Copper Atoms Research Articles

Cu(II) complexes based on benzimidazole ligands: synthesis, characterization, DFT, molecular docking & bioactivity study.

Aim: The biggest cause of cancer deaths globally was lung cancer. New cancer fighting drugs are needed due to the rising number of cancer patients and cancer cells' treatment resistance.Results: Two Cu(II) complexes, synthesized from ligands based on 2-aminomethyl benzimidazole and salicylaldehyde derivatives, were designed and evaluated for their effectiveness against A549 lung cancer. The compounds were subjected to computational calculation using Density Functional Theory (DFT) to gather information on their reactivity. Furthermore, molecular docking are utilized to simulate the interaction between the compound and the MPP-9 protein. The synthesis of the ligands and their Cu(II) metal complexes are efficient and straightforward. The complexation between copper atom and the ligand are in 1:1 ratio. The MTT assay of the compounds against A549 lung carcinoma reveals that the both Cu(II) complexes good cytotoxicity activity, in comparison to their respective ligands. The low HOMO-LUMO band gap based on the DFT calculation predicts the high reactivity of the compounds. Furthermore, the low binding energy and the numbers of interactions of the Cu(II) complexes with MMP-9 protein binding site coincide with the antiproliferative activity tested in vitro.Conclusion: The cytotoxicity studies performed for Cu(L1Br) are promising, indicating a good candidate for a future drug.

Crystal structure of a solvated dinuclear CuII complex derived from 3,3,3′,3′-tetraethyl-1,1′-(furan-2,5-dicarbonyl)bis(thiourea)

Reaction between equimolar amounts of 3,3,3′,3′-tetraethyl-1,1′-(furan-2,5-dicarbonyl)bis(thiourea) (H2L) and CuCl2·2H2O in methanol in the presence of the supporting base Et3N gave rise to a neutral dinuclear complex bis[μ-3,3,3′,3′-tetraethyl-1,1′-(furan-2,5-dicarbonyl)bis(thioureato)]dicopper(II) dichloromethane disolvate, [Cu2(C16H22N4O3S2)2]·2CH2Cl2 or [Cu2(L)2]·2CH2Cl2. The aroylbis(thioureas) are doubly deprotonated and the resulting anions {L 2–} bond to metal ions through (S,O)-chelating moieties. The copper atoms adopt a virtually cis-square-planar environment. In the crystal, adjacent [Cu2(L)2]·2CH2Cl2 units are linked into polymeric chains along the a-axis direction by intermolecular coordinative Cu...S interactions. The co-crystallized solvent molecules play a vital role in the crystal packing. In particular, weak C—Hfuran...Cl and C—Hethyl...Cl contacts consolidate the three-dimensional supramolecular architecture.

Thiolated RAFT-PISA nano-templates power on luminescent copper nanoclusters (CuNCs) for selective mercury (II) detection

In this study, we expand the scope of polymerization-induced self-assembly (PISA) by modifying one of the most prototypical copolymers derived from RAFT-mediated PISA, poly(glycerol methacrylate)-b-poly(hydroxypropyl methacrylate) (pGMA-b-pHPMA), by incorporating a comonomer with a protected thiol group-2-(acetylthio)ethyl methacrylate (AcSEMA) into the hydrophobic block. The photoinitiated synthesis of pGMA-b-p(HPMA-co-AcSEMA) was conducted in a water/ethanol mixture (60/40 v/v) to increase the solubility of AcSEMA. Thus, this modification enabled the formation of diverse polymeric nano-morphologies such as spheres, worms, and vesicles, dictated by the balance between hydrophilic and hydrophobic block ratios and the AcSEMA content. Besides, the strong metal affinity of thiol groups makes the incorporation of AcSEMA into self-assembled nanostructures a versatile platform for generating advanced hybrid materials with potential applications in biomedicine, sensing, catalysis, or water purification. As evidenced in this work, the post-hydrolysis of the thioacetate group into thiol allowed the use of polymeric nano-objects as templates to power on the luminescenece of functionalized copper nanoclusters (CuNCs). These polymeric CuNCs, composed of several to hundreds of copper atoms, exhibit remarkable red emission, positioning the synthesized hybrids as promising luminescent probes for the development of highly selective “switch-off” luminescent sensors for Hg2+ detection. This work paves the way for the design of multifunctional hybrid nanomaterials with advanced applications.

Optical and surface properties of Schiff base ligands and Cu(II) and Co(II) complexes

Objectives. To study the transition of electrons in 1,2-phenyl(4’-carboxy)benzylidene Schiff base ligand and transition metal ions, optical properties, as well as the surface chemistry of supported transition metals using diffuse reflectance spectroscopy (DRS); to study the roughness and morphology of the Schiff base ligand and its complexes using atomic force microscopy (AFM).Methods. DRS, AFM, and Fourier-transform infrared spectroscopy instruments were used to identify electron transitions, optical properties, and surface morphology in Schiff base ligands and their complexes.Results. The DRS revealed the d–d transitions and charge transfer shifts of all compounds, and helped identify the structure of the ligand. One of the optical properties studied was the energy gap calculation of the ligand and its complexes. The copper complex exhibited more semiconducting behavior with surface morphology properties such as surface roughness parameters lower than those of the ligand and the cobalt complex. This can be attributed to the smaller size of the copper atom, as well as lower electron transitions compared to the cobalt complex and the square planar bonding shape.Conclusions. In Schiff base ligands, the reflectance spectrum bands reveal three electron transitions: n→π*, π→π*, and σ→σ* transitions. In cobalt complexes, four transitions are indicated: 4A2(F)→4T1(F), 4A2(F)→4T1(P), charge transfer bands, and tetrahedral geometry. Copper complexes exhibit three transitions: 2B1g→2A1g, 2B1g→2Eg, and charge transfer bands, with a square planar geometry for their structure. The energy gap calculations were 2.42, 2.29, and 2.30 eV, respectively. In the case of the SH ligands, copper complexes, and cobalt complexes, all compounds exhibited semiconductor properties. However, the complexes displayed increased conductivity due to the influence of the metal and coordination structure.

Uncovering mechanism of excessive copper ion-activated depressed-sphalerite under moderate alkaline conditions: A combined experimental and DFT investigation

Currently, extensive research exists on the activation mechanisms of sphalerite, yet there is a notable absence of studies on the mechanisms behind the activation of depressed sphalerite. This paper investigates the mechanism through which moderate or excessive copper ions activate depressed sphalerite under conditions (pH 9–10) of moderate alkalinity, employing a comprehensive approach that includes pure mineral flotation experiments, contact angle measurements, FESEM-EDS, XPS, and density functional theory simulations.The results from pure mineral flotation experiments reveal that, at a copper ion concentration of 1 × 10−4 mol/L, sphalerite, previously depressed by zinc sulfate, is activated by copper ions, achieving a recovery rate of 91.46 % with butyl xanthate as the collector. However, when more cooper ions are added, the recovery of sphalerite decreases. Contact angle measurements and FESEM-EDS data indicate that under conditions of moderate alkalinity, zinc sulfate undergoes hydrolysis to form hydrophilic colloidal substances (hydroxylated zinc) that adhere to the surface of sphalerite, rendering it hydrophilic and thereby depressed. Following the introduction of copper ions, a dense striated material forms on the surface of sphalerite previously inhibited by zinc sulfate, enhancing its hydrophobicity, but if more copper ions were added, the hydrophobicity of activated sphalerite will be weakened. XPS findings further suggest that activated sphalerite by copper is capable of forming polysulfides, which then act on the sphalerite. DFT simulations verify that under moderate alkalinity conditions, copper ions first undergo a hydroxylation reaction in the solution before adsorbing or precipitating on the mineral surface as hydroxylated substances, which subsequently interact with sulfur on the surface of sphalerite. The analysis of the density of states indicates that following the addition of butyl xanthate, the strongest 3p orbital electron peak of the sulfur atom bound to butyl xanthate and the strongest 3d orbital electron peak of zinc are at distinct energy levels, suggesting that the overlap of the electronic density of states is minimal, indicating a weak and unstable interaction between the sulfur and zinc atoms bonded with butyl xanthate. Conversely, the strongest 3p orbital electron peak of the sulfur atom bonded with butyl xanthate overlaps with the strongest 3d orbital electron peak of copper and is positioned near the Fermi level, signifying a strong reactivity and more stable interaction between the sulfur and copper atoms.

Study on pyrolysis process and mechanism of organic coating of waste polyesterimide enameled wire based on density functional theory

The pyrolysis treatment of waste polyesterimide enameled wire offers significant advantages such as continuous processing, non-hazardous nature, and high resource recovery rate. However, research on its pyrolysis process and mechanism remains insufficiently explored. In this study, techniques including thermogravimetry (TG), Fourier transform infrared spectroscopy(FT-IR), pyrolysis–gas chromatography-mass spectrometry(Py-GC/MS) were employed to investigate pyrolysis temperature, weight loss rate, pyrolysis and kinetic parameters, composition and distribution of pyrolysis products, and changes in functional groups under different temperatures and heating rates. The pyrolysis of polyesterimide enameled wire can be divided into three stages: volatilization of specific components (314.8 °C,1.6 %), rapid decomposition of polyesterimide (435.2 °C, 44.7 %), and generation of small organic molecules with the fixation of pyrolytic carbon (750 °C, 9.0 %). The main components of the pyrolysis gas products include aromatic compounds, ethers, aromatics, ketones, and carbon dioxide. At 400 °C, a substantial amount of pyrolysis gas products and free radicals are produced, with an increase in aromatic hydrocarbons. The carbon distribution in the pyrolysis products mainly focuses on C6-C10 and C11-C15, and many organic compounds such as benzoic acid, phenol, and aniline are generated. Based on density functional theory, the bond dissociation energies in the polyesterimide were calculated. This clarified the possible thermal decomposition pathways of the polyesterimide and provided the energy barrier values, elucidating the generation mechanism of pyrolysis products during thermal decomposition. The copper atom in specific location reduces the negative ESP of O and increases the positive ESP of H in EPI, which makes H more likely to attach to O. The presence of Cu increases the ESP range and promote the pyrolysis process. This study provides a theoretical basis for the high-value recycling of waste polyesterimide enamelled wire.

Green Synthesis, Characterization, and Catalytic Applications of CuO Nanoparticles Using Prosopis Cineraria Seed Extract

Abstract The current study used a seed extract of Prosopis cineraria as a stabilizing and reducing agent to produce CuO nanoparticles via an easy, low-cost, affordable, and environmentally friendly synthesis process. The formation of copper oxide nanoparticles and the maximum absorbance of the CuO nanoparticles produced in the solution at 565 nm were verified by UV-vis. Copper oxide nanoparticles were found to have secondary metabolites on their surface, as shown by a distinctive Cu-O stretching band at 532 cm−1, which confirmed the reduced Cu2+ ions in copper oxide nanoparticles. This was confirmed by FTIR analysis. The XRD analysis confirmed the produced copper oxide nanoparticles’ monoclinic crystalline nanostructure with an average particle size of 34 nm. The phytonutrients in Prosopis cineraria seed extract stabilized and reduced copper, as demonstrated by the existence of copper and oxygen atoms at 85.2% and 12.5%, respectively, as demonstrated by SEM-EDX analysis. According to the HR-TEM study, copper oxide nanoparticles with a mean size of 18 nm are spherical in shape and well distributed. Prosopis cineraria seed extract-derived copper oxide nanoparticles were utilized as a catalyst in the Ullmann process to produce diphenyl ether. CuO nanoparticles produced by Prosopis cineraria seed extraction as a catalyst yielded 91% diphenyl ether. The results showed that a more ecologically friendly way of synthesizing copper oxide nanoparticles with great homogeneity of particle sizes could be achieved using seed extract. This work aims to facilitate heterogeneous catalysis from CuO nanoparticles utilising Prosopis cineraria seed extract. Overall, this technique offers several advantages, like high yields at fast reaction times, and low catalyst loading are just a few of this approach’s many benefits.

Effect of Surface Polymeric Organosilicon Nanolayers on the Electrochemical and Corrosion Behavior of Copper.

The formation of polymeric self-organizing organosilicon surface nanolayers on copper occuring as a result of modification of the metal surface with organosilane-based formulations has been studied. The anticorrosive effect of such surface layers in corrosive chloride-containing electrolytes as well as in artificial and natural atmospheres has been studied in detail. It has been found that the maximum protective effect is observed at a thickness of 3.8 molecular layers, where the densest cross-linked polymer layers are formed that hinder the adsorption of chloride ions and other corrosive agents on the metal surface, thus significantly reducing the rate of their reactions with the surface copper atoms, and, as a result, inhibiting the corrosion and local anodic dissolution of the metal.

Copper Atom Pairs Stabilize *OCCO Dipole Toward Highly Selective CO2 Electroreduction to C2H4

AbstractDeeply electrolytic reduction of carbon dioxide (CO2) to high‐value ethylene (C2H4) is very attractive. However, the sluggish kinetics of C−C coupling seriously results in the low selectivity of CO2 electroreduction to C2H4. Herein, we report a copper‐based polyhedron (Cu2) that features uniformly distributed and atomically precise bi‐Cu units, which can stabilize *OCCO dipole to facilitate the C−C coupling for high selective C2H4 production. The C2H4 faradaic efficiency (FE) reaches 51 % with a current density of 469.4 mA cm−2, much superior to the Cu single site catalyst (Cu SAC) (~0 %). Moreover, the Cu2 catalyst has a higher turnover frequency (TOF, ~520 h−1) compared to Cu nanoparticles (~9.42 h−1) and Cu SAC (~0.87 h−1). In situ characterizations and theoretical calculations revealed that the unique Cu2 structural configuration could optimize the dipole moments and stabilize the *OCCO adsorbate to promote the generation of C2H4.

Stable Cu (I) single copper atoms supported on porous carbon nitride nanosheets for efficient photocatalytic degradation of antibiotics

Stable Cu (I) single copper atoms supported on porous carbon nitride nanosheets for efficient photocatalytic degradation of antibiotics

Synthesis, characterization, and Hirshfeld surface analysis of coordination compounds composed of two different aminopyridines, isothiocyanate ligand molecules, and two different transition metal atoms.

In this article, we describe the successful synthesis of three coordination compounds formed by the ligands 3-aminopyridine, 4-aminopyridine, and isothiocyanate ion with copper atoms and 4-aminopyridine and isothiocyanate ion with cadmium atoms, and their structural characterizations. The crystal structures of the compounds were determined by single crystal X-ray diffraction. According to that technique, the open formulae of these compounds are [Cu(3-aminopyridine)2(NCS)2] (1), [Cu(4-aminopyridine)3(NCS)2] (2), and [Cd(4-aminopyridine)2(NCS)Cl] (3). In addition, the suitability of the structures of the compounds was characterized by elemental analysis, thermal analysis, and Fourier transform infrared spectroscopy. The single crystal X-ray diffraction analyses of these coordination compounds showed that the first of these coordination compounds had a 1D crystal structure and the other two had a 3D crystal structure. N-H⋯S, N-H⋯N, N-H⋯Cl, N-H⋯π, and C-H⋯π bonds and their combinations were effective in the formation of the crystal structures of the said coordination compounds. The metal atoms [Cu(II), Cu(II), and Cd(II)] in these coordination compounds were surrounded by various ligand molecules in a square planar, square pyramidal, and octahedral arrangement, respectively. In order to investigate some chemical and structural properties of these coordination compounds, theoretical calculations were performed with the software package Gaussian 03. The highest occupied molecular orbital (HOMO), lowest occupied molecular orbital (LUMO), and natural bond orbital (NBO) values of the coordination compounds were used in these calculations. When the energy gap value between the HOMO and LUMO states of the compounds was examined, it was predicted that compound 3 may have lower kinetic stability, higher chemical activity, and lower semiconductor properties than all the other compounds. According to the Hirshfeld surface analysis of the compounds, C⋯H, S⋯H, H⋯H, and N⋯H interactions are generally seen in the crystal structures of all compounds. In addition, Cd⋯Cl, Cd⋯S, H⋯Cl, and Cl⋯Cl interactions also occur in compound 3.

Thermal Transformations in Copper/Sodium-Organosiloxanes of a Globular Structure

The thermal and thermo-oxidative transformations in cage-like metal-organosiloxanes of the general formula [RSiO1.5]12[CuO]4[NaO0.5]4 (R= Ph, Me) were studied. It was established that their decomposition occurs in two stages and includes a number of solid-state reactions, leading to the abstraction of organic groups from the silicon atom, the partial or complete reduction of copper atoms, and the release of metallic and oxide phases.

Corrosion resistance and forming mechanism of phytic acid conversion film on copper foil prepared by electrolysis

In this paper, the phytic acid conversion film was prepared on copper foil by electrolysis for the first time. Its morphology and chemical composition were characterized by SEM, EDS, FTIR and XPS, and its corrosion resistance was evaluated using electrochemistry. Finally, the formation mechanism of the phytic acid conversion film on the surface of copper foil and its corrosion resistance mechanism were revealed by quantum chemical calculations and molecular dynamics simulations. The results show that the phytic acid conversion film on the surface of copper foil prepared by electrolysis is uniform and dense. The electrochemical impedance value of copper foil in 3.5 wt% NaCl solution increased from 3956 Ω·cm2 to 24828 Ω·cm2 after the preparation of phytic acid conversion film, and the protection efficiency reached 91 %. During the electrolysis process, copper atoms are oxidized into copper ions, which can be coordinated with phytate ions to form negatively charged complexes. Under the action of electric field force, these complexes move toward the anode copper foil, and finally adsorbed on the surface of the anode copper foil to form phytic acid conversion film. The molecular dynamics show that the adsorption configuration of the phytic acid molecule on Cu(111) surface changed from perpendicular to parallel, and the binding energy increased from 234.87 kJ/mol to 354.23 kJ/mol after applying an electric field, Therefore, the phytic acid conversion film prepared on the surface of copper foil by electrolysis has good corrosion resistance. This study provides a new method for the rapid preparation of phytic acid conversion film with excellent performance on metal surface.

Green synthesis of copper oxide nanoparticles using solanum melongena seeds extract and its applications in degradation of Rose Bengal dye, antibacterial, catalytic reduction and antioxidant activity

The generation of copper oxide (CuO) nanoparticles using a biogenic extract (solanum melongena seeds) was the primary focus of this study. As prepared catalyst has been utilized for dye degradation of Rose Bengal and studies on Antibacterial and Antioxidants. The catalyst was characterized for its structural aspects by using Scanning electron microscopy - energy dispersive spectroscopy (SEM-EDS), Powder X-ray Diffraction (PXRD), Fourier Transform - InfraRed spectroscopy (FT-IR), Thermogravimetric Analysis (TGA), Brunauer-Emmett-Teller (BET) and UV–Visible DRS. The characterization results of XRD shows that the catalyst is in monoclinic phase. Copper Oxide is irregular in morphology and the average particle size is 47.97 nm which can be obtained using the SEM images and EDS spectra shows the Oxygen and Copper atoms presence which indicates the free from impurities of the fabricated biogenic CuO nanoparticles. FT-IR result indicated the stretching frequency of Cu–O appears at 487 cm−1. TGA data reveal that high-purity and thermally stable nanoparticles were fabricated, by the absence of significant weight losses at temperatures greater than 400 °C. Through UV–Visible DRS the calculate band gap was found to be 2.8eV. Based on the characterisation results the best catalyst was used to degrade the Rose Bengal dye within 60 min and also carried out the antibacterial and antioxidant activity which was found to be satisfactory when compared with their standard values.

Anchoring Frustrated Lewis Pair Active Sites on Copper Nanoclusters for Regioselective Hydrogenation.

In recent years, the concept of Frustrated Lewis Pairs (FLPs), which consist of a combination of Lewis acid (LA) and Lewis base (LB) active sites arranged in a suitable geometric configuration, has been widely utilized in homogeneous catalytic reactions. This concept has also been extended to solid supports such as zeolites, metal oxide surfaces, and metal/covalent organic frameworks, resulting in a diverse range of heterogeneous FLP catalysts that have demonstrated notable efficiency and recyclability in activating small molecules. This study presents the successful immobilization of FLP active sites onto the surface of ligand-stabilized copper nanoclusters with atomic precision, leading to the development of copper nanocluster FLP catalysts characterized by high reactivity, stability, and selectivity. Specifically, thiol ligands containing 2-methoxyl groups were strategically designed to stabilize the surface of [Cu34S7(RS)18(PPh3)4]2+ (where RSH = 2-methoxybenzenethiol), facilitating the formation of FLPs between the surface copper atoms (LA) and ligand oxygen atoms (LB). Experimental and theoretical investigations have demonstrated that these FLPs on the cluster surface can efficiently activate H2 through a heterolytic pathway, resulting in superior catalytic performance in the hydrogenation of alkenes under mild conditions. Notably, the intricate yet precise surface coordination structures of the cluster, reminiscent of enzyme catalysts, enable the hydrogenation process to proceed with nearly 100% selectivity. This research offers valuable insights into the design of FLP catalysts with enhanced activity and selectivity by leveraging surface/interface coordination chemistry of ligand-stabilized atomically precise metal nanoclusters.

Simulation of Structural, Electronic and Pharmacodynamics Properties of Developed Zeolite Docking with Hemoglobin

The study included simulating the preparation of the structure of zeolite with its natural square structure in its simplest form, in addition to the structure of the developed zeolite, where the square zeolite was developed by adding one atom of copper or iron, in addition to the preparation of the cubic zeolite. Simulation of the structural and electronic properties of zeolite and developed zeolite structures was studied, using density functional theory at the B3LYP level and the 6 – 311G(d,p) basis set. The above properties of non-oxidized and oxidized hemoglobin were also simulated, for the purpose of making a comparison between it and the coalescence of developed zeolite with non-oxidized hemoglobin, to know the effect of the developed zeolite structures on hemoglobin as a pharmacodynamics properties. The Gibbs free energy was calculated for the docking of oxygen with non-oxidized heme, which was (-51.624 eV) as well as for the zeolite structures developed after docking with non-oxidized heme, which was (94814.14175 eV) for Fe - zeolite with DHB and (4107.871817 eV) for Cu - zeolite with DHB. Through the thermodynamic results, it was shown that the docking process of the developed zeolite structures with non-oxidized hemoglobin is non-lethal and harmless and is similar to the docking process of oxygen with heme. It can be concluded from this, that the developed zeolite structures can be used in medical applications, such as participating in treatment, delivering medications, or carrying medications inside the human body.

Simulation of Structural, Electronic and Pharmacodynamics Properties of Developed Zeolite Docking with Hemoglobin

The study included simulating the preparation of the structure of zeolite with its natural square structure in its simplest form, in addition to the structure of the developed zeolite, where the square zeolite was developed by adding one atom of copper or iron, in addition to the preparation of the cubic zeolite. Simulation of the structural and electronic properties of zeolite and developed zeolite structures was studied, using density functional theory at the B3LYP level and the 6 – 311G(d,p) basis set. The above properties of non-oxidized and oxidized hemoglobin were also simulated, for the purpose of making a comparison between it and the coalescence of developed zeolite with non-oxidized hemoglobin, to know the effect of the developed zeolite structures on hemoglobin as a pharmacodynamics properties. The Gibbs free energy was calculated for the docking of oxygen with non-oxidized heme, which was (-51.624 eV) as well as for the zeolite structures developed after docking with non-oxidized heme, which was (94814.14175 eV) for Fe - zeolite with DHB and (4107.871817 eV) for Cu - zeolite with DHB. Through the thermodynamic results, it was shown that the docking process of the developed zeolite structures with non-oxidized hemoglobin is non-lethal and harmless and is similar to the docking process of oxygen with heme. It can be concluded from this, that the developed zeolite structures can be used in medical applications, such as participating in treatment, delivering medications, or carrying medications inside the human body.

[Cu(en)2]2+ - [W(CN)6(bpy)]2- interactions in cyanido bridged and not linked complexes – structural study

Five heterobimetallic Cu(II)-W(IV) complexes with the general formulas [Cu(en)2][W(CN)6(bpy)], {[Cu(en)2][W(CN)6(bpy)]}2∙[Cu(en)2(H2O)2]X2 (where X = Cl or Br), Na4K2[Cu(en)2][W(CN)6(bpy)]4, Li2[Cu(en)2(H2O)2][W(CN)6(bpy)]2 were synthesized and described by elemental analyses, magnetic measurements, IR and UV–Vis spectra, as well as the single crystal X-ray structure measurements. In structures, the copper atoms adopt the geometry of a slightly distorted octahedron. The effect of the addition of a halogen or alkali metal on the different modes of cyanide bridging in all structures was discussed. These results provide an important contribution to the knowledge on the controllable synthesis of coordination networks based on cyanide bridges.

Synthesis, structure and optically limiting NLO properties of a distorted cubane-like cluster (µ-Cl)(µ 3-WSe4)(CuPPh3)3

Abstract Treatment of [Et4N]2[WSe4] with three equivalents of CuCl and PPh3 (Ph = phenyl) in a mixed solvent of 25 mL of CH2Cl2 and 5 mL of DMF afforded a distorted cubane-like cluster [(µ-Cl)(µ 3-WSe4)(CuPPh3)3] (1), which has been structurally characterized by single-crystal X-ray diffraction. The coordination geometry of the tungsten center and two copper atoms is tetrahedral, whereas that of the other copper atom is triangular. Regarding the NLO properties, a large optical limiting effect with a threshold of 0.91 J cm−2 was observed with laser pulses of 7 ns at 532 nm.

Copper-rich complexes in irradiated silicon

Only copper-related deep-level centers are produced by room-temperature MeV-electron irradiation in silicon doped with a high concentration of mobile interstitial copper atoms. In oxygen-lean FZ-Si, the well-known CuPL centers of four copper atoms show up in the DLTS, Laplace-DLTS, and photoluminescence measurements. In oxygen-rich Cz-Si, two new centers appear due to the irradiation at the expense of the CuPL defect. Reaction kinetics analysis correlates the new defects with oxygen, copper, and the irradiation-induced vacancy. The new defects are annealed at temperatures of 150–250 °C and, after passing through two more new configurations, are transformed into CuPL. The strong similarities to CuPL suggest that all four new defects are CuPL-like complexes of four copper atoms perturbed by a nearby oxygen.