Understanding hydrogen sorption in a metal-organic framework with open-metal sites and amide functional groups

Handle URI:
http://hdl.handle.net/10754/562763
Title:
Understanding hydrogen sorption in a metal-organic framework with open-metal sites and amide functional groups
Authors:
Pham, Tony T.; Forrest, Katherine A.; Nugent, Patrick S.; Belmabkhout, Youssef ( 0000-0001-9952-5007 ) ; Luebke, Ryan ( 0000-0002-1285-3321 ) ; Eddaoudi, Mohamed ( 0000-0003-1916-9837 ) ; Zaworotko, Michael J.; Space, Brian
Abstract:
Grand canonical Monte Carlo (GCMC) studies of the mechanism of hydrogen sorption in an rht-MOF known as Cu-TPBTM are presented. The MOF is a decorated/substituted isostructural analogue to the unembellished rht-MOF, PCN-61, that was studied previously [ Forrest, K. A.J. Phys. Chem. C 2012, 116, 15538-15549. ]. The simulations were performed using three different hydrogen potentials of increasing complexity. Simulated hydrogen sorption isotherms and calculated isosteric heat of adsorption, Qst, values were in excellent agreement with the reported experimental data for only a polarizable model in one of four experimentally observed crystal structure configurations. The study demonstrates the ability of modeling to distinguish the differential sorption of distinct strucures; one configuration is found to be dominant due to favorable interactions with substrates. In addition, it was discovered that the presence of polar amide groups had a significant effect on the electrostatics of the Cu2+ ions and directs the low-pressure physisorption of hydrogen in the MOF. This is in contrast to what was observed in PCN-61, where an exterior copper ion had a higher relative charge and was the favored loading site. This tunability of the electrostatics of the copper ions via chemical substitution on the MOF framework can be explained by the presence of the negatively charged oxygen atom of the amide group that causes the interior Cu2+ ion to exhibit a higher positive charge through an inductive effect. Further, control simulations, taking advantage of the flexibility afforded by theoretical modeling, include artificially modified charges for both Cu2+ ions chosen equal to or with a higher charge on the exterior Cu2+ ion. This choice resulted in distinctly different hydrogen sorption characteristics in Cu-TPBTM with no direct sorption on the open-metal sites. Thus, this study demonstrates both the tunable nature of MOF platforms and the possibility for rational design of sorption/catalytic sites and characteristics through the active interplay of theory and experiment. The ability of accurate, carefully parametrized and transferable force fields to model and predict small molecule sorption in MOFs, even including open-metal sites, is demonstrated. © 2013 American Chemical Society.
KAUST Department:
Advanced Membranes and Porous Materials Research Center; Physical Sciences and Engineering (PSE) Division; Chemical Science Program; Functional Materials Design, Discovery and Development (FMD3)
Publisher:
American Chemical Society
Journal:
Journal of Physical Chemistry C
Issue Date:
9-May-2013
DOI:
10.1021/jp402304a
Type:
Article
ISSN:
19327447
Sponsors:
This work was supported by the National Science Foundation (Award No. CHE-1152362). Computations were performed under a XSEDE Grant (No. TG-DMR090028) to B.S. This publication is also based on work supported by Award No. FIC/2010/06, made by King Abdullah University of Science and Technology (KAUST). The authors also thank the Space Foundation (Basic and Applied Research) for partial support. The authors would like to acknowledge the use of the services provided by Research Computing at the University of South Florida. Lastly, the authors thank Professor Randy W. Larsen and his research group for interactive discussions on this project.
Appears in Collections:
Articles; Advanced Membranes and Porous Materials Research Center; Physical Sciences and Engineering (PSE) Division; Functional Materials Design, Discovery and Development (FMD3); Chemical Science Program

Full metadata record

DC FieldValue Language
dc.contributor.authorPham, Tony T.en
dc.contributor.authorForrest, Katherine A.en
dc.contributor.authorNugent, Patrick S.en
dc.contributor.authorBelmabkhout, Youssefen
dc.contributor.authorLuebke, Ryanen
dc.contributor.authorEddaoudi, Mohameden
dc.contributor.authorZaworotko, Michael J.en
dc.contributor.authorSpace, Brianen
dc.date.accessioned2015-08-03T11:04:50Zen
dc.date.available2015-08-03T11:04:50Zen
dc.date.issued2013-05-09en
dc.identifier.issn19327447en
dc.identifier.doi10.1021/jp402304aen
dc.identifier.urihttp://hdl.handle.net/10754/562763en
dc.description.abstractGrand canonical Monte Carlo (GCMC) studies of the mechanism of hydrogen sorption in an rht-MOF known as Cu-TPBTM are presented. The MOF is a decorated/substituted isostructural analogue to the unembellished rht-MOF, PCN-61, that was studied previously [ Forrest, K. A.J. Phys. Chem. C 2012, 116, 15538-15549. ]. The simulations were performed using three different hydrogen potentials of increasing complexity. Simulated hydrogen sorption isotherms and calculated isosteric heat of adsorption, Qst, values were in excellent agreement with the reported experimental data for only a polarizable model in one of four experimentally observed crystal structure configurations. The study demonstrates the ability of modeling to distinguish the differential sorption of distinct strucures; one configuration is found to be dominant due to favorable interactions with substrates. In addition, it was discovered that the presence of polar amide groups had a significant effect on the electrostatics of the Cu2+ ions and directs the low-pressure physisorption of hydrogen in the MOF. This is in contrast to what was observed in PCN-61, where an exterior copper ion had a higher relative charge and was the favored loading site. This tunability of the electrostatics of the copper ions via chemical substitution on the MOF framework can be explained by the presence of the negatively charged oxygen atom of the amide group that causes the interior Cu2+ ion to exhibit a higher positive charge through an inductive effect. Further, control simulations, taking advantage of the flexibility afforded by theoretical modeling, include artificially modified charges for both Cu2+ ions chosen equal to or with a higher charge on the exterior Cu2+ ion. This choice resulted in distinctly different hydrogen sorption characteristics in Cu-TPBTM with no direct sorption on the open-metal sites. Thus, this study demonstrates both the tunable nature of MOF platforms and the possibility for rational design of sorption/catalytic sites and characteristics through the active interplay of theory and experiment. The ability of accurate, carefully parametrized and transferable force fields to model and predict small molecule sorption in MOFs, even including open-metal sites, is demonstrated. © 2013 American Chemical Society.en
dc.description.sponsorshipThis work was supported by the National Science Foundation (Award No. CHE-1152362). Computations were performed under a XSEDE Grant (No. TG-DMR090028) to B.S. This publication is also based on work supported by Award No. FIC/2010/06, made by King Abdullah University of Science and Technology (KAUST). The authors also thank the Space Foundation (Basic and Applied Research) for partial support. The authors would like to acknowledge the use of the services provided by Research Computing at the University of South Florida. Lastly, the authors thank Professor Randy W. Larsen and his research group for interactive discussions on this project.en
dc.publisherAmerican Chemical Societyen
dc.titleUnderstanding hydrogen sorption in a metal-organic framework with open-metal sites and amide functional groupsen
dc.typeArticleen
dc.contributor.departmentAdvanced Membranes and Porous Materials Research Centeren
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
dc.contributor.departmentChemical Science Programen
dc.contributor.departmentFunctional Materials Design, Discovery and Development (FMD3)en
dc.identifier.journalJournal of Physical Chemistry Cen
dc.contributor.institutionDepartment of Chemistry, University of South Florida, 4202 East Fowler Avenue, CHE205, Tampa, FL 33620-5250, United Statesen
kaust.authorBelmabkhout, Youssefen
kaust.authorLuebke, Ryanen
kaust.authorEddaoudi, Mohameden
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