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The Influence of Intrinsic Framework Flexibility on Adsorption in Nanoporous Materials

[Image: see text] For applications of metal–organic frameworks (MOFs) such as gas storage and separation, flexibility is often seen as a parameter that can tune material performance. In this work we aim to determine the optimal flexibility for the shape selective separation of similarly sized molecu...

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Autores principales: Witman, Matthew, Ling, Sanliang, Jawahery, Sudi, Boyd, Peter G., Haranczyk, Maciej, Slater, Ben, Smit, Berend
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Chemical Society 2017
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5399474/
https://www.ncbi.nlm.nih.gov/pubmed/28357850
http://dx.doi.org/10.1021/jacs.7b01688
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author Witman, Matthew
Ling, Sanliang
Jawahery, Sudi
Boyd, Peter G.
Haranczyk, Maciej
Slater, Ben
Smit, Berend
author_facet Witman, Matthew
Ling, Sanliang
Jawahery, Sudi
Boyd, Peter G.
Haranczyk, Maciej
Slater, Ben
Smit, Berend
author_sort Witman, Matthew
collection PubMed
description [Image: see text] For applications of metal–organic frameworks (MOFs) such as gas storage and separation, flexibility is often seen as a parameter that can tune material performance. In this work we aim to determine the optimal flexibility for the shape selective separation of similarly sized molecules (e.g., Xe/Kr mixtures). To obtain systematic insight into how the flexibility impacts this type of separation, we develop a simple analytical model that predicts a material’s Henry regime adsorption and selectivity as a function of flexibility. We elucidate the complex dependence of selectivity on a framework’s intrinsic flexibility whereby performance is either improved or reduced with increasing flexibility, depending on the material’s pore size characteristics. However, the selectivity of a material with the pore size and chemistry that already maximizes selectivity in the rigid approximation is continuously diminished with increasing flexibility, demonstrating that the globally optimal separation exists within an entirely rigid pore. Molecular simulations show that our simple model predicts performance trends that are observed when screening the adsorption behavior of flexible MOFs. These flexible simulations provide better agreement with experimental adsorption data in a high-performance material that is not captured when modeling this framework as rigid, an approximation typically made in high-throughput screening studies. We conclude that, for shape selective adsorption applications, the globally optimal material will have the optimal pore size/chemistry and minimal intrinsic flexibility even though other nonoptimal materials’ selectivity can actually be improved by flexibility. Equally important, we find that flexible simulations can be critical for correctly modeling adsorption in these types of systems.
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spelling pubmed-53994742017-04-23 The Influence of Intrinsic Framework Flexibility on Adsorption in Nanoporous Materials Witman, Matthew Ling, Sanliang Jawahery, Sudi Boyd, Peter G. Haranczyk, Maciej Slater, Ben Smit, Berend J Am Chem Soc [Image: see text] For applications of metal–organic frameworks (MOFs) such as gas storage and separation, flexibility is often seen as a parameter that can tune material performance. In this work we aim to determine the optimal flexibility for the shape selective separation of similarly sized molecules (e.g., Xe/Kr mixtures). To obtain systematic insight into how the flexibility impacts this type of separation, we develop a simple analytical model that predicts a material’s Henry regime adsorption and selectivity as a function of flexibility. We elucidate the complex dependence of selectivity on a framework’s intrinsic flexibility whereby performance is either improved or reduced with increasing flexibility, depending on the material’s pore size characteristics. However, the selectivity of a material with the pore size and chemistry that already maximizes selectivity in the rigid approximation is continuously diminished with increasing flexibility, demonstrating that the globally optimal separation exists within an entirely rigid pore. Molecular simulations show that our simple model predicts performance trends that are observed when screening the adsorption behavior of flexible MOFs. These flexible simulations provide better agreement with experimental adsorption data in a high-performance material that is not captured when modeling this framework as rigid, an approximation typically made in high-throughput screening studies. We conclude that, for shape selective adsorption applications, the globally optimal material will have the optimal pore size/chemistry and minimal intrinsic flexibility even though other nonoptimal materials’ selectivity can actually be improved by flexibility. Equally important, we find that flexible simulations can be critical for correctly modeling adsorption in these types of systems. American Chemical Society 2017-03-30 2017-04-19 /pmc/articles/PMC5399474/ /pubmed/28357850 http://dx.doi.org/10.1021/jacs.7b01688 Text en Copyright © 2017 American Chemical Society This is an open access article published under an ACS AuthorChoice License (http://pubs.acs.org/page/policy/authorchoice_termsofuse.html) , which permits copying and redistribution of the article or any adaptations for non-commercial purposes.
spellingShingle Witman, Matthew
Ling, Sanliang
Jawahery, Sudi
Boyd, Peter G.
Haranczyk, Maciej
Slater, Ben
Smit, Berend
The Influence of Intrinsic Framework Flexibility on Adsorption in Nanoporous Materials
title The Influence of Intrinsic Framework Flexibility on Adsorption in Nanoporous Materials
title_full The Influence of Intrinsic Framework Flexibility on Adsorption in Nanoporous Materials
title_fullStr The Influence of Intrinsic Framework Flexibility on Adsorption in Nanoporous Materials
title_full_unstemmed The Influence of Intrinsic Framework Flexibility on Adsorption in Nanoporous Materials
title_short The Influence of Intrinsic Framework Flexibility on Adsorption in Nanoporous Materials
title_sort the influence of intrinsic framework flexibility on adsorption in nanoporous materials
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5399474/
https://www.ncbi.nlm.nih.gov/pubmed/28357850
http://dx.doi.org/10.1021/jacs.7b01688
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