Novel dual-ionic imidazolium salts are shown to display excellent catalytic activity for cycloaddition of carbon dioxide and epoxides under room temperature and atmospheric pressure(0.1 MPa)without any solvent and co-...Novel dual-ionic imidazolium salts are shown to display excellent catalytic activity for cycloaddition of carbon dioxide and epoxides under room temperature and atmospheric pressure(0.1 MPa)without any solvent and co-catalyst leading to 96.1%product yield.It can be reused five times to keep the product yield over 90%.These intriguing results are attributed to a new reaction mechanism,which is supported by theoretical calculations along with the measurements of ^(13)C NMR spectrum and Fourier transform infrared spectroscopy(FT-IR).The excellent catalytic activity can be traced to a CO_(2)-philic group along with an electrophilic hydrogen atom.Our work shows that incorporation of CO_(2)-philic group is an feasible pathway to develop the new efficient ionic liquids.展开更多
Understanding the seven coordination and O-O coupling pathway of the distinguished Ru-bda catalysts is essential for the development of next generation efficient water-oxidation catalysts based on earthabundant metals...Understanding the seven coordination and O-O coupling pathway of the distinguished Ru-bda catalysts is essential for the development of next generation efficient water-oxidation catalysts based on earthabundant metals.This work reports the synthesis,characterization and catalytic properties of a monomeric ruthenium catalyst Ru-bnda(H2 bnda=2,2’-bi(nicotinic acid)-6,6’-dicarboxylic acid)featuring steric hindrance and enhanced hydrophilicity on the backbone.Combining experimental evidence with systematic density functional theory calculations on the Ru-bnda and related catalysts Ru-bda(H_(2)bda=2,2’-bipyridine-6,6’-dicarboxylic acid),Ru-pda(H_(2)pda=1,10-phenanthroline-2,9-dicarboxylic acid),and Ru-biqa(H_(2)biqa=(1,1’-biisoquinoline)-3,3’-dicarboxylic acid),we emphasized that seven coordination clearly determines presence of Ru^(Ⅴ)=O with high spin density on the ORu^(Ⅴ)=O atom,i.e.oxo with radical properties,which is one of the necessary conditions for reacting through the O-O coupling pathway.However,an additional factor to make the condition sufficient is the favorable intermolecular faceto-face interaction for the generation of the pre-reactive[Ru^(Ⅴ)=O…O=Ru^(Ⅴ)],which may be significantly influenced by the secondary coordination environments.This work provides a new understanding of the structure-activity relationship of water-oxidation catalysts and their potential to adopt I2M pathway for O-O bond formation.展开更多
基金supported by the National Natural Science Foundation of China(21975064)Program of Henan Center for Outstanding Overseas Scientists(GZS2020011)+1 种基金Henan University's first-class discipline science and technology research project(2018YLTD07,2018YLZDYJ11,2019YLZDYJ09)the Excellent Foreign Experts Project of Henan University。
文摘Novel dual-ionic imidazolium salts are shown to display excellent catalytic activity for cycloaddition of carbon dioxide and epoxides under room temperature and atmospheric pressure(0.1 MPa)without any solvent and co-catalyst leading to 96.1%product yield.It can be reused five times to keep the product yield over 90%.These intriguing results are attributed to a new reaction mechanism,which is supported by theoretical calculations along with the measurements of ^(13)C NMR spectrum and Fourier transform infrared spectroscopy(FT-IR).The excellent catalytic activity can be traced to a CO_(2)-philic group along with an electrophilic hydrogen atom.Our work shows that incorporation of CO_(2)-philic group is an feasible pathway to develop the new efficient ionic liquids.
基金the financial support from the Swedish Research Council(2017-00935)Swedish Energy Agency+3 种基金the Knut and Alice Wallenberg Foundationthe National Natural Science Foundation of China(21120102036)the National Basic Research Program of China(973 program,2014CB239402)the China Scholarship Council(CSC)。
文摘Understanding the seven coordination and O-O coupling pathway of the distinguished Ru-bda catalysts is essential for the development of next generation efficient water-oxidation catalysts based on earthabundant metals.This work reports the synthesis,characterization and catalytic properties of a monomeric ruthenium catalyst Ru-bnda(H2 bnda=2,2’-bi(nicotinic acid)-6,6’-dicarboxylic acid)featuring steric hindrance and enhanced hydrophilicity on the backbone.Combining experimental evidence with systematic density functional theory calculations on the Ru-bnda and related catalysts Ru-bda(H_(2)bda=2,2’-bipyridine-6,6’-dicarboxylic acid),Ru-pda(H_(2)pda=1,10-phenanthroline-2,9-dicarboxylic acid),and Ru-biqa(H_(2)biqa=(1,1’-biisoquinoline)-3,3’-dicarboxylic acid),we emphasized that seven coordination clearly determines presence of Ru^(Ⅴ)=O with high spin density on the ORu^(Ⅴ)=O atom,i.e.oxo with radical properties,which is one of the necessary conditions for reacting through the O-O coupling pathway.However,an additional factor to make the condition sufficient is the favorable intermolecular faceto-face interaction for the generation of the pre-reactive[Ru^(Ⅴ)=O…O=Ru^(Ⅴ)],which may be significantly influenced by the secondary coordination environments.This work provides a new understanding of the structure-activity relationship of water-oxidation catalysts and their potential to adopt I2M pathway for O-O bond formation.