Cu-O Bond Research Articles

Low-Temperature H2 Reduction of Copper Oxide Subnanoparticles.

Subnanoparticles (SNPs) with sizes of approximately 1 nm are attractive for enhancing the catalytic performance of transition metals and their oxides. Such SNPs are of particular interest as redox-active catalysts in selective oxidation reactions. However, the electronic states and oxophilicity of copper oxide SNPs are still a subject of debate in terms of their redox properties during oxidation reactions for hydrocarbons. In this work, in situ X-ray absorption fine structure (XAFS) measurements of Cu28 Ox SNPs, which were prepared by using a dendritic phenylazomethine template, during temperature-programmed reduction (TPR) with H2 achieved lowering of the temperature (T50 =138 °C) reported thus far for the CuII →CuI reduction reaction because of Cu-O bond elongation in the ultrasmall copper oxide particles.

Band gap reduction and quenching of p-d exchange interaction in sol-gel derived Zn(Al,Cu)O nanostructures

The objective of the present study is to address the gap in the fundamental knowledge on the effect of doping and co-doping in ZnO nanostructures. In this regard, we explore the significant impact of Al- and Cu co-doping on band-gap and associated changes in the ZnO system. Sol-gel co-precipitation was used to synthesize ZnO-based nanostructures to accomplish the objective. Crystallite size determined by XRD was in the range of 6.44-37.58 nm and the lattice constant, c, initially decreased with co-doping, accompanied by an increase. Strong co-doping with Cu altered the nature of microstrain from tensile to compressive. FTIR studies predicted that Al and Cu were incorporated at Zn-O site through the formation of Al-O and Cu-O bonds, while UV-vis studies suggested the reduction of the band-gap when Al and Cu were incorporated in ZnO. The underlying reason was Cu-3d and O-2p exchange interaction in Zn(Al,Cu)O system. Quenching of this exchange interaction occurred in the presence of specific combination of dopant and co-dopant, along with blocking of the low energy transitions, eventually leading to a band-gap slightly greater than undoped ZnO. Furthermore, the emission peak observed in the photoluminescence spectra implied redshift induced by Al-doping, which was not influenced on Cu co-doping. Another important observation was the presence of ferromagnetic character in all samples, where saturation magnetization decreased with the increase in Al and Cu content in ZnO matrix, a behaviour attributed to anti-ferromagnetic coupling of spins of Cu ions at the substitutional sites of Zn-O. Lastly, electron microscopy revealed that the morphology of undoped ZnO transformed from granular to sand-rose on doping with Al, while Cu co-doping led to the formation of heavy clusters. The new insights on the band-gap reduction and associated structural changes in doped ZnO-based nanostructured materials have the potential for next generation of spintronic devices.

Controllable drilling by corrosive Cu1Ox to access highly accessible single-site catalysts for bacterial disinfection

Precise modulation of local structure will improve the catalytic performance for single-site catalysts (SSCs), by taming electronic structure of supported metals and impacting the adsorption energy of reaction intermediates. In order to modify and strengthen the metal-support interaction, a controllable drilling process induced by atomic Cu1Ox is presented for fabrication of accessible SSCs. First, the bulk Cu2O was thermally driven to migrate and diffuse within the tangent graphene oxide membranes (GOM) interface, drilling plenty of channels in the GOM. Then, the volatile and atomic Cu1Ox species would diffuse through the corroded channels. At last, the Cu1Ox species with strong causticity would corrode the C-N support by breaking the Cu-O bonds and releasing CO2. Hence, the atomic Cu species were eventually anchored in the C-N support by coordination with dangling N-rich defects, forming the Cu SSCs. The fabricated Cu SSCs exhibited an excellent performance in sterilizing bacteria. As our results displayed, Escherichia coli (E. coli.) was almost sterilized by Cu SSCs via activating persulfate. Compared to the traditional approaches employed by wastewater treatment plant, our Cu SSCs exhibit much better antibacterial effect, holding a great potential for practical bacterial disinfection.

Lazaraskeite, Cu(C2H3O3)2, the first organic mineral containing glycolate, from the Santa Catalina Mountains, Tucson, Arizona, U.S.A.

Abstract A new organic mineral species, lazaraskeite, ideally Cu(C2H3O3)2 with two polytypes M1 and M2, was discovered in the high elevation of the Santa Catalina Mountains, north of Tucson, Arizona, U.S.A. Both lazaraskeite-M1 and -M2 occur as euhedral individual crystals (up to 0.20 × 0.20 × 0.80 mm) or aggregates, with the former being more equant crystals and the latter bladed crystals elongated along the c axis. Associated minerals include chrysocolla, malachite, wulfenite, mimetite, hydroxylpyromorphite, hematite, microcline, muscovite, and quartz. Both polytypes are greenish-blue in transmitted light, transparent with white streak, and a vitreous luster. They are brittle and have a Mohs hardness of ~2; cleavage is perfect on {101}. No parting or twinning was observed. The measured and calculated densities are 2.12(2) and 2.138 g/cm3, respectively, for lazaraskeite-M1 and 2.10(2) and 2.086 g/cm3 for lazaraskeite-M2. Optically, lazaraskeite-M1 is biaxial (−), with α = 1.595(3), β = 1.629(8), γ = 1.645(5), 2Vmeas = 69(2)°, 2Vcal = 67°. Lazaraskeite-M2 is also biaxial (−), with α = 1.520(5), β = 1.578(6), γ = 1.610(5), 2Vmeas = 73(2)°, 2Vcal = 70°. Lazaraskeite is insoluble in water or acetone. An electron microprobe analysis for Cu and an Elemental Combustion System equipped with mass spectrometry for C yielded an empirical formula, based on 6 O apfu, Cu1.01(C1.99H2.99O3)2 for lazaraskeite-M1 and Cu1.01(C1.98H3.00O3)2 for lazaraskeite-M2. The measured δ13C ‰ values are –37.7(1) and –37.8(1) for lazaraskeite-M1 and -M2, respectively. Both lazaraskeite-M1 and -M2 are monoclinic with the same space group P21/n. The unit-cell parameters are a = 5.1049(2), b = 8.6742(4), c = 7.7566(3) Å, β = 106.834(2)°, V = 328.75(2) Å3 for M1 and a = 5.1977(3), b = 7.4338(4), c = 8.8091(4) Å, β = 101.418(2)°, V = 333.64(3) Å3 for M2. Lazaraskeite-M1 is the natural analog of synthetic bis(glycolato)copper(II), Cu(C2H3O3)2. Its crystal structure is characterized by layers made of octahedrally coordinated Cu2+ cations and glycolate (C2H3O3)– anionic groups. These layers, parallel to (101), are linked together by the strong hydrogen bonds (O-H···O = 2.58 Å). The CuO6 octahedron is highly distorted, with four equatorial Cu-O bonds between 1.92 and 1.94 Å and two axial bonds at 2.54 Å. Lazaraskeite-M2 has the same topology as lazaraskeite-M1 and possesses all structural features of the low-temperature phase transformed from lazaraskeite-M1 at 220 K (Yoneyama et al. 2013). The major differences between the two polytypes of lazaraskeite include: (1) M1 has b > c, with β = 106.8°, whereas M2 has b < c, with β = 101.4°; (2) the CuO6 octahedron in M1 is more elongated and distorted than in M2; and (3) there is a relative change in the molecular orientation between the two structures. Lazaraskeite represents the first organic mineral that contains glycolate. Not only does its discovery imply that more glycolate minerals may be found, but also suggests that glycolate minerals may serve as a potential storage for biologically fixed carbon.

Selective Etching Quaternary MAX Phase toward Single Atom Copper Immobilized MXene (Ti3C2Clx) for Efficient CO2 Electroreduction to Methanol.

Single atom catalysts possess attractive electrocatalytic activities for various chemical reactions owing to their favorable geometric and electronic structures compared to the bulk counterparts. Herein, we demonstrate an efficient approach to producing single atom copper immobilized MXene for electrocatalytic CO2 reduction to methanol via selective etching of hybrid A layers (Al and Cu) in quaternary MAX phases (Ti3(Al1-xCux)C2) due to the different saturated vapor pressures of Al- and Cu-containing products. After selective etching of Al in the hybrid A layers, Cu atoms are well-preserved and simultaneously immobilized onto the resultant MXene with dominant surface functional group (Clx) on the outmost Ti layers (denoted as Ti3C2Clx) via Cu-O bonds. Consequently, the as-prepared single atom Cu catalyst exhibits a high Faradaic efficiency value of 59.1% to produce CH3OH and shows good electrocatalytic stability. On the basis of synchrotron-based X-ray absorption spectroscopy analysis and density functional theory calculations, the single atom Cu with unsaturated electronic structure (Cuδ+, 0 < δ < 2) delivers a low energy barrier for the rate-determining step (conversion of HCOOH* to absorbed CHO* intermediate), which is responsible for the efficient electrocatalytic CO2 reduction to CH3OH.

Equilibrium Cu isotope fractionation in copper minerals: a first-principles study

Copper is of importance in geosciences, biosciences, and industry. Its isotopes can be used to study planetary processes, trace Cu biogeochemical cycling, identify the type of Cu-bearing ore minerals, investigate the formation of ore deposits, and explore concealed ore-bodies. However, Cu isotope fractionation parameters of the majority of copper minerals remain poorly known, impeding the application of Cu isotopes as a geochemical tracer. In this study, the first-principles methods are used to compute Cu isotope fractionation parameters of chalcocite (Cu2S), covellite (CuS), villamaninite (CuS2), chalcopyrite (CuFeS2), cubanite (CuFe2S3), bornite (Cu5FeS4), cuprite (Cu2O), malachite (Cu2(CO3)(OH)2), azurite (Cu3(CO3)2(OH)2), antlerite (Cu3(SO4)(OH)4), brochantite (Cu4(SO4)(OH)6), liebauite (Ca3Cu5Si9O26), Cu-bearing enstatite (Mg31/16Cu1/16Si2O6), and native copper (Cu). The reduced partition function ratio of 65Cu/63Cu (103 ln β65−63) decreases in the order of Cu silicates > Cu carbonates > Cu sulfates > Cu oxide > native Cu > Cu sulfides. The103 ln β65−63values of these minerals display a weak correlation with oxidation state and Cu coordination number, while display a strong correlation with the average Cu-S bond lengths in Cu sulfides and the average Cu-O bond lengths in Cu oxysalt minerals with the same Cu coordination number. For Cu2S and Cu5FeS4 polymorphs, the extent of Cu isotope fractionation arising from polymorphic transformations is different. Our calculated results are useful for understanding the enrichment of Cu isotopes in nature. Cu isotope fractionation between sulfides and silicates may be a potential geothermometer.

Formation of a penta- or hexacoordinated Cu−(II) semicarbazone complex: Revisiting semicarbazone metal complexes

The structural characterization of a new pentacoordinated semicarbazone copper complex, [Cu(N,N',O-HSCPy)(N,N'-HSCPy)][ClO4]2 (1) is reported. The structure of 1 was compared to the hexacoordinated complex, [Cu(N,N',O-HSCPy)2][ClO4]2⋅H2O (2), which was already published, to shed some light on the formation of both forms. Energetic data of Cu-ligand bonds showed that the absence of a Cu-O bond in cation 1 does not significantly change the total stabilization energy in the pentacoordinate cation relative to the hexacoordinate cation (less than 4%). This is because the Cu-ligand bonds have their energies redistributed into the five existing bonds of 1. Additionally, we extended the study revisiting analogous HSCPy complexes with other coordinated metals (M), with general formula [M(N,N',O-HSCPy)2][X]2⋅solvent, where M = Ni (3), Co (4), Zn (5), Fe (6), and Mn (7); X = ClO4, and solvent = H2O (3-6) or EtOH (7); and complex [Cu(N,N',O-HSCPy)2][ClO4][I3] (8) was included in this series. In general, all additional complexes showed similar behavior to that of the Cu-hexacoordinated complex (2). In this sense, was possible to observe that the energies of the bonds M-O and M-N have strong linear correlation in the three groups: M-O3′//M-O3, M-N1′//M-N1, and M-N2′//M-N2, for complexes 2-7 (r = 0.9766; N = 18). Also, a strong correlation between stabilization energy data of metal-ligand and their respective bond lengths (r =0.9393; N = 47) was observed in all studied complexes (1-8). The supramolecular geometric similarity index ID was calculated comparing 2 with 1, 3-8. It was observed a high geometric similarity between 2 and 3-6 (ID < 0.95), indicating an isostructural behavior. The comparison between 2 and complexes 1,8 indicated values in the intermediate region (ID = 0.75) and close to a border region with an intermediate-to-high region of similarity (ID = 0.83), respectively. The similarity comparison between 2 and 7 had a value of 0.77, in the intermediate region of similarity, showing that the change of a water molecule for an ethanol molecule considerably affected the crystal packing.

Green Synthesis and Characterization of CuO Nanoparticles Derived from Papaya Peel Extract for the Photocatalytic Degradation of Palm Oil Mill Effluent (POME)

In recent years, the green chemistry based-approach for the synthesis of nanoparticles has shown tremendous promise as an alternative to the costly and environmentally unfriendly chemically synthesized nanoparticles. In this study, copper oxide nanoparticles (CuO NPs) were synthesized through a green approach using the water extract of papaya (Carica papaya L.) peel biowaste as reducing as well as stabilizing agents, and copper (II) nitrate trihydrate salt as a precursor. The structural properties, crystallinity, purity, morphology, and the chemical composition of as-synthesized CuO NPs were analyzed using different analytical methods. The analytical results revealed that the synthesized CuO was observed as spherical-like in particles with measured sizes ranging from 85–140 nm and has monoclinic crystalline phase with good purity. The Fourier transform infrared (FTIR) spectroscopic results confirmed the formation of the Cu-O bond through the involvement of the potential functional groups of biomolecules in papaya peel extract. Regarding photocatalytic activity, the green-synthesized CuO NPs were employed as a photocatalyst for the degradation of palm oil mill effluent (POME) beneath the ultraviolet (UV) light and results showed 66% degradation of the POME was achieved after 3 h exposure to UV irradiation. The phytotoxicity experiment using mung bean (Vigna radiata L.) seed also showed a reduction of toxicity after photodegradation.

Effect of Cu co-doping on the microstructure and optical properties of alumino-zinc thin films for optoelectronic applications

The effect of copper (Cu) co-doping on the microstructure and optical properties of zinc aluminate (AZO) thin films has been investigated. The micro-structure of prepared (Cu/AZO) thin films were described by X-ray diffraction (XRD), Fourier transform-infrared (FTIR), and scanning electron microscopy (HR/SEM). The optical properties are studied via UV-Vis spectrophotometry system. The XRD shows a cubic crystalline phase of the pure film and the addition of Cu did not change the cubic structure in the doped films. The vibrational bands due to the Cu-O bond have been observed at 415 cm−1-851 cm−1 in the FTIR spectra of Cu/AZO films. HR-SEM shows that both pure and doped films are quite homogeneous with good connectivity and the grain boundaries increase with increasing Cu which leads to enhancement of densification and the crystallinity of the films. Optical investigations of Cu/AZO films show a decrease in the bandgap values from 3.87 eV to 3.83 eV with increasing of Cu contents.

Synthesis, Structure, Magnetic and Catalytic Competency of a Tetradentate (NNOO) Schiff Base Mediated Dimeric Copper(II) Complex

One dinuclear copper(II) complex {μ-[2,2′-{ethane-1,2-diylbis[(azanylylidene)methanylylidene]}- bis(phenolato)]}-{μ-[2,2′-{ethane-1,2-diylbis[(azanylylidene)methanylylidene]}bis(phenolato)]}- dicopper(II), [Cu2(salen)2] (1) [salen2− = [2,2′-{ethane-1,2-diylbis[(azanylylidene)methanylylidene]}- bis(phenolato)] has been isolated and characterized by X-ray diffraction analysis and spectroscopic studies. X-ray single crystal structure examination revealed that each Cu(II) center in the asymmetric unit of 1 adopts a distorted square planar geometry with a CuN2O2 chromophore, where two asymmetric units are attached through congregation of Salen involving Cu-O bond to form dinuclear molecular unit [Cu2(salen)2]. In crystalline state, these dinuclear entities in 1 are extended through C-H···π interactions and π···π interactions displaying a 3D network structure. The variable-temperature magnetic susceptibility measurement asserted a dominant antiferromagnetic interaction between the copper(II) centers through Cu-O-Cu linkage in 1 with J = -1.46 cm-1. The catalytic efficacy of complex 1 was studied in a series of solvents for the oxidation of styrene and cyclooctene using tert-butyl-hydroperoxide (TBHP) as an active oxidant under mild conditions. The catalytic reaction mixture has been analyzed by gas chromatography and it displayed that the yield of the epoxidation and its selectivity is optimum in acetonitrile medium.

DFT Studies of the Toxicity of Para-Substituted Ortho-Benzoquinones

Toxicity descriptors based on Cu(II) coordination ability of para-substituted ortho-benzoquinones and subsequent O → Cu electron density transfer are introduced. Geometries of quinones and of their Cu(II) complexes are optimized using DFT treatment. The transferred electron density is evaluated using the copper charge or the Laplacian of electron density at the Cu-O bond critical points. The toxicity of quinones with electron-withdrawing substituents is much more sensitive to the extent of electron density transfer. Quinone O atoms exhibit equal trends for electron-donating substituents only.

First-Principles Study of Structure and Magnetism in Copper(II)-Containing Hybrid Perovskites

We report a first-principles study of hybrid organic–inorganic perovskites with formula [A]Cu(H2POO)3 (A = triazolium (Trz) and guanidinium (Gua), and H2POO− = hypophosphite), and [HIm]Cu(HCO2)3 (HIm = imidazolium cation, HCO2− = formate). The triazolium hypophosphite and the formate have been suggested as possible ferroelectrics. We study the fully relaxed structures with different magnetic orderings and possible phonon instabilities. For the [Trz]Cu hypophosphite, the Trz cation is shown to induce large octahedral distortions due to the Jahn-Teller effect, with Cu-O long-bond ordering along two perpendicular directions, which is correlated with antiferromagnetic ordering and strongly one-dimensional. We find that the structure is dynamically stable with respect to zone-center distortions, but instabilities appear along high symmetry lines in the Brillouin zone. On the other hand, for the [HIm]Cu formate, large octahedral distortions are found, with large Cu-O bonds present in half of the octahedra, in this case along a single direction, and correspondingly, the magnetism is almost two-dimensional.

Isomerism, conformation, and structure of Bis(4,4-dimethyl-1-phenylpentane-1,3-dionato)copper(II); A theoretical and spectroscopy approach

Cis and trans isomerism, conformers, molecular structure, relative energies, spectroscopic analysis, metal-ligand strength, and complete vibrational assignment of bis(4,4-dimethyl-1-phenylpentane-1,3-dionato) copper (II), Cu(dmpd)2, were investigated by applying calculated parameters such as density functional theory (DFT), Atoms in Molecules (AIM) study at the B3LYP/6-311G(d) level of theory and experimental techniques contains of vibrational spectra and UV spectroscopy. A comprehensive assignment of the experimental bands of Cu(dmpd)2 has been done. The DFT and spectroscopy techniques applied to consider the assessment of methyl and phenyl and t-But substituents in the β-position on the geometrical and vibrational analysis of complexes. So, the structure, Cu-O strength of the complex, UV spectrum, and vibrational bands of Cu(dmpd)2 compared to bis(benzoylacetonato) copper (II), Cu(bzac)2 and bis(2,2,6,6-tetramethylheptane-3,5-dionato)copper(II), Cu(tmhd)2, by the mentioned theoretical and experimental techniques. All of the simulated and spectroscopic methods supported that the Cu-O bond strength of Cu(dmpd)2is closeto Cu(bzac)2 and more than that Cu(tmhd)2 complex. Comparing the experimental and theoretical vibrational wavenumbers indicates that the transform is the major configuration in the specimen, which agrees with reported the single crystallography results.

Rational design and preparation of copper vanadate anchored on sulfur doped reduced graphene oxide nanocomposite for electrochemical sensing of antiandrogen drug nilutamide using flexible electrodes

Copper vanadate nanoparticles (Cu2V2O7) are synthesized by using a simple hydrothermal method and later anchored with sulfur-doped reduced graphene oxide (S-rGO) by using ultrasonication to form a hybrid nanocomposite. The synthesized composite underwent characterizations like X-ray diffraction analysis (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), Dynamic ray scattering-Ultra violet–visible spectroscopy (DRS-UV–visible) and X-ray photoelectron spectroscopically revealed the triclinic pattern of the P 1̅ space group of α-Cu2V2O7 and the reduced oxygen deficiency state of metal centers (Cu+ or V4+) resulting with oxides of mixed-valence oxidative states and forming of Cu-O bond. Morphological analysis was carried out by using transmission electron microscopy (TEM) and Field emission scanning electron microscopy (FE-SEM) with elemental mapping and EDX analysis. Furthermore, a novel electrochemical sensor is prepared by using the hybrid sCu2V2O7/S-rGO nanocomposite on to a disposable screen-printed carbon paste electrode (SPCE) for electrochemical sensing of antiandrogen drug nilutamide (NLT). This report reveals excellent activity in determining NLT with a low detection limit of 0.00459 nM for the linear range of 0.001–15 μM with high sensitivity of 26.2605 µA µM−1 cm−2. Further, electrode performance showed appreciable performance in real-time monitoring of biological samples like human blood serum, urine samples.

Ground-state phase diagram of the three-band Hubbard model from density matrix embedding theory

We determine the ground-state phase diagram of the three-band Hubbard model across a range of model parameters using density matrix embedding theory. We study the atomic-scale nature of the antiferromagnetic (AFM) and superconducting (SC) orders, explicitly including the oxygen degrees of freedom. All parametrizations of the model display AFM and SC phases, but the decay of AFM order with doping is too slow compared to the experimental phase diagram, and further, coexistence of AFM and SC orders occurs in all parameter sets. The local magnetic moment localizes entirely at the copper sites. The magnetic phase diagram is particularly sensitive to $\Delta_{pd}$ and $t_{pp}$, and existing estimates of the charge transfer gap $\Delta_{pd}$ appear too large in so-called minimal model parametrizations. The electron-doped side of the phase diagram is qualitatively distinct from hole-doped side and we find an unusual two-peak structure in the SC in the full model parametrization. Examining the SC order at the atomic scale, within the larger scale $d_{x^2 - y^2}$-wave SC pairing order between Cu-Cu and O-O, we also observe a local $p_{x (y)}$ [or $d_{xz (yz)}$]-symmetry modulation of the pair density on the Cu-O bonds. Our work highlights some of the features that arise in a three-band versus one-band picture, the role of the oxygen degrees of freedom in new kinds of atomic-scale SC orders, and the necessity of re-evaluating current parametrizations of the three-band Hubbard model.

Photocatalytic, antiproliferative and antimicrobial properties of copper nanoparticles synthesized using Manilkara zapota leaf extract: A photodynamic approach

Copper nanoparticles were synthesized using Manilkara zapota leaf extract. The synthesis of the nanoparticle was primarily visualized when the colour of the reaction mixture turned into reddish-brown. Biosynthesized nanoparticles were characterized by UV-vis, FT-IR, XRD, SEM and EDX. The UV spectra showed maximum absorption at 584 nm. FT-IR studies showed stretching frequency at 592.76 cm-1, which is the fingerprint region for Cu-O bond. The crystallinity of the synthesized copper nanoparticles (Mz-Cu NPs) was revealed through XRD analysis. The synthesized Mz-Cu NPs were spherical with an average size of 18.9-42.5 nm and it was shown by SEM analysis. EDX analysis displayed that the nano sample contains 58 % of copper. The antimicrobial property of the synthesized nanoparticles was evaluated against fungal plant pathogens Rhizoctonia solani (MTCC 12232), Sclerotium oryzae (MTCC 12230) and bacterial species, namely Bacillus subtilis (ATCC 23857), Escherichia coli (ATCC 25922), Staphylococcus aureus (ATCC 25923), Vibrio harveyi (ATCC 35084), Vibrio parahaemolyticus (ATCC 33845). In in-vitro haemolytic assay, the particle showed 5.73, 3.34, 0.5 % hemolysis at 100, 50, 25 μg/mL concentration respectively. In the antiproliferative assay, the IC50 values of MCF7 and Vero cells were found to be 53.89 and 883.69 μg/μl. The particle degraded Methyl violet, Malachite green and Coomassie brilliant blue by 92.2, 94.9 and 78.8 %, within 50, 40 and 60 min, respectively, through its photocatalytic activity.

Oxidopolyborate chemistry: The self-assembled, templated, synthesis, and an XRD study of a 1-D coordination polymer, [Cu(en){B6O7(OH)6}].3H2O (en = 1,2-diaminoethane)

[Cu(en){B6O7(OH)6}].3H2O (1) (en = 1,2-diaminoethane), obtained as a crystalline solid in low yield (31%) after prolonged standing of an aqueous solution initially containing [Cu(en)2](OH)2 and B(OH)3 (1:7 ratio), was characterized by thermal analysis (TGA/DSC), 11B NMR and IR spectroscopy, powder XRD, and single-crystal XRD studies, and magnetic susceptibility measurements. The single-crystal X-ray diffraction revealed that the oxidoborate complex is a 1D coordination polymer with the hexaborate(2-) ligand bridging two hexacoordinate Cu(II) centers, in an alternating a fac-tridentate (κ3-O) and monodentate (κ1-O) arrangement. Cu-O coordination bonds and extensive H-bonding networks promote and stabilize the self-assembly of [Cu(en){B6O7(OH)6}].3H2O from the Dynamic Combinatorial Libraries of available reactants. [Cu(en){B6O7(OH)6}].3H2O is thermally decomposed to CuB6O10 in air at 700 °C.

Speciation of Zn and Cu in Technosol and evaluation of a sequential extraction procedure using XAS, XRD and SEM-EDX analyses.

Metal speciation, linked directly to bioaccessibility and lability, is a key to be considered when assessing associated human and environmental health risks originated from anthropogenic activities. To identify the Zn and Cu speciation in the highly contaminated, technogenically transformed soils (Technosol) from the impact zone near the industrial sludge reservoirs of chemical plant (Siverskyi Donets River floodplain, southern Russia), the validity of the BCR sequential extraction procedure using the X-ray absorption fine-structure and X-ray powder diffraction (XRD) analyses was examined after each of the three stages. After the removal of exchange and carbonate-bonded Zn and Cu compounds from Technosol (first stage of extraction), the resulting residual soil showed enrichment in a great diversity of metal compounds, primarily with Me-S and Me-O bonds. The number of compounds with a higher solubility decreased at the subsequent stages of extraction. In the residual soil left over after extracting the first and second fractions, the dominant Zn-S bond appeared as würtzite (hexagonal ZnS) that made up more than 50%, while the Cu-S bond was almost completely represented only by chalcocite (Cu2S). The XRD analysis revealed the authigenic minerals of metals with S: sphalerite (cubic ZnS), würtzite (hexagonal ZnS), covellite (CuS) and bornite (Cu5FeS4). The scanning electron microscopy data confirmed that würtzite was the dominant form of Me with sulfur-containing and carbonate-containing minerals. The Zn-S bond was the main component (57%), whereas the Cu-O bond was dominant in the residual fraction (the fraction after the third-stage extraction). The results revealed that the composition of the residual fractions might include some of the most stable and hard-to-recover metal compounds of technogenic origin. Thus, the application of the novel instrumental methods, coupled with the chemical fractionation, revealed the incomplete selectivity of the extractants in the extraction of Zn and Cu in long-term highly contaminated soils.

Synthesis and Characterization of CuO-ZnO Nano Additive for Lubricant

A mixed metal oxide (CuO-ZnO) additives has been successfully synthesized in laboratory by co-precipitation technique. The optimum ratio of CuO and ZnO in mixed metal oxide was found to be 1:1. The sodium lauryl sulfate (SLS) has been used as surfactant. The obtained material was found to be crystalline having crystalline size of 18 nm. The stretching band in FTIR spectra at around 1072 cm-1 to 750 cm-1 and around 600 cm-1 indicates the presence of Zn-O and Cu-O bonds. As prepared nano-particles have been used as nano additive in base oil to improve physio-chemical parameters of lubricants. The results revealed that the additive blended base oil (lubricant) has shown excellent lubrication properties. The higher kinematic viscosity of 33.0504 and 6.0158 at 40°C and 100°C respectively showed that as prepared additive blended lubricant is of ISO-32 category according to ISO grading system for lubricants. Similarly, viscosity index was found to be improved from 101 to 129. The pour point was found to be significantly decreased from -6°C to -24°C. So it can be used as good pour point depressant and could be used even in the extreme cold environment condition. The flash point was found to be increased from 215°C to 220°C indicating that the prepared mixed metal oxide (CuO-ZnO) acts as flash point enhancer. The copper strip corrosion rating was found to be 1b for additive indicating the non corrosive nature. The absence of moisture and pH around the neutral range 6.18 showed the additive blended lubricant is not harmful for machinery devices.

Strain or Electronic Effects? – The influence of alkali metals on the bandgap of Cu2O

Using density functional theory we studied the influence of group 1 and 11 impurities on the bandgap of Cu2O. Our results show that dopants affect the bandgap through geometric and electronic effects. Geometric effects originate from the compression of adjacent CuO bonds while electronic effects are tightly connected to changes in the ability to delocalize electrons through 2 electron 3 center bonds. Doping with alkali metals disturbs the delocalization network and therefore results in an increased bandgap. The 2 electron 3 center bonding network is restored by Au and Ag dopants or decreased doping concentrations.