Probing the Water Stability Limits and Degradation Pathways of Metal‐Organic Frameworks (MOFs)
Safy, M.E.A. / Amin, M. / Haikal, R.R. / Elshazly, B. / Wang, J. / Wang, Y / Wöll, C. / Alkordi, M.H. (2020)
Chemistry A European Journal, 2020, doi: org/10.1002/chem.202000207
- Datum: März 2020
A comprehensive model to describe water stability of prototypal metal‐organic frameworks (MOFs) by combining different types of theoretical and experimental approaches is derived. Our results provide insight into the early stages of water‐triggered destabilization of MOFs, and allow proposing detailed pathways for the degradation of different MOFs under aqueous conditions. The essential elements of the approach are computing the pKa values of coordinated water molecules and geometry relaxations. We use variable temperature and pH infrared spectroscopy techniques to corroborate our main findings. The model developed herein helps explaining stability limits observed for several prototypal MOFs, including MOF‐5, HKUST‐1, UiO‐66, and MIL‐101‐Cr in aqueous solutions, providing insight into the possible degradation pathways in acidic and basic environment. Formation of metal‐hydroxide from autoprotolysis of metal‐coordinated water molecules, and the strength of carboxylate‐metal interactions are the two key players governing stability in basic and acidic media, respectively. The methodology presented herein can effectively guide future efforts, especially significant to in silico screening, for developing novel MOFs with enhanced aqueous stability.