1
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Peacock H, Blum SA. Buildup and Consumption of Species in Emulsion Droplets during Aqueous Suzuki Coupling Correlate with Yield. J Org Chem 2024; 89:10684-10692. [PMID: 39016689 DOI: 10.1021/acs.joc.4c00918] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/18/2024]
Abstract
Fluorescence lifetime imaging microscopy (FLIM) provides spatiotemporal resolution of the changing composition of emulsion droplets during aqueous-surfactant Suzuki coupling. In contrast to previous investigations, the present experiments characterize the full course of a catalytic chemical reaction, addressing key questions about reaction species buildup and correlating these microscale behaviors with bench-scale product yields. At low concentrations of (active) catalyst, droplet environments are stable; however, at higher concentrations, emulsion droplet environments change markedly. These changes are consistent with the buildup and consumption of reaction species inside the droplets. A combination of FLIM and bright-field imaging pinpoints limitations in catalyst solubility as controlling rate and degree of buildup of species in droplets. These solubility limitations are also identified as the cause of a reaction induction period and an origin of the rate-and-reproducibility advantage obtained by adding THF cosolvent. The subsequent mechanistic model from these data led to a bench-scale reaction optimization, wherein premixing the catalyst components bypasses the catalyst induction period, resulting in a faster reaction. The understanding generated by FLIM thus provides an early example of how visualizing changes in droplet compositions on the microscale during ongoing aqueous-organic reactions can be leveraged for enhancing efficiencies in bench-scale reactions.
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Affiliation(s)
- Hannah Peacock
- Department of Chemistry, University of California, Irvine, Irvine, California 92697-2025, United States
| | - Suzanne A Blum
- Department of Chemistry, University of California, Irvine, Irvine, California 92697-2025, United States
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2
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Reis IF, Gehlen MH. Single-Molecule Catalysis in the Palladium Cross-Coupling Reaction Cycle. J Phys Chem Lett 2024; 15:2352-2358. [PMID: 38388364 DOI: 10.1021/acs.jpclett.3c03623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2024]
Abstract
Single-molecule (SM) methods are applied to study various types of catalytic processes in chemical and biochemical reactions. In this study, the Suzuki-Miyaura cross-coupling reaction forming a fluorescent product is investigated within the SM approximation. Stochastic analysis of emission intermittency in selected nanoscopic spots allows us to determine the single-molecule turnover frequency (SM-TOF) of the Pd catalyst in a specific probe reaction. We generate and analyze simulated intermittency time traces of a single catalyst surrounded by reactant molecules to assess the reliability of the method applied to real intermittency time trace data from hundreds of nanoscopic fluorescence spots. The results demonstrate that the proposed method can be used to evaluate the average SM-TOF of Pd in a cross-coupling reaction.
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Affiliation(s)
- Izadora F Reis
- Department of Physical Chemistry, Institute of Chemistry of São Carlos, University of São Paulo, São Carlos, São Paulo 13566-590, Brazil
| | - Marcelo H Gehlen
- Department of Physical Chemistry, Institute of Chemistry of São Carlos, University of São Paulo, São Carlos, São Paulo 13566-590, Brazil
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3
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Hanada EM, McShea PJ, Blum SA. Trimethylsilyl Chloride Aids in Solubilization of Oxidative Addition Intermediates from Zinc Metal. Angew Chem Int Ed Engl 2023; 62:e202307787. [PMID: 37672719 PMCID: PMC10591914 DOI: 10.1002/anie.202307787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Revised: 08/26/2023] [Accepted: 09/06/2023] [Indexed: 09/08/2023]
Abstract
Trimethylsilyl chloride (TMSCl) is commonly used to "activate" metal(0) powders toward oxidative addition of organohalides, but knowledge of its mechanism remains limited by the inability to characterize chemical intermediates under reaction conditions. Here, fluorescence lifetime imaging microscopy (FLIM) overcomes these prior limitations and shows that TMSCl aids in solubilization of the organozinc intermediate from zinc(0) metal after oxidative addition, a previously unknown mechanistic role. This mechanistic role is in contrast to previously known roles for TMSCl before the oxidative addition step. To achieve this understanding, FLIM, a tool traditionally used in biology, is developed to characterize intermediates during a chemical reaction-thus revealing mechanistic steps that are unobservable without fluorescence lifetime data. These findings impact organometallic reagent synthesis and catalysis by providing a previously uncharacterized mechanistic role for a widely used activating agent, an understanding of which is suitable for revising activation models and for developing strategies to activate currently unreactive metals.
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Affiliation(s)
- Erin M Hanada
- Chemistry Department, University of California, Irvine, Irvine, CA 92697-2025, USA
| | - Patrick J McShea
- Chemistry Department, University of California, Irvine, Irvine, CA 92697-2025, USA
| | - Suzanne A Blum
- Chemistry Department, University of California, Irvine, Irvine, CA 92697-2025, USA
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4
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Nguyen D, Yan G, Chen TY, Do LH. Variations in Intracellular Organometallic Reaction Frequency Captured by Single-Molecule Fluorescence Microscopy. Angew Chem Int Ed Engl 2023; 62:e202300467. [PMID: 37285476 PMCID: PMC10526727 DOI: 10.1002/anie.202300467] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Revised: 06/06/2023] [Accepted: 06/07/2023] [Indexed: 06/09/2023]
Abstract
Studies of organometallic reactions in living cells commonly rely on ensemble-averaged measurements, which can obscure the detection of reaction dynamics or location-specific behavior. This information is necessary to guide the design of bioorthogonal catalysts with improved biocompatibility, activity, and selectivity. By leveraging the high spatial and temporal resolution of single-molecule fluorescence microscopy, we have successfully captured single-molecule events promoted by Ru complexes inside live A549 human lung cells. By observing individual allylcarbamate cleavage reactions in real-time, our results revealed that they occur with greater frequency inside the mitochondria than in the non-mitochondria regions. The estimated turnover frequency of the Ru complexes was at least 3-fold higher in the former than the latter. These results suggest that organelle specificity is a critical factor to consider in intracellular catalyst design, such as in developing metallodrugs for therapeutic applications.
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Affiliation(s)
- Dat Nguyen
- Faculty of Chemical and Food Technology, Ho Chi Minh City University of Technology and Education, 1 Vo Van Ngan, Thu Duc City, Ho Chi Minh City, Vietnam
| | - Guangjie Yan
- Department of Chemistry, University of Houston, 4800 Calhoun Rd., TX 77004, Houston, USA
| | - Tai-Yen Chen
- Department of Chemistry, University of Houston, 4800 Calhoun Rd., TX 77004, Houston, USA
| | - Loi H Do
- Department of Chemistry, University of Houston, 4800 Calhoun Rd., TX 77004, Houston, USA
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5
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Peacock H, Blum SA. Surfactant Micellar and Vesicle Microenvironments and Structures under Synthetic Organic Conditions. J Am Chem Soc 2023; 145:7648-7658. [PMID: 36951303 PMCID: PMC10079647 DOI: 10.1021/jacs.3c01574] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/24/2023]
Abstract
Fluorescence lifetime imaging microscopy (FLIM) reveals vesicle sizes, structures, microenvironments, reagent partitioning, and system evolution with two chemical reactions for widely used surfactant-water systems under conditions relevant to organic synthesis, including during steps of Negishi cross-coupling reactions. In contrast to previous investigations, the present experiments characterize surfactant systems with representative organohalide substrates at high concentrations (0.5 M) that are reflective of the preparative-scale organic reactions performed and reported in water. In the presence of representative organic substrates, 2-iodoethylbenzene and 2-bromo-6-methoxypyridine, micelles swell into emulsion droplets that are up to 20 μm in diameter, which is 3-4 orders of magnitude larger than previously measured in the absence of an organic substrate (5-200 nm). The partitioning of reagents in these systems is imaged through FLIM─demonstrated here with nonpolar, amphiphilic, organic, basic, and oxidative-addition reactive compounds, a reactive zinc metal powder, and a palladium catalyst. FLIM characterizes the chemical species and/or provides microenvironment information inside micelles and vesicles. These data show that surfactants cause surfactant-dictated microenvironments inside smaller micelles (<200 nm) but that addition of a representative organic substrate produces internal microenvironments dictated primarily by the substrate rather than by the surfactant, concurrent with swelling. Addition of a palladium catalyst causes the internal environments to differ between vesicles─information that is not available through nor predicted from prior analytical techniques. Together, these data provide immediately actionable information for revising reaction models of surfactant-water systems that underpin the development of sustainable organic chemistry in water.
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Affiliation(s)
- Hannah Peacock
- Department of Chemistry, University of California, Irvine, Irvine, California 92697-2025, United States
| | - Suzanne A. Blum
- Department of Chemistry, University of California, Irvine, Irvine, California 92697-2025, United States
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6
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Optical and Thermal Investigations of Eutectic Metallomesogen Mixtures Based on Salicylaldiaminates Metal Complexes with a Large Nematic Stability Range. INORGANICS 2023. [DOI: 10.3390/inorganics11010032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The mesomorphic behavior and the miscibility properties of binary mixtures of a new series of Schiff base metallomesogen (MOM) are evaluated by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). Nuclear magnetic resonance (NMR), elemental analysis (CHNX), Fourier−transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) were used to certify the molecular structure of the compounds. The results revealed that the studied mixtures are completely miscible throughout the composition field and exhibit a nematic phase which covered the whole composition range. In the mixtures, the stability of the nematic phase varies continuously, and it is possible to highlight the presence of a eutectic composition with a wide mesogenic stability range.
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7
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Shinozaki Y, Popov S, Plenio H. Fluorescent organometallic dyads and triads: establishing spatial relationships. Chem Sci 2023; 14:350-361. [PMID: 36687348 PMCID: PMC9811503 DOI: 10.1039/d2sc04869h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Accepted: 12/04/2022] [Indexed: 12/12/2022] Open
Abstract
FRET pairs involving up to three different Bodipy dyes are utilized to provide information on the assembly/disassembly of organometallic complexes. Azolium salts tagged with chemically robust and photostable blue or green or red fluorescent Bodipy, respectively, were synthesized and the azolium salts used to prepare metal complexes [(NHC_blue)ML], [(NHC_green)ML] and [(NHC_red)ML] (ML = Pd(allyl)Cl, IrCl(cod), RhCl(cod), AuCl, Au(NTf2), CuBr). The blue and the green Bodipy and the green and the red Bodipy, respectively, were designed to allow the formation of efficient FRET pairs with minimal cross-talk. Organometallic dyads formed from two subunits enable the transfer of excitation energy from the donor dye to the acceptor dye. The blue, green and red emission provide three information channels on the formation of complexes, which is demonstrated for alkyne or sulfur bridged digold species and for ion pairing of a red fluorescent cation and a green fluorescent anion. This approach is extended to probe an assembly of three different subunits. In such a triad, each component is tagged with either a blue, a green or a red Bodipy and the energy transfer blue →green → red proves the formation of the triad. The tagging of molecular components with robust fluorophores can be a general strategy in (organometallic) chemistry to establish connectivities for binuclear catalyst resting states and binuclear catalyst decomposition products in homogeneous catalysis.
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Affiliation(s)
- Yoshinao Shinozaki
- Organometallic Chemistry, Technical University of DarmstadtAlarich-Weiss-Str. 1264287 DarmstadtGermany
| | - Stepan Popov
- Organometallic Chemistry, Technical University of DarmstadtAlarich-Weiss-Str. 1264287 DarmstadtGermany
| | - Herbert Plenio
- Organometallic Chemistry, Technical University of DarmstadtAlarich-Weiss-Str. 1264287 DarmstadtGermany
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8
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Gu K, Liu S, Liu C. Surface Preparation for Single-Molecule Fluorescence Imaging in Organic Solvents. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:15848-15857. [PMID: 36475684 DOI: 10.1021/acs.langmuir.2c02828] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
The development of single-molecule techniques provides opportunities to investigate the properties and heterogeneities of individual molecules, which are almost impossible to be obtained in ensemble measurements. Recently, single-molecule fluorescence microscopy is being applied more and more to study chemical reactions in organic solvents. However, little has been done to optimize the surface preparation procedures for single-molecule fluorescence imaging in organic solvents. In this work, we developed a method to prepare the surface for single-molecule fluorescence imaging in organic solvents with a well-controlled surface density of chemically immobilized dye molecules and a low density of nonspecifically adsorbed impurities. We also compared the surfaces prepared by two different procedures and studied the impacts of the polarities of the solvent and the surface functionality on the quality of prepared surface. We found that higher polarities of both the solvent and the surface functionality provided better control of the surface density of chemically immobilized dyes and helped reduce the nonspecific adsorption of both dyes and fluorescent impurities in organic solvents. We further performed single-molecule fluorescence imaging in DMF and investigated the photophysical properties of dyes and fluorescent impurities, which could be used to filter out false counts in single-molecule fluorescence measurements.
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Affiliation(s)
- Kai Gu
- School of Polymer Science and Polymer Engineering, The University of Akron, Akron, Ohio 44325, United States
| | - Shuzhen Liu
- School of Polymer Science and Polymer Engineering, The University of Akron, Akron, Ohio 44325, United States
| | - Chunming Liu
- School of Polymer Science and Polymer Engineering, The University of Akron, Akron, Ohio 44325, United States
- Department of Chemistry, The University of Akron, Akron, Ohio 44325, United States
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9
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Baral S, Liu C, Mao X, Coates GW, Chen P. Tuning Single-Polymer Growth via Hydrogen Bonding in Conformational Entanglements. ACS CENTRAL SCIENCE 2022; 8:1116-1124. [PMID: 36032769 PMCID: PMC9413429 DOI: 10.1021/acscentsci.2c00415] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Synthetic polymers have widespread applications in daily life and advanced materials applications. Making polymers efficiently and controllably is highly desired, for which modulating intramolecular and intermolecular interactions have been an effective approach. Recent real-time single-polymer growth studies uncovered nonequilibrium conformational entanglements that form stochastically under living polymerization conditions and which appear to plausibly play key roles in controlling the polymerization kinetics and dispersion. Here, using magnetic tweezers measurements, we study the real-time polymerization dynamics of single polynorbornene-based polymers in which we systematically tune the hydrogen-bonding interactions by titrating the OH content in the monomers and the formed polymers during ring opening metathesis polymerization. Using norbornenes with and without a hydroxyl group and a nonreactive monomer analogue, we show that intrachain and intermolecular hydrogen bonding compete, and both alter the microscopic properties of the nonequilibrium entanglements, leading to surprising multiphasic dependences of polymerization dynamics on the polymer's OH content. We further formulate a simple model to rationalize quantitatively the observed multiphasic behaviors by considering the different scaling relations of intrachain and intermolecular hydrogen bonding on the OH content. These results provide insights into the interconnected roles of intra-/intermolecular interactions, polymer chain conformations, and free monomers in solution in affecting polymerization kinetics and dispersion, and point to new opportunities in manipulating polymerization reactions.
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Affiliation(s)
- Susil Baral
- Department
of Chemistry and Chemical Biology, Cornell
University, Ithaca, New York 14853, United
States
| | - Chunming Liu
- Department
of Chemistry and Chemical Biology, Cornell
University, Ithaca, New York 14853, United
States
- Departments
of Polymer Science and Chemistry, The University
of Akron, Akron, Ohio 44325-3909, United States
| | - Xianwen Mao
- Department
of Chemistry and Chemical Biology, Cornell
University, Ithaca, New York 14853, United
States
| | - Geoffrey W. Coates
- Department
of Chemistry and Chemical Biology, Cornell
University, Ithaca, New York 14853, United
States
| | - Peng Chen
- Department
of Chemistry and Chemical Biology, Cornell
University, Ithaca, New York 14853, United
States
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10
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Eivgi O, Blum SA. Real-Time Polymer Viscosity-Catalytic Activity Relationships on the Microscale. J Am Chem Soc 2022; 144:13574-13585. [PMID: 35866383 DOI: 10.1021/jacs.2c03711] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Polymer growth induces physical changes to catalyst microenvironments. Here, these physical changes are quantified in real time and are found to influence microscale chemical catalysis and the polymerization rate. By developing a method to "peer into" optically transparent living-polymer particles, simultaneous imaging of both viscosity changes and chemical activity was achieved for the first time with high spatiotemporal resolution through a combination of fluorescence intensity microscopy and fluorescence lifetime imaging microscopy techniques. Specifically, an increase in microenvironment viscosity led to a corresponding local decrease in the catalytic molecular ruthenium ring-opening metathesis polymerization rate, plausibly by restricting diffusional access to active catalytic centers. Consistent with this diffusional-access model, these viscosity changes were found to be monomer-dependent, showing larger changes in microenvironment viscosity in cross-linked polydicyclopentadiene compared to non-crosslinked polynorbornene. The sensitivity and high spatial resolution of the imaging technique revealed significant variations in microviscosities between different particles and subparticle regions. These revealed spatial heterogeneities would not be observable through alternative ensemble analytical techniques that provide sample-averaged measurements. The observed spatial heterogeneities provide a physical mechanism for variation in catalytic chemical activity on the microscale that may accumulate and lead to nonhomogeneous polymer properties on the bulk scale.
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Affiliation(s)
- Or Eivgi
- Department of Chemistry, University of California, Irvine, Irvine California 92697-2025, United States
| | - Suzanne A Blum
- Department of Chemistry, University of California, Irvine, Irvine California 92697-2025, United States
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11
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Saluga SJ, Dibble DJ, Blum SA. Superresolved Motions of Single Molecular Catalysts during Polymerization Show Wide Distributions. J Am Chem Soc 2022; 144:10591-10598. [PMID: 35670469 DOI: 10.1021/jacs.2c03566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The motion of single molecular ruthenium catalysts during and after single turnover events of ring-opening metathesis polymerization is imaged through single-molecule superresolution tracking with a positional accuracy of ±32 nm. This tracking is achieved through the real-time incorporation of spectrally tagged monomer units into active polymer chain ends during living polymerization; thus, by design, only active-catalyst motion is detected and imaged, without convolution by inactive catalysts. The catalysts show diverse individualistic diffusive behaviors with respect to time that persist for up to 20 s. Catalysts occupy three mobility populations: quasi-stationary (23%), intermediate (53%, 65 nm), and large (24%, 145 nm) step sizes. Differences in catalyst mobility populations also exist between individual aggregates (p < 0.001). Such differential motion indicates widely different local catalyst microenvironments during the catalytic turnover. These mobility differences are uniquely observable through single-catalyst microscopy and are not measurable through traditional ensemble analytical techniques for characterizing the behavior of molecular catalysts, such as nuclear magnetic resonance spectroscopy. The measured distributions of active molecular catalyst motions would not be readily predictable through modeling or first-principles, and the range likely impacts individual catalyst turnover rate and selectivity. This range plausibly contributes to property distributions observable in bulk polymers, such as molecular weight polydispersity (e.g., 1.9 in this system), leading to a revised understanding of the mechanistic, microscale origins of macroscale polymer properties.
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Affiliation(s)
- Shannon J Saluga
- Department of Chemistry, University of California, Irvine, California 92697-2025, United States
| | - David Josh Dibble
- Department of Chemistry, University of California, Irvine, California 92697-2025, United States
| | - Suzanne A Blum
- Department of Chemistry, University of California, Irvine, California 92697-2025, United States
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12
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Nazarova AL, Zayat B, Fokin VV, Narayan SR. Electrochemical Studies of the Cycloaddition Activity of Bismuth(III) Acetylides Towards Organic Azides Under Copper(I)-Catalyzed Conditions. Front Chem 2022; 10:830237. [PMID: 36204144 PMCID: PMC9531323 DOI: 10.3389/fchem.2022.830237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 01/13/2022] [Indexed: 11/21/2022] Open
Abstract
Time-dependent monitoring of the reactive intermediates provides valuable information about the mechanism of a synthetic transformation. However, the process frequently involves intermediates with short lifetimes that significantly challenge the accessibility of the desired kinetic data. We report in situ cyclic voltammetry (CV) and nuclear magnetic resonance (NMR) spectroscopy studies of the cycloaddition reaction of organobismuth(III) compounds with organic azides under the copper(I)-catalyzed conditions. A series of bismuth(III) acetylides carrying diphenyl sulfone scaffolds have been synthesized to study the underlying electronic and steric effects of the tethered moieties capable of transannular oxygen O···Bi interactions and para-functionality of the parent phenylacetylene backbones. While belonging to the family of copper-catalyzed azide-alkyne cycloaddition reactions, the reaction yielding 5-bismuth(III)-triazolide is the sole example of a complex catalytic transformation that features activity of bismuth(III) acetylides towards organic azides under copper(I)-catalyzed conditions. Stepwise continuous monitoring of the copper(I)/copper(0) redox activity of the copper(I) catalyst by cyclic voltammetry provided novel insights into the complex catalytic cycle of the bismuth(III)-triazolide formation. From CV-derived kinetic data, reaction rate parameters of the bismuth(III) acetylides coordination to the copper(I) catalyst (KA) and equilibrium concentration of the copper species [cat]eq. are compared with the overall 5-bismuth(III)-triazolide formation rate constant kobs obtained by 1H-NMR kinetic analysis.
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Affiliation(s)
- Antonina L. Nazarova
- Department of Chemistry, Loker Hydrocarbon Research Institute, University of Southern California, Los Angeles, CA, United States
- Bridge Institute, USC Michelson Center for Convergent Bioscience, University of Southern California, Los Angeles, CA, United States
| | - Billal Zayat
- Department of Chemistry, Loker Hydrocarbon Research Institute, University of Southern California, Los Angeles, CA, United States
| | - Valery V. Fokin
- Department of Chemistry, Loker Hydrocarbon Research Institute, University of Southern California, Los Angeles, CA, United States
- Bridge Institute, USC Michelson Center for Convergent Bioscience, University of Southern California, Los Angeles, CA, United States
- *Correspondence: Valery V. Fokin, ; Sri R. Narayan,
| | - Sri R. Narayan
- Department of Chemistry, Loker Hydrocarbon Research Institute, University of Southern California, Los Angeles, CA, United States
- *Correspondence: Valery V. Fokin, ; Sri R. Narayan,
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13
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14
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Easter QT. Biopolymer hydroxyapatite composite materials: Adding fluorescence lifetime imaging microscopy to the characterization toolkit. NANO SELECT 2021. [DOI: 10.1002/nano.202100014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Affiliation(s)
- Quinn T. Easter
- Department of Innovation and Technology Research ADA Science & Research Institute Gaithersburg MD USA
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15
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Baral S, Liu C, Chakraborty UK, Kubo K, Mao X, Coates GW, Chen P. Single-chain polymerization dynamics and conformational mechanics of conjugated polymers. Chem 2021. [DOI: 10.1016/j.chempr.2021.05.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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16
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17
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Wang B, Lanterna AE, Scaiano JC. Mechanistic Insights on the Semihydrogenation of Alkynes over Different Nanostructured Photocatalysts. ACS Catal 2021. [DOI: 10.1021/acscatal.0c05233] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Bowen Wang
- Department of Chemistry and Biomolecular Sciences and Centre for Advanced Materials Research, University of Ottawa, Ottawa K1N 6N5, Ontario, Canada
| | - Anabel E. Lanterna
- Department of Chemistry and Biomolecular Sciences and Centre for Advanced Materials Research, University of Ottawa, Ottawa K1N 6N5, Ontario, Canada
| | - Juan C. Scaiano
- Department of Chemistry and Biomolecular Sciences and Centre for Advanced Materials Research, University of Ottawa, Ottawa K1N 6N5, Ontario, Canada
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18
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Garcia A, Saluga SJ, Dibble DJ, López PA, Saito N, Blum SA. Does Selectivity of Molecular Catalysts Change with Time? Polymerization Imaged by Single‐Molecule Spectroscopy. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202010101] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Antonio Garcia
- Department of Chemistry University of California, Irvine Irvine CA 92697-2025 USA
| | - Shannon J. Saluga
- Department of Chemistry University of California, Irvine Irvine CA 92697-2025 USA
| | - David J. Dibble
- Department of Chemistry University of California, Irvine Irvine CA 92697-2025 USA
| | - Pía A. López
- Department of Chemistry University of California, Irvine Irvine CA 92697-2025 USA
| | - Nozomi Saito
- Department of Chemistry University of California, Irvine Irvine CA 92697-2025 USA
| | - Suzanne A. Blum
- Department of Chemistry University of California, Irvine Irvine CA 92697-2025 USA
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19
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Gehlen MH, Foltran LS, Kienle DF, Schwartz DK. Single-Molecule Observations Provide Mechanistic Insights into Bimolecular Knoevenagel Amino Catalysis. J Phys Chem Lett 2020; 11:9714-9724. [PMID: 33136415 DOI: 10.1021/acs.jpclett.0c03030] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
While single-molecule (SM) methods have provided new insights to various catalytic processes, bimolecular reactions have been particularly challenging to study. Here, the fluorogenic Knoevenagel condensation of an aromatic aldehyde with methyl cyanoacetate promoted by surface-immobilized piperazine is quantitatively characterized using super-resolution fluorescence imaging and stochastic analysis using hidden Markov modeling (HMM). Notably, the SM results suggest that the reaction follows the iminium intermediate pathway before the formation of a fluorescent product with intramolecular charge-transfer character. Moreover, the overall process is limited by the turnover rate of the catalyst, which is involved in multiple steps along the reaction coordinate.
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Affiliation(s)
- Marcelo H Gehlen
- Department of Physical Chemistry, Institute of Chemistry of São Carlos, University of São Paulo, 13566-590 São Carlos, SP, Brazil
| | - Larissa S Foltran
- Department of Physical Chemistry, Institute of Chemistry of São Carlos, University of São Paulo, 13566-590 São Carlos, SP, Brazil
| | - Daniel F Kienle
- Department of Chemistry and Biological Engineering, University of Colorado, Boulder, Colorado 80309, United States
| | - Daniel K Schwartz
- Department of Chemistry and Biological Engineering, University of Colorado, Boulder, Colorado 80309, United States
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20
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Garcia A, Saluga SJ, Dibble DJ, López PA, Saito N, Blum SA. Does Selectivity of Molecular Catalysts Change with Time? Polymerization Imaged by Single‐Molecule Spectroscopy. Angew Chem Int Ed Engl 2020; 60:1550-1555. [DOI: 10.1002/anie.202010101] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 10/03/2020] [Indexed: 11/11/2022]
Affiliation(s)
- Antonio Garcia
- Department of Chemistry University of California, Irvine Irvine CA 92697-2025 USA
| | - Shannon J. Saluga
- Department of Chemistry University of California, Irvine Irvine CA 92697-2025 USA
| | - David J. Dibble
- Department of Chemistry University of California, Irvine Irvine CA 92697-2025 USA
| | - Pía A. López
- Department of Chemistry University of California, Irvine Irvine CA 92697-2025 USA
| | - Nozomi Saito
- Department of Chemistry University of California, Irvine Irvine CA 92697-2025 USA
| | - Suzanne A. Blum
- Department of Chemistry University of California, Irvine Irvine CA 92697-2025 USA
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21
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Mai DJ, Schroeder CM. 100th Anniversary of Macromolecular Science Viewpoint: Single-Molecule Studies of Synthetic Polymers. ACS Macro Lett 2020; 9:1332-1341. [PMID: 35638639 DOI: 10.1021/acsmacrolett.0c00523] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Single polymer studies have revealed unexpected and heterogeneous dynamics among identical or seemingly similar macromolecules. In recent years, direct observation of single polymers has uncovered broad distributions in molecular behavior that play a key role in determining bulk properties. Early single polymer experiments focused primarily on biological macromolecules such as DNA, but recent advances in synthesis, imaging, and force spectroscopy have enabled broad exploration of chemically diverse polymer systems. In this Viewpoint, we discuss the recent study of synthetic polymers using single-molecule methods. In terms of polymer synthesis, direct observation of single chain polymerization has revealed heterogeneity in monomer insertion events at catalytic centers and decoupling of local and global growth kinetics. In terms of single polymer visualization, recent advances in super-resolution imaging, atomic force microscopy (AFM), and liquid-cell transmission electron microscopy (LC-TEM) can resolve structure and dynamics in single synthetic chains. Moreover, single synthetic polymers can be probed in the context of bulk material environments, including hydrogels, nanostructured polymers, and crystalline polymers. In each area, we highlight key challenges and exciting opportunities in using single polymer techniques to enhance our understanding of polymer science. Overall, the expanding versatility of single polymer methods will enable the molecular-scale design and fundamental understanding of a broad range of chemically diverse and functional polymeric materials.
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Affiliation(s)
- Danielle J. Mai
- Department of Chemical Engineering, Stanford University, Stanford, California 94305, United States
| | - Charles M. Schroeder
- Department of Materials Science and Engineering, Department of Chemical and Biomolecular Engineering, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
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22
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Jess K, Hanada EM, Peacock H, Blum SA. Origins of Batch-to-Batch Variation: Organoindium Reagents from Indium Metal. Organometallics 2020; 39:2575-2579. [PMID: 33692605 DOI: 10.1021/acs.organomet.0c00417] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Yields of organoindium reagents synthesized from indium metal were previously reported to be highly dependent on metal batch and supplier due to the presence or absence of anticaking agent. Here, single-particle fluorescence microscopy established that MgO, an additive in some batches nominally for anticaking, significantly increased the physisorption of small-molecule organics onto the surface of the resulting MgO-coated indium metal particles. An inert and relatively nonpolar boron dipyrromethene fluorophore with a hydrocarbon tail provided a sensitive probe for this surface physisorption. SEM images revealed markedly different surface properties of indium particles either with or without MgO, consistent with their different physisorption properties observed by fluorescence microscopy. We further documented incomplete commercial bottle labeling regarding the presence and composition of this anticaking agent, both within our laboratory and previously in the literature, which may complicate reproducibility between laboratories. Trimethylsilyl chloride pretreatment, a step employed in a subset of reported synthetic procedures, removed the anticaking agent and produced particles with similar physisorption properties as commercial batches of indium powder distributed without the anticaking agent. These data indicate the possibility of an additional substrate/catalyst physisorption mechanism by which the anticaking agent may be influencing synthetic procedures that generate organoindium reagents from indium metal, in addition to simple anticaking.
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Affiliation(s)
- Kristof Jess
- Chemistry Department, University of California, Irvine, Irvine, CA 92697-2025
| | - Erin M Hanada
- Chemistry Department, University of California, Irvine, Irvine, CA 92697-2025
| | - Hannah Peacock
- Chemistry Department, University of California, Irvine, Irvine, CA 92697-2025
| | - Suzanne A Blum
- Chemistry Department, University of California, Irvine, Irvine, CA 92697-2025
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23
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Dogantzis NP, Hodgson GK, Impellizzeri S. Optical writing and single molecule reading of photoactivatable and silver nanoparticle-enhanced fluorescence. NANOSCALE ADVANCES 2020; 2:1956-1966. [PMID: 36132516 PMCID: PMC9418025 DOI: 10.1039/d0na00049c] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Accepted: 02/28/2020] [Indexed: 05/27/2023]
Abstract
We designed a hybrid nanoparticle-molecular system composed of silver nanostructures (AgNP) and a fluorogenic boron dipyrromethene (BODIPY) that can be selectively activated by UVA or UVC light in the presence of an appropriate photoacid generator (PAG). Light irradiation of the PAG encourages the release of p-toluenesulfonic, triflic or hydrobromic acid, any of which facilitate optical 'writing' by promoting the formation of a fluorescent species. Metal-enhanced fluorescence (MEF) by AgNP was achieved through rational design of the nano-molecular system in accordance with the principles of radiative decay engineering. In addition to increasing signal to noise, AgNP permitted shorter reaction times and low irradiance - all of which have important implications for applications of fluorescence activation in portable fluorescence patterning, bioimaging and super-resolution microscopy. Single molecule fluorescence microscopy provided unique insights into the MEF mechanism which were hidden by ensemble-averaged measurements, demonstrating that single molecule 'reading' is a valuable tool for characterizing particle-molecule interactions such as those responsible for the relative contributions of increased excitation and plasmophoric emission toward overall MEF. This work represents a step forward in the contemporary design of synergistic nano-molecular systems, and showcases the advantage of fusion between classic spectroscopic techniques and single molecule methods in terms of improved quantitative understanding of fluorophore-nanoparticle interactions, and how these interactions can be exploited to the fullest extent possible.
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Affiliation(s)
- Nicholas P Dogantzis
- Laboratory for Nanomaterials and Molecular Plasmonics, Department of Chemistry and Biology, Ryerson University 350 Victoria St. Toronto ON M5B 2K3 Canada
| | - Gregory K Hodgson
- Laboratory for Nanomaterials and Molecular Plasmonics, Department of Chemistry and Biology, Ryerson University 350 Victoria St. Toronto ON M5B 2K3 Canada
| | - Stefania Impellizzeri
- Laboratory for Nanomaterials and Molecular Plasmonics, Department of Chemistry and Biology, Ryerson University 350 Victoria St. Toronto ON M5B 2K3 Canada
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24
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Bautista-Gomez J, Usman A, Zhang M, Rafferty RJ, Bossmann SH, Hohn KL, Higgins DA. Fluorescence spectroscopy studies of crossed aldol reactions: a reactive Nile red dye reveals catalyst-dependent product formation. Catal Sci Technol 2020. [DOI: 10.1039/d0cy00806k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A highly fluorescent, aldol-reactive derivative of the dye Nile red is synthesized and evaluated as an in situ probe of crossed aldol reactions.
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Affiliation(s)
| | - Abdulhafiz Usman
- Department of Chemical Engineering
- Kansas State University
- Manhattan
- USA
| | - Man Zhang
- Department of Chemistry
- Kansas State University
- Manhattan
- USA
| | | | | | - Keith L. Hohn
- Department of Chemical Engineering
- Kansas State University
- Manhattan
- USA
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25
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Choi HK, Lee KS, Shin HH, Koo JJ, Yeon GJ, Kim ZH. Single-Molecule Surface-Enhanced Raman Scattering as a Probe of Single-Molecule Surface Reactions: Promises and Current Challenges. Acc Chem Res 2019; 52:3008-3017. [PMID: 31609583 DOI: 10.1021/acs.accounts.9b00358] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The initial observations of surface-enhanced Raman scattering (SERS) from individual molecules (single-molecule SERS, SMSERS) have triggered ever more detailed mechanistic studies on the SERS process. The studies not only reveal the existence of extremely enhanced and confined fields at the gaps of Ag or Au nanoparticles but also reveal that the spatial, spectral, and temporal behaviors of the SMSERS signal critically depend on many factors, including plasmon resonances of nanostructures, diffusion (lateral and orientational) of molecules, molecular electronic resonances, and metal-molecule charge transfers. SMSERS spectra, with their molecular vibrational fingerprints, should in principle provide molecule-specific information on individual molecules in a way that any other existing single-molecule detection method (such as the ones based on fluorescence, mechanical forces, or electrical currents) cannot. Therefore, by following the spectro-temporal evolution of SMSERS signals of reacting molecules, one should be able to follow chemical reaction events of individual molecules without any additional labels. Despite such potential, however, real applications of SMSERS for single-molecule chemistry and analytical chemistry are scarce. In this Account, we discuss whether and how we can use SMSERS to monitor single-molecule chemical kinetics. The central problem lies in the experimental challenges of separately characterizing and controlling various sources of fluctuations and spatial variations in such a way that we can extract only the chemically relevant information from time-varying SMSERS signals. This Account is organized as follows. First, we outline the standard theory of SMSERS, providing an essential guide for identifying sources of spatial heterogeneity and temporal fluctuations in SMSERS signals. Second, we show how single-molecule reaction events of surface-immobilized reactants manifest themselves in experimental SMSERS trajectories. Comparison of the reactive SMSERS data (magnitudes and frequencies of discrete transitions) and the predictions of SMSERS models also allow us to assess how faithfully the SMSERS models represent reality. Third, we show how SMSERS spectral features can be used to discover new reaction intermediates and to interrogate metal-molecule electronic interactions. Finally, we propose possible improvements in experimental design (including nanogap structures and molecular systems) to make SMSERS applicable to a broader range of chemical reactions occurring under ambient conditions. The specific examples discussed in this Account are centered around the single-molecule photochemistry of 4-nitrobenzenethiol on metals, but the conclusions drawn from each example are generally applicable to any reaction system involving small organic molecules.
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Affiliation(s)
- Han-Kyu Choi
- Department of Chemistry, Kunsan National University, Gunsan, Jeonbuk 54150, Korea
| | - Kang Sup Lee
- Department of Chemistry, Seoul National University, Seoul 08826, Korea
| | - Hyun-Hang Shin
- Department of Chemistry, Seoul National University, Seoul 08826, Korea
| | - Ja-Jung Koo
- Department of Chemistry, Seoul National University, Seoul 08826, Korea
| | - Gyu Jin Yeon
- Department of Chemistry, Seoul National University, Seoul 08826, Korea
| | - Zee Hwan Kim
- Department of Chemistry, Seoul National University, Seoul 08826, Korea
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