Copper Cations Research Articles

Flame spray pyrolysis synthesized CuO-TiO2 nanoparticles for catalytic combustion of lean CO

In this work, CuO-TiO2 nanoparticles with different CuO mass contents of 2%, 8%, 12%, and 20% are synthesized by flame spray pyrolysis (FSP) method and applied to catalytic combustion of lean CO. The nano-catalyst is characterized by N2-physisorption isotherms, X-ray diffraction (XRD), transmission electron microscopy (TEM), H2-TPR (temperature-programmed reduction) and X-ray photoelectron spectroscopy (XPS). All the catalysts possess a high specific surface area, of which the CuO-TiO2 nanoparticles with 2 wt.% Cu (2CT) is as high as 98 m2/g, and exhibits a spherical structure with a diameter of 15–20 nm. Compared with other methods, the FSP method can significantly improve the loading of CuO without producing large crystalline CuO particles on the catalyst surface. Interestingly, the addition of CuO will essentially change the lattice structure of TiO2 for all catalysts, including its crystal spacing and XRD diffraction angle. Copper cations are embedded in TiO2 lattice to promote the transformation from anatase to rutile by producing oxygen defect at high flame temperature. The interaction between CuO and TiO2 has significant influence on its physicochemical properties. A lower onset reduction temperature on the sample with higher CuO loading is obtained due to the hydrogen spillover effect in H2-TPR test. Moreover, the loaded CuO increases the content of more stable rutile phase in the materials, so that it reduces the strong metal-support interaction (SMSI) effect of CuO and anatase phase to improve the properties of CO catalytic combustion. The synthesized CuO-TiO2 nanoparticles can achieve complete combustion conversion of lean CO at lower temperature of 120°C.

New complexes of Ni(II) and Cu(II) with tridentate ONO Schiff base ligand: synthesis, crystal structures, electrochemical and theoretical investigation

In this research, we prepared a new series of the Cu(II) (1) and Ni(II) (2) metal complexes of a tridentate Schiff base ligand, (E)-2-(5-bromo-2-hydroxybenzylideneamino) phenol (H2L). These complexes were characterized by elemental analysis, FT-IR, UV–Vis, and 1H-NMR spectroscopy. The crystal structures of (1) and (2) were determined by X-ray diffraction studies. The single crystal X-ray diffraction analyses revealed that copper(II) cation is five-coordinated and the coordination polyhedron is a slightly distorted square pyramid. Nickel(II), on the other hand, is four-coordinated, and has a regular, square planar geometry. Further discussed were the electrochemical reduction of these complexes. We also analyzed the nature of the metal–ligand bond in the complexes through NBO and EDA analysis. Besides, vibrational sample magnetometer (VSM) revealed complex (1) was ferromagnetic.

СОРБЦИОННОЕ ИЗВЛЕЧЕНИЕ МЕДИ НА ИОНИТЕ LEWATIT MONOPLUS TP-220 ИЗ РАСТВОРОВ АЗОТНОКИСЛОГО ВЫЩЕЛАЧИВАНИЯ МЕДНОГО КОНЦЕНТРАТА

The PURPOSE of the paper is to study the equilibrium in the system ion-exchanger TP-220 - copper-containing solution and kinetic characteristics of Lewatit TP-220 ion-exchanger as applied to the solution after the nitric acid leaching of the copper concentrate of the unpayable ore of the Zhezkazgan deposit. METHODS. Static experiments were carried out to determine sorption equilibrium. Static sorption was conducted in glass jars where the phases were mixed by mechanical agitators. The sample of the sorbent was treated for a certain time by the initial solution at the temperature of 75°C. At the end of the process the phases were separated. The solutions were sampled to analyze the content of copper and other cations. The saturated sorbent was washed with water and analyzed for the content of main components. RESULTS AND THEIR DISCUSSION. It has been determined that the isotherm of copper sorption by ion-exchanger TP-220 confirms high sorption capacity even at extremely low concentrations of copper in the initial solution. The temperature factor in the range from 20 to 50 0 С at a contact time of phases more than 60 minutes does not have any noticeable effect on the ion exchange parameters of the sorbent. CONCLUSIONS. The sorption of copper on the sorbent under investigation features high rate that ensures its maximum capacity even after 60 minute contact at room temperature, i.е. sorbent has good kinetic properties of copper sorption.

Determination of Sorption Properties of Heavy Metals in Various Biosorbents

Abstract Various techniques of determination of properties of physicochemical processes of heavy metal sorption in biosorbents were analysed. The methods of preparing and storing samples, conditions of experiment performance, as well as the methods of data interpretation were discussed. Two procedures of study were analysed: (1) in the static system of biosorbent-solution contact and (2) in the system of dynamic flow of solution. Copper cation sorption was studied. The effect of consecutive stages of the study on the quality of final results was shown. A high degree of uncertainty of the sorption capacity assessment was reported, which was dependent on the manner of conducting the study. The application of the pseudo-second order reaction model was substantiated to describe kinetics of cation-exchange sorption and the model of Langmuir isotherm to describe equilibria. The study conducted reveals that in order to perform comparative analyses, it is necessary to establish a joint concept of conducting studies and the interpretation of results.

Redox-dependent control of i-Motif DNA structure using copper cations.

Previous computational studies have shown that Cu+ can act as a substitute for H+ to support formation of cytosine (C) dimers with similar conformation to the hemi-protonated base pair found in i-motif DNA. Through a range of biophysical methods, we provide experimental evidence to support the hypothesis that Cu+ can mediate C–C base pairing in i-motif DNA and preserve i-motif structure. These effects can be reversed using a metal chelator, or exposure to ambient oxygen in the air that drives oxidation of Cu+ to Cu2+, a comparatively weak ligand. Herein, we present a dynamic and redox-sensitive system for conformational control of an i-motif forming DNA sequence in response to copper cations.

Conductivity Enhancement of Nickel Oxide by Copper Cation Codoping for Hybrid Organic-Inorganic Light-Emitting Diodes

We demonstrate a Cu(I) and Cu(II) codoped nickel(II) oxide (NiOx) hole injection layer (HIL) for solution-processed hybrid organic-inorganic light-emitting diodes (HyLEDs). Codoped NiOx films show no degradation on optical properties in the visible range (400–700 nm) but have enhanced electrical properties compared to those of conventional Cu(II)-only doped NiOx film. Codoped NiOx film shows an over four times increased vertical current in comparison with that of NiOx in conductive atomic force microscopy (c-AFM) configuration. Moreover, the hole injection ability of codoped NiOx is also improved, which has ionization energy of 5.45 eV, 0.14 eV higher than the value of NiOx film. These improvements are a consequence of surface chemical composition change in NiOx due to Cu cation codoping. More off-stoichiometric NiOx formed by codoping includes a large amount of Ni vacancies, which lead to better electrical properties. Density functional theory calculations also show that Cu doped NiO model structure with...

Chemically Tunable Formation of Different Discrete, Oligomeric, and Polymeric Self-Assembled Structures from Digold Metallotweezers.

Digold metallotweezers whose complex supramolecular landscape is controlled by adding a series of metal cations are described. The metallotweezers have a strong tendency to form interesting supramolecular structures on addition of Tl+ , Ag+ , and Cu+ . The choice of the cation can be used to direct the formation of a designated molecular architecture. The addition of thallium facilitates the formation of a self-aggregated duplex structure in which the cation occupies the cavity of the dimer. The same type of structure is formed when Cu+ is added, and the resulting duplex inclusion complex shows interesting vapochromic properties. This copper-encapsulating system evolves in solution to a 1D helical supramolecular polymer showing multiple aurophilic and Au⋅⋅⋅Cu interactions, in which the copper cation is bound to several alkynyl ligands of the tweezer. The addition of a small amount of silver cations to the digold tweezer yields a similar type of inclusion dimer complex, but adding an excess of the cation produces new discrete molecules presumably exhibiting multiple Au⋅⋅⋅Au, Au⋅⋅⋅Ag, and Ag⋅⋅⋅Ag metallophilic interactions. The differences in the supramolecular structures formed are ascribed to the different tendencies of the metal cations to exhibit interactions with the gold atoms and to coordinate to the alkynyl ligands of the tweezer.

A new Cu(II) coordination polymer constructed from two kinds of ligands and rare [Ta2OF10]2− anion: synthesis, crystal structure and fluorescent properties

A new zigzag chain coordination polymer {[Cu2(opdc)2(phen)2][Ta2OF10]}n [(opdc): 2-oxidopyridinium-3-carboxylate, phen: 1, 10-phenanthroline] has been synthesized by a two-step hydrothermal method and characterized by elemental analysis, energy-dispersive X-ray spectroscopy (EDS), infrared (IR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and X-ray single-crystal diffraction studies. In its structure, each Cu(II) cation is coordinated by two N atoms from one phen ligand and three O atoms from two different opdc− anions to furnish a distorted square pyramidal configuration. Neighboring two copper cations are bridged by one carboxylate group from opdc ligand in an anti-anti bridging mode, leading to a 1-D infinite zigzag chain. The linear dinuclear [Ta2OF10]2− anions are further linked to the zigzag chain through intermolecular NH⋯F and CH⋯F hydrogen bonds. Moreover, the fluorescence emission, quantum yield and decay lifetime of the compound were also investigated.

Simultaneous determination of copper(II) and zinc(II) via simple acid-base titrimetry using glass pH electrode

The combination of potentiometric methods with multivariate calibration techniques allows complex mixtures to be analyzed. In this study, a new method was developed and reported for simultaneous determination of copper(II) and zinc(II) cations in a mixture by titrimetric methods. The developed method permits simultaneous cation analysis with low detection limits, just by using a pH electrode. This work has achieved the challenging goal of developing a cost-effective and applicable method that can be applied in most laboratories due to independence of any chemical instruments. Partial least squares 1, one of the multivariate calibration techniques, was used in the analysis of titrimetric data. Copper(II) and zinc(II) were simultaneously determined with approximately 5 ppm detection limits and the developed method was validated by performing the titration with known sample mixtures and a certificated alloy sample.

Separation of cations of heavy metalsfrom concentrated galvanic drains

When applying galvanic coatings, soluble salts of heavy metals such as iron, copper, nickel, zinc, cadmium, chromium and other metals are used, toxic cations enter the water, with subsequent migration to the biosphere. To date, many methods have been developed for cleaning galvanic sewage, which cannot be considered sufficiently effective. The joint sorption of divalent cations of copper, nickel and cadmium from concentrated aqueous solutions was investigated. Calculation and experimental methods were used to determine the separation conditions of the bivalent ion systems that differed and close in sorption properties on the aminophosphonic polyampholyte Purolite S950 in a natrium form. It is shown that the cadmium (II) cations can be isolated from solutions containing copper (II) or nickel (II) cations even at the height of the sorption layer of 0.13 m due to the difference in the defining characteristics of the cations. This layer height can be used not only in a chromatographic column, but also in a concentrating cartridge. Separation of the copper (II) and nickel (II) close to the sorption properties requires an absorbing layer of 0.76 m, which can only be used in a chromatographic column, but not for a concentrating cartridge. In this paper, the degrees of ion separation in various sorption conditions are calculated. The applicability of the conductometric method for controlling the ion exchange process is shown not only when the free cations are isolated from aqueous solutions but also bound to complexes.

The compounds of leucine with copper (II) cations in aqueous solutions

The structure of alpha-amino acids offers the possibility of the formation of a large number of forms coordination compounds with cations of metals All forms of amino acids can participate in complexation reactions with metal cations: protonated form with metal ions adducts by coordinating with unshared electron pairs of oxygen atoms of carboxyl groups, the stability constants of such complexes are small and they usually like solvate complexes; bipolar and deprotonated forms not only adducts, but also chelation. The study of equilibrium in the system of amino acid - metal cation are most often carried out potentiometric and spectrophotometric methods, allowing fast, with good reproducibility to determine the equilibrium concentration and composition of the solution without displacement of the chemical equilibrium. In the literature, a chelate compound of leucine with copper (II) cations, formed in an alkaline medium with stability constants of 7.89 and 6.45, has been studied in sufficient detail. This paper presents a study of the conditions of complex formation in neutral aqueous solutions in the system containing aliphatic amino acid L, D-leucine and copper cations (II). The difference in the wavelengths corresponding to the maximum optical density indicates a change in the composition of the aqueous solution and the presence of copper leucinate compounds. The existence of a complex compound between bipolar leucine ions and copper (II) cations in neutral aqueous solutions of the composition (СuLеu4)2+ was proved by the spectrophotometric method of isomolar series. For the determination of stability constants using the method of J. Bjerrum with the following assumptions: an amino acid was regarded as monobasic weak acid, the stability constant of complex compounds was calculated as the average of all functional groups of leucine. Defined in the work a measure of stability constants protonated compounds composition (СuLеu4)2+ is equal to 4.27.

Modulating metallopolymer mechanical properties by controlling metal ligand crosslinking

Adjustable materials based on controlling the metal ligand interactions in metal containing polymers are prepared and characterized. Copper(II) carboxylate is used to crosslink a stretchable acrylic polymer, resulting in increased stiffness and strength. Moreover, modulation of the material properties is accomplished by attaching different ligands to the copper cations.

Rationalizing Fabrication and Design Toward Highly Efficient and Stable Blue Light‐Emitting Electrochemical Cells Based on NHC Copper(I) Complexes

AbstractRecently, the use of a new family of electroluminescent copper(I) complexes—i.e., the archetypal [Cu(IPr)(3‐Medpa)][PF6] complex; IPr: 1,3‐bis‐(2,6‐di‐iso‐propylphenyl)imidazole‐2‐ylidene; 3‐Medpa: 2,2′‐bis‐(3‐methylpyridyl)amine—has led to blue light‐emitting electrochemical cells (LECs) featuring luminances of 20 cd m−2, stabilities of 4 mJ, and efficiencies of 0.17 cd A−1. Herein, this study rationalizes how to enhance these figures‐of‐merit optimizing both device fabrication and design. On one hand, a comprehensive spectroscopic and electrochemical study reveals the degradation of this novel emitter in common solvents used for LEC fabrication, as well as the impact on the photoluminescence features of thin‐films. On the other hand, spectro‐electrochemical and electrochemical impedance spectroscopy assays suggest that the device performance is strongly limited by the irreversible formation of oxidized species that mainly act as carrier trappers and luminance quenchers. Based on all of the aforementioned, device optimization was realized using ionic additives and a hole transporter either as a host–guest or as a multilayered architecture approach to decouple hole/electron injection. The latter significantly enhances the LEC performance, reaching luminances of 160 cd m−2, stabilities of 32.7 mJ, and efficiencies of 1.2 cd A−1. Overall, this work highlights the need of optimizing both device fabrication and design toward highly efficient and stable LECs based on cationic copper(I) complexes.

Copper-loaded nanocellulose sponge as a sustainable catalyst for regioselective hydroboration of alkynes

It is desirable for catalyst supports to be biodegradable, easily-modifiable, and possessing high surface area. In this work, thiolated nanocellulose sponge was prepared from hydrolytic silane condensation of cellulose nanofibrils (CNF) and used as a green support to immobilize copper cations via in situ CuII to CuI reduction and complexation. The sponge featured high porosity (90.5%) and low density (29.4 mg/cm3) with regular morphology. The sponge easily recovered 94% of its original shape in water after experiencing 80% deformation under stress of 95 kPa. When used in catalyzing hydroboration of alkynes, excellent conversion and up to 99% regioselectivity were achieved with the copper-loaded sponge. The sponge-supported catalysts worked well in the absence of additional ligands, had a broad substrate scope, and retained 93% of their activity after six catalytic cycles. This simple and scalable strategy offers an efficient route for immobilizing metal catalysts on porous supports.

Novel Mixed Complexes of Copper(II) and Ethylenediamine: Synthesis, Crystal Structure, and Catalytic Activity in the Cross-Coupling Reaction of 1-Phenyl-5H-tetrazole-5-thiol and Iodobenzene

Two earlier unknown complexes, [Cu(en)2(Hptt)]Br (Hptt = 1-phenyl-1H-terazole-5-thiol, en = ethylenediamine) and trans-[Cu(en)2(H2O)Br]Br, have been synthesized and characterized using X-ray diffraction analysis. In [Cu(en)2(Hptt)]Br complex, the copper cation is bonded with the N4 atom of tetrazole ring. Catalytic activity of the obtained complexes in cross-coupling reaction of 1-phenyl-5H-tetrazole-5-thiol with iodobenzene is comparable to that of CuBr2 in the presence of 2 eq. of ethylenediamine.

Structure and Electrocatalytic Properties of Copper-Containing Aniline–Melamine–Formaldehyde Polymer Composites

Mixed aniline–melamine–formaldehyde polymer was synthesized by parallel polycondensation of the monomers with formaldehyde. Copper(II) chloride and copper oxides (CuO, Cu2O) were introduced in situ the process. X-ray diffraction analysis revealed the presence of crystalline CuO phases at introducing CuCl2 into the polymer and the appearance of copper particles in all the synthesized composites after using them as catalysts in electrohydrogenation of o-nitroaniline, which is caused by electrochemical reduction of copper cations from copper oxides. The use of the synthesized composites for the cathode activation in electrohydrogenation of o-nitroaniline increases the process rate by a factor of 1.5–2.5 compared to electrochemical reduction, and with 100% conversion to o-phenylenediamine.

(Metformin-κ2N,N′)(salicylato-κ2O,O′)copper(II) trihydrate

The hydrous title complex [systematic name: (1,1-dimethylbiguanide-κ2N2,N4)(2-oxidobenzoato-κ2O,O′)copper(II) trihydrate], [Cu(C7H4O3)(C4H11N5)]·3H2O, was synthesized electrolytically from an ethanolic solution of metformin hydrochloride, acetylsalicylic acid, Pepto-Bismol and a copper sacrificial anode. Diffraction data were collected at 0.56 Å resolution, allowing the accurate determination of H-atom positions in the neutral metformin ligand. Both imine groups in metformin have very similar N=C bond lengths, 1.2978 (17) and 1.3033 (17) Å, and the salicylate dianion behaves as a chelating ligand. The coordination sphere of the copper(II) cation deviates marginally from a square-planar arrangement. In the crystal, short Cu...Cu separations of 3.5476 (3) Å are observed, along with classical hydrogen-bonding interactions.

Selective formation of lanthanum phosphate from lanthanum–copper solutions

Neodymium–iron and samarium–cobalt–iron–copper alloys are typically used to produce magnets. As neodymium and samarium are rare earth elements, they are precious and expensive; consequently, they are often recovered by recycling processes to reduce costs. Recently, a novel technique to recover neodymium and samarium has been reported that avoids the reported difficulties of previous methods. Because rare earth phosphates are the main components of rare earth ores, a novel phosphate process was suggested. However, the presence of copper cations complicated recovery from samarium–cobalt–iron–copper solutions. Therefore, in this work, to clarify the behavior of copper, we investigated the preparation of lanthanum phosphate from lanthanum–copper solutions. A lanthanum–copper solution was mixed with a phosphoric acid solution and then the pH was adjusted using sodium hydroxide solution. The precipitates formed at various pH values were filtered and dried. The ratio of lanthanum and copper in the precipitates was estimated by inductively coupled plasma optical emission spectrometry. As the ideal, the lanthanum phosphate was filtered out, so the filtrate contained the copper ions. Furthermore, the phosphoric acid concentration was varied to study precipitation in the absence of copper compounds. Lanthanum phosphate containing a small amount of copper was obtained using the developed process. This phosphate process was found to be useful for recovering rare earth elements, and it may be applicable to the recycling and recovery of other rare earth elements of interest.

Theoretical study of nitrogen dioxide and nitric oxide co-adsorption and DeNOx reaction on Cu-SAPO−34 and Cu-SSZ−13 in presence of Brønsted acid sites

The decоmposition of co-adsorbed nitric oxide (NO) and nitrogen dioxide (NO2) on copper-exchanged SAPO−34 and SSZ−13 proceeds with lower activation barriers in all intermediate steps, as compared to the DeNOx reaction of dinitrosyls. Upon co-adsorption on copper cations, NO and NO2 form an η1O adsorption complex with NN bond and in the presence of Brønsted acid sites, oxygen atoms from the adsorption complex bind to the framework via hydrogen bonds. Direct protonation of the adsorption complex may occur at either the NO2 end (ONNO2H), or at the NO-end, (HONNO2). Upon ONNO2H formation, the NN bond is weakened, while NO protonation (HONNO2) strengthens the NN bond and a nearly cyclic structure with the transition metal cation is formed. Two of the reaction steps have high energy barriers: the release of N2O on SSZ−13 after protonation transfer to ONNO2, and the decomposition of N2O on a ZeolCuO site. The first reaction step is the release of N2O and protonation of the adsorption complex plays a detrimental role. The activation barrier obtained by intrinsic reaction coordinate calculations is higher for SSZ−13 (116 kJ mol−1), but much smaller for SAPO−34 (65 kJ mol−1). After desorption of molecular oxygen, the N2O molecule is re-adsorbed and its dissociation with release of molecular nitrogen is assisted by hydrogen bond formation, which stabilizes the transition states and lowers the energy barriers. After the release of molecular nitrogen, surface copper oxide, ZeolCuO site is left and it is more reactive than copper hydroxyl, ZeolCu(OH)+.

Crystal Structure and Characterization of Two Layered Copper(II) Coordination Polymers with Anions of 3‐Phosphonopropionic Acid and (RS)‐2‐Phosphonobutyric Acid

Blue single crystals of Cu[μ3‐O3P(CH2)2COOH]·2H2O (1) and Cu[(RS)‐μ3‐O3PCH(C2H5)COOH]·3H2O (2) were prepared in aqueous solutions (pH = 2.5–3.5). 1 crystallizes in space group Pbca (no. 61) with a = 812.5(2), b = 919.00(9), and c = 2102.3(2) pm. Cu2+ is fivefold coordinated by three oxygen atoms stemming from [O3P(CH2)2COOH]2– anions and two water molecules. The Cu–O bond lengths range from 194.0(3) to 231.8(4) pm. The connection between the [O3P(CH2)2COOH]2– anions and the Cu2+ cations yields a polymeric structure with layers parallel to (001). The layers are linked by hydrogen bonds. 2 crystallizes in space group Pbca (no. 61) with a = 1007.17(14), b = 961.2(3), c = 2180.9(4) pm. The copper cations are surrounded by five oxygen atoms in a square pyramidal fashion with Cu–O bonds between 193.6(4) and 236.9(4) pm. The coordination between [O3PCH(C2H5)COOH]2– and Cu2+ results in infinite puckered layers parallel to (001). The layers are not connected by any hydrogen bonds. Each layer contains both R and S isomers of the [O3PCH(C2H5)COOH]2– dianion. Water molecules not bound to Cu2+ are intercalated between the layers. UV/Vis spectra suggest three d–d transition bands at 743, 892, 1016 nm for 1 and four bands at 741, 838, 957, and 1151 nm for 2, respectively. Magnetic measurements suggest a weak antiferromagnetic coupling between Cu2+ due to a super‐superexchange interaction. Thermoanalytical investigations in air show that the compounds are stable up to 95 °C (1) and 65 °C (2), respectively.