查看更多>>摘要：Metallacyclopentadienes are important metallacycles and regarded as intermediates in many reactions,therefore,new methods to achieve them are anticipated.In this study,a formal[3+2]method,through the reactions of an osmapentalyne with benzyl carbani-ons,was developed.The reactions underwent a nucleophilic attack of carbanions to the Os≡C bond,followed by C—H activation to form the five-membered osmacyclopentadiene ring.Most of the reactions were carried out at room temperature,the substituents on the aromatic rings of benzyl carbanions are diverse,and the resulting products contain an Os—H bond,representing a novel type of 1OC-carbolong complexes.This work provides a new convenient route to construct metallacyclopentadienes,which is expected to further promote the development of such á type of substances.
查看更多>>摘要：Helicobacter pylori(H.pylori)infection is a threat to human health.The lipopolysaccharide(LPS)O-antigen holds promise for devel-oping vaccines.It is meaningful to explore the immunological activity of oligosaccharides with different lengths and frameshifts for antigen development.Herein,a glycan library of H.pylori O2 O-antigen containing eight fragments is constructed.After screening with anti-H.pylori O2 LPS sera and patients'sera by glycan microarray,the disaccharide HPO2G-2b and trisaccharide HPO2G-3a show strong antigenicity and then are separately conjugated with carrier protein CRM197.Both glycoconjugates elicit a robust im-munoglobulin G(IgG)immune response in rabbits.The anti-HPO2G-3a IgG antibodies possess a much stronger binding affinity with the LPS and bacteria of H.pylori O2 than the anti-HPO2G-2b IgG antibodies.There is no cross-reaction between both sera IgG anti-bodies with LPS and bacteria of H.pylori O1,O6,and E.coli.The results demonstrate the trisaccharide HPO2G-3a is a promising can-didate for H.pylori vaccine development.
查看更多>>摘要：Since 1986,the donor-acceptor(D:A)heterojunction has been regarded a necessity for high-efficiency organic photovoltaics(OPVs),due to its unique advantage in compensating the intrinsic limitations of organic semiconductors,such as high exciton binding energy and poor ambipolar charge mobility.While this adversely causes tremendous non-radiative charge recombination and instability is-sues,which currently become the most critical limits for commercialization of OPVs.Here,we present a concept-to-proof study on the potential of D:A heterojunction free OPV by taking advantage of recent progress of non-fullerene acceptors.First,we demonstrate that the"free carriers"can be spontaneously generated upon illumination in an NFA,i.e.,the 6TIC-4F single layer.Second,the 6TIC-4F layer also exhibits good ambipolar charge transporting property.These exceptional characteristics distinguish it from the traditional organic semiconductors,and relieve it from the reliance of D:A heterojunction to independently work as active layer.As a result,the subsequent OPV by simply sandwiching the 6TIC-4F layer between the cathode and anode yields a considerably high power conver-sion efficiency～1％.Moreover,we find the D:A heterojunction free device exhibits two order of magnitude higher electrolumines-cence quantum efficiency and significantly reduced Voc loss by 0.16 eV compared to those of the D:A BHJ structure,validating its promise for higher efficiency in the future.Therefore,our work demonstrates the possibility of using D:A heterojunction-free device structure for high performance,that can potentially become the next game changer of OPV.
查看更多>>摘要：A series of 3-acyl-substituted isoindolinone derivatives were synthesized in a one-pot manner via the reaction of o-bromobenzalde-hydes,isocyanides,and carboxylic acids in the presence of palladium catalyst and base.The reaction employing easily available start-ing materials features simple operation and high efficiency.The mechanistic study showed that the reaction might undergo 1)Pd-catalyzed[3+2]cyclization of o-bromobenzaldehyde with isocyanide and the re-insertion of another molecule of isocyanide,2)ad-dition of carboxylic acid to in situ formed ketenimine followed by a rearrangement relay to give 3,3-diacyl-substituted isoindolinone derivative.Further transformations of the obtained products through decarbonylation could also be realized.
Ernest KorantengZhen-Cao ShuYi-Yin LiuQian Yang...
264-270页
查看更多>>摘要：Ureas are widely used in drugs,materials and catalysts because of their diamide structure,which can form strong hydrogen bonds.Therefore,it is of great scientific significance to develop efficient and green methods for the synthesis of urea compounds,especially unsymmetrical ureas.Here,we have disclosed novel and highly efficient three-component coupling reactions of organic halides,so-dium cyanate and amines enabled by nickel/photoredox dual catalysis for the preparation of unsymmetrical ureas.The reaction fea-tures simple and safe operations,broad substrate scopes,and product diversities.It allows the facile synthesis of N-aryl/vinyl ureas from readily available,user-friendly feedstocks under mild conditions(27 examples,36％—98％yields).In addition,this method is further derived to alcohols as nucleophiles to synthesize a series of carbamates(15 examples,40％—95％yields).The mechanism experiment shows that the isocyanate produced by the coupling of halide and sodium cyanate may be the key intermediate in this reaction.
查看更多>>摘要：A phosphine-catalyzed[4+3]annulation between dinucleophilic indole derivatives and Morita-Baylis-Hillman(MBH)carbonates was discovered by using the N1 and N4'/C4'nucleophilicities of the indole precursors,in which indoles act as four atom synthons.This protocol provides an efficient and facile access to indole-1,2-fused 1,4-diazepinones and azepines in good to high yields in one step,which illustrates potential synthetic utilities in drug discovery.
查看更多>>摘要：N-Methylation of amines with CO2 and H2 is a potential approach for CO2 utilization because N-methylated amines can be used as solvents and organic intermediates.In2O3-supported Cu(Cu/In2O3)acts as an effective heterogeneous catalyst for N-methylation re-action of N-methylaniline(MA)with CO2 and H2,showing higher N,N-dimethylaniline(DMA)selectivity than other supported Cu cat-alysts.On one hand,the dispersion of Cu can be improved by the defective In2O3 support.On the other hand,In2O3 support is active in the dissociative adsorption of CO2 through C—O bond breaking.In addition,the H2 dissociation ability of In2O3 can also be en-hanced by Cu.The combination of Cu and In2O3 is effective in the activation of CO2,the adsorption of intermediate N-methyl-formanilide(MFA),the hydrogenation of MFA to DMA and the prohibition of C—N bond cleavage side reactions,thereby enhancing the reaction rate of MA conversion and the selectivity to DMA.
查看更多>>摘要：The development of host-guest MOF luminescent composites has attracted considerable attention.However,it is still a challenge to reasonably design large scale conjugated polycarboxylic acids metal-organic framework(MOF)and modulate donor-acceptor interac-tion.Herein,a series of isostructural 3D porous lanthanide MOF[Ln2(BINDI)0.5(NO3)(DMA)(H2O)]·DMA·2.5H2O(Ln=La(1),Ce(2),Pr(3)and Nd(4);H4BINDI(N,N'-bis(5-isophthalic acid)-1,4,5,8-naphthalenediimide)were synthesized.Considering the electron-deficient performances of Ln-BINDI MOFs,D-A type composites Ln-MOFs(1-4@H4TBAPy)were prepared via the incorporation of electron-rich H4TBAPy(1,3,6,8-tetrakis(p-benzoic acid)pyrene),which more improved the luminescence performance of complexes 1-4 and can be used as fluorescence sensors for the detection of nitro compounds and aldehydes.High sensitivity of 1@H4TBAPy towards pNBA,pNA PNP,DNP,and TNP could be achieved through hydrogen bond interactions between MOF and analytes,as well as the π-π interaction between H4TBAPy and the naphthalene ring of BINDI,thus the fluorescence quenching efficiency of 1@H4TBAPy was better than that of the complex 1.In addition,it is found that 1@H4TBAPy has high selectivity and sensitivity to aromatic aldehyde SA,5-Mesal and HMBA.Such strategy to enhance the emission of NDI based Ln-BINDI MOFs,will open up an avenue to obtain more fluorescent MOFs for sensing.
查看更多>>摘要：Palladium-catalyzed Mizoroki-Heck reaction is a powerful and efficient method for construction of Csp2-Csp2 bonds.Herein,four pal-ladium complexes(Ⅰ-Ⅳ)with N,O-bidentate ligands(L1—L4)based on N-oxide units from cyclic secondary amines were easily syn-thesized and successfully applied in Mizoroki-Heck reaction of aryl bromides with electron-deficient olefins.X-ray diffraction anal-yses indicated the palladium(Ⅱ)atom of Ⅱ took the distorted square planar geometry and was four-coordinated by nitrogen and ox-ygen atoms from two ligands(L2).Two free chloride ions were presented as counter anions in complex Ⅱ.But the palladium(Ⅱ)center of Ⅳ was coordinated by nitrogen and oxygen atoms from one ligand(L4)as well as two chlorine atoms,which exhibited the nearly square-planar geometry.The study on catalytic properties of palladium complexes revealed that complex Ⅱ exhibited high activity superior to the other complexes.The coupling reactions of a series of aryl bromides and olefin derivatives proceeded in the presence of 2-5 mol％palladium complex Ⅱ,giving the desired products in good to excellent yields.The advantages of this method such as good compatibility of functional groups,high yields,and short reaction times made it more attractive for constructing Csp2-Csp2 bonds in the synthesis of functional molecules and materials.
查看更多>>摘要：Covalent triazine framework nanosheets(CTF NSs),an emerging class of two-dimensional nanomaterials,have received great atten-tion due to their abundant active sites,permanent porosity,molecular structural diversity,superior chemical/thermal stability,and short charge diffusion path,enabling technological breakthroughs in a myriad of applications.The forefront developments and appli-cations of CTF NSs as photocatalysts and electrochemical electrodes have conferred superior performance and made great impact in the field of energy and advanced catalysis.This forward-looking review aims to summarize the research trends,synthesis,properties of CTF NSs and their CTF counterpart,and highlight their progress in applications with respect to energy storage and conversion de-vices.Finally,the current challenges and future perspectives for CTF NSs are also presented.
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