Pengfei Chen, Yafei Li, Jing Ma, Jun Zhu, Jin Xie, Miquel Solà, Congqing Zhu, Qin Zhu
Aromaticity is a cornerstone concept in chemistry, playing a crucial role in understanding molecular stability and reactivity. Traditionally, aromaticity has been primarily associated with cyclic planar conjugated organic molecules composed solely of carbon, but it has recently expanded to include metal-containing systems. However, metal-only aromatics remain extremely scarce. Here, we present the first neutral all-metal aromatic cluster with a rhombic geometry. X-ray crystallography reveals that the rhombic Al2Pd2 core is stabilized by an innovative double-layer N–P ligand framework, featuring essentially the same Al–Pd bond lengths (2.4706(4) and 2.4636(4) Å) and two planar tetracoordinate Al centers. Quantum chemical calculations provide compelling evidence for the two-electron σ-aromaticity in this molecule. Further research on the reactivity of the σ-aromatic Al2Pd2 cluster reveals that it can accept lone-pair electron coordination and act as a two-electron reducing agent. This study not only extends the concept of aromaticity to neutral all-metal rhombic systems but also opens new horizons for the synthesis and exploration of novel all-metal aromatic clusters.
{"title":"Neutral All-Metal σ-Aromaticity in a Rhombic Cluster","authors":"Pengfei Chen, Yafei Li, Jing Ma, Jun Zhu, Jin Xie, Miquel Solà, Congqing Zhu, Qin Zhu","doi":"10.1021/jacs.5c03828","DOIUrl":"https://doi.org/10.1021/jacs.5c03828","url":null,"abstract":"Aromaticity is a cornerstone concept in chemistry, playing a crucial role in understanding molecular stability and reactivity. Traditionally, aromaticity has been primarily associated with cyclic planar conjugated organic molecules composed solely of carbon, but it has recently expanded to include metal-containing systems. However, metal-only aromatics remain extremely scarce. Here, we present the first neutral all-metal aromatic cluster with a rhombic geometry. X-ray crystallography reveals that the rhombic Al<sub>2</sub>Pd<sub>2</sub> core is stabilized by an innovative double-layer N–P ligand framework, featuring essentially the same Al–Pd bond lengths (2.4706(4) and 2.4636(4) Å) and two planar tetracoordinate Al centers. Quantum chemical calculations provide compelling evidence for the two-electron σ-aromaticity in this molecule. Further research on the reactivity of the σ-aromatic Al<sub>2</sub>Pd<sub>2</sub> cluster reveals that it can accept lone-pair electron coordination and act as a two-electron reducing agent. This study not only extends the concept of aromaticity to neutral all-metal rhombic systems but also opens new horizons for the synthesis and exploration of novel all-metal aromatic clusters.","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":"65 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2025-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143849951","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Arvind Singh Heer, Harlan Mantelli, Qi Han, Nicholas Georgescu, Daniel Scherson
Changes in the electrostatic potential within an aqueous acidic solution induced by the passage of current between the Au disk of a stationary Au|Au ring disk electrode or stimulating electrode, SE, and a distant counter electrode made it possible to stimulate the reduction of selenous acid, H2SeO3, to elemental selenium at the concentric Au ring polarized at a fixed potential, just positive to its otherwise expected onset. This effect was ascribed to variations in the surface overpotential, ηs, and, thus, in the rates of H2SeO3 reduction along the ring, which we define, hereafter, as a monopolar electrode, ME. The stimulation efficiency could be accurately determined from a coulometric analysis of the peak for Se oxidation observed by subsequently scanning the ring linearly toward positive potentials to yield H2SeO3. Excellent quantitative agreement was obtained between the current flowing through the ME, IME, and EMEo, as a function of ISE, and theoretical simulations employing COMSOL using parameters extracted from independent measurements performed under otherwise identical experimental conditions. This novel tactic is expected to open new prospects for gaining insight into surface diffusion and other interfacial dynamics phenomena, as well as local modifications in the microstructure of electrodes, such as etching.
{"title":"Electrostatic Stimulation of Monopolar Electrodes","authors":"Arvind Singh Heer, Harlan Mantelli, Qi Han, Nicholas Georgescu, Daniel Scherson","doi":"10.1021/jacs.5c03256","DOIUrl":"https://doi.org/10.1021/jacs.5c03256","url":null,"abstract":"Changes in the electrostatic potential within an aqueous acidic solution induced by the passage of current between the Au disk of a stationary Au|Au ring disk electrode or stimulating electrode, SE, and a distant counter electrode made it possible to <i>stimulate</i> the reduction of selenous acid, H<sub>2</sub>SeO<sub>3</sub>, to elemental selenium at the concentric Au ring polarized at a fixed potential, just positive to its otherwise expected onset. This effect was ascribed to variations in the surface overpotential, η<sub>s</sub>, and, thus, in the rates of H<sub>2</sub>SeO<sub>3</sub> reduction along the ring, which we define, hereafter, as a <i>monopolar electrode,</i> ME. The <i>stimulation</i> efficiency could be accurately determined from a coulometric analysis of the peak for Se oxidation observed by subsequently scanning the ring linearly toward positive potentials to yield H<sub>2</sub>SeO<sub>3</sub>. Excellent quantitative agreement was obtained between the current flowing through the ME, <i>I</i><sub>ME</sub>, and <i>E</i><sub>ME</sub><sup>o</sup>, as a function of <i>I</i><sub>SE</sub>, and theoretical simulations employing COMSOL using parameters extracted from independent measurements performed under otherwise identical experimental conditions. This novel tactic is expected to open new prospects for gaining insight into surface diffusion and other interfacial dynamics phenomena, as well as local modifications in the microstructure of electrodes, such as etching.","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":"17 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143846543","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The building blocks of current life on Earth are chiral compounds, such as 2’-deoxy-D-ribose of DNA and L-amino acids with homochirality, which play an important role in various biological reactions. We investigated the effect of chirality on the template-directed chemical synthesis of nucleic acids as a model for primitive replication of genetic materials in the absence of enzymes. The efficiency of the template-directed chemical ligation of two acyclic nucleic acids, achiral serinol nucleic acid (SNA) and chiral acyclicl-threoninol nucleic acid (L-aTNA), induced by N-cyanoimidazole and a divalent metal cation, was evaluated. The chemical ligation of SNA fragments on an SNA template was much slower than the ligation of L-aTNA fragments on an L-aTNA template. Examination of L-aTNA and SNA heteroligation and the effects of chimeric template strands revealed the crucial importance of L-aTNA chirality, which induces helical propagation and fixes the local conformation of the reactive phosphate group for effective chemical ligation. DNA and RNA templates also enhanced the ligation of SNA and L-aTNA fragments. “Reverse transcription” from template RNA to L-aTNA was also demonstrated. Our findings show that scaffold chirality is crucial for chemical replication and reverse transcription in XNA-based systems. Furthermore, the reverse transcription from RNA to L-aTNA will find applications in XNA-based in vitro selection, the creation of artificial life, and nanotechnologies.
{"title":"Chirality-Promoted Chemical Ligation and Reverse Transcription of Acyclic Threoninol Nucleic Acid","authors":"Hikari Okita, Keiji Murayama, Hiroyuki Asanuma","doi":"10.1021/jacs.5c03128","DOIUrl":"https://doi.org/10.1021/jacs.5c03128","url":null,"abstract":"The building blocks of current life on Earth are chiral compounds, such as 2’-deoxy-<span>D</span>-ribose of DNA and <span>L</span>-amino acids with homochirality, which play an important role in various biological reactions. We investigated the effect of chirality on the template-directed chemical synthesis of nucleic acids as a model for primitive replication of genetic materials in the absence of enzymes. The efficiency of the template-directed chemical ligation of two <i>acyclic</i> nucleic acids, achiral serinol nucleic acid (SNA) and chiral <i>acyclic</i> <span>l</span>-threoninol nucleic acid (<span>L</span>-<i>a</i>TNA), induced by <i>N</i>-cyanoimidazole and a divalent metal cation, was evaluated. The chemical ligation of SNA fragments on an SNA template was much slower than the ligation of <span>L</span>-<i>a</i>TNA fragments on an <span>L</span>-<i>a</i>TNA template. Examination of <span>L</span>-<i>a</i>TNA and SNA heteroligation and the effects of chimeric template strands revealed the crucial importance of <span>L</span>-<i>a</i>TNA chirality, which induces helical propagation and fixes the local conformation of the reactive phosphate group for effective chemical ligation. DNA and RNA templates also enhanced the ligation of SNA and <span>L</span>-<i>a</i>TNA fragments. “Reverse transcription” from template RNA to <span>L</span>-<i>a</i>TNA was also demonstrated. Our findings show that scaffold chirality is crucial for chemical replication and reverse transcription in XNA-based systems. Furthermore, the reverse transcription from RNA to <span>L</span>-<i>a</i>TNA will find applications in XNA-based in vitro selection, the creation of artificial life, and nanotechnologies.","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":"30 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143846476","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Developing a low-cost and environmentally friendly method for lithium extraction is essential for the efficient recycling of spent lithium-ion battery (LIB) cathodes. Current technologies, such as solvent extraction/precipitation and electrochemical processes, rely on anion- or cation-rich extraction agents and necessitate further purification, leading to high energy consumption and waste pollution. Here, we demonstrate that applying mechanical treatment on ternary LIB cathodes enables water to extract lithium from the cathode materials under mild conditions, achieving Li extraction efficiencies of 99.4% for LiNi0.8Mn0.1Co0.1O2 (NMC811), 98.9% for LiNi0.9Co0.075Al0.025O2 (NCA), and 97.1% for LiNi0.9Mn0.05Co0.05O2 (NMC955) at 150 °C. This process involves an irreversible oxygen redox reaction, resulting in the structural transformation to metal hydroxide species. Further experiments revealed that mechanical treatment leads to the formation of oxygen holes (O2−δ), which are subsequently oxidized into O2 gas through O–O dimerization during the hydrothermal process, creating oxygen vacancies. These vacant sites then act as channels for the release of surrounding Li+ ions, followed by the OH– refilling process. Unlike previous methods, this work avoids the use of additional leaching reagents and produces high-quality end products, such as transition metal hydroxides and analytical-grade Li2CO3. Moreover, our proposed lithium extraction strategy further enables the recovered materials to be seamlessly reintegrated into the production of fresh cathode materials, providing valuable insights into the sustainable recycling of LIB cathodes.
{"title":"Irreversible Oxygen Redox Enables Lithium Extraction from Ternary Lithium-Ion Battery Cathodes in Water","authors":"Chao Wu, Qi Zhang, Haoyan Meng, Bo Wu, Yiming Zhang, Junhua Li, Ying Tang, Anqi Zou, Jiliang Zhu, Caozheng Diao, Feng Gao, Zhi Gen Yu, Junmin Xue, Shibo Xi, Xiaopeng Wang, Jiagang Wu","doi":"10.1021/jacs.5c00452","DOIUrl":"https://doi.org/10.1021/jacs.5c00452","url":null,"abstract":"Developing a low-cost and environmentally friendly method for lithium extraction is essential for the efficient recycling of spent lithium-ion battery (LIB) cathodes. Current technologies, such as solvent extraction/precipitation and electrochemical processes, rely on anion- or cation-rich extraction agents and necessitate further purification, leading to high energy consumption and waste pollution. Here, we demonstrate that applying mechanical treatment on ternary LIB cathodes enables water to extract lithium from the cathode materials under mild conditions, achieving Li extraction efficiencies of 99.4% for LiNi<sub>0.8</sub>Mn<sub>0.1</sub>Co<sub>0.1</sub>O<sub>2</sub> (NMC811), 98.9% for LiNi<sub>0.9</sub>Co<sub>0.075</sub>Al<sub>0.025</sub>O<sub>2</sub> (NCA), and 97.1% for LiNi<sub>0.9</sub>Mn<sub>0.05</sub>Co<sub>0.05</sub>O<sub>2</sub> (NMC955) at 150 °C. This process involves an irreversible oxygen redox reaction, resulting in the structural transformation to metal hydroxide species. Further experiments revealed that mechanical treatment leads to the formation of oxygen holes (O<sup>2−δ</sup>), which are subsequently oxidized into O<sub>2</sub> gas through O–O dimerization during the hydrothermal process, creating oxygen vacancies. These vacant sites then act as channels for the release of surrounding Li<sup>+</sup> ions, followed by the OH<sup>–</sup> refilling process. Unlike previous methods, this work avoids the use of additional leaching reagents and produces high-quality end products, such as transition metal hydroxides and analytical-grade Li<sub>2</sub>CO<sub>3</sub>. Moreover, our proposed lithium extraction strategy further enables the recovered materials to be seamlessly reintegrated into the production of fresh cathode materials, providing valuable insights into the sustainable recycling of LIB cathodes.","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":"7 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143846778","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The electrocatalytic reduction of nitric oxide (NO) to ammonia (NH3) represents an attractive alternative for valorizing waste NO streams (NORR). However, discovering efficient catalysts for NO-to-NH3 conversion remains challenging. We have designed metal-intercalated twisted graphene-BN heterostructures, in which metal atoms act as electron-transfer bridges. The twisted configuration facilitates cross-interface charge transfer, redistributing electrons from the graphene–metal interface to the metal–BN interface and BN surface. This electronic modulation enables boron atom adjacent to the metal center in BN to serve as active sites, promoting strong chemisorption and enhanced activation of NO. After high-throughput screening of the stability and NO capture ability of various transition metal-intercalated twisted heterostructures, we have investigated systematically the NORR pathways across 30 candidates. The results show that the rBN-Ti-Gθ and rBN-V-Gθ heterostructures exhibit exceptional NO-to-NH3 catalytic performance under optimized twisting conditions. Additionally, using sure independence screening and sparsifying operator (SISSO) for model training, we propose a descriptor and establish a relationship between the twist angle and catalytic activity. This study bridges the gap in applying twisted heterostructures to NORR electrocatalysis and provides new insights and strategies for designing high-performance NORR catalysts.
{"title":"Design of Twisted Two-Dimensional Heterostructures and Performance Regulation Descriptor for Electrocatalytic Ammonia Production from Nitric Oxide","authors":"Xingxing Wen, Oleg V. Prezhdo, Lai Xu","doi":"10.1021/jacs.5c02696","DOIUrl":"https://doi.org/10.1021/jacs.5c02696","url":null,"abstract":"The electrocatalytic reduction of nitric oxide (NO) to ammonia (NH<sub>3</sub>) represents an attractive alternative for valorizing waste NO streams (NORR). However, discovering efficient catalysts for NO-to-NH<sub>3</sub> conversion remains challenging. We have designed metal-intercalated twisted graphene-BN heterostructures, in which metal atoms act as electron-transfer bridges. The twisted configuration facilitates cross-interface charge transfer, redistributing electrons from the graphene–metal interface to the metal–BN interface and BN surface. This electronic modulation enables boron atom adjacent to the metal center in BN to serve as active sites, promoting strong chemisorption and enhanced activation of NO. After high-throughput screening of the stability and NO capture ability of various transition metal-intercalated twisted heterostructures, we have investigated systematically the NORR pathways across 30 candidates. The results show that the rBN-Ti-Gθ and rBN-V-Gθ heterostructures exhibit exceptional NO-to-NH<sub>3</sub> catalytic performance under optimized twisting conditions. Additionally, using sure independence screening and sparsifying operator (SISSO) for model training, we propose a descriptor and establish a relationship between the twist angle and catalytic activity. This study bridges the gap in applying twisted heterostructures to NORR electrocatalysis and provides new insights and strategies for designing high-performance NORR catalysts.","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":"4 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143841281","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Taehyun Kim, Taeseung Kim, Taegyoung Lee, Ye-Eun Park, Jeonghyun Kim, Seoungjae Kang, Hyerim Kim, Seokjae Hong, Naoki Matsui, Hyungsub Kim, Sangryun Kim
Hydride ion (H–)-conducting solid-state materials have lately received great attention for advanced electrochemical energy storage/conversion systems, including hydride ion-based batteries, electrolysis, and fuel cells. However, the highly reactive nature of hydride ions has posed challenges in diversifying anion systems, which are crucial for designing their effective transport. This study reports perovskite-type hydride ion conductors, Sr1–yNayLiH3–x–y(BH4)x (0 ≤ x ≤ 1 and 0 ≤ y ≤ 0.1), employing polyanionic borohydride (BH4–) as the anions in the structure. Structural characterization indicates that single-phase hydride ion conductors, in which H– and BH4– coexist in the cubic perovskite structure, are stabilized at the low-x region. In addition, incorporating H– vacancies (an increase in y) enhances the disorder of H– and BH4–, improving hydride ion conductivity by 3 orders of magnitude. Neutron powder diffraction analysis reveals that the polyanionic BH4– interacts asymmetrically with the cations (Sr2+ and Na+), thereby facilitating hydride ion conduction through pathways where these interactions are weaker. This unusual structure allows for a high hydride ion conductivity of over 10–4 S cm–1 at 100 °C. The current study suggests that many complex anions can be promising candidates as novel anion systems for hydride ion conductors.
{"title":"Hydride Ion Conductors with Polyanionic Complex Anions","authors":"Taehyun Kim, Taeseung Kim, Taegyoung Lee, Ye-Eun Park, Jeonghyun Kim, Seoungjae Kang, Hyerim Kim, Seokjae Hong, Naoki Matsui, Hyungsub Kim, Sangryun Kim","doi":"10.1021/jacs.4c17532","DOIUrl":"https://doi.org/10.1021/jacs.4c17532","url":null,"abstract":"Hydride ion (H<sup>–</sup>)-conducting solid-state materials have lately received great attention for advanced electrochemical energy storage/conversion systems, including hydride ion-based batteries, electrolysis, and fuel cells. However, the highly reactive nature of hydride ions has posed challenges in diversifying anion systems, which are crucial for designing their effective transport. This study reports perovskite-type hydride ion conductors, Sr<sub>1–<i>y</i></sub>Na<sub><i>y</i></sub>LiH<sub>3–<i>x</i>–<i>y</i></sub>(BH<sub>4</sub>)<sub><i>x</i></sub> (0 ≤ <i>x</i> ≤ 1 and 0 ≤ <i>y</i> ≤ 0.1), employing polyanionic borohydride (BH<sub>4</sub><sup>–</sup>) as the anions in the structure. Structural characterization indicates that single-phase hydride ion conductors, in which H<sup>–</sup> and BH<sub>4</sub><sup>–</sup> coexist in the cubic perovskite structure, are stabilized at the low-<i>x</i> region. In addition, incorporating H<sup>–</sup> vacancies (an increase in <i>y</i>) enhances the disorder of H<sup>–</sup> and BH<sub>4</sub><sup>–</sup>, improving hydride ion conductivity by 3 orders of magnitude. Neutron powder diffraction analysis reveals that the polyanionic BH<sub>4</sub><sup>–</sup> interacts asymmetrically with the cations (Sr<sup>2+</sup> and Na<sup>+</sup>), thereby facilitating hydride ion conduction through pathways where these interactions are weaker. This unusual structure allows for a high hydride ion conductivity of over 10<sup>–4</sup> S cm<sup>–1</sup> at 100 °C. The current study suggests that many complex anions can be promising candidates as novel anion systems for hydride ion conductors.","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":"9 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143846769","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Deracemization of C(sp3)–H arylated carbonyl compounds faces limitations in terms of substrate scope. Through the photoactivation of the aryl group and the stereocontrol of the generated arene radical cation via asymmetric ion-pairing catalysis, we are able to achieve deracemization of carbonyl compounds arylated at both enolizable and unenolizable stereocenters. A diverse range of α-, β-, and γ-aryl ketones and esters, including natural products and medicinal derivatives, can be effectively converted into their enantiomers with high enantioselectivity. Mechanistic investigations through combined experimental and computational studies suggest that the reaction involves single-electron oxidation of electron-rich aryl groups, followed by a kinetic resolution of the resulting radical cation intermediates by the chiral phosphate anion. Deprotonation is identified as the stereodetermining step, while stereoselective back electron transfer and triplet-state quenching of 3 Mes-Acr1+* may also affect the enantioselectivity at the photostationary state.
{"title":"Deracemization of C(sp3)–H Arylated Carbonyl Compounds via Asymmetric Ion-Pairing Photoredox Catalysis","authors":"Chenxi Wen, Zhengke Huang, Sheng-Ye Zhang, Zhimin Li, Bolong Chai, Zheng Huang, Qi-Kai Kang","doi":"10.1021/jacs.5c02235","DOIUrl":"https://doi.org/10.1021/jacs.5c02235","url":null,"abstract":"Deracemization of C(sp<sup>3</sup>)–H arylated carbonyl compounds faces limitations in terms of substrate scope. Through the photoactivation of the aryl group and the stereocontrol of the generated arene radical cation via asymmetric ion-pairing catalysis, we are able to achieve deracemization of carbonyl compounds arylated at both enolizable and unenolizable stereocenters. A diverse range of α-, β-, and γ-aryl ketones and esters, including natural products and medicinal derivatives, can be effectively converted into their enantiomers with high enantioselectivity. Mechanistic investigations through combined experimental and computational studies suggest that the reaction involves single-electron oxidation of electron-rich aryl groups, followed by a kinetic resolution of the resulting radical cation intermediates by the chiral phosphate anion. Deprotonation is identified as the stereodetermining step, while stereoselective back electron transfer and triplet-state quenching of <sup>3</sup> Mes-Acr<sub>1</sub><sup>+</sup>* may also affect the enantioselectivity at the photostationary state.","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":"16 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143846779","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The advancement of robust synthetic methodologies for generating fluorinated quaternary carbon chiral centers is highly sought after in the fields of organic and medicinal chemistry. This study successfully provides such compounds through cobalt-catalyzed asymmetric Negishi coupling reactions of α-bromo-α-fluoro ketones with aryl/alkenyl zinc reagents. The adjustment of chiral unsymmetric N,N,N-tridentate (CUT) ligands played a key role in improving reactivity and selectivity in the cobalt catalysis, preventing the formation of hydrodebromination byproducts, and accommodating sterically hindered substrates and heterocycles. Control and kinetic experiments reveal that transmetalation serves as the rate-limiting step, a mechanistic characteristic that sets the newly developed asymmetric cobalt-catalyzed cross-couplings apart from previous methodologies.
{"title":"Asymmetric Cobalt Catalysis for the Construction of Quaternary Stereogenic Centers with Fluorine Atoms","authors":"Jingyi Wang, Jin Yang, Jian He, Zhan Lu","doi":"10.1021/jacs.5c03944","DOIUrl":"https://doi.org/10.1021/jacs.5c03944","url":null,"abstract":"The advancement of robust synthetic methodologies for generating fluorinated quaternary carbon chiral centers is highly sought after in the fields of organic and medicinal chemistry. This study successfully provides such compounds through cobalt-catalyzed asymmetric Negishi coupling reactions of α-bromo-α-fluoro ketones with aryl/alkenyl zinc reagents. The adjustment of chiral unsymmetric <i>N</i>,<i>N</i>,<i>N</i>-tridentate (CUT) ligands played a key role in improving reactivity and selectivity in the cobalt catalysis, preventing the formation of hydrodebromination byproducts, and accommodating sterically hindered substrates and heterocycles. Control and kinetic experiments reveal that transmetalation serves as the rate-limiting step, a mechanistic characteristic that sets the newly developed asymmetric cobalt-catalyzed cross-couplings apart from previous methodologies.","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":"108 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143846475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Advancements in molecular electronics focus on single molecules as key components to create stable and functional devices that meet the requirements of device miniaturization and molecular function exploration. However, as the pioneering concept of a molecular diode, all single-molecule rectifiers reported previously are limited by their modest rectification ratios, owing to electron transmission in the off-state, highlighting the imperative for performance enhancements. Here, we demonstrate a unique method capable of realizing a stable and reproducible high-performance single-molecule rectifier through the strategic application of an electric-field-catalyzed Fries rearrangement. This flexible reaction enables the exquisite control of reversible conductance switching between a structure with constructive quantum interference and a structure with destructive quantum interference, therefore leading to an exceptional rectification ratio of up to 5000 at a bias of 1.0 V, which ranks the highest among the rectifiers constructed by only one individual molecule. The stable operation of nearly 100 devices at high temperatures demonstrates reproducibility. Moreover, on-chip integration of different single-molecule rectifiers succeeds in achieving half-wave and bridge rectifications, thus facilitating efficient alternating current-to-direct current conversions. This convenient strategy of electric-field-catalyzed quantum interference switching potentially revolutionizes device efficiency and miniaturization in nanotechnology, laying an actual step toward future practical integrated molecular-scale electronic nanocircuits.
{"title":"A Robust Single-Molecule Diode with High Rectification Ratio and Integrability","authors":"Yilin Guo, Chen Yang, Shuyao Zhou, Kendall N. Houk, Xuefeng Guo","doi":"10.1021/jacs.5c00566","DOIUrl":"https://doi.org/10.1021/jacs.5c00566","url":null,"abstract":"Advancements in molecular electronics focus on single molecules as key components to create stable and functional devices that meet the requirements of device miniaturization and molecular function exploration. However, as the pioneering concept of a molecular diode, all single-molecule rectifiers reported previously are limited by their modest rectification ratios, owing to electron transmission in the off-state, highlighting the imperative for performance enhancements. Here, we demonstrate a unique method capable of realizing a stable and reproducible high-performance single-molecule rectifier through the strategic application of an electric-field-catalyzed Fries rearrangement. This flexible reaction enables the exquisite control of reversible conductance switching between a structure with constructive quantum interference and a structure with destructive quantum interference, therefore leading to an exceptional rectification ratio of up to 5000 at a bias of 1.0 V, which ranks the highest among the rectifiers constructed by only one individual molecule. The stable operation of nearly 100 devices at high temperatures demonstrates reproducibility. Moreover, on-chip integration of different single-molecule rectifiers succeeds in achieving half-wave and bridge rectifications, thus facilitating efficient alternating current-to-direct current conversions. This convenient strategy of electric-field-catalyzed quantum interference switching potentially revolutionizes device efficiency and miniaturization in nanotechnology, laying an actual step toward future practical integrated molecular-scale electronic nanocircuits.","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":"75 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143846771","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Haozheng Li, Hanna H. Cramer, Jose B. Roque, Carlota Odena, Alex M. Shimozono, Paul J. Chirik
The origin of the meta- and ortho-to-fluorine site-selectivity in the C(sp2)–H borylation of fluorinated arenes with B2Pin2 and HBPin promoted by pyridine(dicarbene)cobalt catalysts has been investigated. In situ generation of the cobalt(I)-boryl complex and treatment with three representative fluoroarenes established meta-selective C(sp2)–H oxidative addition to form predominantly the meta isomers of the corresponding cobalt(I)-aryl complexes. Attempts to observe or isolate the four-coordinate cobalt(I)-boryl complex yielded the cobalt-hydride dimer, [(iPrACNC)CoH]2, borohydride (iPrACNC)CoH2BPin, or diboryl hydride, (iPrACNC)CoH(BPin)2 depending on the amounts of B2Pin2 and HBPin present. The phosphite derivatives (iPrACNC)CoH(P(OiPr)3) and (iPrACNC)CoBPin(P(OiPr)3) were prepared and crystallographically characterized. In the catalytic borylation of 1,3-difluorobenzene, ortho-to-fluorine cobalt(I)-aryl and borohydride complexes were identified as resting states despite meta-to-fluorine borylation being the major product of catalysis. Deuterium kinetic isotope effects support irreversible but not turnover-limiting C(sp2)–H oxidative addition. Stoichiometric borylation of isolated cobalt(I)-aryl intermediates with B2Pin2 established that the meta-cobalt(I)-aryl was more reactive than the ortho-isomer and accounts for the observed cobalt(I)-aryl resting states. All cobalt(I)-aryl compounds reacted more quickly with HBPin. While ortho-cobalt(I)-aryl compounds yielded arylboronate products with high site-selectivity, meta-cobalt-aryl counterparts yielded a mixture of arylboronate isomers and free arene. Deuterium labeling experiments with DBPin confirmed that HBPin mediates reversible C(sp2)–H oxidative addition. Thus, the overall site-selectivity arises from two reinforcing effects: (i) kinetically meta-selective oxidative addition and (ii) faster reaction of the meta-cobalt-aryl isomer with B2Pin2. As B2Pin2 is converted to HBPin, C(sp2)–H reductive elimination competes against borylation of the meta-cobalt-aryl isomer, resulting in increased ortho-selective borylation.
{"title":"The Role of Boron Reagents in Determining the Site-Selectivity of Pyridine(dicarbene) Cobalt-Catalyzed C–H Borylation of Fluorinated Arenes","authors":"Haozheng Li, Hanna H. Cramer, Jose B. Roque, Carlota Odena, Alex M. Shimozono, Paul J. Chirik","doi":"10.1021/jacs.4c15596","DOIUrl":"https://doi.org/10.1021/jacs.4c15596","url":null,"abstract":"The origin of the <i>meta</i>- and <i>ortho</i>-to-fluorine site-selectivity in the C(sp<sup>2</sup>)–H borylation of fluorinated arenes with B<sub>2</sub>Pin<sub>2</sub> and HBPin promoted by pyridine(dicarbene)cobalt catalysts has been investigated. <i>In situ</i> generation of the cobalt(I)-boryl complex and treatment with three representative fluoroarenes established <i>meta</i>-selective C(sp<sup>2</sup>)–H oxidative addition to form predominantly the <i>meta</i> isomers of the corresponding cobalt(I)-aryl complexes. Attempts to observe or isolate the four-coordinate cobalt(I)-boryl complex yielded the cobalt-hydride dimer, <b>[(</b><sup><b>iPr</b></sup><b>ACNC)CoH]</b><sub><b>2</b></sub>, borohydride <b>(</b><sup><b>iPr</b></sup><b>ACNC)CoH</b><sub><b>2</b></sub><b>BPin</b>, or diboryl hydride, <b>(</b><sup><b>iPr</b></sup><b>ACNC)CoH(BPin)</b><sub><b>2</b></sub> depending on the amounts of B<sub>2</sub>Pin<sub>2</sub> and HBPin present. The phosphite derivatives <b>(</b><sup><b>iPr</b></sup><b>ACNC)CoH(P(O</b><sup><b>i</b></sup><b>Pr)</b><sub><b>3</b></sub><b>)</b> and <b>(</b><sup><b>iPr</b></sup><b>ACNC)CoBPin(P(O</b><sup><b>i</b></sup><b>Pr)</b><sub><b>3</b></sub><b>)</b> were prepared and crystallographically characterized. In the catalytic borylation of 1,3-difluorobenzene, <i>ortho</i>-to-fluorine cobalt(I)-aryl and borohydride complexes were identified as resting states despite <i>meta</i>-to-fluorine borylation being the major product of catalysis. Deuterium kinetic isotope effects support irreversible but not turnover-limiting C(sp<sup>2</sup>)–H oxidative addition. Stoichiometric borylation of isolated cobalt(I)-aryl intermediates with B<sub>2</sub>Pin<sub>2</sub> established that the <i>meta-</i>cobalt(I)-aryl was more reactive than the <i>ortho-</i>isomer and accounts for the observed cobalt(I)-aryl resting states. All cobalt(I)-aryl compounds reacted more quickly with HBPin. While <i>ortho</i>-cobalt(I)-aryl compounds yielded arylboronate products with high site-selectivity, <i>meta</i>-cobalt-aryl counterparts yielded a mixture of arylboronate isomers and free arene. Deuterium labeling experiments with DBPin confirmed that HBPin mediates reversible C(sp<sup>2</sup>)–H oxidative addition. Thus, the overall site-selectivity arises from two reinforcing effects: (<i>i</i>) kinetically <i>meta-</i>selective oxidative addition and (<i>ii</i>) faster reaction of the <i>meta</i>-cobalt-aryl isomer with B<sub>2</sub>Pin<sub>2</sub>. As B<sub>2</sub>Pin<sub>2</sub> is converted to HBPin, C(sp<sup>2</sup>)–H reductive elimination competes against borylation of the <i>meta</i>-cobalt-aryl isomer, resulting in increased <i>ortho</i>-selective borylation.","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":"29 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143841277","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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