Cuprous Compound Research Articles

Electrochemical Reduction of Copper Complexes with Glycine, Alanine and Valine

Basic electrochemical studies of coordination complexes between cupric ions and simple amino acids as ligands (L), namely glycine, alanine and valine, have been carried out to provide insight in the effect of complexation on Cu2+ discharge electrochemistry. The results show that there are strong differences in their cyclic voltammograms, despite the similarities in coordination equilibrium, central atom d electronic structure and inner sphere coordination distances (verified by chemical equilibrium quantification, UV spectroscopy and EXAFS). Evidence of mass transport limitations by diffusion of the neutral CuL2 complexes in solution, and cuprous species generation on the electrode during copper electrodeposition was found, both of which proved to be the main phenomena accounting for the different electrochemical behaviour previously mentioned. Voltammetric studies also showed that, surprisingly, cuprous species are produced not only at the onset of copper electroreduction but at more cathodic potentials. Furthermore, results suggest the existence of a cuprous compound layer beneath the metallic copper deposit. The data gathered in this investigation, leads to the conclusion that the bigger molecular size and organic nature of the ligands induce unexpected processes on the copper electroreduction mechanism.

Effect of the kind of cupric compound deposit on thermal decomposition of anion exchangers

The effect of the inorganic deposit on the thermal decomposition of hybrid ion exchangers (HIXs) has not been comprehensively studied before. Therefore, as part of this research anion exchangers containing cupric compound in their matrix (CuO, Cu(OH)2 and Cu4(OH)6SO4) were subjected to thermal analysis. Strongly basic commercial anion exchangers, i.e. a macroreticular anion exchanger (M) and a gel-like anion exchanger (G), were used as the host materials. M, M/CuO, M/Cu(OH)2 and G, G/CuO, G/Cu4(OH)6SO4 were subjected to thermal analysis under respectively air and N2. The samples of the HIXs contained 57.8–84.5 mg Cu/g. The results of twelve experiments are discussed on the basis of the TG/DTG curves and XRD patterns for the solid residues. The effects of: (a) the process conditions, (b) the type of deposit and (c) the structure of the anion exchanger on the course of the thermal transformations, the process end temperature, the amount of carbonizate in the post-pyrolysis residue and the composition of the inorganic phase (CuO after combustion, Cu0 or Cu2S after pyrolysis) were determined. It was demonstrated that during the thermal decomposition of the HIXs under N2 the reduction of Cu(II) was taking place, and owing to this hydrogen-consuming conversion more carbonizate formed than in the pyrolysis of the pure resins, as under hydrogen deficit the hydrocarbon radicals condensed into large non-volatile particles.

Determining the Targets of Fluopsin C Action on Gram-Negative and Gram-Positive Bacteria.

The antibiotic activity of metalloantibiotic compounds has been evaluated since the 90s, and many different modes of action were characterized. In the last decade, the effects of secondary metabolites produced by Pseudomonas aeruginosa LV strain, including a cupric compound identified as Fluopsin C, were tested against many pathogenic bacteria strains, proving their high antibiotic activity. In the present study, the bactericidal mechanisms of action of Fluopsin C and the semi-purified fraction F4A were elucidated. The results found in electron microscopy [scanning electron microscopy (SEM) and transmission electronic microscopy (TEM)] demonstrated that both Fluopsin C and F4A are affecting the cytoplasmatic membrane of Gram-positive and Gram-negative bacteria. These results were confirmed by fluorescence microscopy, where these bacteria presented permeabilization of their cytoplasmatic membranes after contact with the semi-purified fraction and pure compound. Using electronic and fluorescence microscopy, along with bacterial mutant strains with marked divisional septum, the membrane was defined as the primary target of Fluopsin C in the tested bacteria.

Antimicrobial activity of anion exchangers containing cupric compounds against Enterococcus faecalis

Four hybrid ion exchangers (HIXs) containing different cupric compounds – cupric hydroxide, tenorite and brochantite – deposited within the structure of macroporous and gel-type anion exchangers were studied for their antibacterial activity. Proposed HIXs contained different amounts of the cupric load (in the range 52.0–82.0 mg/g of Cu(II)), which was differently deposited in the polymeric beads depending on the synthesis route and the porous structure of the host polymer. All studied materials, including supporting anion exchangers without the cupric deposit, exhibited antibacterial activity against Enterococcus faecalis ATCC 29212 in the following order: macroporous HIX with cupric hydroxide >> gel-type HIX with brochantite > macroporous HIX with tenorite = gel-type HIX with tenorite > macroporous anion exchanger > gel-type anion exchanger. The best macroporous hybrid polymer containing cupric hydroxide showed a massive reduction in cell survival at a dose of 64 mg. The antimicrobial activity was a synergetic effect of the presence of both components – cupric deposit and polymeric support – which was strongly affected by the developed porous structure of the hybrid material and the dispersed distribution of the cupric compound within the outer parts of the polymeric beads.

Iodide-Centered Cuprous Octatomic Ring: A Luminescent Molecular Thermometer Exhibiting Dual-Emission Character

Luminescent molecular thermometers have attracted great attention due to their potential application for temperature detection in special environments. By a very simple one-step method, we have synthesized one novel cuprous compound, [I@Cu8(HMTZ)(MTZ)7]·MeCN·2H2O (I@Cu8), which consists of an infrequent octatomic [I@Cu8S8] ring. Importantly, compound I@Cu8 features dual-emitting behavior and shows successive visual luminescent emissions varying from green, to yellow, to orange, and then to red in the temperature range of 80–300 K, suggesting potential application for a luminescent molecular thermometer.

キトサンに担持した銅(II)化合物による還元性有機化合物の検出

キトサンに担持した銅(II)化合物による還元性有機化合物の検出

Copper sulfate pentahydrate reduced epithelial cytotoxicity induced by lipopolysaccharide from enterogenic bacteria.

The over usage of multiple antibiotics contributes to the emergence of a whole range of antibiotic-resistant strains of bacteria causing enterogenic infections in poultry science. Therefore, finding an appropriate alternative natural substance carrying an antibacterial capacity would be immensely beneficial. It has been previously discovered that the different types of cupric salts, especially copper sulfate pentahydrate (CuSO4·5H2O), to carry a potent bactericidal capacity. We investigated the neutralizing effect of CuSO4·5H2O (6.25μg/ml) on the reactive oxygen species generation, and expression of MyD88, an essential adaptor protein of Toll-like receptor, and NF-κB in three intestinal epithelial cell lines exposed to 50ng/ml lipopolysaccharide. In order to find the optimal cupric sulfate concentration without enteritis-inducing toxicity, broiler chickens were initially fed with water containing 0.4, 0.5, and 1mg/l during a period of 4days. After determination of appropriate dosage, two broiler chickens and turkey flocks with enteritis were fed with cupric compound for 4days. We found that cupric sulfate can lessen the cytotoxic effect of lipopolysaccharide by reducing the reactive oxygen species content (p<0.05). Additionally, the expression of MyD88 and NF-κB was remarkably down-regulated in the presence of lipopolysaccharide and cupric sulfate. The copper sulfate in doses lower than 0.4mg/ml expressed no cytotoxic effect on the liver, kidney, and the intestinal tract while a concentration of 0.5 and 1mg/ml contributed to a moderate to severe tissue injuries. Pearson Chi-Square analysis revealed the copper cation significantly diminished the rate of mortality during 4-day feeding of broiler chicken and turkey with enteritis (p=0.000). Thus, the results briefed above all confirm the potent anti-bactericidal feature of cupric sulfate during the course of enteritis.

Synthesis, Structure, Fluorescence, and Theoretical Studies of CuCl(2,2′-Bipyridine)2·3.5H2O

A cuprous compound CuCl(2,2′-bipyridine)2·3.5H2O (1) has been prepared through a hydrothermal reaction and structurally characterized by single crystal X-ray diffraction. The crystal structure analysis revealed that compound 1 is characterized by an isolated structure, based on CuCl(2,2′-bipyridine)2 moieties and lattice water molecules. The Cu+ ion coordinates to four nitrogen ions of two 2,2′-bipyridine molecules and one terminal chloride ion. Photoluminescent study displays that compound 1 has strong and broad emission bands, in combination with the molecular orbital (MO) calculation of 1, lead us to conclude that the emissions originate from ligand-to-ligand charge transfer (LLCT) transition.

Chlorobenzene Formation from Fly Ash: Effect of Moisture, Chlorine Gas, Cupric Chloride, Urea, Ammonia, and Ammonium Sulfate

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) are formed jointly with numerous products of incomplete combustion during waste incineration. Chlorobenzenes (CBz) are often cited as surrogates or precursors of PCDD/Fs. Experiments were conducted to investigate the effect of some key parameters on CBz formation, including moisture (H2O), chlorine gas (Cl2), cupric chloride (CuCl2), urea [(NH2)2CO], ammonia (NH3), and ammonium sulfate [(NH4)2SO4]. Cl2 and CuCl2 promoted CBz formation from fly ash, increasing the chlorination degree. In addition, Cl in cupric compound was more active than chlorine atom of Cl2, and chlorine type significantly affected the chlorination process. Less CBz yield was detected after S- and N-containing compounds [(NH2)2CO, NH3, and (NH4)2SO4] were added into reactive ash. High content of moisture in gas prevented CBz synthesis and reduced chlorination. These experimental results are useful to optimize CBz emission control and realize the mechanism of the correlation between CBz and PCDD/Fs.

Interaction of cupric ferrite, copper matte and slag at 1573 K

Cupric ferrite compound formed during dead roasting of copper matte can be recovered in the smelting process by reacting with the FeS contained in the matte according to the reaction 2CuO·Fe2O3 + 2FeS(matte) + 3SiO2 = Cu2S(matte) + 3(2FeO·SiO2) (slag) + SO2(g), The effects of the slag/matte ratio, reaction time and silica content have been studied in a laboratory under conditions similar to industrial practice. Experimental result shows that the copper from cupric ferrite is transferred to the matte, increasing its grade, while the iron is transferred to the slag phase.

Nature and role of active states of Pd and Cu in the oxidative carbonylation of phenols with Pd/C and cuprous oxide

Active states of palladium and copper for the oxidative carbonylation of phenol and bisphenol-A were investigated using X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) for Pd and Cu K-edges. The initial states of Pd and Cu were carbon-supported metallic Pd and cuprous oxide, respectively. During oxidative carbonylation, however, the metallic character of palladium was enhanced, as indicated by Pd K-edge XANES spectra taken before and after the reaction. Furthermore, PdPd coordination number increased from ca. 6.0 to 11.0, as determined by the quantitative EXAFS analyses of Pd K-edge. The initial crystalline cuprous oxide was converted by reaction with Bu 4NBr into an unusual linear cuprous dibromide complex stabilized by tetrabutylammonium cation. Qualitative XANES and EXAFS analyses of Cu K-edge identified the structural and electronic configuration of the cuprous complex that was found to be the active main catalyst. There was a direct correlation between the formation of the cuprous complex and the catalytic activity and selectivity. Based on these results, a possible catalytic reaction scheme was proposed for the oxidative carbonylation of phenols with the catalytic system of Pd/C, an inorganic cuprous compound and Bu 4NBr.

Uptake of Iodide by a Mixture of Metallic Copper and Cupric Compounds

Environmental contaminants harmful to the health of present and future generations involve nuclear fission products as iodine radioisotopes. {sup 129}I is potentially one of the more mobile products because of its long half-life and its tendency to go into solution as an anion that is not retarded with silicate minerals. Ability of copper/cupric compound mixtures to remove iodide from solution was investigated to predict sorption of radioactive iodine in the environment and to assess their use in a nuclear reprocessing method. Thermodynamic calculations were performed to study the stability of such mixtures in solution and to obtain equilibrium constants of Cu(0)/Cu(II)/I{sup {minus}} and Cu(0)/Cu(II)/Cl{sup {minus}} systems. Both calculations and experimental results showed that a Cu(0)/Cu{sub 3}(OH){sub 2}(CO{sub 3}){sub 2} (azurite) mixture selectively uptakes iodide ions (initial concentrations: 10{sup {minus}2} and 10{sup {minus}1} M) in the presence of 10{sup {minus}1} M chloride ions. Reaction of iodide with copper powder and azurite crystal or copper plate and azurite powder have also been investigated, leading to precipitation of CuI onto massive copper phase. The different solids were separately analyzed by XPS and MEB-EDX, giving some insight in the uptake mechanism. It is proposed that soluble copper released by the cupric compound is reducedmore » at the surface of metallic copper, leading to a preferential precipitation of CuI on copper surface.« less

Photodriven Electron and Energy Transfer from Copper Phenanthroline Excited States.

Electron and energy transfer from copper 1,10-phenanthroline excited states is observed at room temperature in organic solvents. The copper phenanthroline excited states are metal-to-ligand charge-transfer in nature and have lifetimes of approximately 70-250 ns in dichloromethane solution if methyl or phenyl substituents are placed in the 2- and 9-positions of the phenanthroline ligand. The unsubstituted cuprous compound Cu(phen)(2)(PF(6)) is nonemissive under these conditions, and the excited state lifetime is <20 ns. The rate and efficiency of energy transfer to anthracene or electron transfer to viologens is reported. The cage escape efficiency of [Cu(dpp)(2)(2+), MV(+)(*)], where dpp is 2,9-diphenyl-1,10-phenanthroline, is close to unity within experimental error. Back electron transfer to ground state products occurs at the diffusion limit, 2 x 10(10) M(-)(1) s(-)(1).

The effect of alkaline nitrobenzene oxidation conditions on the yield and components of phenolic monomers in wheat straw lignin and compared to cupric(II) oxidation

A comparative study of degradation of wheat straw lignin by alkaline nitrobenzene and cupric compound (CuO, Cu(OH) 2, CuSO 4 5H 2O) oxidation was carried out at 170 °C for 2.5 h in 2 N NaOH (7 ml) and 6.8% nitrobenzene. The major products of such a degradation were the phenolic aldehydes of vanillin and syringaldehyde in both of the reactions. A relative high guaiacyl syringyl ratio value was obtained by nitrobenzene oxidation, whereas a slightly high syringyl guaiacyl ratio appeared in the cupric(II) oxidation. A suite of up to 13 phenols was detected in the oxidation mixtures except that no acetosyringone appeared in the nitrobenzene oxidation. Gallic acid, protocatechuic acid and acetovanillone were firstly identified in both of the oxidation products from wheat straw lignin. The main difference between the two oxidant reagents was twice yield of nitrobenzene oxidation than that of cupric(II) oxidation. The effects reaction time, temperature, concentration of sodium hydroxide and nitrobenzene, and the amounts of sample used on the reaction yield and components of oxidation products from wheat straw were performed at 38 various conditions and the nature of the aldehyde and acid products determined by high-performance liquid chromatography (HPLC). The results obtained showed that the percentages of various products were dependent on the conditions of alkaline nitrobenzene oxidation. The reaction condition (0.10 g straw in 2 N NaOH (7 ml) with 6.8% nitrobenzene at 170 °C for 4 h in a steel autoclaves) optimised for maximum recovery of products from wheat straw. Meanwhile, ferulic and p-coumaric acid released in amounts during the nitrobenzene oxidation, especially, at 170 °C for 2.5 h in 2 N NaOH without nitrobenzene, which suggested that more than 50% of ferulic acid was in the etherified form while p-coumaric acid was predominant in the esterified bond with lignin in wheat straw.

The Formation and Photodissociation of Copper-Sulfur Cluster Ions

Copper suffer cluster ions were produced by laser ablation on solid samples: (1) a mixture of copper and sulfur powder, (2) cuprous sulfide compound, (3) cupric sulfide compound, respectively. Two main series of cluster ions were found: (a) [Cu(Cu2S)(n)](+) (n = 0 - 22), (b) [(Cu2S)(n)](+) (n = 1 - 18). The main photodissociation channels of the cluster ions were neutral losses of Cu2S, Cu or CuS. It is obvious that the Cu2S unit plays an important role in the formation and structure of the Cu/S cluster ions, and furthermore, the filled d(10) shell eletronic configuration of copper element might be critical to the characteristic of the cluster ions.

Method of treating the surface of polymers with a cuprous compound to form a copper sulphide composite structure : Lehr, M.H. (B.F. Goodrich Co., Akron, OH, USA) US Pat 4 863 635 (5 September 1989)

Method of treating the surface of polymers with a cuprous compound to form a copper sulphide composite structure : Lehr, M.H. (B.F. Goodrich Co., Akron, OH, USA) US Pat 4 863 635 (5 September 1989)

銅(I)触媒を用いたアルコールと一酸化炭素によるカルボン酸合成

銅(I)触媒を用いたアルコールと一酸化炭素によるカルボン酸合成

Cupric Oxide-Molybdenum Oxide Phase Diagram in Air and in Oxygen

Phase diagrams of the CuO-MoO3 system were determined in oxygen, in air, and under oxygen pressure. The first two diagrams are quite similar, with temperatures up to 40° higher occurring in oxygen than in air. Stable compounds obtained by low-temperature sintering were CuMoO4 and CUZMoO5, which melted incongruently at 835° and 880° in oxygen and at 812° and 840°C in air, respectively. The MoO3-CuMoO4 eutectic occurs near 30 molyo CuO at 705° in oxygen and at 700° C in air. Above temperatures as low as 865° in oxygen and 840° C in air, oxygen is lost with the production of cuprous compounds. This phenomenon probably accounts for all of the inconsistencies in previous phase diagrams. The dominant cuprous compound in the central region at high temperatures is Cu6Mo4O15, melting congruently at 880° and 895°C in air and oxygen, respectively. On cooling in oxygen-containing atmospheres, this compound changes to cupric Cu3Mo2O9. Unit cell dimensions and an indexed powder pattern are presented for this compound. Experiments under an oxygen pressure of 2 to 3 atm indicate that the cupric compounds in the simple CuO-MoO4, system without reduction are CuMoO4, Cu3Mo2O9, and Cu2MoO5, melting incongruently at 850°, 910°, and 940°C, respectively. In all atmospheres Cu3Mo2O9 is metastable with respect to CuMoO4 and Cu2MoO5 below the incongruent melting point of CuMoO4.

Sur le Comportement Anodique du Cuivre III. Etude de la Passivation

AbstractIt has been shown that anodic oxidation of copper in alkaline solutions leads to a true passivation due to the formation of a protective layer. The properties of this layer depend on various factors such as current density, structure of the metal, electrolyte concentration and temperature.In all cases investigated in this paper, the primary product of anodic oxidation was cuprous oxide. But this cuprous compound is rapidly oxidised to cupric oxide or hydroxide which are the main constituents of the final film. The formation of cupric oxide is favored by decreasing the current density and raising the temperature.

The natural activators of papain

The presence of glutathione in the latex ofCarica papaya and the press juices of pine apple, cucumber, andFicus bengalensis, has been established. The tripeptide has been isolated from the latex ofCarica papaya in the form of its cuprous compound. A quantitative estimation of glutathione has been made, employing the specific glyoxalase reaction. Glutathione is shown to be the natural activator of plant proteinases which in this respect also, are analogous to liver cathepsin and yeast proteinase.