How Can a Hydrophobic MOF be Water-Unstable? Insight into the Hydration Mechanism of IRMOFs

Abstract : We report an ab initio Molecular Dynamics study of the hydration process in a model IRMOF material. At low water content (one molecule per unit cell), water physisorption is observed on the zinc cation but the free ⇄ bound equilibrium strongly favors the free state. This is consistent with the hydrophobic nature of the host matrix and its type V isotherm observed in a classical Monte Carlo simulation. At higher loading, a water cluster can be formed at the Zn4O site and this is shown to stabilize the water bound state. This structure very rapidly transforms into a linker-displaced state, where water has fully displaced one arm of a linker and which corresponds to the loss of the material's fully-ordered structure. Thus an overall hydrophobic MOF material can also become water unstable, a feature that was not fully understood until now.
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Submitted on : Sunday, April 28, 2019 - 10:37:21 AM
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Marta de Toni, Romain Jonchiere, Pluton Pullumbi, François-Xavier Coudert, Alain Fuchs. How Can a Hydrophobic MOF be Water-Unstable? Insight into the Hydration Mechanism of IRMOFs. ChemPhysChem, Wiley-VCH Verlag, 2012, 13 (15), pp.3497-3503. ⟨10.1002/cphc.201200455⟩. ⟨hal-02113190⟩

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