Over the past few years, CuH‐catalyzed hydroamination has been discovered and developed as a robust and conceptually novel approach for the synthesis of enantioenriched secondary and tertiary amines. ...The success in this area of research was made possible through the large body of precedent in copper(I) hydride catalysis and the well‐explored use of hydroxylamine esters as electrophilic amine sources in related copper‐catalyzed processes. This Minireview details the background, advances, and mechanistic investigations in CuH‐catalyzed hydroamination.
Mild and abundant: CuH‐catalyzed hydroamination has recently been developed as a viable method for synthesizing a broad range of chiral aliphatic amines in excellent efficiencies and enantioselectivites. This Minireview highlights advancements made in this area of catalysis along with the precedent that has led to these discoveries.
The introduction of a trifluoromethyl (CF
) group can dramatically improve a compound's biological properties. Despite the well-established importance of trifluoromethylated compounds, general ...methods for the trifluoromethylation of alkyl C-H bonds remain elusive. Here we report the development of a dual-catalytic C(sp
)-H trifluoromethylation through the merger of light-driven, decatungstate-catalysed hydrogen atom transfer and copper catalysis. This metallaphotoredox methodology enables the direct conversion of both strong aliphatic and benzylic C-H bonds into the corresponding C(sp
)-CF
products in a single step using a bench-stable, commercially available trifluoromethylation reagent. The reaction requires only a single equivalent of substrate and proceeds with excellent selectivity for positions distal to unprotected amines. To demonstrate the utility of this new methodology for late-stage functionalization, we have directly derivatized a broad range of approved drugs and natural products to generate valuable trifluoromethylated analogues. Preliminary mechanistic experiments reveal that a 'Cu-CF
' species is formed during this process and the critical C(sp
)-CF
bond-forming step involves the copper catalyst.
In this study, two endophytic actinomycetes isolates Oc-5 and Acv-11, were isolated from healthy leaves of medicinal plant
Oxalis corniculata L
. These isolates were identified as
Streptomyces ...zaomyceticus
Oc-5 and
Streptomyces pseudogriseolus
Acv-11 using 16S rRNA gene sequence. Biomass extract of these strains were used as a greener attempt for synthesis of copper oxide nanoparticles (CuO-NPs). The synthesized NPs were characterized by UV–Vis spectroscopy, Fourier transform infra-red (FT-IR) spectroscopy, X-ray diffraction (XRD)‚ transmission electron microscopy (TEM), energy dispersive X-ray (EDX) and X-ray photoelectron spectroscopy (XPS). Green synthesized NPs showed surface plasmon resonance (SPR) absorption band at 400 nm, crystalline nature, spherical-shaped with an average size of 78 nm and 80.0 nm for CuO-NPs synthesized using strain Oc-5 and Acv-11, respectively. The bioactivities of CuO-NPs were evaluated. Results revealed that CuO-NPs exhibited promising antimicrobial activity against prokaryotic and eukaryotic microbial cells (Gram positive bacteria, Gram negative bacteria, unicellular and multicellular fungi). In addition, it showed antimicrobial potential against phyto-pathogenic fungal strains
Fusarium oxysporum, Pythium ultimum, Aspergillus niger
and
Alternaria alternata.
We further explored the in vitro antioxidant activity and cytotoxicity for biosynthesized CuO-NPs. The results revealed that‚ scavenging and total antioxidant activity for NPs synthesized using
Streptomyces pseudogriseolus
Acv-11 was better than those synthesized by
Streptomyces zaomyceticus
Oc-5. Also, the morphological changes and cell viability for Vero and Caco-2 cell line due to NPs treatments were assessed using MTT assay method. Furthermore, Larvicidal efficacy against
Musca domestica
and
Culex pipiens
was evaluated. The results obtained in this study clearly showed that biosynthesized CuO-NPs exhibited effective bioactivity and, therefore, provide a base for the development of versatile biotechnological applications soon.
The electroreduction of carbon dioxide (CO2RR) to CH4 stands as one of the promising paths for resourceful CO2 utilization in meeting the imminent “carbon‐neutral” goal of the near future. Yet, ...limited success has been witnessed in the development of high‐efficiency catalysts imparting satisfactory methane selectivity at a commercially viable current density. Herein, a unique category of CO2RR catalysts is fabricated with the yolk–shell nanocell structure, comprising an Ag core and a Cu2O shell that resembles the tandem nanoreactor. By fixing the Ag core and tuning the Cu2O envelope size, the CO flux arriving at the oxide‐derived Cu shell can be regulated, which further modulates the *CO coverage and *H adsorption at the Cu surface, consequently steering the CO2RR pathway. Density functional theory simulations show that lower CO coverage favors methane formation via stabilizing the intermediate *CHO. As a result, the best catalyst in the flow cell shows a high CH4 Faraday efficiency of 74 ± 2% and partial current density of 178 ± 5 mA cm−2 at −1.2 VRHE, ranking above the state‐of‐the‐art catalysts reported today for methane production. These findings mark the significance of precision synthesis in tailoring the catalyst geometry for achieving desired CO2RR performance.
A unique category of CO2RR catalysts with a yolk–shell nanocell structure, comprising an Ag core and a Cu2O shell that resembles a tandem nanoreactor, is fabricated. The shell envelope size can be finely tuned to regulate the CO flux arriving at the oxide‐derived Cu shell, which further modulates *CO coverage and *H adsorption, consequently steering the electrocatalytic CO2RR pathway.
Cu-In-Ga precursor thin films were deposited onto soda lime glass by magnetron cosputtering CuIn and CuGa alloy targets. After that, Cu(In,Ga)Se2(CIGSe) absorbers were formed by selenizing those ...alloy precursors with Se vapor at 550 degree C. The influence of the precursor temperature on the properties of CIGSe thin film was investigated. The results show that a lot of pinholes existed in the CIGSe thin film produced by selenizing the Cu-In-Ga alloy precursor, which was sputtering deposited at ambient temperature. After sputtering substrate temperature of 250 degree C was applied, pinholes were avoided. The surface roughness of Cu-In-Ga precursor increased with the increase of sputtering substrate temperature. Due to the volume expansion of selenization process, even the precursor with high surface roughness could be converted to smooth and compact CIGSe thin film.
Cu6Sn5 is a critical intermetallic compound in soldering operations. Conventional equilibrium phase diagrams show that this compound is of either a hexagonal or monoclinic structure at temperatures ...above and below 186 degree C, respectively. Under nonequilibrium conditions, the crystal structure is dependent on composition, temperature, and processing history. The effect of Zn, Au, and In on the hexagonal to monoclinic polymorphic transformation in Cu6Sn5 intermetallics is investigated using variable temperature synchrotron powder x-ray diffraction and differential scanning calorimetry. It is revealed that, as in the case of trace Ni additions, the alloying elements Zn and Au completely stabilize the hexagonal Cu6Sn5 and prevent the phase transformation. In contrast, In additions only partially stabilize the hexagonal Cu6Sn5.
Herein, we report the copper-catalyzed dehydrogenative C(spsup.2)–N bond formation of 4-pentenamides via nitrogen-centered radicals. This reaction provides a straightforward and efficient preparation ...method for γ-alkylidene-γ-lactams. Notably, we could controllably synthesize α,β-unsaturated- or α,β-saturated-γ-alkylidene-γ-lactams depending on the reaction conditions.
Copper is an essential cofactor for all organisms, and yet it becomes toxic if concentrations exceed a threshold maintained by evolutionarily conserved homeostatic mechanisms. How excess copper ...induces cell death, however, is unknown. Here, we show in human cells that copper-dependent, regulated cell death is distinct from known death mechanisms and is dependent on mitochondrial respiration. We show that copper-dependent death occurs by means of direct binding of copper to lipoylated components of the tricarboxylic acid (TCA) cycle. This results in lipoylated protein aggregation and subsequent iron-sulfur cluster protein loss, which leads to proteotoxic stress and ultimately cell death. These findings may explain the need for ancient copper homeostatic mechanisms.
Copper is crucial for carrying out normal physiological functions in all higher life forms. Copper Transporter 1 (CTR1) is the high-affinity copper importer found in all eukaryotic organisms. The ...copper transporter family primarily comprises ~ six members (CTR1-6) and the related members share high sequence homology with CTR. However, with the exception of CTR1, not all six CTRs are present in every organism. Despite having a simple trimeric channel structure, CTR1 and other members exhibit some unique regulatory properties. In the present review, we attempt to understand the diversity and similarity of regulation and functioning of the members of this copper transporter family.
Graphic Abstract
Copper (Cu) is an essential micronutrient but excess Cu is potentially toxic. Its important propensity to cycle between two oxidation states accounts for its frequent presence as a cofactor in many ...physiological processes through Cu-containing enzymes, including mitochondrial energy production (via cytochrome c-oxidase), protection against oxidative stress (via superoxide dismutase), and extracellular matrix stability (via lysyl oxidase). Since free Cu is potentially toxic, the bioavailability of intracellular Cu is tightly controlled by Cu transporters and Cu chaperones. Recent evidence reveals that these Cu transport systems play an essential role in the physiological responses of cardiovascular cells, including cell growth, migration, angiogenesis and wound repair. In response to growth factors, cytokines, and hypoxia, their expression, subcellular localization, and function are tightly regulated. Cu transport systems and their regulators have also been linked to various cardiovascular pathophysiologies such as hypertension, inflammation, atherosclerosis, diabetes, cardiac hypertrophy, and cardiomyopathy. A greater appreciation of the central importance of Cu transporters and Cu chaperones in cell signaling and gene expression in cardiovascular biology offers the possibility of identifying new therapeutic targets for cardiovascular disease.
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