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Title: Nanoconfinement and Mass Transport in Silica Mesopores: the Role of Charge at the Single Molecule and Single Pore Levels

Abstract

Polarization-dependent single molecule tracking was employed to simultaneously probe the translational and orientational diffusion of four perylene diimide (PDI) dyes, having different lengths and charges, within the one-dimensional (1D) nanoscale pores of surfactant-templated mesoporous silica films. The wide-field fluorescence videos acquired reveal that a significant fraction of the molecules follow 1D pathways and exhibit highly polarized fluorescence, consistent with their orientational confinement. Single-frame step size distributions prepared from these data were fit to a new model that accurately describes the distribution for 1D Fickian diffusion in the presence of finite localization precision. Average diffusion coefficients obtained from mean square displacement (D MSD) data were 20–100% larger for the two uncharged PDIs compared to the charged PDIs, reflecting electrostatic interactions of the latter with oppositely charged sites on the cationic surfactant headgroups and deprotonated silanol sites on the pore walls. Polarization-dependent tracking data show that the longest uncharged PDI was most strongly confined, while the three shorter dyes were less confined. The cationic PDI produced a wobbling angle distribution that was broader than the others, suggesting it explores more of the pore diameter. In conclusion, the results provide new knowledge on the mechanisms by which the dye molecules interact with themore » pore-filling medium and the pore surfaces, helping to elucidate the factors controlling the rate of mass transport.« less

Authors:
 [1]; ORCiD logo [1]; ORCiD logo [1]
  1. Kansas State Univ., Manhattan, KS (United States)
Publication Date:
Research Org.:
Kansas State Univ., Manhattan, KS (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1593387
Grant/Contract Number:  
SC0002362
Resource Type:
Accepted Manuscript
Journal Name:
Analytical Chemistry
Additional Journal Information:
Journal Volume: 92; Journal Issue: 1; Journal ID: ISSN 0003-2700
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Single Molecule Tracking; Mesoporous Silica; Nanoconfinement; Mass Transport Mechanisms

Citation Formats

Kumarasinghe, Ruwandi, Ito, Takashi, and Higgins, Daniel A. Nanoconfinement and Mass Transport in Silica Mesopores: the Role of Charge at the Single Molecule and Single Pore Levels. United States: N. p., 2019. Web. doi:10.1021/acs.analchem.9b04589.
Kumarasinghe, Ruwandi, Ito, Takashi, & Higgins, Daniel A. Nanoconfinement and Mass Transport in Silica Mesopores: the Role of Charge at the Single Molecule and Single Pore Levels. United States. doi:10.1021/acs.analchem.9b04589.
Kumarasinghe, Ruwandi, Ito, Takashi, and Higgins, Daniel A. Tue . "Nanoconfinement and Mass Transport in Silica Mesopores: the Role of Charge at the Single Molecule and Single Pore Levels". United States. doi:10.1021/acs.analchem.9b04589.
@article{osti_1593387,
title = {Nanoconfinement and Mass Transport in Silica Mesopores: the Role of Charge at the Single Molecule and Single Pore Levels},
author = {Kumarasinghe, Ruwandi and Ito, Takashi and Higgins, Daniel A.},
abstractNote = {Polarization-dependent single molecule tracking was employed to simultaneously probe the translational and orientational diffusion of four perylene diimide (PDI) dyes, having different lengths and charges, within the one-dimensional (1D) nanoscale pores of surfactant-templated mesoporous silica films. The wide-field fluorescence videos acquired reveal that a significant fraction of the molecules follow 1D pathways and exhibit highly polarized fluorescence, consistent with their orientational confinement. Single-frame step size distributions prepared from these data were fit to a new model that accurately describes the distribution for 1D Fickian diffusion in the presence of finite localization precision. Average diffusion coefficients obtained from mean square displacement (DMSD) data were 20–100% larger for the two uncharged PDIs compared to the charged PDIs, reflecting electrostatic interactions of the latter with oppositely charged sites on the cationic surfactant headgroups and deprotonated silanol sites on the pore walls. Polarization-dependent tracking data show that the longest uncharged PDI was most strongly confined, while the three shorter dyes were less confined. The cationic PDI produced a wobbling angle distribution that was broader than the others, suggesting it explores more of the pore diameter. In conclusion, the results provide new knowledge on the mechanisms by which the dye molecules interact with the pore-filling medium and the pore surfaces, helping to elucidate the factors controlling the rate of mass transport.},
doi = {10.1021/acs.analchem.9b04589},
journal = {Analytical Chemistry},
number = 1,
volume = 92,
place = {United States},
year = {2019},
month = {11}
}

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This content will become publicly available on November 19, 2020
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