Innenrücktitelbild: Understanding CO2Dynamics in Metal-Organic Frameworks with Open Metal Sites (Angew. Chem. 16/2013)

Metal−organic frameworks (MOFs) with coordinatively unsaturated metal sites are appealing as adsorbent materials due to their tunable functionality and ability to selectively bind small molecules. Through the use of computational screening methods based on periodic density functional theory, we investigate O2 and N2 adsorption at the coordinatively unsaturated metal sites of several MOF families. A variety of design handles are identified that can be used to modify the redox activity of the metal centers, including changing the functionalization of the linkers (replacing oxido donors with sulfido donors), anion exchange of bridging ligands (considering μ-Br-, μ-Cl-, μ-F-, μ-SH-, or μ-OH- groups), and altering the formal oxidation state of the metal. As a result, we show that it is possible to tune the O2 affinity at the open metal sites of MOFs for applications involving the strong and/or selective binding of O2. In contrast with O2 adsorption, N2 adsorption at open metal sites is predicted to be relatively weak across the MOF dataset, with the exception of MOFs containing synthetically elusive V2+ open metal sites. As one example from the screening study, we predict that exchanging the μ-Cl- ligands of M2Cl2(BBTA) (H2BBTA = 1H,5H-benzo(1,2-d:4,5-d′)bistriazole) with μ-OH- groups would significantly enhance the strength of O2 adsorption at the open metal sites without a corresponding increase in the N2 affinity. Experimental investigation of Co2Cl2(BBTA) and Co2(OH)2(BBTA) confirms that the former exhibits only weak physisorption, whereas the latter is capable of chemisorbing O2 at room temperature. The chemisorption behavior is attributed to the greater electron-donating character of the μ-OH- ligands and the presence of H-bonding interactions between the μ-OH- bridging ligands and the O2 adsorbate.

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Adsorption of CO, CO2 and CH4 on Cu-BTC and MIL-101 metal organic frameworks: Effect of open metal sites and adsorbate polarity

Microporous and Mesoporous Materials ◽

10.1016/j.micromeso.2011.11.022 ◽

2012 ◽

Vol 152 ◽

pp. 246-252 ◽

Cited By ~ 119

Author(s):

Pradip Chowdhury ◽

Samuel Mekala ◽

Frieder Dreisbach ◽

Sasidhar Gumma

Keyword(s):

Metal Organic Frameworks ◽

Open Metal Sites ◽

Metal Organic ◽

Adsorption Of Co

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Using Site Heterogeneity in Metal–Organic Frameworks with Bimetallic Open Metal Sites for Olefin/Paraffin Separations

ACS Applied Nano Materials ◽

10.1021/acsanm.0c00693 ◽

2020 ◽

Vol 3 (6) ◽

pp. 5291-5300

Author(s):

Wenqin You ◽

Trisha Sen ◽

Yoshiaki Kawajiri ◽

Matthew J. Realff ◽

David S. Sholl

Keyword(s):

Metal Organic Frameworks ◽

Open Metal Sites ◽

Site Heterogeneity ◽

Metal Organic

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Retrofitting metal-organic frameworks

Nature Communications ◽

10.1038/s41467-019-12876-1 ◽

2019 ◽

Vol 10 (1) ◽

Cited By ~ 4

Author(s):

Christian Schneider ◽

David Bodesheim ◽

Julian Keupp ◽

Rochus Schmid ◽

Gregor Kieslich

Keyword(s):

Thermal Expansion ◽

Low Cost ◽

Metal Organic Framework ◽

Metal Organic Frameworks ◽

Computational Framework ◽

Expansion Behavior ◽

Open Metal Sites ◽

Metal Organic ◽

Set Up ◽

Linker Molecules

Abstract The post-synthetic installation of linker molecules between open-metal sites (OMSs) and undercoordinated metal-nodes in a metal-organic framework (MOF) — retrofitting — has recently been discovered as a powerful tool to manipulate macroscopic properties such as the mechanical robustness and the thermal expansion behavior. So far, the choice of cross linkers (CLs) that are used in retrofitting experiments is based on qualitative considerations. Here, we present a low-cost computational framework that provides experimentalists with a tool for evaluating various CLs for retrofitting a given MOF system with OMSs. After applying our approach to the prototypical system CL@Cu3BTC2 (BTC = 1,3,5-benzentricarboxylate) the methodology was expanded to NOTT-100 and NOTT-101 MOFs, identifying several promising CLs for future CL@NOTT-100 and CL@NOTT-101 retrofitting experiments. The developed model is easily adaptable to other MOFs with OMSs and is set-up to be used by experimentalists, providing a guideline for the synthesis of new retrofitted MOFs with modified physicochemical properties.

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