A novel dual-channel chemosensor for CN- using asymmetric double-azine derivatives in aqueous media and its application in bitter almond

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.

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.

A novel coumarin derivative-modified cellulose fluorescent probe for selective and sensitive detection of CN- in food samples

In this work, a novel coumarin derivative-modified cellulose acetate (DCB-CA) was synthesized as a fluorescent probe for highly selective and sensitive determination of CN^- in food samples. The DCB-CA was synthesized by using CA as a skeleton, and the coumarin derivative as the fluorophore. The DCB-CA obtained was characterized by different methods including FTIR, SEM, ¹H-NMR, TGA and UV-vis spectroscopy. The DCB-CA exhibited a significant "turn-off" fluorescence response to CN^-, accompanied by a distinct fluorescence color change from bright yellow to colorless. The detection limit of CN^- using DCB-CA was calculated to be 5.8 × 10^-7 M, which was much lower than the threshold limit of CN^- recommended by the World Health Organization (1.9 × 10^-6 M). Because of the favorable solubility and processability of the CA, the DCB-CA was easily processed into different fluorescent materials including fluorescent films and coatings. The fluorescent film obtained was also applied to the selective detection of CN^-. Furthermore, the DCB-CA was successfully applied to determine CN^- in food samples.

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.

Magnetic mesoporous nanomaterials with AIE properties for selective detection and removal of CN- from water under magnetic conditions

We have prepared a type of magnetic mesoporous nanomaterial with aggregation-induced emission properties (Fe₃O₄@mSiO₂@TPA@BA, hence abbr. FSTB) to detect and remove cyanide ions (CN^-) under magnetic conditions. FSTB has a large specific surface area and improved fluorescence performance to identify CN^-, and its superparamagnetic behavior plays an important role in removing CN^-. The magnetic sensor FSTB shows excellent selectivity and anti-interference for the detection of CN^- in aqueous solutions. It is obvious from the equation LOD = 3δ/S that the limit of detection (LOD) of FSTB for CN^- is significantly lower than the permissible level of CN^- in drinkable water recommended by the World Health Organization. Therefore, the magnetic sensor FSTB has a wide range of applications for detecting and removing harmful CN^-.

A simple fluorophore-imine ensemble for colorimetric and fluorescent detection of CN- and HS- in aqueous solution

Colorimetric and fluorescent detection of cyanide and hydrogen sulfide ions has been effected using a simple organic probe in H₂O:DMSO (20:80, v/v) medium. The probe exhibits a colour change from pale-yellow to red upon addition of these analytes under normal light and fluorescent change from green to red under UV lamp. Other competitive ions show no observable colour or fluorescence change. The binding constants of cyanide and hydrogen sulfide ions with the probe determined using fluorescence titration data are found to be 2.1 × 10⁴ and 1.6 × 10⁴ M^-1, respectively. The probe fluorimetrically detects the analytes in a wide pH range (4-10). ¹H and ¹³C NMR studies suggest that the probe senses cyanide ion through deprotonation and nucleophilic addition mechanism and hydrogen sulfide ion via deprotonation mechanism. Detection limits of cyanide and hydrogen sulfide are determined to be 0.15 and 1 μM, respectively. The practical utility of the probe has been demonstrated by same dual mode detection of cyanide in food materials like bitter almond, cassava flour and sprouting potato.

A new colorimetric and fluorescent probe based on Rhodamine B hydrazone derivatives for cyanide and Cu2+ in aqueous media and its application in real life

A simple selective colorimetric and fluorimetric chemosensor RD based on Rhodamine B hydrazone derivatives was designed and synthesized, which showed both colorimetric and fluorescence responses for cyanide and Cu²⁺ in aqueous solution with specific selectivity and high sensitivity. In the presence of cyanide, the sensor exhibited a visible color change from colorless to pale yellow by naked-eyes and rapidly produced a strong yellow fluorescence in aqueous solution. The detection limit on fluorescence response of RD sensor to CN^- is down to 3.54×10^-7M. In addition, compared to other metal ions such as Fe³⁺, Hg²⁺, Ag⁺, Ca²⁺, Cu²⁺, Co²⁺, Ni²⁺, Cd²⁺, Pb²⁺, Cr³⁺, Zn²⁺ and Mg²⁺ in aqueous solutions, RD could show both colorimetric and fluorescence responses rapidly for Cu²⁺. Notably, this sensor can be used as a molecular switch controlled by CN^- and H⁺ cyclically. Test strips based on RD were fabricated that could be used as a convenient and efficient CN^- and Cu²⁺ test kits. RD could detect cyanide in germinated potato, bitter almond and tap water. This chemosensor enabled detection of two ions, which do not need to rely on two different sensors.

A novel long-alkyl-chained acylhydrazone-based supramolecular polymer gel for the ultrasensitive detection and separation of multianalytes

By rationally introducing multi-self-assembly driving forces and coordination binding sites into the same molecule, a designed functional gelator, G, was synthesized. Next, a novel supramolecular polymer material, OGV (1% DMSO), was constructed and used for the ultrasensitive detection and separation of multianalytes in gel states. Interestingly, OGV showed a fluorescent ultrasensitive response for the Hg2+ and Fe3+ ions in water. Moreover, by introducing these metal ions into the OGV, stable metal ion-coordinated supramolecular metallogels (HgG and FeG) were formed, which could sense CN- and H2PO4- in water with high selectivity and sensitivity.

An easy to make chemoreceptor for the selective ratiometric fluorescent detection of cyanide in aqueous solution and in food materials

A ratiometric fluorescent receptor selectively detects cyanide in aqueous solution and food materials via deprotonation of a phenolic hydroxyl group.

Azines: synthesis, structure, electronic structure and their applications

Azines (2,3-diaza-1,3-butadienes): structure, electronic structure, tautomerism, and their applications in organic synthesis, medicinal chemistry and materials chemistry.

A new Schiff-base chemosensor for selective detection of Cu2+ and Co2+ and its copper complex for colorimetric sensing of S2- in aqueous solution

A new Schiff-base colorimetric chemosensor 1 was developed for the detection of Cu²⁺, Co²⁺ and S^2-. Sensor 1 could simply monitor Cu²⁺ and Co²⁺ by a color change from colorless to yellow. The binding modes of 1 to Cu²⁺ and Co²⁺ were determined to be a 2 : 1 complexation stoichiometry through Job's plot and ESI-mass spectrometry analysis. The detection limits (0.02 μM and 0.63 μM) for Cu²⁺ and Co²⁺ were lower than the recommended values (31.5 μM and 1.7 μM) by the World Health Organization (WHO) for Cu²⁺ and the Environmental Protection Agency (EPA) for Co²⁺, respectively. Importantly, 1 could detect and quantify Cu²⁺ in real water samples. In addition, the Cu²⁺-2·1 complex could be used as a highly selective colorimetric sensor for S^2- in the presence of other anions without any interference. Moreover, the sensing mechanisms of Cu²⁺ and Co²⁺ by 1 were explained by theoretical calculations.

A novel colorimetric and ratiometric fluorescent CN− sensor based on rhodamine B hydrazone derivatives in aqueous media and its application in sprouting potatoes

A novel cyanide specifically selective and highly sensitive chemosensor Z based on rhodamine B hydrazone derivatives had been designed and synthesized.

A cyanide-triggered hydrogen-bond-breaking deprotonation mechanism: fluorescent detection of cyanide using a thioacetohydrazone-functionalized bispillar[5]arene

Bispillar[5]arene-based fluorescent sensor was used for fluorescent detection of cyanide anions through deprotonation accompanied by intermolecular hydrogen bond breakage.