The enantioselective reduction of keto oxime ether with borane catalyzed by oxazaborolidine is discussed by the density functional theory (DFT) method. The main intermediates and transition states for this reaction ar...The enantioselective reduction of keto oxime ether with borane catalyzed by oxazaborolidine is discussed by the density functional theory (DFT) method. The main intermediates and transition states for this reaction are optimized completely at the B3LYP/6-31g(d) level, and the transition states are verified by vibrational modes. As shown, the chirality-controlled steps for this re- action are the hydride transfer from borane to carbonyl carbon and oxime carbon of keto oxime ether, and the chirality for the reduced products is determined in these two reaction steps. In all examined reaction paths, the first hydride is transferred via a six-membered ring and the second hydride via a five-membered ring or a four-membered ring.展开更多
A simple and efficient C--N cross-coupling method of aryl halides with various heterocycles was reported, by using 10 tool% of CuI as catalyst and 1.2 equiv. Nail as base. Aryl iodides, aryl bromides and many substitu...A simple and efficient C--N cross-coupling method of aryl halides with various heterocycles was reported, by using 10 tool% of CuI as catalyst and 1.2 equiv. Nail as base. Aryl iodides, aryl bromides and many substituted atyl chlorides could efficiently react with heterocycles, providing variety of N-arylated products in good to excellent yields. The ligand-free catalyst system was stable in air and could be readily reused.展开更多
TiO2‐mediated photocatalysis is widely used in a variety of applications and products in the envi‐ronmental and energy fields, including photoelectrochemical conversion, self‐cleaning surfaces, and especially water...TiO2‐mediated photocatalysis is widely used in a variety of applications and products in the envi‐ronmental and energy fields, including photoelectrochemical conversion, self‐cleaning surfaces, and especially water purification systems. The dimensionality of the structure of a TiO2 material can affect its properties, functions, and more specifically, its photocatalytic performance. In this work, the photocatalytic inactivation of Gram‐negative Escherichia coli using three photocatalysts, differ‐ing in their structure and other characteristics, was studied in a batch reactor under UVA light. The aim was to establish the disinfection efficiency of solid TiO2 compared with that of suspended cata‐lysts, widely considered as reference cases for photocatalytic water disinfection. The bacterial inac‐tivation profiles obtained showed that: (1) the photoinactivation was exclusively related to the quantity of photons retained per unit of treated volume, irrespective of the characteristics of the photocatalyst and the emitted light flux densities;(2) across the whole UV light range studied, each of the photocatalytic solids was able to achieve more than 2 log bacterial inactivation with less than 2 h UV irradiation;(3) none of the used catalysts achieved a total bacterial disinfection during the treatment time. For each of the catalysts the quantum yield has been assessed in terms of disinfec‐tion efficiency, the 2D material showed almost the same performance as those of suspended cata‐lysts. This catalyst is promising for supported photocatalysis applications.展开更多
Hierarchically nanostructured, porous TiO_2(B) microspheres were synthesized by a microwave-assisted solvothermal method combined with subsequent heat treatment in air. The materials were carefully characterized by sc...Hierarchically nanostructured, porous TiO_2(B) microspheres were synthesized by a microwave-assisted solvothermal method combined with subsequent heat treatment in air. The materials were carefully characterized by scanning and transmission electron microscopy, X-ray diffraction, CO_2 adsorption, and a range of spectroscopies, including Raman, infrared, X-ray photoelectron and UV-Vis spectroscopy. The hierarchical TiO_2(B) particles are constructed by ultrathin nanosheets and possess large specific surface area, which provided many active sites for CO_2 adsorption as well as CO_2 conversion. The TiO_2(B)nanostructures exhibited marked photocatalytic activity for CO_2 reduction to methane and methanol. Anatase TiO_2 and P25 were used as the reference photocatalysts. Transient photocurrent measurement also proved the higher photoactivity of TiO_2(B) than that of anatase TiO_2. In-situ infrared spectrum was measured to identify the intermediates and deduce the conversion process of CO_2 under illumination over TiO_2(B) photocatalyst.展开更多
Direct alkylation of arenols with alky] organometallic reagents has never been approached, Herein we reported the first successful example of nickel-catalyzed methylation of arenols with methyl Grignard reagents to co...Direct alkylation of arenols with alky] organometallic reagents has never been approached, Herein we reported the first successful example of nickel-catalyzed methylation of arenols with methyl Grignard reagents to construct C（sp2）-C（sp3） bond under mild conditions. The transformation was compatible with broad substrate scope of 2-naphthol derivatives. Benzyl alcohol and biphenols were also suitable substrates for this methylation.展开更多
文摘The enantioselective reduction of keto oxime ether with borane catalyzed by oxazaborolidine is discussed by the density functional theory (DFT) method. The main intermediates and transition states for this reaction are optimized completely at the B3LYP/6-31g(d) level, and the transition states are verified by vibrational modes. As shown, the chirality-controlled steps for this re- action are the hydride transfer from borane to carbonyl carbon and oxime carbon of keto oxime ether, and the chirality for the reduced products is determined in these two reaction steps. In all examined reaction paths, the first hydride is transferred via a six-membered ring and the second hydride via a five-membered ring or a four-membered ring.
基金This work was supported by the National Natural Science Foundation of China （No. 20802049）.
文摘A simple and efficient C--N cross-coupling method of aryl halides with various heterocycles was reported, by using 10 tool% of CuI as catalyst and 1.2 equiv. Nail as base. Aryl iodides, aryl bromides and many substituted atyl chlorides could efficiently react with heterocycles, providing variety of N-arylated products in good to excellent yields. The ligand-free catalyst system was stable in air and could be readily reused.
基金supported by the "Community of Pyrenees Work" in 2012-2014 and the "future researcher" in 2013-2015
文摘TiO2‐mediated photocatalysis is widely used in a variety of applications and products in the envi‐ronmental and energy fields, including photoelectrochemical conversion, self‐cleaning surfaces, and especially water purification systems. The dimensionality of the structure of a TiO2 material can affect its properties, functions, and more specifically, its photocatalytic performance. In this work, the photocatalytic inactivation of Gram‐negative Escherichia coli using three photocatalysts, differ‐ing in their structure and other characteristics, was studied in a batch reactor under UVA light. The aim was to establish the disinfection efficiency of solid TiO2 compared with that of suspended cata‐lysts, widely considered as reference cases for photocatalytic water disinfection. The bacterial inac‐tivation profiles obtained showed that: (1) the photoinactivation was exclusively related to the quantity of photons retained per unit of treated volume, irrespective of the characteristics of the photocatalyst and the emitted light flux densities;(2) across the whole UV light range studied, each of the photocatalytic solids was able to achieve more than 2 log bacterial inactivation with less than 2 h UV irradiation;(3) none of the used catalysts achieved a total bacterial disinfection during the treatment time. For each of the catalysts the quantum yield has been assessed in terms of disinfec‐tion efficiency, the 2D material showed almost the same performance as those of suspended cata‐lysts. This catalyst is promising for supported photocatalysis applications.
基金supported by the National Basic Research Program of China(2013CB632402)the National Natural Science Foundation of China(51320105001,21433007,51372190,21573170)+3 种基金the Natural Science Foundation of Hubei Province(2015CFA001)the Fundamental Research Funds for the Central Universities(WUT:2015-III-034)Innovative Research Funds of SKLWUT(2017-ZD-4)the Discovery Early Career Researcher Award(DECRA)by Australian Research Council(DE160101488)
文摘Hierarchically nanostructured, porous TiO_2(B) microspheres were synthesized by a microwave-assisted solvothermal method combined with subsequent heat treatment in air. The materials were carefully characterized by scanning and transmission electron microscopy, X-ray diffraction, CO_2 adsorption, and a range of spectroscopies, including Raman, infrared, X-ray photoelectron and UV-Vis spectroscopy. The hierarchical TiO_2(B) particles are constructed by ultrathin nanosheets and possess large specific surface area, which provided many active sites for CO_2 adsorption as well as CO_2 conversion. The TiO_2(B)nanostructures exhibited marked photocatalytic activity for CO_2 reduction to methane and methanol. Anatase TiO_2 and P25 were used as the reference photocatalysts. Transient photocurrent measurement also proved the higher photoactivity of TiO_2(B) than that of anatase TiO_2. In-situ infrared spectrum was measured to identify the intermediates and deduce the conversion process of CO_2 under illumination over TiO_2(B) photocatalyst.
文摘Direct alkylation of arenols with alky] organometallic reagents has never been approached, Herein we reported the first successful example of nickel-catalyzed methylation of arenols with methyl Grignard reagents to construct C（sp2）-C（sp3） bond under mild conditions. The transformation was compatible with broad substrate scope of 2-naphthol derivatives. Benzyl alcohol and biphenols were also suitable substrates for this methylation.
