Fluorescence sensing of Cu within a pseudo 18-crown-6 cavity

We report herein a pseudo-crown based fluorescent receptor (1) for the selective detection of Cu²⁺ cation. Receptor 1 can detect Cu²⁺ even in 5 μM level in acetonitrile-water (9:1 v/v). Compound 1 is very effective for the detection of Cu²⁺ amongst the series of metal ions studied (Li⁺, Na⁺, K⁺, Ca²⁺, Mg²⁺, Ba²⁺, Pb²⁺, Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Hg²⁺ and Mn²⁺).     

Preconcentration of metal ions using an immobilized dialkyldithiocarbamate in a flow system

Flow injection analysis with on-line preconcentration using a minicolumn loaded with dialkyldithiocarbamate immobilized on controlled pore glass is described for the determination of Rh(III), Co²⁺, Cu²⁺, Hg²⁺, and Hg₂²⁺. The detection limits range from 0.05 ng ml⁻¹ for Cu²⁺ to 50 ng ml⁻¹ for Hg²⁺ for 5- or 10-ml samples, improvement of 2–3 orders of magnitude compared with direct injection. The operating conditions are optimized and the effects of interferents are studied. The capacity of the collector varied from 0.9 mmol g⁻¹ for Rh(III) to ca 4 mmol g⁻¹ (Co²⁺, Cu²⁺, Hg²⁺).     

Synthesis of a Dithiocarbamate Chelate Resin and Its Oxidized form and Their Adsorption Properties for Heavy Metal Ions

A series of macroporous dithiocarbamate chelate resins, III and V, and an oxidized resin, VI, with high adsorption capacity were prepared. The influence of various reaction conditions of amination, dithiocarboxylation, and oxidation were examined. The structure and the conversion of functional groups of resins were confirmed by IR spectra and elemental analysis. The adsorption capacities of Resin II for Hg²⁺, Cu²⁺, Zn²⁺, and Cd²⁺ are 4.40, 2.44, 1.77, and 1.36 mmol/g, respectively. The adsorption capacities of Resins V and VI for Cu²⁺. Zn²⁺, Ni²⁺, Co³⁺, Ag⁺, Hg²⁺, Cd²⁺, Pb²⁺, and Au³⁺ are 4.07–0.51 and 3.81–0.59 meq ion/g, respectively. The adsorption rate and the influence of pH on the adsorption percentage of the resins for metal ions were examined. Noble metal, transitional metal, and heavy metal ions can be quantitatively adsorbed by the resins. The adsorbed Cu²⁺, Pb²⁺, Cd²⁺, Co³⁺, and Ni²⁺ can be quantitatively eluted with 5N HNO₃, and the presence of large amounts of Ca²⁺, Mg²⁺, Fe³⁺, and Al³⁺ did not interfere.     

Design and synthesis of a new fluorescent tripod for chemosensor applications

A new yellow-green fluorescent tripod based 1,8-naphthalimide has been synthesized and characterised. Its photophysical properties have been investigated in organic solvents of different polarity. The effect that the metal ions (Cd²⁺, Co²⁺, Zn²⁺, Mn²⁺, Mg²⁺, Ni²⁺, Pb²⁺, Cu²⁺, Ba²⁺, Fe³⁺ and Ag⁺) produce upon the fluorescent intensity of acetonitrile solutions of the tripod has been discussed viewing its potential applications as a detector for metal cations. The influence of protons on the fluorescence intensity of the tripod in DMF and methanol–water (1:4 v/v) solutions has also been investigated.     

Chemical properties of N-2-Sulfoethylchitosan with a medium degree of substitution

A method was developed for the preparation of N-2-sulfoethylchitosan (SECH) via synthesis in a gel with the use of the reaction of chitosan and sodium 2-bromoethanesulfonate. This method makes it possible to conduct a polymer-like transformation without any acid or base. The structures of the obtained polymers were confirmed via IR and ¹H NMR spectroscopy. The study of the sorption of Ag⁺, Cu²⁺, Zn²⁺, Ni²⁺, Co²⁺, Cd²⁺, Pb²⁺, Mn²⁺, Mg²⁺, Ca²⁺, Sr²⁺, and Ba²⁺ ions that were crosslinked by SECH during their joint presence in an ammonia-acetate buffer solution showed high values of selectivity in relation to those of silver(I) and copper(II). The selectivity of the sorption of silver(I) ions with respect to copper(II) ions increased with an increase in the degree of substitution of SECH.     

Synthesis of a new pyrene-devived fluorescent probe for the detection of Zn2+

A novel pyrene-based receptor bearing benzothiazole was synthesized as a good turn-on fluorescent sensor for the recognition of Zn²⁺. The probe showed an excellent selectivity for Zn²⁺over most other competing ions (eg, Cr³⁺, Li⁺, Cd²⁺, Al³⁺, Pb²⁺, Li⁺, Mg²⁺, Ag⁺, Ca²⁺, Ni²⁺, Mn²⁺, Fe³⁺, Hg²⁺, Ba²⁺, K⁺, Na⁺, Cu²⁺, Fe²⁺) in EtOH-HEPES (65:35, v/v, pH?=?7.20), which might be attributed to the photoinduced electron transfer (PET) mechanism. The formation of 1:1 stoichiometric PBZ-Zn²⁺ complex was determined based on the Job's plot, ¹H NMR titration and ESI-MS. The binding constant of the complex was 4.04?×?10⁴?M^?1 with a detection limit of 2.58?×?10^?7?M. The potential application of the PBZ in real water samples for recognizing Zn²⁺ was investigated. Bio-imaging study also revealed that PBZ could be applied to detecting Zn²⁺ in live cells. These results indicated that PBZ could be a favorable probe for Zn²⁺.     

The Design of a Highly Selective Fluorescent Chemosensor for Cu(II) within Wide pH Region and a Molecular Switch Controlled by pH

A new calix[4]arene-based fluorescent compound with two thio-ether groups as ionophore and one 3-alkoxy-2-naphthoic acid moiety as fluorophore has been designed, which exhibited highly selective binding of Cu ²⁺ over alkali, alkaline earth and some transition metal ions, including Co ²⁺, Ni ²⁺, Zn ²⁺, Mn ²⁺, Cd ²⁺, Pb ²⁺, Hg ²⁺, Ag ⁺, Cu ⁺, in CH ₃OH–H ₂O (2:1) within wide pH region. Moreover, the change of pH induces the consecutive quenching/revival of the fluorescence, with a concomitant distinct difference of the fluorescence quantum yield. In consequence, this system could be considered as a molecular switch.     

Response characteristics of a potentiometric detector with a copper metal electrode for flow-injection and chromatographic determinations of metal ions

The potentiometric response characteristics of a copper metal indicator electrode are reported in a flow-injection system when metal ions are injected into ligands of differing complexing strengths in buffered carrier streams. Theoretical Nernstian derivation of equations relating peak heights to both the injected metal ion concentration and the ligand concentration are shown to give good agreement with experimental peak height measurements for Ca²⁺, Al³⁺, Pb²⁺, Cd²⁺, Co²⁺, Cu²⁺, Ni²⁺, Mn²⁺, Zn²⁺ and UO²⁺₂. A study of injections into buffered ligand streams containing EDTA, ethylenediamine, triethylenetetramine, iminodiacetate, citrate, or glutamate shows advantages for the use of the more weakly complexing ligands in the carrier stream. Linear response are obtained at low (10^?3–10^?4 M) metal ion concentrations over narrow ranges. Some chromatographic applications are outlined.     

Studies on bismuth tungstate and its use as a lead selective inorganic ion-exchanger

Summary A new inorganic ion-exchanger bismuth tungstate has been synthesized. Its composition, chemical stability and ion-exchange properties have been studied. The material shows high selectivity towards Pb²⁺, which has been separated quantitatively from Zn²⁺, Mg²⁺, Ca²⁺, Mn²⁺, Cu²⁺ and Ni²⁺. It also shows electron exchange behaviour with some strong reducing agents.     

Complexation of metal ions with the novel 2-hydroxy-1-naphthaldehyde-derived diamine Schiff base carrying a macrobicyclic moiety with N2O2S2 mixed donor in acetonitrile-dichloromethane

A new Schiff base containing a macrobicyclic moiety was designed and synthesized by reaction of the corresponding macrobicyclic diamine compound and 2-hydroxy-1-naphthaldehyde. The influence of metal cations such as Zn²⁺, Mn²⁺, Fe²⁺, Fe³⁺, Co²⁺, Ni²⁺ and Pb²⁺ on the spectroscopic properties of the 2-hydroxy-1-naphtyl group linked to the macrobicyclic moiety with N₂O₂S₂ mixed donor was investigated in acetonitrile-dichloromethane solution (9.5/0.5) by means of absorption and emission spectrometry. Emission spectra undergo a marked blue shift and enhancement of naphtyl fluorescence in the presence of Fe³⁺ and Zn²⁺. The presence of Pb²⁺, Mn²⁺, Fe²⁺, Co²⁺ and Ni²⁺ caused a quenching of naphtyl fluorescence. Especially, the quenching was higher than 90% in case of the interaction of Ni²⁺ and Co²⁺ with the ligand. The results of spectrophotometric and spectrofluorimetric titration experiments disclosed the complexation properties of the novel ligand with Zn²⁺, Co²⁺ and Ni²⁺ cations.     

Quantitative chemical analysis on paper: Micro-determination of copper and a mixture of copper and silver

Summary A method has been suggested for the determination of small amounts of copper and of mixtures of copper and silver using filter paper impregnated with silver chloride and sodium carbonate. The method depends on competition between copper and silver ions to form complexes with cyanide added to the paper. The area of the spot produced by conversion of AgCl into Ag(CN)₂ ^– is measured by weight, and is inversely proportional to the amount of copper present, since the Cu(CN)₄ ^3– complex is preferentially formed. The silver present is determined separately, and the amount of copper calculated.The determination is possible in the presence of Bi³⁺, C³⁺, Mn²⁺, Pb²⁺, K⁺, Na⁺, Ca²⁺, Sr²⁺, Ba²⁺, Mg²⁺, NH₄ ⁺, Al³⁺, Sn²⁺, Hg²⁺, Ag⁺, Fe²⁺, Fe³⁺, NO₃ ^–, SO₄ ^2–, CO₃ ^2–, CrO₄ ^2–, Cl^–, Br^–, and SCN^–.The determination is impossible in the presence of I^–, I₂, Zn²⁺, Cd²⁺, Hg₂ ²⁺, Co²⁺, or Ni²⁺.The method permits the determination of 4–30g of copper and 8–60g of silver with an accuracy of 2%.

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Zusammenfassung Eine Methode zur Bestimmung kleiner Kupfermengen und von Kupfer-Silber-Gemischen mit Hilfe von Filtrierpapier wird vorgeschlagen, das mit Silberchlorid und Natriumcarbonat imprägniert ist. Sie beruht auf der Konkurrenz zwischen Kupfer und Silber bei der Komplexbildung mit Cyanid, das man auf das Papier aufbringt. Das Flächenausmaß des durch Komplexierung des Silbers gebildeten Fleckens wird gravimetrisch bestimmt. Es ist umgekehrt proportional zur Menge anwesenden Kupfers, da [Cu(CN)₄]^3– bevorzugt gebildet wird. Das Silber wird getrennt bestimmt und so die Kupfermenge berechnet.Die Bestimmung ist möglich in Gegenwart von Bi³⁺, Cr³⁺, Mn²⁺, Pb²⁺, K⁺, Na⁺, Ca²⁺, Sr²⁺, Ba²⁺, Mg²⁺, NH₄ ⁺, A1³⁺, Sn²⁺, Hg²⁺, Ag⁺, Fe²⁺, Fe³⁺, NO₃ ^–, SO₄ ^2–, CO₃ ^2–, CrO₄ ^2–, Cl^–, Br^– und SCN^– und nicht möglich in Gegenwart von J^–, J₂, Zn²⁺, Cd²⁺, Hg₂ ²⁺, Co²⁺ oder Ni²⁺.4 bis 30g Kupfer sowie 8 bis 60g Silber können mit einer Genauigkeit von 2% bestimmt werden.

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Résumé On propose une méthode pour doser de petites quantités de cuivre et de mélanges de cuivre et d'argent, à l'aide de papier-filtre imprégné de chlorure d'argent et de carbonate de sodium. La méthode dépend de l'effet compétitif entre les ions cuivre et argent pour former les complexes avec le cyanure déposé sur le papier. La surface de la tache formée en transformant le chlorure d'argent en Ag(CN)₂ ^– est mesurée par pesée et est inversement proportionnelle à la quantité de cuivre présent, puisque le complexe Cu(CN)₄ ^3– se forme préférentiellement. L'argent présent est dosé séparément et la quantité de cuivre s'en déduit par calcul.Le dosage est possible en présence de Bi³⁺, Cr³⁺, Mn²⁺, Pb²⁺, K⁺, Na⁺, Ca²⁺, Sr²⁺, Ba²⁺, Mg²⁺, NH₄ ⁺, Al³⁺, Sc³⁺, Hg²⁺, Ag⁺, Fe²⁺, Fe³⁺, NO₃ ^–, SO₄ ^2–, CO₃ ^2–, CrO₄ ^2–, Cl^–, Br^– et SCN^–.Le dosage est impossible en présence de I^–, I₂ ^–, Zn²⁺, Cd²⁺, Hg²⁺, Co²⁺ ou Ni²⁺. La méthode permet le dosage de 4 à 30g de cuivre et de 8 à 60g d'argent avec une précision de 2%.

     

Photoactive chemosensors 4: a Cu protein cavity mimicking fluorescent chemosensor for selective Cu recognition

Fluorescent chemosensor 3 can sense Cu²⁺ ions (1-8 μM) even in the presence of elevated levels of Ni²⁺, Cd²⁺, Zn²⁺, Hg²⁺, Ag⁺ and Pb²⁺ (5000 μM). 3 can also analyze for Ag⁺ ions (50-500 μM) in the presence of Ni²⁺, Cd²⁺, Zn²⁺, Hg²⁺ and Pb²⁺ (5000 μM) but Cu²⁺ strongly interferes.     

Interaction of a Schiff-base fluorescent sensor with Al3+: experimental and computational studies

A fluorescent Al³⁺ chemo-sensor, 1-phenyl-3-methyl-5-hydroxypyrazole-4-acetone-(3′,4′-dimethylpyrrole-2′-formyl) hydrazone (L), has been synthesized and characterized. L can detect Al³⁺ in ethanol solution with a significant fluorescence enhancement of a turn-on ratio over 155-fold due to the formation of a 1?:?1 complex which is based on the molar ratio between L and Al³⁺ ions, and the 1?:?1 stoichiometric complexation can be obtained from density functional theory calculations. No significant interference of other metal ions such as Na⁺, K⁺, Mg²⁺, Ca²⁺, Ni²⁺, Zn²⁺, Cd²⁺, Co²⁺, Cu²⁺, Fe³⁺, Cr³⁺, Pb²⁺, and Ag⁺ was found. The detection limit for Al³⁺ was 5?×?10^?9?M in ethanol.     

DDB liver drug as a novel ionophore for potentiometric barium (II) membrane sensor

Dimethyl-4,4-dimethoxy-5,6,5′,6′-dimethylene dioxy biphenyl-2,2-dicarboxylate (DDB) liver drug is used as a novel ionophore in plasticized poly (vinyl chloride) (PVC) matrix membrane sensors for barium ions. Optimum performance characteristics are displayed by membrane sensor incorporating DDB ionophore, potassium tetrakis(4-chlorophenyl)borate as lipophilic salt, and o-nitrophenyloctyl ether as plasticizer. The sensor exhibits a linear response over the concentration range 10⁻¹-10⁻⁵ mol l⁻¹ BaCl₂ with a Nernstian slope of 30 mV per decade and high selectivity towards Ba²⁺ with respect to Li⁺, Na⁺, K⁺, Rb⁺, NH₄⁺, Mg²⁺, Ca²⁺, Sr²⁺, Mn²⁺, Co²⁺, Ni²⁺, Cd²⁺, Al³⁺, La³⁺, and Ce³⁺ ions. The sensor response is stable over a wide pH range (4-9) and the lifetime is about 2 months. The proposed sensor is successfully applied to the determination of Ba²⁺contents of some rocks.     

Complexation Studies of a Calix[4](aza)crown and Crystal Structure of its Magnesium Complex

A systematic study of extraction properties and complexation behaviour of the calix[4](aza)crown 1 towards alkaline earth (Mg²⁺, Ca²⁺,Sr²⁺, Ba²⁺) and transition metal (Co²⁺, Ni²⁺, Cu²⁺,Zn²⁺) cations is presented. The binding behaviour of 1 was also investigated by ¹H-NMR and the crystal structure of the 1:1 complex with Mg²⁺ isdescribed.     

A highly selective colorimetric sensor for Hg2+ based on a copper (II) complex of thiosemicarbazone in aqueous solutions

By applying an indirect strategy, a new copper (Ⅱ) complex of a thiosemicarbazone L has been successfully developed as a colorimetric chemosensor for the sensitive detection of mercury (Ⅱ) ions. In the presence of copper (Ⅱ) ions, the colorless solution of L became yellow; however, upon the addition of traces of mercury (Ⅱ) ions, the yellow color faded to colorless immediately. Other ions, including Fe3+ , Ag+ , Ca2+ , Zn2+ , Pb2+ , Cd2+ , Ni2+ , Co2+ , Cr3+ and Mg2+ had a negligible influence on the probe behavior. The detection limits were 5.0×10 -6 M and 3.0×10 -7 M of Hg2+ using the visual color changes and UV-vis changes respectively. Test strips based on Cu-L were fabricated, which could act as a convenient and efficient Hg2+ test kits.     

A Simple Fluorometric Method Using Chlorophyll a for Determination of Hg2+ Ion

A simple and green analytical procedure based on chlorophyll a is presented for the determination of Hg²⁺ ion. Chlorophyll a was extracted and purified from the leaves of pea and is employed as a reagent for analysis of Hg²⁺ ion. It displays remarkable fluorescence emission at 674 nm when excited at 412 nm. The emission intensity decreased significantly on exposure to various concentrations of Hg²⁺ ion. This forms the basis for the determination of Hg²⁺ ion. The proposed method was evaluated for sensitivity and selectivity. The linear concentration range was found to be 2.0–10 μM with r² = 0.997 and the limit of detection for Hg²⁺ ion was 1.3 μM. Ions including Pb²⁺, Cd²⁺, Ag⁺, Zn²⁺, Co²⁺, Ni²⁺, Cu²⁺, Mg²⁺, Mn²⁺, Ru³⁺, Er³⁺, K⁺, Na⁺, NH₄⁺, Cl⁻, NO₃⁻, CH₃COO⁻ and SO₄²⁻ did not interfere with the measurement of Hg²⁺ ion even at 500-fold excess. Since chlorophyll a is widely available in the leaves of most plants, and the extraction and purification process is simple, this technique can provide an alternative, sensitive and economical way to determine Hg²⁺ ion.     

Synthesis of a novel poly(para‐phenylene ethynylene) for highly selective and sensitive sensing mercury (II) ions

A new poly(p‐phenylene ethynylene) derivative with pendant 2,2′‐bipyridyl groups and glycol units (PPE‐bipy) has been prepared, and its metal ion sensing properties were investigated. The polymer of PPE‐bipy exhibited high selectivity for Hg²⁺ as compared with Li⁺, Na⁺, K⁺, Ba²⁺, Ca²⁺, Mg²⁺, Al³⁺, Mn²⁺, Ag⁺, Zn²⁺, Pb²⁺, Ni²⁺, Cd²⁺, Cu²⁺, Co,²⁺ and Fe³⁺ in THF/EtOH (1:1, v/v) solution. The fluorescence of PPE‐bipy was efficiently quenched by Hg²⁺ ions, and the detection limit was found to be 8.0 nM in a THF/EtOH (1:1, v/v) solvent system. PPE‐bipy also showed a selective chromogenic behavior toward Hg²⁺ ions by changing the color of the solution from slight yellow to colorless, which can be detected with the naked eye. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1998–2007, 2008     

Homogeneous Chemiluminescent Determination of Mercury(II) Using a Peroxidase-Mimicking DNAzyme Assay

Environmental pollution in manufacturing sectors is often accompanied by the release of diverse forms of pollutants including heavy metals. Mercury is one of the most toxic heavy metals. Here, we describe a homogeneous chemiluminescent method for Hg²⁺ detection based on allosteric activation of peroxidase-mimicking DNAzyme and formation of Hg²⁺-thymine bonds in DNA duplex with T–T mismatches in the presence of mercury. The formation of such duplex increased the activity of peroxidase-mimicking DNAzyme. The analysis conditions and structures of probes were optimized. Under the favorable conditions, the limit of detection and a linear range of the assay were 12 and 12–600?nM, respectively. The values of coefficient of variation measured within the working range varied from 0.7 to 3.0%. The study of cross-reactivity of Hg²⁺, Ag⁺, Pb²⁺, Ca²⁺, Zn²⁺, Bi³⁺, Ni²⁺, Co²⁺, Ba²⁺, Mn²⁺, Cd²⁺, Mg²⁺, and Cr³⁺ showed that only mercury in concentration nanoscale activates peroxidase-mimicking DNAzyme that indicates high specificity of the developed Hg²⁺ assay. Thus, an easy-to-use, specific, rapid, and sensitive method for Hg²⁺ detection was developed.     

Fluorescence quenching studies on the interaction of a novel deepened cavitand towards some transition metal ions

A novel ‘three-level’ deepened cavitand featuring a significantly sizable portal has been synthesized and its interaction with some transition metal ions has been investigated in THF/H₂O binary solvent using fluorescence quenching technique. The results suggest that among the used transition metal ions including Ag⁺, Cd²⁺, Cu²⁺, Fe³⁺, Cr³⁺, Hg²⁺, La³⁺, Mn²⁺, Ni²⁺, Zn²⁺ and Co²⁺, only Fe³⁺ and Cu²⁺ show good quenching ability. In order to interpret the quenching mechanism, the Stern–Volmer kinetics, and the presence of both the dynamic and static quenching have been discussed. It was found that the simultaneous presence of the sphere-of-action static quenching and dynamic quenching model agrees very well with the experimental results. The limits of detection for Fe³⁺ and Cu²⁺ were found to be 2.1 × 10⁻⁶ mol L⁻¹ (3σ) and 3.6 × 10⁻⁶ mol L⁻¹ (3σ), respectively. Cations with potential interference, such as K⁺, Na⁺, Mg²⁺, Ca²⁺, Co²⁺, La³⁺ and Mn²⁺ do not have significant effects on the determinations of Fe³⁺ and Cu²⁺. This cavitand can be potentially applied as optical sensor for the detection of Fe³⁺ and Cu²⁺.