Carbenes as one of the most important class of intermediates have been widely utilized in various organic synthetic transformations.Carbene insertion-initiated ring-opening reactions of cyclic ethers offer a valuable ...Carbenes as one of the most important class of intermediates have been widely utilized in various organic synthetic transformations.Carbene insertion-initiated ring-opening reactions of cyclic ethers offer a valuable strategy for constructing new carbon-oxygen bonds.In comparison with traditional thermal or metal-mediated carbene transfer reactions,visible-light-promoted multi-component reaction strategy provides a mild and eco-friendly approach to access densely functionalized molecules.Recently,visible-light-induced multi-component carbene transfer reactions of diazo compounds have been rapidly developed and attracted a great deal of research interest of chemists owing to their advantages of simple operation,mild condition,high atom economy and rich structural diversity.This paper summarizes the recent research progress on the visible-light-promoted multi-component carbene transfer reactions of diazo compounds via ring-opening of cyclic ethers with various nucleophiles.The reaction patterns of different nucleophiles and their corresponding mechanism are described in this review.The future research direction and challenges in this area are also discussed.展开更多
Silica nanoparticles-stabilized cobalt and nitrogen-doped carbon materials were synthesized through pyrolysis of metal-organic-framework of ZIF-67 supported by silica nanoparticles.The experimental results reveal that...Silica nanoparticles-stabilized cobalt and nitrogen-doped carbon materials were synthesized through pyrolysis of metal-organic-framework of ZIF-67 supported by silica nanoparticles.The experimental results reveal that the introduction of the silica nanoparticles can stabilize the microstructure of the derived CoN-C materials,which in turn exhibits the promising electrocatalytic activity towards both oxygen reduction and oxygen evolution reactions.The optimized sample exhibits a better oxygen reduction activity than commercial Pt/C catalyst as confirmed by the positive shift of half-wave potential by 20 mV while it has a low overpotential of 273 mV for oxygen evolution reactions with the retained performance over 80%after 25,000 s of continuous operation.It is demonstrated that the introduction of support frame might be an effective way to improve the activity and stability of metal-organic-framework derived electrocatalyst with stabilized microstructure.展开更多
The sulfation and decomposition process has proven effective in selectively extracting lithium from lepidolite.It is essential to clarify the thermochemical behavior and kinetic parameters of decomposition reactions.A...The sulfation and decomposition process has proven effective in selectively extracting lithium from lepidolite.It is essential to clarify the thermochemical behavior and kinetic parameters of decomposition reactions.Accordingly,comprehensive kinetic study by employing thermalgravimetric analysis at various heating rates was presented in this paper.Two main weight loss regions were observed during heating.The initial region corresponded to the dehydration of crystal water,whereas the subsequent region with overlapping peaks involved complex decomposition reactions.The overlapping peaks were separated into two individual reaction peaks and the activation energy of each peak was calculated using isoconversional kinetics methods.The activation energy of peak 1 exhibited a continual increase as the reaction conversion progressed,while that of peak 2 steadily decreased.The optimal kinetic models,identified as belonging to the random nucleation and subsequent growth category,provided valuable insights into the mechanism of the decomposition reactions.Furthermore,the adjustment factor was introduced to reconstruct the kinetic mechanism models,and the reconstructed models described the kinetic mechanism model more accurately for the decomposition reactions.This study enhanced the understanding of the thermochemical behavior and kinetic parameters of the lepidolite sulfation product decomposition reactions,further providing theoretical basis for promoting the selective extraction of lithium.展开更多
Metal halide perovskites(MHPs)with striking electrical and optical properties have appeared at the forefront of semiconductor materials for photocatalytic redox reactions but still suffer from some intrinsic drawbacks...Metal halide perovskites(MHPs)with striking electrical and optical properties have appeared at the forefront of semiconductor materials for photocatalytic redox reactions but still suffer from some intrinsic drawbacks such as inferior stability,severe charge-carrier recombination,and limited active sites.Heterojunctions have recently been widely constructed to improve light absorption,passivate surface for enhanced stability,and promote charge-carrier dynamics of MHPs.However,little attention has been paid to the review of MHPs-based heterojunctions for photocatalytic redox reactions.Here,recent advances of MHPs-based heterojunctions for photocatalytic redox reactions are highlighted.The structure,synthesis,and photophysical properties of MHPs-based heterojunctions are first introduced,including basic principles,categories(such as Schottky junction,type-I,type-II,Z-scheme,and S-scheme junction),and synthesis strategies.MHPs-based heterojunctions for photocatalytic redox reactions are then reviewed in four categories:H2evolution,CO_(2)reduction,pollutant degradation,and organic synthesis.The challenges and prospects in solar-light-driven redox reactions with MHPs-based heterojunctions in the future are finally discussed.展开更多
The differences in the competitive reactions of hydrogarnet and quicklime when reacting with titaniumcontaining and silicon-containing minerals during the Bayer digestion process were investigated.Thermodynamic analys...The differences in the competitive reactions of hydrogarnet and quicklime when reacting with titaniumcontaining and silicon-containing minerals during the Bayer digestion process were investigated.Thermodynamic analysis,artificial mineral experiments,and an evaluation of the digestion effect of natural diasporic bauxite were conducted.The results indicate that hydrogarnet shows a preferential reaction with anatase,and this preference becomes more pronounced as the silicon saturation coefficient increases.In contrast,quicklime participates in non-selective reactions with both anatase and desilication products(DSP).The preference of hydrogarnet for anatase significantly enhances the utilization efficiency of CaO in the high-temperature Bayer digestion process.展开更多
To develop specific lining materials for rare earth steel nozzles,LaAlO_(3)powder was first synthesized by high-temperature solid-phase synthesis at 1400℃for 3 h using La_(2)O_(3)and Al_(2)O_(3)powders as raw materia...To develop specific lining materials for rare earth steel nozzles,LaAlO_(3)powder was first synthesized by high-temperature solid-phase synthesis at 1400℃for 3 h using La_(2)O_(3)and Al_(2)O_(3)powders as raw materials.Then BN,AlN,Si_(3)N_(4)and TiN powders were pressed intoφ30 mm×7 mm substrate samples under 120 MPa with PVA as the binder.Equal amounts of La_(2)O_(3)and LaAlO_(3)powders were placed on their surfaces,reacting at 1550℃for 3 h in different atmospheres(reducing and argon conditions).The interfacial reactions of the four nitride(BN,Si_(3)N_(4),AlN,and TiN)substrate samples with La_(2)O_(3)and LaAlO_(3)in different atmospheres were studied,respectively.The results show that in reducing and argon atmospheres,the intensity order of the reactions between the four nitrides and La_(2)O_(3)is Si_(3)N_(4)>BN>AlN>TiN.In the reducing atmosphere,the reaction intensity order of the four nitrides with LaAlO_(3)is Si_(3)N_(4)>AlN≈TiN>BN.However,in the argon atmosphere,the order is Si_(3)N_(4)>BN>AlN≈TiN.TiN has good structural stability in both reducing and argon atmospheres,and shows weak reactivity with La_(2)O_(3)and LaAlO_(3).It is a relatively good anti-clogging lining material for rare earth steel nozzles.展开更多
Organometallics play a vital role in catalytic and synthetic processes.Understanding the indi-vidual elementary steps of the reactions of organo metallic com-pounds is crucial for the development and ratio-nal design ...Organometallics play a vital role in catalytic and synthetic processes.Understanding the indi-vidual elementary steps of the reactions of organo metallic com-pounds is crucial for the development and ratio-nal design of new organometallic reagents and catalysts.Study of gas-phase reactions is one of the key approaches to probing the individual elementary steps under isolated and re-producible conditions.A series of investigations have been reported on the gas-phase reac-tions between organometallic ions and neutral molecules under room temperature conditions.However,studies about the reactions between organometallic ions and neutral molecules un-der heating conditions are very limited.In this work,an apparatus with an electrospray ion-ization source and an ion funnel trap,which can be coupled with a high-temperature linear ion trap reactor,was designed and built.The apparatus can be used to investigate the reac-tions between organometallic ions and neutral molecules under heating conditions.By using the apparatus,the adsorption reactions of Rh(PPh_(3))_(2)^(+)+CO→Rh(PPh_(3))_(2)CO^(+)and CuPPh_(3)^(+)+CO_(2)→CuPPh_(3)CO_(2)+under variable temperature conditions have been conducted.The experiments showed that the reaction rate constant of Rh(PPh_(3))_(2)^(+)+CO increases first and then decreases with increasing temperature.In contrast,the rate constant of CuPPh_(3)^(+)+CO_(2)decreases monotonically as the temperature increases.Density functional theory calculations indicate that the adsorption reaction of Rh(PPh_(3))_(2)^(+)+CO→Rh(PPh_(3))_(2)CO^(+)is subject to a small barrier,while CuPPh_(3)^(+)+CO_(2)→CuPPh_(3)CO_(2)+is barri-erless,which is consistent with the experimentally observed temperature-dependent rate con-stants.The newly built apparatus can thus provide new kinetic information to address reac-tion mechanisms for organometallic ions.展开更多
We report for the first time the combination of directed evolution focused on enhancing and reversing the stereoselectivity of an enzyme with Cu(I)-mediated click chemistry(CuAAC),providing an asymmetric click approac...We report for the first time the combination of directed evolution focused on enhancing and reversing the stereoselectivity of an enzyme with Cu(I)-mediated click chemistry(CuAAC),providing an asymmetric click approach for versatile chiral triazoles products.In this study,the halohydrin dehalogenase HheG was used as the enzyme which was evolved to induce a stereoselective ring-opening reaction of cyclic epoxides in the presence of NaN3 with the formation of chiral azido products.Two mutants of opposite stereopreference were generated,which convert cyclohexene oxide as well as cycloheptene oxide to(1S,2S)-2-azidocyclohexanol,(1R,2R)-2-azidocyclohexanol,(1S,2S)-2-azidocycloheptanol and(1R,2R)-2-azidocycloheptanol with essentially high stereoselectivity.The chiral products were then subjected to CuAAC in reactions with structurally different alkynes.Since HheG was found to be compatible with Cu(I),the process was also performed successfully in a unique 2-step one-pot process leading to various chiral triazoles.In order to understand the enhancement and reversal of the evolved enantioselectivity,QM and MD computations were performed.This approach harnesses the modifiability and high stereoselectivity of the evolved biocatalysts in combination with click chemistry.It holds great potential for diverse fields,particularly in the area of pharmaceuticals.展开更多
This study presents an investigation into shock-induced exothermic reactions within three distinct aluminum-based energetic mixtures:aluminum/sulfur(Al/S),aluminum/copper oxide(Al/CuO),and aluminum/polytetrafluoroethy...This study presents an investigation into shock-induced exothermic reactions within three distinct aluminum-based energetic mixtures:aluminum/sulfur(Al/S),aluminum/copper oxide(Al/CuO),and aluminum/polytetrafluoroethylene(Al/PTFE).A challenge in current modeling efforts is accurately capturing the complex physical and chemical coupling under extreme loading,especially the influence of rapidly forming gaseous products in Al/PTFE mixtures on material integrity.To address this,a wide-range numerical model based on the Smoothed Particle Hydrodynamics(SPH)method was developed.This mesh-free approach manages large deformations and incorporates elastic-plastic flow,heat transfer,component diffusion,and chemical kinetics simulated using both zero-and first-order reaction schemes,favoring the latter for surface-reaction mechanisms.The proposed model takes into account gaseous reaction products,specifically aluminum fluoride(AlF3)to assess their impact on ampoule fracture dynamics.Numerical simulations,validated against experimental data,demonstrated that reaction rate,local pressure,and temperature are the primary controlling factors governing energy release and structural response.Comparative analysis revealed that although Al/CuO initiates reaction more readily(lower critical pressure/temperature),the Al/S mixture exhibits superior overall reaction efficiency under shock-wave loading,highlighting the significance of post-initiation kinetic factors.Furthermore,simulations using the conical ampoule geometry confirmed its effectiveness in generating a continuous pressure gradient,enabling systematic characterization of pressure-dependent reaction kinetics.This validated SPH model provides a powerful and predictive tool for understanding the complex behavior of energetic materials under shock-wave loading and aids in optimizing material composition for desired performance characteristics.展开更多
During the oxygen evolution reaction(OER),reconstruction of transition metal sulfides(TMSs)is inevitable.However,the lack of a clear theoretical understanding of this process has impeded the development of effective r...During the oxygen evolution reaction(OER),reconstruction of transition metal sulfides(TMSs)is inevitable.However,the lack of a clear theoretical understanding of this process has impeded the development of effective reconstruction regulation strategies.In this study,we first explored the reconstruction mechanism of CoS_(2)during OER from the perspective of electronic structure and identified two possible pathways:the OH-assisted mechanism and the O-assisted mechanism.Further verification showed that these mechanisms are universally applicable to other TMSs(e.g.,FeS_(2)).Based on the reconstruction mechanism,we investigated the basic reasons for the influence of various regulation strategies,such as vacancy modification and facet engineering,on the reconstruction ability.This verified that the method of analyzing the change in the reconstruction ability of catalysts based on the reconstruction mechanism has a high degree of applicability.Importantly,we proposed a core regulation strategy:the coordination symmetry regulation strategy.Specifically,by breaking the symmetry of the surface coordination environment of TMSs(such as introducing heteroatom doping or strain),the reconstruction process will be facilitated.Our findings provide a comprehensive mechanistic explanation for the reconstruction of TMS catalysts and offer a new idea for the rational design of OER catalysts with controllable reconstruction capacity.展开更多
Controversies and arguments about the origin of plan-etary water have aroused enthusiasm to search for possible chemical sources.Considering the CO_(2)-rich atmospheres of Mars,Venus,and the prebiotic Earth,we propose...Controversies and arguments about the origin of plan-etary water have aroused enthusiasm to search for possible chemical sources.Considering the CO_(2)-rich atmospheres of Mars,Venus,and the prebiotic Earth,we propose that chemical reactions between HOCO^(+)and H_(2)can contribute to the production of H_(2)O on the basis of high-level calculations.As for the reagents,HOCO^(+)can form via the protonation of CO_(2),while H+and H_(2)are from the solar wind or in-terstellar space.Note that one of the reaction path-ways undergoes multiple transition-state complexes and exhibits the roaming-like dynamics feature.More-over,intermolecular proton or hydrogen transfer is a key step in the production of H_(2)O,there-by H-tunneling effect profoundly enhances the reaction rate in a wide range of temperatures or collision energies.展开更多
An improved method is proposed for the extraction of the symmetry energy coefficient relative to the temperature,a_(sym)/T,in the heavy-ion reactions near the Fermi energy region,based on the modified Fisher Model.Thi...An improved method is proposed for the extraction of the symmetry energy coefficient relative to the temperature,a_(sym)/T,in the heavy-ion reactions near the Fermi energy region,based on the modified Fisher Model.This method is applied to the primary fragments of antisymmetrized molecular dynamics(AMD)simulations for ^(46)Fe+^(46)Fe,^(40)Ca+^(40)Ca and ^(48)Ca+^(48)Ca at 35 MeV/nucleon,in order to make direct comparison to the results from the K(N,Z)method of Ono et al.In our improved method,the extracted values of a_(sym)/T increase as the size of isotopes increases whereas,in the K(N,Z)method,the results show rather constant behavior.This increase in our result is attributed to the surface contribution of the symmetry energy in finite nuclei.In order to evaluate the surface contribution,the relation a_(sym)/T=[a_(sym)^((V))(1-k_(S/V) A^(-1/3))]/T is applied and k_(S/V)=1.20~1.25 was extracted.This value is smaller than those extracted from the mass table,reflecting the weakened surface contribution at higher temperature regime.Δμ/T,the difference of the neutron-proton chemical potentials relative to the temperature,is also extracted in this method at the same time.The average values of the extractedΔμ/T,Δμ/T show a linear dependence on the proton-neutron a_(sym)metry parameter of the system,δ_(sys),andΔμ/T=(15.1±0.2)δ_(sys)-(0.5±0.1)is obtained.展开更多
α-Trifluoromethyl ketones are a class of useful compounds with versatile applications.Their synthetic application via the transformation of the C—F bonds is of particular interest by allowing the synthesis of organi...α-Trifluoromethyl ketones are a class of useful compounds with versatile applications.Their synthetic application via the transformation of the C—F bonds is of particular interest by allowing the synthesis of organic compounds with diverse structures.Herein,the advances in the research areas ofα-trifluoromethyl ketone synthesis and their defluorination reactions are reviewed.Discussion on the mechanisms of the typical reactions has also been provided,in hope of affording some guides to the chemistry ofα-trifluoromethyl ketones in the synthetic methods toward themselves and their derivatives.展开更多
Efficient catalysis of the oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)is essential for the rechargeable zinc-air batteries(R-ZABs).However,challenges remain due to the scarcity of effective bifunc...Efficient catalysis of the oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)is essential for the rechargeable zinc-air batteries(R-ZABs).However,challenges remain due to the scarcity of effective bifunctional electrocatalysts and limited understanding of the structure-activity relationships.Pyrrole-type single-atom catalysts(SACs)with unique electronic structures have emerged as promising electrocatalysts.In this work,we combine density functional theory(DFT)calculations and experimental studies to systematically explore the structure-activity relationships and potential of pyrrole-type transition metal-N_(3)(TM-po-N_(3))as bifunctional catalysts.DFT calculations reveal that differences in the dependence of ORR and OER activities on the free energy of adsorption of reaction intermediates significantly affect the TM-po-N_(3)bifunctional activity and identify magnetic Cu-po-N_(3)as the best candidate.The bifunctional activity of Cu-po-N_(3)originates from interactions between spin-polarized out-of-plane Cu_3d and O_2s+2p orbitals.Theoretical predictions are validated experimentally,showing that the synthesized Cu-SAC/NC exhibits excellent bifunctional performance with a small potential gap of 0.666 V.Additionally,the assembled R-ZABs display a high-power density of 170 mW cm^(-2)and long-term stability,with the charge-discharge voltage gap increasing by only 0.01 V over 240 h.This work provides new insights into the design of efficient bifunctional catalysts.展开更多
Li-rich oxides are considered as promising candidate cathode materials for high-energy Li-ion batteries due to their high specific capacity.However,the widespread adoption of Li-rich materials is hindered because of t...Li-rich oxides are considered as promising candidate cathode materials for high-energy Li-ion batteries due to their high specific capacity.However,the widespread adoption of Li-rich materials is hindered because of the lack of a stable surface structure to inhibit interfacial side reactions.In this study,a stable LiF@spinel dual shell was constructed on the surface of Li-rich materials,in which spinel is formed by in situ surface recon-struction,and LiF is bonded to the spinel through the Ni–F bond.The spinel serves as a buffer layer between the LiF coating and the Li-rich oxide,providing a three-dimensional Li-ion diffusion channel to improve the Li-ion diffusion coefficient,while the outer LiF plays a critical role in isolating the cathode from the electrolyte.Under the abovementioned dual effect,the interfacial side reactions of Li-rich materials are inhibited,thereby improving their cycle stability.The obtained LiF@spinel-coated Li-rich cathode exhibits an enhanced capacity retention of 81.5%after 150 cycles at a current density of 2 C,which is better than the pristine Li-rich sample(63.2%).These findings indicate that the construction of the LiF@spinel dual shell is a successful strategy for the modification of Li-rich materials.展开更多
Three efficient methods for the synthesis of a series of Cu(Ⅱ) and Cu(Ⅰ) complexes based on imidazo[1,5-a]pyridine derivatives were developed.These methods include the following:(ⅰ)Cu(Ⅱ) salts were used as metal s...Three efficient methods for the synthesis of a series of Cu(Ⅱ) and Cu(Ⅰ) complexes based on imidazo[1,5-a]pyridine derivatives were developed.These methods include the following:(ⅰ)Cu(Ⅱ) salts were used as metal sources and N,N-dimethylformamide was employed as a solvent as well as a reductant to produce Cu(Ⅰ) complexes.(ⅱ) An iodide-containing compound was utilized as a ligand and iodide source to prepare complexes.An in situ metalligand reaction occurred and an iodide-bridged copper complex was generated.(ⅲ) A series of aldehydes were added to the reaction systems to induce in situ metal-ligand reactions between the aldehydes and the imidazo[1,5-a]pyridine derivatives,producing polydentate ligand scaffolds.Eight complexes were prepared and characterized.The catalytic activities of these complexes toward the ketalization of ketones by ethylene glycol were investigated.With the exception of complex4,the remaining seven complexes all showed high catalytic activity.The lower activity of 4 may be due to the larger radius of bridging iodide ions and the shorter Cu(Ⅰ)…Cu(Ⅰ) distance.CCDC:2357696,1·2CH_(2)Cl_(2);2357697,2;2018292,3;2092192,4;2092190,5;2155557,6;2406155,7;2406156,8·EtOH.展开更多
Management of groundwater resources and remediation of groundwater pollution require reliable quantification of contaminant dynamics in natural aquifers, which can involve complex chemical dynamics and challenge tradi...Management of groundwater resources and remediation of groundwater pollution require reliable quantification of contaminant dynamics in natural aquifers, which can involve complex chemical dynamics and challenge traditional modeling approaches. The kinetics of chemical reactions in groundwater are well known to be controlled by medium heterogeneity and reactant mixing, motivating the development of particle-based Lagrangian approaches. Previous Lagrangian solvers have been limited to fundamental bimolecular reactions in typically one-dimensional porous media. In contrast to other existing studies, this study developed a fully Lagrangian framework, which was used to simulate diffusion-controlled, multi-step reactions in one-, two-, and three-dimensional porous media. The interaction radius of a reactant molecule, which controls the probability of reaction, was derived by the agent-based approach for both irreversible and reversible reactions. A flexible particle tracking scheme was then developed to build trajectories for particles undergoing mixing-limited, multi-step reactions. The simulated particle dynamics were checked against the kinetics for diffusion-controlled reactions and thermodynamic wellmixed reactions in one-and two-dimensional domains. Applicability of the novel simulator was further tested by(1) simulating precipitation of calcium carbonate minerals in a two-dimensional medium, and(2) quantifying multi-step chemical reactions observed in the laboratory. The flexibility of the Lagrangian simulator allows further refinement to capture complex transport affecting chemical mixing and hence reactions.展开更多
Chiral carbonyl compounds frequently occur in natural products and pharmaceuticals. Additionally, they serve as important intermediates in organic synthesis. Transition metal-catalyzed asymmetric carbonylative cross-c...Chiral carbonyl compounds frequently occur in natural products and pharmaceuticals. Additionally, they serve as important intermediates in organic synthesis. Transition metal-catalyzed asymmetric carbonylative cross-coupling reactions are among the most straightforward and effective methods for synthesizing chiral carbonyl compounds, including esters, amides, and ketones. The advances in asymmetric carbonylative cross-coupling reactions using various O-, N-, C-, and S-containing nucleophiles or electrophiles over the past decade are summarized.展开更多
Paclitaxel is one of the commonly used drugs in postoperative chemotherapy for ovarian cancer patients. However, affected by drug dosage and individual differences in the course of medication, patients will have diffe...Paclitaxel is one of the commonly used drugs in postoperative chemotherapy for ovarian cancer patients. However, affected by drug dosage and individual differences in the course of medication, patients will have different degrees of adverse reactions, which will cause damage to the patient’s body once they occur. This paper retrospectively analyzed the clinical data of patients with severe allergic reactions such as fecal incontinence and numbness of hands and feet caused by the use of paclitaxel liposome during postoperative chemotherapy in a case of ovarian cancer admitted to our hospital. The causes and corresponding treatment measures were analyzed, in order to provide the reference for medical staff to take effective countermeasures in advance in the future.展开更多
Chiral quaternary phosphonium salts have recently been extensively developed as robust organic catalysts for asymmetric synthesis.Asymmetric addition reactions have been dominating in the chiral phosphonium salt-catal...Chiral quaternary phosphonium salts have recently been extensively developed as robust organic catalysts for asymmetric synthesis.Asymmetric addition reactions have been dominating in the chiral phosphonium salt-catalyzed construction of stereogenic carbon centers,heteroatom centers,axes and planes.The recent achievements in the chiral phosphonium-catalyzed asymmetric addition reactions are summarized.展开更多
基金Science and Technology Foundation of Guizhou Province(No.QKHJC-ZK[2024]654)Guizhou Provincial University Key Laboratory of Advanced Functional Electronic Materials(No.QJJ[2023]021).
文摘Carbenes as one of the most important class of intermediates have been widely utilized in various organic synthetic transformations.Carbene insertion-initiated ring-opening reactions of cyclic ethers offer a valuable strategy for constructing new carbon-oxygen bonds.In comparison with traditional thermal or metal-mediated carbene transfer reactions,visible-light-promoted multi-component reaction strategy provides a mild and eco-friendly approach to access densely functionalized molecules.Recently,visible-light-induced multi-component carbene transfer reactions of diazo compounds have been rapidly developed and attracted a great deal of research interest of chemists owing to their advantages of simple operation,mild condition,high atom economy and rich structural diversity.This paper summarizes the recent research progress on the visible-light-promoted multi-component carbene transfer reactions of diazo compounds via ring-opening of cyclic ethers with various nucleophiles.The reaction patterns of different nucleophiles and their corresponding mechanism are described in this review.The future research direction and challenges in this area are also discussed.
基金Funded by the National Natural Science Foundation of China Guangdong(No.22279096)。
文摘Silica nanoparticles-stabilized cobalt and nitrogen-doped carbon materials were synthesized through pyrolysis of metal-organic-framework of ZIF-67 supported by silica nanoparticles.The experimental results reveal that the introduction of the silica nanoparticles can stabilize the microstructure of the derived CoN-C materials,which in turn exhibits the promising electrocatalytic activity towards both oxygen reduction and oxygen evolution reactions.The optimized sample exhibits a better oxygen reduction activity than commercial Pt/C catalyst as confirmed by the positive shift of half-wave potential by 20 mV while it has a low overpotential of 273 mV for oxygen evolution reactions with the retained performance over 80%after 25,000 s of continuous operation.It is demonstrated that the introduction of support frame might be an effective way to improve the activity and stability of metal-organic-framework derived electrocatalyst with stabilized microstructure.
基金financially supported by the National Natural Science Foundation of China(Nos.52034002 and U2202254)the Fundamental Research Funds for the Central Universities,China(No.FRF-TT-19-001)。
文摘The sulfation and decomposition process has proven effective in selectively extracting lithium from lepidolite.It is essential to clarify the thermochemical behavior and kinetic parameters of decomposition reactions.Accordingly,comprehensive kinetic study by employing thermalgravimetric analysis at various heating rates was presented in this paper.Two main weight loss regions were observed during heating.The initial region corresponded to the dehydration of crystal water,whereas the subsequent region with overlapping peaks involved complex decomposition reactions.The overlapping peaks were separated into two individual reaction peaks and the activation energy of each peak was calculated using isoconversional kinetics methods.The activation energy of peak 1 exhibited a continual increase as the reaction conversion progressed,while that of peak 2 steadily decreased.The optimal kinetic models,identified as belonging to the random nucleation and subsequent growth category,provided valuable insights into the mechanism of the decomposition reactions.Furthermore,the adjustment factor was introduced to reconstruct the kinetic mechanism models,and the reconstructed models described the kinetic mechanism model more accurately for the decomposition reactions.This study enhanced the understanding of the thermochemical behavior and kinetic parameters of the lepidolite sulfation product decomposition reactions,further providing theoretical basis for promoting the selective extraction of lithium.
基金financially supported by National Natural Science Foundation of China(No.22302155)the Fundamental Research Funds of the Center Universities(No.D5000240188)the research program of ZJUT(YJY-ZS-20240001)。
文摘Metal halide perovskites(MHPs)with striking electrical and optical properties have appeared at the forefront of semiconductor materials for photocatalytic redox reactions but still suffer from some intrinsic drawbacks such as inferior stability,severe charge-carrier recombination,and limited active sites.Heterojunctions have recently been widely constructed to improve light absorption,passivate surface for enhanced stability,and promote charge-carrier dynamics of MHPs.However,little attention has been paid to the review of MHPs-based heterojunctions for photocatalytic redox reactions.Here,recent advances of MHPs-based heterojunctions for photocatalytic redox reactions are highlighted.The structure,synthesis,and photophysical properties of MHPs-based heterojunctions are first introduced,including basic principles,categories(such as Schottky junction,type-I,type-II,Z-scheme,and S-scheme junction),and synthesis strategies.MHPs-based heterojunctions for photocatalytic redox reactions are then reviewed in four categories:H2evolution,CO_(2)reduction,pollutant degradation,and organic synthesis.The challenges and prospects in solar-light-driven redox reactions with MHPs-based heterojunctions in the future are finally discussed.
基金the financial support from the Natural Science Foundation of Hunan Province,China(No.2022JJ40616)。
文摘The differences in the competitive reactions of hydrogarnet and quicklime when reacting with titaniumcontaining and silicon-containing minerals during the Bayer digestion process were investigated.Thermodynamic analysis,artificial mineral experiments,and an evaluation of the digestion effect of natural diasporic bauxite were conducted.The results indicate that hydrogarnet shows a preferential reaction with anatase,and this preference becomes more pronounced as the silicon saturation coefficient increases.In contrast,quicklime participates in non-selective reactions with both anatase and desilication products(DSP).The preference of hydrogarnet for anatase significantly enhances the utilization efficiency of CaO in the high-temperature Bayer digestion process.
文摘To develop specific lining materials for rare earth steel nozzles,LaAlO_(3)powder was first synthesized by high-temperature solid-phase synthesis at 1400℃for 3 h using La_(2)O_(3)and Al_(2)O_(3)powders as raw materials.Then BN,AlN,Si_(3)N_(4)and TiN powders were pressed intoφ30 mm×7 mm substrate samples under 120 MPa with PVA as the binder.Equal amounts of La_(2)O_(3)and LaAlO_(3)powders were placed on their surfaces,reacting at 1550℃for 3 h in different atmospheres(reducing and argon conditions).The interfacial reactions of the four nitride(BN,Si_(3)N_(4),AlN,and TiN)substrate samples with La_(2)O_(3)and LaAlO_(3)in different atmospheres were studied,respectively.The results show that in reducing and argon atmospheres,the intensity order of the reactions between the four nitrides and La_(2)O_(3)is Si_(3)N_(4)>BN>AlN>TiN.In the reducing atmosphere,the reaction intensity order of the four nitrides with LaAlO_(3)is Si_(3)N_(4)>AlN≈TiN>BN.However,in the argon atmosphere,the order is Si_(3)N_(4)>BN>AlN≈TiN.TiN has good structural stability in both reducing and argon atmospheres,and shows weak reactivity with La_(2)O_(3)and LaAlO_(3).It is a relatively good anti-clogging lining material for rare earth steel nozzles.
基金supported by the National Natural Science Foundation of China(Nos.92461313 and 22121002)the National Key R&D Program of China(No.2021YFA1500704).
文摘Organometallics play a vital role in catalytic and synthetic processes.Understanding the indi-vidual elementary steps of the reactions of organo metallic com-pounds is crucial for the development and ratio-nal design of new organometallic reagents and catalysts.Study of gas-phase reactions is one of the key approaches to probing the individual elementary steps under isolated and re-producible conditions.A series of investigations have been reported on the gas-phase reac-tions between organometallic ions and neutral molecules under room temperature conditions.However,studies about the reactions between organometallic ions and neutral molecules un-der heating conditions are very limited.In this work,an apparatus with an electrospray ion-ization source and an ion funnel trap,which can be coupled with a high-temperature linear ion trap reactor,was designed and built.The apparatus can be used to investigate the reac-tions between organometallic ions and neutral molecules under heating conditions.By using the apparatus,the adsorption reactions of Rh(PPh_(3))_(2)^(+)+CO→Rh(PPh_(3))_(2)CO^(+)and CuPPh_(3)^(+)+CO_(2)→CuPPh_(3)CO_(2)+under variable temperature conditions have been conducted.The experiments showed that the reaction rate constant of Rh(PPh_(3))_(2)^(+)+CO increases first and then decreases with increasing temperature.In contrast,the rate constant of CuPPh_(3)^(+)+CO_(2)decreases monotonically as the temperature increases.Density functional theory calculations indicate that the adsorption reaction of Rh(PPh_(3))_(2)^(+)+CO→Rh(PPh_(3))_(2)CO^(+)is subject to a small barrier,while CuPPh_(3)^(+)+CO_(2)→CuPPh_(3)CO_(2)+is barri-erless,which is consistent with the experimentally observed temperature-dependent rate con-stants.The newly built apparatus can thus provide new kinetic information to address reac-tion mechanisms for organometallic ions.
基金support from the National Key Research and Development Program of China(No.2023YFA0914100/2023YFA0914102)the National Natural Science Foundation of China(Nos.22077029 and 22034002)+2 种基金the Science Fund for Distinguished Young Scholars of Hunan Province(No.2021JJ10034)support from the National Natural Science Foundation of China(No.22276049)M.M.acknowledge the support from the National Natural Science Foundation of China(No.22276050).
文摘We report for the first time the combination of directed evolution focused on enhancing and reversing the stereoselectivity of an enzyme with Cu(I)-mediated click chemistry(CuAAC),providing an asymmetric click approach for versatile chiral triazoles products.In this study,the halohydrin dehalogenase HheG was used as the enzyme which was evolved to induce a stereoselective ring-opening reaction of cyclic epoxides in the presence of NaN3 with the formation of chiral azido products.Two mutants of opposite stereopreference were generated,which convert cyclohexene oxide as well as cycloheptene oxide to(1S,2S)-2-azidocyclohexanol,(1R,2R)-2-azidocyclohexanol,(1S,2S)-2-azidocycloheptanol and(1R,2R)-2-azidocycloheptanol with essentially high stereoselectivity.The chiral products were then subjected to CuAAC in reactions with structurally different alkynes.Since HheG was found to be compatible with Cu(I),the process was also performed successfully in a unique 2-step one-pot process leading to various chiral triazoles.In order to understand the enhancement and reversal of the evolved enantioselectivity,QM and MD computations were performed.This approach harnesses the modifiability and high stereoselectivity of the evolved biocatalysts in combination with click chemistry.It holds great potential for diverse fields,particularly in the area of pharmaceuticals.
基金conducted under the public contract for the Tomsk Scientific Center of the Siberian Branch of the Russian Academy of Sciences(Project No.FWRF-2024-0009).
文摘This study presents an investigation into shock-induced exothermic reactions within three distinct aluminum-based energetic mixtures:aluminum/sulfur(Al/S),aluminum/copper oxide(Al/CuO),and aluminum/polytetrafluoroethylene(Al/PTFE).A challenge in current modeling efforts is accurately capturing the complex physical and chemical coupling under extreme loading,especially the influence of rapidly forming gaseous products in Al/PTFE mixtures on material integrity.To address this,a wide-range numerical model based on the Smoothed Particle Hydrodynamics(SPH)method was developed.This mesh-free approach manages large deformations and incorporates elastic-plastic flow,heat transfer,component diffusion,and chemical kinetics simulated using both zero-and first-order reaction schemes,favoring the latter for surface-reaction mechanisms.The proposed model takes into account gaseous reaction products,specifically aluminum fluoride(AlF3)to assess their impact on ampoule fracture dynamics.Numerical simulations,validated against experimental data,demonstrated that reaction rate,local pressure,and temperature are the primary controlling factors governing energy release and structural response.Comparative analysis revealed that although Al/CuO initiates reaction more readily(lower critical pressure/temperature),the Al/S mixture exhibits superior overall reaction efficiency under shock-wave loading,highlighting the significance of post-initiation kinetic factors.Furthermore,simulations using the conical ampoule geometry confirmed its effectiveness in generating a continuous pressure gradient,enabling systematic characterization of pressure-dependent reaction kinetics.This validated SPH model provides a powerful and predictive tool for understanding the complex behavior of energetic materials under shock-wave loading and aids in optimizing material composition for desired performance characteristics.
基金supported by the National Key Research and Development program(2022YFA1504000)the National Natural Science Foundation of China(22302101)+4 种基金the Fundamental Research Funds for the Central Universities(63185015)the Shenzhen Science and Technology Program(JCYJ20210324121002007,JCYJ20230807151503007)the Yunnan Provincial Science and Technology Project at Southwest United Graduate School(202402AO370001)the China Postdoctoral Science Foundation(2022M721699)the Guangdong Basic and Applied Basic Research Foundation(2024A1515010347).
文摘During the oxygen evolution reaction(OER),reconstruction of transition metal sulfides(TMSs)is inevitable.However,the lack of a clear theoretical understanding of this process has impeded the development of effective reconstruction regulation strategies.In this study,we first explored the reconstruction mechanism of CoS_(2)during OER from the perspective of electronic structure and identified two possible pathways:the OH-assisted mechanism and the O-assisted mechanism.Further verification showed that these mechanisms are universally applicable to other TMSs(e.g.,FeS_(2)).Based on the reconstruction mechanism,we investigated the basic reasons for the influence of various regulation strategies,such as vacancy modification and facet engineering,on the reconstruction ability.This verified that the method of analyzing the change in the reconstruction ability of catalysts based on the reconstruction mechanism has a high degree of applicability.Importantly,we proposed a core regulation strategy:the coordination symmetry regulation strategy.Specifically,by breaking the symmetry of the surface coordination environment of TMSs(such as introducing heteroatom doping or strain),the reconstruction process will be facilitated.Our findings provide a comprehensive mechanistic explanation for the reconstruction of TMS catalysts and offer a new idea for the rational design of OER catalysts with controllable reconstruction capacity.
基金supported by the National Natural Sci-ence Foundation of China(Nos.22233004,22003062)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB0970000).
文摘Controversies and arguments about the origin of plan-etary water have aroused enthusiasm to search for possible chemical sources.Considering the CO_(2)-rich atmospheres of Mars,Venus,and the prebiotic Earth,we propose that chemical reactions between HOCO^(+)and H_(2)can contribute to the production of H_(2)O on the basis of high-level calculations.As for the reagents,HOCO^(+)can form via the protonation of CO_(2),while H+and H_(2)are from the solar wind or in-terstellar space.Note that one of the reaction path-ways undergoes multiple transition-state complexes and exhibits the roaming-like dynamics feature.More-over,intermolecular proton or hydrogen transfer is a key step in the production of H_(2)O,there-by H-tunneling effect profoundly enhances the reaction rate in a wide range of temperatures or collision energies.
文摘An improved method is proposed for the extraction of the symmetry energy coefficient relative to the temperature,a_(sym)/T,in the heavy-ion reactions near the Fermi energy region,based on the modified Fisher Model.This method is applied to the primary fragments of antisymmetrized molecular dynamics(AMD)simulations for ^(46)Fe+^(46)Fe,^(40)Ca+^(40)Ca and ^(48)Ca+^(48)Ca at 35 MeV/nucleon,in order to make direct comparison to the results from the K(N,Z)method of Ono et al.In our improved method,the extracted values of a_(sym)/T increase as the size of isotopes increases whereas,in the K(N,Z)method,the results show rather constant behavior.This increase in our result is attributed to the surface contribution of the symmetry energy in finite nuclei.In order to evaluate the surface contribution,the relation a_(sym)/T=[a_(sym)^((V))(1-k_(S/V) A^(-1/3))]/T is applied and k_(S/V)=1.20~1.25 was extracted.This value is smaller than those extracted from the mass table,reflecting the weakened surface contribution at higher temperature regime.Δμ/T,the difference of the neutron-proton chemical potentials relative to the temperature,is also extracted in this method at the same time.The average values of the extractedΔμ/T,Δμ/T show a linear dependence on the proton-neutron a_(sym)metry parameter of the system,δ_(sys),andΔμ/T=(15.1±0.2)δ_(sys)-(0.5±0.1)is obtained.
文摘α-Trifluoromethyl ketones are a class of useful compounds with versatile applications.Their synthetic application via the transformation of the C—F bonds is of particular interest by allowing the synthesis of organic compounds with diverse structures.Herein,the advances in the research areas ofα-trifluoromethyl ketone synthesis and their defluorination reactions are reviewed.Discussion on the mechanisms of the typical reactions has also been provided,in hope of affording some guides to the chemistry ofα-trifluoromethyl ketones in the synthetic methods toward themselves and their derivatives.
基金supported by the Hainan Province Science and Technology Special Fund(ZDYF2020037)the National Natural Science Foundation of China(22109035,52164028,52274297,22462006)+3 种基金the Postdoctoral Science Foundation of Hainan Province(RZ2100007123)the Basic and Applied Basic Research Foundation of Guangdong Province(2019A1515110558)the Start-up Research Foundation of Hainan University(KYQD(ZR)-20008,20083,20084,21125)Hainan University(XTCX2022HYC05)。
文摘Efficient catalysis of the oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)is essential for the rechargeable zinc-air batteries(R-ZABs).However,challenges remain due to the scarcity of effective bifunctional electrocatalysts and limited understanding of the structure-activity relationships.Pyrrole-type single-atom catalysts(SACs)with unique electronic structures have emerged as promising electrocatalysts.In this work,we combine density functional theory(DFT)calculations and experimental studies to systematically explore the structure-activity relationships and potential of pyrrole-type transition metal-N_(3)(TM-po-N_(3))as bifunctional catalysts.DFT calculations reveal that differences in the dependence of ORR and OER activities on the free energy of adsorption of reaction intermediates significantly affect the TM-po-N_(3)bifunctional activity and identify magnetic Cu-po-N_(3)as the best candidate.The bifunctional activity of Cu-po-N_(3)originates from interactions between spin-polarized out-of-plane Cu_3d and O_2s+2p orbitals.Theoretical predictions are validated experimentally,showing that the synthesized Cu-SAC/NC exhibits excellent bifunctional performance with a small potential gap of 0.666 V.Additionally,the assembled R-ZABs display a high-power density of 170 mW cm^(-2)and long-term stability,with the charge-discharge voltage gap increasing by only 0.01 V over 240 h.This work provides new insights into the design of efficient bifunctional catalysts.
基金funded by Science Research Project of Hebei Education Department(Grant No.ZD2022042)the Interdisciplinary Research Program of Hebei University(Grant No.DXK202315)+2 种基金the National Natural Science Foundation of China(NSFC)(Grant Nos.52104304 and 51902081)Central Government Guided Local Science and Technology Development Project of Hebei Province(Grant No.246Z4409G)the Scientific Research and Innovation Team of Hebei University(Grant No.IT2023B07).
文摘Li-rich oxides are considered as promising candidate cathode materials for high-energy Li-ion batteries due to their high specific capacity.However,the widespread adoption of Li-rich materials is hindered because of the lack of a stable surface structure to inhibit interfacial side reactions.In this study,a stable LiF@spinel dual shell was constructed on the surface of Li-rich materials,in which spinel is formed by in situ surface recon-struction,and LiF is bonded to the spinel through the Ni–F bond.The spinel serves as a buffer layer between the LiF coating and the Li-rich oxide,providing a three-dimensional Li-ion diffusion channel to improve the Li-ion diffusion coefficient,while the outer LiF plays a critical role in isolating the cathode from the electrolyte.Under the abovementioned dual effect,the interfacial side reactions of Li-rich materials are inhibited,thereby improving their cycle stability.The obtained LiF@spinel-coated Li-rich cathode exhibits an enhanced capacity retention of 81.5%after 150 cycles at a current density of 2 C,which is better than the pristine Li-rich sample(63.2%).These findings indicate that the construction of the LiF@spinel dual shell is a successful strategy for the modification of Li-rich materials.
文摘Three efficient methods for the synthesis of a series of Cu(Ⅱ) and Cu(Ⅰ) complexes based on imidazo[1,5-a]pyridine derivatives were developed.These methods include the following:(ⅰ)Cu(Ⅱ) salts were used as metal sources and N,N-dimethylformamide was employed as a solvent as well as a reductant to produce Cu(Ⅰ) complexes.(ⅱ) An iodide-containing compound was utilized as a ligand and iodide source to prepare complexes.An in situ metalligand reaction occurred and an iodide-bridged copper complex was generated.(ⅲ) A series of aldehydes were added to the reaction systems to induce in situ metal-ligand reactions between the aldehydes and the imidazo[1,5-a]pyridine derivatives,producing polydentate ligand scaffolds.Eight complexes were prepared and characterized.The catalytic activities of these complexes toward the ketalization of ketones by ethylene glycol were investigated.With the exception of complex4,the remaining seven complexes all showed high catalytic activity.The lower activity of 4 may be due to the larger radius of bridging iodide ions and the shorter Cu(Ⅰ)…Cu(Ⅰ) distance.CCDC:2357696,1·2CH_(2)Cl_(2);2357697,2;2018292,3;2092192,4;2092190,5;2155557,6;2406155,7;2406156,8·EtOH.
基金supported by the National Natural Science Foundation of China(Grants No.41330632,41628202,and 11572112)
文摘Management of groundwater resources and remediation of groundwater pollution require reliable quantification of contaminant dynamics in natural aquifers, which can involve complex chemical dynamics and challenge traditional modeling approaches. The kinetics of chemical reactions in groundwater are well known to be controlled by medium heterogeneity and reactant mixing, motivating the development of particle-based Lagrangian approaches. Previous Lagrangian solvers have been limited to fundamental bimolecular reactions in typically one-dimensional porous media. In contrast to other existing studies, this study developed a fully Lagrangian framework, which was used to simulate diffusion-controlled, multi-step reactions in one-, two-, and three-dimensional porous media. The interaction radius of a reactant molecule, which controls the probability of reaction, was derived by the agent-based approach for both irreversible and reversible reactions. A flexible particle tracking scheme was then developed to build trajectories for particles undergoing mixing-limited, multi-step reactions. The simulated particle dynamics were checked against the kinetics for diffusion-controlled reactions and thermodynamic wellmixed reactions in one-and two-dimensional domains. Applicability of the novel simulator was further tested by(1) simulating precipitation of calcium carbonate minerals in a two-dimensional medium, and(2) quantifying multi-step chemical reactions observed in the laboratory. The flexibility of the Lagrangian simulator allows further refinement to capture complex transport affecting chemical mixing and hence reactions.
文摘Chiral carbonyl compounds frequently occur in natural products and pharmaceuticals. Additionally, they serve as important intermediates in organic synthesis. Transition metal-catalyzed asymmetric carbonylative cross-coupling reactions are among the most straightforward and effective methods for synthesizing chiral carbonyl compounds, including esters, amides, and ketones. The advances in asymmetric carbonylative cross-coupling reactions using various O-, N-, C-, and S-containing nucleophiles or electrophiles over the past decade are summarized.
文摘Paclitaxel is one of the commonly used drugs in postoperative chemotherapy for ovarian cancer patients. However, affected by drug dosage and individual differences in the course of medication, patients will have different degrees of adverse reactions, which will cause damage to the patient’s body once they occur. This paper retrospectively analyzed the clinical data of patients with severe allergic reactions such as fecal incontinence and numbness of hands and feet caused by the use of paclitaxel liposome during postoperative chemotherapy in a case of ovarian cancer admitted to our hospital. The causes and corresponding treatment measures were analyzed, in order to provide the reference for medical staff to take effective countermeasures in advance in the future.
文摘Chiral quaternary phosphonium salts have recently been extensively developed as robust organic catalysts for asymmetric synthesis.Asymmetric addition reactions have been dominating in the chiral phosphonium salt-catalyzed construction of stereogenic carbon centers,heteroatom centers,axes and planes.The recent achievements in the chiral phosphonium-catalyzed asymmetric addition reactions are summarized.
