Neutral Copper Research Articles

Analysis of an Iron-Copper Alloy by Calibration-Free Laser-Induced Breakdown Spectroscopy (CF-LIBS) and Inductively Coupled Plasma – Mass Spectrometry (ICP-MS)

The purpose of the present work was to monitor the reliability of the calibration-free laser-induced breakdown spectroscopy (CF-LIBS) by comparing the results with inductively coupled plasma - mass spectrometry (ICP-MS). For the laser ablation studies, the plasma was generated by a Q-switched Nd: YAG laser, and the emission spectra of the alloy sample were recorded using a set of Avantes spectrometers covering the wavelength region from 250 to 870 nm. Optical emission spectra confirmed that copper and iron are the major constituents while traces of sodium and magnesium were also observed. The Boltzmann plot method was employed to calculate the plasma temperature to be (8400 to 8700) ± 1000 K using the neutral lines of iron and copper. The electron number density was calculated using the Stark broadened line profiles of the neutral copper lines to be (2.2 ± 0.2) × 1016 cm−3. The relative compositions of iron and copper were determined to be 23.85 ± 5% and 76 ± 5% using CF-LIBS. To validate the method, the composition of the alloy was also determined using inductively coupled plasma – mass spectrometry (ICP-MS) and the results were excellent agreement with those by CF-LIBS. This study demonstrated that CF-LIBS is a powerful and reliable tool for quality control of alloys.

Syntheses, Characterization, and X-Ray Crystal Structure of a Co-Crystal Containing One Neutral Mononuclear Copper (II) Unit and One Cationic Dinuclear Copper (II) Unit Assembled with Schiff Base and Perchlorate Copper(II) Salt

The use of 2-{[2-(2-hydroxybenzylideneamino)phenylimino]methyl}phenol (H2L) in metal transition chemistry has yielded a co-crystal which is composed by one neutral mononuclear, one cationic dinuclear and one perchlorate anion. During the formation of the complex, one of the salicylaldimine groups of one of the molecules of the H2L ligand hydrolyzed to form an asymmetrical ligand with an amino group leading to the molecule (2-((2-aminophenylimino)methyl)phenol (HL'). The complex was formulated as {[Cu(L)].[Cu2(L)(L')]}.(ClO4). The structure of the complex was solved by single crystal X-ray crystallography. In the mononuclear unit, the Cu2+ atom is coordinated by one dideprotonated molecule of the ligand acting in tetradentate fashion. In the dinuclear unit, one the Cu2+ atom is coordinated by one dideprotonated molecule of the ligand acting in tetradentate fashion and the other Cu2+ is coordinated by the monodeprotonated (2-((2-aminophenylimino)methyl)phenol (HL') acting in tridentate fashion. The two Cu2+ are bridged by the two phenoxo oxygen atoms of the dideprotonated molecule of the ligand. The complex crystallizes in the triclinic space group Pī with the following parameters: a = 13.8864 (3) Å, b = 14.2078 (4) Å, c = 14.5007 (4)) Å, α = 64.593 (3), β = 71.353 (2), γ = 71.707 (2)°, V = 2395.80 (13) Å3, Z = 2, R1 = 0.037, wR2 = 0.041. The supramolecular structures are consolidated by multiple hydrogen bonds.

Theoretical determination of corrosion inhibitor activities of 4-allyl-5-(pyridin-4-yl)-4H-1,2,4-triazole-3-thiol-thione tautomerism

Using the density functional method B3LYP/6-311G(d,p) calculations, the inhibitor activity of 4-allyl-5-(pyridin-4-yl)-4H-1,2,4-triazole-3-thiol tautomerism against corrosion of neutral copper surfaces has been investigated. Among the inhibitors tested, the 4-allyl-5-(pyridin-4-yl)-4H-1,2,4-triazole-3-thiol inhibitor has the inhibition performance for both forms (thiol and thione). Quantum chemical parameters that are correlated to the inhibition efficiency including highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital, (LUMO), energy bandgap (ΔE), electronegativity (χ), Hardness (ɳ), softness (σ), dipole moment (μ), the fraction of the electrons transferred (ΔE), and Total energy (TE) has been calculated. In addition, the adsorption of inhibitors on the neutral copper surface reveals that nitrogen adsorption is preferred over sulfur adsorption. The results show that the thione form has the highest inhibitor compared to the thiol form.

Effectiveness of neutral electrolyzed water and copper oxychloride on fungi spores isolated from tropical fruits

The aim of this study was to assess the antifungal effectiveness of neutral electrolyzed water (NEW) to inhibit the spore germination of post-harvest fungi common in fruits, determine the required available chlorine concentration (ACC) of NEW and to compare it with copper oxychloride (CO) and sterile distilled water (SDW) in vitro. This study evaluated the biological effectiveness of NEW to inactivate pure cultures of 11 different fungi obtained from post-harvest tropical fruits with anthracnose, rottenness or necrosis symptoms. A conidial solution of 1 × 104 spores/mL per culture was prepared and treated with a low, medium and high ACC of NEW (pH 7.0 ± 0.05, 12, 33 and 53 mg/L of ACC and ORP of 850 mV), CO at 0.3 g/L, or sterile distilled water as a control, for 3-, 5- and 10-min contact time. Spore germination of Alternaria alternata, Botrytis cinerea, Cladosporium australiense, Colletotrichum gloeosporioides and C. siamense, Fusarium solani and F. oxysporum, and Lasiodiplodia theobromae was inhibited in 100% by NEW at 12, 33 and 53 ppm ACC; 3,5 and 10 min contact time. Aspergillus niger and A. tamarii required 53 mg/L ACC to inhibit 100% of spore germination. NEW at 33 and 12 mg/L inhibited around 50% and <25% of A. niger spore germination, respectively. NEW at 53 mg/L ACC was the most efficient treatment against Rhizopus stolonifer but only inhibited spore germination in ∼25%. CO inhibited spore germination by 100% of A. alternata, B. cinerea, C. australiense, C. gloeosporioides, C. siamense and L. theobromae. However, CO inhibited <25% of spore germination of F. solani, F. oxysporum, A. niger, A. tamarii and R. stolonifer. NEW and CO had a significant effect on every fungus compared to a SDW treatment. SDW was the least effective treatment, followed by CO. NEW at 12 mg/L and 33 mg/L ACC were equally effective in eliminating the fungi, and more effective than CO. NEW at a concentration of 53 mg/L ACC was the most effective treatment. Results obtained in this study show that NEW has effectively inhibited spore germination of these species, and this treatment could be used as a substitute an ecological novel alternative to CO to avoid spore growth in the above-mentioned fruits.

An Investigation of Discoloured Oil-bound Copper Green Glazes in a Seventeenth-century Harpsichord Lid, With Reference to Reconstructions

ABSTRACT This study focuses on copper green glazes on the front and reverse schemes of a seventeenth-century harpsichord lid painting. The aim was to investigate the materials and techniques of the copper-based green paints and their brown discolouration, a phenomenon commonly encountered in glazes made with the pigment verdigris (basic and neutral copper acetate). The study summarises the historical materials and recipes for copper green glazes, and includes a review of hypotheses that have been proposed for discolouration, focusing on findings from investigations that have been conducted in laboratory environments into the chemical interactions between verdigris and linseed oil. Analyses, using optical microscopy, SEM-EDX, XRD, THM-Py-GC-MS and ATR-FTIR, were conducted on paint samples from the browned copper green glazes from the front and reverse of the painted lid. To link the laboratory studies with the information known from historical texts and technical analysis of the object, analysis was also conducted in tandem on reconstructions, comprising neutral copper acetate in linseed oil. These were made and previously studied as part of the MOLART project (1995–2000), based on historical paint recipes. The analysis of the MOLART reconstructions supports the idea of a correlation between pigment-medium interaction and oxidation. Results from analysis of the painted lid support the idea that artists used a range of copper-based pigments for green glazes besides copper acetate, and illustrate different techniques for the glazes used within the interior and exterior painted schemes.

Structure prediction of neutral physiological copper(II) compounds with l-cysteine and l-histidine

Bis(aminoacidato)copper(II) [CuII(aa)2] coordination compounds are the physiological species of copper(II) amino acid compounds in blood plasma. Since there are no experimental data in the literature about the geometries that physiological CuII(aa)2 could form with l-cysteine (Cys), that is, for bis(l-cysteinato)copper(II) [Cu(Cys)2] and the ternary (l-histidinato)(l-cysteinato)copper(II) [Cu(His)(Cys)], this paper computationally examines the possible conformations that the two compounds could form with the Cys ligand having a protonated sulfur, as in the conventional zwitterion, which was determined to be prevailing in aqueous solution. These two amino acids can bind metals in a tridentate fashion and thus form many possible coordination patterns. Density functional calculations were performed for the conformational analyses in the gas phase and in implicitly modeled aqueous solution using a polarizable continuum model. Additionally, we examine which coordination mode, with thiol or thiolate group, is more stable. The Cys coordination via the amino N and carboxylato O atoms (a glycinato mode) is obtained as the most stable one in aqueous Cu(Cys)2, and also in Cu(His)(Cys) when the His glycinato or histaminato mode combines with the intact thiol group. Whereas the conformers with N and thiol S as the copper(II) donor atoms are predicted to be the least stable, those with the Cu–N and Cu–S(thiolate) bonding (and protonated carboxylato group) are the most stable. The differences are explained by different covalent and ionic contributions of Cu–S(thiol) vs. Cu–S(thiolate). The study can contribute to the insight into formation and reactivity of the copper(II) cysteinato complexes in solution.

Synthesis and structure of a mixed ligand copper(II) compound based on a distorted {CuN2O3} square pyramid

The synthesis, spectra, thermal study and crystal structure of a mixed ligand copper(II) compound viz. [Cu(biq)(acac)(NO 3 )] 1 (biq = 2,2′-biquinoline, acac = acetylacetonate) are reported. The {CuN 2 O 3 } coordination sphere is made up of two oxygen atoms of an unique acac ligand, an oxygen of the nitrate group and one N atom of biq ligand which form the basal plane {CuNO 3 } of a square pyramid. A second nitrogen atom of the biq ligand occupies the apical position resulting in a distorted square pyramidal {CuN 2 O 3 } polyhedron. In the crystal structure, each neutral square pyramidal copper(II) species is linked with two symmetry related molecules with the aid of intermolecular C-H×××O hydrogen bonding interactions. A study of fifteen mixed ligand copper(II) acetylacetonates reveals that in this series of compounds, 1 exhibits maximum deviation of the {CuN 2 O 3 } polyhedron from square pyramidal towards trigonal bipyramidal geometry.

Controlling the plasma electron number density of copper metal using NIR picosecond laser-induced plasma spectroscopy

In this paper, we investigate a new method to control the plasma electron number density of copper metal using a near-infrared (NIR) picosecond Nd:YAG laser-induced plasma spectroscopy (LIPS) technique. The applied laser parameters are as follows; laser pulse energy and intensity varied from 29.2 to 59.4 mJ ± 3% and from 6.01×1010 to 12.35×1010 W/cm2 ± 5%, respectively, for a single pulse at 170 ps pulse duration, and beam diameter about 0.5 ± 0.1 mm. By considering the Stark broadening of a specific spectral line, electron density can be calculated using a neutral copper line at 521.8 nm, assuming the local thermodynamic equilibrium (LTE) condition. The observed electron density values were 1.09×1016, 2.24×1016, 3.60×1016, and 4.75×1016 cm–3 for the laser pulse energies 29.2, 41, 52.4, and 59.4 mJ, respectively. The plasma electron density values are increased with the increase in laser pulse energy. Such findings were interpreted due to an increase in the mass ablation rates with laser pulse energy. The obtained results explore the ability to control the plasma electron density by controlling the picosecond pulse energy. These results can contribute to the development of plasma technologies and their applications in many fields.

Dithiol-Dithione Tautomerism of 2,3-Pyrazinedithiol in the Synthesis of Copper and Silver Coordination Compounds.

A promising strategy for new electrically conductive coordination polymers is the combination of d10 metal ions, which tolerate short metal···metal distances, with dithiolene linkers, known for their "non-innocent" redox behavior. This study explores the coordination chemistry of 2,3-pyrazinedithiol (H2pdt) toward Cu+ and Ag+ ions, highlighting similarities and differences. The synthetic approach, starting with the fully protonated ligand, allowed the isolation of a homoleptic bis(dithiolene) complex with formal CuI atoms, [Cu(H2pdt)2]Cl (1). This complex was further transformed to a 1D coordination polymer with short metal···metal distances, 1D[Cu(Hpdt)] (2Cu). The larger Ag+ ion directly built up a very similar coordination polymer, 1D[Ag(Hpdt)] (2Ag), without any appearance of an intermediate metal complex. The coordination polymer 1D[Cu(H2pdt)I] (4), like complex 1, bears fully protonated H2pdt ligands in their dithione form. Upon heating, both compounds underwent auto-oxidation coupled with a dehydrogenation of the ligand to form the open-shell neutral copper(II) complex [Cu(Hpdt)2] (3) and the coordination polymer 1D[Cu2I2(H2pdt)(Hpdt)] (5), respectively. For all presented compounds, crystal structures are discussed in-depth. Furthermore, properties of 1, 3, and those of the three 1D coordination polymers, 2Ag, 2Cu, and 4, were investigated by UV-vis-NIR spectroscopy, cyclic voltammetry, and variable-temperature magnetic susceptibility, and direct current (dc)-conductivity measurements. The experimental results are compared and discussed with the aid of DFT simulations.

Measurement of the Electron Temperature in a Metallic Copper Using Ultrafast Laser-Induced Breakdown Spectroscopy

In this paper, we provide the laser-induced breakdown spectroscopic (LIBS) analysis of copper under the action of the ultrafast picosecond Nd:YAG laser and the specifications calculated from the electron temperature of plasma generated by the fundamental (1064 nm), second (532 nm), third (355 nm), and fourth (266 nm) laser harmonics. In this work, a laser pulse energy of 60 mJ±5% with a duration of 170 ps, a beam diameter of ∼0.5±0.1 mm, and a laser intensity 1.79∙1011 W/cm2 ±8% for a single shot was applied. The electron temperature is measured using three spectral lines of neutral copper (Cu I) at 515.3, 521.8, and 522.0 nm, according to the Boltzmann plot model where the local thermodynamic equilibrium (LTE) conditions were assumed. The electron temperature values observed are 13422, 15152, 16605, and 17783K for laser wavelengths of 266, 355, 532, and 1064 nm, respectively. The experimental analysis reveals that the plasma electron temperature rises with the laser wavelength. Variations in the mass ablation rate, inverse Bremsstrahlung absorption, and photoionization with the laser wavelength variation allow us to explore the interaction dynamics. The results obtained allow for variation of the generated plasma electron temperature by guiding the picosecond pulse wavelengths; the later may allow for controlling plasma interactions, which can be applied in plasma spectroscopy of material science.

Effect of arbuscular mycorrhizal inoculation on the quality and in vitro gas production of einkorn wheat straw

The purpose of this study was to determine the effects of arbuscular mycorrhizal (AM) inoculation on the quality of einkorn wheat straw (EWS) and in vitro gas production (GP). It was found that AM inoculation of EW seed before sowing caused significant increases in crude protein (CP), ether extract (EE), neutral detergent fibre (NDF), zinc (Zn), copper (Cu), and iron (Fe) levels of straw, and a (P &lt;0.05) decrease in crude ash (CA), metabolizable energy (ME), and organic matter digestibility (OMD) compared with the straw of non-inoculated EW. The observed difference in the average GP among the between EWS from plants grown from inoculated seed and those from the untreated control was significant at all times between the third and 96th hour. However, when the GP kinetics of the groups was examined after 96 hours’ incubation, only the difference in the gas amount of the easily soluble fractions of feeds was significant. The GP from the slowly fermented part, the GP rate constant and the potential GP of the straws were not affected by the AM inoculation (P &gt;0.05). Thus, inoculation of einkorn wheat with AM altered the nutritional value of the straw produced creating a roughage with decreased value for feeding ruminant livestock.&#x0D; Keywords: artificial rumen, fermentation kinetics, nutrient digestibility

NLTE analysis of high-resolution H-band spectra IV: neutral copper

To obtain reliable Cu abundances with the APOGEE H-band spectra, it is important to investigate the non-local thermodynamic equilibrium (NLTE) effects on the formation of the H-band Cu I lines. In addition, the Cu atomic model needs to be tested. Based on both the high-resolution and high signal-to-noise ratio H-band spectra from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) and optical data, we derived the LTE and NLTE copper abundances of 13 FGK sample stars with the spectral synthesis method. We find that the NLTE effects are negligible for the Cu I 16005.7Å line in the IR H-band. Consistent copper abundances within the uncertainties from these two sets of lines have been obtained, which indicates the reliability of our NLTE copper atomic model. We note that the [Cu/Fe] ratios increase with increasing metallicity when ∼ – 1.4 dex < [Fe/H] < ∼ – 0.5 dex, favoring a secondary (metallicity-dependent) copper production.

Syntheses, structures and magnetic behaviors of 1D and 3D µ1,5-dicyanamide bridged copper(II) coordination polymers containing a symmetrical 1,2-diamine as a chelator

Two neutral copper(II) coordination polymers, [Cu(en)(µ1,5-dca)(dca)]n (1) and [Cu3(en)2(µ1,5-dca)6]n (2) [en = 1,2-ethanediamine, dca = dicyanamide], with µ1,5-dicyanamide bridges have been isolated. X-ray structural analysis reveals that each Cu(II) center in the asymmetric unit of 1 adopts a distorted square pyramidal geometry with a CuN5 chromophore ligated through two N atoms of the symmetrical 1,2-ethanediamine (en) ligand, one nitrile N atom of a terminal dca ligand and two nitrile N atoms of the μ1,5 bridging dca ligand. 1 is an example of coordination polymer containing both μ1,5-dca and terminal dca. Adjacent copper atoms are connected by dca ligands in the μ1,5-bridging mode affording a 1D chain structure. In the crystalline state, these 1D chains are further associated through weak intermolecular NH⋯N hydrogen bonds to form a 2D sheet structure, viewed along the crystallographic b axis. The asymmetric unit of 2 contains two types of copper(II) centers (Cu1 and Cu2). Cu1 adopts a distorted square pyramidal geometry with a CuN5 chromophore coordinated through two N atoms of the bidentate ligand (en) and three nitrile N atoms of three different μ1,5 bridged dca ligands, whereas Cu2 is connected to six nitrile atoms of six different μ1,5 bridged dca ligands, resulting in a distorted octahedral geometry with a CuN6 chromophore. Adjacent copper atoms are connected by μ1,5-bridging dca ligands to form a 3D network coordination polymer structure, which contains multiple NH∙∙∙N hydrogen bonds in the crystalline state. A variable-temperature magnetic susceptibility study shows very weak antiferromagnetic interactions among the neighboring metal centers through the μ1,5-dca bridges with J = −0.12 cm−1 for complex 1 and J = −0.19 cm−1 for complex 2.

UV/Vis Spectroscopy of Copper Formate Clusters: Insight into Metal-Ligand Photochemistry.

The electronic structure and photochemistry of copper formate clusters, CuI 2(HCO2)3 − and CuII n(HCO2)2n+1 −, n≤8, are investigated in the gas phase by using UV/Vis spectroscopy in combination with quantum chemical calculations. A clear difference in the spectra of clusters with CuI and CuII copper ions is observed. For the CuI species, transitions between copper d and s/p orbitals are recorded. For stoichiometric CuII formate clusters, the spectra are dominated by copper d–d transitions and charge‐transfer excitations from formate to the vacant copper d orbital. Calculations reveal the existence of several energetically low‐lying isomers, and the energetic position of the electronic transitions depends strongly on the specific isomer. The oxidation state of the copper centers governs the photochemistry. In CuII(HCO2)3 −, fast internal conversion into the electronic ground state is observed, leading to statistical dissociation; for charge‐transfer excitations, specific excited‐state reaction channels are observed in addition, such as formyloxyl radical loss. In CuI 2(HCO2)3 −, the system relaxes to a local minimum on an excited‐state potential‐energy surface and might undergo fluorescence or reach a conical intersection to the ground state; in both cases, this provides substantial energy for statistical decomposition. Alternatively, a CuII(HCO2)3Cu0− biradical structure is formed in the excited state, which gives rise to the photochemical loss of a neutral copper atom.

C(sp3)-CF3 Reductive Elimination from a Five-Coordinate Neutral Copper(III) Complex.

The reductive elimination from a high-valent late-transition-metal complex for the formation of a carbon-carbon or carbon-heteroatom bond represents a fundamental product-forming step in a number of catalytic processes. While reductive eliminations from well-defined Pt(IV), Pd(IV), Ni(III)/Ni(IV), and Au(III) complexes have been studied, the analogous reactions from neutral Cu(III) complexes remain largely unexplored. Herein, we report the isolation of a stable, five-coordinate, neutral square pyramidal Cu(III) complex that gives CH3-CF3 in quantitative yield via reductive elimination. Mechanistic studies suggest that the reaction occurs through a synchronous bond-breaking/bond-forming process via a three-membered ring transition state.

Spectroscopic, EPR, X-ray structural, and DFT studies of the complex compound of N4-donor ligand with copper(II)

A new mononuclear neutral five-coordinate copper(II) coordination compound [Cu(L)(H2O)] (1) (L = 6,6′-bis(NH-benzimidazol-2-yl)-2,2′-bipyridine) was synthesized and characterized by IR, UV–Vis, EPR and LC-MS (APCI) analysis. The crystal structure was also determined by X-ray crystallography. In 1, the copper(II) center adopts a five-coordinate distorted square-pyramidal (SP) geometry in which the basal plane formed by four of the nitrogen atoms of the ligand while the apical position is occupied by the oxygen atom of the water molecule. The four Cu–N bond lengths are 1.987(4), 1.992(4), 2.020(5) and 2.027(4) Å, and the longest bond of the apical Cu−Ow is 2.234(4) Å. The ligand undergoes deprotonation upon coordination to the metal center and acts as a dianionic tetradentate chelate to form a neutral complex [CuN4O]. The X-band EPR data of 1 are in agreement with the crystallographic data indicating a typical five-coordinate SP geometry. This geometry is also obtained by Density Functional Theory calculations. Time-dependent (TD) DFT calculations were used to shed light on the assignment and the nature of the electronic transitions observed in the UV–Vis spectrum. The calculated results are found to be consistent with the experimental data. Non-linear optical properties were also calculated by DFT calculations.

CuII -Catalyzed Oxidative Formation of 5-Alkynyltriazoles.

In an alcoholic solvent under the catalysis of Cu(OAc)2 ⋅H2 O, organic azide and terminal alkyne could oxidatively couple to afford 5-alkynyl-1,2,3-triazole (alkynyltriazole) at room temperature under an atmosphere of O2 in a few hours. The involvement of 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) is essential, without which the redox neutral coupling instead proceeds to produce 5-H-1,2,3-triazole (protiotriazole) as the major product. Therefore, DBN switches the redox neutral coupling between terminal alkyne and organic azide, the copper-catalyzed "click" reaction to afford protiotriazole, to an oxidation reaction that results in alkynyltriazole. The organic base DBN is effective in accelerating the copper(II)-catalyzed oxidation of terminal alkyne or copper(I) acetylide, which is intercepted by an organic azide to produce alkynyltriazole. The proposed mechanistic model suggests that the selectivity between alkynyl- and protiotriazole, and other acetylide or triazolide oxidation products is determined by the competition between copper(I)-catalyzed redox neutral cycloaddition and copper(II)/O2 -mediated acetylide oxidation after the formation of copper(I) acetylide.

Influence of agro-industrial wastes on the sorption, desorption, and distribution of copper in soils polluted by mine tailings

The objective of this work was to modify minimally two agro-industrial wastes, to evaluate their effectiveness for the retention of copper in soils contaminated by mining tailings, as well as to evaluate the changes in the chemical forms of the metal in the soil and thus also evaluate the attenuation of copper desorption in a short period after a mine tailing spill on the soil. The solid wastes of olive mill and grape stalks of the wine-making process were modified minimally, through washing processes and partial alkalization, to obtain substrates with greater capacity for copper sorption. Two agricultural soils near a tailing impoundment were studied: a sandy loam soil with pH close to neutral and high total and available copper content and a clay soil with low copper content, slightly acid pH, and high clay content. Both soils were treated with mine tailings from the same site to simulate an involuntary spill of mining waste. The contaminated soils were treated with the organic amendments to study the sorption, desorption, and distribution of Cu in a period of 30 days. The application of simple procedures such as alkalinization or washing of the agro-industrial wastes improved the Cu sorption capacity and facilitated the application of these materials to the soil. The application of mine tailings to the soils decreased the Cu sorption and the affinity of the substrate for the metal. This adverse effect was ameliorated by the incorporation of minimally treated olive mill wastes and grape stalks, increasing the sorption by a range of 15 to 75% compared to untreated soils. In substrates with sandy loam soil, both amendments decrease the soluble fraction of Cu, an effect that was not observed in clay soil. In parallel, both amendments increased the fraction of metal bound to the oxidizable fraction, an effect that was greater for grape stalks. The organic amendments used in this study were effective to reduce the initial contamination by copper after a spill of mine tailing wastes containing this metal. In this sense, both amendments applied to sandy loam soil increased the organic matter content and the Cu sorption capacity, effects that are maintained for at least 30 days. In clay soil, these effects were observed only for grape stalks, probably due to its greater metal sorbent capacity compared to the olive oil waste.

Decomposition of Copper Formate Clusters: Insight into Elementary Steps of Calcination and Carbon Dioxide Activation.

The decomposition of copper formate clusters is investigated in the gas phase by infrared multiple photon dissociation of Cu(II)n(HCO2)2n+1 −, n≤8. In combination with quantum chemical calculations and reactivity measurements using oxygen, elementary steps of the decomposition of copper formate are characterized, which play a key role during calcination as well as for the function of copper hydride based catalysts. The decomposition of larger clusters (n >2) takes place exclusively by the sequential loss of neutral copper formate units Cu(II)(HCO2)2 or Cu(II)2(HCO2)4, leading to clusters with n=1 or n=2. Only for these small clusters, redox reactions are observed as discussed in detail previously, including the formation of formic acid or loss of hydrogen atoms, leading to a variety of Cu(I) complexes. The stoichiometric monovalent copper formate clusters Cu(I)m(HCO2)m+1 −, (m=1,2) decompose exclusively by decarboxylation, leading towards copper hydrides in oxidation state +I. Copper oxide centers are obtained via reactions of molecular oxygen with copper hydride centers, species containing carbon dioxide radical anions as ligands or a Cu(0) center. However, stoichiometric copper(I) and copper(II) formate Cu(I)(HCO2)2 − and Cu(II)(HCO2)3 −, respectively, is unreactive towards oxygen.

Synthesis, structures and luminescent properties of red emissive neutral copper(I) complexes with bisphosphino-substituted benzimidazole

Three neutral copper(I) complexes have been synthesized and characterized, based on two iminephosphine P∧N∧P and P∧N ligands. X-ray crystallographic analysis reveals that the Cu(I) centers are chelated by the tridentate or bidentate ligands, forming distorted tetrahedron configurations. All the complexes show red emissions in powder at 293 K with moderate luminescent quantum yields of 11.8%, 1.2% and 16.6% for CuL1I, CuL1Br and (CuL2I)2, respectively. CuL1I exhibits very good thermal stability, so vapor deposited OLED based on CuL1I has been fabricated. The device displays pure red emission at 645 nm with a maximal luminance of 1970 cd m−2 and a maximum EQE of 2.68%.