The Interaction of Water with MOF-5 Simulated by Molecular Dynamics

Force field parameters for use with metal-organic framework-5 (MOF-5 or IRMOF-1) are presented. Flexibility within the framework is included in this model, so that structural changes upon interaction with adsorbate molecules can be observed and quantified. The model was validated by comparing simulated lattice parameters of pure MOF-5 with X-ray diffraction results. For the first time, molecular dynamics simulations have been performed that show how water interacts with MOF-5. The framework is stable at water contents up to 2.3% by mass, but distortion in the lattice structure is already evident. At water contents of 3.9% and higher, the framework collapses because of the replacement of MOF O atoms by water O atoms in the Zn coordination shells. As a result, inorganic MOF O atoms are no longer coordinated by four Zn ions, and benzene dicarboxylate linkers are no longer tethered to Zn centers.