查看更多>>摘要：Polycatenane gels have attracted extensive attention due to their high degree of freedom and mobility.However,the syntheses of poly[2]catenane gels reported to date all rely on the polymer as the backbone.Herein,we prepared poly[2]catenane gels based on en-tirely sequential assembly of small molecules.Monomer M1 with two unclosed rings was first prepared,which self-assembled to form supramolecular polymers(SPs)via hydrogen bonding and n-n interactions.Upon adding small molecule monomers M2 and M3 with aldehyde groups,ring closing of SPs occurred because the amino groups in the SPs reacted with M2 to form imine bonds.In addition,M3,which had twice the number of aldehyde groups as M2,enabled SPs to ring-close,causing the proceeding of crosslinking process at the same time.Thus linear SPs were transformed into poly[2]catenane gel networks.Due to the presence of hydrogen bonds in the poly[2]catenane gel,the gel also possessed stimulus responsiveness and self-healing properties.
查看更多>>摘要：Cu-catalyzed electrochemical CO2 reduction reaction(CO2RR)and CO reduction reaction(CORR)are of great interest due to their po-tential to produce carbon-neutral and value-added multicarbon(C2+)chemicals.In practice,CO2RR and CORR are typically operated at industrially relevant current densities,making the process exothermal.Although the increased operation temperature is known to af-fect the performance of CO2RR and CORR,the relationship between temperatures and kinetic parameters was not clearly elaborated,particularly in zero-gap reactors.In this study,we detail the effect of the temperature on Cu-catalyzed CO2RR and CORR.Our electro-chemical and operando spectroscopic studies show that high temperatures increase the activity of CO2RR to CO and CORR to C2H4 by enhancing the mass transfer of CO2 and CO.As the rates of these two processes are highly influenced by reactant diffusion,elevating the operating temperature results in high local CO2 and CO availability to accelerate product formation.Consequently,the*CO cover-age in both cases increases at higher temperatures.However,under CO2RR conditions,*CO desorption is more favorable than car-bon-carbon(C—C)coupling thermodynamically at high temperatures,causing the reduction in the Faradaic efficiency(FE)of C2H4.In CORR,the high-temperature-augmented CO diffusion overcomes the unfavorable adsorption thermodynamics,increasing the proba-bility of C—C coupling.
查看更多>>摘要：A novel method for synthesizing α-oxygen organoboron compounds has been developed through acylsilane-based carbene insertion reactions into C—B bonds.As coupling partners,readily available organoboron compounds(alkenyl,allyl,and allenyl B(pin))were em-ployed.Based on the substrates,pure insertion into C—B bonds or insertion followed by a siloxy group rearrangement process(from carbon to boron)would occur,delivering the α-oxygen organoboron compounds with great diversities.Control experiments demon-strated that the electronic effect of the substituents mainly controlled the rearrangement process.Besides,no matter which isomer of substrate(Z or E)was used,the reaction with β-aryl-substituted alkenyl B(pin)affords both isomers of products(Z and E,separable through column chromatography).Trapping experiments indicated the triplet energy transfer process was involved.
查看更多>>摘要：Kagome lattices have garnered significant attention due to their promising applications in catalysis,electronics,and magnetics.Alt-hough many efforts have been paid to the design and synthesis of Kagome lattices,there is a limited focus on constructing this lattice by multiple interaction forces.In this work,we employ 2,7-dibromo-carbazole as precursors to successfully fabricate the two-dimen-sional self-assembly Kagome lattices stabled by multiple interaction forces on Au(111)substrate.Using low-temperature scanning tunneling microscopy,non-contact atomic force microscopy and density functional theory calculation,we visualize and identify the four interaction forces within Kagome lattices:Au—N coordination bonds,Au—H hydrogen bonds,Br—Br halogen bonds,and Br—H hydrogen bonds,respectively.This study provides a basic understanding for designing and constructing more complex Kagome lattices.
查看更多>>摘要：Discovery of unprecedented donor-acceptor patterns can essentially enrich the chemistry of donor-acceptor cyclopropanes.We here-in introduce a concept of vinylogous fluorine stabilizing effect,which guides rational design of a novel donor-acceptor cyclopropane employing gem-difluorovinyl group as the electron donor,namely dFVCP.Application of such dFVCPs in a[3+2]cycloaddition with al-dehydes and a controlled ring-opening polymerization by a Mg(OTf)2/DIPEA/C(sp3)-H initiator system have been demonstrated,providing direct access to fluorine-containing tetrahydrofurans and all-carbon main-chain polymers.
查看更多>>摘要：TAG-assisted peptide synthesis technology enables optimal conservation of Fmoc amino acid raw materials and chemical solvents while eliminating the need for intricate chromatographic purification processes.This work presents a 4,4'-diphenylphosphonoxy di-phenylcarbinol tag-mediated liquid-phase synthesis approach for preparing side-to-tail cyclopeptides macolacin which has strong ac-tivity against gram-negative bacteria,and its 15 analogues containing four N-methylation modified cyclopeptides,as well as an inves-tigation of their structure-activity relationship(SAR).The synthesis of macolacin analogues primarily focuses on the modifications of the N-methylation group of Ile-7 and the tail fatty acyl chain of macolacin.The incorporation of N-methylation for Ile-7,along with the dihalogenated or monohalogenated benzoic acids for tail modification,exhibited remarkable antibacterial efficacy and minimal hepa-tocellular toxicity in vitro.The present study identified an N-methylation-modified antimicrobial cyclopeptide Ma14 that exhibits rapid bactericidal efficacy against A.baumanii,etc.,while showing reduced hepatocellular toxicity.Molecular docking simulations were conducted to investigate the binding of cyclopeptides to the outer membrane protein BamA of A.baumannii.The findings demon-strated the stable binding interactions of the cyclopeptides with the BamA protein and then presented a novel approach to explain the bacteriostatic mechanism of macolacin-based cyclopeptide antibiotics.
查看更多>>摘要：A novel electrocatalyst,Ni-Co/β-Mo2C@C,was rationally designed to enhance the efficiency of the hydrogen evolution reaction(HER)in this work.Assembled with two-dimensional Ni-Co nanosheets onto Mo2C nanorods coated with a thin carbon shell,the catalyst demonstrates remarkable performance,including low overpotential(η10=57 mV)and reduced Tafel slope(63 mV·dec-1)in 0.5 mol·L-1 H2SO4 electrolyte.This innovative design strategy provides abundant active sites and efficient electron/ion transport pathways,effec-tively shortening reactant diffusion distances and enhancing electrocatalytic activity.Additionally,the carbon shell coating protects the catalyst from etching and agglomeration,ensuring its durability.This work presents a promising approach for engineering highly effi-cient metal carbide-based HER catalysts through tailored composition and nanostructure design.
查看更多>>摘要：The EDA complex-mediated reactions involving oxime esters have been few studied.Herein,an EDA complex formed by thiophenolate anion and oxime ester is reported for photoinduced divergent synthesis of thioethers,depending on different types of oxime esters.Operational simplicity,mild reaction conditions,and flexible options of leaving group demonstrate the generality and synthetic utility of this approach.Such an approach can also enable an interesting thiol-catalysis for the synthesis of phenanthridines.
查看更多>>摘要：Designing new materials and architectures to maintain activity and stability requires a better understanding on the anticorrosion dy-namics of nanoparticles.Under-coordinated atoms on the surface of nanoparticles can be protected by deposited shells.Real-time observation on how protective shells grow and play a role is challenging but worthwhile.Here,protective effects of AuCI3 shells on Au nanobipyramids(NBPs)are studied in HAuCI4 aqueous solutions by in-situ liquid cell transmission electron microscopy(LCTEM).This study is the first to observe the formation of Au-AuCI3 core-shell nanostructure and the corresponding anticorrosion behaviors of AuCI3 deposited shell.The presence of CTAB can substantially influence the growth mode and structure of AuCI3 shell,by a direct or indirect way,intervene the dissolution of Au NBP.These growth or dissolution kinetics here revealed at the nanoscale provide insights towards engineering of the surface anticorrosion to pursue Au nanoparticles with improved stability in acidic environment.
查看更多>>摘要：Carbonylation reactions are a valuable synthetic method to construct carbonyl compounds and carbonylation reactions of aryl halides stand out as a highly significant tool for generating carbonyl substituted arenes.However,the important reactions have never been realized in aromatic metallacycles.Herein,we present the first carbonylation reactions of metallaaromatics,specifically alkoxycar-bonylation and aminocarbonylation reactions of an osmapentalyne.During the carbonylation process,the electronic and steric prop-erties of nucleophiles are regarded as critical factors.The alcohols with bulky substituents(isopropanol)require more reaction time and tert-butyl alcohol is inert in the reaction.Comparatively,amines,being stronger nucleophiles,exhibit divergent behaviors.Bulky amines undergo aminocarbonylation,whereas small amines prefer direct nucleophilic additions.Control experiments revealed that the intermediate derived from coupling of metal carbyne with CO plays a significant role in the carbonylation reaction.According to these observations,a divergent pathway for the reaction is proposed.Furthermore,the photophysical properties of these carbon-yl-functionalized osmapentalene complexes are studied,and the maximum absorption peak of compound with a carboxylic group ex-hibits a significant red-shift due to the smaller HOMO-LUMO gap.These findings contribute to expanding the reactivity of metallaaromatics and offer new opportunities for the synthesis of carbonyl-functionalized metallacycles.
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