Insights into an intriguing gas sorption mechanism in a polar metal–organic framework with open-metal sites and narrow channels

Type
Article

Authors
Forrest, Katherine A.
Pham, Tony
McLaughlin, Keith
Hogan, Adam
Space, Brian

KAUST Grant Number
FIC/2010/06

Date
2014

Abstract
Simulations of H2 and CO2 sorption were performed in the metal-organic framework (MOF), [Cu(Me-4py-trz-ia)]. This MOF was recently shown experimentally to exhibit high uptake for H2 and CO2 sorption and this was reproduced and elucidated through the simulations performed herein. Consistent with experiment, the theoretical isosteric heat of adsorption, Qst, values were nearly constant across all loadings for both sorbates. The simulations revealed that sorption directly onto the open-metal sites was not observed in this MOF, ostensibly a consequence of the low partial positive charges of the Cu2+ ions as determined through electronic structure calculations. Sorption was primarily observed between adjacent carboxylate oxygen atoms (site 1) and between nearby methyl groups (site 2) of the organic linkers. In addition, saturation of the most energetically favorable sites (site 1) is possible only after filling a nearby site (site 2) first due to the MOF topology. This suggests that the lack of dependence on loading for the Qst is due to the concurrent filling of sites 1 and 2, leading to an observed average Qst value. © 2014 the Partner Organisations.

Citation
Forrest KA, Pham T, McLaughlin K, Hogan A, Space B (2014) Insights into an intriguing gas sorption mechanism in a polar metal–organic framework with open-metal sites and narrow channels. Chem Commun 50: 7283. Available: http://dx.doi.org/10.1039/c4cc03070b.

Acknowledgements
The authors thank Jens Moellmer and Marcus Lange for providing a copy of ref. 7, which inspired interest in modeling the MOF studied herein. The authors also thank Jens Bergmann for general discussions on this MOF. 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). In addition, the author thank the Space Foundation (Basic and Applied Research) for partial support. Lastly, the authors would like to acknowledge the use of the services provided by Research Computing at the University of South Florida.

Publisher
Royal Society of Chemistry (RSC)

Journal
Chemical Communications

DOI
10.1039/c4cc03070b

PubMed ID
24871686

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