Journal of the American Chemical Society最新文献

{"title":"Accelerated Continuous Flow Depolymerization of Poly(Methyl Methacrylate)","authors":"Katharina S. C. Jäger, Gayathri Dev Ammini, Pieter-Jan Voorter, Priya Subramanian, Anil Kumar, Athina Anastasaki, Tanja Junkers","doi":"10.1021/jacs.4c12455","DOIUrl":"https://doi.org/10.1021/jacs.4c12455","url":null,"abstract":"A continuous flow setup comprising an inline dialysis unit for immediate monomer removal is used for the depolymerization of poly(methyl methacrylate) (pMMA), synthesized via reversible addition–fragmentation chain transfer (RAFT) polymerization. The approach used allows one to carry out solution depolymerizations at much higher polymer content compared to batch processes while maintaining high depolymerization conversions. pMMA is efficiently depolymerized in the flow reactor, yielding up to 68% monomer recovery under catalyst-free reaction conditions at 160 °C, starting from a 1 molar repeat unit concentration, which is a 20-fold improvement compared to previous batch studies. This was achieved by using the inline dialysis to continuously remove monomer from the depolymerization solution and hence continuously shifting of the depolymerization equilibrium to the recycling side. Depolymerizations at various temperatures, starting polymer concentrations, and reactor setup modifications are investigated, clearly showing the highly advantageous effect of the monomer removal on the reaction. The employed approach represents a significant advancement toward the industrial feasibility of depolymerization of methacrylates by lowering the solvent use, expanding its temperature operation window, and bringing polymer contents to a practically relevant level.","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":"262 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142849522","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}

{"title":"Unraveling the Bonding and Aromaticity of Pentazole, Pentaphosphole, and Cyclopentadiene Anions: A Comprehensive Study","authors":"Shailja Jain, David Danovich, Slavko Radenković, Sason Shaik","doi":"10.1021/jacs.4c14515","DOIUrl":"https://doi.org/10.1021/jacs.4c14515","url":null,"abstract":"This study investigates π-delocalization, π-bonding situations, and aromaticity of the pentazolate anion ([cyclo-N₅^–], (<b>a</b>)), which was detected by Christe <i>et al.</i> in 2002. To gain a broader perspective, we investigated the iso-π-electronic species [cyclo-P₅^–] (<b>b</b>) and [cyclo-(CH)₅^–] (<b>c</b>). VB analyses reveal that the three studied molecules display significant resonance stabilization, as indicated by their high resonance energy values. A comprehensive analysis of aromaticity was conducted using electronic and magnetic aromaticity indices, revealing that all three anions exhibit strong π-aromaticity and relatively weak σ-aromaticity.","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":"55 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142858126","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}

{"title":"Mixed Ionic and Electronic Conductivity in a Tetrathiafulvalene-Phosphonate Metal–Organic Framework","authors":"Catarina Ribeiro, Bowen Tan, Flávio Figueira, Ricardo F. Mendes, Joaquín Calbo, Gonçalo Valente, Paula Escamilla, Filipe A. Almeida Paz, João Rocha, Mircea Dincă, Manuel Souto","doi":"10.1021/jacs.4c13792","DOIUrl":"https://doi.org/10.1021/jacs.4c13792","url":null,"abstract":"Mixed ionic-electronic conductors have great potential as materials for energy storage applications. However, despite their promising properties, only a handful of metal–organic frameworks (MOFs) provide efficient pathways for both ion and electron transport. This work reports a proton–electron dual-conductive MOF based on tetrathiafulvalene(TTF)-phosphonate linkers and lanthanum ions. The formation of regular, partially oxidized TTF stacks with short S···S interactions facilitates electron transport via a hopping mechanism, reporting a room-temperature conductivity of 7.2 × 10^–6 S cm^–1. Additionally, the material exhibits a proton conductivity of 4.9 × 10^–5 S cm^–1 at 95% relative humidity conditions due to the presence of free −POH groups, enabling efficient proton transport pathways. These results demonstrate the potential of integrating electroactive building blocks along with phosphonate groups toward the development of mixed ionic-electronic conductors.","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":"24 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142858127","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}

{"title":"Unraveling Hydration Shell Dynamics and Viscosity Effects Around Cyanamide Probes via 2D IR Spectroscopy","authors":"Christopher J. Mallon, Majid Hassani, Ellia H. Osofsky, Savannah B. Familo, Edward E. Fenlon, Matthew J. Tucker","doi":"10.1021/jacs.4c12716","DOIUrl":"https://doi.org/10.1021/jacs.4c12716","url":null,"abstract":"Hydration dynamics and solvent viscosity play critical roles in the structure and function of biomolecules. An overwhelming body of evidence suggests that protein and membrane fluctuations are closely linked to solvent fluctuations. While extensive research exists on the use of vibrational probes to detect local interactions and solvent dynamics, fewer studies have explored how the behavior of these reporters changes in response to bulk viscosity. To address this gap, two-dimensional infrared spectroscopy (2D IR) was employed in this study to investigate the ultrafast hydration dynamics around a cyanamide (NCN) probe attached to a nucleoside, deoxycytidine, in aqueous solutions with varying glycerol content. The use of a small vibrational probe on a targeted nucleic acid offers the potential to capture more localized hydration dynamics than alternative methods. The time scales for the frequency correlation decays were found to increase linearly with bulk viscosity, ranging from 0.9 to 11.4 ps over viscosities of 0.96–49.1 cP. Additionally, molecular dynamics (MD) simulations were performed to model the local hydration dynamics around the NCN probe. Interestingly, increasing the glycerol content did not significantly alter the hydration of the deoxycytidine. The MD simulations further suggested that the NCN probe’s frequency fluctuations were primarily influenced by the dynamics of water in the second solvation shell. Cage correlation functions, which measure the movement of water molecules in and out of the second solvation shell, exhibited decays that closely matched those of the frequency-fluctuation correlation function (FFCF). These findings offer new insights into hydration dynamics and the impact of viscosity on biological systems.","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":"86 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142858154","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}

{"title":"Late-Stage Reshaping of Phage-Displayed Libraries to Macrocyclic and Bicyclic Landscapes using a Multipurpose Linchpin","authors":"Kejia Yan, Mark Miskolzie, Fernando Banales Mejia, Chuanhao Peng, Arunika I. Ekanayake, Alexey Atrazhev, Jessica Cao, Dustin J. Maly, Ratmir Derda","doi":"10.1021/jacs.4c13561","DOIUrl":"https://doi.org/10.1021/jacs.4c13561","url":null,"abstract":"Genetically encoded libraries (GEL) are increasingly being used for the discovery of ligands for “undruggable” targets that cannot be addressed with small molecules. Foundational GEL platforms like phage-, yeast-, ribosome-, and mRNA-display have enabled the display of libraries composed of 20 natural amino acids (20AA). Unnatural amino acids (UAA) and chemical post-translational modification (cPTM) expanded GEL beyond the 20AA space to yield unnatural linear, cyclic, and bicyclic peptides. The standard operating procedure incorporates UAA and cPTM into a “naive” library with 10⁸–10¹² compounds and uses a chemically upgraded library in multiple rounds of selection to discover target-binding hits. However, such an approach uses zero knowledge of natural peptide-receptor interactions that might have been discovered in selections performed with 20AA libraries. There is currently no consensus regarding whether “zero-knowledge” naive libraries or libraries with pre-existing knowledge can offer a more effective path to discovery of molecular interactions. In this manuscript, we evaluated the feasibility of discovery of macrocyclic and bicyclic peptides from “nonzero-knowledge” libraries. We approach this problem by late-stage chemical reshaping of a preselected phage-displayed landscape of 20AA binders to NS3aH1 protease. The reshaping is performed using a novel multifunctional C₂-symmetric linchpin, 3,5-bis(bromomethyl)benzaldehyde (termed KYL), that combines two electrophiles that react with thiols and an aldehyde group that reacts with N-terminal amine. KYL diversified phage-displayed peptides into bicyclic architectures and delineated 2 distinct sequence populations: (i) peptides with the HXDMT motif that retained binding upon bicyclization and (ii) peptides without the HXDMT motif that lost binding once chemically modified. The same HXDMT family can be found in traditional selections starting from the naive KYL-modified library. Our report provides a case study for discovering advanced, chemically upgraded macrocycles and bicycles from libraries with pre-existing knowledge. The results imply that other selection campaigns completed in 20AA space, potentially, can serve for late-stage reshaping and as a starting point for the discovery of advanced peptide-derived ligands.","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":"86 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142858123","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}

{"title":"Highly Rigid, Yet Conformationally Adaptable, Bisporphyrin sp2-Cage Receptors Afford Outstanding Binding Affinities, Chelate Cooperativities, and Substrate Selectivities","authors":"A. Priscila Gia, Alberto de Juan, Daniel Aranda, Fernando G. Guijarro, Juan Aragó, Enrique Ortí, Miguel García-Iglesias, David González-Rodríguez","doi":"10.1021/jacs.4c13756","DOIUrl":"https://doi.org/10.1021/jacs.4c13756","url":null,"abstract":"If we aim to develop efficient synthetic models of protein receptors and enzymes, we must understand the relationships of intra- and intermolecular interactions between hosts and guests and how they mutually influence their conformational energy landscape so as to adapt to each other to maximize binding energies and enhance substrate selectivities. Here, we introduce a novel design of cofacial (Zn^II)bisporphyrin cages based on dynamic imine bonding, which is synthetically simple, but at the same time highly robust and versatile, affording receptors composed of only <i>sp</i>²-hybridized C and N atoms. The high structural rigidity of these cages renders them ideal hosts for ditopic molecules that can fit into the cavity and bind to both metal centers, leading to association constants as high as 10⁹ M^–1 in chloroform. These strong binding affinities are a consequence of the remarkable chelate cooperativities attained, with effective molarity (<i>EM</i>) values reaching record values over 10³ M. However, we discovered that the cages can still adapt their structure to a more <i>compact</i> version, able to host slightly smaller guests. Such a conformational transition has an energy cost, which can be very different depending on the direction of the imine linkages in the cage skeleton and which results in <i>EM</i> values 2–3 orders of magnitude lower. This interplay between cooperativity and conformational adaptability leads to strong and unusual selectivities. Not only these metalloporphyrin receptors can choose to bind preferably to a particular guest, as a function of its size, but also the guest can select which host to bind, as a function now of the host’s conformational rigidity. Such highly cooperative and selective associations are lost, however, in related flexible receptors where the imine bonds are reduced.","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":"10 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142858124","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}

{"title":"Oxygen Dimerization-Driven Cation Migration Induces Voltage Hysteresis in Disordered Rocksalt Cathodes","authors":"Byunghoon Kim, Peichen Zhong, Yunyeong Choi, Shashwat Anand, Han-Ming Hau, Bowen Deng, Gerbrand Ceder","doi":"10.1021/jacs.4c09070","DOIUrl":"https://doi.org/10.1021/jacs.4c09070","url":null,"abstract":"Despite the potential to increase the energy limit of Li-rich cathodes by using oxygen redox, its practicality has been limited by the accompanying structural changes and voltage hysteresis. While voltage hysteresis is commonly associated with transition metal (TM) migration and oxygen dimerization, the specific contribution of each is unclear. We provide a mechanistic insight into how each of these changes induces hysteresis in a representative Li-rich disordered rocksalt cathode, Li_1.2Mn_0.4Ti_0.4O₂. We reveal that the formation and cleavage of oxygen dimers can occur exceptionally rapidly during the electrochemical process, suggesting that the dimerization process is not directly the cause of voltage hysteresis, contrary to prevailing arguments. Instead, oxygen dimers are found to indirectly exacerbate hysteresis by instigating TM migration, which leads to the evolution of dimer-rich and TM-rich regions within the structure. We demonstrate that TM migration is relatively slower than dimerization and as such contributes to hysteresis by dissipating internal energy during the relaxation of charged electrodes and by inducing cation rearrangement with each cycle.","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":"75 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142858116","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}

{"title":"Controllable Active Intermediate in CO2 Hydrogenation Enabling Highly Selective N,N-Dimethylformamide Synthesis via N-Formylation","authors":"Jieyun Zhang, Guanna Li, Jin Xie, Yang Hai, Weiming Wan, Haotian Sun, Bin Wang, Xiaojing Wu, Jiannian Cheng, Changxin He, Wei Hu, Ying Zhang, Zelong Li, Can Li","doi":"10.1021/jacs.4c12503","DOIUrl":"https://doi.org/10.1021/jacs.4c12503","url":null,"abstract":"<i>N</i>,<i>N</i>-Dimethylformamide (DMF) is a widely used solvent, and its green and low-carbon synthesis methods are in high demand. Herein, we report a new approach for DMF synthesis using a continuous flow reaction system with a fixed-bed reactor and a ZnO-TiO₂ solid solution catalyst. This catalyst effectively utilizes CO₂, H₂, and dimethylamine (DMA) as feedstocks, demonstrating performance with 99% DMF selectivity and single-pass DMA conversion approaching thermodynamic equilibrium. Moreover, the catalyst demonstrates good stability, with no signs of deactivation over 1000 h of continuous operation. The key to superior activity lies in the synergetic effect of the Zn and Ti sites, which facilitates the formation of active formate species. These species act as crucial intermediates, reacting with DMA to produce DMF. Importantly, the slow hydrogenation kinetics of the formate species prevent the formation of CH₂O* species, thereby suppressing the formation of the undesired byproduct, trimethylamine. This work underscores the potential of kinetically controlling active intermediates in CO₂ hydrogenation to prepare high-value-added chemicals by coupling them to platform molecules. It presents a promising strategy for the efficient utilization of CO₂ resources and offers a valuable solution for large-scale DMF synthesis.","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":"334 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142858122","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}

{"title":"Stereo-Differentiating Asymmetric Rh(I)-Catalyzed Pauson–Khand Reaction: A DFT-Informed Approach to Thapsigargin Stereoisomers","authors":"Fatemeh Haghighi, Luke T. Jesikiewicz, Corrinne E. Stahl, Jordan Nafie, Amanda Ortega-Vega, Peng Liu, Kay M. Brummond","doi":"10.1021/jacs.4c11661","DOIUrl":"https://doi.org/10.1021/jacs.4c11661","url":null,"abstract":"We report a stereo-differentiating dynamic kinetic asymmetric Rh(I)-catalyzed Pauson–Khand reaction, which provides access to an array of thapsigargin stereoisomers. Using catalyst-control, a consistent stereochemical outcome is achieved at C2─for both matched and mismatched cases─regardless of the allene-yne C8 stereochemistry. The stereochemical configuration for all stereoisomers was assigned by comparing experimental vibrational circular dichroism (VCD) and ¹³C NMR to DFT-computed spectra. DFT calculations of the transition-state structures corroborate experimentally observed stereoselectivity and identify key stabilizing and destabilizing interactions between the chiral ligand and allene-yne PKR substrates. The robust nature of our catalyst-ligand system places the total synthesis of thapsigargin and its stereoisomeric analogues within reach.","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":"55 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142858121","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}

{"title":"Doublet Spin State Mediated Photoluminescence Upconversion in Organic Radical Donor-Triplet Acceptor Dyads","authors":"Joseph M. O’Shea, Young Ju Yun, Abdelqader M. Jamhawi, Francesca Peccati, Gonzalo Jiménez-Osés, Anoklase Jean-Luc Ayitou","doi":"10.1021/jacs.4c14303","DOIUrl":"https://doi.org/10.1021/jacs.4c14303","url":null,"abstract":"Donor–acceptor dyads are promising materials for improving triplet-sensitized photon upconversion due to faster intramolecular energy transfer (ET), which unfortunately competes with charge transfer (CT) dynamics. To circumvent the issue associated with CT, we propose a novel purely organic donor–acceptor dyad, where the CT character is confined within the donor moiety. In this work, we report the synthesis and characterization of a stable organic radical donor-triplet acceptor dyad (<b>TTM–Cz–Per</b>) consisting of the acceptor perylene (<b>Per</b>) linked to the donor (4-<i>N</i>-carbazolyl-2,6-dichlorophenyl)-bis(2,4,6-trichlorophenyl)methyl radical (<b>TTM–Cz</b>). Upon red-excitation of <b>TTM–Cz–Per</b>, the doublet emission of the donor (<b>TTM–Cz</b>) is significantly quenched, and a recorded delayed emission centered at ca. 490 nm was attributed to the fluorescence emission from the <b>Per</b> acceptor. Time-resolved transient absorption spectroscopy suggests doublet-to-triplet energy transfer (DTET) dynamics from the donor to the acceptor as the time constant τ for the donor transient species decreases from 21.47 ns for the <b>TTM–Cz</b> sensitizer to 8.73 ns for <b>TTM–Cz–Per</b> dyad. This process is accompanied by the appearance of a long-lived component with τ = 97.06 ns, which we ascribe to the triplet transient of the acceptor <b>Per</b>. Furthermore, computational results indicate that the DTET is intramolecular as computed spin densities of the quartet state show unpaired electrons of ρ ≈ 1 on the <b>TTM-Cz</b> donor and of ρ ≈ 2 on the acceptor <b>Per</b>. The present study highlights the possibility to employ doublet chromophoric systems for light-harvesting and energy upconversion, which can be further tailored for several optoelectronic applications.","PeriodicalId":49,"journal":{"name":"Journal of the American Chemical Society","volume":"40 1","pages":""},"PeriodicalIF":15.0,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142849527","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}