Jiangxi Normal University

摘要：

Research and industrial interest in radical C-H activation/radical cross-coupling chemistry has continuously grown over the past few decades. These reactions offer fascinating and unconventional approaches toward connecting molecular fragments with high atom- and step-economy that are often complementary to traditional methods. Success in this area of research was made possible through the development of photocatalysis and first-row transition metal catalysis along with the use of peroxides as radical initiators. This Review provides a brief and concise overview of the current status and latest methodologies using radicals or radical cations as key intermediates produced via radical C-H activation. This Review includes radical addition, radical cascade cyclization, radical/radical cross-coupling, coupling of radicals with M-R groups, and coupling of radical cations with nucleophiles (Nu).

ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTOxidative Coupling between Two Hydrocarbons: An Update of Recent C–H FunctionalizationsChao Liu†, Jiwen Yuan†, Meng Gao‡, Shan Tang†, Wu Li†, Renyi Shi†, and Aiwen Lei*†‡View Author Information† College of Chemistry and Molecular Sciences, Institute for Advanced Studies (IAS), Wuhan University, Wuhan 430072, People's Republic of China‡ National Research Center for Carbohydrate Synthesis, Jiangxi Normal University, Nanchang, Jiangxi 330022, People's Republic of China*E-mail: [email protected]Cite this: Chem. Rev. 2015, 115, 22, 12138–12204Publication Date (Web):November 11, 2015Publication History Received7 August 2014Published online11 November 2015Published inissue 25 November 2015https://pubs.acs.org/doi/10.1021/cr500431shttps://doi.org/10.1021/cr500431sreview-articleACS PublicationsCopyright © 2015 American Chemical SocietyRequest reuse permissionsArticle Views24367Altmetric-Citations933LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose SUBJECTS:Catalysts,Cross coupling reaction,Hydrocarbons,Organic compounds,Oxidative coupling Get e-Alerts

ConspectusOxidative cross-coupling has proved to be one of the most straightforward strategies for forming carbon–carbon and carbon–heteroatom bonds from easily available precursors. Over the past two decades, tremendous efforts have been devoted in this field and significant advances have been achieved. However, in order to remove the surplus electrons from substrates for chemical bonds formation, stoichiometric oxidants are usually needed. Along with the development of modern sustainable chemistry, considerable efforts have been devoted to perform the oxidative cross-coupling reactions under external-oxidant-free conditions. Electrochemical synthesis is a powerful and environmentally benign approach, which can not only achieve the oxidative cross-couplings under external-oxidant-free conditions, but also release valuable hydrogen gas during the chemical bond formation. Recently, the electrochemical oxidative cross-coupling with hydrogen evolution reactions has been significantly explored.This Account presents our recent efforts toward the development of electrochemical oxidative cross-coupling with hydrogen evolution reactions. (1) We explored the oxidative cross-coupling of thiols/thiophenols with arenes, heteroarenes, and alkenes for C–S bond formation. (2) Using the strategy of electrochemical oxidative C–H/N–H cross-coupling with hydrogen evolution, we successfully realized the C–H amination of phenols, anilines, imidazopyridines, and even ethers. (3) Employing halide salts as the green halogenating reagents, we developed a clean C–H halogenation protocol under electrochemical oxidation conditions. To address the limitation that this reaction had to carry out in aqueous solvent, we also developed an alternative method that uses CBr4, CHBr3, CH2Br2, CCl3Br, and CCl4 as halogenating reagents and the mixture of acetonitrile and methanol as cosolvent. (4) We also developed an approach for constructing C–O bonds in a well-developed electrochemical oxidative cross-coupling with hydrogen evolution manner. (5) Under mild external-oxidant-free electrochemical conditions, we realized the C(sp2)–H and C(sp3)–H phosphonylation with modest to high yields. (6) We successfully achieved the S–H/S–H cross-coupling with hydrogen evolution under electrochemical oxidation conditions. By anodic oxidation instead of chemical oxidants, the overoxidation of thiols and thiophenols was well avoided. (7) The methods for constructing structurally diverse heterocyclic compounds were also developed via the electrochemical oxidative annulations. (8) We have also applied the electrochemical oxidative cross-coupling with hydrogen evolution strategy to the alkenes difunctionalization for constructing multiple bonds in one step, such as C–S/C–O bonds, C–S/C–N bonds, C–Se/C–O bonds, and C–Se/C–N bonds. We hope our studies will stimulate the research interest of chemists and pave the way for the discovery of more electrochemical oxidative cross-coupling with hydrogen evolution reactions.

Photo-/electrochemical catalyzed oxidative R1-H/R2-H cross-coupling with hydrogen evolution has become an increasingly important issue for molecular synthesis. The dream of construction of C–C/C–X bonds from readily available C–H/X–H with release of H2 can be facilely achieved without external chemical oxidants, providing a greener model for chemical bond formation. Given the great influence of these reactions in organic chemistry, we give a summary of the state of the art in oxidative R1-H/R2-H cross-coupling with hydrogen evolution via photo/electrochemistry, and we hope this review will stimulate the development of a greener synthetic strategy in the near future.

at the atomic scale.

The coronavirus disease (COVID-19) outbreak in December has seen more than 76,000 cases in China, causing more than 3,000 medical staff infections. As the disease is highly contagious, can be fatal in severe cases, and there are no specific medicines, it poses a huge threat to the life and health of nurses, leading to a severe impact on their emotional responses and coping strategies. Therefore, this study will investigate nurses' emotional responses and coping styles, and conduct a comparative study with nursing college students. This study was conducted through the online survey 'questionnaire star' from February 1st to February 20th, 2020 in Anhui Province, using the snowball sampling method to invite subjects. The results found that women showed more severe anxiety and fear than men. Participants from cities exhibited these symptoms more than participants from rural areas, however rural participants experienced more sadness than urban participants. The nearer a COVID-19 zone is to the participants, the stronger the anxiety and anger. The COVID-19 outbreak has placed immense pressure on hospitals and those nurses at the frontline are more seriously affected. Hospitals should focus on providing psychological support to nurses and training in coping strategies.

Based upon advances in theoretical algorithms, modeling and simulations, and computer technologies, the rational design of materials, cells, devices, and packs in the field of lithium-ion batteries is being realized incrementally and will at some point trigger a paradigm revolution by combining calculations and experiments linked by a big shared database, enabling accelerated development of the whole industrial chain. Theory and multi-scale modeling and simulation, as supplements to experimental efforts, can help greatly to close some of the current experimental and technological gaps, as well as predict path-independent properties and help to fundamentally understand path-independent performance in multiple spatial and temporal scales.

As valuable C1 building blocks, isocyanides represent an important class of reactive species and synthons. During the past decades, exhaustive efforts have been devoted to the discovery of highly efficient reactions involving isocyanide on the basis of the development of the Passerini and Ugi reactions. Several types of reactions involving isocyanides have been reported, such as nucleophilic attack, electrophilic addition, imidoylation reactions, and oxidation etc. In this review, recent progress in isocyanide insertion chemistry is presented. Among all isocyanide insertions, two catalytic systems have been developed, that is, Lewis (Brønsted) acid-catalyzed isocyanide insertions and transition-metal-enabled isocyanide insertions, respectively. This review is hence written in the sequence of Lewis (Brønsted) acid-catalyzed isocyanide insertion and transitional metal-enabled isocyanide insertion, where isocyanide insertion into heteroatom-hydrogen bonds, carbon-halogen bonds, carbon-hydrogen bonds, and metal carbenes are summarized.

Abstract The general synthesis and control of the coordination environment of single‐atom catalysts (SACs) remains a great challenge. Herein, a general host–guest cooperative protection strategy has been developed to construct SACs by introducing polypyrrole (PPy) into a bimetallic metal–organic framework. As an example, the introduction of Mg 2+ in MgNi‐MOF‐74 extends the distance between adjacent Ni atoms; the PPy guests serve as N source to stabilize the isolated Ni atoms during pyrolysis. As a result, a series of single‐atom Ni catalysts (named Ni SA ‐N x ‐C) with different N coordination numbers have been fabricated by controlling the pyrolysis temperature. Significantly, the Ni SA ‐N 2 ‐C catalyst, with the lowest N coordination number, achieves high CO Faradaic efficiency (98 %) and turnover frequency (1622 h −1 ), far superior to those of Ni SA ‐N 3 ‐C and Ni SA ‐N 4 ‐C, in electrocatalytic CO 2 reduction. Theoretical calculations reveal that the low N coordination number of single‐atom Ni sites in Ni SA ‐N 2 ‐C is favorable to the formation of COOH* intermediate and thus accounts for its superior activity.

Metal and alloy nanomaterials have intriguing oxidase- and superoxide dismutation-like (SOD-like) activities. However, origins of these activities remain to be studied. Using density functional theory (DFT) calculations, we investigate mechanisms of oxidase- and SOD-like properties for metals Au, Ag, Pd and Pt and alloys Au4-xMx (x = 1, 2, 3; M = Ag, Pd, Pt). We find that the simple reaction-dissociation of O2-supported on metal surfaces can profoundly account for the oxidase-like activities of the metals. The activation (Eact) and reaction energies (Er) calculated by DFT can be used to effectively predict the activity. As verification, the calculated activity orders for series of metal and alloy nanomaterials are in excellent agreement with those obtained by experiments. Briefly, the activity is critically dependent on two factors, metal compositions and exposed facets. On the basis of these results, an energy-based model is proposed to account for the activation of molecular oxygen. As for SOD-like activities, the mechanisms mainly consist of protonation of O2(•-) and adsorption and rearrangement of HO2(•) on metal surfaces. Our results provide atomistic-level insights into the oxidase- and SOD-like activities of metals and pave a way to the rational design of mimetic enzymes based on metal nanomaterials. Especially, the O2 dissociative adsorption mechanism will serve as a general way to the activation of molecular oxygen by nanosurfaces and help understand the catalytic role of nanomaterials as pro-oxidants and antioxidants.

Stretchability and compressibility of supercapacitors is an essential element of modern electronics, such as flexible, wearable devices. Widely used polyvinyl alcohol-based electrolytes are neither very stretchable nor compressible, which fundamentally limits the realization of supercapacitors with high stretchability and compressibility. A new electrolyte that is intrinsically super-stretchable and compressible is presented. Vinyl hybrid silica nanoparticle cross-linkers were introduced into polyacrylamide hydrogel backbones to promote dynamic cross-linking of the polymer networks. These cross-linkers serve as stress buffers to dissipate energy when strain is applied, providing a solution to the intrinsically low stretchability and compressibility shortcomings of conventional supercapacitors. The newly developed supercapacitor and electrolyte can be stretched up to an unprecedented 1000 % strain with enhanced performance, and compressed to 50 % strain with good retention of the initial performance.

Noble metal-based nanomaterials have shown promise as potential enzyme mimetics, but the facet effect and underlying molecular mechanisms are largely unknown. Herein, with a combined experimental and theoretical approach, we unveil that palladium (Pd) nanocrystals exhibit facet-dependent oxidase and peroxidase-like activities that endow them with excellent antibacterial properties via generation of reactive oxygen species. The antibacterial efficiency of Pd nanocrystals against Gram-positive bacteria is consistent with the extent of their enzyme-like activity, that is {100}-faceted Pd cubes with higher activities kill bacteria more effectively than {111}-faceted Pd octahedrons. Surprisingly, a reverse trend of antibacterial activity is observed against Gram-negative bacteria, with Pd octahedrons displaying stronger penetration into bacterial membranes than Pd nanocubes, thereby exerting higher antibacterial activity than the latter. Our findings provide a deeper understanding of facet-dependent enzyme-like activities and might advance the development of noble metal-based nanomaterials with both enhanced and targeted antibacterial activities.

Abstract The design of highly stable, selective and efficient electrocatalysts for CO 2 reduction reaction is desirable while largely unmet. In this work, a series of precisely designed polyoxometalate-metalloporphyrin organic frameworks are developed. Noted that the integration of {ε-PMo 8 V Mo 4 VI O 40 Zn 4 } cluster and metalloporphyrin endows these polyoxometalate-metalloporphyrin organic frameworks greatly advantages in terms of electron collecting and donating, electron migration and electrocatalytic active component in the CO 2 reduction reaction. Thus-obtained catalysts finally present excellent performances and the mechanisms of catalysis processes are discussed and revealed by density functional theory calculations. Most importantly, Co-PMOF exhibits remarkable faradaic efficiency ( > 94%) over a wide potential range (−0.8 to −1.0 V). Its best faradaic efficiency can reach up to 99% (highest in reported metal-organic frameworks) and it exhibits a high turnover frequency of 1656 h −1 and excellent catalysis stability ( > 36 h).

Quantitative analysis is a great challenge in surface-enhanced Raman scattering (SERS). Core-molecule-shell nanoparticles with two components in the molecular layer, a framework molecule to form the shell, and a probe molecule as a Raman internal standard, were rationally designed for quantitative SERS analysis. The signal of the embedded Raman probe provides effective feedback to correct the fluctuation of samples and measuring conditions. Meanwhile, target molecules with different affinities can be adsorbed onto the shell. The quantitative analysis of target molecules over a large concentration range has been demonstrated with a linear response of the relative SERS intensity versus the surface coverage, which has not been achieved by conventional SERS methods.

Composite nanofiber sheets of well-aligned polyacrylonitrile nanofibers (PAN) containing multiwall carbon nanotubes (MWCNTs) were prepared by electrospinning a MWCNT-suspended solution of PAN in dimethyl formamide using a moving collector. Scanning electron microscopy, atomic force microscopy, transmission electron microscopy (TEM), IR spectroscopy, Raman spectroscopy, X-ray scattering, and the Instron test were used to characterize the nanofiber sheets. TEM observation showed the MWCNTs were parallel and oriented along the axes of the nanofibers. The mechanical properties of the composite nanofibers were reinforced by MWCNT fillers. Carbonization processes showed that a higher concentration of MWCNTs effectively resisted heat shrinkage of the composite nanofiber sheet.

As promising high-capacity cathode materials for Na-ion batteries, O3-type Na-based metal oxides always suffer from their poor air stability originating from the spontaneous extraction of Na and oxidation of transition metals when exposed to air. Herein, a combined structure modulation is proposed to tackle concurrently the two handicaps via reducing Na layers spacing and simultaneously increasing valence state of transition metals. Guided by density functional theory calculations, we demonstrate such a modulation can be subtly realized through cosubstitution of one kind of heteroatom with comparable electronegativity and another one with substantially different Fermi level, by adjusting the structure of NaNi0.5Mn0.5O2 via Cu/Ti codoping. The as-obtained NaNi0.45Cu0.05Mn0.4Ti0.1O2 exhibits an increase of 20 times in stable air-exposure period and 9 times in capacity retention after 500 cycles, and even retains its structure and capacity after being soaked in water. Such a simple and effective structure modulation reveals a new avenue for high-performance O3-type cathodes and pushes the large-scale industrialization of Na-ion batteries a decisive step forward.

Photochemistry has ushered in a new era in the development of chemistry, and photoredox catalysis has become a hot topic, especially over the last five years, with the combination of visible-light photoredox catalysis and radical reactions. A novel, simple, and efficient radical oxidative decarboxylative coupling with the assistant of the photocatalyst [Ru(phen)3 ]Cl2 is described. Various functional groups are well-tolerated in this reaction and thus provides a new approach to developing advanced methods for aerobic oxidative decarboxylation. The preliminary mechanistic studies revealed that: 1) an SET process between [Ru(phen)3 ](2+) * and aniline play an important role; 2) O2 activation might be the rate-determining step; and 3) the decarboxylation step is an irreversible and fast process.

Abstract Supercapacitors can harvest electrical energy from intermittent sources and transfer it quickly, but their specific energy must be raised if they are applied to efficiently power wearable and flexible electronics, as well as larger equipment. However, the remaining big gap between the lab research and practical applications seriously hinders the further progress of advanced supercapacitors, especially for electrode materials. Consequently, from a commercial/usable perspective, a clear guideline from lab research to commercialization is highly desired for bringing advanced supercapacitors from basic research into reality. This review focuses on the key factors of advanced supercapacitors from lab research to commercialization and summarizes recent progress in the field of supercapacitors as well as outlines key perspectives for future research. First, the several energy storage mechanisms are illustrated for building better supercapacitors. Then, the up‐to‐date key achievements and progresses of smart methods toward high‐energy supercapacitors and effective strategies for commercial‐level mass‐loading as well as high packing density electrodes are summarized and commented upon. Also, integrated systems of supercapacitors and application fields of commercial supercapacitors are also highlighted. Subsequently, future research directions are presented here to guide research toward the commercialization of advanced supercapacitors.

Abstract Accelerating the construction of the green supply chain system and improving the efficiency of the green supply chain is the key to promoting the high-quality development of enterprises. In view of this, based on stakeholder theory, higher order theory and expectancy theory, this study focuses on the impact of corporate social responsibility (CSR) on corporate green supply chain efficiency (GSCE) and the moderating role of chief executive officer (CEO) narcissism. A regression analysis of the observed sample reveals that CSR significantly enhances GSCE. Further decomposing CSR into internal CSR and external CSR to reveal the impact of different types of CSR on GSCE, we find that internal CSR fulfillment has a significant positive impact on GSCE, and this relationship is strengthened when CEOs are narcissistic. Furthermore, external CSR has a significant negative impact on GSCE, and this relationship is also strengthened by CEO narcissism. The main contribution of this paper is to study the relationship between CSR and green supply chain efficiency, decompose CSR into internal and external CSR, enrich the research on the intrinsic mechanism of value creation of CSR. It also enriches the research in the context of CSR from the perspective of CEO personality traits, providing new ideas and suggestions for manager selection and corporate greening governance in practice.