The heterogeneity of active sites is the main obstacle for selectivity control in heterogeneous catalysis.Single atom catalysts（SACs） with homogeneous isolated active sites are highly desired in chemoselective trans...The heterogeneity of active sites is the main obstacle for selectivity control in heterogeneous catalysis.Single atom catalysts（SACs） with homogeneous isolated active sites are highly desired in chemoselective transformations. In this work, a Pd1/ZnO catalyst with single‐atom dispersion of Pd active sites was achieved by decreasing the Pd loading and reducing the sample at a relatively low temperature. The Pd1/ZnO SAC exhibited excellent catalytic performance in the chemoselective hydrogenation of acetylene with comparable chemoselectivity to that of PdZn intermetallic catalysts and a greatly enhanced utilization of Pd metal. Such unusual behaviors of the Pd1/ZnO SAC in acetylene semi‐hydrogenation were ascribed to the high‐valent single Pd active sites, which could promote electrostatic interactions with acetylene but restrain undesired ethylene hydrogenation via the spatial restrictions of σ‐chemical bonding toward ethylene.展开更多
The chemoselectivities of PdCl2 and CuCl2-catalyzed oligomerization of 3, 3-dimethyl-butyne: 1, 3, 5-tri-tert-butylbenzene, 2, 2, 7, 7-tetramethyl-3, 6-dichloro-3, 5-octadiene and 2, 2, 7, 7- tetramethyl-3, 5-octadiyn...The chemoselectivities of PdCl2 and CuCl2-catalyzed oligomerization of 3, 3-dimethyl-butyne: 1, 3, 5-tri-tert-butylbenzene, 2, 2, 7, 7-tetramethyl-3, 6-dichloro-3, 5-octadiene and 2, 2, 7, 7- tetramethyl-3, 5-octadiyne were obtained, respectively, by regulating the polarity of the solvent.展开更多
Ketenimine zwitterionic salt(KZS),a novel and stable ketenimine precursor,is still underexplored in the realm of chemical synthesis.In this study,we demonstrate the transformation of pyrrole derivatives through the cy...Ketenimine zwitterionic salt(KZS),a novel and stable ketenimine precursor,is still underexplored in the realm of chemical synthesis.In this study,we demonstrate the transformation of pyrrole derivatives through the cyclization of KZS withα-aminoketones.The diastereoselectivity of this reaction is influenced by the solvent,enabling the isolation of 3-hydroxypyrrolidine diastereomers with the highest reported dr value of 21:1.Furthermore,the chemoselectivity is modulated by the choice of base,yielding 2-aminopyrrole derivatives as the major products.This research offers a sustainable approach to harnessing the potential of KZS in organic synthesis,contributing to a greener chemical process.展开更多
Lewis base catalyzed and Brønsted acid controlled chemodivergent electrophilic selenofunctionalizations of alkynes were developed for the first time.Various selenium-containing tetrasubstituted alkenes were readi...Lewis base catalyzed and Brønsted acid controlled chemodivergent electrophilic selenofunctionalizations of alkynes were developed for the first time.Various selenium-containing tetrasubstituted alkenes were readily obtained in moderate to excellent yields with complete E/Z selectivities.As the substrates were 1-ethynyl naphthol derivatives,linear selenium-containing tetrasubstituted alkenes were produced via intermolecular oxygen nucleophilic attack in the absence of acid additive;in contrast,cyclic selenium-containing tetrasubstituted alkenes were generated through intramolecular carbon nucleophilic capture with the addition of Brønsted acid.展开更多
Solvent-free reactions of aromatic aldehydes with three representative ketones,including acetophenone,acetone and cyclohexanone,have been examined under the catalysis of a low-cost inorganic base system consisting of ...Solvent-free reactions of aromatic aldehydes with three representative ketones,including acetophenone,acetone and cyclohexanone,have been examined under the catalysis of a low-cost inorganic base system consisting of NaOH and K2CO3.It was found that the chemoselectivity of the reactions is in close relationship with the composition of the reactants and the doublecomponent catalyst.Under the optimized experimental conditions,1,2,3,4,5-pentasubstituted cyclohexanols,α,β-unsaturated ketones and Claisen-Schmidt bicondensation products were obtained in high yields.Two Kostanecki's triketones were separated,The composition and structure were affirmed by X-ray crystallographic analysis.展开更多
A novel and readily available binaphthyl-based fluorescent probe(S)-1 was designed and synthesized.(S)-1 can be used to not only chemoselectively discriminate 3 basic amino acids out of common amino acids,but also ena...A novel and readily available binaphthyl-based fluorescent probe(S)-1 was designed and synthesized.(S)-1 can be used to not only chemoselectively discriminate 3 basic amino acids out of common amino acids,but also enantioselectively recognize histidine.Encouragingly,enantioselective imaging of histidine in cells was achieved for the first time by the probe(S)-1.These performances endowed it potential application in the chiral analysis of basic amino acids in asymmetric synthesis and cell imaging for diagnosis of diseases caused by racemization of histidine.Nuclear magnetic resonance(NMR)and mass spectrometry investigations suggested that different reaction extent of(S)-1 with L/D-histidine and different product structures generated the observed enantioselective fluorescent response.The molecular structures and thermodynamic stability of the complexes,formed from(S)-1+Zn2+and enantiomers of histidine,were calculated by Gaussian 16 based on density functional theory(DFT)to validate the above action mechanism.展开更多
Chemoselective,living/controlled polymerizations of allyl methacrylate(AMA) and vinyl methacrylate(VMA) with/without methyl methacrylate(MMA) by using the phosphonium ylide/organoaluminum based Lewis pairs(LPs) have b...Chemoselective,living/controlled polymerizations of allyl methacrylate(AMA) and vinyl methacrylate(VMA) with/without methyl methacrylate(MMA) by using the phosphonium ylide/organoaluminum based Lewis pairs(LPs) have been realized.The P-ylide-2/AIMe(BHT)_(2)(Pylide-2=Ph_(3)P=CHMe and BHT=2,6-iBu_(2)-4-MeC_(6)H_(2)O) was demonstrated to be superior by which homopolymers PAMAs(M_(n)=27.6-111.5kg/mol and ■=1.14-1.25) and PVMAs(M_(n)=28.4-78.4 kg/mol and ■=1.12-1.18) and block copolymers PMMA-b-PAMA,PAMA-b-PVMA,PAMA-bPMMA,PMMA-b-PAMA-b-PMMA,PAMA-b-PMMA-b-PAMA,and PAMA-b-PVMA-b-PAMA were synthesized.In the polymerizations,all of the monomers were reacted by the conjugated ester vinyl groups leaving intactly the nonconjugated acryloxy groups.The pendant acryloxy groups attached to the main chain enable further to post-functionalization by the AIBN-induced radical "thiol-ene" reaction using PhCH_(2)SH.The thiolether side group-containing polymers PAMA-SCH_(2)Ph and PAMA-SCH_(2)Ph-b-PMMA-b-PAMA-SCH_(2)Ph were thus prepared.展开更多
Spermatogenesis, maturation, capacitation and fertilization are precisely regulated by glycosylation. However, the relationship between altered glycosylation patterns and the onset and development of reproductive diso...Spermatogenesis, maturation, capacitation and fertilization are precisely regulated by glycosylation. However, the relationship between altered glycosylation patterns and the onset and development of reproductive disorders is unclear, mainly limited by the lack of in situ imaging techniques for spermatozoa glycosylation. We developed an efficient and highly specific spermatozoa glycan imaging technique based on the robust chemoselective labeling of sialic acid(Sia) and N-acetyl-D-galactosamine(Gal/GalNAc). We further proposed a “tandem glycan chemoselective labeling” strategy to achieve simultaneous imaging of two types of glycans on spermatozoa. We applied the developed method to the spermatozoa from oligozoospermic patients and diabetic mice and found that these spermatozoa showed higher levels of Sia and Gal/Gal NAc expression than the normal groups. Moreover, spermatozoa from diabetic mice showed a severe decrease in number, viability, and forward motility, suggesting that in vivo glucose metabolism disorders may lead to an elevated level of spermatozoa glycosylation and have a correlation with the development of oligoasthenotspermia. Our work provides a research tool to reveal the relationship between glycosylation modification and spermatozoa quality, and a promising clue for the development of glycan-based reproductive markers.展开更多
Carbon monoxide(CO)is a vital intracellular gas messenger known for its cytoprotective and homeostatic properties.It plays a pivotal role in a myriad of biological processes.Therefore,the precise detection of CO is of...Carbon monoxide(CO)is a vital intracellular gas messenger known for its cytoprotective and homeostatic properties.It plays a pivotal role in a myriad of biological processes.Therefore,the precise detection of CO is of paramount importance in unraveling the intricacies of pathological mechanisms and advancing the development of disease diagnosis.We herein introduce NFCOP,a state-of-the-art near-infrared(NIR)turn-on fluorescence(FL)probe that has been meticulously designed for highly sensitive,swift and selective imaging of CO.The NFCOP response occurred rapidly with CO,within just 10 s,and the calculated detection limit for CO was determined to be 0.32μmol/L.Further investigations conducted at the cellular level and in vivo demonstrated that NFCOP possesses high sensitivity and selectivity for imaging CO.展开更多
The chemoselective hydrogenation of structurally diverse nitroaromatics is a challenging process.Generally,catalyst activity tends to decrease when excellent selectivity is guaranteed.We here present a novel photocata...The chemoselective hydrogenation of structurally diverse nitroaromatics is a challenging process.Generally,catalyst activity tends to decrease when excellent selectivity is guaranteed.We here present a novel photocatalyst combining amino-functionalized carbon dots(N-CDs)with copper selenite nanoparticles(N-CDs@CuSeO_(3))for simultaneously improving selectivity and activity.Under visible light irradiation,the prepared N-CDs@CuSeO_(3)exhibits 100%catalytic selectivity for the formation of 4-aminostyrene at full conversion of 4-nitrostyrene in aqueous solvent within a few minutes.Such excellent photocatalytic performance is mainly attributed to the precise control of the hydrogen species released from the ammonia borane by means of light-converted electrons upon N-CDs@CuSeO_(3).Besides,the defect states at the interface of N-CDs and CuSeO_(3)enable holes to be trapped for promoting separation and transfer of photogenerated charges,allowing more hydrogen species to participate in catalytic reaction.展开更多
Metal-organic-framework （MOF）-based materials with novel physicochemical properties have emerged as promising catalysts for various hydrogenation reactions. In addition to metal clusters and multifunctional organic...Metal-organic-framework （MOF）-based materials with novel physicochemical properties have emerged as promising catalysts for various hydrogenation reactions. In addition to metal clusters and multifunctional organic ligands, MOF-based catalysts can incorporate other functional species, and thus provide various active sites for hydrogenation processes. The structural properties of the catalysts play significant roles in enhancing the interactions among the reactants, products, and catalytic sites, which can be rationally designed. Because of the synergistic effects between the ac-tive sites and the structural properties, MOF-based catalysts can achieve higher activities and selec- tivities in hydrogenation reactions than can be obtained using traditional heterogeneous catalysts. This review provides an overview of recent developments in MOF-based catalysts in the hydro-genation of alkenes, alkynes, nitroarenes, cinnamaldehyde, furfural, benzene, and other compounds. Strategies for improving the catalytic performances of MOF-based catalysts are discussed as well as the different active sites and structural properties of the catalysts.展开更多
An efficient and low-cost supported Pt catalyst for hydrogenation of niroarenes was prepared with colloid Pt precursors andα-Fe2O3 as a support.The catalyst with Pt content as low as 0.2 wt%exhibits high activities,c...An efficient and low-cost supported Pt catalyst for hydrogenation of niroarenes was prepared with colloid Pt precursors andα-Fe2O3 as a support.The catalyst with Pt content as low as 0.2 wt%exhibits high activities,chemoselectivities and stability in the hydrogenation of nitrobenzene and a variety of niroarenes.The conversion of nitrobenzene can reach 3170 molconv h^–1 molPt^–1 under mild conditions(30°C,5 bar),which is much higher than that of commercial Pt/C catalyst and many reported catalysts under similar reaction conditions.The spatial separation of the active sites for H2 dissociation and hydrogenation should be responsible for the high chemoselectivity,which decreases the contact possibility between the reducible groups of nitroarenes and Pt nanoparticles.The unique surface properties ofα-Fe2O3 play an important role in the reaction process.It provides active sites for hydrogen spillover and reactant adsorption,and ultimately completes the hydrogenation of the nitro group on the catalyst surface.展开更多
Ferrous methanesulfonate catalysing the conversion of aromatic, heteroaromatic, unsaturated, and aliphatic aldehydes to 1,1- diacetates at room temperature under solvent-free condition has been developed. The catalyti...Ferrous methanesulfonate catalysing the conversion of aromatic, heteroaromatic, unsaturated, and aliphatic aldehydes to 1,1- diacetates at room temperature under solvent-free condition has been developed. The catalytic activity of seventeen metal methanesulfonates was compared under the same condition, ferrous methanesufonate proved to be the best. It can be easily recovered and reused for several times without distinct deterioration in catalytic activity. During the competitive protection between a ketone and an aldehyde group with Ac20, 1,1-diacetate formed exclusively with the aldehyde group. 2009 Min Wang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.展开更多
The novel efficient procedure has been developed for the conjugate addition of amines to electron deficient alkenes.A series of hydrotalcite-like materials were synthesized as catalyst for the conjugate addition of am...The novel efficient procedure has been developed for the conjugate addition of amines to electron deficient alkenes.A series of hydrotalcite-like materials were synthesized as catalyst for the conjugate addition of amines and alkenes.After optimizing the reaction conditions,ZnAl-LDHs (3:1) was chosen as the best catalyst for the reaction.The results showed that the catalyst worked very well for the conjugate addition of amines to electron deficient alkenes with the excellent yields in several minutes.Operational simplicity,no solvent,low cost of the catalyst,high yields,reusability,excellent chemoselectivity,wide applicability are the key features of this method.展开更多
Methanol is a safe, economic and easy-to-handle hydrogen source. It has rarely been used in transfer hydrogenation reactions, however. We herein report that a cyclometalated rhodium complex, rhodacycle, catalyzes high...Methanol is a safe, economic and easy-to-handle hydrogen source. It has rarely been used in transfer hydrogenation reactions, however. We herein report that a cyclometalated rhodium complex, rhodacycle, catalyzes highly chemoselective hydrogenation of α,β-unsaturated ketones with methanol as the hydrogen source. A wide variety of chalcones, styryl methyl ketones and vinyl methyl ketones, including sterically demanding ones, were reduced to the saturated ketones in refluxing methanol in a short reaction time, with no need for inter gas protection, and no reduction of the carbonyl moieties was observed. The catalysis described provides a practically easy and operationally safe method for the reduction of olefinic bonds in α,β-unsaturated ketone compounds.展开更多
A convenient, environmentally benign, and highly efficient protocol for the preparation of N-arylhydroxylamines from the corresponding nitroarenes in a Zn/HCOONH4/CH3CN system under ultrasound is described The advanta...A convenient, environmentally benign, and highly efficient protocol for the preparation of N-arylhydroxylamines from the corresponding nitroarenes in a Zn/HCOONH4/CH3CN system under ultrasound is described The advantages of the present method include high chemoselectivity, simple and practical work-up procedure and high yield.展开更多
The utilization of readily available amino acids,which is not only an oxygen nucleophile but also a nitrogen nucleophile,in palladium-catalyzed allylic substitution is realized under mild conditions.The chemoselectivi...The utilization of readily available amino acids,which is not only an oxygen nucleophile but also a nitrogen nucleophile,in palladium-catalyzed allylic substitution is realized under mild conditions.The chemoselectivity and multiple allylation are controlled by adjusting the reaction conditions.This represents the first example of this convenient access to valuable N,O-diallylated amino acids.Under the title conditions,a range of amino acids(α-,β-,γ-)and dipeptides can be readily converted in to the corresponding allylic products with excellent yields(67 examples,up to 99%yield)as well as good functional group tolerance.展开更多
Both sulfur and fluorine play important roles in organic synthesis, the life science, and materials science.The direct incorporation of these elements into organic scaffolds with precise control of the oxidation state...Both sulfur and fluorine play important roles in organic synthesis, the life science, and materials science.The direct incorporation of these elements into organic scaffolds with precise control of the oxidation states of sulfur moieties is of great significance. Herein, we report the highly selective electrochemical vicinal fluorosulfenylation and fluorosulfoxidation reactions of alkenes, which were enabled by the unique ability of electrochemistry to dial in the potentials on demand. Preliminary mechanistic investigations revealed that the fluorosulfenylation reaction proceeded through a radical-polar crossover mechanism involving a key episulfonium ion intermediate. Subsequent electrochemical oxidation of fluorosulfides to fluorosulfoxides were readily achieved under a higher applied potential with the adventitious H;O in the reaction mixture.展开更多
The catalytic hydrogenation of halonitroarenes to haloanilines is a green and sustainable process for the production of key nitrogen-containing intermediates in fine chemical industry.Chemoselective hydrogenation pose...The catalytic hydrogenation of halonitroarenes to haloanilines is a green and sustainable process for the production of key nitrogen-containing intermediates in fine chemical industry.Chemoselective hydrogenation poses a significant challenge,which requires the rational design of the catalysts with proper hydrogenation ability for nitro group and simultaneously preventing dehalogenation of halogen group.Herein,a highly effective Rh@Al_(2)O_(3)@C single-atom catalyst(SAC)was developed for the hydrogenation of m-chloronitrobenzene(m-CNB)to m-chloroaniline(m-CAN),through an in-situ grafting of metal during the assembly of MIL-53(Al),followed by confined pyrolysis.Extensive characterizations reveal an exquisite structure of the Rh@Al_(2)O_(3)@C,containing atomically dispersed Rh sites onto Al_(2)O_(3) confined by the amorphous carbon.The five-coordinated aluminum(Al^(Ⅴ))species are essential for achieving the atomic dispersion of Rh atoms,providing the unsaturated coordinative sites for metal.Compared to the benchmark Rh/γ-Al_(2)O_(3) and Rh/C nanocatalysts,the Rh@Al_(2)O_(3)@C SAC affords an excellent turnover frequency of 2317 molm-CNB·molRh^(–1)·h^(–1),the highest value to date in heterogeneous catalyst systems for the hydrogenation of m-CNB at 313 K and 20 bar H2,together with a sustained selectivity to m-CAN(~98%)during five consecutive runs.The superior catalytic performance of the Rh@Al_(2)O_(3)@C is attributed to a proper modulation of electronic structure of hydrogenation metal by forming SAC,together with an enhanced accessibility of acid function sites.展开更多
Remote ether groups could be used as directing groups to prepare fully substituted 5-ether-1,2,3-triazoles with exclusive 1,5-regioselectivities and excellent chemoselectivities. Ether group could coordinate with irid...Remote ether groups could be used as directing groups to prepare fully substituted 5-ether-1,2,3-triazoles with exclusive 1,5-regioselectivities and excellent chemoselectivities. Ether group could coordinate with iridium catalyst by lone-pair electron at a distance(up to four σ bonds) away from alkyne to control the regioselectivity by weak coordination effect. The cycloaddition reaction chemoselectively occurred at the propargyl ether moiety of diyne to give unique fully substituted 4-alkynyl-triazole.展开更多
基金supported by the National Natural Science Foundation of China(21573232)~~
文摘The heterogeneity of active sites is the main obstacle for selectivity control in heterogeneous catalysis.Single atom catalysts（SACs） with homogeneous isolated active sites are highly desired in chemoselective transformations. In this work, a Pd1/ZnO catalyst with single‐atom dispersion of Pd active sites was achieved by decreasing the Pd loading and reducing the sample at a relatively low temperature. The Pd1/ZnO SAC exhibited excellent catalytic performance in the chemoselective hydrogenation of acetylene with comparable chemoselectivity to that of PdZn intermetallic catalysts and a greatly enhanced utilization of Pd metal. Such unusual behaviors of the Pd1/ZnO SAC in acetylene semi‐hydrogenation were ascribed to the high‐valent single Pd active sites, which could promote electrostatic interactions with acetylene but restrain undesired ethylene hydrogenation via the spatial restrictions of σ‐chemical bonding toward ethylene.
文摘The chemoselectivities of PdCl2 and CuCl2-catalyzed oligomerization of 3, 3-dimethyl-butyne: 1, 3, 5-tri-tert-butylbenzene, 2, 2, 7, 7-tetramethyl-3, 6-dichloro-3, 5-octadiene and 2, 2, 7, 7- tetramethyl-3, 5-octadiyne were obtained, respectively, by regulating the polarity of the solvent.
基金Scientific Research Project of General Universities in Guangdong Province(2023KTSCX036)Science and Technology Planning Program of Zhanjiang(2023B01015)for support.
文摘Ketenimine zwitterionic salt(KZS),a novel and stable ketenimine precursor,is still underexplored in the realm of chemical synthesis.In this study,we demonstrate the transformation of pyrrole derivatives through the cyclization of KZS withα-aminoketones.The diastereoselectivity of this reaction is influenced by the solvent,enabling the isolation of 3-hydroxypyrrolidine diastereomers with the highest reported dr value of 21:1.Furthermore,the chemoselectivity is modulated by the choice of base,yielding 2-aminopyrrole derivatives as the major products.This research offers a sustainable approach to harnessing the potential of KZS in organic synthesis,contributing to a greener chemical process.
基金the National Natural Science Foundation of China(Nos.22071149,21871178)the Natural Science Foundation of Shanghai(23ZR1428200)the Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learning for financial support.
文摘Lewis base catalyzed and Brønsted acid controlled chemodivergent electrophilic selenofunctionalizations of alkynes were developed for the first time.Various selenium-containing tetrasubstituted alkenes were readily obtained in moderate to excellent yields with complete E/Z selectivities.As the substrates were 1-ethynyl naphthol derivatives,linear selenium-containing tetrasubstituted alkenes were produced via intermolecular oxygen nucleophilic attack in the absence of acid additive;in contrast,cyclic selenium-containing tetrasubstituted alkenes were generated through intramolecular carbon nucleophilic capture with the addition of Brønsted acid.
基金supported by the National Natural Science Foundation of China(20372053,20672083 and 20872115)
文摘Solvent-free reactions of aromatic aldehydes with three representative ketones,including acetophenone,acetone and cyclohexanone,have been examined under the catalysis of a low-cost inorganic base system consisting of NaOH and K2CO3.It was found that the chemoselectivity of the reactions is in close relationship with the composition of the reactants and the doublecomponent catalyst.Under the optimized experimental conditions,1,2,3,4,5-pentasubstituted cyclohexanols,α,β-unsaturated ketones and Claisen-Schmidt bicondensation products were obtained in high yields.Two Kostanecki's triketones were separated,The composition and structure were affirmed by X-ray crystallographic analysis.
基金financial support from the National Natural Science Foundation of China(Nos.22074114,22377097,21877087)Natural Science Foundation of Hubei Province of China(Nos.2020CFB623,2021CFB556)+2 种基金Engineering Research Center of Phosphorus Resources Development and Utilization of Ministry of Education(No.LCX202305)Wuhan Institute of Technology Graduate Education and Teaching Reform Research Project(Nos.2022JYXM09,2021JYXM07)Wuhan Institute of Technology Graduate Innovation Fund(No.CX2022450)are greatly appreciated。
文摘A novel and readily available binaphthyl-based fluorescent probe(S)-1 was designed and synthesized.(S)-1 can be used to not only chemoselectively discriminate 3 basic amino acids out of common amino acids,but also enantioselectively recognize histidine.Encouragingly,enantioselective imaging of histidine in cells was achieved for the first time by the probe(S)-1.These performances endowed it potential application in the chiral analysis of basic amino acids in asymmetric synthesis and cell imaging for diagnosis of diseases caused by racemization of histidine.Nuclear magnetic resonance(NMR)and mass spectrometry investigations suggested that different reaction extent of(S)-1 with L/D-histidine and different product structures generated the observed enantioselective fluorescent response.The molecular structures and thermodynamic stability of the complexes,formed from(S)-1+Zn2+and enantiomers of histidine,were calculated by Gaussian 16 based on density functional theory(DFT)to validate the above action mechanism.
基金financially supported by the National Natural Science Foundation of China (Nos. 21972112 and 22225104)China Postdoctoral Science Foundation (Nos. 2022TQ0115 and 2022M711297)。
文摘Chemoselective,living/controlled polymerizations of allyl methacrylate(AMA) and vinyl methacrylate(VMA) with/without methyl methacrylate(MMA) by using the phosphonium ylide/organoaluminum based Lewis pairs(LPs) have been realized.The P-ylide-2/AIMe(BHT)_(2)(Pylide-2=Ph_(3)P=CHMe and BHT=2,6-iBu_(2)-4-MeC_(6)H_(2)O) was demonstrated to be superior by which homopolymers PAMAs(M_(n)=27.6-111.5kg/mol and ■=1.14-1.25) and PVMAs(M_(n)=28.4-78.4 kg/mol and ■=1.12-1.18) and block copolymers PMMA-b-PAMA,PAMA-b-PVMA,PAMA-bPMMA,PMMA-b-PAMA-b-PMMA,PAMA-b-PMMA-b-PAMA,and PAMA-b-PVMA-b-PAMA were synthesized.In the polymerizations,all of the monomers were reacted by the conjugated ester vinyl groups leaving intactly the nonconjugated acryloxy groups.The pendant acryloxy groups attached to the main chain enable further to post-functionalization by the AIBN-induced radical "thiol-ene" reaction using PhCH_(2)SH.The thiolether side group-containing polymers PAMA-SCH_(2)Ph and PAMA-SCH_(2)Ph-b-PMMA-b-PAMA-SCH_(2)Ph were thus prepared.
基金the support from the National Natural Science Foundation of China (Nos.21974067, 22274073, 81971373 and 82001535)the National Key Research and Development Program of China (No.2018YFC1004700)+1 种基金Fundamental Research Funds for the Central Universities (Nos.020514380309,021414380502 and 2022300324)the State Key Laboratory of Analytical Chemistry for Life Science (Nos.5431ZZXM2305 and 5431ZZXM2204)。
文摘Spermatogenesis, maturation, capacitation and fertilization are precisely regulated by glycosylation. However, the relationship between altered glycosylation patterns and the onset and development of reproductive disorders is unclear, mainly limited by the lack of in situ imaging techniques for spermatozoa glycosylation. We developed an efficient and highly specific spermatozoa glycan imaging technique based on the robust chemoselective labeling of sialic acid(Sia) and N-acetyl-D-galactosamine(Gal/GalNAc). We further proposed a “tandem glycan chemoselective labeling” strategy to achieve simultaneous imaging of two types of glycans on spermatozoa. We applied the developed method to the spermatozoa from oligozoospermic patients and diabetic mice and found that these spermatozoa showed higher levels of Sia and Gal/Gal NAc expression than the normal groups. Moreover, spermatozoa from diabetic mice showed a severe decrease in number, viability, and forward motility, suggesting that in vivo glucose metabolism disorders may lead to an elevated level of spermatozoa glycosylation and have a correlation with the development of oligoasthenotspermia. Our work provides a research tool to reveal the relationship between glycosylation modification and spermatozoa quality, and a promising clue for the development of glycan-based reproductive markers.
基金supported by the National Key R&D Programs(No.2021YFA0910001)the Shenzhen Science and Technology Program(Nos.JCYJ20210324115804013,JCYJ2022081810160716,JCYJ20220531093604009)+2 种基金the Specific Research Assistant Funding Program of Chinese Academy of Sciences(No.E35902)the National Natural Science Foundation of China(Nos.22005343,32000982)the Guangdong Provincial Key Area R&D Program(No.2020B1111540001).
文摘Carbon monoxide(CO)is a vital intracellular gas messenger known for its cytoprotective and homeostatic properties.It plays a pivotal role in a myriad of biological processes.Therefore,the precise detection of CO is of paramount importance in unraveling the intricacies of pathological mechanisms and advancing the development of disease diagnosis.We herein introduce NFCOP,a state-of-the-art near-infrared(NIR)turn-on fluorescence(FL)probe that has been meticulously designed for highly sensitive,swift and selective imaging of CO.The NFCOP response occurred rapidly with CO,within just 10 s,and the calculated detection limit for CO was determined to be 0.32μmol/L.Further investigations conducted at the cellular level and in vivo demonstrated that NFCOP possesses high sensitivity and selectivity for imaging CO.
基金Fundamental Research Program of Shanxi Province of China(No.20210302123037)Research Project Supported by Shanxi Scholarship Council of China(No.2022-136)Specialized Research Fund for Sanjin Scholars Program of Shanxi Province of China.
文摘The chemoselective hydrogenation of structurally diverse nitroaromatics is a challenging process.Generally,catalyst activity tends to decrease when excellent selectivity is guaranteed.We here present a novel photocatalyst combining amino-functionalized carbon dots(N-CDs)with copper selenite nanoparticles(N-CDs@CuSeO_(3))for simultaneously improving selectivity and activity.Under visible light irradiation,the prepared N-CDs@CuSeO_(3)exhibits 100%catalytic selectivity for the formation of 4-aminostyrene at full conversion of 4-nitrostyrene in aqueous solvent within a few minutes.Such excellent photocatalytic performance is mainly attributed to the precise control of the hydrogen species released from the ammonia borane by means of light-converted electrons upon N-CDs@CuSeO_(3).Besides,the defect states at the interface of N-CDs and CuSeO_(3)enable holes to be trapped for promoting separation and transfer of photogenerated charges,allowing more hydrogen species to participate in catalytic reaction.
基金supported by the National Natural Science Foundation of China(21322606,21436005,21576095)China Postdoctoral Science Foundation(2016M590771)Guangdong Natural Science Foundation(2016A030310413,2013B090500027,2014A030310445,2016A050502004)~~
文摘Metal-organic-framework （MOF）-based materials with novel physicochemical properties have emerged as promising catalysts for various hydrogenation reactions. In addition to metal clusters and multifunctional organic ligands, MOF-based catalysts can incorporate other functional species, and thus provide various active sites for hydrogenation processes. The structural properties of the catalysts play significant roles in enhancing the interactions among the reactants, products, and catalytic sites, which can be rationally designed. Because of the synergistic effects between the ac-tive sites and the structural properties, MOF-based catalysts can achieve higher activities and selec- tivities in hydrogenation reactions than can be obtained using traditional heterogeneous catalysts. This review provides an overview of recent developments in MOF-based catalysts in the hydro-genation of alkenes, alkynes, nitroarenes, cinnamaldehyde, furfural, benzene, and other compounds. Strategies for improving the catalytic performances of MOF-based catalysts are discussed as well as the different active sites and structural properties of the catalysts.
基金supported by the National Natural Science Foundation of China(21473073,21473074)‘‘13th Five-Year’’ Science and Technology Research of the Education Department of Jilin Province(2016403)+1 种基金the Development Project of Science and Technology of Jilin Province(20170101171JC,20180201068SF)the Open Project of State Key Laboratory of Inorganic Synthesis and Preparative Chemistry(201703)~~
文摘An efficient and low-cost supported Pt catalyst for hydrogenation of niroarenes was prepared with colloid Pt precursors andα-Fe2O3 as a support.The catalyst with Pt content as low as 0.2 wt%exhibits high activities,chemoselectivities and stability in the hydrogenation of nitrobenzene and a variety of niroarenes.The conversion of nitrobenzene can reach 3170 molconv h^–1 molPt^–1 under mild conditions(30°C,5 bar),which is much higher than that of commercial Pt/C catalyst and many reported catalysts under similar reaction conditions.The spatial separation of the active sites for H2 dissociation and hydrogenation should be responsible for the high chemoselectivity,which decreases the contact possibility between the reducible groups of nitroarenes and Pt nanoparticles.The unique surface properties ofα-Fe2O3 play an important role in the reaction process.It provides active sites for hydrogen spillover and reactant adsorption,and ultimately completes the hydrogenation of the nitro group on the catalyst surface.
文摘Ferrous methanesulfonate catalysing the conversion of aromatic, heteroaromatic, unsaturated, and aliphatic aldehydes to 1,1- diacetates at room temperature under solvent-free condition has been developed. The catalytic activity of seventeen metal methanesulfonates was compared under the same condition, ferrous methanesufonate proved to be the best. It can be easily recovered and reused for several times without distinct deterioration in catalytic activity. During the competitive protection between a ketone and an aldehyde group with Ac20, 1,1-diacetate formed exclusively with the aldehyde group. 2009 Min Wang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
基金Supported by the National Key Project of Scientific and Technical Supporting Programs Funded by Ministry of Science & Technology of China (2006BAE03B06)Shanghai Leading Academic Discipline Project (B409)Shanghai International Cooperation of Science and Technology Project (06SR07101)
文摘The novel efficient procedure has been developed for the conjugate addition of amines to electron deficient alkenes.A series of hydrotalcite-like materials were synthesized as catalyst for the conjugate addition of amines and alkenes.After optimizing the reaction conditions,ZnAl-LDHs (3:1) was chosen as the best catalyst for the reaction.The results showed that the catalyst worked very well for the conjugate addition of amines to electron deficient alkenes with the excellent yields in several minutes.Operational simplicity,no solvent,low cost of the catalyst,high yields,reusability,excellent chemoselectivity,wide applicability are the key features of this method.
基金the Higher Committee for Education Development in Iraq for financial support(AHB)the Commonwealth Scholarships Commission in the UK for a Split-Site PhD Scholarship(RB)
文摘Methanol is a safe, economic and easy-to-handle hydrogen source. It has rarely been used in transfer hydrogenation reactions, however. We herein report that a cyclometalated rhodium complex, rhodacycle, catalyzes highly chemoselective hydrogenation of α,β-unsaturated ketones with methanol as the hydrogen source. A wide variety of chalcones, styryl methyl ketones and vinyl methyl ketones, including sterically demanding ones, were reduced to the saturated ketones in refluxing methanol in a short reaction time, with no need for inter gas protection, and no reduction of the carbonyl moieties was observed. The catalysis described provides a practically easy and operationally safe method for the reduction of olefinic bonds in α,β-unsaturated ketone compounds.
基金Supported by the National Natural Science Foundation of China(No.20676020)the Program for Changjiang Scholars and Innovative Research Team in Universities of China(No.IRT0711).
文摘A convenient, environmentally benign, and highly efficient protocol for the preparation of N-arylhydroxylamines from the corresponding nitroarenes in a Zn/HCOONH4/CH3CN system under ultrasound is described The advantages of the present method include high chemoselectivity, simple and practical work-up procedure and high yield.
基金financial support from the National Natural Science Foundation of China(No.21602144)the Science and Technology Program of Sichuan Province(No.2018JY0485)Scientific Research Project of Education Department of Hubei Province(Nos.Q20211503,B2020057)。
文摘The utilization of readily available amino acids,which is not only an oxygen nucleophile but also a nitrogen nucleophile,in palladium-catalyzed allylic substitution is realized under mild conditions.The chemoselectivity and multiple allylation are controlled by adjusting the reaction conditions.This represents the first example of this convenient access to valuable N,O-diallylated amino acids.Under the title conditions,a range of amino acids(α-,β-,γ-)and dipeptides can be readily converted in to the corresponding allylic products with excellent yields(67 examples,up to 99%yield)as well as good functional group tolerance.
基金Financial support from the National Natural Science Foundation of China (Nos. 21901041 and 21772023)State Key Laboratory of Physical Chemistry of Solid Surfaces,Xiamen University (No.202008)Fuzhou University (No. 510841)。
文摘Both sulfur and fluorine play important roles in organic synthesis, the life science, and materials science.The direct incorporation of these elements into organic scaffolds with precise control of the oxidation states of sulfur moieties is of great significance. Herein, we report the highly selective electrochemical vicinal fluorosulfenylation and fluorosulfoxidation reactions of alkenes, which were enabled by the unique ability of electrochemistry to dial in the potentials on demand. Preliminary mechanistic investigations revealed that the fluorosulfenylation reaction proceeded through a radical-polar crossover mechanism involving a key episulfonium ion intermediate. Subsequent electrochemical oxidation of fluorosulfides to fluorosulfoxides were readily achieved under a higher applied potential with the adventitious H;O in the reaction mixture.
文摘The catalytic hydrogenation of halonitroarenes to haloanilines is a green and sustainable process for the production of key nitrogen-containing intermediates in fine chemical industry.Chemoselective hydrogenation poses a significant challenge,which requires the rational design of the catalysts with proper hydrogenation ability for nitro group and simultaneously preventing dehalogenation of halogen group.Herein,a highly effective Rh@Al_(2)O_(3)@C single-atom catalyst(SAC)was developed for the hydrogenation of m-chloronitrobenzene(m-CNB)to m-chloroaniline(m-CAN),through an in-situ grafting of metal during the assembly of MIL-53(Al),followed by confined pyrolysis.Extensive characterizations reveal an exquisite structure of the Rh@Al_(2)O_(3)@C,containing atomically dispersed Rh sites onto Al_(2)O_(3) confined by the amorphous carbon.The five-coordinated aluminum(Al^(Ⅴ))species are essential for achieving the atomic dispersion of Rh atoms,providing the unsaturated coordinative sites for metal.Compared to the benchmark Rh/γ-Al_(2)O_(3) and Rh/C nanocatalysts,the Rh@Al_(2)O_(3)@C SAC affords an excellent turnover frequency of 2317 molm-CNB·molRh^(–1)·h^(–1),the highest value to date in heterogeneous catalyst systems for the hydrogenation of m-CNB at 313 K and 20 bar H2,together with a sustained selectivity to m-CAN(~98%)during five consecutive runs.The superior catalytic performance of the Rh@Al_(2)O_(3)@C is attributed to a proper modulation of electronic structure of hydrogenation metal by forming SAC,together with an enhanced accessibility of acid function sites.
基金supported by grants from the National Natural Science Foundation of China (No. 21978039)Special Funds of the Central Government Leading Local Government for the Technology Development (Nos. 2021JH6/10500146, 2021JH6/10500148)the Fundamental Research Funds for the Central Universities (Nos. DUT20YG120, DUT19LK60)。
文摘Remote ether groups could be used as directing groups to prepare fully substituted 5-ether-1,2,3-triazoles with exclusive 1,5-regioselectivities and excellent chemoselectivities. Ether group could coordinate with iridium catalyst by lone-pair electron at a distance(up to four σ bonds) away from alkyne to control the regioselectivity by weak coordination effect. The cycloaddition reaction chemoselectively occurred at the propargyl ether moiety of diyne to give unique fully substituted 4-alkynyl-triazole.
