Yulin Deng, Xiaoyong Mo, Samuel Kin-Man Lai, Shu-Chih Haw, Ho Yu Au-Yeung, Edmund C. M. Tse
Electrocatalytic nitrate reduction reaction (NO3RR) for the selective generation of ammonia (NH3) enables the removal of deleterious nitrate pollutants while simultaneously upcycling them into a value-added fertilizer. The development of nonprecious metal-derived catalysts such as those featuring copper (Cu) as earth-abundant alternatives for the state-of-the-art precious metal catalysts is of urgent need yet suffering from the activity–selectivity–durability trilemma. Rational design of molecular Cu complexes with well-defined coordination structures permitting systematic structure–activity relationship (SAR) investigations is key to addressing the challenge. Here, a series of molecular Cu(I) complexes with [2]catenane ligands are developed as NO3RR electrocatalysts for the first time. By engineering multiple cationic ammoniums on the catenane backbone, acceptance of the anionic nitrate substrate as well as the release of the cationic ammonium product are promoted, thereby facilitating a higher Faradaic efficiency and product selectivity toward ammonia via an 8e– pathway. Of note, the mutual Coulombic repulsion between the multiply charged ligands is overcome by the mechanical interlocking such that the catalyst integrity can be maintained under practical conditions. This report highlights the promise of employing mechanically interlocked ligands as a platform for customizing metal complexes as catalysts for redox processes involving multiple proton-coupled electron transfer steps.
{"title":"Mechanical and Covalent Tailoring of Copper Catenanes for Selective Aqueous Nitrate-to-Ammonia Electrocatalysis","authors":"Yulin Deng, Xiaoyong Mo, Samuel Kin-Man Lai, Shu-Chih Haw, Ho Yu Au-Yeung, Edmund C. M. Tse","doi":"10.1021/jacs.4c18547","DOIUrl":"https://doi.org/10.1021/jacs.4c18547","url":null,"abstract":"Electrocatalytic nitrate reduction reaction (NO<sub>3</sub>RR) for the selective generation of ammonia (NH<sub>3</sub>) enables the removal of deleterious nitrate pollutants while simultaneously upcycling them into a value-added fertilizer. The development of nonprecious metal-derived catalysts such as those featuring copper (Cu) as earth-abundant alternatives for the state-of-the-art precious metal catalysts is of urgent need yet suffering from the activity–selectivity–durability trilemma. Rational design of molecular Cu complexes with well-defined coordination structures permitting systematic structure–activity relationship (SAR) investigations is key to addressing the challenge. Here, a series of molecular Cu(I) complexes with [2]catenane ligands are developed as NO<sub>3</sub>RR electrocatalysts for the first time. By engineering multiple cationic ammoniums on the catenane backbone, acceptance of the anionic nitrate substrate as well as the release of the cationic ammonium product are promoted, thereby facilitating a higher Faradaic efficiency and product selectivity toward ammonia via an 8e<sup>–</sup> pathway. Of note, the mutual Coulombic repulsion between the multiply charged ligands is overcome by the mechanical interlocking such that the catalyst integrity can be maintained under practical conditions. This report highlights the promise of employing mechanically interlocked ligands as a platform for customizing metal complexes as catalysts for redox processes involving multiple proton-coupled electron transfer steps.","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":"19 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2025-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143858131","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}
Syamasrit Dash, Arnaud Fihey, Ludovic Favereau, Corinne Lagrost, Rajaa Benchouaia, Sébastien Blanchard, Mickaël Ménand, Stéphane Le Gac
The efficient control of the chirality of Möbius π systems remains a challenging task that hinders the development of such molecules into information processing systems. Achieving such control through a redox process would thus open new opportunities. In this context, redox behaviors of Ni(II) and Pd(II) complexes of a Möbius aromatic [28]hexaphyrin doubly linked to an α-cyclodextrin have been investigated. This totemic architecture embedding three types of chirality elements generates two pseudoenantiomers after coordination with either metal. These isomeric pairs possess marked and opposite chiroptical signatures resulting from the P and M configurations of the Möbius π systems. Chemical oxidation to 26-π systems led to behaviors reminiscent to The Oak and the Reeds fable, due to a N3C coordination sphere of Ni(II) being more robust than that of Pd(II). Oxidized Ni(II) complexes (the Oak) maintain a Möbius-type conformation at the expense of the π-systems, which undergo an interruption due to inevitable water insertion. In contrast, oxidation of Pd(II) complexes (the Reeds) converts the Möbius aromatic systems into Hückel (rectangular) aromatic ones that are maintained in the chiral environment provided by the linking pattern with the cyclodextrin. This constitutes an effective chiral instructing site, as reduction back to their original Möbius configuration occurs with high stereoselectivity. Such a reversible shape-shifting process corresponds to a chiral memory phenomenon where the handedness of a cyclic π system is encoded in a scaffold and expressed upon changing an electronic state. For both metals, spectroelectrochemical studies ultimately revealed robust ON-OFF chiroptical switches, which is unprecedented with Möbius π-systems.
{"title":"Encoding and Expressing the Handedness of a Möbius π System in a Totemic Architecture","authors":"Syamasrit Dash, Arnaud Fihey, Ludovic Favereau, Corinne Lagrost, Rajaa Benchouaia, Sébastien Blanchard, Mickaël Ménand, Stéphane Le Gac","doi":"10.1021/jacs.5c00524","DOIUrl":"https://doi.org/10.1021/jacs.5c00524","url":null,"abstract":"The efficient control of the chirality of Möbius π systems remains a challenging task that hinders the development of such molecules into information processing systems. Achieving such control through a redox process would thus open new opportunities. In this context, redox behaviors of Ni(II) and Pd(II) complexes of a Möbius aromatic [28]hexaphyrin doubly linked to an α-cyclodextrin have been investigated. This totemic architecture embedding three types of chirality elements generates two pseudoenantiomers after coordination with either metal. These isomeric pairs possess marked and opposite chiroptical signatures resulting from the <i>P</i> and <i>M</i> configurations of the Möbius π systems. Chemical oxidation to 26-π systems led to behaviors reminiscent to <i>The Oak and the Reeds</i> fable, due to a N3C coordination sphere of Ni(II) being more robust than that of Pd(II). Oxidized Ni(II) complexes (<i>the Oak</i>) maintain a Möbius-type conformation at the expense of the π-systems, which undergo an interruption due to inevitable water insertion. In contrast, oxidation of Pd(II) complexes (<i>the Reeds</i>) converts the Möbius aromatic systems into Hückel (rectangular) aromatic ones that are maintained in the chiral environment provided by the linking pattern with the cyclodextrin. This constitutes an effective chiral instructing site, as reduction back to their original Möbius configuration occurs with high stereoselectivity. Such a reversible shape-shifting process corresponds to a chiral memory phenomenon where the handedness of a cyclic π system is encoded in a scaffold and expressed upon changing an electronic state. For both metals, spectroelectrochemical studies ultimately revealed robust ON-OFF chiroptical switches, which is unprecedented with Möbius π-systems.","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":"38 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2025-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143858132","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}
Higher viscosity typically slows chemical reactions by restricting molecular movement, while stirring accelerates reactions by enhancing reactant diffusion and collisions. However, in this study, we reveal that reaction rates in nanowire dispersions─with microscopic viscosity ∼300 times that of decane, can be enhanced by over an order of magnitude. Counterintuitively, stirring slows the reaction with higher stirring rates causing even greater deceleration. This phenomenon is observed in both photo- and thermally activated cyclic reactions. Molecular dynamics simulations and confocal laser scanning microscopy suggest that aliphatic chains grafted onto nanowires interact with anisotropic molecules, increasing their local concentrations near the nanowires. Notably, azobenzene photoisomerization is completely inhibited in the nanowire dispersion, despite completing within 30 s in the absence of nanowires. We propose that the aliphatic chains align reactive molecules directionally, while the confined space prevents bulky cis-isomer formation. These findings show that nanowires not only harvest and orient reactive molecules but also exclude bulky products, significantly enhancing the reaction kinetics in confined systems.
{"title":"Boosting Reaction Kinetics with Viscous Nanowire Dispersions","authors":"Jurong Dong, Hongkun Cao, Zhiwei Yang, Zongze Zhang, Zhijie Yang, Lingxiang Jiang, Jingjing Wei","doi":"10.1021/jacs.5c02034","DOIUrl":"https://doi.org/10.1021/jacs.5c02034","url":null,"abstract":"Higher viscosity typically slows chemical reactions by restricting molecular movement, while stirring accelerates reactions by enhancing reactant diffusion and collisions. However, in this study, we reveal that reaction rates in nanowire dispersions─with microscopic viscosity ∼300 times that of decane, can be enhanced by over an order of magnitude. Counterintuitively, stirring slows the reaction with higher stirring rates causing even greater deceleration. This phenomenon is observed in both photo- and thermally activated cyclic reactions. Molecular dynamics simulations and confocal laser scanning microscopy suggest that aliphatic chains grafted onto nanowires interact with anisotropic molecules, increasing their local concentrations near the nanowires. Notably, azobenzene photoisomerization is completely inhibited in the nanowire dispersion, despite completing within 30 s in the absence of nanowires. We propose that the aliphatic chains align reactive molecules directionally, while the confined space prevents bulky <i>cis</i>-isomer formation. These findings show that nanowires not only harvest and orient reactive molecules but also exclude bulky products, significantly enhancing the reaction kinetics in confined systems.","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":"11 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2025-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143858149","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}
Sintering of supported metal nanoparticles (NPs) is a general and important phenomenon in materials and catalysis science. A consensus view is that it takes place either via the Ostwald ripening (OR) or particle migration and coalescence (PMC) mechanism through the substrate, but how sintering occurs under high gas pressure and high temperature has not been addressed. Here, we perform millisecond-scale environmental kinetic Monte Carlo (EKMC) simulations combined with density functional theory (DFT) calculations to reveal a unique through-space sintering mechanism, particle hopping and coalescence (PHC). Under high CO pressure and high temperature, the coalescence of Au NPs takes place through NP hopping up from the anatase TiO2(101) substrate and mass transfer via the gas phase. When the sintered floating NP reaches a critical size, it spontaneously redeposits onto the substrate. This process is driven by the preference of interfacial Au atoms of small NPs to interact with CO rather than the substrate at a high CO chemical potential. The PHC mechanism implies that NP sintering and intersubstrate catalyst transfer may occur easier than expected during reactions and provides a distinct perspective to understand catalyst thermal deactivation under harsh operando conditions.
{"title":"Particle Hopping and Coalescence of Supported Au Nanoparticles in Harsh Reactive Environments","authors":"Shuoqi Zhang, Yu Han, Xiao-Yan Li, Qingli Tang, Beien Zhu, Yi Gao","doi":"10.1021/jacs.5c03633","DOIUrl":"https://doi.org/10.1021/jacs.5c03633","url":null,"abstract":"Sintering of supported metal nanoparticles (NPs) is a general and important phenomenon in materials and catalysis science. A consensus view is that it takes place either via the Ostwald ripening (OR) or particle migration and coalescence (PMC) mechanism through the substrate, but how sintering occurs under high gas pressure and high temperature has not been addressed. Here, we perform millisecond-scale environmental kinetic Monte Carlo (EKMC) simulations combined with density functional theory (DFT) calculations to reveal a unique through-space sintering mechanism, particle hopping and coalescence (PHC). Under high CO pressure and high temperature, the coalescence of Au NPs takes place through NP hopping up from the anatase TiO<sub>2</sub>(101) substrate and mass transfer via the gas phase. When the sintered floating NP reaches a critical size, it spontaneously redeposits onto the substrate. This process is driven by the preference of interfacial Au atoms of small NPs to interact with CO rather than the substrate at a high CO chemical potential. The PHC mechanism implies that NP sintering and intersubstrate catalyst transfer may occur easier than expected during reactions and provides a distinct perspective to understand catalyst thermal deactivation under harsh operando conditions.","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":"43 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2025-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143858151","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}
Photochemical transformations continue to serve as powerful synthetic tools for rapid chemical synthesis and diversification. Recent developments in photoredox and photochemical reactivity have captured the attention of researchers in a wide array of disciplines, where many new applications of these reactions have been reported. We disclose the use of photochemical synthetic strategies as a modern approach to natural product synthesis that leverages the inherent reactivity of radicals as a platform for constructing complex scaffolds. We demonstrate this in an iterative photochemical synthesis, offering novel synthetic tactics, mild conditions, and operationally simple synthetic procedures to construct three stemoamide alkaloids in the shortest sequences to date. The key disconnection involves the use of both the oxidative and reductive capabilities of an acridinium photoredox catalyst to forge the densely functionalized tetrahydrofuran ring via a polar radical crossover cycloaddition. The resultant butyrolactone serves as a handle for a radical polar crossover cycloaddition to construct a unique oxaspirocyclic butenolide. Finally, a late-stage heteroarene transmutation provides a linchpin intermediate used to access three stemoamide alkaloids. The efficiency of these syntheses exemplifies the power of this approach while also demonstrating a departure from traditional disconnections and shedding light on a new type of synthetic art.
{"title":"Photochemically Enabled Total Syntheses of Stemoamide Alkaloids","authors":"Nicholas R. Akkawi, David A. Nicewicz","doi":"10.1021/jacs.5c01788","DOIUrl":"https://doi.org/10.1021/jacs.5c01788","url":null,"abstract":"Photochemical transformations continue to serve as powerful synthetic tools for rapid chemical synthesis and diversification. Recent developments in photoredox and photochemical reactivity have captured the attention of researchers in a wide array of disciplines, where many new applications of these reactions have been reported. We disclose the use of photochemical synthetic strategies as a modern approach to natural product synthesis that leverages the inherent reactivity of radicals as a platform for constructing complex scaffolds. We demonstrate this in an iterative photochemical synthesis, offering novel synthetic tactics, mild conditions, and operationally simple synthetic procedures to construct three stemoamide alkaloids in the shortest sequences to date. The key disconnection involves the use of both the oxidative and reductive capabilities of an acridinium photoredox catalyst to forge the densely functionalized tetrahydrofuran ring via a polar radical crossover cycloaddition. The resultant butyrolactone serves as a handle for a radical polar crossover cycloaddition to construct a unique oxaspirocyclic butenolide. Finally, a late-stage heteroarene transmutation provides a linchpin intermediate used to access three stemoamide alkaloids. The efficiency of these syntheses exemplifies the power of this approach while also demonstrating a departure from traditional disconnections and shedding light on a new type of synthetic art.","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":"8 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2025-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143858157","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}
This Correction reports recent discoveries on the synthesis, stability, and performance of compound <b>2′</b> as a surface-cross-linker in the article. The corrections do not alter the conclusions of the work. Compound <b>2′</b> instead of <b>2</b> (which contains a vicinal diol) was used as the surface-cross-linker in the preparation of carbohydrate-binding molecularly imprinted nanoparticles (MINPs). This was done to avoid potential competition between the sugar template and <b>2</b> for the boroxole functional monomer <b>4</b> in the formation of the template–functional complex (e.g., <b>5</b>). Compound <b>2</b> was recently found to afford carbohydrate-binding MINPs equally well as <b>2′</b>. The suspected boronate formation between <b>2</b> and <b>4</b>, hence, was negligible during the MINP preparation, likely due to different hydrophobicities of <b>5</b> and <b>2</b> that made them prefer different locations in the micelles. Separately, compound <b>2′</b> was discovered to undergo decomposition slowly during storage through a cleavage at the ammonium headgroup to afford tris(2-azidoethyl)amine. Thus, the previously reported <b>2′</b> was a cross-linker mixture with different purities depending on the length of storage time. Further investigation revealed that freshly prepared and aged <b>2′</b> mixtures afforded MINPs with similar performance in their binding of carbohydrates. In addition, with an acidic group installed in the imprinted binding site, these MINPs also displayed similar performance in their catalytic hydrolysis of carbohydrates. Because <b>2′</b> and tris(2-azidoethyl)amine both contain three azido groups, they both can cross-link the micelles. This is likely the reason why MINPs prepared with different compositions of <b>2′</b> and tris(2-azidoethyl)amine performed similarly. The above findings are added to the updated Supporting Information. The new Supporting Information file also corrected mistakes found in the original Supporting Information, where wrong NMR spectra were used for comparison in the MINP preparation. Two typical comparisons are shown in the updated Supporting Information (Figures 1S and 25S for monosaccharide-binding and oligosaccharide-binding MINPs, respectively). They replace Figures 1S and 25S in the previous Supporting Information. Previous comparisons shown in Figures 4S, 7S, 10S, 13S, 16S, 19S, 22S, 28S, 31S, 34S, 37S, 40S, 43S, 46S, 49S, 52S, 55S, and 58S are removed. The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/jacs.5c03991. Experimental details, ITC titration curves, and additional data (PDF) Correction to “AGeneral Method for SelectiveRecognition of Monosaccharides and Oligosaccharides in Water” <span> 0 </span><span> views </span> <span> 0 </span><span> shares </span> <span> 0 </span><span> downloads </span> Most electronic Supporting Information files are available without a subscription to ACS Web Editions. Such files may be downloaded by arti
{"title":"Correction to “A General Method for Selective Recognition of Monosaccharides and Oligosaccharides in Water”","authors":"Roshan W. Gunasekara, Yan Zhao","doi":"10.1021/jacs.5c03991","DOIUrl":"https://doi.org/10.1021/jacs.5c03991","url":null,"abstract":"This Correction reports recent discoveries on the synthesis, stability, and performance of compound <b>2′</b> as a surface-cross-linker in the article. The corrections do not alter the conclusions of the work. Compound <b>2′</b> instead of <b>2</b> (which contains a vicinal diol) was used as the surface-cross-linker in the preparation of carbohydrate-binding molecularly imprinted nanoparticles (MINPs). This was done to avoid potential competition between the sugar template and <b>2</b> for the boroxole functional monomer <b>4</b> in the formation of the template–functional complex (e.g., <b>5</b>). Compound <b>2</b> was recently found to afford carbohydrate-binding MINPs equally well as <b>2′</b>. The suspected boronate formation between <b>2</b> and <b>4</b>, hence, was negligible during the MINP preparation, likely due to different hydrophobicities of <b>5</b> and <b>2</b> that made them prefer different locations in the micelles. Separately, compound <b>2′</b> was discovered to undergo decomposition slowly during storage through a cleavage at the ammonium headgroup to afford tris(2-azidoethyl)amine. Thus, the previously reported <b>2′</b> was a cross-linker mixture with different purities depending on the length of storage time. Further investigation revealed that freshly prepared and aged <b>2′</b> mixtures afforded MINPs with similar performance in their binding of carbohydrates. In addition, with an acidic group installed in the imprinted binding site, these MINPs also displayed similar performance in their catalytic hydrolysis of carbohydrates. Because <b>2′</b> and tris(2-azidoethyl)amine both contain three azido groups, they both can cross-link the micelles. This is likely the reason why MINPs prepared with different compositions of <b>2′</b> and tris(2-azidoethyl)amine performed similarly. The above findings are added to the updated Supporting Information. The new Supporting Information file also corrected mistakes found in the original Supporting Information, where wrong NMR spectra were used for comparison in the MINP preparation. Two typical comparisons are shown in the updated Supporting Information (Figures 1S and 25S for monosaccharide-binding and oligosaccharide-binding MINPs, respectively). They replace Figures 1S and 25S in the previous Supporting Information. Previous comparisons shown in Figures 4S, 7S, 10S, 13S, 16S, 19S, 22S, 28S, 31S, 34S, 37S, 40S, 43S, 46S, 49S, 52S, 55S, and 58S are removed. The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/jacs.5c03991. Experimental details, ITC titration curves, and additional data (PDF) Correction to “A\u0000General Method for Selective\u0000Recognition of Monosaccharides and Oligosaccharides in Water” <span> 0 </span><span> views </span> <span> 0 </span><span> shares </span> <span> 0 </span><span> downloads </span> Most electronic Supporting Information files are available without a subscription to ACS Web Editions. Such files may be downloaded by arti","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":"33 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2025-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143858153","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}
Hope A. Long, Daniel Duong, Joanna Blawat, Gregory Morrison, Yan Wu, Huibo Cao, Nabaraj Pokhrel, David S. Parker, John Singleton, Rongying Jin, Vladislav V. Klepov
HfCuSi2-type pnictogen compounds have recently been shown to be a versatile platform for designing materials with topologically nontrivial band structures. However, these phases require strict control over the electron count to tune the Fermi level, which can only be achieved in compositions with A2+M2+Pn2 and A3+M+Pn2 (A = lanthanides, M = transition metals, Pn = pnictogens P–Bi) charge distribution. While such lanthanide compounds have been thoroughly studied as candidate magnetic topological materials, their heavy element analogs with uranium and bismuth remain largely underexplored. In this report, we present the synthesis of UCuxBi2 single crystals and study their magnetic properties. Detailed structural analysis revealed that flux-grown crystals always form as a site-deficient UCuxBi2 composition, where x varies between 0.20 and 0.64. Magnetic property measurements revealed a dependence of the magnetic coupling on the Cu site deficiency, linearly changing the Néel temperature from 51 K for UCu0.60Bi2 to 118 K for UCu0.30Bi2. Moreover, higher Cu concentration promotes a metamagnetic transition in highly magnetically anisotropic UCu0.60Bi2 single crystals. We show that DFT calculations can successfully model site deficiency in the UCuxSb2 and UCuxBi2 systems. This work paves the way toward using the site deficiency to tune the Fermi level in more ubiquitous A3+M2+xPn2 phases, which previously have not been considered topological candidate materials due to unfavorable electron count.
{"title":"Magnetic Properties Tuning via Broad Range Site Deficiency in Square Net Material UCuxBi2","authors":"Hope A. Long, Daniel Duong, Joanna Blawat, Gregory Morrison, Yan Wu, Huibo Cao, Nabaraj Pokhrel, David S. Parker, John Singleton, Rongying Jin, Vladislav V. Klepov","doi":"10.1021/jacs.4c18438","DOIUrl":"https://doi.org/10.1021/jacs.4c18438","url":null,"abstract":"HfCuSi<sub>2</sub>-type pnictogen compounds have recently been shown to be a versatile platform for designing materials with topologically nontrivial band structures. However, these phases require strict control over the electron count to tune the Fermi level, which can only be achieved in compositions with A<sup>2+</sup>M<sup>2+</sup>Pn<sub>2</sub> and A<sup>3+</sup>M<sup>+</sup>Pn<sub>2</sub> (A = lanthanides, M = transition metals, Pn = pnictogens P–Bi) charge distribution. While such lanthanide compounds have been thoroughly studied as candidate magnetic topological materials, their heavy element analogs with uranium and bismuth remain largely underexplored. In this report, we present the synthesis of UCu<sub><i>x</i></sub>Bi<sub>2</sub> single crystals and study their magnetic properties. Detailed structural analysis revealed that flux-grown crystals always form as a site-deficient UCu<sub><i>x</i></sub>Bi<sub>2</sub> composition, where <i>x</i> varies between 0.20 and 0.64. Magnetic property measurements revealed a dependence of the magnetic coupling on the Cu site deficiency, linearly changing the Néel temperature from 51 K for UCu<sub>0.60</sub>Bi<sub>2</sub> to 118 K for UCu<sub>0.30</sub>Bi<sub>2</sub>. Moreover, higher Cu concentration promotes a metamagnetic transition in highly magnetically anisotropic UCu<sub>0.60</sub>Bi<sub>2</sub> single crystals. We show that DFT calculations can successfully model site deficiency in the UCu<sub><i>x</i></sub>Sb<sub>2</sub> and UCu<sub><i>x</i></sub>Bi<sub>2</sub> systems. This work paves the way toward using the site deficiency to tune the Fermi level in more ubiquitous A<sup>3+</sup>M<sup>2+</sup><sub><i>x</i></sub>Pn<sub>2</sub> phases, which previously have not been considered topological candidate materials due to unfavorable electron count.","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":"33 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2025-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143858128","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}
Frustrated Lewis pairs (FLPs) have been widely utilized as useful reagents and catalysts for activation of small molecules (SMs) through thermally controlled equilibrium formation of FLP–SM adducts. Herein, we report a light- and heat-responsive FLP system for on-demand fixation of ethylene. The system realizes capture and release of ethylene orthogonally triggered by visible light and heat, demonstrating potential utility as a nonmetallic and environmentally benign method for separation and storage of ethylene. The applicability to other alkenes is also demonstrated. Mechanistic investigations clarify that the photoexcited FLP enables stepwise radical addition to ethylene, followed by skeletal rearrangement to afford the FLP–ethylene adduct, which undergoes thermally promoted, concerted retro-cycloaddition to release ethylene and the free FLP. As a synthetic application, nonequilibrium, selective cis-to-trans isomerization of cyclooctene is achieved through the capture and release of cyclooctene with the FLP. This work discloses unique photochemical reactivity and application of FLPs, leading to further expansion of FLP chemistry into chemical science.
{"title":"Light- and Heat-Responsive Frustrated Lewis Pair Enables On-Demand Fixation of Ethylene","authors":"Taiki Yanagi, Jun Takaya","doi":"10.1021/jacs.5c03130","DOIUrl":"https://doi.org/10.1021/jacs.5c03130","url":null,"abstract":"Frustrated Lewis pairs (FLPs) have been widely utilized as useful reagents and catalysts for activation of small molecules (SMs) through thermally controlled equilibrium formation of FLP–SM adducts. Herein, we report a light- and heat-responsive FLP system for on-demand fixation of ethylene. The system realizes capture and release of ethylene orthogonally triggered by visible light and heat, demonstrating potential utility as a nonmetallic and environmentally benign method for separation and storage of ethylene. The applicability to other alkenes is also demonstrated. Mechanistic investigations clarify that the photoexcited FLP enables stepwise radical addition to ethylene, followed by skeletal rearrangement to afford the FLP–ethylene adduct, which undergoes thermally promoted, concerted <i>retro</i>-cycloaddition to release ethylene and the free FLP. As a synthetic application, nonequilibrium, selective <i>cis</i>-to-<i>trans</i> isomerization of cyclooctene is achieved through the capture and release of cyclooctene with the FLP. This work discloses unique photochemical reactivity and application of FLPs, leading to further expansion of FLP chemistry into chemical science.","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":"17 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2025-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143858156","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}
Changyu Liu, Kean Chen, Fumin Li, Along Zhao, Ping Liu, Zhongxue Chen, Yongjin Fang, Yuliang Cao
The alluaudite-type sulfate Na2Fe2(SO4)3 has gained significant attention as a promising cathode material for sodium-ion batteries (SIBs). However, the inevitable formation of impurities during synthesis and the irreversible structural distortion caused by Fe–Na exchange during electrochemical reactions severely hinder its electrochemical performance. Herein, we tackle these challenges by engineering an enlarged Fe–Fe distance in the lattice through partial PO43– substitution. This strategic modification significantly alleviates the Coulombic repulsion between Fe ions and effectively prevents Fe-migration during the electrochemical reaction. Moreover, the unique ion state within the structure ensures enhanced ion/electron transport kinetics, minimal volume change, and a stable framework conducive to long cycling life. Notably, the novel Fe-fully occupied phase-pure Na2.5Fe2(SO4)2.5(PO4)0.5 [also denoted as Na5Fe4(SO4)5(PO4)] electrode delivers a record-high discharge capacity of 112 mA h g–1 at 0.2C, coupled with exceptional cycling stability with 88.8% capacity retention over 10,000 cycles at 10C. Additionally, the enhanced adsorption energy of Na2.5Fe2(SO4)2.5(PO4)0.5 cathode toward H2O contributes to its outstanding air stability in humid atmosphere. This finding offers valuable insights for the development of advanced, low-cost materials for SIBs.
{"title":"Unlocking Phase Purity of Sodium Iron Sulfate for Low-Cost and High-Performance Sodium-Ion Batteries","authors":"Changyu Liu, Kean Chen, Fumin Li, Along Zhao, Ping Liu, Zhongxue Chen, Yongjin Fang, Yuliang Cao","doi":"10.1021/jacs.5c02485","DOIUrl":"https://doi.org/10.1021/jacs.5c02485","url":null,"abstract":"The alluaudite-type sulfate Na<sub>2</sub>Fe<sub>2</sub>(SO<sub>4</sub>)<sub>3</sub> has gained significant attention as a promising cathode material for sodium-ion batteries (SIBs). However, the inevitable formation of impurities during synthesis and the irreversible structural distortion caused by Fe–Na exchange during electrochemical reactions severely hinder its electrochemical performance. Herein, we tackle these challenges by engineering an enlarged Fe–Fe distance in the lattice through partial PO<sub>4</sub><sup>3–</sup> substitution. This strategic modification significantly alleviates the Coulombic repulsion between Fe ions and effectively prevents Fe-migration during the electrochemical reaction. Moreover, the unique ion state within the structure ensures enhanced ion/electron transport kinetics, minimal volume change, and a stable framework conducive to long cycling life. Notably, the novel Fe-fully occupied phase-pure Na<sub>2.5</sub>Fe<sub>2</sub>(SO<sub>4</sub>)<sub>2.5</sub>(PO<sub>4</sub>)<sub>0.5</sub> [also denoted as Na<sub>5</sub>Fe<sub>4</sub>(SO<sub>4</sub>)<sub>5</sub>(PO<sub>4</sub>)] electrode delivers a record-high discharge capacity of 112 mA h g<sup>–1</sup> at 0.2C, coupled with exceptional cycling stability with 88.8% capacity retention over 10,000 cycles at 10C. Additionally, the enhanced adsorption energy of Na<sub>2.5</sub>Fe<sub>2</sub>(SO<sub>4</sub>)<sub>2.5</sub>(PO<sub>4</sub>)<sub>0.5</sub> cathode toward H<sub>2</sub>O contributes to its outstanding air stability in humid atmosphere. This finding offers valuable insights for the development of advanced, low-cost materials for SIBs.","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":"91 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143858159","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}
Fang Li, Xingyu Tang, Yunfan Fei, Jie Zhang, Jie Liu, Puyi Lang, Guangwei Che, Zilin Zhao, Yuqing Zheng, Yuan Fang, Chen Li, Dexiang Gao, Xiao Dong, Takanori Hattori, Jun Abe, Ho-kwang Mao, Haiyan Zheng, Kuo Li
Graphane shares the same two-dimensional honeycomb structure of graphene, but its saturated carbon skeleton gives rise to a bandgap and therefore provides more possibilities for the development of novel carbon-based semiconductors. However, the hydrogenation of graphene usually leads to disordered and incompletely hydrogenated graphane, and the precise synthesis of graphane with a specific configuration is still very challenging. Here, we synthesized a crystalline graphane nanoribbon (GANR) via pressure-induced polymerization of 2,2′-bipyrazine (BPZ). By performing Rietveld refinement of in situ neutron diffraction data, nuclear magnetic resonance spectroscopy, infrared spectra, and theoretical calculation, we found that BPZ experienced Diels–Alder polymerization between the π···π stacked aromatic rings and formed extended boat-GANR structures with exceptional long-range order. The unreacted −C═N– groups bridge the two ends of the boat and are ready for further functionalization. The GANR has a bandgap of 2.25 eV, with booming photoelectric response (ION/IOFF = 18.8). Our work highlights that high-pressure topochemical polymerization is a promising method for the precise synthesis of graphane with specific structure and desired properties.
{"title":"Ordered Graphane Nanoribbons Synthesized via High-Pressure Diels–Alder Polymerization of 2,2′-Bipyrazine","authors":"Fang Li, Xingyu Tang, Yunfan Fei, Jie Zhang, Jie Liu, Puyi Lang, Guangwei Che, Zilin Zhao, Yuqing Zheng, Yuan Fang, Chen Li, Dexiang Gao, Xiao Dong, Takanori Hattori, Jun Abe, Ho-kwang Mao, Haiyan Zheng, Kuo Li","doi":"10.1021/jacs.5c03116","DOIUrl":"https://doi.org/10.1021/jacs.5c03116","url":null,"abstract":"Graphane shares the same two-dimensional honeycomb structure of graphene, but its saturated carbon skeleton gives rise to a bandgap and therefore provides more possibilities for the development of novel carbon-based semiconductors. However, the hydrogenation of graphene usually leads to disordered and incompletely hydrogenated graphane, and the precise synthesis of graphane with a specific configuration is still very challenging. Here, we synthesized a crystalline graphane nanoribbon (GANR) via pressure-induced polymerization of 2,2′-bipyrazine (BPZ). By performing Rietveld refinement of in situ neutron diffraction data, nuclear magnetic resonance spectroscopy, infrared spectra, and theoretical calculation, we found that BPZ experienced Diels–Alder polymerization between the π···π stacked aromatic rings and formed extended boat-GANR structures with exceptional long-range order. The unreacted −C═N– groups bridge the two ends of the boat and are ready for further functionalization. The GANR has a bandgap of 2.25 eV, with booming photoelectric response (<i>I</i><sub>ON</sub>/<i>I</i><sub>OFF</sub> = 18.8). Our work highlights that high-pressure topochemical polymerization is a promising method for the precise synthesis of graphane with specific structure and desired properties.","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":"128 8 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143853845","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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