Using density functional theory with generalized gradient approximation and hybrid functional, we studied the properties of energy, charge population, and vibration of CH2 and CH3 adsorbed on Cun （n=1-6） clusters. T...Using density functional theory with generalized gradient approximation and hybrid functional, we studied the properties of energy, charge population, and vibration of CH2 and CH3 adsorbed on Cun （n=1-6） clusters. The results show that the DFT calculation with the hybrid functional matches the experimental results better in both cases. The calculation results indicate that the adsorption of CH2 is stronger than that of CH3. During adsorption, the charges transfer from Cu to CH2 or CH3. The obtained vibrational frequencies for different modes of CH2 and CH3 adsorbed on Cun agree well with the experimental results for the adsorption on Cu（111） surface.展开更多
In the past decade,transition-metal-catalyzed C–H functionalization by weak coordination has emerged as a practical and powerful tool to access many valuable chemicals.Two classes of weakly coordinating directing gro...In the past decade,transition-metal-catalyzed C–H functionalization by weak coordination has emerged as a practical and powerful tool to access many valuable chemicals.Two classes of weakly coordinating directing groups,commonly occurring functional groups,and easily removable auxiliaries,have been found to be efficient and practical for C–H activation reactions.This mini-review contains examples of recent research advances on transition-metal-catalyzed SP2 C–H functionalization via weak coordination,using Ru,Rh,and Pd.A number of weakly coordinating functional groups(e.g.,ketone,ester,carbamate,tertiary amide,ether,thioether,alcohol,and some others)are covered.As the field of transition-metal-catalyzed C–H functionalization continues to develop and more synthetically useful chemo-,regio-,and enantioselective reactions catalyzed by transition metal via weak coordination are discovered,this promising and attractive strategy will play a more important role in modern organic synthesis.展开更多
To improve the contact between platinum catalyst and titanium substrate, a layer of TiO2 nanotube arrays has been synthesized before depositing Pt nanoflowers by pulse electrodeposition. Dramatic improvements in elect...To improve the contact between platinum catalyst and titanium substrate, a layer of TiO2 nanotube arrays has been synthesized before depositing Pt nanoflowers by pulse electrodeposition. Dramatic improvements in electrocatalytic activity （3x） and stability （60x） for methanol oxidation were found, suggesting promising applications in direct methanol fuel cells. The 3x and 60x improvements persist for Pt/Pd catalysts used to overcome the CO poisoning problem.展开更多
The iron containing ionic liquid 1-butyl-3-methylimidazolium tetrachloroferrate （[C4mim]C1/FeCl3; Z = 0.5） proved to be an efficient catalyst for the solvent-free metal catalyzed Michael addition of β-keto esters a...The iron containing ionic liquid 1-butyl-3-methylimidazolium tetrachloroferrate （[C4mim]C1/FeCl3; Z = 0.5） proved to be an efficient catalyst for the solvent-free metal catalyzed Michael addition of β-keto esters and enones. Due to the ionic structure of the catalyst, a significant acceleration of the reaction rate was observed under microwave conditions. Furthermore, recycling of the ionic liquid catalyst could be performed after simply distilling off the products.展开更多
Two types of lanthanide coordination polymers, namely, [Ln（PA）（NO3）（DMA）3]n （Ln=Gd （1）, Dy （2）, Eu （3）, Tb （4）） （type I）, and {[Ln2（PA）3（DMF）4]＇2DMF} （Ln=Eu （5）, Tb （6）） （type II） （PA=P...Two types of lanthanide coordination polymers, namely, [Ln（PA）（NO3）（DMA）3]n （Ln=Gd （1）, Dy （2）, Eu （3）, Tb （4）） （type I）, and {[Ln2（PA）3（DMF）4]＇2DMF} （Ln=Eu （5）, Tb （6）） （type II） （PA=Pamoic acid, DMA=dimethylacetamide, DMF=N,N-dimethylformamide）, have been synthesized by the reaction of Ln（NO3）a-6H20 with pamoic acid through layer diffusion method. These complexes were characterized by single crystal X-ray diffraction, infrared spectroscopy （IR）, thermogravimetric analysis （TGA）, fluorescence and magnetic measurements. Solvents and lanthanide atoms in the reaction play an important role in controlling different structures. Type I demonstrated 1-D linear chain structure connected by Ln atoms and PA ligands. Type II exhibited non-interpenetrating 3-D 6-connected 43612 nets based on binuclear [Ln2（CO2）6（DMF）4] cores. Magnetic properties of complexes 1-4 were investigated in details. Complex 1 shows significant magnetocaloric effect with -△Sm=20.37 J kg^-1 K^-1 at 3.0 K and 7 T. Complex 2 exhibits slow relaxation of the magnetization. Complexes 3-6 exhibit both ligand- and metal-centered fluorescent properties. Complex 6 demonstrates fluorescent sensing of DMF and Cu^2＋ ion.展开更多
基金This work was supported by the Chinese Academy of Engineering Physics （No.51480030105JW1301） and the National Natural Science Foundation of China （No.10534010, No.10374036, and No.10374037）.
文摘Using density functional theory with generalized gradient approximation and hybrid functional, we studied the properties of energy, charge population, and vibration of CH2 and CH3 adsorbed on Cun （n=1-6） clusters. The results show that the DFT calculation with the hybrid functional matches the experimental results better in both cases. The calculation results indicate that the adsorption of CH2 is stronger than that of CH3. During adsorption, the charges transfer from Cu to CH2 or CH3. The obtained vibrational frequencies for different modes of CH2 and CH3 adsorbed on Cun agree well with the experimental results for the adsorption on Cu（111） surface.
基金supported by the National Basic Research Program of China(2011CB965300)the National Natural Science Foundation of China(21142008,21302106)Tsinghua University 985 Phase II Funds,and the Tsinghua University Initiative Scientific Research Program
文摘In the past decade,transition-metal-catalyzed C–H functionalization by weak coordination has emerged as a practical and powerful tool to access many valuable chemicals.Two classes of weakly coordinating directing groups,commonly occurring functional groups,and easily removable auxiliaries,have been found to be efficient and practical for C–H activation reactions.This mini-review contains examples of recent research advances on transition-metal-catalyzed SP2 C–H functionalization via weak coordination,using Ru,Rh,and Pd.A number of weakly coordinating functional groups(e.g.,ketone,ester,carbamate,tertiary amide,ether,thioether,alcohol,and some others)are covered.As the field of transition-metal-catalyzed C–H functionalization continues to develop and more synthetically useful chemo-,regio-,and enantioselective reactions catalyzed by transition metal via weak coordination are discovered,this promising and attractive strategy will play a more important role in modern organic synthesis.
文摘To improve the contact between platinum catalyst and titanium substrate, a layer of TiO2 nanotube arrays has been synthesized before depositing Pt nanoflowers by pulse electrodeposition. Dramatic improvements in electrocatalytic activity （3x） and stability （60x） for methanol oxidation were found, suggesting promising applications in direct methanol fuel cells. The 3x and 60x improvements persist for Pt/Pd catalysts used to overcome the CO poisoning problem.
基金financially supported by the Hochschuljubil umsstiftung der Stadt Wien
文摘The iron containing ionic liquid 1-butyl-3-methylimidazolium tetrachloroferrate （[C4mim]C1/FeCl3; Z = 0.5） proved to be an efficient catalyst for the solvent-free metal catalyzed Michael addition of β-keto esters and enones. Due to the ionic structure of the catalyst, a significant acceleration of the reaction rate was observed under microwave conditions. Furthermore, recycling of the ionic liquid catalyst could be performed after simply distilling off the products.
基金supported by the National Natural Science Foundation of China(21571092,21403102)the Natural Science Foundation of Shandong Province(ZR2012BQ023)the University Scientific Research Development Plan of the Education Department of Shandong Province(J14LC10)
文摘Two types of lanthanide coordination polymers, namely, [Ln（PA）（NO3）（DMA）3]n （Ln=Gd （1）, Dy （2）, Eu （3）, Tb （4）） （type I）, and {[Ln2（PA）3（DMF）4]＇2DMF} （Ln=Eu （5）, Tb （6）） （type II） （PA=Pamoic acid, DMA=dimethylacetamide, DMF=N,N-dimethylformamide）, have been synthesized by the reaction of Ln（NO3）a-6H20 with pamoic acid through layer diffusion method. These complexes were characterized by single crystal X-ray diffraction, infrared spectroscopy （IR）, thermogravimetric analysis （TGA）, fluorescence and magnetic measurements. Solvents and lanthanide atoms in the reaction play an important role in controlling different structures. Type I demonstrated 1-D linear chain structure connected by Ln atoms and PA ligands. Type II exhibited non-interpenetrating 3-D 6-connected 43612 nets based on binuclear [Ln2（CO2）6（DMF）4] cores. Magnetic properties of complexes 1-4 were investigated in details. Complex 1 shows significant magnetocaloric effect with -△Sm=20.37 J kg^-1 K^-1 at 3.0 K and 7 T. Complex 2 exhibits slow relaxation of the magnetization. Complexes 3-6 exhibit both ligand- and metal-centered fluorescent properties. Complex 6 demonstrates fluorescent sensing of DMF and Cu^2＋ ion.
