Molecular Insight into Water Effects in a Stable Metal-Organic Framework: An in-situ Experimental and Molecular Modeling Analysis

Competitive water adsorption can have an important impact on metal-organic framework (MOF) performance properties. This can range from occupying active sites in catalytic reactions to co-adsorbing at the most favorable adsorption sites for gas separation and storage applications. The novel question addressed in this work is: for a MOF that is stable after moisture exposure, what are the reversible, loading-dependent structural changes that occur during water adsorption?

To explore this question, a combination of in situ synchrotron powder diffraction analysis and molecular simulation techniques are applied to provide insight into the important role of loading-dependent water effects in the stable Zn-DMOF-TM structure. Through this analysis, insight into changes to crystallographic lattice parameters, water siting information, and water-induced defect incorporation are obtained. Overall, this work shows that even for stable MOFs that maintain their porosity and crystallinity characteristics after water exposure, important molecular-level structural changes can still occur during water adsorption.