查看更多>>摘要：Stereoselective synthesis of multi-substituted cyclobutanes with different substituents is still a daunting challenge in organic synthe-sis.We report here a practical and facile approach to synthesizing all-trans 2,3,4-trisubstituted cyclobutanones from readily available dichlorocyclobutanones.The substitution reaction proceeds smoothly via oxyallyl cation intermediates under mild basic conditions.Further transformation to the synthesis of 1,2,3,4-tetrasubstituted cyclobutanes was also explored.
查看更多>>摘要：Palladium-catalyzed regioselective amination of unactivated alkene remains a challenge and is of great interest.Herein,a three-component coupling of unactivated alkene,sulfonamide,and N-halo compounds accessing vicinal haloamine has been con-ceived.This aminohalogenation represents a modular and regioselective strategy.The electrophilic halogenating agent enables regi-oselective anti-Markovnikov aminopalladation and facilitates subsequent halogenation events.And this protocol is characterized by gram-scale syntheses and late-stage functionalizations.Of note,the recovered byproduct phthalimide allows for reusing by conver-sion to the starting material.
查看更多>>摘要：The electrophilic addition to an alkene with an electrophile has been widely studied and applied in organic synthesis.The organic chemistry textbook describes the classical reaction between an alkene and an iodine electrophile(such as elemental iodine and N-iodosuccinimide(NIS))as a typical ionic reaction,in which an iodonium ion is formed and then attacked by a nucleophile.However,in this article,we report a new and unusual reaction mode between an alkene and NIS;that is,a single electron transfer(SET)process occurs between these two reactants by forming an electron-donor acceptor complex.Not only does this unusual single electron transfer reaction between an alkene and NIS add fundamentally important knowledge to organic chemistry,it also provides a valuable synthetic method as the new SET reaction mode with opposite regioselectivity as compared with the traditional ionic mode.
查看更多>>摘要：Large-area AgNWs electrodes(25 cm × 10 cm)were fabricated through roll-to-roll printing on the polyvinyl alcohol(PVA)modified water and oxygen barrier substrate.The modification of the barrier film with PVA improved the wettability of silver nanowires on the barrier films and led to the formation of homogenous large-area AgNWs networks.The mechanical flexibility,especially the adhesion force between the silver electrode and the barrier film substrate was dramatically improved through PVA modification.The efficien-cy of 13.51％for the flexible OSCs with an area of 0.64 cm2 was achieved based on the PET/barrier film/PVA/AgNWs electrode.The long-term stability showed the flexible OSCs based on the PET/barrier film/PVA/AgNWs electrode have a significantly improved sta-bility relative to the device on PET/AgNWs electrode,and comparable air stability as the rigid device with glass/ITO device.The un-encapsulated devices maintained nearly 50％of the original efficiency after storage for 600 h in air.After a simple top encapsulation,the flexible devices remained at 60％of the initial efficiency after 2000 h in the air.Therefore,the flexible AgNWs electrode based on the barrier film would have the potential to improve the air storage stability of organic flexible solar cells.
查看更多>>摘要：By employing the asymmetric end-group engineering,an asymmetric nonfused-ring electron acceptor(NFREA)was designed and syn-thesized.Compared with the symmetric analogs(NoCA-17 and NoCA-18),NoCA-19 possesses broader light absorption range,more coplanar π-conjugated backbone,and appropriate crystallinity according to the experimental and theoretical results.The organic solar cells based on J52∶NoCA-19 exhibited a power conversion efficiency as high as 12.26％,which is much higher than those of J52∶NoCA-17(9.50％)and J52∶NoCA-18(11.77％),mainly due to more efficient exciton dissociation,better and balanced charge mobil-ity,suppressed recombination loss,shorter charge extraction time,longer charge carrier lifetimes,and more favorable blend film morphology.These findings demonstrate the great potential of asymmetric end-group engineering in exploring low-cost and high-performance NFREAs.
查看更多>>摘要：Monitoring of sweat pH plays important roles in physiological health,nutritional balance,psychological stress,and sports perfor-mance.However,the combination of functional MOFs with phosphorescent material to acquire the real-time physiological informa-tion,as well as the application of dual mode anti-counterfeiting,has seldom been reported.Herein,we developed multifunctional gel films based on MOFs and phosphorescent dyes which responded to H+ions and the related mechanism was studied in detail.Upon exposure to H+,the composite gel film exhibited decreased fluorescent signal but enhanced room temperature phosphorescence(RTP),which could be utilized for sweat pH sensing through a dual-mode.Moreover,multifunctional gel films exhibited a potential ap-plication in information encryption and anti-counterfeiting by designing of stimulus responsive multiple patterns.This research pro-vided a new avenue for portable and non-invasive sweat pH monitoring methods while also offering insights into stimulus-responsive multifunctional materials.
查看更多>>摘要：N6-methyladenosine(m6A)plays an important role in embryogenesis,nuclear export,transcription splicing,and protein translation control.Herein,we demonstrate a copper-free click chemistry-mediated assembly of single quantum dot(QD)nanosensor for accu-rately monitoring locus-specific m6A in cancer cells.The m6A-sensitive endoribonuclease MazF can digest the unmethylated A-RNA,and the intact m6A-RNA then hybridizes with DNA probes a and b to produce a sandwich hybrid,initiating the click chemistry to gen-erate probe a-b ligation product via first tandem ligation detection reaction(LDR)cycle.Subsequently,DNA probes c and d can hy-bridize with the probe a-b ligation product to generate the probe c-d ligation product via second LDR cycle.Both LDR cycles can be repeated through denaturation and annealing reaction to generate abundant biotin-/fluorophore-modified probe c-d ligation prod-ucts that can easily assemble on the QD surface to induce distinct fluorescence resonance energy transfer(FRET)between QD and Cy5.This assay can be homogenously performed without the involvement of copper catalyst,m6A-specific antibody,radioactive la-beling,ligase enzyme,enzymatic reverse transcription,and next-generation sequencing.Moreover,it can discriminate even 0.01％m6A level in complex samples and accurately measure cellular mA-RNA expression,providing a promising avenue for clinical diag-nostics and biomedical research.
查看更多>>摘要：A metal-free,green,and sustainable functionalization of unactivated alkyl sp3 C—H bonds is reported using iodine(Ⅲ)as a feasible dehydrogenation agent under visible light or KBr,and alkyl chlorides,bromides,alcohols,and ketones could be constructed by addi-tion of different coupling reagents.Cheap and safe iodobenzene diacetate was used to form a radical to activate the alkyl sp3 C—H bond in a highly efficient manner,which can construct different alkylation products by adding corresponding coupling reagents.
查看更多>>摘要：Cooperative NHC/photoredox catalysis has emerged as an important research field in recent years.Herein,this article describes the use of cesium salt derivatives of tert-alcohols as alkyl radical precursors in a three-component reaction with styrene and aromatic acyl fluorides to synthesize α-arylalkyl aryl ketones.The aroyl fluoride reacts with the NHC catalyst,leading to the formation of an acyl az-olium ion.This acyl azolium ion can then be reduced by the photoredox catalyst,generating the corresponding ketyl radical anion.The C-radical generated from oxalate oxidation undergoes an addition reaction with the styrene derivative,followed by cross-coupling of the addition radical with the ketone radical,which is fragmented by NHC to give the target ketone.
查看更多>>摘要：Traditional carbon fiber-reinforced polymers based on thermoset matrix have been extensively used in the fields of wind turbine blades,automotive sector,and aerospace,among many others.However,there is still a major challenge of recycling those polymers due to the high cost and adverse impacts on the environment.In this work,we apply a polyimine network as matrix,which possess considerable tensile and thermal properties,to prepare the carbon fiber reinforced polyimine materials with trifluoromethyl diphe-noxybenzene units(CFRFP)using a prepreg-based compression molding method.The CFRFP can be reshaped or reprocessed by heat or with water rapidly,and exhibited multifunction,including welding,chemical recycling,etc.These unique findings gained from our study will facilitate the manufacturing capability and enrich the types of fiber-reinforced composites.
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