Accounts of Chemical Research最新文献

{"title":"Last Honors and Life Experiences of Bereaved Families in the Context of COVID-19 in Kashmir: A Qualitative Inquiry About Exclusion, Family Trauma, and Other Issues.","authors":"Tanveer Ahmad Khan, Abdul Mohsin, Sumiya Din, Shaista Qayum, Irfanullah Farooqi","doi":"10.1177/00302228221134205","DOIUrl":"10.1177/00302228221134205","url":null,"abstract":"<p><p>This study examined the changing character of the last honours of those who died of COVID-19 in Kashmir and the life experiences of the families of the deceased. A semi-structured interview schedule was used to collect information from 21 participants. Using qualitative data analysis approaches, five key themes were identified vis-à-vis the impact of COVID-19 on burial rituals and customs; effects on bereaved families, shades of grief, bereavement care, community response, and coping with loss. Based on examining the pandemic-induced changes related to customs and rituals around death, the study found that the bereaved family members were in danger of marginalization, economic burdens, psychological traumas, and overall reduced quality of life. This study would be a credible addition to the existing literature on death practices as there is a shortage of research on funeral rituals during the post-pandemic period in Kashmir.</p>","PeriodicalId":1,"journal":{"name":"Accounts of Chemical Research","volume":" ","pages":"361-382"},"PeriodicalIF":16.4,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9606636/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42358876","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Atomically Dispersed Metal Interfaces for Analytical Chemistry","authors":"Weiqing Xu, Yu Wu, Wenling Gu, Chengzhou Zhu","doi":"10.1021/acs.accounts.4c00845","DOIUrl":"https://doi.org/10.1021/acs.accounts.4c00845","url":null,"abstract":"Engineering sensing interfaces with functional nanomaterials have aroused great interest in constructing novel analytical platforms. The good catalytic abilities and physicochemical properties allow functional nanomaterials to perform catalytic signal transductions and synergistically amplify biorecognition events for efficient target analysis. However, further boosting their catalytic performances poses grand challenges in achieving more sensitive and selective sample assays. Besides, nanomaterials with abundant atomic compositions and complex structural characteristics bring about more difficulties in understanding the underlying mechanism of signal amplification. Atomically dispersed metal catalysts (ADMCs), as an emerging class of heterogeneous catalysts, feature support-stabilized isolated metal catalytic sites, showing maximum metal utilization and a strong metal–support interfacial interaction. These unique structural characteristics are akin to those of homogeneous catalysts, which have well-defined coordination structures between metal sites with synthetic or biological ligands. By integrating the advantages of heterogeneous and homogeneous catalysts, ADMCs present superior catalytic activity and specificity relative to the nanoparticles formed by the nonuniform aggregation of active sites. ADMC-enabled sensing platforms have been demonstrated to realize advanced applications in various fields. Notably, the easily tunable coordination structures of ADMCs bring more opportunities to improve their catalytic performance, further moving toward efficient signal transduction ability. Besides, by leveraging their inherent physicochemical properties and various detection strategies, ADMC-enabled sensing interfaces not only achieve enhanced signal transductions but also show diversified output models. Such superior functions allow ADMC-enabled sensing platforms to access the goal of high-performance detection of trace targets and making significant progress in analytical chemistry.","PeriodicalId":1,"journal":{"name":"Accounts of Chemical Research","volume":"6 1","pages":""},"PeriodicalIF":18.3,"publicationDate":"2025-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143846547","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":"Photon Management Through Energy Transfer in Halide Perovskite Nanocrystal–Dye Hybrids: Singlet vs Triplet Tuning","authors":"Jishnudas Chakkamalayath, Akshaya Chemmangat, Jeffrey T. DuBose, Prashant V. Kamat","doi":"10.1021/acs.accounts.5c00097","DOIUrl":"https://doi.org/10.1021/acs.accounts.5c00097","url":null,"abstract":"Photoinduced energy and electron transfer processes offer a convenient way to convert light energy into electrical or chemical energy. These processes remain the basis of operation of thin film solar cells, light emitting and optoelectronic devices, and solar fuel generation. In many of these applications, semiconductor nanocrystals that absorb in the visible and near-infrared region are the building blocks that harvest photons and initiate energy or electron transfer to surface-bound chromophores. Such multifunctional aspects make it challenging to steer the energy transfer pathway selectively. Proper selection of the semiconductor nanocrystal donor requires consideration of the nanocrystal bandgap, along with the alignment of valence and conduction band energies relative to that of the acceptor, in order to achieve desired output of energy or electron transfer.","PeriodicalId":1,"journal":{"name":"Accounts of Chemical Research","volume":"3 1","pages":""},"PeriodicalIF":18.3,"publicationDate":"2025-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143831989","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":"Mass Transport Based on Covalent Organic Frameworks","authors":"Jianwei Yang, Bo Wang, Xiao Feng","doi":"10.1021/acs.accounts.5c00086","DOIUrl":"https://doi.org/10.1021/acs.accounts.5c00086","url":null,"abstract":"Mass transport is fundamental to biological systems and industrial processes, governing chemical reactions, substance exchange, and energy conversion across various material scales. In biological systems, ion transport, such as proton migration through voltage-gated proton channels, regulates cellular potential, signaling, and metabolic balance. In industrial processes, transporting molecules through solid, liquid, or gas phases dictates reactant contact and diffusion rates, directly impacting reaction efficiency and conversion. Optimizing these processes necessitates the design of efficient interfaces or channels to enhance mass transport.","PeriodicalId":1,"journal":{"name":"Accounts of Chemical Research","volume":"60 1","pages":""},"PeriodicalIF":18.3,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143822424","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":"Identifying Lanthanide Energy Levels in Semiconductor Nanoparticles Enables Tailored Multicolor Emission through Rational Dopant Combinations","authors":"Gouranga H. Debnath, Prasun Mukherjee, David H. Waldeck","doi":"10.1021/acs.accounts.5c00116","DOIUrl":"https://doi.org/10.1021/acs.accounts.5c00116","url":null,"abstract":"The unique photon emission signatures of trivalent lanthanide cations (Ln³⁺, where Ln = Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Yb) enables multicolor emission from semiconductor nanoparticles (NPs) either through doping multiple Ln³⁺ ions of distinct identities or in combination with other elements for the creation of next-generation light emitting diodes (LEDs), lasers, sensors, imaging probes, and other optoelectronic devices. Although advancements have been made in synthetic strategies to dope Ln³⁺ in semiconductor NPs, the dopant(s) selection criteria have hinged largely on trial-and-error. This combinatorial approach is often guided by treating NP–dopant(s) energy transfer dynamics through the lens of spectral overlap. Over the past decade, however, we have demonstrated that the spectral outcomes correlate better with the placement of Ln³⁺ energy levels with respect to the band edges of the semiconductor, and oxide, host.","PeriodicalId":1,"journal":{"name":"Accounts of Chemical Research","volume":"5 1","pages":""},"PeriodicalIF":18.3,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143822512","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":"Vibronic Engineering for Quantum Functional Groups.","authors":"Haowen Zhou, Taras Khvorost, Anastassia N Alexandrova, Justin R Caram","doi":"10.1021/acs.accounts.4c00773","DOIUrl":"https://doi.org/10.1021/acs.accounts.4c00773","url":null,"abstract":"<p><p>ConspectusChemists have a firm understanding of the concept of a functional group: a small molecular moiety that confers properties (reactivity, solubility, and chemical recognition) onto a larger scaffold. Analogously, a quantum functional group (QFG) would act as an isolated \"quantum handle\" that could attach onto an extended molecule and enable quantum state preparation and measurement (SPAM). However, the complexity associated with molecular chemistry is often at odds with the requirements of nonthermal state preparation. The rest of the molecule acts as a local bath that leads to dephasing and loss of quantum information upon excitation and relaxation. Yet, there exists an enormous chemical space of potential chemical bonding motifs to design isolated QFGs. The goal of this Account is to explore the underlying chemical design principles for the optimization of QFG performance.For typical state preparation, an applied field is used to put the qubit into a specific known state (via optical cycling and laser cooling), where it can be manipulated or entangled with other species. That same field (or another) can be used to read out or report on the qubit state at the end of the operation. For example, in trapped ions/neutral atoms, state preparation is accomplished by pumping a specific transition using a narrowband laser. From there, further operations can be performed on the qubit via selective RF or laser excitation, and the state can be read out via fluorescence. However, extending this paradigm to molecular systems is highly challenging: molecules have many more degrees of freedom that can couple to the absorbed or emitted field. Overcoming this requires greatly limiting the number of these \"off-diagonal\" decay pathways through the judicious selection of the QFG and vibronic engineering of the molecular substrate.Our work has demonstrated that alkaline-earth (I) alkoxides (MOR) may meet the necessary requirements for efficient SPAM. In particular, we capitalize on the -OM (M = Ca, Sr) motif, which acts as a quantum handle that has been attached to a variety of aliphatic and aromatic hydrocarbons. The precise breakdown of the optical cycling property depends on familiar chemical concepts, including conjugation, conformer formation, electron-withdrawing abilities, and symmetry. In this Account, we review the recent efforts in the field to construct QFGs and codesign molecular scaffolds that can host them without destruction of their desired quantum properties. QFGs are explored as attachments to photoswitching scaffolds and mounted in pairs to larger hosts. A variety of physical phenomena relevant to the ability of these QFGs to function as qubits, from Fermi resonances to super radiance, have been explored. We thus began deriving the first set of rules for vibronic engineering toward the QFG functionality. Prospects toward increasing the number densities of these QFGs through molecular and material design are also presented.</p>","PeriodicalId":1,"journal":{"name":"Accounts of Chemical Research","volume":" ","pages":""},"PeriodicalIF":16.4,"publicationDate":"2025-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143794006","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":"Vibronic Engineering for Quantum Functional Groups","authors":"Haowen Zhou,&nbsp;Taras Khvorost,&nbsp;Anastassia N. Alexandrova* and Justin R. Caram*,&nbsp;","doi":"10.1021/acs.accounts.4c0077310.1021/acs.accounts.4c00773","DOIUrl":"https://doi.org/10.1021/acs.accounts.4c00773https://doi.org/10.1021/acs.accounts.4c00773","url":null,"abstract":"<p >Chemists have a firm understanding of the concept of a functional group: a small molecular moiety that confers properties (reactivity, solubility, and chemical recognition) onto a larger scaffold. Analogously, a quantum functional group (QFG) would act as an isolated “quantum handle” that could attach onto an extended molecule and enable quantum state preparation and measurement (SPAM). However, the complexity associated with molecular chemistry is often at odds with the requirements of nonthermal state preparation. The rest of the molecule acts as a local bath that leads to dephasing and loss of quantum information upon excitation and relaxation. Yet, there exists an enormous chemical space of potential chemical bonding motifs to design isolated QFGs. The goal of this Account is to explore the underlying chemical design principles for the optimization of QFG performance.</p><p >For typical state preparation, an applied field is used to put the qubit into a specific known state (via optical cycling and laser cooling), where it can be manipulated or entangled with other species. That same field (or another) can be used to read out or report on the qubit state at the end of the operation. For example, in trapped ions/neutral atoms, state preparation is accomplished by pumping a specific transition using a narrowband laser. From there, further operations can be performed on the qubit via selective RF or laser excitation, and the state can be read out via fluorescence. However, extending this paradigm to molecular systems is highly challenging: molecules have many more degrees of freedom that can couple to the absorbed or emitted field. Overcoming this requires greatly limiting the number of these “off-diagonal” decay pathways through the judicious selection of the QFG and vibronic engineering of the molecular substrate.</p><p >Our work has demonstrated that alkaline-earth (I) alkoxides (MOR) may meet the necessary requirements for efficient SPAM. In particular, we capitalize on the −OM (M = Ca, Sr) motif, which acts as a quantum handle that has been attached to a variety of aliphatic and aromatic hydrocarbons. The precise breakdown of the optical cycling property depends on familiar chemical concepts, including conjugation, conformer formation, electron-withdrawing abilities, and symmetry. In this Account, we review the recent efforts in the field to construct QFGs and codesign molecular scaffolds that can host them without destruction of their desired quantum properties. QFGs are explored as attachments to photoswitching scaffolds and mounted in pairs to larger hosts. A variety of physical phenomena relevant to the ability of these QFGs to function as qubits, from Fermi resonances to super radiance, have been explored. We thus began deriving the first set of rules for vibronic engineering toward the QFG functionality. Prospects toward increasing the number densities of these QFGs through molecular and material design are also presented.</p>","PeriodicalId":1,"journal":{"name":"Accounts of Chemical Research","volume":"58 8","pages":"1181–1191 1181–1191"},"PeriodicalIF":16.4,"publicationDate":"2025-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143827978","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":"Super-Resolution Mapping and Quantification of Molecular Diffusion via Single-Molecule Displacement/Diffusivity Mapping (SM<i>d</i>M).","authors":"Wan Li, Ke Xu","doi":"10.1021/acs.accounts.4c00850","DOIUrl":"10.1021/acs.accounts.4c00850","url":null,"abstract":"&lt;p&gt;&lt;p&gt;ConspectusDiffusion underlies vital physicochemical and biological processes and provides a valuable window into molecular states and interactions. However, it remains a challenge to map molecular diffusion at subcellular and submicrometer scales. Whereas single-particle tracking of fluorescent molecules provides a path to quantify motion at the nanoscale, its typical pursuit of long trajectories limits wide-field mapping to the slow diffusion of bound molecules.Single-molecule displacement/diffusivity mapping (SM&lt;i&gt;d&lt;/i&gt;M) rises to the challenge. Rather than following each fluorescent molecule longitudinally as it randomly visits potentially heterogeneous environments, SM&lt;i&gt;d&lt;/i&gt;M flips the question to ask, for every location (e.g., a 100 × 100 nm&lt;sup&gt;2&lt;/sup&gt; spatial bin) in a wide field, how different single molecules of identical nature move locally. This location-centered strategy is naturally effective for spatial mapping of diffusivity. Moreover, by focusing on local motion, each molecule only needs to be detected for its transient displacement within a fixed short time window to achieve local statistics. This task is fulfilled for fast-diffusing molecules using a tandem excitation scheme in which a pair of closely timed stroboscopic excitation pulses are applied across two tandem frames, so that wide-field single-molecule images are recorded at a pulse-defined ≲1 ms separation unlimited by the camera frame rate. With fitting models robust against mismatched molecules and diffusion anisotropy, SM&lt;i&gt;d&lt;/i&gt;M thus successfully achieves super-resolution &lt;i&gt;D&lt;/i&gt; mapping for fluorescently labeled molecules of contrasting sizes and properties in diverse cellular and &lt;i&gt;in vitro&lt;/i&gt; systems.For intracellular protein diffusion, SM&lt;i&gt;d&lt;/i&gt;M uncovers nanoscale diffusion heterogeneities in the mammalian cytoplasm and nucleus and further elucidates their origins from the macromolecular crowding effects of cytoskeletal and chromatin ultrastructures, respectively, through correlated single-molecule localization microscopy (SMLM). Across diverse compartments of the mammalian cell, including the cytoplasm, the nucleus, the endoplasmic reticulum (ER) lumen, and the mitochondrial matrix, SM&lt;i&gt;d&lt;/i&gt;M further unveils a striking charge effect, in which the diffusion of positively charged proteins is biasedly impeded. For cellular membranes, the integration of SM&lt;i&gt;d&lt;/i&gt;M with fluorogenic probes enables diffusivity fine-mapping, which, in combination with spectrally resolved SMLM (SR-SMLM), elucidates nanoscale diffusional heterogeneities of different origins. For biomolecular condensates, another synergy of SM&lt;i&gt;d&lt;/i&gt;M and SR-SMLM uncovers the gradual formation of diffusion-suppressed, hydrophobic amyloid nanoaggregates at the surface of FUS (fused in sarcoma) protein condensates during aging. Beyond spatial mapping, the mass accumulation of single-molecule displacements in SM&lt;i&gt;d&lt;/i&gt;M further affords a valuable means to quantify &lt;i&gt;D&lt;/i&gt; with exceptional ","PeriodicalId":1,"journal":{"name":"Accounts of Chemical Research","volume":" ","pages":""},"PeriodicalIF":16.4,"publicationDate":"2025-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143778539","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":"Super-Resolution Mapping and Quantification of Molecular Diffusion via Single-Molecule Displacement/Diffusivity Mapping (SMdM)","authors":"Wan Li,&nbsp; and ,&nbsp;Ke Xu*,&nbsp;","doi":"10.1021/acs.accounts.4c0085010.1021/acs.accounts.4c00850","DOIUrl":"https://doi.org/10.1021/acs.accounts.4c00850https://doi.org/10.1021/acs.accounts.4c00850","url":null,"abstract":"&lt;p &gt;Diffusion underlies vital physicochemical and biological processes and provides a valuable window into molecular states and interactions. However, it remains a challenge to map molecular diffusion at subcellular and submicrometer scales. Whereas single-particle tracking of fluorescent molecules provides a path to quantify motion at the nanoscale, its typical pursuit of long trajectories limits wide-field mapping to the slow diffusion of bound molecules.&lt;/p&gt;&lt;p &gt;Single-molecule displacement/diffusivity mapping (SM&lt;i&gt;d&lt;/i&gt;M) rises to the challenge. Rather than following each fluorescent molecule longitudinally as it randomly visits potentially heterogeneous environments, SM&lt;i&gt;d&lt;/i&gt;M flips the question to ask, for every location (e.g., a 100 × 100 nm&lt;sup&gt;2&lt;/sup&gt; spatial bin) in a wide field, how different single molecules of identical nature move locally. This location-centered strategy is naturally effective for spatial mapping of diffusivity. Moreover, by focusing on local motion, each molecule only needs to be detected for its transient displacement within a fixed short time window to achieve local statistics. This task is fulfilled for fast-diffusing molecules using a tandem excitation scheme in which a pair of closely timed stroboscopic excitation pulses are applied across two tandem frames, so that wide-field single-molecule images are recorded at a pulse-defined ≲1 ms separation unlimited by the camera frame rate. With fitting models robust against mismatched molecules and diffusion anisotropy, SM&lt;i&gt;d&lt;/i&gt;M thus successfully achieves super-resolution &lt;i&gt;D&lt;/i&gt; mapping for fluorescently labeled molecules of contrasting sizes and properties in diverse cellular and &lt;i&gt;in vitro&lt;/i&gt; systems.&lt;/p&gt;&lt;p &gt;For intracellular protein diffusion, SM&lt;i&gt;d&lt;/i&gt;M uncovers nanoscale diffusion heterogeneities in the mammalian cytoplasm and nucleus and further elucidates their origins from the macromolecular crowding effects of cytoskeletal and chromatin ultrastructures, respectively, through correlated single-molecule localization microscopy (SMLM). Across diverse compartments of the mammalian cell, including the cytoplasm, the nucleus, the endoplasmic reticulum (ER) lumen, and the mitochondrial matrix, SM&lt;i&gt;d&lt;/i&gt;M further unveils a striking charge effect, in which the diffusion of positively charged proteins is biasedly impeded. For cellular membranes, the integration of SM&lt;i&gt;d&lt;/i&gt;M with fluorogenic probes enables diffusivity fine-mapping, which, in combination with spectrally resolved SMLM (SR-SMLM), elucidates nanoscale diffusional heterogeneities of different origins. For biomolecular condensates, another synergy of SM&lt;i&gt;d&lt;/i&gt;M and SR-SMLM uncovers the gradual formation of diffusion-suppressed, hydrophobic amyloid nanoaggregates at the surface of FUS (fused in sarcoma) protein condensates during aging. Beyond spatial mapping, the mass accumulation of single-molecule displacements in SM&lt;i&gt;d&lt;/i&gt;M further affords a valuable means to quantify &lt;i&gt;D&lt;/i&gt; with excep","PeriodicalId":1,"journal":{"name":"Accounts of Chemical Research","volume":"58 8","pages":"1224–1235 1224–1235"},"PeriodicalIF":16.4,"publicationDate":"2025-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143827960","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":"Explaining Kinetic Isotope Effects in Proton-Coupled Electron Transfer Reactions","authors":"Sharon Hammes-Schiffer*,&nbsp;","doi":"10.1021/acs.accounts.5c0011910.1021/acs.accounts.5c00119","DOIUrl":"https://doi.org/10.1021/acs.accounts.5c00119https://doi.org/10.1021/acs.accounts.5c00119","url":null,"abstract":"&lt;p &gt;Proton-coupled electron transfer (PCET) is essential for a wide range of chemical and biological processes. Understanding the mechanism of PCET reactions is important for controlling and tuning these processes. The kinetic isotope effect (KIE), defined as the ratio of the rate constants for hydrogen and deuterium transfer, is used to probe PCET mechanisms experimentally but is often challenging to interpret. Herein, a theoretical framework is described for interpreting KIEs of concerted PCET reactions. The first step is to classify the reaction in terms of vibronic and electron–proton nonadiabaticities, which reflect the relative time scales of the electrons, protons, and environment. The second step is to select the appropriate rate constant expression based on this classification. The third step is to compute the input quantities with computational methods.&lt;/p&gt;&lt;p &gt;Vibronically adiabatic PCET reactions occur on the electronic and vibrational ground state and can be described within the transition state theory framework. The nuclear−electronic orbital (NEO) method, which treats specified protons quantum mechanically on the same level as the electrons, can be used to generate the electron–proton vibronic free energy surface for hydrogen and deuterium and to compute the corresponding free energy barriers. Such reactions typically exhibit moderate KIEs that arise from zero-point energy and shallow tunneling effects.&lt;/p&gt;&lt;p &gt;Vibronically nonadiabatic PCET reactions involve excited electron–proton vibronic states and can be described with a golden rule formalism corresponding to nonadiabatic transitions between pairs of reactant and product vibronic states. Such reactions can exhibit KIEs ranging from unity, or even slightly less than unity, to more than 500. These KIEs can be explained in terms of multiple, competing reaction pathways corresponding to electron and proton tunneling between different pairs of vibronic states. The tunneling probability is determined by the vibronic coupling, which can be computed using a general expression but often is proportional to the overlap between the reactant and product proton vibrational wave functions. In this regime, the KIE is influenced by the vibronic couplings, the proton donor–acceptor equilibrium distance and motion, and contributions from excited vibronic states.&lt;/p&gt;&lt;p &gt;Three illustrative examples of vibronically nonadiabatic PCET are discussed. The unusually large KIEs in soybean lipoxygenase of ∼80 for the wild-type enzyme and ∼700 for a double mutant are explained in terms of a large equilibrium proton donor–acceptor distance and nonoptimal orientation, leading to a small overlap between vibrational wave functions and therefore a large difference in hydrogen and deuterium tunneling probabilities. The KIEs for benzimidazole-phenol molecules ranging from unity to moderate are explained in terms of the dominance of different pairs of vibronic states with different vibrational wave function overlaps","PeriodicalId":1,"journal":{"name":"Accounts of Chemical Research","volume":"58 8","pages":"1335–1344 1335–1344"},"PeriodicalIF":16.4,"publicationDate":"2025-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143827907","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}