Copper Carboxylate Research Articles

In Situ Time-of-Flight Mass Spectrometry of Ionic Fragments Induced by Focused Electron Beam Irradiation: Investigation of Electron Driven Surface Chemistry inside an SEM under High Vacuum.

Recent developments in nanoprinting using focused electron beams have created a need to develop analysis methods for the products of electron-induced fragmentation of different metalorganic compounds. The original approach used here is termed focused-electron-beam-induced mass spectrometry (FEBiMS). FEBiMS enables the investigation of the fragmentation of electron-sensitive materials during irradiation within the typical primary electron beam energy range of a scanning electron microscope (0.5 to 30 keV) and high vacuum range. The method combines a typical scanning electron microscope with an ion-extractor-coupled mass spectrometer setup collecting the charged fragments generated by the focused electron beam when impinging on the substrate material. The FEBiMS of fragments obtained during 10 keV electron irradiation of grains of silver and copper carboxylates and shows that the carboxylate ligand dissociates into many smaller volatile fragments. Furthermore, in situ FEBiMS was performed on carbonyls of ruthenium (solid) and during electron-beam-induced deposition, using tungsten carbonyl (inserted via a gas injection system). Loss of carbonyl ligands was identified as the main channel of dissociation for electron irradiation of these carbonyl compounds. The presented results clearly indicate that FEBiMS analysis can be expanded to organic, inorganic, and metal organic materials used in resist lithography, ice (cryo-)lithography, and focused-electron-beam-induced deposition and becomes, thus, a valuable versatile analysis tool to study both fundamental and process parameters in these nanotechnology fields.

Single-Step Synthesized Functionalized Copper Carboxylate Framework Meshes as Hierarchical Catalysts for Enhanced Reduction of Nitrogen-Containing Phenolic Contaminants

Nitrogen-containing phenolic contaminants (NCPCs) represent typical pollutants of industrial wastewaters. As catalytic reduction of NCPCs is a useful technique and Cu is an efficient metal catalyst, Cu-carboxylate frameworks (CuCF) are favorable materials. However, they are in powder form, making them difficult to use; thus, in this study, CuCF was grown on macroscale supports. Herein, we present a facile approach to develop such a CuCF composite by directly using a Cu mesh to grow CuCF on the mesh through a single-step electrochemical synthesis method, forming CuCF mesh (CFM). CFM could be further modified to afford CuCF mesh with amines (NH2) (CFNM), and CuCF mesh with carboxylates (COOH) (CFCM). These CuCF meshes are compared to investigate how their physical and chemical characteristics influenced their catalytic behaviors for reduction/hydrogenation of NPCPs, including nitrophenols (NPs) and dyes. Their nanostructures and surface properties influence their behaviors in catalytic reactions. In particular, CFCM appears to be the most efficient mesh for catalyzing 4-NP, with a much higher rate constant. CFCM also shows a significantly lower Ea (28.1 kJ/mol). CFCM is employed for many consecutive cycles, as well as convenient filtration-type 4-NP reduction. These CuCF meshes can also be employed for decolorization of methylene blue and methyl orange dyes via catalytic hydrogenation.

Synthesis, spectroscopic characterization, biological screening and POM analysis of potentially bioactive copper(II) carboxylate complexes

ABSTRACT. Here we are reporting the synthesis, characterization of four novel copper(II) complexes with carboxylate ligand and their evaluation for biological applications. The complexes have general formulas C22H18CuN4O12, C32H26CuN6O12, C27H23CuN5O12 and C34H26CuN6O12. The synthesized complexes were characterized by FT-IR and elemental analyses carried out through EDX. The deprotonation of the carboxylate ligand, 4-(2-methoxy-5-nitrophenylamino)-4-oxobut-2-enoic acid, was observed in FT-IR spectrum, indicating that complexation happens via the carboxylate moiety's oxygen. In complexes 1 and 3, the value of Δν value is in between 120-180 cm-1 showing the bridging mode of the carboxylate moiety while in complexes 2 and 4, its value is greater than 180 cm-1 indicating the monodentate binding mode. The findings of antimicrobial activity revealed that the complexes have adequate antibacterial and antifungal properties. The anti-promastigote analysis results showed that the complexes 1 and 4 have significant activity as compared to the standard drug. The binding mode of complexes with DNA was confirmed by UV-Visible spectroscopy and viscosity measurements and the results showed that complexes interact with DNA through intercalative mode. A new and efficient strategy was applied through POM (Petra, Osiris and Molinspiration) analyses for determining the toxicity assessment, bio-availability and drug score of the synthesized complexes. The results showed that the complexes have good bioavailability and drug scores.
 
 KEY WORDS: Copper(II) carboxylate complex, DNA binding, Anti-promastigote analysis, Cytotoxicity, POM analysis, Docking study
 Bull. Chem. Soc. Ethiop. 2022, 36(1), 57-71. 
 DOI: https://dx.doi.org/10.4314/bcse.v36i1.6

Identification of pigments used in a Qajar manuscript from Iran by using atomic and molecular spectroscopy and technical photography methods

The present study aimed to identify pigments used in writing and decorating a Qur'an manuscript related to the early years of the Qajar era, a royal dynasty ruling over Iran from 1789 to 1925. The pigments were analysed using µ-XRF, SEM–EDS, Raman, and FTIR spectroscopy. Also, various technical photography methods were used to study the pigments including visible-reflected (VIS), infrared photography (IR), ultraviolet-reflected (UVR), and ultraviolet-induced visible luminescence (UVL) along with infrared false color (IRFC) and ultraviolet false color (UVFC) methods. Carbon black, red lead, and indigo were identified as black ink, orange, and blue pigments, respectively. A mixture of red lead and vermilion was also detected in the red/orange ink. White lead and calcite were also used as additives in blue color. A cochineal-based pigment was also used as red ink in some parts of the manuscript. However, the evaluation of golden color showed two types pigments of gold and brass alloys in different parts of the manuscript. Copper carboxylate was identified as the product of the destruction of this pigment. According to the results of the study, technical photography methods along with spectroscopic methods are a good tool to examine manuscripts and identify included pigments and reduce the amount of possible error and the need for destructive sampling.

Synthesis, crystal structure and thermal stability of new copper(II) trichloroacetate complexes

We have synthesized two novel complexes of copper(II) trichloro acetate, Cu2(CCl3COO)3(OH)(H2O)4·H2O and Cu(CCl3COO)2(MeCN), and determined their crystal structures and thermal stability. While the complex with acetonitrile has a discrete binuclear paddle-wheel structure, typical of copper carboxylates, the aqua-hydroxo complex belongs to a novel unique chain–molecular type of basic copper complexes.

SYNTHESIS OF METAL CARBOXYLATES FROM ALMOND SEED OIL (TERMINALIA CATAPPA

TThe less exploited seed oil of almond was investigated for its potential utilization as a raw material for the synthesis of metal carboxylates. The oil was extracted from the almond seeds and a yield of 42% was obtained. The oil was characterized and used to synthesize the carboxylates of barium, calcium, cobalt, copper, iron, magnesium, nickel and zinc. The functional groups of fatty acid carboxylates produced were confirmed by FTIR. The characteristic colours of the carboxylates were white (barium, calcium, magnesium and zinc carboxylates), ash (Cobalt carboxylate), mint green (copper carboxylate), brown (iron carboxylate), and lemon green (nickel carboxylate). The pH of the solutions of the metal carboxylates varies from 6.6 to 10 with no free alkaline. The foam stability test revealed a length of 1.3 cm for barium carboxylate and 0.3 cm for magnesium carboxylate while other carboxylates did not foam.

Melting dislocation transition in composite lithium greases with copper(II) carboxylate mesogenic additives

abstract We propose the theory for the temperature and concentration phase transformations in composite lithium grease doped with the mesogenic additives, copper(II) carboxylates valerate and isovalerate, in the range 1, 5, 10, 20 wt. %. The changes in specific electric conductivity manifested in dielectric spectroscopy in the measuring electric field of 100 Hz – 1 MHz and polarization microscopy are reliable caused by reversible transitions from the discotic to isotropic phase or at heating from room temperature to 391 K. To define critical properties of the transitions, we applied Monte Carlo simulations using the Berezinsky-Kosterlitz-Thouless model describing screw, transverse edge and longitudinal dislocations.

Synthesis, characterization, antioxidant, antileishmanial, anticancer, DNA and theoretical SARS-CoV-2 interaction studies of copper(II) carboxylate complexes

Copper(II) carboxylate complexes [Cu2(OOCR)4L2] (1) and [Cu2(OOCR`)4OCO(R`)CuL2]n (2), where L = 2-methyl pyridine, R = 2-chlorophenyl acetate and R` = 2-fluorophenyl acetate were synthesized and characterized by FT-IR spectroscopy and single crystal X-ray analysis. Complex 1 exhibits the typical paddlewheel array of a dinuclear copper(II) complex with carboxylate ligands. In complex 2, this scaffold is further extended into a polymeric arrangement based on alternate paddlewheel and square planar moieties with distinct coordination spheres. The complexes showed better 2,2-diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radical scavenging activities and have been found to be more potent antileishmanial agents than their corresponding free ligand acid species. UV-Vis absorption titrations revealed good DNA binding abilities {Kb = 9.8 × 104 M–1 (1) and 9.9 × 104 M–1 (2)} implying partial intercalation of the complexes into DNA base pairs along with groove binding. The complexes displayed in vitro cytotoxic activity against malignant glioma U-87 (MG U87) cell lines. Computational docking studies further support complex-DNA binding by intercalation. Molecular docking investigations revealed probable interactions of the complexes with spike protein, the nucleocapsid protein of SARS-CoV-2 and with the angiotensin converting enzyme of human cells.

Synthesis of Coordination Polymers and Discrete Complexes from the Reaction of Copper(II) Carboxylates with Pyrazole: Role of Carboxylates Basicity

The reaction of select copper(II) monocarboxylates Cu(RCOO)2(H2O)x (R = C4H3O, C6H5, H; x = 2, 4) with pyrazole (Hpz), carried out in protic solvents, yields mono- or dinuclear species [Cu(RCOO)2(Hpz)n]m (n = 2, 4; m = 1, 2), always accompanied by tri- or hexanuclear derivatives based on the triangular [Cu3(μ3-OH)(μ-pz)3]2+ fragment. The molecular structures of all isolated compounds have been established through XRD determinations. In some cases, the mono-, or dinuclear species act as secondary building units, self-assembling into 1D or 3D coordination polymers. The hexanuclear benzoate cluster contains coordinated and crystallization MeOH molecules, whose removal generates a crystalline 1D coordination polymer that can be reconverted into the hexanuclear cluster by soaking in MeOH. The relatively high pKb values of carboxylate anions employed in the syntheses are responsible for the preferential formation of mono- or dinuclear species rather than tri- or hexanuclear ones.

Copper(II) Perfluorinated Carboxylate Complexes with Small Aliphatic Amines as Universal Precursors for Nanomaterial Fabrication.

Copper(II) carboxylate compounds with ethylamine and isopropylamine of the general formula [Cu2(RNH2)2(µ-O2CRf)4], where R = Et, iPr, and Rf = CnF2n+1, n = 1–6, were characterised in the condensed and gas phases by electron impact mass spectrometry (EI MS), IR spectroscopy, and thermal analysis. A mass spectra analysis confirmed the presence of metallated species in the gas phase. Among the observed fragments, the pseudomolecular ions [Cu2(RNH2)2(µ-O2CRf)3]+ were found, which suggests the dimeric structure of the studied complexes with axially N-coordinated ethyl- or isopropylamine molecules and bridging perfluorinated carboxylates. TGA studies demonstrated that copper transfer to the gas phase occurs even under atmospheric pressure. The temperature range of the [Cu2(RNH2)2(µ-O2CRf)4] and other copper carriers detection, observed in variable temperature infrared spectra, depends on the type of amine. The possible mechanisms of the decomposition of the tested compounds are proposed. The copper films were produced without additional reducing agents despite using Cu(II) CVD precursors in the chemical vapor deposition experiments. The layers of the gel-like complexes were fabricated in both spin- and dip-coating experiments, resulting in copper or copper oxide materials when heated. Dinuclear copper(II) carboxylate complexes with ethyl- and isopropylamine [Cu2(RNH2)2(µ-O2CRf)4] can be applied for the formation of metal or metal oxide materials, also in the nanoscale, by vapour and ‘wet’ deposition methods.

Centro-symmetric paddlewheel copper(II) carboxylates: Synthesis, structural description, DNA-binding and molecular docking studies

The synthesis, structural characterization and biological relevance of three paddlewheel binuclear carboxylate copper(II) complexes with the formulae [Cu2(2-nitrophenylacetate)4(H2O)2]C2H5OH (1), [Cu2(diclofenate)4(acetone)2] (2) and [Cu2(4-bromophenylacetate)4(pyridine)2] (3) have been presented here. These complexes have been characterized using melting point, FTIR, absorption spectroscopy, electron spin resonance, cyclic voltammetry (CV) and single crystal XRD techniques, while their biological relevance was ascertained using molecular docking and DNA-binding studies. The FTIR spectra indicated all the important functionalities and the typical bridging bidentate coordination mode of the carboxylate moieties to the copper ion. Absorption spectroscopy yielded broad spectra corresponding to the 2B1g ground state and the singly occupied dx2–y2 orbital, typical of the copper(II) ion. This finding was confirmed by the ESR signals of complexes 1–3, with g values of 1.44353, 1.44317 and 1.44324, respectively. CV yielded redox couples typical of complexes with Cu2+ metal centers. XRD showed that the copper(II) ions in all three complexes are coordinated by four carboxylate ligands, constituting the square base of the square pyramid around each copper ion. The apical position is occupied by water (1), acetone (2) or pyridine (3) molecules. Owing to the structural differences, 1 and 3 have inter-molecular interactions and growth along all three axes, while 2 has such interactions only along the a-axis, leading to preferential growth along this axis. The structural parameters of the structures are different from each other and have been correlated mutually as well as with their literature analogues. Their supra-molecular synthons have been presented and explained. A computational study by molecular docking using MOE (molecular operating environment) software has yielded docking scores of −8.4098, −8.0453 and −9.4098, respectively for 1–3. The DNA-binding activity, explored via spectrophotometry and cyclic voltammetry, yielded intrinsic binding constant values of the order of 104 M−1 for all the complexes, showing excellent binding potency with DNA. The structural as well as biological importance of the complexes has been manifested.

Room Temperature Direct Electron Beam Lithography in a Condensed Copper Carboxylate.

High-resolution metallic nanostructures can be fabricated with multistep processes, such as electron beam lithography or ice lithography. The gas-assisted direct-write technique known as focused electron beam induced deposition (FEBID) is more versatile than the other candidates. However, it suffers from low throughput. This work presents the combined approach of FEBID and the above-mentioned lithography techniques: direct electron beam lithography (D-EBL). A low-volatility copper precursor is locally condensed onto a room temperature substrate and acts as a positive tone resist. A focused electron beam then directly irradiates the desired patterns, leading to local molecule dissociation. By rinsing or sublimation, the non-irradiated precursor is removed, leaving copper-containing structures. Deposits were formed with drastically enhanced growth rates than FEBID, and their composition was found to be comparable to gas-assisted FEBID structures. The influence of electron scattering within the substrate as well as implementing a post-purification protocol were studied. The latter led to the agglomeration of high-purity copper crystals. We present this as a new approach to electron beam-induced fabrication of metallic nanostructures without the need for cryogenic or hot substrates. D-EBL promises fast and easy fabrication results.

Two new copper (II) carboxylate complexes based on N,N,N',N'-tetramethylethyleneamine: Synthesis, crystal structures, spectral properties, dft studies and hirshfeld surface analysis

In this study, two new copper (II) carboxylate complexes, [Cu(4-mba)2(tmeda)](1) and [Cu(3-mba)2(H2O)2(tmeda)](2) (4-mbaH = 4-methylbenzoic acid, 3-mbaH = 3-methylbenzoic acid, tmeda = N,N,N',N'-tetramethylethyleneamine) were synthesized. The structures and properties of the complexes were determined by X-ray single crystal diffraction method and FT-IR spectroscopy. While the crystal packing of the complex 1 is stabilized by C—H•••O hydrogen bonds, in the complex 2, the molecules are connected to each other by C—H•••O and O—H•••O hydrogen bonds. The optimized structures were formed using density functional theory (DFT) at the B3LYP level within the 6–311G(d,p) and LAN2DZ basis sets. Their Hirshfeld surface analyses were performed for the detailed investigation of all the contacts involved in the crystal packing. 2D fingerprint plots and Hirshfeld surface analyses signify important interactions in the crystal packing [H⋯H (64.2%), C⋯H/H⋯C (21.1%) and O⋯H/H⋯O (14.7%) contacts for [Cu(4-mba)2(tmeda)], while [Cu(3-mba)2(H2O)2(tmeda)] showed H⋯H (67.3%), C⋯H/H⋯C (21.8%) and O⋯H/H⋯O (10.9%) contacts].

PAA Modified Upconversion Nanoparticles for Highly Selective and Sensitive Detection of Cu2+ Ions.

Detection of the Cu2+ ions is crucial because of its environmental and biological implications. The fluorescent-based organic sensors are not suitable for Cu2+ detection due to their short penetration depth caused by the UV/visible excitation source. Therefore, we have demonstrated a highly sensitive and selective near-infrared (NIR) excitable poly(acrylic acid) (PAA) coated upconversion nanoparticles (UCNPs) based sensor for Cu2+ detection. We construct the PAA modified Na(Yb, Nd)F4@Na(Yb, Gd)F4:Tm@NaGdF4 core-shell-shell structured UCNPs based sensor via a co-precipitation route. The upconversion emission intensity of the PAA-UCNPs decreases linearly with the increase in the Cu2+ concentration from 0.125 to 3.125 μM due to the copper carboxylate complex formation between Cu2+ and PAA-UCNPs. The calculated detection limit of the PAA-UCNPs based sensor is 0.1 μM. The PAA-UCNPs based sensor is very sensitive and selective toward detecting the Cu2+ ions, even when the Cu2+ co-exist with other metal ions. The EDTA addition has significantly reversed the upconversion emission quenching by forming the EDTA-Cu2+ complex based on their greater affinity toward the Cu2+. Therefore, the PAA-UCNPs based sensor can be a promising candidate for Cu2+ detection because of their higher sensitivity and selectivity under 980 nm NIR excitation.

Ring opening polymerization of d,l-lactide and ε-caprolactone catalysed by (pyrazol-1-yl)copper(ii) carboxylate complexes.

1,2-Bis{(3,5-dimethylpyrazol-1-yl)methyl}benzene (L) reacts with [Cu(OAc)2] and C6H5COOH, 4-OH-C6H4COOH, 2-Cl-C6H4COOH and (3,5-NO2)2-C6H3COOH to afford the copper complexes [Cu2(C6H5COO)4(L)2] (1), [Cu2(4-OH-C6H4COO)4(L)2] (2), [Cu2(2-Cl-C6H4COO)4(L)2]n (3) and [Cu{(3,5-NO2)2-C6H3COO}2L]n (4) which are characterised by IR, mass spectrometry, elemental analyses, and X-ray crystallography. The structural data revealed two geometries that are adopted by the complexes: (i) paddle wheel in 1, 2·7H2O, 3 and (ii) regular chains in 3 and 4. Magnetic studies show strong antiferromagnetic couplings in the paddle wheel complexes and a weak antiferromagnetic coupling in the monometallic chain one. Catalysis studies performed with these complexes (1–4) showed that they initiate ring opening polymerization (ROP) of ε-caprolactone (ε-CL) under solvent-free conditions and d,l-lactide in toluene at elevated temperatures. Polycaprolactone (PCL) and poly(d,l-lactide) (PLA) obtained from the polymerization reactions are of low molecular weights (858 for PCL and 602 Da for PLA for initiator 1) and polydispersity indices (typically 2.16 for PCL and 1.64 for PLA with 1 as the initiator). End group analysis of the polymers, determined by MALDI-ToF MS, indicates that the polymers have benzoate, hydroxyl, methoxy and cyclic end groups.

Synthesis, characterization, DNA binding ability, in vitro cytotoxicity, electrochemical properties and theoretical studies of copper(II) carboxylate complexes

Four copper(II) carboxylate complexes, namely [Cu2(μ-3,5-dinitrobenzoate-O,O')4(4-(dimethylamino)benzaldehyde)2] (1), [Cu2(μ-benzoate-O,O')4(benzoic acid)2] (2), [Cu2(μ-benzoate-O,O')4(H2O)2] [Cu(benzoate-O,O')2(imz)2].2H2O (3) and [Cu(benzoate-O,O')2(2-Me-imz)2] (4) (imz = imidazole, 2-Me-imz = 2-methyl-imidazole), were synthesized and comprehensively characterized by elemental analysis, spectroscopic methods, single crystal X-ray diffraction, cyclic voltammetry (CV), topological analysis as well as theoretical studies. Single crystal X-ray diffraction revealed that products 1 and 2 are dinuclear paddle-wheel complexes, compound 3 is a co-crystal containing mononuclear and dinuclear blocks, while compound 4 is a mononuclear complex. Hirshfeld surface analysis of the compounds rationalized different types of hydrogen bonds, which also lead to the generation of H-bonded networks in 3 and 4. Their topological analysis disclosed a uninodal 4-connected 2D layer with sql topology in 3 and a uninodal 2-connected 1D chain with 2C1 topology in 4. The interaction of 1–4 with calf thymus DNA was investigated by UV–visible and fluorescence spectroscopy, revealing a moderately strong non-intercalative mode of interaction. In vitro cytotoxicity study of the complexes on HepG2 (human liver hepatocellular carcinoma) cell lines revealed a significant inhibition activity. Electrochemical study of the complexes in CH3CN (1–3) and DMSO (4) solution showed a one electron transfer corresponding to Cu(III)Cu(II)/Cu(II)Cu(II) and Cu(II)Cu(II)/Cu(I)Cu(II) redox couples. The ΔE and Ipa/Ipc values suggest that the redox couples are quasireversible. The DFT study was performed to further rationalize the crystal structures and nuclearity of the obtained copper(II) complexes.

Structure of tetra-kis-(μ-deca-noato-κ2 O:O')bis-[(4-methyl-pyridine-κN)copper(II)], a dimeric copper(II) complex.

The 4-methyl-pyridine (4-Mepy) based dimeric copper(II) carboxyl-ate complex [Cu2(C10H19O2)4(C6H7N)2] or [Cu2(μ-O2CC9H19)4(4-Mepy)2] crystallizes with triclinic (P ) symmetry. The two CuII ions exhibit a distorted square-pyramidal environment and are connected into a centrosymmetric paddle-wheel dinuclear cluster [Cu⋯Cu = 2.6472 (8) Å] via four bridging carboxyl-ate ligands arranged in the syn-syn coordination mode. The apical positions around the paddle-wheel copper centers are occupied by the N atoms of the 4-methyl-pyridine ligands. The structure exhibits disorder of the terminal alkyl carbon atoms in the deca-noate chains.

Octahedral Copper(II) Carboxylates with 1,10-Phenanthroline: Synthesis, Structural Characterization, DNA-Binding and Anti-Fungal Properties

Two mono-nuclear axially distorted octahedral copper(II) complexes have been prepared and characterized via FT-IR, UV–Visible, elctrochemical, electron spin resonance and powder and single crystal XRD techniques. The complexes consist of a phenanthroline and two carboxylate ligands each bonded in bidentate fashion. Carboxylates are ortho-nitro-2-phenyl acetate (L1) and para-chloro-2-phenyl acetate (L2). Structural study showed that both complexes possess Jahn–Teller distorted octahedral geometry. The bulk purity was assessed from the matching experimental and simulated powder XRD spectra. The results of spectroscopic techniques are consistent with each other. ESR data revealed single electron occupancy of dx2 − y2 orbital with 2B1g as ground state typical of tetragonally distorted octahedral geometry. Electrochemical solution study showed diffusion controlled electron transfer processes with diffusion co-efficient values of 10.323 × 10–8 cm2s–1 and 0.972 × 10–8 cm2s–1 for 1 and 2. Complexes exhibited excellent DNA-binding activity studied via UV–Visible spectroscopy, cyclic voltammetry, florescence spectroscopy and viscometry yielding Kb values of 1.871 × 104 M–1 (1) and 1.577 × 104 M–1 (2), 0.38 × 104 M–1 (1) and 6.39 × 104 M–1 (2) and 2.1 × 106 M–1 (1) and 2.0 × 06 M–1 (2), respectively, for the first three techniques. Complexes possess good antifungal activity against three fungal strains.

Theoretical Characterization of Catalytically Active Species in Reductive Hydroxymethylation of Styrene with CO2 over a Bisphosphine-Ligated Copper Complex.

In this work, a density functional theory (DFT) study was performed to identify the catalytically active species in the copper-catalyzed three-component reductive hydroxymethylation of styrene with CO2 and hydrosilane. The calculations reveal that the dimeric copper(I) hydride species, formed in a mixture of the bisphosphine ligand, Cu(OAc)2, and hydrosilane, probably acts as the catalyst precursor. In the beginning, this species is catalytically competent to trigger the hydrocupration of styrene, along with the formation of the dimeric copper(I) alkyl intermediate. Subsequently, CO2 insertion into the dimeric copper(I) alkyl intermediate occurs, which is accompanied by the cleavage of the Cu-Cu bond and the generation of the monomeric copper(I) carboxylate intermediate. In the end, the sequential reduction of the monomeric copper(I) carboxylate intermediate with the hydrosilane produces the monomeric copper(I) hydride species as the actual catalyst and turns on the catalytic cycle. On the other hand, the monomeric copper(II) hydride species, yielded as the kinetic product in the initial reaction of the bisphosphine ligand, Cu(OAc)2, and hydrosilane, is also reactive for the hydrocupration of styrene. However, the resulting monomeric copper(II) alkyl intermediate is found to be the catalyst resting state, because of the much higher energy barrier demanded for the subsequent nucleophilic attack toward CO2. On the basis of the results of an activation-strain model (ASM) analysis and charge decomposition analysis (CDA), the low activity of the monomeric copper(II) alkyl intermediate can be ascribed to the more crowded environment around the central copper(II) ion and the weaker nucleophilicity of the alkyl moiety. Furthermore, all of the possible CuH species generated in the system are competent to promote the two-component hydrosilylation of CO2 with hydrosilane, which is an inevitable side reaction along with the reductive hydroxymethylation of styrene with CO2 and hydrosilane.

High-Purity Copper Structures from a Perfluorinated Copper Carboxylate Using Focused Electron Beam Induced Deposition and Post-Purification

The electron-induced modification of volatile physisorbed metal–organic molecules is the key process in focused electron beam induced deposition (FEBID). In this work, the perfluorinated copper car...