Modeling adsorption properties of structurally deformed metal–organic frameworks using structure–property map

Abstract

Structural deformation and collapse in metal-organic frameworks (MOFs) can lead to loss of long-range order, making it a challenge to model these amorphous materials using conventional computational methods. In this work, we show that a structure-property map consisting of simulated data for crystalline MOFs can be used to indirectly obtain adsorption properties of structurally deformed MOFs. The structure-property map (with dimensions such as Henry coefficient, heat of adsorption, and pore volume) was constructed using a large data set of over 12000 crystalline MOFs from molecular simulations. By mapping the experimental data points of deformed SNU-200, MOF-5, and Ni-MOF-74 onto this structure-property map, we show that the experimentally deformed MOFs share similar adsorption properties with their nearest neighbor crystalline structures. Once the nearest neighbor crystalline MOFs for a deformed MOF are selected from a structure-property map at a specific condition, then the adsorption properties of these MOFs can be successfully transformed onto the degraded MOFs, leading to a new way to obtain properties of materials whose structural information is lost.metal-organic framework | deformation | structure-property map | Monte Carlo simulation | transferability I n the past decade, a large number of metal-organic frameworks (MOFs) have been synthesized for various energy and environmental-related applications (1-3). However, there are many potential drawbacks to these materials that need to be addressed before they can be deployed in real applications. For example, the metal ions and the organic ligands comprising the MOF structures are connected via coordination bonds that can lead to structures that possess both thermal and chemical instabilities (4, 5). As such, MOFs can readily undergo structural transformations under many circumstances, which include various thermal/vacuum treatments on activation, and exposure to air/moisture on handling, leading to irreversible damage (6-9). Although detrimental in most cases, the structural deformation can also be exploited to create strong binding sites that can enhance gas adsorption for sensing/storage purposes (10, 11).The signs of collapse and deformation of an MOF structure are usually captured by the disappearance, broadening, and/or shift of the powder X-ray diffraction (PXRD) patterns. Unfortunately, the changes observed in the PXRD peaks do not provide detailed information regarding the degree of difference between the examined MOF and its idealized parent, crystalline material. Moreover, for severe degradation where material starts to become increasingly amorphous, it becomes very difficult to model these materials using any of the conventional computational techniques such as molecular simulations due to the absence of structural information.Here, we present a conceptual platform that uses a large amount of computational data to understand and to indirectly model these deformed, amorphous MOFs even with the lack of structural information. With significant prog...

Advances, Updates, and Analytics for the Computation-Ready, Experimental Metal–Organic Framework Database: CoRE MOF 2019

“…The utility of the CoRE MOF Database has been demonstrated by its use in a growing number of computationally guided screening studies and material discovery activities (largely focused on adsorption properties of MOFs) for methane storage, natural gas storage and purification, carbon capture and separation, , Xe/Kr separation, xylene separations, olefin/paraffin separations, , conductivity, oxidative catalysis, and hexane isomer separations . Moreover, the CoRE MOF database has been used to obtain adsorption properties in deformed MOFs to predict gas adsorption properties in MOFs upon introducing defect sites and to determine the possible crystal structures of synthesized MOFs . These selected examples demonstrate that the CoRE MOF database can help researchers to discover new utility for already existing MOFs.…”

Coordination Geometry Changes in Amorphous Cyanide-Bridged Metal–Organic Frameworks upon Water Adsorption

“…Numerical simulations have also been decrease in the crystallinity upon exposure to humidity could enhance the CH 4 adsorption ability. 41 From this perspective, the potential applications of low-crystalline MOFs have been explored; however, the interpretation of their structural characteristics is still in its infancy, which sometimes prevents elucidation of the mechanisms of the structural transformations induced by external stimuli. Furthermore, the amorphous states of cyanide-bridged MOFs and their physical properties remain largely unexplored thus far.…”

Text Mining Metal–Organic Framework Papers

“…It is our anticipation that this type of effort can help the researchers within the field to (1) elucidate structure–property relationships from a large available data set, (2) provide a standardized data set to check one’s computational models, and (3) serve as a platform to pursue new ideas in the future directions for MOF research. With regards to points 1 and 2, there have been several computational screening papers on MOFs − where a wealth of experimental data sets for comparison purposes would be indeed helpful.…”