A useful scaffold based on acenaphthene exhibiting Cu2+ induced excimer fluorescence and sensing cyanide via Cu2+ displacement approach

Fluorometric and colorimetric sensor for selective detection of cyanide anion by dibenzosuberenone-based dihydropyridazine in aqueous solution

A new chemosensory based on deprotonation and intramolecular charge transfer (ICT) was developed to detect cyanide in food samples. Deprotonation was facilitated by increasing the acidity of the NH proton in the dibenzosuberenone-based dihydropyridazine chemosensor Pz3 with -CN substituents. Addition of cyanide to acetonitrile and aqueous acetonitrile solution (1/9) of Pz3 resulted in their significant color change from colorless to purple in visible light, accompanied by a strong red shift in the absorption spectrum. Meanwhile, the near-infrared (NIR) emission (ex. 525 nm, em. 670 nm) of Pz3- resulting from deprotonation showed fluorescence switching behavior to detect the cyanide anion. While the acidic NH protons interact with basic anions as F-, CN-, OAc- and H2PO4- in organic solution (MeCN), just CN ions interact with in aqueous organic solutions (H2O-MeCN 1/9 HEPES pH 7.4). The limit of detection of cyanide from the fluorescence spectrum is 80 nM, which is well below the value determined for drinking water by World Health Organization (WHO). The interference effect of cations and anions showed that Pz3 could play an important role in the determination of waste NaCN. In addition, Pz3 successfully carried out the selective detection of cyanide in food samples such as bitter almonds and sprouting potatoes.

Boron-Salphen Conjugate based Molecular Probe Exhibiting Fluorescence On-Off-On Response in Detection of Cu2+ and ATP through Displacement Approach

Synthesis and photophysical properties of a fluorescent probe HBD is described. Probe upon interaction with metal ions, anions and nucleoside pyrophosphates (NPPs) showed fluorescence quenching with Cu2+ due to chelation enhanced quenching effect (CHEQ). Moreover, interaction of ensemble HBD.Cu2+ with anions and NPPs showed fluorescence "turn-On" response with ATP selectively. "On-Off-On" responses observed with Cu2+ and ATP is attributed to an interplay between ESIPT and TICT processes. Cyclic voltammogram of probe exhibited quasi-reversible redox behaviour with three oxidation and two reduction potentials and the change in band gaps of probe suggested the interaction with Cu2+ and ATP. The 2 : 1 and 1 : 1 binding stoichiometry for an interaction between probe and Cu2+ (LOD, 62 nM) and ensemble, HBD.Cu2+ with ATP (LOD, 0.4 μM) respectively are realised by Job's plot and HRMS data. Cell imaging studies carried out to detect Cu2+ and ATP in HeLa cells. Also, the output emission observed with Cu2+ and ATP is utilized to construct an implication (IMP) logic gate. Test paper strips showed naked-eye visible color responses to detect Cu2+ and ATP. In real water samples probe successfully detected copper (0.03 μM) between 5-6.5 ppb level (ICP-MS method).

Efficient solid- and solution-state emissive reusable solvatochromic fluorophores for colorimetric and fluorometric detection of CN. Analyst 2024;149:1557-1570. [PMID: 38284868 DOI: 10.1039/d3an01697h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

In this work, a novel organic receptor, CPI [(E)-3-(4-(9H-carbazol-9-yl)phenyl)-2-(1H-benzo[d]imidazol-2-yl)acrylonitrile], was rationally designed and successfully fabricated for selective and sole recognition of CN- ions over other competitive anions through an obvious chromogenic and ratiometric emission change in DMSO. The distinct and prominent color change upon the addition of CN- can be attributed to the typical ICT process, which is induced by the deprotonation of acidic NH protons in the imidazole moiety. The sensor displayed strong solvatochromic effects in commonly used organic solvents such as n-hexane, toluene, diethyl ether, DCM, THF, DMF and DMSO. The chemical structure of the sensor was characterized by single-crystal X-ray diffraction, 1HNMR, 13CNMR, IR and mass spectroscopy. Significantly, the probe can function as a fluorescence-based sensor for the efficient detection of low-level water in organic solvents. The solid-state emission properties of CPI were successfully applied to recognise cyanide in a solid-state platform with naked eye-visualized distinct color change. The probe can be made reusable by adding TFA into the CN- treated probe solution. The detection limit of CPI towards CN- was determined to be 4.48 × 10-8 M. More importantly, the sensor is capable of detecting CN- in food samples and has been employed for wastewater treatment. Besides, easy-to-prepare CPI-coated test strips provide a simple, reusable and easy-to-handle protocol for the qualitative identification of CN- conveniently. Finally, density functional theory and time-dependent density functional theory were performed to verify the experimental outcomes theoretically.

A New Phenothiazine-Based Fluorescent Sensor for Detection of Cyanide

A new fluorescent sensor for the detection of CN- was developed based on the conjugation of phenothiazine fluorophore and benzofuran unit. By the nucleophilic attacking of CN- to the fluoroacetylamino group in the sensor, the additional reaction of CN- and carbonyl group induced the ICT (intramolecular charge transfer) effect in the molecule and caused the fluorescence quenching sensor. The titration experiments show that the sensor has good sensitivity, selectivity and quick response for CN-. In addition, the fluorescent detection of CN- in the living cell and zebrafish experiments demonstrated the value of the sensor in tracing the CN- in biological systems.

Nanoparticles Based Sensors for Cyanide Ion Sensing, Basic Principle, Mechanism and Applications

Rapidly detecting potentially toxic ions such as cyanide is paramount to maintaining a sustainable and environmentally friendly ecosystem for living organisms. In recent years, molecular sensors have been developed to detect cyanide ions, which provide a naked-eye or fluorometric response, making them an ideal choice for cyanide sensing. Nanosensors, on the other hand, have become increasingly popular over the last two decades due water solubility, quick reaction times, environmental friendliness, and straightforward synthesis. Researchers have designed many nanosensors and successfully utilized them for the detection of cyanide ions in various environmental samples. The majority of these sensors use gold and silver-based nanosensors because cyanide ions have a high affinity for these metals ions and coordinate through covalent bonds. These metal nanoparticles are typically combined or coated with fluorescent materials, which quench their fluorescence. However, adding cyanide ions etches out the metal nanoparticles, restoring their fluorescence/color. This principle has been followed by most nanosensors used for cyanide ion sensing. In this review, different nanosensors and their sensing mechanisms are discussed in relation to cyanide ions. The primary purpose is to compare the sensing abilities of these sensors, mainly their sensitivity, advantages, application and to find out research gaps for future work. In this review paper, the development made in nanosensors in the last thirteen years (2010-2023) was discussed and the nanosensors for cyanide ions were compared with molecular sensors while the nanosensors with the excellent limit of detection were highlighted.

Detection of cyanide and sulfide ions by different mechanisms using a fluorescent chemical sensor containing a fluorophore and a potential ligand for metal complexes

Here, we present a fluorescent chemical sensor for the simultaneous detection of CN- and S2- ions, which are highly toxic to humans and the environment. When the BPMA-Flu-Cu2+ complex comprising BPMA-Flu, a fluorophore combined with Cu2+, was used, the fluorescence was turned off. However, the fluorescence was turned on again by the addition of CN- and S2- ions. BPMA-Flu is a unique compound containing both a fluorophore and a ligand coordinated to a metal ion. This strategy using the proposed BPMA-Flu-Cu2+-based fluorescent chemical sensor facilitated quantitative analysis of CN- and S2- ions with high selectivity and sensitivity, despite varying detection mechanisms. The detection limit was as low as 290 nM and 74 nM for CN- and S2- ions, respectively. The sensor was selective and excluded other anions at concentrations 10-fold higher than those of CN- and S2- ions. The recovery rates did not exceed 10% of the original values for the detection of CN- ions in rainwater and tap water. These results indicate acceptable accuracy and precision for practical applications.

Single Organic Ligands Act as a Bifunctional Sensor for Subsequent Detection of Metal and Cyanide Ions, a Statistical Approach toward Coordination and Sensitivity

The detection of key ions in environmental samples has garnered significant attention in recent years in the pursuit of a cleaner environment for living organisms. Bifunctional and multifunctional sensors, as opposed to single-species sensors, have emerged as a rapidly developing field. Many reports in the literature have documented the use of bifunctional sensors for the subsequent detection of metal and cyanide ions. These sensors, consisting of simple organic ligands, form coordination compounds with transition metal ions, resulting in clear visible or fluorescent changes that facilitate detection. In some cases, a single polymeric material can act as a ligand and coordinate with metal ions, forming a complex that serves as a sensor for cyanide ion detection in biological and environmental samples through various mechanisms. Nitrogen is the most dominant coordinating site in these bifunctional sensors, with the sensitivity of the sensors being directly proportional to the denticities of ligands for metal ions, while for cyanide ions the sensitivity was found independent of the denticity of the ligands. This review covers the progress made in the field over the past fifteen years (2007-2022), with most ligands detecting copper (II) and cyanide ions, but with the capability to detect other metals such as iron, mercury, and cobalt as well.

Nucleophilic Approach to Cyanide Sensing by Chemosensors

Cyanide anion has wide use in industrial areas; however, it has a high toxic effect on the environment as waste. Moreover, plant seeds contain cyanide that is often consumed by human beings. Therefore, many studies are carried out to determine cyanide. Especially, optical sensors showing colorimetric and fluorimetric changes have been of considerable interest due to their easy, cheap, and fast responses. This review discusses recent developments in the colorimetric and fluorimetric detection of cyanide by nucleophilic addition to different types of receptors via the chemodosimeter approach. The sensitivity and selectivity of the sensors have been reviewed for changes in absorption and fluorescence, naked-eye detection, real sample application, and detection limits when interacting with cyanide.

Novel cyanide supramolecular fluorescent chemosensor constructed from a quinoline hydrazone functionalized-pillar[5]arene

Herein, we report a simple and novel approach for the design of fluorescent chemosensor through the self-assembly of functionalized monomer molecules. According to these approach, a novel supramolecular fluorescent chemosensor (SPMS) was successfully constructed by self-assembly of a quinoline hydrazone functionalized pillar[5]arene monomer PM. Interestingly, upon the addition of CN^-, the solution of SPMS instantly shows dramatic fluorescent enhancement and emitting bright blue emission. Meanwhile, the fluorescence quantum yields show distinct increase from 0.0582 of SPMS to 0.3952 of SPMS + CN^-. The detection limit (LOD) of SPMS for CN^- is 9.70 × 10^-8 M, which indicated high sensitivity. Moreover, the SPMS is selective for CN^- even in the presence of other anions, the fluorescent detection process of SPMS for CN^- was not interfered by other competitive anions (F^-, Cl^-, Br^-, I^-, N₃^-, OH^-, SCN^-, HSO₄^-, AcO^-, H₂PO₄^- and ClO₄^-). Notably, in the CN^- sensing process, the self-assembly structure of the supramolecular chemosensor SPMS didn't show any disassembly. This work provides a novel approach for instant detection of CN^- through a self-assembled supramolecular fluorescent chemosensor in aqueous system. Moreover, the test strips based on SPMS were fabricated, which could serve as convenient and efficient CN^- test kits.

Sensitive colorimetric detection of CN− and AcO− anions in a semi-aqueous environment through a coumarin–naphthalene conjugate azo dye

An efficient colorimetric chemosensor to detect anions in an aqueous medium.

Dual Sensing Performance of 1,2-Squaraine for the Colorimetric Detection of Fe3+ and Hg2+ Ions

A simple 1,2-squaraine based chemosensor material (SQ) has been reported to show dual sensing performance for colorimetric detection of Fe³⁺ and Hg²⁺ ions. Compared to common instrumental analysis, this method could provide fast and direct detection though colorimetric changes by the naked eye. The sensor has shown excellent selectivity over the other metal ions by tuning different solvent environments. The detection limit for Fe³⁺ could reach to 0.538 μM, which was lower than that in the environmental agency guideline (U.S. Environmental Protection Agency, U.S. EPA) in drinking water. And for Hg²⁺ detection, the limit was calculated as 1.689 μM in our case. A 1:1 binding mode between SQ⁻Fe³⁺ and SQ⁻Hg²⁺ ion were evidenced by Job's plot measurement and IR analysis. The proposed different binding mechanisms were also supported by Density Function Theory (DFT) calculation. All these findings provide a unique material and a simple, facile, and low cost colorimetric method for dual metal ions analysis and have shown preliminary analytical applications in industrial water sample analysis.

A selective chemosensor and fluorescence probe for relay recognition of cations and fluoride ions in aqueous media with logic gate function

Cation to anion relay recognition was studied for the first time with sequential specificity (Cu²⁺ → F^- or Co²⁺ → F^-) using a fluorescence "ON-OFF-ON" mechanism. L₁ is a receptor with high selectivity for F^-, Cu²⁺ and Co²⁺ ions in the solution of DMSO/H₂O with a 9:1 vol ratio. Absorption and fluorescence spectra were used to investigate the sensing process. Fluorescent emission intensity of L₁ at 324 is quenched (switch-Off) after the addition of Cu²⁺ and Co²⁺. Surprisingly, complex L₁ + Cu²⁺ or L₁ + Co²⁺ is restored with addition of F^- into the compound (switch-On). Consequently, implication (from emission) and inhibit (from absorption) logic gates are constructed at molecular level. The gates operate in fluorescence and absorption modes when Cu²⁺ and F^- or Co²⁺ and F^- are used as input materials and the fluorescence intensity signal as outputs. Based on reversible and reproducible system, a sequential memory unit with integrated ''Writing-Reading-Erasing-Reading'' behavior, is developed.

Oligothiophene-based colorimetric and ratiometric fluorescence dual-channel cyanide chemosensor: Sensing ability, TD-DFT calculations and its application as an efficient solid state sensor

An oligothiophene-based colorimetric and ratiometric fluorescence dual-channel cyanide chemosensor 3 T-2CN was reported. Sensor 3 T-2CN showed both naked-eye recognition and ratiometric fluorescence response for CN^- with an excellent selectivity and high sensitivity. The sensing mechanism based on the nucleophilic attack of CN^- on the vinyl CC bond has been successfully confirmed by the optical measurements, ¹H NMR titration, FT-IR spectra as well as the DFT/TD-DFT calculations. Moreover, the detection limit was calculated to be 0.19μM, which is much lower than the maximum permission concentration in drinking water (1.9μM). Importantly, test strips (filter paper and TLC plates) containing 3 T-2CN were fabricated, which could act as a practical and efficient solid state optical sensor for CN^- in field measurements.

Dicarbohydrazide based chemosensors for copper and cyanide ions via a displacement approach

Ligands attached to pyridine dicarbohydrazide were synthesized and characterized using NMR, FT-IR, elemental analysis, UV-visible spectroscopy, mass spectrophotometry, emission spectra and single crystal X-ray diffraction, and were assessed for their ability to sense copper and cyanide ions.

Effective ensemble system for the identification of CN− based on a cobalt(ii) complex: a logic gate mimic

A novel reaction-based sensor [4-hydroxy-6-methyl-3-(1-(3-methylpyridin-2-ylimine)ethyl)-2H-chromene-2-one-Co²⁺] has been synthesized for the sensitive and selective detection of CN⁻.

A benzimidazole functionalized NDI derivative for recyclable fluorescent detection of cyanide in water

An NDI-based chemosensor (L2) was synthesized via a one step reaction; L2 showed recyclable CN⁻ detection properties in water.

Metal-based optical chemosensors for CN- detection

This critical review focuses on recent advances (2010-2015) in the detection of cyanide anion via metal-based optical chemosensors in which a change in colour and/or fluorescence intensity (or emission wavelength) of a molecular metal complex is determined by the direct interaction of the metal centre with this anion.

Off-On-Off fluorescence behavior of an intramolecular charge transfer probe toward anions and CO2

The photophysical behavior of a newly developed fluorescent probe, tricyanoethylphenyl phenanthroimidazole (TCPPI) has been studied. Upon interaction of different class of anions TCPPI displayed naked-eye sensitive fluorescence "turn-on" response to detect selectively F(-) (0.98μM, 18.62ppb) and CN(-) (1.12μM, 29.12ppb) anions in acetonitrile (MeCN). Job's plot analysis revealed a 1:1 binding stoichiometry between probe and anions. The spectral data analysis and 1H NMR titration studies suggested about the affinity of F(-) and CN(-) anions with moderately acidic -NH fragment of imidazolyl unit of probe through deprotonation and H-bonding interaction. Moreover, the anion activated probe upon interaction with CO2 revived photophysical properties of probe, "On-Off-On" type fluorescence and enabled anion-induced CO2 sensing in the medium.

A highly selective colorimetric and "turn-on" fluorimetric chemosensor for detecting CN(-) based on unsymmetrical azine derivatives in aqueous media

A novel highly selective chemosensor S1 for cyanide based on unsymmetrical azine derivative was successfully designed and synthesized, which showed both colorimetric and fluorescence turn-on responses for cyanide ions in aqueous. This structurally simple chemosensor could detect CN(-) anion over other anions in aqueous solution DMSO/H2O (v/v=3:2) undergo deprotonation reaction. Results showed that the chemosensor S1 exhibited 50 fold enhancement in fluorescence at 530nm and showed an obvious change in color from colorless to yellow that could be detected by naked eye under the UV-lamp after the addition of CN(-) in aqueous solution. Moreover, the detection limit on fluorescence response of the sensor to CN(-) is down to 6.17×10(-8)M by titration method. Test strips based on S1 were obtain, which could be used as a convenient and efficient CN(-) test kit to detect CN(-) in aqueous solution.

Selective and sensitive colorimetric sensor for CN− in the absence and presence of metal ions (Cu2+/Ni2+): mimicking logic gate behaviour

Enone based anion sensors have significance due to their colorimetric reaction upon deprotonation and variable occurrence in the conjugated moiety.

A colorimetric and “turn-on” fluorimetric chemosensor for the selective detection of cyanide and its application in food samples

A simple cyanide highly selective and sensitive fluorescent enhanced chemosensor HY had been designed and synthesized.

A coumarin-indole based colorimetric and "turn on" fluorescent probe for cyanide

A novel coumarin-indole based chemodosimeter with a simple structure was designed and prepared via a condensation reaction in high yield. The probe exhibited very high selectivity towards cyanide on both fluorescence and UV-vis spectra, which allowed it to quantitatively detect and imaging cyanide ions in organic-aqueous solution by either fluorescence enhancement or colorimetric changes. Confirmed by (1)H NMR and HRMS spectra, the detection mechanism was proved to be related with the Michael addition reaction induced by cyanide ions, which blocked the intramolecular charge transfer (ICT) of the probe. Moreover, the probe was able to be utilized efficiently in a wide pH range (7.5-10) with negligible interference from other anions and a low detection limit of 0.51μM. Application in 5 kinds of natural water source and accurate detection of cyanide in tap water solvent system also indicated the high practical significance of the probe.

A simple Michael acceptor type quinoline derivative for highly selective sequential recognition of CN− and Cu2+ in aqueous solution

A 2-(quinolin-2-ylmethylene) malononitrile (6) chemosensor capable of sensing cyanide and copper ions was designed through a sequential reaction with the two toxins. Significant color changes could be distinguished by the naked eye on UV lamp.

Benzoquinone–imidazole hybrids as selective colorimetric sensors for cyanide in aqueous, solid and gas phases

One of the five new receptors developed, which works via the formation of H-bonds, exhibited a striking visible colour change selectively with cyanide ion in solid, aqueous and gas phases.

Smart excimer fluorescence probe for visual detection, cell imaging and extraction of Hg2+

Smart pyrene-based simple fluorescent probes 2 and 4 were designed, synthesized and characterized by different spectroscopic methods.

Aggregation deaggregation influenced selective and sensitive detection of Cu2+ and ATP by histidine functionalized water-soluble fluorescent perylene diimide under physiological conditions and in living cells

A novel PDI-HIS probe detects Cu²⁺ to form aggregated nonfluorescent complex. Addition of 0.58 ppm ATP to this complex causes its rapid disaggregation thereby recovering the fluorescence by ∼99% in vitro and in A549 living cells.

A new calix[4]arene based molecular probe for selective and sensitive detection of CN− ions in aqueous media

A molecular diagnostic probe for CN⁻ ions in aqueous media promises the development of disposable filter paper strips for field applications.