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1.
The adsorption of copper species on a positively charged hanging mercury drop electrode in complexing ligand/surfactant/chloride solution is discussed. Techniques used were differential pulse voltammetry of the copper in the adsorbed film, and potential-step reduction of adsorbed copper followed by different pulse anodic stripping voltammetry of Cu(Hg). The CuCl?2 species is shown to be the most important copper moiety adsorbed on the electrode and the adsorption is enhanced by organic films. This can be a critical pathway in the reduction of copper(II) in estuarine waters. The induced adsorption of copper in organic layers has biogeochemical implications associated with the nature of organic films and their influence on the Cu(II)/Cu(I) redox couple. There are also analytical applications, e.g., the compositional assay of organic monolayers by utilising Cu(II) and Cu(I) adsorption as electoractive probes and the determination of solution copper-organic binding.  相似文献   

2.
Feng L  Zhang Y  Wen L  Shen Z  Guan Y 《Talanta》2011,84(3):913-917
A simple and sensitive colorimetric method for the determination of trace copper(II) ions in aqueous solution has been developed using diphenylcarbazide (DPC) immobilized sol-gel matrices. To enhance the odds of chelating interactions between copper(II) ions and DPC, a peristaltic pump was utilized to drive copper(II) ions solution pass through the cellulose acetate/nitrate membrane, which was coated with DPC immobilized sol-gel matrices. The membrane was sandwiched in a home-made flow cell. The porous silica matrix serves as a preconcentrator, and enriches the trace copper(II) ions. Meanwhile, the filtration increases the chelating interaction probability between copper(II) ions and DPC, thereby improves the sensitivity significantly. After the formation of purple complex compound, the color changes of the DPC immobilized sol-gel membrane were recorded using a flatbed scanner. The images were digitized, and the red (R), green (G), and blue (B) values were investigated. The colorimetric method provides a rapid and reliable determination of trace copper(II) ions with a detection limit as low as 0.16 μM and a kinetic range up to 1.6 μM in neutral medium. Moreover, the method shows good selectivity, and the color changes of the DPC immobilized sol-gel membranes are remarkable for the copper(II) ions detection even in the presence of other metal ions.  相似文献   

3.
A study on the extraction of copper(II), cobalt(II), and nickel(II) from solutions containing ions of both metals with N-salicylideneaniline(SAN) in chloroform has been realized. Distribution of the metal ions in wide range of pH has been studied. Extraction of copper(II) was always favored over that of cobalt(II). Extraction of copper(II) from binary metal solution is selective and it can be quantitatively separated from cobalt(II). The equilibrium constant of the extraction of cobalt and nickel from an aqueous solution containing both metals using SAN were evaluated. The separation factors for cobalt and nickel were expressed as a function of the distribution of nickel and cobalt. From these results, salicylideneaniline is an adequate extractant for extractive separation of such mixtures.  相似文献   

4.
The electrochemical polymerisation of pyrrole-substituted cobalt tetraphenylporphine complex on a vitreous carbon electrode has been performed in acetonitrile+tetrabutylammonium tetrafluoroborate solution. The redox properties of the film have been examined by cyclic voltammetry and compared to those of cobalt-porphyrin monomer in solution. Voltammograms of these films exhibit a reversible process for the Co(II)/Co(I) reaction at a formal potential of −0.87 V/SCE. The cobalt-porphyrin content of the films has been estimated by cyclic voltammetry, and the conductivity of the polymers has been assessed by studying well-known electrochemical processes in solution at these modified electrodes. Thus, it appears that thick polyporphyrin films act as insulators in low potential range E < −1 V/SCE. Copolymerisation of the pyrrole-substituted cobalt porphyrin with pyrrole and 3-(pyrrol-1-ylmethyl)pyridine has been achieved. No improvement of the electrochemical properties has been noted for the copolymers obtained. We have also proved that interchain complexation reaction of the cobalt(III) sites occurs by the pyridine moieties of the copolymer films.  相似文献   

5.
The structure of the crystalline azamacrocyclic product formed by reaction of bis(propane-1,3-diamine)copper(II) perchlorate with acetone has been determined as N-rac-(6,8,8,14,16,16-hexamethyl-1,5,9,13-tetraazacyclohexadeca-5,13-diene)copper(II) · N-meso-(6,8,8,14,14,16-hexamethyl-1,5,9,13-tetraazacyclohexadeca-5,16(1)-diene)copper(II) perchlorate, with the cis, 5,16(1)-diene, and trans, 5,13-diene, isomeric cations co-crystallised. The structures of three compounds crystallised from solutions of this mixture have been determined. N-rac-(6,8,8,14,14,16-hexamethyl-1,5,9,13-tetraazacyclohexadeca-5,16(1)-diene)copper(II) tetrachlorozincate has an irregular flattened tetrahedral coordination geometry with trans-N-Cu-N angles of 139.27(8)° and 155.94(8)°. (Hexamethyl-1,5,9,13-tetraazacyclohexadecadiene)(thiocyanato-N)copper(II) perchlorate has twofold symmetrical square-pyramidal cations. A (μ-cyano)-tetracyanonickelate(II) compound has two (hexamethyl-1,5,9,13-tetraazacyclohexadecadiene)copper(II) cations each with a single axially coordinated tetracyanonickelate(II) group. The compounds, except for the tetrachlorozincate(II) salt, show disorder in the location of the imine functions and axial methyl substituents, attributed to co-crystallisation of enantiomers for the N-rac-trans isomer and/or of rotated arrangements of the N-meso-cis isomer. For the thiocyanato and tetracyanonickelato compounds this disorder precluded unambiguous assignment of configuration.  相似文献   

6.
Polyimide films based on either 3, 3′, 4, 4′-benzophenone tetracarboxylic acid dianhydride or pyromellitic dianhydride with 4,4′-oxydianiline have been doped with copper(I) and copper(II) complexes. High-quality, flexible, glass-cast films have been obtained which exhibit increased softening temperatures and lower polymer decomposition temperatures. The atmosphere and glass sides of the films are quite different. The copper(I) dopant is oxidized on the air side of the film, while the glass side contains predominantly copper (I). In the copper(II) case most of the copper appears on the air side as a silvery substance in the Cu(II) state. Chemical as well as ion etching can remove this material. Electrical resistivity of the copper(II)-doped films is decreased by three to five orders of magnitude relative to the polymer alone.  相似文献   

7.
A novel method for indirect determination of ampicillin sodium by the extraction-flotation is proposed in this paper. It is indicated that the degradation of ampicillin sodium took place in the presence of 0.30 M sodium hydroxide in boiling water for 20 min. At pH 4.0, in the presence of ammonium thiocyanate, the thiol group of the degradation product of ampicillin sodium could reduce copper(II) to copper(I) due to the formation of the emulsion cuprous thiocyanate precipitation. By determining the residual amount of copper(II) in the solution and calculating the flotation yield of cuprous thiocyanate, the indirect determination of ampicillin sodium can be performed. When the concentration of cooper(II) was 5.0 μg/mL, a good linear relationship was obtained between the flotation yield of cuprous thiocyanate and the amount of ampicillin sodium in the range of 0.40~9.6 μg/mL. The linear equation is E = 4.1469 + 3.7949c with the correlation coefficient r = 0.9992, and the detection limit (3σ/K) of 0.37 μg/mL. Each parameter has been optimized and the reaction mechanism has been studied. The method has been successfully applied to the determination of ampicillin sodium in pharmaceutical, human plasma and urine samples. Analytical results obtained are satisfactory.  相似文献   

8.
A disposable sensor has been developed for the measurement of copper(II) concentration in aqueous solution based on a change in the fluorescence of porphyrazine 2,7,12,17-tetra-tert-butyl-5,10,15,20-tetraaza-21H,23H-porphine (TP). The sensor was constructed by spin-coating a polyester support with a PVC solution containing TP, a plasticizer, the chelating agent Zincon and the ion-pairing benzetonium chloride. The measurement principle is based on the radiationless resonance energy transfer (RET) from TP immobilized in membrane, and acting as fluorescence donor, to Zincon acting as an acceptor induced by copper(II). The absorption spectrum of the Zincon-Cu(II) complex presents adequate overlapping with the emission spectrum of TP, producing a useful analytical signal by the RET process.The disposable sensor responds to copper(II) irreversibly over a dynamic range from 0.039 to 14 μmol L−1 (2.5-890 μg L−1) with a sensor-to-sensor reproducibility (relative standard deviation RSD) of 1.9%, as log aCu2+, at the medium level of the range and a response time of 10 min. The performance of the optical disposable sensor was tested for the analysis of copper in different types of natural waters (river, well, spring and swimming pool), validating results against a reference procedure.  相似文献   

9.
The new synthesized thiomacrocyclic ionophore 4-phenyl-4-sulfide-11-(1-oxodecyl)-1,7-dithia-11-aza-4-phosphacyclotetradecane has proven to form Langmuir and Langmuir-Blodgett (LB) films. This ionophore shows a large affinity for copper(II) ions. Thus, the influence of the subphase composition on the surface pressure-area isotherms has been studied. The LB films have been observed by AFM and the effect of the subphase composition and the deposition surface pressure on the LB films is discussed. AFM image morphology has been correlated to the ionophore molecular structure. Surface pressure-area isotherms and AFM images show that the presence of copper(II) ions has an important role in the film structure.  相似文献   

10.
The synthesis of four N-benzoylthioureas containing pyrrole groups are described. The electrochemical behaviour of their copper(II) and nickel(II) complexes has been investigated in aprotic solvents by coulometry and by cyclic voltammetry which indicates that the electrochemical oxidation of copper complexes leads to the formation of CuII-benzylureate complexes. The oxidative polymerization of nickel complexes on platinum and a glassy carbon electrode, has been carried out in MeCN.The redox properties of the polymeric films formed have been examined by cyclic voltammetry. The films are catalytically active in the electroreduction of oxygen.  相似文献   

11.
A sequential injection analysis (SIA) using lab-on-valve with air segmentation and spectrophotometric detection was designed for copper(II) determination. It is based on the reaction of copper(II) and 2-carboxy-2′-hydroxy-5′-sulfoformazyl benzene (Zincon) in a weak alkaline solution between the air zones. Beer's Law was obeyed over the range of 0.1-2.0 mg L−1 copper(II) with a correlation coefficient 0.9985 and a slope of 0.2893 absorbance unit/mg L−1. The relative standard deviation was 2.0% for a series of 10 measurements of 0.5 mg L−1 copper(II) solution. The detection limit (3 S/N) and the limit of quantification (LOQ) were 0.05 and 0.17 mg L−1 respectively. This method has been successfully applied to determination of copper(II) in wastewater with a sample throughput of 120 h−1. The method is superior to the batchwise method in that it provides fully automation, rapidity, less reagents and sample consumption with little waste generation.  相似文献   

12.
The feasibility of a novel and simple layer-by-layer chemical deposition method for the preparation of nano-sized metal 8-hydroxyquinolate complexes has been investigated and reported. Uniform nanocrystalline films have been synthesized via dipping a substrate alternately in metal ion solution followed by ligand solution. The stoichiometry of the as-grown anhydrous Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) complex crystals were confirmed from the metal analysis and molar stoichiometric ratio of metal ion to 8-hydroxyquinoline. This was characterized as 1:2 for the Co(II), Ni(II), Cu(II) and Zn(II)–quinolate complexes. The Fe(III)–quinolate thin film was found to exhibit a 1:3 ratio. Electron impact-mass spectra (EI-MS) of all the synthesized thin film metal quinolate complexes were recorded and the results refer to the existence of the molecular ion peak at the corresponding m/z values. Confirmation of such stoichiometric 1:2 and 1:3 ratios were also evident from the (EI-MS) study. The deposited thin films were also subjected to analysis by a scanning electron microscope (SEM) and a particle size ?50 nm was detected. FT-IR and UV–Vis spectroscopy were further used to confirm the structure of the metal 8-hydroxyquinolate complexes. Thermal gravimetric analysis (TGA) was also used to follow up the possible thermal decomposition steps and to calculate the thermodynamic parameters of the nano-sized metal complexes.  相似文献   

13.
For the first time, the formation of a luminescent hexanuclear cluster has been used for the selective determination of copper. In aqueous solutions, the non-luminescent ligand N-ethyl-N′-methylsulfonylthiourea (EMT) forms an intensely red luminescent hexanuclear Cu(I)-cluster with an emission maximum at 663 nm only with Cu(II) ions. The intensity of the luminescence is proportional to the Cu(II) concentration and allows for selective Cu determinations in the μg l−1-range. Ubiquitous metal ions such as Fe(III), Al(III), Ca(II), Mg(II), and alkaline metal ions, as well as other heavy metal ions, e.g. Co(II), Ni(II), Zn(II), Cd(II), Hg(II), and Pb(II) are tolerated in concentrations up to 50 mg l−1. The detection limit for Cu(II) in aqueous solution, calculated according to Funk et al. [Qualitätssicherung in der Analytischen Chemie, Verlag Chemie, Weinheim, 1992], is 113 μg l−1. The cluster formation has been used for the quantitative analysis of copper in tap water and in industrial water, as well as for the localization of copper adsorbed by activated-sludge flocs.  相似文献   

14.
Within this research, the CrdA protein from Helicobacter pylori (HpCrdA), a putative copper-binding protein important for the survival of bacterium, was biophysically characterized in a solution, and its binding affinity toward copper was experimentally determined. Incubation of HpCrdA with Cu(II) ions favors the formation of the monomeric species in the solution. The modeled HpCrdA structure shows a conserved methionine-rich region, a potential binding site for Cu(I), as in the structures of similar copper-binding proteins, CopC and PcoC, from Pseudomonas syringae and from Escherichia coli, respectively. Within the conserved amino acid motif, HpCrdA contains two additional methionines and two glutamic acid residues (MMXEMPGMXXMXEM) in comparison to CopC and PcoC but lacks the canonical Cu(II) binding site (two His) since the sequence has no His residues. The methionine-rich site is in a flexible loop and can adopt different geometries for the two copper oxidation states. It could bind copper in both oxidation states (I and II), but with different binding affinities, micromolar was found for Cu(II), and less than nanomolar is proposed for Cu(I). Considering that CrdA is a periplasmic protein involved in chaperoning copper export and delivery in the H. pylori cell and that the affinity of the interaction corresponds to a middle or strong metal–protein interaction depending on the copper oxidation state, we conclude that the interaction also occurs in vivo and is physiologically relevant for H. pylori.  相似文献   

15.
5-Aminouracil was found to form a six-coordinate copper(II) complex in aqueous solution and undergo oxidation to 5,5,6-trihydroxypyrimidine-2,4(1H,3H)-dione in the presence of molecular oxygen. A scheme was proposed for the fixation and activation of molecular oxygen on six-coordinate copper(II) complex with 5-aminouracil. The effect of the ligand structure on the rate of its oxidation with molecular oxygen in aqueous solution in the presence of copper(II) ions was shown.  相似文献   

16.
A direct HPLC method for the determination of acetyl-D-carnitine in acetyl-L-carnitine was investigated. The enantiomers were successfully separated on a SUMICHIRAL OA-6100 column, which has a ligand-exchange type of chiral moiety. The mobile phase consisted of an aqueous solution of copper (II) sulfate and sodium perchlorate. Successful enantioseparation seems to be achieved through the formation of not only the complex with copper (II) ion but also by ion-pairing with the perchlorate ion, because no enantioseparation was observed with the usual copper (II) mobile phase alone. Employing 2 mM aqueous CuSO4 solution containing 500 mM NaClO4, the enantiomers of acetylcarnitine eluted in the order of D- and L-forms within 15 min with R s = 1.92 and α = 1.11. The obtained LOQ and LOD values were 0.15 and 0.1%, respectively. The validated results were satisfactory for a practical quality control method for the enantiomeric purity determination of acetyl-L-carnitine.  相似文献   

17.
New copper ion-selective electrodes based on chalcogenide glasses, CuxAg25?xAs37.5Se37.5, display high copper(II) ion sensitivity with Nernstian response in the range pCu 1–6, short response time, high selectivity, potential stability and reproducibility. These electrodes are 10–30 times more sensitive in strongly acidic media than crystalline copper ion-selective sensors and are superior to the copper(I) selenide electrode in selectivity and resistance to acids and oxidation. A model is proposed to explain the ion sensitivity of these chalcogenide glass sensors. The sensitivity depends on direct exchange of copper(II) ions between solution and the modified surface layer of the glass. The modified surface layer is formed as a result of partial destruction of the glass network on soaking in solution; its atomic density is 2.0–2.5 times less than that of the original glass. The structural defects and hollows make fast copper(II) ion migration within the modified surface layer possible. Exchange sites in this layer can be formed by both disproportionation and oxidation of copper(I) in the glass network, as well as by diffusion of copper(II) ion from solution in the case of glasses with low copper content. Experimental confirmation of this model is provided by x-ray, photo-electron and scanning Auger electron spectroscopy.  相似文献   

18.
Only a limited number of multinucleating ligands can stably maintain multinuclear metal structures in aqueous solutions. In this study, a water-soluble dinucleating ligand, 2,6-bis{[N-(carboxylatomethyl)-N-methyl-amino]methyl}-4-methylphenolate ((sym-cmp)3−), was prepared and its copper(II) complexes were structurally characterized. Using the single-crystal X-ray diffraction method, their dimer-of-dimers type defect cubane tetranuclear copper(II) structures were characterized for [Cu4(sym-cmp)2Cl2(H2O)2] and [Cu4(sym-cmp)2(CH3O)2(CH3OH)2]. In the complexes, each copper(II) ion has a five-coordinate square-pyramidal coordination geometry. The coordination bond character was confirmed by the density functional theory (DFT) calculation on the basis of the crystal structure, whereby we found the bonding and anti-bonding molecular orbitals. From the cryomagnetic measurement and the magnetic analysis, overall antiferromagnetic interaction was observed, and this magnetic behavior is also explained by the DFT result. Judging from the molar conductance and the electronic spectra, the bridging chlorido ligand dissociates in water, but the dinuclear copper(II) structure was found to be maintained in an aqueous solution. In conclusion, the tetranuclear copper(II) structures were crystallographically characterized, and the dinuclear copper(II) structures were found to be stabilized even in an aqueous solution.  相似文献   

19.
The transfer and separation of Cu(II), Co(II), Ni(II) and Zn(II) ions across a hollow fiber supported liquid membrane containing LIX 864 as the mobile carrier dissolved in kerosene solvent has been investigated. The flux and selectivity for copper has been studied as a function of the feed flow, the carrier concentration in the liquid membrane and the extraction solution acidity. A maximum copper recovery at 30% of LIX (v/v) in the diluent was obtained. The permeation experiments showed that at pH 2 in the extraction solution a highly selective separation of Cu over the other cations can be achieved. Increasing the acidity of the extraction solution copper selectivity decrease and the grade of recuperation sequence is Cu>Co>Ni>Zn. These results suggest that in selected situations, this membrane system can be competitive with the conventional liquid-liquid extraction process, in particular in leaching solutions with low metal concentration.  相似文献   

20.
The possibility of obtaining smooth homogeneous copper coatings with good adhesion and homogeneous copper coatings with poor adhesion by electrochemical deposition of copper on steel from a solution of nontoxic copper(II) complex with the ligands, 1,3-propylenediamine-N,N′-diacetato-N,N′-di-3-propionic acid, was analyzed. For both types of coatings, the optimum composition of the solution and the optimum deposition conditions were determined.  相似文献   

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