Single molecule fluorescence imaging of nanoconfinement in porous materials

Dong, Bin; Mansour, Nourhan; Huang, Teng-Xiang; Huang, Wenyu; Fang, Ning

doi:10.1039/d0cs01568g

Cited by 41 publications

(28 citation statements)

References 165 publications

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“…As a first-order approximation, a mean-field average diffusion coefficient D is sufficient to describe the permeation of molecules through a compartment at ensemble level as long as the compartment's porosity is isotropic, based on single-molecule studies of molecular diffusion in mesoporous silica and polymer films. 56,57 In the presence of anisotropicity such as highly aligned pores or in our previous work's nanowire arrays, 17,29 a mean-field averaged diffusion coefficient D is still good enough to account for the diffusion phenomena in the specific direction. 58,59 In cases where anisotropic diffusion exists, the values of anisotropic ρ normal to the compartment's boundary should be used when calculating F V .…”

Section: Resultsmentioning

confidence: 88%

A generalized kinetic model for compartmentalization of organometallic catalysis

Jolly

Davis

et al. 2022

Chem. Sci.

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Section: Resultsmentioning

confidence: 88%

A generalized kinetic model for compartmentalization of organometallic catalysis

Jolly

Davis

et al. 2022

Chem. Sci.

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“…These traditional measurement techniques, however, are incapable of measuring polymer behavior at the single-molecule and -particle level. In contrast, at the other end of the analytical regime, single-molecule/particle techniques can provide information on tethered or otherwise restricted polymer behaviors in real time with high spatial resolution, − but to date cannot measure behavior in freely diffusing solution at time scales beyond millisecond-scale snapshots or provide a way to see changes in the same species over time, leaving the solution behavior of growing polymers at the single-particle level unknown. Therefore, an analytical trade-off has existed up to this point: measure in freely diffusing solution and only acquire ensemble data or measure restricted-diffusion species and reveal single-particle/molecule data.…”

Section: Introductionmentioning

confidence: 99%

Growth Kinetics of Single Polymer Particles in Solution via Active-Feedback 3D Tracking

García

Blum

et al. 2022

J. Am. Chem. Soc.

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The ability to directly observe chemical reactions at the single-molecule and single-particle level has enabled the discovery of behaviors otherwise obscured by ensemble averaging in bulk measurements. However powerful, a common restriction of these studies to date has been the absolute requirement to surface tether or otherwise immobilize the chemical reagent/reaction of interest. This constraint arose from a fundamental limitation of conventional microscopy techniques, which could not track molecules or particles rapidly diffusing in three dimensions, as occurs in solution. However, many chemical processes occur entirely in the solution phase, leaving single-particle/-molecule analysis of this critical area of science beyond the scope of available technology. Here, we report the first kinetics studies of freely diffusing and actively growing single polymer−particles at the singleparticle level freely diffusing in solution. Active-feedback single-particle tracking was used to capture three-dimensional (3D) trajectories and real-time volumetric images of freely diffusing polymer particles (D ≈ 10 −12 m 2 /s) and extract the growth rates of individual particles in the solution phase. The observed growth rates show that the average growth rate is a poor representation of the true underlying variability in polymer−particle growth behavior. These data revealed statistically significant populations of fasterand slower-growing particles at different depths in the sample, showing emergent heterogeneity while particles are still freely diffusing in solution. These results go against the prevailing premise that chemical processes in freely diffusing solution will exhibit uniform kinetics. We anticipate that these studies will launch new directions of solution-phase, nonensemble-averaged measurements of chemical processes.

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“…Little is known experimentally about the distributions of individual-molecule translational motion during chemical reactions due to limitations in analytical techniques. Notable exceptions have been the substantial characterization of diffusion of small organic reactants and products in confined pores of catalytic zeolites and of silica core–shell nanoparticle catalysts − or on surfaces of inorganic nanoparticle- − or extended-material catalysts, where such motion is spatially restricted and easier to measure. Small-molecule molecular catalysts, in contrast, tend to diffuse faster than imaging techniques can measure and have a greater range of potential motion in three dimensions.…”

Section: Introductionmentioning

confidence: 99%

Superresolved Motions of Single Molecular Catalysts during Polymerization Show Wide Distributions

2022

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The motion of single molecular ruthenium catalysts during and after single turnover events of ring-opening metathesis polymerization is imaged through singlemolecule 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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Single molecule fluorescence imaging of nanoconfinement in porous materials

Abstract: This review surveys the application of single molecule fluorescence imaging in understanding the nanoconfinement effect in porous materials, with a focus on the mass transport behaviors and reaction dynamics during the heterogeneous catalysis.

Cited by 41 publications

References 165 publications

A generalized kinetic model for compartmentalization of organometallic catalysis

A generalized kinetic model for compartmentalization of organometallic catalysis

Growth Kinetics of Single Polymer Particles in Solution via Active-Feedback 3D Tracking

Superresolved Motions of Single Molecular Catalysts during Polymerization Show Wide Distributions

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