Towards modeling spatiotemporal processes in metal–organic frameworks

Abstract

Metal-organic frameworks (MOFs) are hybrid materials constructed from metal clusters linked by organic linkers, which can be engineered for target functional applications in, for example, catalysis, sensing, and storage. The dynamic response of MOFs on external stimuli can be tuned by spatial heterogeneities such as defects and crystal size as well as by operating conditions such as temperature, pressure, moisture, and external fields. Modeling the spatiotemporal evolution of MOFs under operating conditions and at length and time scales comparable with experimental observations is extremely challenging. Herein, we give a status on modeling spatiotemporal processes in MOFs under working conditions and reflect on how modeling can be reconciled with in situ spectroscopy measurements. HighlightsMetal-organic frameworks (MOFs) can respond in an anomalous way to external stimuli, giving rise to dynamic bond rearrangement and/or large-amplitude structural transformations without breakage of the crystal.

Large-Scale Molecular Dynamics Simulations Reveal New Insights Into the Phase Transition Mechanisms in MIL-53(Al)

“…Previous considerations clearly illustrate the complexity associated with a full understanding of phase transformations in SPCs. The problem at hand is a prototypical example of a spatiotemporal process, where the dynamics of the MOF lattice is affected by spatial heterogeneities at various length and time scales (Van Speybroeck et al, 2021). A full understanding of the spatiotemporal response of MOFs will require a close partnership between the modeling and experimental community, whereby dedicated experimental in situ methods are necessary to track intermediate metastable states during their dynamic response towards external stimuli, and where theoreticians will have to explore new modeling avenues to tackle processes at various length and time scales.…”

“…Computational modeling can help to unravel such mechanistic details, provided that the employed models are realistic representations of experimentally observed MOFs, with dimensions comparable to real crystallites and with the explicit inclusion of the external surface and potential defects. Unfortunately, even with the massive amount of computing resources that is now available, such simulations are not yet feasible (Van Speybroeck et al, 2021). At present, the attainable length scales within the field of nanostructured materials are limited to a few nanometers and common molecular dynamics (MD) runs extend from the picoscale (for ab initio based methods) to the nanoscale range (for force field based methods).…”

“…Such spatial dimensions are still below experimental crystal sizes which may extend well into the micrometer range (see Figure 1A). As a consequence of these model limitations, some effects which are inherently related to (long-range) spatial disorder are not properly accounted for in current computational models (Van Speybroeck et al, 2021).…”

Dynamics of Heterogeneous Catalytic Processes at Operando Conditions

“…Once a successful MLP has been derived, it has the potential to be used efficiently on much larger systems than the one on which it was trained, significantly lowering the computational cost for the simulation of large-scale systems. 152 …”

Towards Predicting the Sequential Appearance of Zeolitic Imidazolate Frameworks Synthesized by Mechanochemistry

“…In other words, why, for example, were RHO-Zn(HMeIm) 2 and SOD-Zn(HEtIm) 2 not observed in the laboratory? This work aims to shed some light on this complex issue [ 16 ]. To do so, we modeled the 12 ZIFs resulting from the combination of the six topologies RHO, ANA, QTZ, SOD, KAT and DIA of sequences (2) and (3) with the two ligands HMeIm and HEtIm and searched for criteria to identify the experimentally observed ZIFs and determine their order of appearance.…”