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[Display omitted] • Big data approaches are needed to efficiently explore MOF catalyst space. • High-throughput protocols have been developed to screen large MOF datasets. • Machine learning is poised to accelerate MOF catalyst discovery. • While challenges remain, there are many recent developments and new opportunities. Metal-organic frameworks (MOFs) have been widely investigated for challenging catalytic transformations due to their well-defined structures and high degree of synthetic tunability. These features, at least in principle, make MOFs ideally suited for a computational approach towards catalyst design and discovery. Nonetheless, the widespread use of data science and machine learning to accelerate the discovery of MOF catalysts has yet to be substantially realized. In this review, we provide an overview of recent work that sets the stage for future high-throughput computational screening and machine learning studies involving MOF catalysts. This is followed by a discussion of several challenges currently facing the broad adoption of data-centric approaches in MOF computational catalysis, and we share possible solutions that can help propel the field forward. [ABSTRACT FROM AUTHOR]

Abstract: The three-point model and molecular simulation are used to understand the enantioselective adsorption of a homologous series of chiral compounds on a common chiral selector that is incorporated on a solid surface. We demonstrate how the enantioselectivity of homologous chiral compounds may go down, go up, remain the same, or even reverse. Conditions that lead to consistent enantioselectivity for homologous chiral compounds are also proposed. [Copyright &y& Elsevier]

Abstract: Metal-organic frameworks are promising materials for the capture of carbon dioxide. Finding the best metal-organic frameworks from the vast number of possibilities could be greatly accelerated by efficient computational screening techniques. We have previously reported an effective screening protocol for predicting carbon dioxide adsorption performance in metal-organic frameworks that uses grand canonical Monte Carlo simulations of gas adsorption. In the model, molecules interact via van der Waals and electrostatic interactions with each other and the framework. However, the method requires single-point quantum mechanics calculations for the estimation of atomic partial charges. In this study we investigate the feasibility of a modified protocol that bypasses the computationally expensive quantum mechanics calculations by applying instead the charge equilibration method. We compare the results of both protocols directly on fourteen metal-organic frameworks and conclude that the new protocol is sufficiently accurate for screening purposes and is significantly faster. [Copyright &y& Elsevier]

Diffusion of methane, ethane, propane and n-butane was studied within the micropores of several metal-organic frameworks (MOFs) of varying topologies, including the MOFs PCN-14, NU-125, NU-1100 and DUT-49. Diffusion coefficients of the pure components, as well as methane/ethane, methane/propane and methane/butane binary mixtures, were calculated using molecular dynamics simulations to understand the effect of the longer alkanes on uptake of natural gas in MOFs. The calculated self-diffusion coefficients of all four components are on the order of 10 −8 m 2 /s. The diffusion coefficients of the pure components decrease as a function of chain length in all of the MOFs studied and show different behaviour as a function of loading in different MOFs. The self-diffusivities follow the trend D PCN-14 NU-125≈NU-1100>DUT-49. By comparing the diffusion of pure methane and methane mixtures with the higher alkanes, it is observed that the diffusivity of methane is unaffected by the presence of the higher alkanes in the MOFs considered, indicating that the diffusion path of methane is not blocked by the higher alkanes present in natural gas. [ABSTRACT FROM AUTHOR]

Highlights: [•] Calculated hydrogen Maxwell–Stefan diffusivity in Mg-functionalized MOFs. [•] Highlighted relationship between hydrogen heat of adsorption and M–S diffusivity. [•] Showed M–S diffusivity decreases exponentially with increasing heat of adsorption. [•] Lessons from this study can be applied to diffusion in other host/guest systems. [ABSTRACT FROM AUTHOR]

Highlights: [•] MOFs with Mg alkoxide functionalizations were studied. [•] Hydrogen diffusion coefficients were obtained from MD simulations. [•] Results suggest interesting differences in diffusivities. [•] Mass transfer should be rapid in hydrogen storage applications of these materials. [ABSTRACT FROM AUTHOR]

Abstract: Molecular simulations were used to screen a diverse collection of eight homochiral metal–organic frameworks (MOFs) for their ability to separate 19 chiral compounds by enantioselective adsorption. The simulation model was validated by comparison with available experimental data. It was found that high enantioselectivity is strongly correlated with a close match between the size of the pore and the size of the chiral sorbate molecule. However, there is also a possibility of no enantioselectivity even when the size of the pore matches with the size of the chiral sorbate molecule. A four-point model was used to explain this observation, and a solution to promote high enantioselectivity has been proposed. [Copyright &y& Elsevier]

Polymorphism in metal − organic frameworks (MOFs) means that the same chemical building blocks (nodes and linkers) can be used to construct isomeric MOFs with different topological networks. The choice of topology can substantially impact the pore network of the MOF, changing the sizes and shapes of the pores, which has implications for adsorption and separation applications. In this work, we look at the influence of topology in 38 polymorphic MOFs on the separation of linear and branched C4–C6 alkane isomers, a separation of great importance to the petrochemical industry. We find that the MOF Cu 2 (1,4-benzenedicarboxylate) in nbo topology (nbo-Cu 2 BDC) has particularly high affinity for linear alkanes due to its small pore size, which excludes the branched isomers. Upon studying this MOF in further detail, we find that it can take either of two conformations: a cubic conformation, which is typical of nbo MOFs, and a unique star conformation that contains 1D triangular and hexagonal channels. The determination of which conformation the MOF will adopt depends on steric effects between the nodes and linkers. Image 1 [ABSTRACT FROM AUTHOR]

The methane deliverable capacity of adsorbent materials is a critical performance metric that will determine the viability of using adsorbed natural gas (ANG) technology in vehicular applications. ARPA-E recently set a target deliverable capacity of 315 cc(STP)/cc that a viable adsorbent material should achieve to yield a driving range competitive with incumbent fuels. However, recent computational screening of hundreds of thousands of materials suggests that the target is unattainable. In this work, we aim to determine whether the observed limits in deliverable capacity (~200 cc(STP)/cc) are fundamental limits arising from thermodynamic or material design constraints. Our efforts focus on simulating methane adsorption isotherms in a large number of systems, resulting in a broad exploration of different combinations of spatial distributions and energetics of adsorption sites. All systems were classified into five adsorption scenarios with varying degrees of realism in the manner that adsorption sites are created and endowed with energetics. The scenarios range from methane adsorption on discrete idealized lattice sites to adsorption in metal–organic frameworks with coordinatively unsaturated sites (CUS) provided by metalated catechol groups. Our findings strongly suggest that the ARPA-E target is unattainable, although not due to thermodynamic constraints but due to material design constraints. On the other hand, we also find that the currently observed deliverable capacity limits may be moderately surpassed. For instance, incorporation of CUS in IRMOF-10 is predicted to yield a 217 cc(STP)/cc deliverable capacity. The modified material has a ~0.85 void fraction and a heat of adsorption of ~15 kJ/mol. This suggests that similar, moderate improvements over existing materials could be achieved as long as CUS incorporation still maintains a relatively large void fraction. Nonetheless, we conclude that more significant improvements in deliverable capacity will require changes in the currently proposed operation conditions. [ABSTRACT FROM AUTHOR]

Highlights: [•] The geometric properties of over 137,000 hypothetical MOFs were analyzed. [•] The hypothetical MOFs have diverse geometrical properties. [•] Only 6 different framework nets appear in this database of hypothetical MOFs. [•] Energy minimization provides insights to MOF construction algorithms. [Copyright &y& Elsevier]

Abstract: Grand canonical Monte Carlo simulations were used to calculate hydrogen adsorption in IRMOF-16, NU-100, and UiO-68 functionalized with Mg or Fe catecholates on the linkers. We examined how altering the number of metal catecholate groups affects H2 uptake and deliverable capacity near ambient temperature. We find that large free volume and an isosteric heat of adsorption (Q st) of 20kJmol−1 at low loading will maximize gravimetric deliverable capacity while a small pore diameter will maximize volumetric deliverable capacity. This suggests a trade-off between the properties that lead to maximal gravimetric and volumetric capacities. For example, our calculations suggest that NU-100 functionalized with six Fe catecholate groups per linker takes up 5.5wt.% deliverable H2 at 243K and 100bar, but only 24.2gL−1 deliverable H2. [Copyright &y& Elsevier]

Abstract: Molecular simulations are known to be able to reproduce many experimental isotherms of adsorbates in the metal-organic framework IRMOF-1. Here, we show that also the positions and occupations of the adsorption sites of argon and nitrogen match well with experiments. At 30 K the molecules are localized around their crystallographic sites, while at room temperature the molecules are spread throughout the pore volume. The orientations found for individual nitrogen molecules differ from those found experimentally, although the average orientations agree well. We elucidate the pore filling mechanism for both argon and nitrogen. In addition we compute the binding energy at sites for individual argon, nitrogen, carbon dioxide, hydrogen, methane, ethane, and propane molecules and show that for all molecules the preferred site is near the zinc–oxygen cluster in the cavities where the linkers point outward. The second site, higher in energy, is near the zinc–oxygen cluster in the cavities where the linkers point inward, and the least energetically favorable site is above and beneath the linker molecule. We explain why the site in the smaller cavities is only filled up at high loadings. [Copyright &y& Elsevier]