Showing papers on "Cyanide published in 2022"

A benzothiazole-based new fluorogenic chemosensor for the detection of CN− and its real-time application in environmental water samples and living cells

Abstract: Since the cyanide ion is used in a wide range of industries and is harmful to both human health and the environment, a number of research efforts are dedicated to creating fluorescence sensors for the detection of cyanide (CN−). Herein, for the fluorescence detection of CN−, a new highly selective and sensitive sensor 2-(3-(benzo[d]thiazol-2-yl)-4-hydroxybenzylidene)-1H-indene-1,3(2H)-dione (BID) was created by conjugating a benzothiazole moiety with 1H-indene-1,3(2H)-dione. The donor and acceptor components of this hybrid receptor were covalently connected through a double bond. The nucleophilic addition of a cyanide anion to the BID inhibits the intramolecular charge transfer (ICT) transition, resulting in spectral and colour alterations in the receptor. When the solvent polarity was increased from n-hexane to methanol, this molecule exhibited a bathochromic shift in the emission wavelength (610 to 632 nm), suggesting the presence of a solvatochromic action. The sensor BID has shown strong specificity towards CN− by interrupting its internal charge transfer (ICT), resulting in a significant change in the UV-vis spectrum and a notable blue shift in the fluorescence emission spectrum. The cyanide anion (CN−) is responsible for the optical alterations observed by BID, as opposed to the other anions examined. The detection limit was 5.97 nM, significantly less than the WHO's permitted amount of CN− in drinking water. The experimental findings indicate that BID's fluorescence response to CN− is pH insensitive throughout a wide pH range of 6.0 to 12.0. The interaction mechanism between the BID and CN− ions has been studied by HRMS, 1H-NMR titration experiments, FT-IR, and DFT, which confirmed the nucleophilic addition of CN− on vinylidene and subsequent disturbance of ICT. Additionally, we demonstrated the real-time detection application of CN− in environmental water samples and live-cell imaging.

Synthesis of Co/CeO₂ hetero-particles with abundant oxygen-vacancies supported by carbon aerogels for ORR and OER

Abstract: It is highly significant for the fabrication of rechargeable metal-air batteries to develop cost-efficient and high-performance electrocatalysts of bifunctionality for both oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). Herein, we demonstrate a hybrid composed of CeO2-decorated Co nanoparticles supported on three-dimensionally porous carbon aerogels (Co-CeO2/C aerogels) as a superior bifunctional electrocatalyst. The preparation of Co-CeO2/C aerogels depends on the formation of a novel CeCl3/K3Co(CN)6-chitosan (CS) hydrogel, during which the cyanide groups of K3Co(CN)6 combines the hydroxyls in CS by hydrogen bridges, accompanying with the substitution of chloride groups in CeCl3 by cyanide groups in K3Co(CN)6. The electron spin resonance offers a convincing proof that numerous oxygen vacancies were found in Co-CeO2/C aerogels after the introduction of CeO2. The developed Co-CeO2/C aerogels showed an outstanding electrochemical performance for both OER and ORR in comparsion with RuO2 and Pt/C catalysts in 0.1 M KOH solution. A small overpotential (380 mV) and a low Tafel slope (99 mV dec-1) were observed for OER, while the half-wave potential (0.75 V) and the onset potential (0.92 V) were high for ORR. The superior performance could be put down to the multihole heterostructure, multiple components and abundant oxygen vacancies. It was very helpful for the adsorption and the catalyzation of the reactants and the efficient mass transport of reagent/product. This work paves a neoteric method to synthesize a bifunctional hybrid catalyst with a highly efficient performance of energy conversion and storage.

Quinoline based thiosemicarbazones as colorimetric chemosensors for fluoride and cyanide ions and DFT studies

Abstract: Abstract High toxicity and extensive accessibility of fluoride and cyanide ions in diverse environmental media encouraged attention for scheming well-organized probes for their detection. Keeping in mind we have designed and synthesized thiosemicarbazone-based chemosensors RB-1, RB-2 and RB-3 for the detection of fluoride and cyanide ions. The structural elucidation of the synthesized chemosensors is done by employing different analytical techniques including nuclear magnetic resonance and electronic absorption specrtoscopies. Admirable detection limit, binding constant and fast response time (2 s) to F − and CN − ions enlarged the applications of these chemosensors. Additional confirmation of the sensing ability of these chemosensors is derived from DFT and TDDFT calculations with M06/6-311G(d,p) method by performing FMO, UV–Vis, QTAIM and global reactivity parameters elucidation. Overall results point out that investigated chemosensors are suitable candidates for sensing the F − ions. These chemosensors were successfully applied to detect F − ions in a commercial toothpaste sample.

Cyanide as a primordial reductant enables a protometabolic reductive glyoxylate pathway

Abstract: Investigation of prebiotic metabolic pathways is predominantly based on abiotically replicating the reductive citric acid cycle. While attractive from a parsimony point of view, attempts using metal/mineral-mediated reductions have produced complex mixtures with inefficient and uncontrolled reactions. Here we show that cyanide acts as a mild and efficient reducing agent mediating abiotic transformations of tricarboxylic acid intermediates and derivatives. The hydrolysis of the cyanide adducts followed by their decarboxylation enables the reduction of oxaloacetate to malate and of fumarate to succinate, whereas pyruvate and α-ketoglutarate themselves are not reduced. In the presence of glyoxylate, malonate and malononitrile, alternative pathways emerge that bypass the challenging reductive carboxylation steps to produce metabolic intermediates and compounds found in meteorites. These results suggest a simpler prebiotic forerunner of today's metabolism, involving a reductive glyoxylate pathway without oxaloacetate and α-ketoglutarate-implying that the extant metabolic reductive carboxylation chemistries are an evolutionary invention mediated by complex metalloproteins.

A Sustainable Decision Support System for Drinking Water Systems: Resiliency Improvement against Cyanide Contamination

Abstract: Maintaining drinking water quality is considered important in building sustainable cities and societies. On the other hand, water insecurity is an obstacle to achieving sustainable development goals based on the issues of threatening human health and well-being and global peace. One of the dangers threatening water sources is cyanide contamination due to industrial wastewater leakage or sabotage. The present study investigates and provides potential strategies to remove cyanide contamination by chlorination. In this regard, the main novelty is to propose a sustainable decision support system for the dirking water system in a case study in Iran. First, three scenarios have been defined with low ([CN−] = 2.5 mg L−1), medium ([CN−] = 5 mg L−1), and high ([CN−] = 7.5 mg L−1) levels of contamination. Then, the optimal chlorine dosage has been suggested as 2.9 mg L−1, 4.7 mg L−1, and 6.1 mg L−1, respectively, for these three scenarios. In the next step, the residual cyanide was modelled with mathematical approaches, which revealed that the Gaussian distribution has the best performance accordingly. The main methodology was developing a hybrid approach based on the Gaussian model and the genetic algorithm. The outcomes of statistical evaluations illustrated that both injected chlorine and initial cyanide load have the greatest effects on residual cyanide ions. Finally, the proposed hybrid algorithm is characterized by the multilayer perceptron algorithm, which can forecast residual cyanide anion with a regression coefficient greater than 0.99 as a soft sensor. The output can demonstrate a strong positive relationship between residual cyanide- (RCN−) and injected chlorine. The main finding is that the proposed sustainable decision support system with our hybrid algorithm improves the resiliency levels of the considered drinking water system against cyanide treatments.

Spiropyran and spironaphthoxazine based opto-chemical probes for instant ion detection with high selectivity and sensitivity to trace amounts of cyanide

Abstract: Colorimetric chemical sensors with instant detection of cyanide ion, as a dangerous effluent from various industries and high toxicity, are nowadays of significant importance. Here, photochromic spironaphthoxazine (SNO) and hydroxyethyl spiropyran (SPOH) were synthesized and employed to detect some cations as well as trace amount of cyanide ion with reasonable selectivity and sensitivity among different anions. Their spiro forms were not triggered by metal cations, while their UV-induced open-ring isomers became susceptible to establish a dye-cation complex. The opto-chemical results demonstrated that neither SPOH nor SNO could make reliable discrimination between different metal cations, even after UV irradiation. However, both SPOH and SNO were selectively attached to CN− with a 1:1 stoichiometric ratio (from Job’s plot), even in the presence of several other anions and in the absence of UV irradiation. This was approved by 1HNMR and UV–vis spectroscopies. Besides, the interaction of CN− with SPOH and SNO was approved by visual color change from colorless (λmax of 345 nm for both) to dark yellow with λmaxs of 416 and 412 nm for those linked to hydroxyethyl merocyanine (MC-CN) and meronaphthoxazine (MNO-CN), respectively. The detection limits of SPOH (0.091 µM) and SNO (0.094 µM) sensors toward CN− were lower than its permitted level in drinking water by WHO (1.9 µM). These were also checked and compared with other spiro-based sensors. The obtained results demonstrate the potentiality of SNO and SPOH as promising colorimetric and opto-chemical sensors with wide linear dynamic detection range for determining trace amount of CN−.

Spiropyran and spironaphthoxazine based opto-chemical probes for instant ion detection with high selectivity and sensitivity to trace amounts of cyanide

Abstract: Colorimetric chemical sensors with instant detection of cyanide ion, as a dangerous effluent from various industries and high toxicity, are nowadays of significant importance. Here, photochromic spironaphthoxazine (SNO) and hydroxyethyl spiropyran (SPOH) were synthesized and employed to detect some cations as well as trace amount of cyanide ion with reasonable selectivity and sensitivity among different anions. Their spiro forms were not triggered by metal cations, while their UV-induced open-ring isomers became susceptible to establish a dye-cation complex. The opto-chemical results demonstrated that neither SPOH nor SNO could make reliable discrimination between different metal cations, even after UV irradiation. However, both SPOH and SNO were selectively attached to CN− with a 1:1 stoichiometric ratio (from Job’s plot), even in the presence of several other anions and in the absence of UV irradiation. This was approved by 1HNMR and UV–vis spectroscopies. Besides, the interaction of CN− with SPOH and SNO was approved by visual color change from colorless (λmax of 345 nm for both) to dark yellow with λmaxs of 416 and 412 nm for those linked to hydroxyethyl merocyanine (MC-CN) and meronaphthoxazine (MNO-CN), respectively. The detection limits of SPOH (0.091 µM) and SNO (0.094 µM) sensors toward CN− were lower than its permitted level in drinking water by WHO (1.9 µM). These were also checked and compared with other spiro-based sensors. The obtained results demonstrate the potentiality of SNO and SPOH as promising colorimetric and opto-chemical sensors with wide linear dynamic detection range for determining trace amount of CN−.

A Few Pt Single Atoms Are Responsible for the Overall Co‐Catalytic Activity in Pt/TiO2 Photocatalytic H2 Generation

Abstract: The use of single atoms (SAs) has become a highly investigated topic in heterogeneous catalysis, electrocatalysis, and most recently also in photocatalysis. In the field of photocatalysis, Pt SAs on TiO2 have been reported to be a highly efficient co‐catalyst in solar H2 production. Herein, the deposition of Pt SAs and nanoparticles on titania nanosheets is investigated. In particular, the Pt species responsible for the high co‐catalytic activity using a cyanide leaching process is elucidated. It is shown that neither Pt0 species nor the majority of Pt SAs do significantly contribute to the co‐catalytic activity of platinum on TiO2. In fact, >90% of the Pt of a standard deposition are non‐active and can be removed by cyanide leaching without activity loss—as a consequence, the remaining Pt SAs amount to a remarkable turnover frequency of 4.87 × 105 h−1 for H2 evolution.

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

Abstract: • A naphthalene based optical sensor was developed for detection of cyanide ions (CN – ). • The receptor shows distinct “on-off” color and fluorescence changes upon the alteration of free CN – levels in solution. • The sensing mechanism between the receptor and CN – was clearly presented. • The receptor was successfully applied to detect CN – in 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.

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

Abstract: 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.

Synthesis of gold nanoclusters-loaded lysozyme nanoparticles for ratiometric fluorescent detection of cyanide in tap water, cyanogenic glycoside-containing plants, and soils

Abstract: The modification of protein-stabilized gold nanoclusters with fluorophores has been intensively applied for the ratiometric detection of biomolecules, metal ions, and anions. This study developed a straightforward strategy to prepare lysozyme nanoparticle-encapsulated gold nanoclusters (LysNP-AuNCs) as a dual-emission probe for the ratiometric sensing of cyanide through fluorescence resonance energy transfer (FRET) without the conjugation of additional fluorophores. The reduction of gold ion precursors with lysozyme generated lysozyme-stabilized AuNCs under an alkaline pH, which were demonstrated to self-assemble into nanoaggregates during the formation of AuNCs. The aggregated lysozyme molecules on the AuNCs were treated with glutaraldehyde, triggering the conversion of the aggregated lysozymes into blue-emitting lysozyme nanoparticles. As a result, the AuNCs were well distributed inside a single lysozyme nanoparticle, as demonstrated by transmission electron microscopy. The presence of cyanide triggered the etching of the AuNCs in the LysNP-AuNCs, leading to the suppression of FRET from lysozyme nanoparticle to AuNCs. The LysNP-AuNC probe was implemented for FRET detection of cyanide with a linear range of 3-100 μM. Additionally, the selectivity of the LysNP-AuNC probe for cyanide toward other anions was remarkably high. The practicality of the proposed probe was evaluated by quantifying cyanide in tap water and soils and monitoring the liberation of hydrogen cyanide from cyanogenic glycoside-containing foods.

Rhodamine 6G-based efficient chemosensor for trivalent metal ions (Al3+, Cr3+ and Fe3+) upon single excitation with applications in combinational logic circuits and memory devices.

Abstract: A new rhodamine 6G-based chemosensor (L3) was synthesized and characterized by 1H, 13C, IR and mass spectroscopy studies. It exhibited an excellent selective and sensitive CHEF-based recognition of trivalent metal ions M3+ (M = Fe, Al and Cr) over mono and di-valent and other trivalent metal ions with prominent enhancement in the absorption and fluorescence intensity for Fe3+ (669-fold), Al3+ (653-fold) and Cr3+ (667-fold) upon the addition of 2.6 equivalent of these metal ions in the probe in H2O/CH3CN (7 : 3, v/v, pH 7.2). The corresponding Kd values were evaluated to be 1.94 × 10-5 (Fe3+), 3.15 × 10-5 (Al3+) and 2.26 × 10-5 M (Cr3+). The quantum yields of L3, [L3-Fe3+], [L3-Al3+] and [L3-Cr3+] complexes in H2O/CH3CN (7 : 3, v/v, pH 7.2) were found to be 0.0005, 0.335, 0.327 and 0.333, respectively, using rhodamine-6G as the standard. The LODs for Fe3+, Al3+ and Cr3+ were determined by 3σ methods and found to be 2.57, 0.78 and 0.47 μM, respectively. The cyanide ion snatched Fe3+ from the [Fe3+-L3] complex and quenched its fluorescence via its ring-closed spirolactam form. Advanced level molecular logic devices using different inputs (2 and 4 input) and a memory device were constructed.