A novel method for synthesis of quinazoline through the hydrogen transfer/annulation reaction using 2-nitrobenzyl alcohol and benzylamine as starting materials is presented.The reaction is catalyzed by a ruthenium(II)...A novel method for synthesis of quinazoline through the hydrogen transfer/annulation reaction using 2-nitrobenzyl alcohol and benzylamine as starting materials is presented.The reaction is catalyzed by a ruthenium(II)complex bearing a N-heterocyclic carbene nitrogen phosphine(CNP)ligand.The pronouncedα-donating capacity of the carbene within the CNP ligand of the catalyst plays a crucial role in stabilizing the catalytically active species.Additionally,the hemilability of the nitrogen facilitates the creation of coordination vacancies,which are essential for the activation of reaction substrate molecules.The synergistic interplay between these two functionalities markedly enhances catalytic efficiency.This catalytic system shows the significant catalytic activity and selectivity,along with a broad substrate adaptability.All substrates yield the target product in good to excellent yields with the maximum yield reaching 95%.Control experiments have substantiated that benzaldehyde and phenylmethanimine may serve as intermediates in the reaction,thereby reinforcing the role of benzylamine as both a hydrogen donor and a nitrogen source in the process.展开更多
Peptides play important roles in chemistry,medicinal chemistry and life science,due to their high efficiency and specificity,unusual biological and therapeutic properties.As naturally occurring peptides often face wit...Peptides play important roles in chemistry,medicinal chemistry and life science,due to their high efficiency and specificity,unusual biological and therapeutic properties.As naturally occurring peptides often face with their intrinsic limitations including metabolic instability and low membrane permeability,the strategies for synthesizing unnatural amino acids and peptides are explored.Among the methods for modifying amino acids and peptides,chemo-and site-selective approaches are preferred because of the ability to fine-tuning structural features.Recently,transition metal-catalyzed Csingle bondH activation has been employed for the functionalization of amino acids and peptides.Through domino Csingle bondH activation/annulation,a series of structurally complex and diverse amino acids and peptides is constructed.This review highlights recent advances in the synthesis of unnatural amino acids and peptides via transition metal-catalyzed Csingle bondH activation/annulation.展开更多
An efficient strategy for construction of tricyclic thiazino[3,4-a]isoquinolines has been achieved via 4-dimethylamino-pyridine(DMAP)promoted[5+1]annulation of simple and readily available isoquinoline 1,4-zwitterion ...An efficient strategy for construction of tricyclic thiazino[3,4-a]isoquinolines has been achieved via 4-dimethylamino-pyridine(DMAP)promoted[5+1]annulation of simple and readily available isoquinoline 1,4-zwitterion withα-bromoketone.This protocol showed good substrate compatibility as an array of structurally and electronically diverse thiazino[3,4-a]isoquinolines prepared efficiently in moderate to good yields.It is particularly emphasized that although this reaction exhibits moderate stereoselectivity,the two diastereomers can be separated by column chromatography,providing an important molecular diversity foundation for the screening and structural optimization of subsequent drug lead compounds,as well as a simple and efficient method for constructing complex nitrogen-containing and sulfur-containing heterocyclic compounds.It has potential application value in the fields of medicinal chemistry and organic synthesis.展开更多
A[3+4]annulation of α-substituted allenes and Schiff bases is reported.This methodology serves as a conduit for the construction of a series of biologically important benzazepine derivatives in good to excellent yiel...A[3+4]annulation of α-substituted allenes and Schiff bases is reported.This methodology serves as a conduit for the construction of a series of biologically important benzazepine derivatives in good to excellent yields under mild conditions by an unprecedented mode involving β’-carbon of α-substituted allenes and the proposed mechanism is supported by capturing the intermediate.Moreover,this class of benzazepine derivatives exhibited potential ability of cytotoxicity toward cancer cells.展开更多
Designing efficient,recyclable,and low-cost catalysts is crucial for the synthesis of quinoxaline derivatives.In this context,a novel N-stable Co_(2)P nano-catalyst(CoP@N–C-1.5)was developed using a templatesacrifici...Designing efficient,recyclable,and low-cost catalysts is crucial for the synthesis of quinoxaline derivatives.In this context,a novel N-stable Co_(2)P nano-catalyst(CoP@N–C-1.5)was developed using a templatesacrificial approach.The catalyst demonstrated a broad substrate scope and good functional group tolerance,achieving yields of up to 84%.Additionally,the catalyst exhibited reusability and can be recycled up to three times.The CoP@N–C-1.5 was characterized using X-ray powder diffraction(XRD),scanning electron microscopy(SEM),and transmission electron microscopy(TEM).The results indicated that the catalyst contained Co2P nanoparticles.The X-ray photoelectron spectroscopy(XPS)further confirms the presence of Co-P.Analysis of the characterization data and experimental results revealed that the active site of the catalyst comprises N-stable Co_(2)P nanoparticles.展开更多
Chromones serve as versatile heterocyclic scaffolds and are common core structural units in a variety of natural products and bioactive organic molecules.This area of research,at the forefront of organic synthesis,has...Chromones serve as versatile heterocyclic scaffolds and are common core structural units in a variety of natural products and bioactive organic molecules.This area of research,at the forefront of organic synthesis,has seen remarkable progress in recent years.Among the various synthetic methodologies for accessing chromone scaffolds,the tandem annulation of o-hydroxyaryl enaminones has emerged as a robust and practical strategy.This approach,through direct vinyl C-H bond functionalization of o-hydroxyaryl enaminones,enables the construction of structurally diverse chromones(including 3-substituted chromones,2-substituted chromones,and 2,3-disubstituted chromones)and their derivatives since mid-2019.In this review,we highlight recent advances in the synthesis of various types of chromones and their derivatives,achieved through tandem direct vinyl C-H activation and chromone annulation of o-hydroxyaryl enaminones.展开更多
Polycyclic compounds are widely found in natural products and drug molecules with important biological activities,which attracted the attention of many chemists.Phosphine-catalyzed nucleophilic addition is one of the ...Polycyclic compounds are widely found in natural products and drug molecules with important biological activities,which attracted the attention of many chemists.Phosphine-catalyzed nucleophilic addition is one of the most powerful tools for the construction of various cyclic compounds with the advantages of atom economy,mild reaction conditions and simplicity of operation.Allenolates,Morita−Baylis−Hillman(MBH)alcohols and their derivatives(MBHADs),electron-deficient olefins and alkynes are very efficient substrates in phosphine mediated annulations,which formed many phosphonium species such asβ-phosphonium enolates,β-phosphonium dienolates and vinyl phosphonium ylides as intermediates.This review describes the reactivities of these phosphonium zwitterions and summarizes the synthesis of polycycle compounds through phosphine-mediated intramolecular and intermolecular sequential annulations.Thus,a systematic summary of the research process based on the phosphine-mediated sequential annulations of allenolates,MBH alcohols and MBHADs,electron-deficient olefins and alkynes are presented in Chapters 2-6,respectively.展开更多
A new oxidative N-heterocyclic carbene(NHC)-catalyzed high-order[7+3]annulation reaction ofγ-indolyl phenols as 1,7-dinucleophiles andα,β-alkynals with the aid of Sc(OTf)_(3)is reported,enabling the highly regiosel...A new oxidative N-heterocyclic carbene(NHC)-catalyzed high-order[7+3]annulation reaction ofγ-indolyl phenols as 1,7-dinucleophiles andα,β-alkynals with the aid of Sc(OTf)_(3)is reported,enabling the highly regioselective access to unprecedented polyarene-fused ten-membered lactams bearing a bridged aryl-aryl-indole scaffold in moderate to good yields.This protocol demonstrates a broad substrate scope,good compatibility with substituents and complete regioselectivity,providing an organocatalytic modular synthetic strategy for creating medium-sized lactams.展开更多
Fluorescent probes based on intramolecular charge transfer(ICT) have obvious advantages for accurate quantitative analysis.To obtain high-performance ratiometric probes requires distinct photophysical properties durin...Fluorescent probes based on intramolecular charge transfer(ICT) have obvious advantages for accurate quantitative analysis.To obtain high-performance ratiometric probes requires distinct photophysical properties during recognition reaction process,which is closely related to their ICT characteristics.1,8-Naphthalimide is known as a typical fluorophore with desirable ICT property when functionalized with an electron-donating moiety at the para-position of the naphthalene chromophore.Although the photophysical properties of para-substituted 1,8-naphthalimide have been well studied,its meta-substituted counterpart has not been fully evaluated since the meta-position is conventionally thought to be weakly conjugated.Herein,combined experimental and theoretical studies are performed which consistently indicate that stronger charge transfer(CT) is exhibited by the meta-amino substituted 1,8-naphthalimide(m-NH_(2)) compared to the para-amino substituted one(p-NH_(2)).The ratiometric response of fluorescence with significant changes in wavelength and intensity upon acetylation(m-NAc and p-NAc) can be attributed to the larger ICT and stronger-NH_(2) vibrations.This observation is further demonstrated by deuterium oxide experiments,viscosity experiments and quantum chemical calculations.The practical application of meta-amino-1,8-naphthalimide ICT-based probes is also confirmed.This research is expected to bring an in-depth understanding of π-conjugated systems with ICT characteristics,and facilitates the design of sensitive ICT fluorescent probes with meta-amino substitution.展开更多
Combining the advantages of high efficiency,low-pressure drop,and large throughput,the pore arrayenhanced tube-in-tube microchannel(PA-TMC) is a promising microreactor for industrial applications.However,most of the m...Combining the advantages of high efficiency,low-pressure drop,and large throughput,the pore arrayenhanced tube-in-tube microchannel(PA-TMC) is a promising microreactor for industrial applications.However,most of the mass transfer takes place in the upstream pore region,while the contribution of the downstream annulus is limited.In this work,helical wires were introduced into the annulus by adhering to the outer surface of the inner tube.Mixing behavior and mass transfer of liquid-liquid twophase flow in PA-TMC with different helical wires have been systematically studied by a combination of experiments and volume of fluid(VOF) method.The introduction of helical wires improves the overall volumetric mass transfer coefficient KLa by up to 133% and the mass transfer efficiency E by up to 117%.The simulation results show that the helical wire brings extra phase mixing regions and increases the specific interface area,while accelerating the fluid flow and expanding the area of enhanced turbulent dissipation rate.Influences of helical wires in various configurations are compared by the comprehensive index I concerning the pressure drop and mass transfer performance simultaneously and a new correlation between KLa and specific energy consumption φ is proposed.This research deepens the understanding of the mixing behavior and mass transfer in the PA-TMCs and provides practical experience for the process intensification of microchannel reactors.展开更多
Catalytic C–H activation-initiated annulation reactions have emerged as a versatile strategy for the efficient construction of diverse ring structural units and complex cyclic molecules in synthetic chemistry.Herein,...Catalytic C–H activation-initiated annulation reactions have emerged as a versatile strategy for the efficient construction of diverse ring structural units and complex cyclic molecules in synthetic chemistry.Herein,we describe a new Rh(Ⅲ)-catalyzed C–H activation-initiated transdiannulation reaction of N,Ndimethyl enaminones with gem-difluorocyclopropenes in the presence of H_(2)O,enabling a facile and oxygen transfer access to ring-fluorinated tricyclicγ-lactones with a 6-5 ring-junction tetrasubstituted stereocenter.This approach features bond-forming/annulation efficiency,good functional group tolerance and complete regioselectivity,which may include a complex process consisting of Rh(Ⅲ)-catalyzed C(sp2)–H activation,cyclic alkene insertion,defluorinated ring-opening of gem-difluorocyclopropane,intramolecular oxygen transfer,intramolecular cyclization and oxidative hydration.展开更多
A visible-light-induced synergistic hydrogen atom transfer(HAT)and proton transfer(PT)catalysis was developed for the defluorinative carboxylation of α-CF_(2)R-substituted alkenes.This system affords a variety of γ,...A visible-light-induced synergistic hydrogen atom transfer(HAT)and proton transfer(PT)catalysis was developed for the defluorinative carboxylation of α-CF_(2)R-substituted alkenes.This system affords a variety of γ,γ-difluoro-and γ-monofluoro-vinylacetic acids without stepwise acidification,exhibiting good functional group tolerance,broad scope,and facile scalability.Mechanism studies support that thiol plays the role of the hydrogen relay,which s a hydrogen atom through HAT and then outputs a proton via PT.This strategy also takes full advantage of formate for photocatalytic carboxylation reaction in a step-and atomeconomical way.展开更多
This study investigates the enhancement of convective heat transfer in a serpentine pipe using ferrofluid flow influenced by dual non-uniform magnetic sources.The primary objective is to improve thermal performance in...This study investigates the enhancement of convective heat transfer in a serpentine pipe using ferrofluid flow influenced by dual non-uniform magnetic sources.The primary objective is to improve thermal performance in compact cooling systems,such as those used in heat exchangers.A two-dimensional,steady-state Computational Fluid Dynamic(CFD)model is developed in ANSYS Fluent to simulate the behavior of an incompressible ferrofluid under applied constant heat flux and magnetic fields.The magnetic force is modeled using the Kelvin force,which acts on magnetized nanoparticles in response to spatially varying electromagnetic fields generated by two strategically positioned current-carrying wires.The effects of magnetic field strength,quantified by the magnetic number(Mn),on flow behavior and temperature distribution are thoroughly analyzed.The results indicate that increasing Mn leads to higher Nusselt numbers,demonstrating enhanced convective heat transfer.Secondary vortices induced by magnetic forcing improve fluid mixing,particularly in curved regions of the pipe.A mesh-independence study and model validation with benchmark data support the reliability of the numerical framework.This work highlights the potential of magnetic-field-assisted thermal control in energy-efficient cooling applications and provides a foundation for the further development of advanced ferrofluid-based heat transfer systems.展开更多
Accurate assessment of seismic landslide susceptibility is crucial for disaster prevention and emergency decision-making.Although machine learning methods have been widely applied in this field,they exhibit a strong d...Accurate assessment of seismic landslide susceptibility is crucial for disaster prevention and emergency decision-making.Although machine learning methods have been widely applied in this field,they exhibit a strong dependence on large quantities of highquality samples,resulting in significantly low prediction accuracy of existing studies under data-scarce or crossregional prediction scenarios,which fail to meet practical application requirements.To address this issue,this study proposes an intelligent prediction model integrating transfer learning and a sampling optimization strategy,aiming to enhance the accuracy and applicability of seismic landslide susceptibility assessment.The model first improves the sample collection method through the sampling optimization strategy to enhance the precision and representativeness of training samples.This not only ensures the accuracy of origin area training but also further strengthens the model's predictive ability in the target area.Subsequently,it incorporates Transfer Component Analysis(TCA)to overcome the differences in environmental characteristics between the origin area and target area,and couples TCA with the Light GBM algorithm to construct the TCA-Light GBM model,realizing the assessment of seismic landslide susceptibility in sample-free areas.Validated through case studies of the Jiuzhaigou and Luding earthquakes,the results demonstrate that the proposed TCALight GBM transfer learning method exhibits excellent applicability in seismic landslide susceptibility prediction.After optimization with the TCA algorithm,the model's prediction performance in the target domain is significantly improved,with the AUC value increasing from 0.719 to 0.827,representing an increase of approximately 15.02%.This indicates that TCA technology can effectively alleviate the feature distribution discrepancy between the source domain and target domain,enhancing the model's generalization ability.The method is particularly suitable for scenarios with data scarcity and cross-regional prediction and can provide reliable technical support for the emergency response and risk prevention and control of seismic hazards.展开更多
The development of catalytic multicomponent reactions for constructing complex organic scaffolds from readily accessible commodity chemicals is a key pursuit in contemporary synthetic chemistry.Current methods for syn...The development of catalytic multicomponent reactions for constructing complex organic scaffolds from readily accessible commodity chemicals is a key pursuit in contemporary synthetic chemistry.Current methods for synthesizing thioesters primarily rely on the acylation of thiols,which produces substantial waste and requires malodorous,unstable sulfur sources.In this work,we introduce a photocatalyzed hydrogen transfer strategy that enables a three-component synthesis of thioesters using abundant primary alcohols,easily available alkenes and elemental sulfur under mild conditions.This protocol demonstrates broad applicability and high chemo-and regioselectivity for both primary alcohols and alkenes,highlighting the advantage and potential of photo-mediated hydrogen transfer in facilitating multicomponent reactions using primary alcohol and elemental sulfur feedstocks.展开更多
The severe shuttle effect and sluggish reaction kinetics in room-temperature sodium-sulfur(RT Na-S)batteries have been major bottlenecks hindering their practical application.To overcome these challenges,a straightfor...The severe shuttle effect and sluggish reaction kinetics in room-temperature sodium-sulfur(RT Na-S)batteries have been major bottlenecks hindering their practical application.To overcome these challenges,a straightforward reduction approach was employed to design three bimetallic alloy nanoparticles(FeNi,FeCo,and NiCo)supported on multistage porous carbon substrates.Experimental and theoretical calculations reveal that the charge transfer within the alloy catalyst influences the position of its d-band center and its degree of hybridization with sodium polysulfides(NaPSs).An increased charge transfer leads to a shift of the alloy’s d-band center closer to the Fermi energy level,thereby enhancing its adsorption and catalytic capabilities.Among the three alloy compositions,the FeNi alloy exhibits the highest charge transfer.Consequently,the FeNi alloy demonstrates the superior electrochemical performance,achieving a high reversible specific capacity of 848.2 mA h g^(−1),with an average capacity degradation rate of only 0.037%per cycle over 1000 cycles at 1.2 C.The S/FeNi/NC cathode exhibits a low electrolyte-to-sulfur(E/S)ratio of 6.6µL mg^(−1),while maintaining a high reversible specific capacity of 568.1 mA h g^(−1).This offers valuable insights for the application of alloy catalysts in the S/FeNi/NC cathode of RT Na-S batteries.展开更多
In this study,we meticulously designed a layered carbon-based catalytic material to induce the degradation of a series of organic pollutants by activating peroxymonosulfate(PMS) in the PMS-based advanced oxidation pro...In this study,we meticulously designed a layered carbon-based catalytic material to induce the degradation of a series of organic pollutants by activating peroxymonosulfate(PMS) in the PMS-based advanced oxidation processes(AOPs).Results indicated that the silicon and oxygen elements from the montmorillonite were incorporated into the catalyst matrix to form the Si-O-C structure.It was notable that the layered carbonaceous material with Si-O-C structure exhibited an outstanding catalytic effect on the synthesized layered catalytic material array,achieving over 90 % removal rate of most pollutants within 60 min.It was notable that the layered carbonaceous material with Si-O-C structure exhibited an outstanding catalytic effect on the synthesized layered catalytic material array.The salt bridge system confirmed that pollutants can provide electrons to the Si-O-C/PMS system,and we verified that the electron transfer process(ETP) mechanism was the main pathway for the degradation of pollutants in the Si-O-C/PMS system via the open-circuit potential analysis.In combination with the structural properties of different pollutants,we discovered that electron-donating pollutants can supply more electrons to the Si-O-C/PMS system,thereby enhancing the ETP process.The findings of this study are anticipated to advance the development and practical application of layered carbonaceous materials-based catalysts and support the design and implementation of nanoconfined catalysts in the field of AOPs.展开更多
In recent years,with the rapid advancement of artificial intelligence,object detection algorithms have made significant strides in accuracy and computational efficiency.Notably,research and applications of Anchor-Free...In recent years,with the rapid advancement of artificial intelligence,object detection algorithms have made significant strides in accuracy and computational efficiency.Notably,research and applications of Anchor-Free models have opened new avenues for real-time target detection in optical remote sensing images(ORSIs).However,in the realmof adversarial attacks,developing adversarial techniques tailored to Anchor-Freemodels remains challenging.Adversarial examples generated based on Anchor-Based models often exhibit poor transferability to these new model architectures.Furthermore,the growing diversity of Anchor-Free models poses additional hurdles to achieving robust transferability of adversarial attacks.This study presents an improved cross-conv-block feature fusion You Only Look Once(YOLO)architecture,meticulously engineered to facilitate the extraction ofmore comprehensive semantic features during the backpropagation process.To address the asymmetry between densely distributed objects in ORSIs and the corresponding detector outputs,a novel dense bounding box attack strategy is proposed.This approach leverages dense target bounding boxes loss in the calculation of adversarial loss functions.Furthermore,by integrating translation-invariant(TI)and momentum-iteration(MI)adversarial methodologies,the proposed framework significantly improves the transferability of adversarial attacks.Experimental results demonstrate that our method achieves superior adversarial attack performance,with adversarial transferability rates(ATR)of 67.53%on the NWPU VHR-10 dataset and 90.71%on the HRSC2016 dataset.Compared to ensemble adversarial attack and cascaded adversarial attack approaches,our method generates adversarial examples in an average of 0.64 s,representing an approximately 14.5%improvement in efficiency under equivalent conditions.展开更多
Theoretical calculations serve as an effective method for determining plasma temperatures within planetary atmospheres.To simulate plasma temperature,a comprehensive implementation of the energy equation is used,which...Theoretical calculations serve as an effective method for determining plasma temperatures within planetary atmospheres.To simulate plasma temperature,a comprehensive implementation of the energy equation is used,which is governed by five terms:conductivity,heating,cooling,adiabatic expansion,and advection.The derivations mentioned are strongly dependent on the collision cross section between electrons and other particles(e.g.,neutrals,ions).It is notable that the momentum transfer cross sections between electrons and neutrals have been updated in recent decades.However,the widely used momentum average collision cross sections between electrons and neutrals,derived from the momentum transfer cross sections,are collected in studies dating back nearly half a century.Therefore,it becomes imperative to revise the momentum average collision cross sections relevant to astrophysical contexts,based on the latest studies.In this study,we summarize the momentum average collision cross sections of 13 species common in planetary atmospheres:H,H_(2),He,O,CH_(4),H_(2)O,CO,N_(2),O_(2),Ar,CO_(2),N_(2)O,and NO_(2).All results are derived from the latest studies concerning the electron-neutral collision cross section and are compared with previous studies.Furthermore,we present a comparison of the derived total electron-neutral collision frequency at Mars between this study and previous studies.Prominent differences in the total electron-neutral collision frequency between this and prior studies support the significance of updating the momentum average collision cross section between electrons and neutrals in studying the planetary atmospheres.展开更多
Air-permeable and ultrathin conductive electrodes are essential for next-generation soft electronics,including breathable wearables,on-skin devices and biointegrated electronics.However,conventional metallization stra...Air-permeable and ultrathin conductive electrodes are essential for next-generation soft electronics,including breathable wearables,on-skin devices and biointegrated electronics.However,conventional metallization strategies,such as sputtering and ink-printing,often suffer from severe vertical charge leakage due to the porous and ultrathin characteristics of nanofibrous networks,leading to device short-circuiting,operational failure and limited vertical integration.Here,we present a solvent-selective dissolutionassisted transfer printing strategy to achieve surface-confined metallization of ultrathin,lightweight,and gas-permeable nanofibrous networks,enabling lateral conductivity while maintaining vertical insulation.This transfer printing process facilitates not only the rapid formation of conductive patterns on the surface of nanofibrous networks but also mechanical reinforcement through solvent evaporation-induced interlocked fiber-fiber welding.Meanwhile,the strategy preserves the high permeability of the nanofibrous networks and imparts a unique combination of surface conductivity(2Ωcm)and vertical insulativity(10^(11)Ωcm).The resulting anisotropic conductive networks enable low-voltage wearable heaters,high-sensitive pressure sensors,and ultralight temperature sensors.A pressure-temperature dual-modal sensing patch is further fabricated for intelligent grasping classification.The proposed surface-confined metallization strategy enables rapid fabrication of an anisotropic conductive network as a building block to construct air-permeable,ultrathin and lightweight wearable electronics.展开更多
文摘A novel method for synthesis of quinazoline through the hydrogen transfer/annulation reaction using 2-nitrobenzyl alcohol and benzylamine as starting materials is presented.The reaction is catalyzed by a ruthenium(II)complex bearing a N-heterocyclic carbene nitrogen phosphine(CNP)ligand.The pronouncedα-donating capacity of the carbene within the CNP ligand of the catalyst plays a crucial role in stabilizing the catalytically active species.Additionally,the hemilability of the nitrogen facilitates the creation of coordination vacancies,which are essential for the activation of reaction substrate molecules.The synergistic interplay between these two functionalities markedly enhances catalytic efficiency.This catalytic system shows the significant catalytic activity and selectivity,along with a broad substrate adaptability.All substrates yield the target product in good to excellent yields with the maximum yield reaching 95%.Control experiments have substantiated that benzaldehyde and phenylmethanimine may serve as intermediates in the reaction,thereby reinforcing the role of benzylamine as both a hydrogen donor and a nitrogen source in the process.
基金supported by the Natural Science Foundation of Jiangsu Province(No.BK20220409)the National Natural Science Foundation of China(No.22401153)+2 种基金the FWO[Fund for Scientific Research-Flanders(Belgium)]for financial support(recipient Erik V.Van der Eycken)the Research Council of the KU Leuven(recipient Erik V.Van der Eycken)the support of the"RUDN University Strategic Academic Leadership Program"(recipient Erik V.Van der Eycken).
文摘Peptides play important roles in chemistry,medicinal chemistry and life science,due to their high efficiency and specificity,unusual biological and therapeutic properties.As naturally occurring peptides often face with their intrinsic limitations including metabolic instability and low membrane permeability,the strategies for synthesizing unnatural amino acids and peptides are explored.Among the methods for modifying amino acids and peptides,chemo-and site-selective approaches are preferred because of the ability to fine-tuning structural features.Recently,transition metal-catalyzed Csingle bondH activation has been employed for the functionalization of amino acids and peptides.Through domino Csingle bondH activation/annulation,a series of structurally complex and diverse amino acids and peptides is constructed.This review highlights recent advances in the synthesis of unnatural amino acids and peptides via transition metal-catalyzed Csingle bondH activation/annulation.
文摘An efficient strategy for construction of tricyclic thiazino[3,4-a]isoquinolines has been achieved via 4-dimethylamino-pyridine(DMAP)promoted[5+1]annulation of simple and readily available isoquinoline 1,4-zwitterion withα-bromoketone.This protocol showed good substrate compatibility as an array of structurally and electronically diverse thiazino[3,4-a]isoquinolines prepared efficiently in moderate to good yields.It is particularly emphasized that although this reaction exhibits moderate stereoselectivity,the two diastereomers can be separated by column chromatography,providing an important molecular diversity foundation for the screening and structural optimization of subsequent drug lead compounds,as well as a simple and efficient method for constructing complex nitrogen-containing and sulfur-containing heterocyclic compounds.It has potential application value in the fields of medicinal chemistry and organic synthesis.
基金financially supported by the National Natural Science Foundation of China(No.21572271).
文摘A[3+4]annulation of α-substituted allenes and Schiff bases is reported.This methodology serves as a conduit for the construction of a series of biologically important benzazepine derivatives in good to excellent yields under mild conditions by an unprecedented mode involving β’-carbon of α-substituted allenes and the proposed mechanism is supported by capturing the intermediate.Moreover,this class of benzazepine derivatives exhibited potential ability of cytotoxicity toward cancer cells.
基金support from the National Natural Science Foundation of China(Nos.22061017 and21862006)the Science and Technology program of Gansu Province(Nos.22YF7GG127 and 23JRRG0002)+1 种基金National innovative training program for college students(No.202310740015)the Open Project Funding of Hubei Key Laboratory of Processing and Application of Catalytic materials(No.202306004)。
文摘Designing efficient,recyclable,and low-cost catalysts is crucial for the synthesis of quinoxaline derivatives.In this context,a novel N-stable Co_(2)P nano-catalyst(CoP@N–C-1.5)was developed using a templatesacrificial approach.The catalyst demonstrated a broad substrate scope and good functional group tolerance,achieving yields of up to 84%.Additionally,the catalyst exhibited reusability and can be recycled up to three times.The CoP@N–C-1.5 was characterized using X-ray powder diffraction(XRD),scanning electron microscopy(SEM),and transmission electron microscopy(TEM).The results indicated that the catalyst contained Co2P nanoparticles.The X-ray photoelectron spectroscopy(XPS)further confirms the presence of Co-P.Analysis of the characterization data and experimental results revealed that the active site of the catalyst comprises N-stable Co_(2)P nanoparticles.
基金financially supported by National Natural Science Foundation of China(No.22161022).
文摘Chromones serve as versatile heterocyclic scaffolds and are common core structural units in a variety of natural products and bioactive organic molecules.This area of research,at the forefront of organic synthesis,has seen remarkable progress in recent years.Among the various synthetic methodologies for accessing chromone scaffolds,the tandem annulation of o-hydroxyaryl enaminones has emerged as a robust and practical strategy.This approach,through direct vinyl C-H bond functionalization of o-hydroxyaryl enaminones,enables the construction of structurally diverse chromones(including 3-substituted chromones,2-substituted chromones,and 2,3-disubstituted chromones)and their derivatives since mid-2019.In this review,we highlight recent advances in the synthesis of various types of chromones and their derivatives,achieved through tandem direct vinyl C-H activation and chromone annulation of o-hydroxyaryl enaminones.
基金the National Natural Science Foundation of China(Nos.22171147 and 21871148)for the financial support。
文摘Polycyclic compounds are widely found in natural products and drug molecules with important biological activities,which attracted the attention of many chemists.Phosphine-catalyzed nucleophilic addition is one of the most powerful tools for the construction of various cyclic compounds with the advantages of atom economy,mild reaction conditions and simplicity of operation.Allenolates,Morita−Baylis−Hillman(MBH)alcohols and their derivatives(MBHADs),electron-deficient olefins and alkynes are very efficient substrates in phosphine mediated annulations,which formed many phosphonium species such asβ-phosphonium enolates,β-phosphonium dienolates and vinyl phosphonium ylides as intermediates.This review describes the reactivities of these phosphonium zwitterions and summarizes the synthesis of polycycle compounds through phosphine-mediated intramolecular and intermolecular sequential annulations.Thus,a systematic summary of the research process based on the phosphine-mediated sequential annulations of allenolates,MBH alcohols and MBHADs,electron-deficient olefins and alkynes are presented in Chapters 2-6,respectively.
基金National Natural Science Foundation of China(Nos.21971090 and 22271123)the NSF of Jiangsu Province(No.BK20230201)+1 种基金the Natural Science Foundation of Jiangsu Education Committee(No.22KJB150024)the Natural Science Foundation of Jiangsu Normal University(No.21XSRX010)。
文摘A new oxidative N-heterocyclic carbene(NHC)-catalyzed high-order[7+3]annulation reaction ofγ-indolyl phenols as 1,7-dinucleophiles andα,β-alkynals with the aid of Sc(OTf)_(3)is reported,enabling the highly regioselective access to unprecedented polyarene-fused ten-membered lactams bearing a bridged aryl-aryl-indole scaffold in moderate to good yields.This protocol demonstrates a broad substrate scope,good compatibility with substituents and complete regioselectivity,providing an organocatalytic modular synthetic strategy for creating medium-sized lactams.
基金financially supported by National Key Research and Development Programs (Nos.2022YFD1700403 and 2023YFD1700303)National Natural Science Foundation of China (Nos.12274128 and 12250003)+2 种基金Shanghai Rising-Star Program (No.21QA1402600)the support of NYU-ECNU Center for Computational Chemistry at NYU Shanghaithe University of Bath and the Open Research Fund of the School of Chemistry and Chemical Engineering,Henan Normal University (No.2020ZD01) for support。
文摘Fluorescent probes based on intramolecular charge transfer(ICT) have obvious advantages for accurate quantitative analysis.To obtain high-performance ratiometric probes requires distinct photophysical properties during recognition reaction process,which is closely related to their ICT characteristics.1,8-Naphthalimide is known as a typical fluorophore with desirable ICT property when functionalized with an electron-donating moiety at the para-position of the naphthalene chromophore.Although the photophysical properties of para-substituted 1,8-naphthalimide have been well studied,its meta-substituted counterpart has not been fully evaluated since the meta-position is conventionally thought to be weakly conjugated.Herein,combined experimental and theoretical studies are performed which consistently indicate that stronger charge transfer(CT) is exhibited by the meta-amino substituted 1,8-naphthalimide(m-NH_(2)) compared to the para-amino substituted one(p-NH_(2)).The ratiometric response of fluorescence with significant changes in wavelength and intensity upon acetylation(m-NAc and p-NAc) can be attributed to the larger ICT and stronger-NH_(2) vibrations.This observation is further demonstrated by deuterium oxide experiments,viscosity experiments and quantum chemical calculations.The practical application of meta-amino-1,8-naphthalimide ICT-based probes is also confirmed.This research is expected to bring an in-depth understanding of π-conjugated systems with ICT characteristics,and facilitates the design of sensitive ICT fluorescent probes with meta-amino substitution.
基金the National Natural Science Foundation of China(22208320)the Science and Technology Program of Henan Province(212102210044)The Henan Association for Science and Technology Youth Talent Support Program(2022HYTP026).
文摘Combining the advantages of high efficiency,low-pressure drop,and large throughput,the pore arrayenhanced tube-in-tube microchannel(PA-TMC) is a promising microreactor for industrial applications.However,most of the mass transfer takes place in the upstream pore region,while the contribution of the downstream annulus is limited.In this work,helical wires were introduced into the annulus by adhering to the outer surface of the inner tube.Mixing behavior and mass transfer of liquid-liquid twophase flow in PA-TMC with different helical wires have been systematically studied by a combination of experiments and volume of fluid(VOF) method.The introduction of helical wires improves the overall volumetric mass transfer coefficient KLa by up to 133% and the mass transfer efficiency E by up to 117%.The simulation results show that the helical wire brings extra phase mixing regions and increases the specific interface area,while accelerating the fluid flow and expanding the area of enhanced turbulent dissipation rate.Influences of helical wires in various configurations are compared by the comprehensive index I concerning the pressure drop and mass transfer performance simultaneously and a new correlation between KLa and specific energy consumption φ is proposed.This research deepens the understanding of the mixing behavior and mass transfer in the PA-TMCs and provides practical experience for the process intensification of microchannel reactors.
基金financial support from the schoollevel research projects of Yancheng Institute of Technology(No.xjr2020044)the National Natural Science Foundation of China(Nos.22101152,22271123 and 21971090)。
文摘Catalytic C–H activation-initiated annulation reactions have emerged as a versatile strategy for the efficient construction of diverse ring structural units and complex cyclic molecules in synthetic chemistry.Herein,we describe a new Rh(Ⅲ)-catalyzed C–H activation-initiated transdiannulation reaction of N,Ndimethyl enaminones with gem-difluorocyclopropenes in the presence of H_(2)O,enabling a facile and oxygen transfer access to ring-fluorinated tricyclicγ-lactones with a 6-5 ring-junction tetrasubstituted stereocenter.This approach features bond-forming/annulation efficiency,good functional group tolerance and complete regioselectivity,which may include a complex process consisting of Rh(Ⅲ)-catalyzed C(sp2)–H activation,cyclic alkene insertion,defluorinated ring-opening of gem-difluorocyclopropane,intramolecular oxygen transfer,intramolecular cyclization and oxidative hydration.
基金supported by the National Natural Science Foundation of China (22472031,U24A20567,22032002)the 111 Project。
文摘A visible-light-induced synergistic hydrogen atom transfer(HAT)and proton transfer(PT)catalysis was developed for the defluorinative carboxylation of α-CF_(2)R-substituted alkenes.This system affords a variety of γ,γ-difluoro-and γ-monofluoro-vinylacetic acids without stepwise acidification,exhibiting good functional group tolerance,broad scope,and facile scalability.Mechanism studies support that thiol plays the role of the hydrogen relay,which s a hydrogen atom through HAT and then outputs a proton via PT.This strategy also takes full advantage of formate for photocatalytic carboxylation reaction in a step-and atomeconomical way.
文摘This study investigates the enhancement of convective heat transfer in a serpentine pipe using ferrofluid flow influenced by dual non-uniform magnetic sources.The primary objective is to improve thermal performance in compact cooling systems,such as those used in heat exchangers.A two-dimensional,steady-state Computational Fluid Dynamic(CFD)model is developed in ANSYS Fluent to simulate the behavior of an incompressible ferrofluid under applied constant heat flux and magnetic fields.The magnetic force is modeled using the Kelvin force,which acts on magnetized nanoparticles in response to spatially varying electromagnetic fields generated by two strategically positioned current-carrying wires.The effects of magnetic field strength,quantified by the magnetic number(Mn),on flow behavior and temperature distribution are thoroughly analyzed.The results indicate that increasing Mn leads to higher Nusselt numbers,demonstrating enhanced convective heat transfer.Secondary vortices induced by magnetic forcing improve fluid mixing,particularly in curved regions of the pipe.A mesh-independence study and model validation with benchmark data support the reliability of the numerical framework.This work highlights the potential of magnetic-field-assisted thermal control in energy-efficient cooling applications and provides a foundation for the further development of advanced ferrofluid-based heat transfer systems.
文摘Accurate assessment of seismic landslide susceptibility is crucial for disaster prevention and emergency decision-making.Although machine learning methods have been widely applied in this field,they exhibit a strong dependence on large quantities of highquality samples,resulting in significantly low prediction accuracy of existing studies under data-scarce or crossregional prediction scenarios,which fail to meet practical application requirements.To address this issue,this study proposes an intelligent prediction model integrating transfer learning and a sampling optimization strategy,aiming to enhance the accuracy and applicability of seismic landslide susceptibility assessment.The model first improves the sample collection method through the sampling optimization strategy to enhance the precision and representativeness of training samples.This not only ensures the accuracy of origin area training but also further strengthens the model's predictive ability in the target area.Subsequently,it incorporates Transfer Component Analysis(TCA)to overcome the differences in environmental characteristics between the origin area and target area,and couples TCA with the Light GBM algorithm to construct the TCA-Light GBM model,realizing the assessment of seismic landslide susceptibility in sample-free areas.Validated through case studies of the Jiuzhaigou and Luding earthquakes,the results demonstrate that the proposed TCALight GBM transfer learning method exhibits excellent applicability in seismic landslide susceptibility prediction.After optimization with the TCA algorithm,the model's prediction performance in the target domain is significantly improved,with the AUC value increasing from 0.719 to 0.827,representing an increase of approximately 15.02%.This indicates that TCA technology can effectively alleviate the feature distribution discrepancy between the source domain and target domain,enhancing the model's generalization ability.The method is particularly suitable for scenarios with data scarcity and cross-regional prediction and can provide reliable technical support for the emergency response and risk prevention and control of seismic hazards.
基金National Natural Science Foundation of China (Nos.22071185 and 22271224)the Fundamental Research Funds for the Central Universities (No.2042019kf0008)Wuhan University startup funding for financial support。
文摘The development of catalytic multicomponent reactions for constructing complex organic scaffolds from readily accessible commodity chemicals is a key pursuit in contemporary synthetic chemistry.Current methods for synthesizing thioesters primarily rely on the acylation of thiols,which produces substantial waste and requires malodorous,unstable sulfur sources.In this work,we introduce a photocatalyzed hydrogen transfer strategy that enables a three-component synthesis of thioesters using abundant primary alcohols,easily available alkenes and elemental sulfur under mild conditions.This protocol demonstrates broad applicability and high chemo-and regioselectivity for both primary alcohols and alkenes,highlighting the advantage and potential of photo-mediated hydrogen transfer in facilitating multicomponent reactions using primary alcohol and elemental sulfur feedstocks.
基金supported by Shaanxi Fundamental Science Research Project for Chemistry and Biology(23JHQ011)Natural Science Foundation of Shaanxi(2024JC-YBMS-115)Natural Science Basic Research Plan in Shaanxi Province of China(2025JC-YBMS-141)。
文摘The severe shuttle effect and sluggish reaction kinetics in room-temperature sodium-sulfur(RT Na-S)batteries have been major bottlenecks hindering their practical application.To overcome these challenges,a straightforward reduction approach was employed to design three bimetallic alloy nanoparticles(FeNi,FeCo,and NiCo)supported on multistage porous carbon substrates.Experimental and theoretical calculations reveal that the charge transfer within the alloy catalyst influences the position of its d-band center and its degree of hybridization with sodium polysulfides(NaPSs).An increased charge transfer leads to a shift of the alloy’s d-band center closer to the Fermi energy level,thereby enhancing its adsorption and catalytic capabilities.Among the three alloy compositions,the FeNi alloy exhibits the highest charge transfer.Consequently,the FeNi alloy demonstrates the superior electrochemical performance,achieving a high reversible specific capacity of 848.2 mA h g^(−1),with an average capacity degradation rate of only 0.037%per cycle over 1000 cycles at 1.2 C.The S/FeNi/NC cathode exhibits a low electrolyte-to-sulfur(E/S)ratio of 6.6µL mg^(−1),while maintaining a high reversible specific capacity of 568.1 mA h g^(−1).This offers valuable insights for the application of alloy catalysts in the S/FeNi/NC cathode of RT Na-S batteries.
基金supported by National Natural Science Foundation of China (Nos.52170086,22476116,52074176)Natural Science Foundation of Shandong Province (Nos.ZR2021ME013,ZR2024ME156,ZR2022QB250)。
文摘In this study,we meticulously designed a layered carbon-based catalytic material to induce the degradation of a series of organic pollutants by activating peroxymonosulfate(PMS) in the PMS-based advanced oxidation processes(AOPs).Results indicated that the silicon and oxygen elements from the montmorillonite were incorporated into the catalyst matrix to form the Si-O-C structure.It was notable that the layered carbonaceous material with Si-O-C structure exhibited an outstanding catalytic effect on the synthesized layered catalytic material array,achieving over 90 % removal rate of most pollutants within 60 min.It was notable that the layered carbonaceous material with Si-O-C structure exhibited an outstanding catalytic effect on the synthesized layered catalytic material array.The salt bridge system confirmed that pollutants can provide electrons to the Si-O-C/PMS system,and we verified that the electron transfer process(ETP) mechanism was the main pathway for the degradation of pollutants in the Si-O-C/PMS system via the open-circuit potential analysis.In combination with the structural properties of different pollutants,we discovered that electron-donating pollutants can supply more electrons to the Si-O-C/PMS system,thereby enhancing the ETP process.The findings of this study are anticipated to advance the development and practical application of layered carbonaceous materials-based catalysts and support the design and implementation of nanoconfined catalysts in the field of AOPs.
文摘In recent years,with the rapid advancement of artificial intelligence,object detection algorithms have made significant strides in accuracy and computational efficiency.Notably,research and applications of Anchor-Free models have opened new avenues for real-time target detection in optical remote sensing images(ORSIs).However,in the realmof adversarial attacks,developing adversarial techniques tailored to Anchor-Freemodels remains challenging.Adversarial examples generated based on Anchor-Based models often exhibit poor transferability to these new model architectures.Furthermore,the growing diversity of Anchor-Free models poses additional hurdles to achieving robust transferability of adversarial attacks.This study presents an improved cross-conv-block feature fusion You Only Look Once(YOLO)architecture,meticulously engineered to facilitate the extraction ofmore comprehensive semantic features during the backpropagation process.To address the asymmetry between densely distributed objects in ORSIs and the corresponding detector outputs,a novel dense bounding box attack strategy is proposed.This approach leverages dense target bounding boxes loss in the calculation of adversarial loss functions.Furthermore,by integrating translation-invariant(TI)and momentum-iteration(MI)adversarial methodologies,the proposed framework significantly improves the transferability of adversarial attacks.Experimental results demonstrate that our method achieves superior adversarial attack performance,with adversarial transferability rates(ATR)of 67.53%on the NWPU VHR-10 dataset and 90.71%on the HRSC2016 dataset.Compared to ensemble adversarial attack and cascaded adversarial attack approaches,our method generates adversarial examples in an average of 0.64 s,representing an approximately 14.5%improvement in efficiency under equivalent conditions.
基金the National Natural Science Foundation of China through Grants 42261160643,42441806,42241114,and 42304166supported by the open project funded by the Key Laboratory of Geospace Environment,Chinese Academy of Sciences,University of Science and Technology of China.
文摘Theoretical calculations serve as an effective method for determining plasma temperatures within planetary atmospheres.To simulate plasma temperature,a comprehensive implementation of the energy equation is used,which is governed by five terms:conductivity,heating,cooling,adiabatic expansion,and advection.The derivations mentioned are strongly dependent on the collision cross section between electrons and other particles(e.g.,neutrals,ions).It is notable that the momentum transfer cross sections between electrons and neutrals have been updated in recent decades.However,the widely used momentum average collision cross sections between electrons and neutrals,derived from the momentum transfer cross sections,are collected in studies dating back nearly half a century.Therefore,it becomes imperative to revise the momentum average collision cross sections relevant to astrophysical contexts,based on the latest studies.In this study,we summarize the momentum average collision cross sections of 13 species common in planetary atmospheres:H,H_(2),He,O,CH_(4),H_(2)O,CO,N_(2),O_(2),Ar,CO_(2),N_(2)O,and NO_(2).All results are derived from the latest studies concerning the electron-neutral collision cross section and are compared with previous studies.Furthermore,we present a comparison of the derived total electron-neutral collision frequency at Mars between this study and previous studies.Prominent differences in the total electron-neutral collision frequency between this and prior studies support the significance of updating the momentum average collision cross section between electrons and neutrals in studying the planetary atmospheres.
基金supported by the National Natural Science Foundation of China(22434007,22104021,52303075,22404102)the Taishan Young Scholar Program of Shandong Province(tsqnz20231235)+2 种基金the Natural Science Foundation of Shandong Province(ZR2024QB338,ZR2023QB227)the Higher Education Institutions Youth Innovation Team Plan of Shandong Province(2024KJH046)the Shandong Postdoctora1 Science Foundation(SDCX-ZG-202400279)。
文摘Air-permeable and ultrathin conductive electrodes are essential for next-generation soft electronics,including breathable wearables,on-skin devices and biointegrated electronics.However,conventional metallization strategies,such as sputtering and ink-printing,often suffer from severe vertical charge leakage due to the porous and ultrathin characteristics of nanofibrous networks,leading to device short-circuiting,operational failure and limited vertical integration.Here,we present a solvent-selective dissolutionassisted transfer printing strategy to achieve surface-confined metallization of ultrathin,lightweight,and gas-permeable nanofibrous networks,enabling lateral conductivity while maintaining vertical insulation.This transfer printing process facilitates not only the rapid formation of conductive patterns on the surface of nanofibrous networks but also mechanical reinforcement through solvent evaporation-induced interlocked fiber-fiber welding.Meanwhile,the strategy preserves the high permeability of the nanofibrous networks and imparts a unique combination of surface conductivity(2Ωcm)and vertical insulativity(10^(11)Ωcm).The resulting anisotropic conductive networks enable low-voltage wearable heaters,high-sensitive pressure sensors,and ultralight temperature sensors.A pressure-temperature dual-modal sensing patch is further fabricated for intelligent grasping classification.The proposed surface-confined metallization strategy enables rapid fabrication of an anisotropic conductive network as a building block to construct air-permeable,ultrathin and lightweight wearable electronics.
