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91.
Layered Black Phosphorus: Strongly Anisotropic Magnetic,Electronic, and Electron‐Transfer Properties
Zdenk Sofer David Sedmidubský tpn Huber Jan Luxa Daniel Boua Chris Boothroyd Martin Pumera 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2016,128(10):3443-3447
Layered elemental materials, such as black phosphorus, exhibit unique properties originating from their highly anisotropic layered structure. The results presented herein demonstrate an anomalous anisotropy for the electrical, magnetic, and electrochemical properties of black phosphorus. It is shown that heterogeneous electron transfer from black phosphorus to outer‐ and inner‐sphere molecular probes is highly anisotropic. The electron‐transfer rates differ at the basal and edge planes. These unusual properties were interpreted by means of calculations, manifesting the metallic character of the edge planes as compared to the semiconducting properties of the basal plane. This indicates that black phosphorus belongs to a group of materials known as topological insulators. Consequently, these effects render the magnetic properties highly anisotropic, as both diamagnetic and paramagnetic behavior can be observed depending on the orientation in the magnetic field. 相似文献
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93.
A Selective RhI‐Catalyzed Substrate‐Controlled C−C Bond Activation of Benzyl Sulfonamide/Alcohol‐Tethered Alkylidenecyclopropanes 下载免费PDF全文
Kai Chen Jia‐Xin Liu Dr. Xiang‐Ying Tang Prof. Min Shi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(33):11549-11553
Benzyl sulfonamide/alcohol‐tethered alkylidenecyclopropanes undergo a rhodium‐catalyzed and substrate‐controlled selective C?C bond activation, producing three types of common organic structural units: benzo[c]azepine/oxepines, dihydronaphthalen‐1‐amines, and conjugated dienes. Epoxidation and aromatization of these products to construct two useful compounds have also been achieved. 相似文献
94.
Catalytic Activity of Cationic and Neutral Silver(I)–XPhos Complexes with Nitrogen Ligands or Tolylsulfonate for Mannich and Aza‐Diels–Alder Coupling Reactions 下载免费PDF全文
Dr. Abdessamad Grirrane Dr. Eleuterio Álvarez Prof. Dr. Hermenegildo García Prof. Dr. Avelino Corma 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(1):340-354
Cationic and neutral silver(I)–L complexes (L=Buchwald‐type biaryl phosphanes) with nitrogen co‐ligands or organosulfonate counter ions have been synthesised and characterised through their structural and spectroscopic properties. At room temperature, both cationic and neutral silver(I)–L complexes are extremely active catalysts in the promotion of the single and double A3 coupling of terminal (di)alkynes, pyrrolidine and formaldehyde. In addition, the aza‐Diels–Alder two‐ and three‐component coupling reactions of Danishefsky’s diene with an imine or amine and aldehyde are efficiently catalysed by these cationic or neutral silver(I)–L complexes. The solvent influences the catalytic performance due to limited complex solubility or solvent decomposition and reactivity. The isolation of new silver(I)–L complexes with reagents as ligands lends support to mechanistic proposals for such catalytic processes. The activity, stability and metal–distal arene interaction of these silver(I)–L catalysts have been compared with those of analogous cationic gold(I) and copper(I) complexes. 相似文献
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98.
Non‐coordinating‐Anion‐Directed Reversal of Activation Site: Selective C−H Bond Activation of N‐Aryl Rings 下载免费PDF全文
Prof. Dr. Dawei Wang Xiaoli Yu Prof. Dr. Xiang Xu Bingyang Ge Xiaoli Wang Yaxuan Zhang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(25):8663-8668
An Rh‐catalyzed selective C?H bond activation of diaryl‐substituted anilides is described. In an attempt to achieve C?H activation of C‐aryl rings, we unexpectedly obtained an N‐aryl ring product under non‐coordinating anion conditions, whereas the C‐aryl ring product was obtained in the absence of a non‐coordinating anion. This methodology has proved to be an excellent means of tuning and adjusting selective C?H bond activation of C‐aryl and N‐aryl rings. The approach has been rationalized by mechanistic studies and theoretical calculations. In addition, it has been found and verified that the catalytic activity of the rhodium catalyst is obviously improved by non‐coordinating anions, which provides an efficient strategy for obtaining a highly chemoselective catalyst. Mechanistic experiments also unequivocally ruled out the possibility of a so‐called “silver effect” in this transformation involving silver. 相似文献
99.
Self‐Assembly and Compartmentalization of Nanozymes in Mesoporous Silica‐Based Nanoreactors 下载免费PDF全文
Yanyan Huang Dr. Youhui Lin Xiang Ran Prof. Dr. Jinsong Ren Prof. Dr. Xiaogang Qu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(16):5705-5711
Herein, to mimic complex natural system, polyelectrolyte multilayer (PEM)‐coated mesoporous silica nanoreactors were used to compartmentalize two different artificial enzymes. PEMs coated on the surface of mesoporous silica could serve as a permeable membrane to control the flow of molecules. When assembling hemin on the surface of mesoporous silica, the hemin‐based mesoporous silica system possessed remarkable peroxidase‐like activity, especially at physiological pH, and could be recycled more easily than traditional graphene–hemin nanocompounds. The hope is that these new findings may pave the way for exploring novel nanoreactors to achieve compartmentalization of nanozymes and applying artificial cascade catalytic systems to mimic cell organelles or important biochemical transformations 相似文献
100.
ABSTRACT The compressibility and effect of pressure on the vibrations of merrillite, Ca9NaMg(PO4)7, were studied by using diamond anvil cell at room temperature combined with in-situ synchrotron X-ray diffraction and Raman spectroscopy up to about 18 and 15?GPa, respectively. The pressure-volume data was fitted by a third-order Birch–Murnaghan equation of state to determine the isothermal bulk modulus as K0 ?=?87.2(32) GPa with pressure derivative K0′?=?3.2(4). If K0′?=?4, the isothermal bulk modulus was obtained as 81.6(10) GPa. The axial compressibility was estimated and an axial elastic anisotropy exists since a-axis is less compressible than the c-axis. The Raman frequencies of all observed modes for merrillite continuously increase with pressure, and the pressure dependences of stretching modes (v 3 and v 1) are larger than those of the bending modes (v 4 and v 2) and external modes. The isothermal mode Grüneisen parameters and intrinsic anharmonicity of merrillite were also calculated. 相似文献