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1.
Keith Izod Peter Evans Paul G. Waddell 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(32):11123-11128
Stable acyclic arsenium cations R2As+, isoelectronic analogues of germylenes, are rare in comparison to the corresponding phosphenium cations. The first example of a diphosphaarsenium salt, [{(Dipp)2P}2As][Al{OC(CF3)3}4]?1 PhMe, is described. This salt exhibits remarkable stability due to the delocalisation of a lone pair from a planar phosphorus centre into the vacant p‐orbital at arsenic; the bonding in 2 has been probed by DFT calculations. An attempt to synthesise an analogous diphosphaphosphenium salt unexpectedly generated the cyclic phosphonium salt [cyclo‐{(Mes)P}2P(Mes)2][BArF4]?CyMe through the cyclisation of a putative phosphine‐substituted diphosphene cation intermediate. 相似文献
2.
Yongfeng Tao Keighley Reisenauer Joseph H. Taube Daniel Romo 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(9):2760-2764
The hypercalins are dearomatized acylphloroglucinols with a pendant complex cyclopentane ring that exhibit activity against several cancer cell lines. We report the first total synthesis of (+)‐hypercalin C employing a convergent strategy that enabled the dissection of the essential structural features required for the observed anticancer activity. A strategic disconnection involving an unusual C –C Suzuki–Miyaura coupling with an α‐bromo enolether also revealed an unexpected C?H activation. This strategy targeted designed analogues along the synthetic route to address particular biological questions. These results support the hypothesis that hypercalin C may act as a proton shuttle with the dearomatized acylphloroglucinol moiety being essential for this activity. 相似文献
3.
Dr. Guoju Yang Dr. Sneha A. Akhade Xi Chen Dr. Yue Liu Dr. Mal‐Soon Lee Dr. Vassiliki‐Alexandra Glezakou Dr. Roger Rousseau Prof. Dr. Johannes A. Lercher 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(11):3565-3570
The thermodynamic state of H2 adsorbed on Pt in the aqueous phase was determined by kinetic analysis of H2 reacting with D2O to HDO, HD, and D2, and by DFT‐based ab initio molecular dynamics simulations of H2 adsorption on Pt(111), Pt(110), and Pt nanoparticles. Dissociative adsorption of H2 on Pt is significantly weakened in the aqueous phase compared to adsorption at gas–solid interfaces. Water destabilizes the adsorbed H atoms, decreasing the heat of adsorption by 19–22 kJ while inducing an additional entropy loss of 50–70 J K?1. Upon dissociative adsorption of H2, the average distance of water from the Pt surface increases and the liquid adopts a structure that is more ordered than before close to the Pt surface, which limits the translation mobility of the adsorbed H atoms. The presence of hydrated hydronium ions next to the Pt surface further lowers the H?Pt bond strength. 相似文献
4.
Daniel E. Diaz David A. Quist Austin E. Herzog Andrew W. Schaefer Ioannis Kipouros Mayukh Bhadra Edward I. Solomon Kenneth D. Karlin 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(49):17736-17740
The dioxygen reactivity of a series of TMPA‐based copper(I) complexes (TMPA=tris(2‐pyridylmethyl)amine), with and without secondary‐coordination‐sphere hydrogen‐bonding moieties, was studied at ?135 °C in 2‐methyltetrahydrofuran (MeTHF). Kinetic stabilization of the H‐bonded [( TMPA)CuII(O2.?)]+ cupric superoxide species was achieved, and they were characterized by resonance Raman (rR) spectroscopy. The structures and physical properties of [( TMPA)CuII(N3?)]+ azido analogues were compared, and the O2.? reactivity of ligand–CuI complexes when an H‐bonding moiety is replaced by a methyl group was contrasted. A drastic enhancement in the reactivity of the cupric superoxide towards phenolic substrates as well as oxidation of substrates possessing moderate C?H bond‐dissociation energies is observed, correlating with the number and strength of the H‐bonding groups. 相似文献
5.
Shinsaku Amano Dimitri Bogdanovski Hisanori Yamane Masami Terauchi Richard Dronskowski 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2016,128(5):1684-1689
For the Ti/O system, three titanium monoxide (TiO) phases (α, β, and γ) with defective NaCl‐type structures and a high‐temperature hexagonal phase (H) have been known for decades. In this work, single crystals of a novel polymorph, ɛ‐TiO, were synthesized by using a bismuth flux. X‐ray diffraction (XRD) revealed a hexagonal crystal structure (a=4.9936(3) Å, c=2.8773(2) Å, P 2m) that is isotypic with ɛ‐TaN. While the Ti atoms are surrounded by trigonal prismatic (sixfold coordination) and trigonal planar (threefold coordination) arrangements of O atoms, the O atoms are found in a pseudo‐square‐pyramidal arrangement of Ti atoms. First‐principles calculations of the formation enthalpy and the electron and phonon density of states and crystal orbital Hamilton population (COHP) analysis revealed that ɛ‐TiO is more stable than α‐TiO, which had previously been regarded as the most stable phase at low temperatures. 相似文献
6.
Gemeng Liang Zhibin Wu Dr. Christophe Didier Dr. Wenchao Zhang Dr. Jing Cuan Prof. Baohua Li Kuan-Yu Ko Po-Yang Hung Dr. Cheng-Zhang Lu Dr. Yuanzhen Chen Dr. Grzegorz Leniec Dr. Sławomir Maksymilian Kaczmarek Dr. Bernt Johannessen Dr. Lars Thomsen Dr. Vanessa K. Peterson Dr. Wei Kong Pang Prof. Zaiping Guo 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(26):10681-10689
Spinel LiNi0.5Mn1.5O4 (LNMO) is a promising cathode candidate for the next-generation high energy-density lithium-ion batteries (LIBs). Unfortunately, the application of LNMO is hindered by its poor cycle stability. Now, site-selectively doped LNMO electrode is prepared with exceptional durability. In this work, Mg is selectively doped onto both tetrahedral (8a) and octahedral (16c) sites in the Fd m structure. This site-selective doping not only suppresses unfavorable two-phase reactions and stabilizes the LNMO structure against structural deformation, but also mitigates the dissolution of Mn during cycling. Mg-doped LNMOs exhibit extraordinarily stable electrochemical performance in both half-cells and prototype full-batteries with novel TiNb2O7 counter-electrodes. This work pioneers an atomic-doping engineering strategy for electrode materials that could be extended to other energy materials to create high-performance devices. 相似文献
7.
Qingxin Chu Xiaofeng Wang Qiliang Li Xiaoyang Liu 《Acta Crystallographica. Section C, Structural Chemistry》2011,67(2):i10-i12
The title compound, tetrasodium nonamanganese octadecaoxide, Na4.32Mn9O18, was synthesized by reacting Mn2O3 with NaCl. One Mn atom occupies a site of 2/m symmetry, while all other atoms sit on mirror planes. The compound is isostructural with Na4Ti4Mn5O18 and suggestive of Mn3+/Mn4+ charge ordering. It has a double‐tunnel structure built up from double and triple chains of MnO6 octahedra and single chains of MnO5 square pyramids by corner sharing. Disordered Na+ cations occupy four crystallographic sites within the tunnels, including an unexpected new Na+ site discovered inside the large S‐shaped tunnel. A local‐ordering model is used to show the possible Na+ distribution, and the unit‐cell evolution during charging/discharging is explained on the basis of this local‐ordering model. 相似文献
8.
Kerstin Mayer Jasmin V. Dums Christian B. Benda Wilhelm Klein Thomas F. Fssler 《Angewandte Chemie (International ed. in English)》2020,59(17):6800-6805
Polymeric [Bi]? in KBi?NH3 has planar zigzag chains with two‐connected Bi atoms and metallic properties, whereas KBi, which has helical chains of Bi atoms, is semiconducting. The isomerization of the Bi chain is induced by solvate molecules. In the novel layered solvate structure uncharged [KBi] layers are separated by intercalated NH3 molecules. These layers are a structural excerpt of the iso(valence)electronic CaSi, whose metallic properties arise from the planarity of the zigzag chain of Si atoms. Computational studies support this view, they show an anisotropic metallic behavior along the Bi chain. Electron delocalization is also found in the new cyclic anion [Bi6]4? isolated in K2[K(18‐crown‐6)]2[Bi6]?9 NH3. Although [Bi6]4? should exhibit one localized double bond, electron delocalization is observed in analogy to the lighter homologues [P6]4? and [As6]4?. Both compounds were characterized by single‐crystal X‐ray structure determination. 相似文献
9.
Lili Han Xijun Liu Jinping Chen Ruoqian Lin Haoxuan Liu Fang Lü Seongmin Bak Zhixiu Liang Shunzheng Zhao Eli Stavitski Jun Luo Radoslav R. Adzic Huolin L. Xin 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(8):2343-2347
NH3 synthesis by the electrocatalytic N2 reduction reaction (NRR) under ambient conditions is an appealing alternative to the currently employed industrial method—the Haber–Bosch process—that requires high temperature and pressure. We report single Mo atoms anchored to nitrogen‐doped porous carbon as a cost‐effective catalyst for the NRR. Benefiting from the optimally high density of active sites and hierarchically porous carbon frameworks, this catalyst achieves a high NH3 yield rate (34.0±3.6 μg h?1 mgcat.?1) and a high Faradaic efficiency (14.6±1.6 %) in 0.1 m KOH at room temperature. These values are considerably higher compared to previously reported non‐precious‐metal electrocatalysts. Moreover, this catalyst displays no obvious current drop during a 50 000 s NRR, and high activity and durability are achieved in 0.1 m HCl. The findings provide a promising lead for the design of efficient and robust single‐atom non‐precious‐metal catalysts for the electrocatalytic NRR. 相似文献
10.
Li‐Fang Zhang Zhong‐Hai Ni Zhi‐Min Zong Xian‐Yong Wei Chun‐Hua Ge Hui‐Zhong Kou 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(12):m542-m544
In the title one‐dimensional complex, {[MnIII(C9H10NO2)2]Cl}n, the Schiff base ligand 2‐[(2‐hydroxyethyl)iminomethyl]phenolate (Hsae−) functions as both a bridging and a chelating ligand. The MnIII ion is six‐coordinated by two N and four O atoms from four different Hsae− ligands, yielding a distorted MnO4N2 octahedral environment. Each [MnIII(Hsae)2]+ cationic unit has the Mn atom on an inversion centre and each [MnIII(Hsae)2]+ cation lies about another inversion centre. The chain‐like complex is further extended into a three‐dimensional network structure through Cl⋯H—O hydrogen bonds and C—H⋯π contacts involving the Hsae− rings. 相似文献
11.
Grant J. Sherborne Avetik G. Gevondian Ignacio Funes-Ardoiz Amit Dahiya Christoph Fricke Prof. Dr. Franziska Schoenebeck 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(36):15673-15678
Selective C –C couplings are powerful strategies for the rapid and programmable construction of bi- or multiaryls. To this end, the next frontier of synthetic modularity will likely arise from harnessing the coupling space that is orthogonal to the powerful Pd-catalyzed coupling regime. This report details the realization of this concept and presents the fully selective arylation of aryl germanes (which are inert under Pd0/PdII catalysis) in the presence of the valuable functionalities C−BPin, C−SiMe3, C−I, C−Br, C−Cl, which in turn offer versatile opportunities for diversification. The protocol makes use of visible light activation combined with gold catalysis, which facilitates the selective coupling of C−Ge with aryl diazonium salts. Contrary to previous light-/gold-catalyzed couplings of Ar–N2+, which were specialized in Ar–N2+ scope, we present conditions to efficiently couple electron-rich, electron-poor, heterocyclic and sterically hindered aryl diazonium salts. Our computational data suggest that while electron-poor Ar–N2+ salts are readily activated by gold under blue-light irradiation, there is a competing dissociative deactivation pathway for excited electron-rich Ar–N2+, which requires an alternative photo-redox approach to enable productive couplings. 相似文献
12.
Aicha El Maadi Ali Boukhari Elizabeth M. Holt 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(10):i141-i143
The structure of the title mixed trimetallic diphosphate, K2Sr3Mn2(P2O7)3, is constructed of a three‐dimensional matrix composed of SrO8–10, MnO5 and PO4 polyhedra. The sharing of O atoms between these polyhedra creates tunnels of large dimensions parallel to (010), in which are found columns of K+ ions. Thus, the presence of several cations differing in size in the solid matrix leads to the formation of large tunnels and potential conductivity. 相似文献
13.
Jonghoon Choi Yunho Lee 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(21):7012-7016
A three‐coordinate low‐spin cobalt(I) complex generated using a pincer ligand is presented. Since an empty orbital is sterically exposed at the site trans to the N donor of an acridane moiety, the cobalt(I) center accepts the coordination of various donors such as H2 and PhSiH3 revealing σ‐complex formation. At this low‐spin cobalt(I) site, homolysis of H–H and Si?H bonds preferentially occurs via bimolecular hydrogen atom transfer instead of two‐electron oxidative addition. When the resulting CoII–H species was exposed to N2, H2 evolution readily occurs at ambient conditions. These results suggest single‐electron processes are favored at the structurally rigidified cobalt center. 相似文献
14.
Hongyang Su Lanlan Chen Yizhen Chen Prof. Rui Si Yuting Wu Xiaonan Wu Dr. Zhigang Geng Prof. Wenhua Zhang Prof. Jie Zeng 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(46):20591-20596
Efforts have been devoted to achieving a highly efficient artificial synthesis of ammonia (NH3). Reported herein is a novel Fe-MoS2 catalyst with Fe atomically dispersed onto MoS2 nanosheets, imitating natural nitrogenase, to boost N2 electroreduction into NH3 at room temperature. The Fe-MoS2 nanosheets exhibited a faradic efficiency of 18.8 % with a yield rate of 8.63 μg mgcat.−1 h−1 for NH3 at −0.3 V versus the reversible hydrogen electrode. The mechanism study revealed that the electroreduction of N2 was promoted and the competing hydrogen evolution reaction was suppressed by decorating the edge sites of S in MoS2 with the atomically dispersed Fe, resulting in high catalytic performance for the electroreduction of N2 into NH3. This work provides new ideas for the design of catalysts for N2 electroreduction and strengthens the understanding about N2 activation over Mo-based catalysts. 相似文献
15.
Moritz F. Kuehnel Charles E. Creissen Constantin D. Sahm Dominik Wielend Anja Schlosser Katherine L. Orchard Erwin Reisner 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(15):5113-5117
A precious‐metal‐ and Cd‐free photocatalyst system for efficient H2 evolution from aqueous protons with a performance comparable to Cd‐based quantum dots is presented. Rod‐shaped ZnSe nanocrystals (nanorods, NRs) with a Ni(BF4)2 co‐catalyst suspended in aqueous ascorbic acid evolve H2 with an activity up to 54±2 mmol gZnSe?1 h?1 and a quantum yield of 50±4 % (λ=400 nm) under visible light illumination (AM 1.5G, 100 mW cm?2, λ>400 nm). Under simulated full‐spectrum solar irradiation (AM 1.5G, 100 mW cm?2), up to 149±22 mmol gZnSe?1 h?1 is generated. Significant photocorrosion was not noticeable within 40 h and activity was even observed without an added co‐catalyst. The ZnSe NRs can also be used to construct an inexpensive delafossite CuCrO2 photocathode, which does not rely on a sacrificial electron donor. Immobilized ZnSe NRs on CuCrO2 generate photocurrents of around ?10 μA cm?2 in an aqueous electrolyte solution (pH 5.5) with a photocurrent onset potential of approximately +0.75 V vs. RHE. This work establishes ZnSe as a state‐of‐the‐art light absorber for photocatalytic and photoelectrochemical H2 generation. 相似文献
16.
Dr. Yan Zhang Dr. Margaret A. Hopkins Dr. David J. Liptrot Dr. Hamideh Khanbareh Prof. Pim Groen Xuefan Zhou Prof. Dou Zhang Yinxiang Bao Prof. Kechao Zhou Prof. Chris R. Bowen Dr. David R. Carbery 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(20):7882-7886
We demonstrate that trimethylamine borane can exhibit desirable piezoelectric and pyroelectric properties. The material was shown to be able operate as a flexible film for both thermal sensing, thermal energy conversion and mechanical sensing with high open circuit voltages (>10 V). A piezoelectric coefficient of d33≈10–16 pC N−1, and pyroelectric coefficient of p≈25.8 μC m−2 K−1 were achieved after poling, with high pyroelectric figure of merits for sensing and harvesting, along with a relative permittivity of 6.3. 相似文献
17.
Gemeng Liang Zhibin Wu Christophe Didier Wenchao Zhang Jing Cuan Baohua Li Kuan‐Yu Ko Po‐Yang Hung Cheng‐Zhang Lu Yuanzhen Chen Grzegorz Leniec Sawomir Maksymilian Kaczmarek Bernt Johannessen Lars Thomsen Vanessa K. Peterson Wei Kong Pang Zaiping Guo 《Angewandte Chemie (International ed. in English)》2020,59(26):10594-10602
Spinel LiNi0.5Mn1.5O4 (LNMO) is a promising cathode candidate for the next‐generation high energy‐density lithium‐ion batteries (LIBs). Unfortunately, the application of LNMO is hindered by its poor cycle stability. Now, site‐selectively doped LNMO electrode is prepared with exceptional durability. In this work, Mg is selectively doped onto both tetrahedral (8a) and octahedral (16c) sites in the Fd m structure. This site‐selective doping not only suppresses unfavorable two‐phase reactions and stabilizes the LNMO structure against structural deformation, but also mitigates the dissolution of Mn during cycling. Mg‐doped LNMOs exhibit extraordinarily stable electrochemical performance in both half‐cells and prototype full‐batteries with novel TiNb2O7 counter‐electrodes. This work pioneers an atomic‐doping engineering strategy for electrode materials that could be extended to other energy materials to create high‐performance devices. 相似文献
18.
Tomasz J. Merta Nicholas E. Geacintov Vladimir Shafirovich 《Photochemistry and photobiology》2019,95(1):244-251
The mechanistic aspects of one‐electron oxidation of G‐quadruplexes in the basket (Na+ ions) and hybrid (K+ ions) conformations were investigated by transient absorption laser kinetic spectroscopy and HPLC detection of the 8‐oxo‐7,8‐dihydroguanine (8‐oxoG) oxidation product. The photo‐induced one‐electron abstraction from G‐quadruplexes was initiated by sulfate radical anions (SO4˙?) derived from the photolysis of persulfate ions by 308 nm excimer laser pulses. In neutral aqueous solutions (pH 7.0), the transient absorbance of neutral guanine radicals, G(‐H)˙, is observed following the complete decay of SO4˙? radicals (~10 μs after the actinic laser flash). In both basket and hybrid conformations, the G(‐H)˙ decay is biphasic with one component decaying with a lifetime of ~0.1 ms, and the other with a lifetime of 20–30 ms. The fast decay component (~0.1 ms) in G‐quadruplexes is correlated with the formation of 8‐oxoG lesions. We propose that in G‐quadruplexes, G(‐H)˙ radicals retain radical cation character by sharing the N1‐proton with the O6‐atom of G in the [G˙+: G] Hoogsteen base pair; this [G(‐H)˙: H+G G˙+: G] leads to the hydration of G˙+ radical cation within the millisecond time domain, and is followed by the formation of the 8‐oxoG lesions. 相似文献
19.
Marcus W. Drover Dirk J. Schild Paul H. Oyala Jonas C. Peters 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(43):15650-15657
We report the characterization of an S= iron π‐complex, [Fe(η6‐IndH)(depe)]+ (Ind=Indenide (C9H7?), depe=1,2‐bis(diethylphosphino)ethane), which results via C?H elimination from a transient FeIII hydride, [Fe(η3:η2‐Ind)(depe)H]+. Owing to weak M?H/C?H bonds, these species appear to undergo proton‐coupled electron transfer (PCET) to release H2 through bimolecular recombination. Mechanistic information, gained from stoichiometric as well as computational studies, reveal the open‐shell π‐arene complex to have a BDFEC‐H value of ≈50 kcal mol?1, roughly equal to the BDFEFe‐H of its FeIII?H precursor (ΔG°≈0 between them). Markedly, this reactivity differs from related Fe(η5‐Cp/Cp*) compounds, for which terminal FeIII?H cations are isolable and have been structurally characterized, highlighting the effect of a benzannulated ring (indene). Overall, this study provides a structural, thermochemical, and mechanistic foundation for the characterization of indenide/indene PCET precursors and outlines a valuable approach for the differentiation of a ring‐ versus a metal‐bound H‐atom by way of continuous‐wave (CW) and pulse EPR (HYSCORE) spectroscopic measurements. 相似文献
20.
Yong Lu Xuesen Hou Licheng Miao Lin Li Ruijuan Shi Luojia Liu Jun Chen 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(21):7094-7098
Organic carbonyl compounds show potential as cathode materials for lithium‐ion batteries (LIBs) but the limited capacities (<600 mA h g?1) and high solubility in electrolyte restrict their further applications. Herein we report the synthesis and application of cyclohexanehexone (C6O6), which exhibits an ultrahigh capacity of 902 mA h g?1 with an average voltage of 1.7 V at 20 mA g?1 in LIBs (corresponding to a high energy density of 1533 Wh kg?1 ). A preliminary cycling test shows that C6O6 displays a capacity retention of 82 % after 100 cycles at 50 mA g?1 because of the limited solubility in high‐polarity ionic liquid electrolyte. Furthermore, the combination of DFT calculations and experimental techniques, such as Raman and IR spectroscopy, demonstrates the electrochemical active C=O groups during discharge and charge processes. 相似文献