查看更多>>摘要：With the increasing demand for homoallylic silanes and allylic silanes,the highly efficient and regioselective hydrosilylations of conju-gated dienes are urgently needed.Herein,we developed a Ni-catalyzed regiodivergent hydrosilylation of aromatic conjugated dienes by adjusting the temperature and ligands.Under low temperature(-30 ℃),an eternal-ligand-free system(Ni/t-BuOK)can efficiently facilitate the 3,4-anti-Markovnikov hydrosilylation to provide homoallylic silanes via electrophilic activation process;under room temperature(25 ℃),a ligand-controlled system(Ni/t-BuOK/PPh3)can eventuate the 3,4-Markovnikov hydrosilylation to produce allylic silanes via Chalk-Harrod process.Both systems are compatible with various conjugated dienes and primary silanes in excellent yields and regioselectivities.
查看更多>>摘要：Exploring the physiochemical properties and expanding the applications of actinide-containing materials is paramount to address the escalating challenge of radioactive waste accumulation.However,unlocking the full potential of these materials is largely crippled by the radiotoxicity of the actinides.We report here two porous and luminescent thorium-based metal-organic frameworks(Th-BITD-1 and Th-BITD-2)that serve as a bifunctional platform for sequencing and sensing of radioiodine,a much more radioactive fission prod-uct discharged during the nuclear fuel reprocessing.In particular,Th-BITD-1 displays better iodine uptake performance than Th-BITD-2 via the solution-based process and vapor diffusion with the maximum adsorption capacities of 831 and 1099 mg/g,respectively.Fur-thermore,Th-BITD-1 can function as a highly sensitive luminescence sensor for iodate with a quenching constant(Ksv)of 6.6(5)× 103 M-1 and a detection limit of 2.02 μM,respectively,outperforming 2.96(6)× 103 M-1 and 10.5 μM of Th-BITD-2.Moreover,a positive correlation between the sensing efficacy and the iodate adsorption capacity has been revealed.This work highlights the opportunity in designing novel actinide-based MOFs for their potential applications in radiological fields,e.g.,radionuclide separation and detec-tion.
查看更多>>摘要：Alkynes are versatile synthons in organic synthesis,as well as important structural moieties in bioactive molecules.Recently,transi-tion metal-catalyzed hydroalkynylation of alkenes has been developed with reactive alkenes and alkenes bearing directing groups.However,the regioselective hydroalkynylation of simple alkenes is still challenging.Herein,we have developed a palladium-catalyzed Markovnikov hydroalkynylation of unactivated terminal alkenes,which provides an efficient approach for the synthesis of branched alkynyl compounds under mild conditions.This reaction features excellent functional group tolerance,good reaction yields and ex-cellent regioselectivity.Moreover,the asymmetric hydroalkynylation reaction has also been achieved with moderate enantioselec-tivity by introducing a sterically bulky chiral Pyox ligand.
查看更多>>摘要：Five novel Daphniphyllum alkaloids,named dcalycinumines A-E(1-4,6),and eight previously described Daphniphyllum alkaloids(5,7-13)were isolated from Daphniphyllum calycinum.Compound 1 is the first Daphniphyllum alkaloid possessing a highly rearranged 6/6/6/7/5/6 hexacyclic architecture with a unique 3-methyl-1-azabicyclo[4,4,0]decane ring system.Compound 2 represents a rare diamino Daphniphyllum alkaloid with an unprecedented 6/5/5/6/6/5 carbon skeleton featuring a unique 1-aza-6-azaspiro[4,5]decane unit,whereas 3 also represents a rare diamino Daphniphyllum alkaloid as a possible precursor of 2.Compound 4 is the second exam-ple of C-22-nor yuzurimine-type alkaloids.Their structures and absolute configurations were elucidated by HRESIMS,NMR spectro-scopic analyses,ECD calculations,and single-crystal X-ray diffraction.Moreover,compound 1 showed remarkable antitumor activities,which could inhibit the proliferation,migration and invasion of nasopharyngeal carcinoma cells,and promoted nasopharyngeal carci-noma cells apoptosis.
Li WangRenwei XiaoJingyuan SongLong-Sheng Zheng...
43-47页
查看更多>>摘要：Transition metal-catalyzed asymmetric transfer hydrogenation has been proven to be a powerful approach for the synthesis of chiral alcohols.Herein,a highly efficient and enantioselective transfer hydrogenation of dibenzoheptaheterocyclic ketones catalyzed by an arene-tethered TsDPEN-based Rh(Ⅲ)catalyst has been successfully developed,and a variety of dibenzoheptaheterocyclic ketones were reduced by a 1/1 mixture of formic acid and DBU(1,8-diazabicyclo[5.4.0]undec-7-ene)with high yields and enantioselectivities.With this method,the asymmetric reduction of 7,8-difluorodibenzo[b,e]thiepin-11(6H)-one has been realized,providing the key in-termediate of baloxavir marboxil with＞99％yield and＞99％ee at a substrate/catalyst molar ratio of 1000.
查看更多>>摘要：Seawater electrolysis holds great promise for hydrogen production in the future,while the development of anodic catalysts has been severely hampered by the side-reaction,chloride evolution reaction.In this work,nano-flower-cluster structured CoO@FeSe2/CF catalysts are synthesized via a scalable electrodeposition technique,and the performance is systematically studied.The oxygen evo-lution reaction(OER)overpotential of CoO@FeSe2/CF is 267 mV at 100 mA·cm-2,which is significantly lower than that of the IrO2 catalyst(435 mV).Additionally,the catalyst shows high selectivity for OER(97.9％)and almost no loss of activity after a durability test for 1100 h.The impressive performance is attributed to the dense rod-like structure with abundant active centers after electro-chemical activation and the in-situ generated CoOOH and FeOOH that improve the catalytic activity of the catalyst.The synergistic effect induced by the non-uniform structure endows the catalyst with excellent stability.
查看更多>>摘要：The development of highly efficient non-precious-metal-based electrocatalysts for the hydrogen evolution reaction is imperative for promoting the large-scale application of electrochemical water splitting.Herein,nitrogen/phosphorus co-doped carbon nanorods encapsulated Mo2C nanoparticles(Mo2C@PNC)have been prepared by pre-phosphating treatment in combination of the coordina-tion with polydopamine and the subsequent pyrolysis.The phosphating temperature has a significant effect on the content of phos-phorus within the resultant Mo2C@PNC,and the optimal catalyst delivers superior HER activity with the low overpotential of 104 mV at a current density of 10 mA·cm-2 and good stability for 8 h,which has been theoretically demonstrated to originate from the syn-ergistic effect between P doping and Mo2C induced electron redistribution of nitrogen-doped carbon layer.
查看更多>>摘要：Recently,photodynamic therapy(PDT)has attracted wide attention due to its less susceptibility to drug resistance,broad-spectrum biocidal activity and biosafety in normal tissues.However,the traditional photosensitizers(PSs)face the disadvantage of poor thera-peutic efficacy due to the requirement of an aerobic environment to generate 1O2 through Type Ⅱ pathway.Herein,we designed and synthesized a novel cationic conjugated oligomer oligo(phenylene vinylene)(OPV)and studied its antibacterial photodynamic activity against both Gram-negative Escherichia coli(E.coli)and Gram-positive bacteria methicillin-resistant Staphylococcus aureus(MRSA).Importantly,the OPV can rapidly produce reactive oxygen species(ROS)through double pathways,Type Ⅰ and Ⅱ mechanism under white light irradiation,and efficiently kill E.coli and MRSA at a nanomolar level.The dual type photosensitizing capability makes OPV promising for enhanced PDT to treat pathogens and tumors in complex environments.
查看更多>>摘要：The electrical tunneling sensors have excellent potential in the next generation of single-molecule measurement and sequencing technologies due to their high sensitivity and spatial resolution capabilities.Electrical tunneling signals that have been measured at a high sampling rate may provide detailed molecular information.Despite the extraordinarily large amount of data that has been gathered,it is still difficult to correlate signal transformations with molecular processes,which creates great obstacles for signal analysis.Machine learning is an effective tool for data analysis that is currently gaining more significance.It has demonstrated prom-ising results when used to analyze data from single-molecule electrical measurements.In order to extract meaningful information from raw measurement data,we have combined intelligent machine learning with tunneling electrical signals.For the purpose of analyzing tunneling electrical signals,we investigated the clustering approach,which is a classic algorithm in machine learning.A clustering model was built that combines the advantages of hierarchical clustering and Gaussian mixture model clustering.Addition-ally,customized statistical algorithms were designed.It has been proven to efficiently gather molecular information and enhance the effectiveness of data analysis.
查看更多>>摘要：Ligand-protected gold(Aun)clusters sometimes need the removal of organic ligands to expose more active sites and reduce steric hindrance in catalytic reactions,and large amount of organic and inorganic materials usually need to be employed as supports to anchor Aun clusters through different interaction mechanisms.Whereas,less comprehensive summaries have been provided about the crucial contribution of various supports to the catalytic performance of the supported Aun clusters.Herein,this review firstly summarizes synthesis methods(e.g.,impregnation and encapsulation processes)for the supported Aun cluster catalysts,and then mainly points out specific contributions of support effect in a great diversity of catalytic reactions,as well as deep interaction mech-anisms.Besides,opportunities and challenging issues will be stated towards supported Aun clusters,in terms of improving catalytic performance and structural stability of Aun clusters in the demand of catalysis.
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维普