Extensive experimental studies have been performed on the Diels-Alder(DA)reactions in ionic liquids(ILs),which demonstrate that the IL environment can significantly influence the reaction rates and selectivity.However...Extensive experimental studies have been performed on the Diels-Alder(DA)reactions in ionic liquids(ILs),which demonstrate that the IL environment can significantly influence the reaction rates and selectivity.However,the underlying microscopic mechanism remains ambiguous.In this work,the multiscale reaction density functional theory is applied to explore the effect of 1-butyl-3-methylimidazolium hexafluorophosphate([BMIM][PF_(6)])solvent on the reaction of cyclopentadiene(CP)with acrolein,methyl acrylate,or acrylonitrile.By analyzing the free energy landscape during the reaction,it is found that the polarization effect has a relatively small influence,while the solvation effect makes both the activation free energy and reaction free energy decrease.In addition,the rearrangement of local solvent structure shows that the cation spatial distribution responds more evidently to the reaction than the anion,and this indicates that the cation plays a dominant role in the solvation effect and so as to affect the reaction rates and selectivity of the DA reactions.展开更多
Lithium metal anodes are of great interest for advanced high-energy density batteries such as lithiumair, lithium-sulfur and solid-state batteries, due to their low electrode potential and ultra-high theoretical capac...Lithium metal anodes are of great interest for advanced high-energy density batteries such as lithiumair, lithium-sulfur and solid-state batteries, due to their low electrode potential and ultra-high theoretical capacity. There are, however, several challenges limiting their practical applications, which include low coulombic efficiency, the uncontrollable growth of dendrites and poor rate capability. Here, a rational design of 3D structured lithium metal anodes comprising of in-situ growth of cobalt-decorated nitrogen-doped carbon nanotubes on continuous carbon nanofibers is demonstrated via electrospinning.The porous and free-standing scaffold can enhance the tolerance to stresses resulting from the intrinsic volume change during Li plating/stripping, delivering a significant boost in both charge/discharge rates and stable cycling performance. A binary Co-Li alloying phase was generated at the initial discharge process, creating more active sites for the Li nucleation and uniform deposition. Characterization and density functional theory calculations show that the conductive and uniformly distributed cobalt-decorated carbon nanotubes with hierarchical structure can effectively reduce the local current density and more easily absorb Li atoms, leading to more uniform Li nucleation during plating. The current work presents an advance on scalable and cost-effective strategies for novel electrode materials with 3D hierarchical microstructures and mechanical flexibility for lithium metal anodes.展开更多
Here we report a strategy to enhance the energy density of supercapacitors by increasing the utilization rate of the specific surface area(SSA)via wettability improvement. The nonporous gold(NPG) film is used as the e...Here we report a strategy to enhance the energy density of supercapacitors by increasing the utilization rate of the specific surface area(SSA)via wettability improvement. The nonporous gold(NPG) film is used as the electrodes and the ionic liquid [EMIM]BF4 is the electrolyte. When the electrode is coated by paraffin, an increase of the contact angle leads to a remarkable reduction of the specific capacitance. While when acetonitrile is added into the electrolyte, the contact angle is decreased and the utilization rate of SSA is improved, which results in an increase of the specific capacitance. The addition of isopropyl acetate into the electrolyte leads to a further increase of the specific capacitance. To generalize the role of the wettability in improving the energy density, a carbon-based electrode is evaluated in the solution of potassium hydroxide. An addition of propyl alcohol into the potassium hydroxide solution leads to an increase of the specific capacitance, as well as a long-term stability of the supercapacitor. The role of conductivity in this study is excluded by designing experiments. This paper highlights the significance of wettability in determining the specific capacitance, showing an alternative to improve the energy density of supercapacitors.展开更多
Whereas the proper choice of reaction solvent constitutes the cornerstone of the green solvent concept,solvent effects on chemical reactions are not mechanistically well understood due to the lack of feasible molecula...Whereas the proper choice of reaction solvent constitutes the cornerstone of the green solvent concept,solvent effects on chemical reactions are not mechanistically well understood due to the lack of feasible molecular models.Herein,by taking the case study of nucleophilic addition reaction in aqueous solution,we extend the proposed multiscale reaction density functional theory(RxDFT)method to investigate the intrinsic free energy profile and total free energy profile,and study the solvent effect on the activation and reaction free energy for the nucleophilic addition reactions of hydroxide anion with methanal and carbon dioxide in aqueous solution.The predictions of the free energy profile in aqueous solution for these two nucleophilic addition reactions from RxDFT have a satisfactory agreement with the results from the RISM and MD-FEP simulation.Meanwhile,the solvent effect is successfully addressed by examining the difference of the free energy profile between the gas phase and aqueous phase.In addition,we investigate the solvent effect on the reactions occurred near solid-liquid interfaces.It is shown that the activation free energy is significantly depressed when reaction takes place in the region within 10A distance to the substrate surface owing to the decrease of hydration free energy at the solid-liquid interface.展开更多
Whereas theπ-πstacking interactions at oil/water interfaces can affect interfacial structures hence the interfacial properties,the underlying microscopic mechanism remains largely unknown.We reported an all-atom mol...Whereas theπ-πstacking interactions at oil/water interfaces can affect interfacial structures hence the interfacial properties,the underlying microscopic mechanism remains largely unknown.We reported an all-atom molecular dynamics(MD)simulation study to demonstrate how the Gemini surfactants with pyrenyl groups affect the interracial properties,structural conformations,and the motion of molecules in the water/n-octane/surfactant ternary systems.It is found that the pyrenyl groups tend to be vertical to the interface owing to theπ-πstacking interaction.Besides,a synergistic effect between theπ-πinteraction and steric hindrance is found,which jointly affects the coalescence of liquid droplets.Therefore,the existence of aromatic groups and a moderate number of surfactants helps to form microemulsion.This work provides a molecular understanding of Gemini surfactants with aromatic groups in microemulsion preparation and applications.展开更多
The dehydration of water by dimethyl carbonate(DMC)is of great significance for its application in electrochemistry and oil industry.With the rapid development of nanomaterial,one-dimensional(e.g.carbon nanotube(CNT))...The dehydration of water by dimethyl carbonate(DMC)is of great significance for its application in electrochemistry and oil industry.With the rapid development of nanomaterial,one-dimensional(e.g.carbon nanotube(CNT))and two-dimensional(e.g.lamellar graphene)materials have been widely used for molecular sieving.In this work,the molecular behavior of dimethyl carbonate/water mixture confined in CNT with varying diameters was studied based on molecular dynamics simulation.Due to different van der Waals interactions for the components in the mixtures with the solid surface,DMC molecules are preferentially adsorbed on the inner surface of the pore wall and formed an adsorption layer.Comparing with the pure water molecules confined in CNT,the adsorption DMC layer shows notable effect on the local compositions and microstructures of water molecules under nanoconfinement,which may result in different water mobility.Our analysis shows that the surface-induced DMC molecules can destroy the hydrogen bonding network of water molecules and result in an uniform and dispersed distribution of water molecules in the tube.These clear molecular understandings can be useful in material design for membrane separation.展开更多
It is important to study the solvent effect on keto-enol tautomerism that has applications in many areas of chemical engineering.In this work,we use a multiscale reaction density functional theory(Rx DFT)to study the ...It is important to study the solvent effect on keto-enol tautomerism that has applications in many areas of chemical engineering.In this work,we use a multiscale reaction density functional theory(Rx DFT)to study the keto-enol tautomerism and isomerization of pyruvic acid.The results show that both effects of solvation and water assistance could reduce the reaction barriers.The water molecule participates the reaction as a catalyst to accept/give the protons with forming a hexagonal ring in the transition state.As a result of this temporary and intermediate hexagonal ring,the solute configuration undergoes a small variation during the reaction,giving a diminished contribution to the intrinsic reaction free energy.The solvent distribution shows a local ordering behavior near the solute that also reduces the contribution of solvation effect to the reaction barrier.Water assistance plays a major role in both pre-reaction and postreaction process.In terms of the driving force for the reaction,the effects of both solvation and water assistance are important.展开更多
Crystal habit and crystal form are critical elements in determining product properties and functions. In this work, we developed a microfluidic antisolvent crystallization technique to rapidly screen and accurately co...Crystal habit and crystal form are critical elements in determining product properties and functions. In this work, we developed a microfluidic antisolvent crystallization technique to rapidly screen and accurately control the solid form and crystal habit of triphenylmethanol(Ph_(3)COH). This advanced technique separates the primary mixing of solutions from crystal formation(nucleation and growth) by introducing the microfluidic device, avoiding clogging in microchannels to obtain high-quality crystals. The results show that we can achieve controllable preparation of pure 2Ph_(3)COH·DMSO(DMSO solvate), pure Ph_(3)COH(form β), and mixed crystals with different mass ratios. Moreover, the microscale can prompt the DMSO solvate to grow into hexagonal sheet-like and bulk crystals. We can regulate the aspect ratio of hexagonal sheet-like crystals in binary solvents and control the crystal habit of the form β to transition between long needle-like shapes and short hexagonal prisms in DMF-H_(2)O. Meanwhile, we revealed that the solvent ratio, the antisolvent flow rate, and the initial concentration of Ph_(3)COH are the main factors affecting the solid form selectivity and morphology transition. Such a novel method would be considered as a promising technique to be extended to screen and control key crystallization parameters of other substances.展开更多
In this work, a liquid-gas heterogeneous microreactor was developed for investigating continuous crystallization of dolutegravir sodium(DTG), as well as revealing reaction kinetics and mixing mechanism with 3-min data...In this work, a liquid-gas heterogeneous microreactor was developed for investigating continuous crystallization of dolutegravir sodium(DTG), as well as revealing reaction kinetics and mixing mechanism with 3-min data acquisition. The reaction kinetics models were established by visually recording the concentration variation of reactants over time in the microchannel via adding pH-sensitive fluorescent dye. The mixing intensification mechanism of liquid-gas flow was quantified through the fluorescent signal to indicate mixing process, demonstrating an outstanding mixing performance with a mixing time less than 0.1 s. Compared with batch crystallization, continuous synthesis of dolutegravir sodium using liquid-gas heterogenous microreactor optimizes crystal distribution size, and successfully modifies the crystal morphology in needle-like habit instead of rod-like habit. The microreactor continuous crystallization can run for 5 h without crystal blockage and achieve D90 of DTG less than 30 μm. This work provides a feasible approach for continuously synthesizing dolutegravir sodium, and can optimize the existing pharmaceutical crystallization.展开更多
A catalytic micro-reactor for converting hydrogen off-gas into water was recently developed, through which the conversion efficiency of hydrogen gas was greatly improved by hydrophobic modification of the catalytic su...A catalytic micro-reactor for converting hydrogen off-gas into water was recently developed, through which the conversion efficiency of hydrogen gas was greatly improved by hydrophobic modification of the catalytic substrate. Herein, a hybrid theoretical method is reported that combines density functional theory (DFT) on both the quantum and molecular scales. This method allows the microscopic study of the mechanism by which the surface catalytic reaction can be manipulated. Specifically, quantum DFT calculations are performed to quantify the molecular interaction between the catalytic substrate and reagent or product. Classical DFT investigations are subsequently carried out to determine the local concentrations of reagents near catalytic sites subject to different surface coating conditions. Finally, the reaction efficiency is determined from the local concentrations based on collision theory. This multiscale method provides molecular insight for quantifying the effect of catalytic surface modification on the reaction efficiency. The method reveals that an optimal surface hydrophobic modification can promote the densities of reagents near the substrate, while depleting the produced water. These two factors promote the conversion efficiency. The exclusion of produced water from the catalytic substrate is affected more by the degree of polymer grafting than by the chain length of hydrophobic polymer moieties.展开更多
Electrochemical nitrogen reduction reaction(eNRR)is one of the most important chemical reactions for the production of ammonia under ambient environment.However,the lack of in-depth understanding of the structure-acti...Electrochemical nitrogen reduction reaction(eNRR)is one of the most important chemical reactions for the production of ammonia under ambient environment.However,the lack of in-depth understanding of the structure-activity relationship impedes the development of high-performance catalysts for ammonia production.Herein,the density functional theory(DFT)calculations are performed to reveal the structure–activity relationship for the single-atom catalysts(SACs)supported on g-C_(3)N_(4),which is modified by molecular groups(i.e.,H,O,and OH).The computational results demonstrate that the W-based SACs are beneficial to produce ammonia with a low limiting potential(UL).Particularly,the W-OH@g-C_(3)N_(4) catalyst exhibits an ultralow UL of−0.22 V for eNRR.And the competitive eNRR selectivity can be identified by the dominant*N2 adsorption free energy than that of*H.Our findings provide a theoretical basis for the synthesis of efficient catalysts to produce ammonia.展开更多
Three new porphyrin dyes XW45-XW47 have been synthesized employing a dialkoxy-wrapped phenothiazine donor, a tetraalkoxy-wrapped porphyrin π-framework, a benzothiadiazole(BTD)-based auxiliary acceptor, and an anchori...Three new porphyrin dyes XW45-XW47 have been synthesized employing a dialkoxy-wrapped phenothiazine donor, a tetraalkoxy-wrapped porphyrin π-framework, a benzothiadiazole(BTD)-based auxiliary acceptor, and an anchoring benzoic acid group. On the basis of our previously reported dye XW36, XW45 was synthesized by introducing a BTD unit to broaden the absorption spectrum, further introducing a hexyl-substituent into the BTD unit afforded XW46, and an additional fluorine atom was introduced to the carboxyphenyl acceptor to afford XW47. As expected, the BTD unit obviously broadens and red-shifts the absorption threshold of XW45-XW47 to ca.750 nm. Dye-sensitized solar cells(DSSCs) were fabricated based on a cobalt electrolyte using chenodeoxycholic acid(CDCA) as the coadsorbent. Under full sun illumination, XW45 exhibits an efficiency of 9.73%, which is slightly lower than that of 10.19% obtained for the reference dye SM315. By contrast, XW46 and XW47 show higher efficiencies than SM315 owing to the improved anti-aggregation ability associated with the hexyl group on the BTD unit and better ICT effect induced by the fluorine atom on the carboxyphenyl unit. Thus, XW47 exhibits the highest efficiency of 10.41% among the porphyrin dyes. Furthermore, PT-C6 was used as the cosensitizer to improve the light harvesting ability and efficiencies of the cells due to its broad absorption within 350–560 nm. Thus, high efficiencies of 10.32%, 11.38% and 10.90% were achieved for the cosensitized solar cells based on XW45–XW47, respectively, owing to the obviously enhanced photocurrent density(JSC). In addition, under 30% full sun illumination, XW46+PT-C6 exhibits a high efficiency of 13.08%. These results give an effective method for building high performance DSSCs through the cosensitization of porphyrin dyes containing a wrapped donor, a wrapped porphyrin framework and a properly substituted auxiliary benzothiadiazole unit.展开更多
Two fluorescence "turn-on" Zn^(2+) probes were developed by introducing an anthracenyl fluorophore through the linkage of a diphenylamino moiety at the 5-position of a dipyrrin moiety.Thus,two compounds with...Two fluorescence "turn-on" Zn^(2+) probes were developed by introducing an anthracenyl fluorophore through the linkage of a diphenylamino moiety at the 5-position of a dipyrrin moiety.Thus,two compounds with weak fluorescence were designed,synthesized,and employed as CHEF(chelation enhanced fluorescence) type fluorescence "turn-on" Zn^(2+) probes,which exhibit dramatic fluorescence enhancement upon addition of Zn^(2+),showing high sensitivities and impressive detection limits of 13 and12 nM,respectively,better than their analogues containing simple aryl substituents at the 5 positions of a di-or tripyrrin moiety.In addition,both of the probes exhibit good selectivity,short response time of less than 10 s and wide applicable pH ranges.Furthermore,the weak fluorescence nature of the probes was rationalized based on viscosity dependence measurements and theoretical calculations.These results provide further insight into the development of selective and sensitive zinc probes.展开更多
基金supported by the National Natural Science Foundation of China(22168002,22108070,21878078)the Natural Science Foundation of Guangxi Province(2020GXNSFAA159119)+2 种基金the Dean Project of Guangxi Key Laboratory of Petrochemical Resource Processing and Process Intensification Technology(2021Z012)the Open Fund of the State Key Laboratory of Molecular Reaction Dynamics in DICP(SKLMRD-K202106)the Young Elite Scientists Sponsorship Program by CAST(2022QNRC001)。
文摘Extensive experimental studies have been performed on the Diels-Alder(DA)reactions in ionic liquids(ILs),which demonstrate that the IL environment can significantly influence the reaction rates and selectivity.However,the underlying microscopic mechanism remains ambiguous.In this work,the multiscale reaction density functional theory is applied to explore the effect of 1-butyl-3-methylimidazolium hexafluorophosphate([BMIM][PF_(6)])solvent on the reaction of cyclopentadiene(CP)with acrolein,methyl acrylate,or acrylonitrile.By analyzing the free energy landscape during the reaction,it is found that the polarization effect has a relatively small influence,while the solvation effect makes both the activation free energy and reaction free energy decrease.In addition,the rearrangement of local solvent structure shows that the cation spatial distribution responds more evidently to the reaction than the anion,and this indicates that the cation plays a dominant role in the solvation effect and so as to affect the reaction rates and selectivity of the DA reactions.
基金kindly supported by the National Natural Science Foundation of China (No. U1864213)the EPSRC Joint UK-India Clean Energy center (JUICE) (EP/P003605/1)+2 种基金the EPSRC Multi-Scale Modelling project (EP/S003053/1)the Innovate UK for Advanced Battery Lifetime Extension (ABLE) projectthe EPSRC for funding under EP/S000933/1。
文摘Lithium metal anodes are of great interest for advanced high-energy density batteries such as lithiumair, lithium-sulfur and solid-state batteries, due to their low electrode potential and ultra-high theoretical capacity. There are, however, several challenges limiting their practical applications, which include low coulombic efficiency, the uncontrollable growth of dendrites and poor rate capability. Here, a rational design of 3D structured lithium metal anodes comprising of in-situ growth of cobalt-decorated nitrogen-doped carbon nanotubes on continuous carbon nanofibers is demonstrated via electrospinning.The porous and free-standing scaffold can enhance the tolerance to stresses resulting from the intrinsic volume change during Li plating/stripping, delivering a significant boost in both charge/discharge rates and stable cycling performance. A binary Co-Li alloying phase was generated at the initial discharge process, creating more active sites for the Li nucleation and uniform deposition. Characterization and density functional theory calculations show that the conductive and uniformly distributed cobalt-decorated carbon nanotubes with hierarchical structure can effectively reduce the local current density and more easily absorb Li atoms, leading to more uniform Li nucleation during plating. The current work presents an advance on scalable and cost-effective strategies for novel electrode materials with 3D hierarchical microstructures and mechanical flexibility for lithium metal anodes.
基金financial support from National Natural Science Foundation of China(91534123,91834303,U1862117)supported by the State Key Laboratory of Multiphase Complex Systems(MPCS-2017-A-01)support by State key laboratory of Multiphase Complex Systems(MPCS)Facility Upgradation Program
文摘Here we report a strategy to enhance the energy density of supercapacitors by increasing the utilization rate of the specific surface area(SSA)via wettability improvement. The nonporous gold(NPG) film is used as the electrodes and the ionic liquid [EMIM]BF4 is the electrolyte. When the electrode is coated by paraffin, an increase of the contact angle leads to a remarkable reduction of the specific capacitance. While when acetonitrile is added into the electrolyte, the contact angle is decreased and the utilization rate of SSA is improved, which results in an increase of the specific capacitance. The addition of isopropyl acetate into the electrolyte leads to a further increase of the specific capacitance. To generalize the role of the wettability in improving the energy density, a carbon-based electrode is evaluated in the solution of potassium hydroxide. An addition of propyl alcohol into the potassium hydroxide solution leads to an increase of the specific capacitance, as well as a long-term stability of the supercapacitor. The role of conductivity in this study is excluded by designing experiments. This paper highlights the significance of wettability in determining the specific capacitance, showing an alternative to improve the energy density of supercapacitors.
基金supported by National Natural Science Foundation of China(Nos.91934302,21878078 and 21808056)。
文摘Whereas the proper choice of reaction solvent constitutes the cornerstone of the green solvent concept,solvent effects on chemical reactions are not mechanistically well understood due to the lack of feasible molecular models.Herein,by taking the case study of nucleophilic addition reaction in aqueous solution,we extend the proposed multiscale reaction density functional theory(RxDFT)method to investigate the intrinsic free energy profile and total free energy profile,and study the solvent effect on the activation and reaction free energy for the nucleophilic addition reactions of hydroxide anion with methanal and carbon dioxide in aqueous solution.The predictions of the free energy profile in aqueous solution for these two nucleophilic addition reactions from RxDFT have a satisfactory agreement with the results from the RISM and MD-FEP simulation.Meanwhile,the solvent effect is successfully addressed by examining the difference of the free energy profile between the gas phase and aqueous phase.In addition,we investigate the solvent effect on the reactions occurred near solid-liquid interfaces.It is shown that the activation free energy is significantly depressed when reaction takes place in the region within 10A distance to the substrate surface owing to the decrease of hydration free energy at the solid-liquid interface.
基金supported by National Natural Science Foundation of China(21878078,22108022)PetroChina Scientific Research and Technology Development Project(2018A-0907)。
文摘Whereas theπ-πstacking interactions at oil/water interfaces can affect interfacial structures hence the interfacial properties,the underlying microscopic mechanism remains largely unknown.We reported an all-atom molecular dynamics(MD)simulation study to demonstrate how the Gemini surfactants with pyrenyl groups affect the interracial properties,structural conformations,and the motion of molecules in the water/n-octane/surfactant ternary systems.It is found that the pyrenyl groups tend to be vertical to the interface owing to theπ-πstacking interaction.Besides,a synergistic effect between theπ-πinteraction and steric hindrance is found,which jointly affects the coalescence of liquid droplets.Therefore,the existence of aromatic groups and a moderate number of surfactants helps to form microemulsion.This work provides a molecular understanding of Gemini surfactants with aromatic groups in microemulsion preparation and applications.
基金supported by the National Science Foundation of China(21878144,21729601 and 21838004)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(21921006)+3 种基金Project of Jiangsu Natural Science Foundation of China(BK20171464)Project of Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)the Kempe Foundation in Swedena grant of Ministry of Research and Innovation,CNCS-UEFISCDI,project number PN-III-P4-ID-PCCF-2016-0050,within PNCDI III and the Swedish Science Council(VR)。
文摘The dehydration of water by dimethyl carbonate(DMC)is of great significance for its application in electrochemistry and oil industry.With the rapid development of nanomaterial,one-dimensional(e.g.carbon nanotube(CNT))and two-dimensional(e.g.lamellar graphene)materials have been widely used for molecular sieving.In this work,the molecular behavior of dimethyl carbonate/water mixture confined in CNT with varying diameters was studied based on molecular dynamics simulation.Due to different van der Waals interactions for the components in the mixtures with the solid surface,DMC molecules are preferentially adsorbed on the inner surface of the pore wall and formed an adsorption layer.Comparing with the pure water molecules confined in CNT,the adsorption DMC layer shows notable effect on the local compositions and microstructures of water molecules under nanoconfinement,which may result in different water mobility.Our analysis shows that the surface-induced DMC molecules can destroy the hydrogen bonding network of water molecules and result in an uniform and dispersed distribution of water molecules in the tube.These clear molecular understandings can be useful in material design for membrane separation.
基金National Natural Science Foundation of China(Nos.21978079,and 21878078).
文摘It is important to study the solvent effect on keto-enol tautomerism that has applications in many areas of chemical engineering.In this work,we use a multiscale reaction density functional theory(Rx DFT)to study the keto-enol tautomerism and isomerization of pyruvic acid.The results show that both effects of solvation and water assistance could reduce the reaction barriers.The water molecule participates the reaction as a catalyst to accept/give the protons with forming a hexagonal ring in the transition state.As a result of this temporary and intermediate hexagonal ring,the solute configuration undergoes a small variation during the reaction,giving a diminished contribution to the intrinsic reaction free energy.The solvent distribution shows a local ordering behavior near the solute that also reduces the contribution of solvation effect to the reaction barrier.Water assistance plays a major role in both pre-reaction and postreaction process.In terms of the driving force for the reaction,the effects of both solvation and water assistance are important.
基金supported by the National Natural Science Foundation of China (No.22278128)。
文摘Crystal habit and crystal form are critical elements in determining product properties and functions. In this work, we developed a microfluidic antisolvent crystallization technique to rapidly screen and accurately control the solid form and crystal habit of triphenylmethanol(Ph_(3)COH). This advanced technique separates the primary mixing of solutions from crystal formation(nucleation and growth) by introducing the microfluidic device, avoiding clogging in microchannels to obtain high-quality crystals. The results show that we can achieve controllable preparation of pure 2Ph_(3)COH·DMSO(DMSO solvate), pure Ph_(3)COH(form β), and mixed crystals with different mass ratios. Moreover, the microscale can prompt the DMSO solvate to grow into hexagonal sheet-like and bulk crystals. We can regulate the aspect ratio of hexagonal sheet-like crystals in binary solvents and control the crystal habit of the form β to transition between long needle-like shapes and short hexagonal prisms in DMF-H_(2)O. Meanwhile, we revealed that the solvent ratio, the antisolvent flow rate, and the initial concentration of Ph_(3)COH are the main factors affecting the solid form selectivity and morphology transition. Such a novel method would be considered as a promising technique to be extended to screen and control key crystallization parameters of other substances.
基金supported by the Natural Science Foundation of the Science and Technology Commission of Shanghai Municipality(No.19ZR1472200)National Natural Science Foundation of China(No.22178072)。
文摘In this work, a liquid-gas heterogeneous microreactor was developed for investigating continuous crystallization of dolutegravir sodium(DTG), as well as revealing reaction kinetics and mixing mechanism with 3-min data acquisition. The reaction kinetics models were established by visually recording the concentration variation of reactants over time in the microchannel via adding pH-sensitive fluorescent dye. The mixing intensification mechanism of liquid-gas flow was quantified through the fluorescent signal to indicate mixing process, demonstrating an outstanding mixing performance with a mixing time less than 0.1 s. Compared with batch crystallization, continuous synthesis of dolutegravir sodium using liquid-gas heterogenous microreactor optimizes crystal distribution size, and successfully modifies the crystal morphology in needle-like habit instead of rod-like habit. The microreactor continuous crystallization can run for 5 h without crystal blockage and achieve D90 of DTG less than 30 μm. This work provides a feasible approach for continuously synthesizing dolutegravir sodium, and can optimize the existing pharmaceutical crystallization.
基金the National Natural Science Foundation of China(Nos.91434110 and U1707602)the National Natural Science Foundation of China for Innovative Research Groups(No.51621002)+2 种基金the 111 Project of China(No.B08021)the PetroChina Innovation Foundation(No.2017D5007-0204)SZ acknowledges the support of the Fok Ying Tong Education Foundation(No.151069).
文摘A catalytic micro-reactor for converting hydrogen off-gas into water was recently developed, through which the conversion efficiency of hydrogen gas was greatly improved by hydrophobic modification of the catalytic substrate. Herein, a hybrid theoretical method is reported that combines density functional theory (DFT) on both the quantum and molecular scales. This method allows the microscopic study of the mechanism by which the surface catalytic reaction can be manipulated. Specifically, quantum DFT calculations are performed to quantify the molecular interaction between the catalytic substrate and reagent or product. Classical DFT investigations are subsequently carried out to determine the local concentrations of reagents near catalytic sites subject to different surface coating conditions. Finally, the reaction efficiency is determined from the local concentrations based on collision theory. This multiscale method provides molecular insight for quantifying the effect of catalytic surface modification on the reaction efficiency. The method reveals that an optimal surface hydrophobic modification can promote the densities of reagents near the substrate, while depleting the produced water. These two factors promote the conversion efficiency. The exclusion of produced water from the catalytic substrate is affected more by the degree of polymer grafting than by the chain length of hydrophobic polymer moieties.
基金supported by the National Natural Science Foundation of China(Nos.91934302,51762005,and 21878078)Key Projects of Guangxi Natural Science Foundation(No.2020GXNSFDA297015)+1 种基金the China Postdoctoral Science Foundation(No.2020M683617XB)the Opening Project of Guangxi Key Laboratory of Petrochemical Resource Processing and Process Intensification Technology(No.2020K006)。
文摘Electrochemical nitrogen reduction reaction(eNRR)is one of the most important chemical reactions for the production of ammonia under ambient environment.However,the lack of in-depth understanding of the structure-activity relationship impedes the development of high-performance catalysts for ammonia production.Herein,the density functional theory(DFT)calculations are performed to reveal the structure–activity relationship for the single-atom catalysts(SACs)supported on g-C_(3)N_(4),which is modified by molecular groups(i.e.,H,O,and OH).The computational results demonstrate that the W-based SACs are beneficial to produce ammonia with a low limiting potential(UL).Particularly,the W-OH@g-C_(3)N_(4) catalyst exhibits an ultralow UL of−0.22 V for eNRR.And the competitive eNRR selectivity can be identified by the dominant*N2 adsorption free energy than that of*H.Our findings provide a theoretical basis for the synthesis of efficient catalysts to produce ammonia.
基金supported by the National Natural Science Foundation of China (21772041, 201702062, 21811530005)the Program for Professor of Special Appointment (Eastern Scholar+2 种基金 GZ2016006)Shanghai Institutions of Higher Learning, Shanghai Pujiang Program (17PJ1401700)the Fundamental Research Funds for the Central Universities (WK1616004, 222201717003, 222201714013)
文摘Three new porphyrin dyes XW45-XW47 have been synthesized employing a dialkoxy-wrapped phenothiazine donor, a tetraalkoxy-wrapped porphyrin π-framework, a benzothiadiazole(BTD)-based auxiliary acceptor, and an anchoring benzoic acid group. On the basis of our previously reported dye XW36, XW45 was synthesized by introducing a BTD unit to broaden the absorption spectrum, further introducing a hexyl-substituent into the BTD unit afforded XW46, and an additional fluorine atom was introduced to the carboxyphenyl acceptor to afford XW47. As expected, the BTD unit obviously broadens and red-shifts the absorption threshold of XW45-XW47 to ca.750 nm. Dye-sensitized solar cells(DSSCs) were fabricated based on a cobalt electrolyte using chenodeoxycholic acid(CDCA) as the coadsorbent. Under full sun illumination, XW45 exhibits an efficiency of 9.73%, which is slightly lower than that of 10.19% obtained for the reference dye SM315. By contrast, XW46 and XW47 show higher efficiencies than SM315 owing to the improved anti-aggregation ability associated with the hexyl group on the BTD unit and better ICT effect induced by the fluorine atom on the carboxyphenyl unit. Thus, XW47 exhibits the highest efficiency of 10.41% among the porphyrin dyes. Furthermore, PT-C6 was used as the cosensitizer to improve the light harvesting ability and efficiencies of the cells due to its broad absorption within 350–560 nm. Thus, high efficiencies of 10.32%, 11.38% and 10.90% were achieved for the cosensitized solar cells based on XW45–XW47, respectively, owing to the obviously enhanced photocurrent density(JSC). In addition, under 30% full sun illumination, XW46+PT-C6 exhibits a high efficiency of 13.08%. These results give an effective method for building high performance DSSCs through the cosensitization of porphyrin dyes containing a wrapped donor, a wrapped porphyrin framework and a properly substituted auxiliary benzothiadiazole unit.
基金supported by the National Natural Science Foundation of China(21472047,91227201,91434110)the Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learning(GZ2016006)the Fundamental Research Funds for the Central Universities(WK1616004)
文摘Two fluorescence "turn-on" Zn^(2+) probes were developed by introducing an anthracenyl fluorophore through the linkage of a diphenylamino moiety at the 5-position of a dipyrrin moiety.Thus,two compounds with weak fluorescence were designed,synthesized,and employed as CHEF(chelation enhanced fluorescence) type fluorescence "turn-on" Zn^(2+) probes,which exhibit dramatic fluorescence enhancement upon addition of Zn^(2+),showing high sensitivities and impressive detection limits of 13 and12 nM,respectively,better than their analogues containing simple aryl substituents at the 5 positions of a di-or tripyrrin moiety.In addition,both of the probes exhibit good selectivity,short response time of less than 10 s and wide applicable pH ranges.Furthermore,the weak fluorescence nature of the probes was rationalized based on viscosity dependence measurements and theoretical calculations.These results provide further insight into the development of selective and sensitive zinc probes.