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
Numerous aspects of the water oxidation mechanism in photosystemⅡhave not been fully elucidated,especially the O-O bond formation pathway.However,a body of experimental evidences have identified the O5 and W2 ligands...Numerous aspects of the water oxidation mechanism in photosystemⅡhave not been fully elucidated,especially the O-O bond formation pathway.However,a body of experimental evidences have identified the O5 and W2 ligands of the oxygen-evolving complex as the highly probable substrate candidates.In this work,we studied O-O bond formation between O5 and W2 based on the native Mn4 Ca cluster by density functional calculations.Structural rearrangements before the formation of the S_(4) state were found as a prerequisite for O-O bond formation between O5 and W2,regardless if the suggested pathways involving the typical Mnl(Ⅳ)-O·species or the recently proposed Mn4(Ⅶ)(O)2 species.Possible alternatives for the S2→S_(3) and S_(3)→S_(4) transitions accounting for such required rearrangements are discussed.These findings reflect that the structural flexibility of the Mn4 Ca cluster is essential to allow structural rearrangements during the catalytic cycle.展开更多
Electrocatalytic ammonia oxidation reaction(eAOR)is of significance to ammonia fuel economy and the production of valuable N-containing products,such as nitrite,nitrate and hydrazine.The study of well-defined molecula...Electrocatalytic ammonia oxidation reaction(eAOR)is of significance to ammonia fuel economy and the production of valuable N-containing products,such as nitrite,nitrate and hydrazine.The study of well-defined molecular catalysts offers rich insights in terms of the detailed mechanism of ammonia oxidation.This review analyzes the thermodynamics of ammonia oxidation reactions and summarizes the current progress in molecular electrocatalysts in this booming field.We emphasized the factors that influence the selectivity of products and further discussed the challenges in designing efficient catalysts.展开更多
Fuels and oleochemicals have been chemically produced fromabundant biological oils or fatty acids for more than a century,and modern biotechnology is now accelerating the advances infatty acid chemistry [1,2]. A numbe...Fuels and oleochemicals have been chemically produced fromabundant biological oils or fatty acids for more than a century,and modern biotechnology is now accelerating the advances infatty acid chemistry [1,2]. A number of enzymes responsible forthe biosynthesis of hydrocarbons from fatty acids have been discovered, providing a promising strategy for enzymatic synthesisof fatty hydrocarbons [3]. CYP152 peroxygenases have attracted agreat deal of attention due to their ability to one-step oxidativelydecarboxylate or hydroxylate fatty acids using H2O2 as sole oxidant, generating valuable a-olefins or hydroxylated fatty acids[4,5] (Fig. 1a). In addition to a-olefins as biofuels and chemicalintermediates, hydroxylated fatty acids are also an important classof compounds with various applications in food, cosmetic, pharmaceutical, and biomaterial industries [6,7] (Fig. 1b). Among them,P450BSb is considered as the most promising CYP152 peroxygenasefor practical applications due to its high stability and activity tocatalyze both b-hydroxylation (the preferred reaction) and decarboxylation (the side reaction) of fatty acids that are both mechanistically initiated by Cb-H abstraction. Of note, directed evolutioncould remodel its catalytic preference on decarboxylation orb-hydroxylation (e.g., the P450BSb-DC mutant with 67% decarboxylation selectivity) [5].展开更多
Isolation of RuⅢ-bda(17-electron specie)complex with an aqua ligand(2-electron donor)is challenging due to violation of the 18-electron rule.Although considerable efforts have been dedicated to mechanistic studies of...Isolation of RuⅢ-bda(17-electron specie)complex with an aqua ligand(2-electron donor)is challenging due to violation of the 18-electron rule.Although considerable efforts have been dedicated to mechanistic studies of water oxidation by the Ru-bda family,the structure and initial formation of the Ru^(Ⅲ)-bda aqua complex are still controversial.Herein,we challenge this often overlooked step by designing a pocketshape Ru-based complex 1.The computational studies showed that 1 possesses the crucial hydrophobicity at the Ru^(V)(O)state as well as similar probability of access of terminal O to solvent water molecules when compared with classic Ru-bda catalysts.Through characterization of single-crystal structures at the Ru^(Ⅱ) and Ru^(Ⅲ) states,a pseudo seven-coordinate“ready-togo”aqua ligand with Ru^(Ⅲ)…O distance of 3.62A was observed.This aqua ligand was also found to be part of a formed hydrogen-bonding network,providing a good indication of how the Ru^(Ⅲ)-OH_(2)complex is formed.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.
基金financial support of this work by the Swedish Research Council(2017-00935)Swedish Energy Agency and Knut and Alice Wallenberg Foundation(KAW 2016.0072)。
文摘Numerous aspects of the water oxidation mechanism in photosystemⅡhave not been fully elucidated,especially the O-O bond formation pathway.However,a body of experimental evidences have identified the O5 and W2 ligands of the oxygen-evolving complex as the highly probable substrate candidates.In this work,we studied O-O bond formation between O5 and W2 based on the native Mn4 Ca cluster by density functional calculations.Structural rearrangements before the formation of the S_(4) state were found as a prerequisite for O-O bond formation between O5 and W2,regardless if the suggested pathways involving the typical Mnl(Ⅳ)-O·species or the recently proposed Mn4(Ⅶ)(O)2 species.Possible alternatives for the S2→S_(3) and S_(3)→S_(4) transitions accounting for such required rearrangements are discussed.These findings reflect that the structural flexibility of the Mn4 Ca cluster is essential to allow structural rearrangements during the catalytic cycle.
基金supported by the National Key R&D Program of China(2022YFC3401802)the National Natural Science Foundation of China(22279105)+4 种基金the Zhejiang Provincial Natural Science Foundation(XHD24B0201)the Starting-up Package from Westlake Universitythe Kunpeng Research Fund from Zhejiang ProvinceResearch Center for Industries of the FutureZhejiang Baima Lake Laboratory。
文摘Electrocatalytic ammonia oxidation reaction(eAOR)is of significance to ammonia fuel economy and the production of valuable N-containing products,such as nitrite,nitrate and hydrazine.The study of well-defined molecular catalysts offers rich insights in terms of the detailed mechanism of ammonia oxidation.This review analyzes the thermodynamics of ammonia oxidation reactions and summarizes the current progress in molecular electrocatalysts in this booming field.We emphasized the factors that influence the selectivity of products and further discussed the challenges in designing efficient catalysts.
基金supported by the National Key Research and Development Program of China(2022YFC3401802)the National Natural Science Foundation of China(32025001,32300021,22279105,and 32200017)+3 种基金the China Postdoctoral Science Foundation(2022M710080 and 2021M701989)the Postdoctoral Innovation Project of Shandong Province(SDCX-ZG-202201005)the China National Postdoctoral Program for Innovative Talents(BX20220191),the Shandong Provincial Natural Science Foundation(ZR2019ZD20,ZR2023QC021,and ZR2022QC070)Qingdao Natural Science Foundation(23-2-1-25-zyyd-jch)。
文摘Fuels and oleochemicals have been chemically produced fromabundant biological oils or fatty acids for more than a century,and modern biotechnology is now accelerating the advances infatty acid chemistry [1,2]. A number of enzymes responsible forthe biosynthesis of hydrocarbons from fatty acids have been discovered, providing a promising strategy for enzymatic synthesisof fatty hydrocarbons [3]. CYP152 peroxygenases have attracted agreat deal of attention due to their ability to one-step oxidativelydecarboxylate or hydroxylate fatty acids using H2O2 as sole oxidant, generating valuable a-olefins or hydroxylated fatty acids[4,5] (Fig. 1a). In addition to a-olefins as biofuels and chemicalintermediates, hydroxylated fatty acids are also an important classof compounds with various applications in food, cosmetic, pharmaceutical, and biomaterial industries [6,7] (Fig. 1b). Among them,P450BSb is considered as the most promising CYP152 peroxygenasefor practical applications due to its high stability and activity tocatalyze both b-hydroxylation (the preferred reaction) and decarboxylation (the side reaction) of fatty acids that are both mechanistically initiated by Cb-H abstraction. Of note, directed evolutioncould remodel its catalytic preference on decarboxylation orb-hydroxylation (e.g., the P450BSb-DC mutant with 67% decarboxylation selectivity) [5].
基金financially supported by the Swedish Research Council(2017-00935)the Knut and Alice Wallenberg Foundation(KAW 2016.0072)the China Scholarship Council(CSC).
文摘Isolation of RuⅢ-bda(17-electron specie)complex with an aqua ligand(2-electron donor)is challenging due to violation of the 18-electron rule.Although considerable efforts have been dedicated to mechanistic studies of water oxidation by the Ru-bda family,the structure and initial formation of the Ru^(Ⅲ)-bda aqua complex are still controversial.Herein,we challenge this often overlooked step by designing a pocketshape Ru-based complex 1.The computational studies showed that 1 possesses the crucial hydrophobicity at the Ru^(V)(O)state as well as similar probability of access of terminal O to solvent water molecules when compared with classic Ru-bda catalysts.Through characterization of single-crystal structures at the Ru^(Ⅱ) and Ru^(Ⅲ) states,a pseudo seven-coordinate“ready-togo”aqua ligand with Ru^(Ⅲ)…O distance of 3.62A was observed.This aqua ligand was also found to be part of a formed hydrogen-bonding network,providing a good indication of how the Ru^(Ⅲ)-OH_(2)complex is formed.
