Why Is the Spontaneous Deprotonation of [Cu(uracil)2]2+ Complexes Accompanied by Enolization of the System?

The reaction‐force formalism is applied to carry out a detailed analysis of the mechanisms behind the enolization processes undergone by the complexes formed on interaction of uracil dimers with Cu²⁺ ions after spontaneous deprotonation of the resulting complexes. These enolization processes apparently involve a single proton transfer (PT) from an NH group to a carbonyl group of the same uracil moiety, which should involve a rather high activation barrier that prevents the process occurring. However, the reaction‐force, chemical‐potential, and electronic‐flux profiles unambiguously indicate that the actual mechanism involves three low‐barrier elementary steps, and this explains why enolization of the [Cu(uracil?H)(uracil)]⁺ complexes is a highly facile, assisted PT process. All of the observed PT processes show a typical profile for both the chemical potential and the electronic flux associated with the bond‐breaking and the bond‐formation processes.     

Cuprous Oxide Catalyzed Oxidative CC Bond Cleavage for CN Bond Formation: Synthesis of Cyclic Imides from Ketones and Amines

Selective oxidative cleavage of a C? C bond offers a straightforward method to functionalize organic skeletons. Reported herein is the oxidative C? C bond cleavage of ketone for C? N bond formation over a cuprous oxide catalyst with molecular oxygen as the oxidant. A wide range of ketones and amines are converted into cyclic imides with moderate to excellent yields. In‐depth studies show that both α‐C? H and β‐C? H bonds adjacent to the carbonyl groups are indispensable for the C? C bond cleavage. DFT calculations indicate the reaction is initiated with the oxidation of the α‐C? H bond. Amines lower the activation energy of the C? C bond cleavage, and thus promote the reaction. New insight into the C? C bond cleavage mechanism is presented.     

UV Emission of Gd3+ in the Presence of Cu2+: Towards Luminescence Quenching through Quantum Cutting?

The first investigation into the ultraviolet (UV) photoluminescence of gadolinium(III) in the presence of copper(II) is reported. A melt‐quenched barium phosphate glass was used as a model matrix. The optical spectroscopy assessment shows that with increasing CuO concentration the Cu²⁺ absorption band grows steadily, whereas the UV emission from Gd³⁺ ions is progressively quenched. The data, thus, suggests the existence of a Gd³⁺→Cu²⁺ energy‐transfer process ocurring through quantum cutting. A downconversion/cross‐relaxation pathway proceeding through a virtual state in Gd³⁺ is proposed. These findings suggest gadolinium(III) could potentially be used in the optical sensing of copper(II).     

Surface‐Enhanced Raman Scattering Based on Controllable‐Layer Graphene Shells Directly Synthesized on Cu Nanoparticles for Molecular Detection

Graphene shells with a controllable number of layers were directly synthesized on Cu nanoparticles (CuNPs) by chemical vapor deposition (CVD) to fabricate a graphene‐encapsulated CuNPs (G/CuNPs) hybrid system for surface‐enhanced Raman scattering (SERS). The enhanced Raman spectra of adenosine and rhodamine 6G (R6G) showed that the G/CuNPs hybrid system can strongly suppress background fluorescence and increase signal‐to‐noise ratio. In four different types of SERS systems, the G/CuNPs hybrid system exhibits more efficient SERS than a transferred graphene/CuNPs hybrid system and pure CuNPs and graphene substrates. The minimum detectable concentrations of adenosine and R6G by the G/CuNPs hybrid system can be as low as 10^?8 and 10^?10 M , respectively. The excellent linear relationship between Raman intensity and analyte concentration can be used for molecular detection. The graphene shell can also effectively prevent surface oxidation of Cu nanoparticles after exposure to ambient air and thus endow the hybrid system with a long lifetime. This work provides a basis for the fabrication of novel SERS substrates.     

Nanostructured copper‐coated solid‐phase microextraction fiber for gas chromatographic analysis of dibutyl phthalate and diethylhexyl phthalate environmental estrogens

A novel nanostructured copper‐based solid‐phase microextraction fiber was developed and applied for determining the two most common types of phthalate environmental estrogens (dibutyl phthalate and diethylhexyl phthalate) in aqueous samples, coupled to gas chromatography with flame ionization detection. The copper film was coated onto a stainless‐steel wire via an electroless plating process, which involved a surface activation process to improve the surface properties of the fiber. Several parameters affecting extraction efficiency such as extraction time, extraction temperature, ionic strength, desorption temperature, and desorption time were optimized by a factor‐by‐factor procedure to obtain the highest extraction efficiency. The as‐established method showed wide linear ranges (0.05–250 μg/L). Precision of single fiber repeatability was <7.0%, and fiber‐to‐fiber repeatability was <10%. Limits of detection were 0.01 μg/L. The proposed method exhibited better or comparable extraction performance compared with commercial and other lab‐made fibers, and excellent thermal stability and durability. The proposed method was applied successfully for the determination of model analytes in plastic soaking water.     

A Synthetic Route to Chiral Dihydrobenzothiazines through Ring Opening of Activated Aziridines with 2‐Halothiophenols/Copper‐Powder‐Mediated C−N Cyclization

A simple protocol for the synthesis of dihydrobenzothiazines through regio‐ and stereoselective S_N2‐type ring opening of N‐tosylaziridines with sulfur nucleophiles followed by copper‐powder‐mediated intramolecular C?N cyclization in excellent yields (up to 95 %) with high diastereo‐ and enantioselectivity (up to >99 %) is reported.     

Core–Shell Carbon‐Coated CuO Nanocomposites: A Highly Stable Electrode Material for Supercapacitors and Lithium‐Ion Batteries

Herein we present a simple method for fabricating core–shell mesostructured CuO@C nanocomposites by utilizing humic acid (HA) as a biomass carbon source. The electrochemical performances of CuO@C nanocomposites were evaluated as an electrode material for supercapacitors and lithium‐ion batteries. CuO@C exhibits an excellent capacitance of 207.2 F g^?1 at a current density of 1 A g^?1 within a potential window of 0–0.46 V in 6 M KOH solution. Significantly, CuO electrode materials achieve remarkable capacitance retentions of approximately 205.8 F g^?1 after 1000 cycles of charge/discharge testing. The CuO@C was further applied as an anode material for lithium‐ion batteries, and a high initial capacity of 1143.7 mA h g^?1 was achieved at a current density of 0.1 C. This work provides a facile and general approach to synthesize carbon‐based materials for application in large‐scale energy‐storage systems.     

电感耦合等离子体原子发射光谱法(ICP-AES)测定铜渣精矿中杂质含量

采用电感耦合等离子体发射光谱法测定了铜渣精矿中砷、锑、铋、铅、锌、镁的量。其测定范围:ω(As):0.05%~0.45%,ω(Sb):0.07%~0.30%,ω(Bi):0.01%~0.20%,ω(Pb):1.00%~4.50%,ω(Zn):1.00%~4.50%,ω(Mg):0.10%~1.00%。经加标回收实验,各元素的加标回收率为92%~104%(n=3),相对标准偏差(RSD)小于5%(n=11)。方法准确快速可靠,适用于铜渣精矿中砷、锑、铋、铅、锌、镁量的同时测定.     

One‐dimensional CuII coordination polymers containing C2h‐symmetric 1,1′:4′,1′′‐terphenyl‐3,3′‐dicarboxylate linkers

Two new one‐dimensional Cu^II coordination polymers (CPs) containing the C_2h‐symmetric terphenyl‐based dicarboxylate linker 1,1′:4′,1′′‐terphenyl‐3,3′‐dicarboxylate (3,3′‐TPDC), namely catena‐poly[[bis(dimethylamine‐κN)copper(II)]‐μ‐1,1′:4′,1′′‐terphenyl‐3,3′‐dicarboxylato‐κ⁴O,O′:O′′:O′′′] monohydrate], {[Cu(C₂₀H₁₂O₄)(C₂H₇N)₂]·H₂O}_n, (I), and catena‐poly[[aquabis(dimethylamine‐κN)copper(II)]‐μ‐1,1′:4′,1′′‐terphenyl‐3,3′‐dicarboxylato‐κ²O³:O^3′] monohydrate], {[Cu(C₂₀H₁₂O₄)(C₂H₇N)₂(H₂O)]·H₂O}_n, (II), were both obtained from two different methods of preparation: one reaction was performed in the presence of 1,4‐diazabicyclo[2.2.2]octane (DABCO) as a potential pillar ligand and the other was carried out in the absence of the DABCO pillar. Both reactions afforded crystals of different colours, i.e. violet plates for (I) and blue needles for (II), both of which were analysed by X‐ray crystallography. The 3,3′‐TPDC bridging ligands coordinate the Cu^II ions in asymmetric chelating modes in (I) and in monodenate binding modes in (II), forming one‐dimensional chains in each case. Both coordination polymers contain two coordinated dimethylamine ligands in mutually trans positions, and there is an additional aqua ligand in (II). The solvent water molecules are involved in hydrogen bonds between the one‐dimensional coordination polymer chains, forming a two‐dimensional network in (I) and a three‐dimensional network in (II).