XANES/EPR Evidence of the Oxidation of Nickel(II) Quinolinylpropioamide and Its Application in Csp3−H Functionalization

An in situ generated oxidation species of nickel quinolinylpropioamide intermediate was produced. Characterization by X-ray absorption near edge structure (XANES) and EPR provides complementary insights into this oxidized nickel species. With aliphatic amides and isocyanides as substrates, a nickel-catalyzed facile synthesis of structurally diverse five-membered lactams could be achieved.     

Instabilities of soap film structures in square cuboid frame

ABSTRACT

Through the simulations performed with the Surface Evolver, we explored the T1s and the eight-fold vertex related topological changes in the square cuboid frame by changing the axial ratio λ and the liquid fraction ?. A stability diagram is provided to illustrate the instabilities encountered in any quasi-static process. Metastable film configurations are always accompanied by pre-emptive instabilities, while the instabilities of stable film configurations are not triggered until the central quadrilateral film steadily vanishes.     

Interim Anatase Coating Layer Stabilizes Rutile@CrxOy Photoanode for Visible‐Light‐Driven Water Oxidation

Ternary core–shell heterostructured rutile@anatase@Cr_xO_y nanorod arrays were elaborately designed as photoanodes for efficient photoelectrochemical water splitting under visible‐light illumination. The four‐fold enhanced and stabilized visible‐light photocurrent highlights the unique role of the interim anatase layer in accelerating the interfacial charge transfer from the Cr_xO_y chromophore to rutile nanorods.     

Monodispersed AuPd nanoalloy: composition control synthesis and catalytic properties in the oxidative dehydrogenative coupling of aniline

A series of AuPd@C nanoalloy catalysts with tunable compositions were successfully prepared by a co-reduction method. The use of borane-tert-butylamine complex as reductant and oleylamine as both solvent and reductant was very effective for the preparation of the monodispersed nanoalloy. We evaluated the catalytic activity of these AuPd@C nanoalloys for oxidative dehydrogenative coupling of aniline, which showed better catalytic activity than equal amounts of sole Au@C or Pd@C catalyst. The Au₁Pd₃@C catalyst exhibited the best performance, indicating that the conversion and selectivity were improved along with the increase of Pd composition. However if the Pd composition was too high in the AuPd alloy, Au₁Pd₇@C achieved only 81% conversion in this reaction.     

Highly Efficient Circularly Polarized Luminescence from Chiral Au13 Clusters Stabilized by Enantiopure Monodentate NHC Ligands

Chiral Au nanoclusters have promising application prospects in chiral sensing, asymmetric catalysis, and chiroptics. However, enantiopure superatomic homogold clusters with crystallographic structures emitting bright circularly polarized luminescence (CPL) remain challenging. In this study, we designed chiral N-heterocyclic carbenes (NHCs), and for the first time enantioselectively synthesized a pair of monovalent cationic superatomic Au₁₃ clusters. This new enantiomeric pair of clusters has a quasi-C₂ symmetric core and exhibited CPL with an unprecedent solution-state quantum yield (QY) of 61 % among those of the atomically precise Au nanoclusters. DFT calculations provided insights into the circular dichroism behavior, and revealed the origin of CPL from superatomic Au clusters. This work opens a new avenue for developing novel homochiral nanoclusters using chiral NHC ligands and provides fundamental understanding of the origin of the chiroptics of metal clusters.     

Boron-Cluster Embedded Necklace-Shaped Nanohoops

The combination of carbon-based nanohoops with other functional organic molecular structures should lead to the design of new molecular configurations with interesting properties. Here, necklace-like nanohoops embedded with carborane were synthesized for the first time. The unique deboronization of o-carborane has led to the facile preparation of ionic nanohoop compounds. Nanohoops functionalized by nido-o-carborane show excellent fluorescence emission, with a solution quantum yield of up to 90.0 % in THF and a solid-state quantum efficiency of 87.3 %, which opens an avenue for the applications of the nanohoops in OLEDs and bioimaging.     

锂离子电池硅氧化物负极首次库伦效率的影响因素与提升策略

硅氧化物(SiO_x, 0<x≤2)具有高的比容量和低的嵌锂电位, 且体积膨胀率显著低于纯硅负极, 因而被认为是替代传统石墨负极材料的理想选择之一. 然而SiO_x负极在首次嵌锂过程中表面形成的固体电解质界面膜(SEI)以及大量的不可逆产物, 造成其首次库伦效率偏低, 严重阻碍了SiO_x负极的实际应用. 本文从SiO_x的结构模型出发, 系统阐述了SiO_x负极的嵌锂机理以及首次库伦效率低的原因; 归纳了SiO_x负极首次库伦效率的提升策略及其研究进展; 并对提升SiO_x负极首次库伦效率的未来发展方向进行了展望.     

Cu Doping-Induced Transformation from [Ag62S12(SBut)32]2+ to [Ag62−xCuxS12(SBut)32]4+ Nanocluster

The change in the valence state of nanocluster can induce remarkable changes in the properties and structure. However, achieving the valence state changes in nanoclusters is still a challenge. In this work, we use Cu²⁺ as dopant to “oxidize” [Ag₆₂S₁₂(SBu^t)₃₂]²⁺ (4 free electrons) to obtain the new nanocluster: [Ag_62−xCu_xS₁₂(SBu^t)₃₂]⁴⁺ with 2 free electrons. As revealed by its structure, the [Ag_62−xCu_xS₁₂(SBu^t)₃₂]⁴⁺ (x=10∼21) has a similar structure to that of [Ag₆₂S₁₂(SBu^t)₃₂]²⁺ precursor and all the Cu atoms occupy the surface site of nanocluster. It′s worth noting that with the Cu atoms doping, the [Ag_62−xCu_xS₁₂(SBu^t)₃₂]⁴⁺ nanocluster is more stable than [Ag₆₂S₁₂(SBu^t)₃₂]²⁺ at higher temperature and in electrochemical cycle. This result has laid a foundation for the subsequent application and exploration. Overall, this work reveals crystals structure of a new Ag−Cu nanocluster and offers a new insight into the electron reduction/oxidation of nanocluster.     

Three New Phenyl Ether Derivatives from Aspergillus carneus HQ889708

Three new phenyl ether derivatives, 3‐hydroxy‐5‐(3‐hydroxy‐5‐methylphenoxy)benzoic acid ( 1 ), 3,4‐dihydroxy‐5‐(3‐hydroxy‐5‐methylphenoxy)benzoic acid ( 2 ), 3‐[3‐hydroxy‐5‐(hydroxymethyl)phenoxy]‐5‐methylphenol ( 3 ), and three known compounds 4 – 6 were obtained from the fermentation broth of Aspergillus carneus HQ889708, which was isolated from sea water from South China Sea. The structures of compounds 1 – 3 were established on the basis of spectroscopic methods including ESI‐MS and NMR. Compounds 4 – 6 were reported before as synthesized products, herein, they are reported from nature for the first time.