Sensor for Cyanide in Aqueous Environment and Test Strips.

A new very sensitive and selective fluorescent phenothiazine probe for the recognition of cyanide ions in an aqueous environment was prepared. The detection mechanism depends on the nucleophilic addition of cyanide ions to the fluorescent probe to result in fluorescent change go together with color change from purple to yellow. The prepared phenothiazine sensor was employed for invention of test strips able to recognize cyanide in aqueous media. It was found that the phenothiazine probe could selectively detect cyanide ions. When adding cyanide anions, the color of the yellow phenothiazine solution in dichloromethane changed to yellowish green, while a stronger green emission was monitored under UV lamp. Furthermore, the existence of 10 equivalents of other anions, including AcO-, HSO4-, Cl-, Br-, I-, H2PO4-, did not result in apparent variations in the UV-Vis absorption and fluorescent emission spectra. The recognition limit of phenothiazine probe to cyanide aions was 7.2 × 10-8 mol/L in dichloromethane.

Curcumin a colorimetric and fluorimetric cyanide probe in aqueous system and living cells

Curcumin is a visual, photometric and fluorometric sensor for cyanide in aqueous media.

Rapid and Selective Detection of Cyanide Anion by Enhanced Fluorescent Emission and Colorimetric Color Changes at Micromole Levels in Aqueous Medium

One main source of cyanide (CN−) exposure for mammals is through the plant consumption; thus, the sensitive and selective cyanide detection in plant tissue is a significant and urgent work. Here, a simple sensor N′‐(2,4‐dihydroxybenzylidene)naphtha[2,1‐b]furan‐2‐carbohydrazide (Q1‐3) was designed and synthesized for selective and sensitive dual‐channel detection of cyanide in aqueous medium (DMSO/H2O, 1:9, v/v). Acylhydrazone and phenolic hydroxyl groups on Q1‐3 are the recognition sites, and naphthofuran group is the signal report group. The intramolecular charge transfer between the benzene group and naphthofuran group was impeded because of the electron‐withdrawing groups (hydroxyl) on sensor Q1‐3. Interestingly, the sensor Q1‐3 exhibited an intramolecular charge transfer absorption band at 400 nm and emission band at 500 nm, respectively, directly realizing an “OFF–ON” response after the deprotonation process induced by cyanide anions in aqueous medium (DMSO/H2O, 1:9, v/v). Notably, this sensor was successfully applied to detect cyanide anions in food samples, which proves a very simple and selective platform for on‐site monitoring of cyanide in agriculture samples. In addition, the test strips and silica gel plates based on Q1‐3 were also fabricated, which could act as test kits and silica gel plates for convenient and efficient detection of cyanide anions.

A novel oligothiophene-based colorimetric and fluorescent “turn on” sensor for highly selective and sensitive detection of cyanide in aqueous media and its practical applications in water and food samples

Abstract A novel oligothiophene-based naked-eye colorimetric and fluorescent turn-on sensor 3TT with a typical donor-π-acceptor structure has been successfully developed, which displayed excellent selectivity and sensitivity for the dual-channel detection of toxic cyanide (CN−) in 70% aqueous THF media due to the nucleophilic addition of CN− to the β-conjugated position of the barbituric acid moiety of the sensor 3TT by hampering intramolecular charge transfer (ICT) process. The cyanide sensing mechanism was confirmed by optical spectral studies, FT-IR spectra, 1H NMR titration, HRMS spectra and DFT calculations. Sensor 3TT for the naked-eye detection of CN− in aqueous media exhibited high anti-interference ability, immediate response (20 s), extremely low detection limit (39.9 nM) as well as wide pH response range. Moreover, sensor 3TT displays excellent sensing performance in the solid state, and the 3TT-based test filter papers strips were used to conveniently and efficiently detect CN− in water by naked eyes. Furthermore, the sensor 3TT was successfully applied to the rapid detection of cyanide in real water samples, bitter seeds and food samples, demonstrating its great potential for practical applications in our daily life and environment.

A Turn‐On Fluorescence Chemosensor for Cyanide in Aqueous Media Based on a Nucleophilic Addition Reaction

AbstractWe synthesized a new cyanide (CN−) chemosensor CX based on a nucleophilic addition reaction prompted by cyanide ion, which could be used for highly selective and sensitive fluorescence turn‐on detection of cyanide in aqueous media. The CX showed selective fluorescence recognition for CN−, the miscellaneous competitive anions (F−, Cl−, Br−, I−, AcO−, H2PO4−, HSO4−, ClO4−, S2−, PO43−, CO32− and SCN−) did not lead to any significant interference. The detection limit of the sensor towards CN− is 1.15 × 10−7 mol•L−1. The sensor has been successfully applied to estimate the cyanide ion in seeds of cherries. Test strips based on CX were fabricated, which could be used as a convenient and efficient CN− test kit to detect CN− in aqueous solution for “in‐the‐field” measurement.

Near-infrared chemodosimetric probes based on heptamethine cyanine dyes for the “naked-eye” detection of cyanide in aqueous media

Two simple chemodosimetric probes (P1 and P2) based on heptamethine cyanine dyes have been synthesized for highly sensitive and selective detection of cyanide anions (CN−) in aqueous media. The probes with an immobilized indolium salt as the specifically nucleophilic addition reaction site for CN− exhibit absorption bands in the near-infrared (NIR) region (650–850nm). Upon the addition of CN−, the probes display a blue-shifted spectrum and result in apparent color change from green to brilliant yellow that can be easily observed by the naked eye even in the presence of other interfering anions such as F−, AcO−, Br−, NO2−, Cl−, SO42− and I−. There are good linear relationships between the fluorescence intensity of the probes and CN− concentrations, and the detection limits for P1 and P2 are estimated to be 0.017μM and 0.2μM, respectively. The sensing mechanism of the nucleophilic addition is confirmed by 1H NMR and mass spectroscopic analysis. In addition, the probe P2 is employed for cell imaging and the detection of CN− in living cells L929 is successfully realized.

A benzopyrylium–phenothiazine conjugate of a flavylium derivative as a fluorescent chemosensor for cyanide in aqueous media and its bioimaging

A new benzopyrylium–phenothizine conjugate (BP) has been synthesized for CN−sensing.