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
A family of responsive enaminitrile molecular switches showing tunable turn-on fluorescence upon switching and aggregation is reported.When activated by the addition of acid/base,isomerization around the C═C bond cou...A family of responsive enaminitrile molecular switches showing tunable turn-on fluorescence upon switching and aggregation is reported.When activated by the addition of acid/base,isomerization around the C═C bond could be effectuated,resulting in complete and reversible switching to the E-or Z-isomers.Typical aggregation-induced emission(AIE)could be recorded for one specific state of the different switches.By subtle tailoring of the parent structure,a series of compounds with emissions covering almost the full visible color range were obtained.The switchable AIE features of the enaminitrile structures enabled their demonstration as solid-state chemosensors to detect acidic and basic vapors,where the emission displayed an“off-on-off”effect.Furthermore,switching to the Z-configuration could be driven out-of-equilibrium through transient changes in acidity while giving rise to fluorescence.Single-crystal X-ray diffraction measurements suggested a luminescence mechanism based on restriction of intramolecular rotation and an intramolecular charge transfer effect in the AIE luminogens.展开更多
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.
文摘A family of responsive enaminitrile molecular switches showing tunable turn-on fluorescence upon switching and aggregation is reported.When activated by the addition of acid/base,isomerization around the C═C bond could be effectuated,resulting in complete and reversible switching to the E-or Z-isomers.Typical aggregation-induced emission(AIE)could be recorded for one specific state of the different switches.By subtle tailoring of the parent structure,a series of compounds with emissions covering almost the full visible color range were obtained.The switchable AIE features of the enaminitrile structures enabled their demonstration as solid-state chemosensors to detect acidic and basic vapors,where the emission displayed an“off-on-off”effect.Furthermore,switching to the Z-configuration could be driven out-of-equilibrium through transient changes in acidity while giving rise to fluorescence.Single-crystal X-ray diffraction measurements suggested a luminescence mechanism based on restriction of intramolecular rotation and an intramolecular charge transfer effect in the AIE luminogens.
