Molecular driving forces for water adsorption in MOF-808: A comparative analysis with UiO-66

15 December 2023, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


Metal-organic frameworks (MOFs), with their unique porous structures and versatile functionality, have emerged as promising materials for adsorption, separation, and storage of diverse molecular species. In this study, we investigate water adsorption in MOF-808, a prototypical MOF that shares the same secondary building unit (SBU) as UiO-66, and elucidate how differences in topology and connectivity between the two MOFs influence the adsorption mechanism. To this end, molecular dynamics (MD) simulations were performed to calculate several thermodynamic and dynam- ical properties of water in MOF-808 as a function of relative humidity (RH), from the initial adsorption step to full pore filling. At low RH, the μ3-OH groups of the SBUs form hydrogen bonds with the initial water molecules entering the pores, which triggers the filling of these pores before the μ3-OH groups in other pores become en- gaged in hydrogen bonding with water molecules. Our analyses indicate that the pores of MOF-808 become filled by water sequentially as the RH increases. A similar mechanism has been reported for water adsorption in UiO-66, a MOF that shares the same SBU with MOF-808. Despite this similarity, our study highlights distinct ther- modynamic properties and framework characteristics that influence the adsorption process differently in MOF-808 and UiO-66.


metal-organic frameworks
phase behavior
many-body effects
molecular interactions

Supplementary materials

Supplementary Material
Details about the molecular models used in the MD simulations along with the complete list of force field parameters used to describe the MOF-808 framework.


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