Coordinated Water as New Binding Sites for the Separation of Light Hydrocarbons in Metal–Organic Frameworks with Open Metal Sites

Abstract

Metal−organic frameworks with open metal sites are promising materials for gas separations. Particularly, the M 2 (dobdc) (dobdc 4− = 2,5dioxidobenzenedicarboxylate, M 2+ = Co 2+ , Mn 2+ , Fe 2+ , ...) framework has been the Drosophila of this research field and has delivered groundbreaking results in terms of sorption selectivity. However, many studies focus on perfect two-component mixtures and use theoretical models, e.g., the ideal adsorbed solution theory, to calculate selectivities. Within this work, we shed light on the comparability of these selectivities with values obtained from propane/propene multicomponent measurements on the prototypical Co 2 (dobdc) framework, and we study the impact of impurities like water on the selectivity. Despite the expected capacity loss, the presence of water does not necessarily lead to a decreased selectivity. Density functional theory calculations of the binding energies prove that the water molecules adsorbed to the metal centers introduce new binding sites for the adsorbates.

Water Bridges Substitute for Defects in Amine-Functionalized UiO-66, Boosting CO2 Adsorption

“…They observed increases in CO 2 /N 2 selectivity in the presence of H 2 O, but simulations performed using MOFs preloaded with H 2 O showed decreases in CO 2 working capacities. , Rogacka et al also used molecular screening and surveyed 2932 MOFs and found 13 materials that were selective for CO 2 in the presence of water and, in many cases, the selectivity either increased, decreased, or remained unchanged depending on the amount of water present . When examining water adsorption on MOF-74, Vervoorts et al found that water adsorbed onto the metal centers in the MOF and provided a new binding site for hydrocarbon adsorbates . In addition to examining MOFs, covalent organic frameworks have also been examined with CO 2 selectivity in the presence of water …”

Quasi-Orthogonal Configuration of Propylene within a Scalable Metal–Organic Framework Enables Its Purification from Quinary Propane Dehydrogenation Byproducts

“…Note that this slight shape sieving may not achieve an ideal sieving effect, but it is important to influence the diffusion behavior of molecules. A deep insight into the Hirshfeld surface (Figure f) is that it can be observed that a highly attractive negative electrostatic potential mapped with −0.05 au (red) was clearly distributed in the pore channel, suggesting the enriched pore polarity, which favored the binding interaction with the molecule that had a larger dipole moment. , In brief, due to decent molecule dimensions and the large dipole moment of C 3 H 6 , it is expected to form strong interactions with the polar pore surface and will effortlessly diffuse into the adaptive pore channel.…”

“…In situ spectroscopies, crystallographic experiments, and modeling demonstrated that two C 3 H 6 molecules confined in one unit cell were grasped through multiple binding interaction including van der Waals effects, hydrogen bonding, and intraintermolecular interaction. Molecular dynamics showed that 1 possessed a higher diffusion selectivity of 19…”

Tuning photoactive metal–organic frameworks for luminescence and photocatalytic applications

“…[18][19][20] Additionally, the porosity of MOFs allows incorporation of various guest molecules into their voids, which can influence the properties of the materials. [21] The chemical and structural versatility of MOFs, as well as their potentially high surface areas and porosity, have facilitated their application as catalysts, [22][23][24] materials for gas storage [25] and separation, [26,27] as chemical sensors, [28,29] as photosensitisers for photodynamic therapy [30] and other applications. [31] The ability to incorporate photosensitising ligands (e.g.…”