A ratiometric chemodosimeter for highly selective naked-eye and fluorogenic detection of cyanide

A simple indole-based chemosensor (1) with a very low molecular weight of 207 g mol⁻¹ has been synthesized for the highly reactive and selective detection of CN⁻ in aqueous media, even in the presence of other anions, such as F⁻, Cl⁻, Br⁻, AcO⁻, S₂⁻${{\mathrm{S}}_2}^{-}$, SCN⁻, NO₂⁻${{\text{NO}}_2}^{-}$, NO₃⁻${{\text{NO}}_3}^{-}$, CO₃⁻${{\text{CO}}_3}^{-}$, BzO⁻, H₂PO₄⁻${{\mathrm{H}}_2{\text{PO}}_4}^{-}$, and HSO₄⁻${{\text{HSO}}_4}^{-}$. The sensor achieves rapid detection of cyanide anion in 2 min, and the pseudo-first-order rate constant is estimated as 1.576 min⁻¹. The colorimetric and ratiometric fluorescent response of the sensor to CN⁻ is attributable to the addition of CN⁻ to the electron-deficient dicyanovinyl group of 1, which prevents intramolecular charge transfer. The sensing mechanism is supported by density functional theory and time-dependent density functional theory calculations. Moreover, sensor 1 exhibits both high accuracy in determining the concentration of CN⁻ in real samples and 1-based test strips can conveniently detect CN⁻ without any additional equipment. The detection limit of the sensor 1 (1.1 μM) for cyanide is lower than the maximum permissible level of CN⁻ (1.9 μM) in drinking water.     

A naked-eye,selective and sensitive chemosensor for fluoride ion

Effect of the addition of six different anions on the absorption and fluorescence spectra of acridine yellow G (AYG) was examined. Only the F⁻ anion could induce a visible color change observable with naked eye and a strong fluorescence quenching with K _SV of 8.3 × 10⁴ mol⁻¹ L in CH₃CN solutions. Calculated results of the interaction between the F⁻ anion and acridine yellow G using the B3LYP/6-31G(d) program showed that the intermolecular charge transfer through the formation of an H-bond between AYG and F⁻ is an essential sensor mechanism.     

A highly selective chromo- and fluorogenic dual responding fluoride sensor: naked-eye detection of F- ion in natural water via a test paper

A highly selective and sensitive chromogenic and fluorogenic dual signal responding fluoride-sensor 1, comprising a Ru-bipy fluorophore (bipy = 2,2'-bipyridine) and a 2,4-dinitrophenylhydrazone chromophore was prepared and spectroscopically characterized. Uv-vis titrations with F- revealed the appearance of a new intense absorption band centered at about 580 nm which was accompanied by a dramatic change in color from yellow to magenta, with the association constant logK being 6.71 +/- 0.04. Fluorescence spectra showed that upon addition of F-, the emission intensities enhanced significantly without any change in the excited and emission wavelengths, suggesting a potential photoinduced electronic transfer (PET) signaling transduction mechanism. An easy-to-prepare test paper which was obtained by putting a filter paper into an acetonitrile solution of 1, can detect F- in aqueous media, indicating the potential application for detecting F- in natural aqueous environments without any spectroscopic instrumentation. Spectroscopic titrations of the free ligand were also studied for comparison.     

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

Research on Chemical Intermediates - Three new benzoquinone–imidazole ensembles possessing varying number (0, 1 and 2) of electron-withdrawing bromo substituents on the quinone ring have been...     

A highly selective chemosensor derived from benzamide hydrazones for the detection of cyanide ion in organic and organic-aqueous media: design,synthesis, sensing and computational studies

ABSTRACT

A new, highly sensitive and selective chemosensing method has been developed for the detection of cyanide ion using benzamide hydrazone receptors (R1-R4). The sensing ability of these compounds towards CN^? in the presence of Br ^?, HSO₄ ^?, Cl^?, OH^?, I^?, F^?, AcO^?, NO₂ ^? and NO₃ ^? in DMF and DMF-Aqueous mixture (DMF:H₂O, 9:1 v/v) was investigated. The binding characteristics of the probe with cyanide ions carried out by ¹ H NMR titrations indicated the deprotonation of N-H group through H-bond interactions between benzamide hydrazones and cyanide ions; it has been theoretically supported by DFT. The binding constant (Ka) and stoichiometry of the host–guest complex formed was calculated by the Benesi–Hildebrand (B–H) plot, and strong interaction of the probe with CN^- ions forming a 1:2 binding stoichiometry has been noted in this study. In a DMF and aqueous medium for CN^? ion, the lower limit of detection (LOD in ppm) is compared to the limit of quantification (LOQ in ppm), which is quite better in terms of sensitivity.     

Direct determination of benzylnitriles using the cyanide ion selective electrode

The response characteristics of the solid state cyanide ion selective electrode towards some benzylnitriles are investigated. In 10M KOH solution, the electrode exhibits nearly Nernstian response over the concentration range of 10^–2 to 10^–4 M of various substituted benzylnitriles with an anionic slope of 53–59 mV/concentration decade. The response time varies from 10 to 20 min depending on both the nature of the substituent group and the concentration of the nitrile compound. Direct potentiometric measurement of some nitrile compounds at the concentration level of 0.01 to 1 mg/ml shows an average recovery of 98.2% and a mean standard deviation of 2.3%. Many nitrogen functional groups do not interfere.     

A colorimetric probe for the selective naked-eye detection of Pb(II) ions in aqueous media

A new colorimetric molecular probe based on a 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) dye selectively binds Pb(II) ions in aqueous solutions, allowing for highly sensitive naked-eye detection.     

A convenient and selective synthesis of unsymmetrical benzoins via the cyanide ion catalyzed cleavage of benzils

The cyanide ion-catalyzed cleavage of benzils is used for the generation of various ‘masked’ acyl intermediates. The reaction of these intermediates with various aldehydes furnishes the corresponding esters of unsymmetrical benzoins in very good yields. A variety of unsymmetrical benzoin derivatives are synthesized in this way, including ferrocene derivatives. The hydrolysis of benzoin esters and their subsequent oxidation affords the corresponding unsymmetrical benzoins and benzils in high yield.     

A naked-eye sensing ensemble for the selective detection of citrate--but not tartrate or malate--in water based on a tris-cationic receptor

Citrate 3 can be selectively detected in aqueous solvents even in the presence of malate or tartrate using a naked-eye detection system based on the complex between tris-cation 1 and carboxyfluorescein 2.     

Microcalorimetric studies on catalase reaction and inhibition of catalase by cyanide ion

As Chance et al. [1, 2 and 3] proposed, the decomposition of hydrogen peroxide catalyzed by catalase is an overall first-order reaction. In this paper, we have studied this enzyme-catalyzed reaction with a thermokinetic method. The rate constant and the molar reaction enthalpy of this reaction have been measured. At 310.15 K and pH=8.2, k_cat=1.75×10⁶ l mol⁻¹ s⁻¹, Δ_rH_m=88.99 kJ mol⁻¹. Furthermore, we have studied the competitive inhibition of catalase by cyanide ion and reported some correlated parameters.     

A colorimetric and fluorescent sensor for sequential detection of copper ion and cyanide

A simple cation sensor 1 ((E)-9-((2-hydroxynaphthalen-1-ylimino)methyl)-1,2,3,5,6,7-hexahydropyrido[3,2,1-ij]quinolin-8-ol) bearing both a julolidine moiety and a naphthol moiety was designed and synthesized as a colorimetric sensor for Cu²⁺. In methanol solution of 1, the presence of Cu²⁺ led to a distinct naked-eye color change from yellow to purple. The proposed sensing mechanism might be attributed to the decrease in internal charge transfer band. Moreover, the resulting 1–Cu²⁺ complex sensed cyanide in a fluorometric way via fluorescent changes. These results demonstrate a novel type of the sequential recognition of Cu²⁺ and CN⁻ using two different sensing methods, color change, and fluorescence.     

2,1,3-Benzoxadiazole-based selective chromogenic chemosensor for rapid naked-eye detection of Hg2+ and Cu2+

We report a simple twisted intramolecular charge transfer (TICT) chromogenic chemosensor for rapid and selective detection of Hg(2+) and Cu(2+). The sensor was composed of an electron-acceptor 4-fluoro moiety and an electron-donor 7-mercapto-2,1,3-benzoxadiazole species where the S together with the 1-N provided the soft binding unit. Upon Hg(2+) and Cu(2+) complexation, remarkable but different absorbance spectra shifts were obtained in CH(3)CN-H(2)O mixed buffer solution at pH 7.6, which can be easily used for naked-eye detection. The sensor formed a stable 2:1 complex with Cu(2+), and both 2:1 and 3:1 complexes with Hg(2+). While alkali-, alkaline earth- and other heavy and transition metal ions such as Na(+), Mg(2+), Mn(2+), Co(2+), Ni(2+), Ag(+), Zn(2+), Pb(2+) and Cd(2+) did not cause any significant spectral changes of the sensor. This finding is not only a supplement to the detecting methods for Hg(2+) and Cu(2+), but also adds new merits to the chemistry of 4,7-substituted 2,1,3-benzoxadiazoles.     

Dual-functional Au-Fe3O4 dumbbell nanoparticles for sensitive and selective turn-on fluorescent detection of cyanide based on the inner filter effect

We demonstrate for the first time that bifunctional Au-Fe(3)O(4) dumbbell nanoparticles can be used for sensitive and selective turn-on fluorescent detection of cyanide based on the inner filter effect, and a "magnetic concentration-washing process" is proposed to effectively reduce the interference of dye pollution.     

Colorimetric probes based on anthraimidazolediones for selective sensing of fluoride and cyanide ion via intramolecular charge transfer

Probes based on anthra[1,2-d]imidazole-6,11-dione were designed and synthesized for selective ion sensing. Each probe acted as strong colorimetric sensors for fluoride and cyanide ions and exhibited intramolecular charge transfer (ICT) band, which showed significant red-shifts after addition of either the F(-) or CN(-) ion. One of the probes (2) showed selective colorimetric sensing for both cyanide and fluoride ions. In organic medium, 2 showed selective color change with fluoride and cyanide, whereas in aqueous organic medium it showed a ratiometric response selectively for cyanide ion.     

An organopalladium chromogenic chemodosimeter for the selective naked-eye detection of Hg(2+) and MeHg(+) in water-ethanol 1 : 1 mixture

An organopalladium chemical dosimeter of Hg(2+) that methylates Hg(2+), undergoing a colour change in 1 : 1 ethanol-water with submicromolar sensitivity, gives rise to an aqua-palladium complex that is methylated by MeHg(+) in the presence of a dithiol compound, undergoing another colour change, thus making the system suitable for the naked-eye detection of Hg(2+) and MeHg(+), two environmentally important species of Hg(2+).     

A highly sensitive and selective naked-eye probe for detection of Fe3+ based on a 2,5-bis[3-benzyl-2-methylbenzothiazole]-croconaine

A highly sensitive and selective naked-eye probe, 2,5-bis[3-benzyl-2-methylbenzothiazole]-croconaine (BMC) for sensing of Fe³⁺ was synthesized and characterized. The BMC can selectively recognize Fe³⁺ among the test cations (Ni²⁺, Mg²⁺, Cu²⁺, Ca²⁺, Na⁺, K⁺, Cr³⁺, Ag⁺, Ba²⁺, Zn²⁺, Pb²⁺, Al³⁺, Fe³⁺, Cd²⁺, Co²⁺) in DMF/H₂O (4:1, v/v). The binding constant of BMC-Fe³⁺ was evaluated by using Benesi-Hildebrand plot. Simultaneously, the binding mode of BMC-Fe³⁺ was supporting by Job's plot, ESI-MS, FT-IR and ¹H NMR. Correspondingly, the morphology of chelate complex was investigated by FESEM. Moreover, Fe³⁺ and EDTA could be employed as inputs and the fluorescence emission intensity which was 816 nm as output so that a molecular logic gate could be realized.     

The effect of sulfide ion chemisorption on the kinetics of gold dissolution in cyanide solutions

The effect of sodium sulfide additions (from 5 × 10^?6 to 2 × 10^?5 M) on the kinetics of gold dissolution in cyanide solutions of the following composition, M: 0.1 KCN, 0.02 KAu(CN)₂, 0.5 K₂SO₄, pH 10–13 is studied. Hydrosulfide ions are shown to exert a strong catalytic effect on the dissolution kinetics of this metal in a potential range where their adsorption is accompanied by the formation of polysulfides (?0.2 < E < 0.4 V). The reaction acceleration depend on the potential and is 100-fold for E ? 0.1 V. The effect becomes more pronounced as the concentration of hydrosulfide ions increases to 10^?4 M and is almost pH-independent in the pH range from 10 to 13. An attempt to explain the found relationships is undertaken.     

Metal ion capillary zone electrophoresis with direct UV detection: Separation of metal cyanide complexes

Mixtures of cyanide complexes of iron(III), copper(I), iron(II), nickel(II), chromium(III), mercury(II), palladium(II), silver(I), cadmium(II), zinc(II), cobalt(II), and cobalt(III) have been separated by capillary zone electrophoresis using a fused silica capillary and 20 mM phosphate buffers containing 1–2 mM sodium cyanide. The complexes were detected by direct UV absorpticn at 214 nm; detection limits are in the mid ppb range for all metals except cadmium and zinc. The different detectability of various metal cyanide complexes enables the application of the method to the analysis of complex matrices such as cyanide plating bath solutions.     

A highly selective colorimetric and ratiometric two-photon fluorescent probe for fluoride ion detection

A naphthalimide-based highly selective colorimetric and ratiometric fluorescent probe for the fluoride ion displayed both one- and two-photon ratiometric changes. Upon reaction with the F(-) (TBA(+) and Na(+) salts) anion in CH(3)CN as well as in aqueous buffer solution, probe 1 shows dramatic color changes from colorless to jade-green and remarkable ratiometric fluorescence enhancements signals. These properties are mechanistically ascribed to a fluoride-triggered Si-O bond cleavage that resulted in a green fluorescent 4-amino-1,8-naphthalimide.