Pub Date : 2025-05-01Epub Date: 2022-10-26DOI: 10.1177/00302228221134205
Tanveer Ahmad Khan, Abdul Mohsin, Sumiya Din, Shaista Qayum, Irfanullah Farooqi
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.
{"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}
Pub Date : 2025-04-17DOI: 10.1021/acs.accounts.4c00845
Weiqing Xu, Yu Wu, Wenling Gu, Chengzhou Zhu
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.
{"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}
Pub Date : 2025-04-15DOI: 10.1021/acs.accounts.5c00097
Jishnudas Chakkamalayath, Akshaya Chemmangat, Jeffrey T. DuBose, Prashant V. Kamat
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.
{"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}
Pub Date : 2025-04-11DOI: 10.1021/acs.accounts.5c00086
Jianwei Yang, Bo Wang, Xiao Feng
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.
{"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}
Pub Date : 2025-04-11DOI: 10.1021/acs.accounts.5c00116
Gouranga H. Debnath, Prasun Mukherjee, David H. Waldeck
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.
{"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 (Ln<sup>3+</sup>, 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 Ln<sup>3+</sup> 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 Ln<sup>3+</sup> 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 Ln<sup>3+</sup> 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}
Pub Date : 2025-04-07DOI: 10.1021/acs.accounts.4c00773
Haowen Zhou, Taras Khvorost, Anastassia N Alexandrova, Justin R Caram
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.
{"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}
Pub Date : 2025-04-07DOI: 10.1021/acs.accounts.4c0077310.1021/acs.accounts.4c00773
Haowen Zhou, Taras Khvorost, Anastassia N. Alexandrova* and Justin R. Caram*,
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.
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.
{"title":"Vibronic Engineering for Quantum Functional Groups","authors":"Haowen Zhou, Taras Khvorost, Anastassia N. Alexandrova* and Justin R. Caram*, ","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}
Pub Date : 2025-04-04DOI: 10.1021/acs.accounts.4c00850
Wan Li, Ke Xu
<p><p>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<i>d</i>M) rises to the challenge. Rather than following each fluorescent molecule longitudinally as it randomly visits potentially heterogeneous environments, SM<i>d</i>M flips the question to ask, for every location (e.g., a 100 × 100 nm<sup>2</sup> 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<i>d</i>M thus successfully achieves super-resolution <i>D</i> mapping for fluorescently labeled molecules of contrasting sizes and properties in diverse cellular and <i>in vitro</i> systems.For intracellular protein diffusion, SM<i>d</i>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<i>d</i>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<i>d</i>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<i>d</i>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<i>d</i>M further affords a valuable means to quantify <i>D</i> with exceptional
{"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":"<p><p>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<i>d</i>M) rises to the challenge. Rather than following each fluorescent molecule longitudinally as it randomly visits potentially heterogeneous environments, SM<i>d</i>M flips the question to ask, for every location (e.g., a 100 × 100 nm<sup>2</sup> 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<i>d</i>M thus successfully achieves super-resolution <i>D</i> mapping for fluorescently labeled molecules of contrasting sizes and properties in diverse cellular and <i>in vitro</i> systems.For intracellular protein diffusion, SM<i>d</i>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<i>d</i>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<i>d</i>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<i>d</i>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<i>d</i>M further affords a valuable means to quantify <i>D</i> 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}
Pub Date : 2025-04-04DOI: 10.1021/acs.accounts.4c0085010.1021/acs.accounts.4c00850
Wan Li, and , Ke Xu*,
<p >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.</p><p >Single-molecule displacement/diffusivity mapping (SM<i>d</i>M) rises to the challenge. Rather than following each fluorescent molecule longitudinally as it randomly visits potentially heterogeneous environments, SM<i>d</i>M flips the question to ask, for every location (e.g., a 100 × 100 nm<sup>2</sup> 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<i>d</i>M thus successfully achieves super-resolution <i>D</i> mapping for fluorescently labeled molecules of contrasting sizes and properties in diverse cellular and <i>in vitro</i> systems.</p><p >For intracellular protein diffusion, SM<i>d</i>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<i>d</i>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<i>d</i>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<i>d</i>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<i>d</i>M further affords a valuable means to quantify <i>D</i> with excep
{"title":"Super-Resolution Mapping and Quantification of Molecular Diffusion via Single-Molecule Displacement/Diffusivity Mapping (SMdM)","authors":"Wan Li, and , Ke Xu*, ","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":"<p >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.</p><p >Single-molecule displacement/diffusivity mapping (SM<i>d</i>M) rises to the challenge. Rather than following each fluorescent molecule longitudinally as it randomly visits potentially heterogeneous environments, SM<i>d</i>M flips the question to ask, for every location (e.g., a 100 × 100 nm<sup>2</sup> 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<i>d</i>M thus successfully achieves super-resolution <i>D</i> mapping for fluorescently labeled molecules of contrasting sizes and properties in diverse cellular and <i>in vitro</i> systems.</p><p >For intracellular protein diffusion, SM<i>d</i>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<i>d</i>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<i>d</i>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<i>d</i>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<i>d</i>M further affords a valuable means to quantify <i>D</i> 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}
Pub Date : 2025-04-04DOI: 10.1021/acs.accounts.5c0011910.1021/acs.accounts.5c00119
Sharon Hammes-Schiffer*,
<p >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.</p><p >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.</p><p >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.</p><p >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
质子耦合电子转移（PCET）对多种化学和生物过程至关重要。了解 PCET 反应的机理对于控制和调整这些过程非常重要。动能同位素效应（KIE）被定义为氢和氘转移的速率常数之比，它被用来在实验中探究 PCET 的机理，但往往难以解释。本文介绍了一种解释协同 PCET 反应 KIE 的理论框架。第一步是根据振动和电子-质子非绝热性对反应进行分类，它们反映了电子、质子和环境的相对时间尺度。第二步是根据这一分类选择合适的速率常数表达式。振动绝热 PCET 反应发生在电子和振动基态上，可以在过渡态理论框架内进行描述。核电子轨道（NEO）方法将指定质子的量子力学处理在与电子相同的水平上，可用于生成氢和氘的电子-质子振动自由能面，并计算相应的自由能垒。振子非绝热 PCET 反应涉及激发的电子-质子振子态，可以用对应于反应物和生成物对振子态之间非绝热跃迁的金科玉律形式来描述。此类反应的 KIE 值从一到五百不等，甚至略低于一。这些 KIE 可以用多个相互竞争的反应途径来解释，这些途径与不同对振子态之间的电子和质子隧穿相对应。隧穿概率由振子耦合决定，振子耦合可以用一般的表达式计算，但通常与反应物和生成物质子振动波函数之间的重叠成正比。在这种情况下，KIE 受振动耦合、质子供体-受体平衡距离和运动以及激发振动态贡献的影响。在大豆脂氧合酶中，野生型酶的 KIE 值为 ∼80 ∼700，而双突变体的 KIE 值为 ∼700 ∼80，这是由于质子供体-受体的平衡距离较大，且取向不理想，导致振动波函数之间的重叠较小，因此氢和氘的隧穿概率差异较大。苯并咪唑-苯酚分子的 KIE 值从统一到适中不等，这是因为具有不同振动波函数重叠的不同振动态对占主导地位。在乙腈中，质子从三乙基铵酸向金表面放电时观察到的随电势变化的 KIE 可解释为氢和氘的不同振动态对，反应通道表现出对应用电势的不同依赖性。这些示例表明，KIE 可以有很大的差异，这取决于哪些振子态对占主导地位及其相应的振子耦合。这项工作对解释 PCET 反应的实验测量 KIE 具有广泛的意义。
{"title":"Explaining Kinetic Isotope Effects in Proton-Coupled Electron Transfer Reactions","authors":"Sharon Hammes-Schiffer*, ","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":"<p >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.</p><p >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.</p><p >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.</p><p >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}
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