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In this work, we computationally explore the formation and subsequent reactivity of various iron-oxo species in the iron–triazolate framework Fe2(μ-OH)2(bbta) (H2bbta = 1H,5H-benzo(1,2-d:4,5-d′)bistriazole) for the catalytic activation of strong C–H bonds. With the direct conversion of methane to methanol as the probe reaction of interest, we use density functional theory (DFT) calculations to evaluate multiple mechanistic pathways in the presence of either N2O or H2O2 oxidants. These calculations reveal that a wide range of transition metal-oxo sites – both terminal and bridging – are plausible in this family of metal–organic frameworks, making it a unique platform for comparing the electronic structure and reactivity of different proposed active site motifs. Based on the DFT calculations, we predict that Fe2(μ-OH)2(bbta) would exhibit a relatively low barrier for N2O activation and energetically favorable formation of an [Fe(O)]2+ species that is capable of oxidizing C–H bonds. In contrast, the use of H2O2 as the oxidant is predicted to yield an assortment of bridging iron-oxo sites that are less reactive. We also find that abstracting oxo ligands can exhibit a complex mixture of both positive and negative spin density, which may have broader implications for relating the degree of radical character to catalytic activity. In general, we consider the coordinatively unsaturated iron sites to be promising for oxidation catalysis, and we provide several recommendations on how to further tune the catalytic properties of this family of metal–triazolate frameworks. [ABSTRACT FROM AUTHOR]

In the past two decades, various microporous materials have been developed as useful adsorbents for gas adsorption for a wide range of industries. Considerable efforts have been made to regulate the pore accessibility in microporous materials for the manipulation of guest molecules' admission and release. It has long been known that some microporous adsorbents suddenly become highly accessible to guest molecules at specific conditions, e.g., above a threshold pressure or temperature. This anomalous adsorption behavior results from a gating effect, where a structural variation of the adsorbent leads to an abrupt change in the gas admission. This review summarizes the mechanisms of the gating effect, which can be a result of the deformation of the framework (e.g., expansion, contraction, reorientation, and sliding of the unit cells), the vibration of the pore-keeping groups (e.g., rotation, swing, and collapse of organic linkers), and the oscillation of the pore-keeping ions (e.g. cesium, potassium, etc.). These structural variations are induced either by the host–guest interaction or by an external stimulus, such as temperature or light, and account for the gating effect at a threshold value of the stimulus. Emphasis is given to the temperature-regulated gating effect, where the critical admission temperature is dictated by the combined effect of the gate opening and thermodynamic factors and plays a key role in regulating guest admission. Molecular simulations can improve our understanding of the gate opening/closing transitions at the atomic scale and enable the construction of quantitative models to describe the gated adsorption behaviour at the macroscale level. The gating effect in porous materials has been widely applied in highly selective gas separation and offers great potential for gas storage and sensing. [ABSTRACT FROM AUTHOR]

The ubiquity of metal–organic frameworks in recent scientific literature underscores their highly versatile nature. MOFs have been developed for use in a wide array of applications, including: sensors, catalysis, separations, drug delivery, and electrochemical processes. Often overlooked in the discussion of MOF-based materials is the mass transport of guest molecules within the pores and channels. Given the wide distribution of pore sizes, linker functionalization, and crystal sizes, molecular diffusion within MOFs can be highly dependent on the MOF-guest system. In this review, we discuss the major factors that govern the mass transport of molecules through MOFs at both the intracrystalline and intercrystalline scale; provide an overview of the experimental and computational methods used to measure guest diffusivity within MOFs; and highlight the relevance of mass transfer in the applications of MOFs in electrochemical systems, separations, and heterogeneous catalysis. [ABSTRACT FROM AUTHOR]

The introduction of metal alkoxides has been proposed as an attractive option to enhance hydrogen binding energies in porous materials such as metal–organic frameworks (MOFs) for room-temperature hydrogen storage applications. The presence of residual solvent molecules from MOF synthesis can, however, affect the performance of these functional groups. We perform quantum chemical calculations to predict solvent binding energies onto the metal-alkoxides and the temperatures required to drive off the solvent molecules and successfully activate porous materials with these moieties. Calculations are performed for Li, Mg, Zn, Cu, and Ni alkoxides and chloroform (CHCl3), dimethylformamide (DMF), ethanol, methanol, and water solvent molecules. We identify CHCl3 as a promising solvent that can be removed from these alkoxides at mild temperatures, whereas DMF binds strongly to the metal alkoxides and removal would require temperatures above the present upper bound of thermal stability in MOFs. As a second objective, we calculated the binding energies of hydrogen to metal alkoxide–solvent complexes to explore the effect of any solvent molecules that cannot be removed. [ABSTRACT FROM AUTHOR]

A thermodynamic analysis using quantum chemical methods was carried out to identify optimal functional group candidates that can be included in metal–organic frameworks and activated carbons for the selective capture of toxic industrial chemicals (TICs) in humid air. We calculated the binding energies of 14 critical TICs plus water with a series of 10 functional groups attached to a naphthalene ring model. Using vibrational calculations, the free energies of adsorption were calculated in addition to the binding energies. Our results show that, in these systems, the binding energies and free energies follow similar trends. We identified copper(i) carboxylate as the optimal functional group (among those studied) for the selective binding of the majority of the TICs in humid air, and this functional group exhibits especially strong binding for sulfuric acid. Further thermodynamic analysis shows that the presence of water weakens the binding strength of sulfuric acid with the copper carboxylate group. Our calculations predict that functionalization of aromatic rings would be detrimental to selective capture of COCl2, CO2, and Cl2 under humid conditions. Finally, we found that forming an ionic complex, H3O+HSO4−, between H2SO4 and H2O via proton transfer is not favorable on copper carboxylate. [ABSTRACT FROM AUTHOR]

Owing to the vast diversity of linkers, nodes, and topologies, metal–organic frameworks can be tailored for specific tasks, such as chemical separations or catalysis. Accordingly, these materials have attracted significant interest for capture and/or detoxification of toxic industrial chemicals and chemical warfare agents. In this paper, we review recent experimental and computational work pertaining to the capture of several industrially-relevant toxic chemicals, including NH3, SO2, NO2, H2S, and some volatile organic compounds, with particular emphasis on the challenging issue of designing materials that selectively adsorb these chemicals in the presence of water. We also examine recent research on the capture and catalytic degradation of chemical warfare agents such as sarin and sulfur mustard using metal–organic frameworks. [ABSTRACT FROM AUTHOR]

Aiming to elucidate guest-induced structural changes in the coordination polymer CPL-2, grand canonical Monte Carlo (GCMC) simulations were used to predict CO2 loadings in this material, and the results were compared with experimental isotherms. Our calculations suggest that CPL-2 exhibits more pronounced CO2-induced structural changes than previously reported. As the initial evidence, the isotherm simulated in the previously reported CPL-2 structure (experimentally resolved from X-ray diffraction in the “as-synthesized” CPL-2) underestimated the measured CO2 loadings at high pressure, indicating that CPL-2 might undergo structural changes that enable higher pore volumes at high pressure. GCMC simulations in CPL-2 structures considering moderate unit cell expansions reported in the literature still underestimated high-pressure experimental loadings. However, considering an incremental rotation of the CPL-2 bipyridyl pillars with increasing CO2 pressure, we were able to trace the measured isotherm with the simulation data. Computational analysis shows that ligand rotation in CPL-2 enables higher pore volumes, which, in turn, accommodate more CO2 as the gas pressure increases. Desorption measurements suggest that hysteresis in the CO2 isotherm of CPL-2 may also be linked to ligand rotation, and the measured adsorption/desorption cycles show that the rotation is reversible. Based on our simulations for CPL-4 and CPL-5 and previously reported experimental data, it is likely that these materials, which differ from CPL-2 in the bipyridyl ligand, behave similarly in the presence of CO2. Our results help understand the behavior of these materials, which present the kind of structural changes that could be potentially exploited to enhance the CO2 working capacity of ultra-microporous materials for carbon capture applications. [ABSTRACT FROM AUTHOR]

Cu-MOF-74 (also known as Cu-CPO-27) was identified as a sorbent having one of the highest densities of Cu(ii) sites per unit volume. Given that Cu(ii) in the framework can be thermally activated to yield a five-coordinate Cu(ii) species, we identified this MOF as a potential candidate for maximal volumetric uptake of ammonia. To that end, the kinetic breakthrough of ammonia in Cu-MOF-74/Cu-CPO-27 was examined under both dry and humid conditions. Under dry conditions the MOF exhibited a respectable performance (2.6 vs. 2.9 NH3 per nm3 for the current record holder HKUST-1), and under 80% relative humidity, the MOF outperformed HKUST-1 (5.9 vs. 3.9 NH3 per nm3, respectively). [ABSTRACT FROM AUTHOR]

Water is an ever-present component in the air, and competitive adsorption of water is a major challenge in many applications of adsorbents, including capture of toxic industrial chemicals (TICs) from the atmosphere. For metal–organic framework (MOF) adsorbents, the presence of water often leads to major material instabilities that could limit their practical performance. MOFs displaying hydrophobic behavior might be useful in overcoming these problems. In this work, we present a new computational strategy to quickly identify hydrophobic MOFs based on their water Henry's constants. Starting with a database of 137 953 hypothetical MOFs, we identified 45 975 structures as hydrophobic based on their simulated water Henry's constants. Using grand canonical Monte Carlo simulations, we further analyzed 2777 of these hydrophobic materials whose linkers did not contain chemical functionalization. The results show insignificant water uptake in the identified MOFs, confirming their hydrophobic nature. The capability of the hydrophobic MOFs was assessed for ammonia capture under humid conditions, and analysis of the data generated from this high-throughput computational screening revealed the role of the textural properties and surface chemistry on the removal of toxic compounds. The results suggest that if materials are too hydrophilic, they adsorb too much water and show little or no selectivity towards TICs. On the other hand, if they are too hydrophobic, they adsorb too little ammonia. [ABSTRACT FROM AUTHOR]

Metal nanoparticles (NP) encapsulated by metal–organic frameworks (MOFs) are novel composite materials that have shown promise as regioselective catalysts. The regioselectivity in these materials arises from steric constraints imposed by the porous MOF structure, which limit the way molecules approach and interact with the metal surface. Here we introduce a conceptually simple DFT approach to model reactions under such steric constraints. This approach is computationally efficient and accounts for the steric constraints imposed by a MOF pore in a general way. The adsorption of reactants, intermediates, and products associated with oxidation of n-butane to 1-butanol (and 2-butanol) on clean and oxygen-covered palladium surfaces is investigated with (and without) the constraints of a pore. Reaction energies are calculated, and we find that the thermodynamic favorability of the intermediate reactions is affected by the presence of steric constraints, oxygen coverage, and the exposed crystal surface of the metal. Based on these results, the Pd(111) surface with 0.25 ML oxygen coverage and steric constraints (which could be provided by a suitable MOF) seems promising to favor the desired sequence of reactions that would lead to the conversion of n-butane to 1-butanol. [ABSTRACT FROM AUTHOR]

CO2 capture is essential for reducing the carbon footprint of coal-fired power plants. Here we show, both experimentally and computationally, a new design strategy for capturing CO2 in nanoporous adsorbents. The approach involves ‘complementary organic motifs’ (COMs), which have a precise alignment of charge densities that is complementary to the CO2 quadrupole. Two promising COMs were post-synthetically incorporated into a robust metal–organic framework (MOF) material using solvent-assisted ligand incorporation (SALI). We demonstrate that these COM-functionalized MOFs exhibit high capacity and selectivity for CO2 relative to other reported motifs. [ABSTRACT FROM AUTHOR]

There is an almost unlimited number of metal-organic frameworks (MOFs). This creates exciting opportunities but also poses a problem: how do we quickly find the best MOFs for a given application? Molecular simulations have advanced sufficiently that many MOF properties - especially structural and gas adsorption properties - can be predicted computationally, and molecular modeling techniques are now used increasingly to guide the synthesis of new MOFs. With increasing computational power and improved simulation algorithms, it has become possible to conduct high-throughput computational screening to identify promising MOF structures and uncover structure-property relations. We review these efforts and discuss future directions in this new field. [ABSTRACT FROM AUTHOR]

A series of bio-compatible metal-organic frameworks (MOFs) have been studied as potential carriers for drug delivery applications. Grand canonical Monte Carlo (GCMC) simulations were performed to study the adsorption of the model drug ibuprofen. Simulations were first validated with available experimental data for ibuprofen adsorption and release in MIL-53, MIL-100 and MIL-101. In the second stage, the study was extended to three additional MOFs with interesting properties in terms of bio-compatibility and porosity: CDMOF-1, based on edible precursors; MOF-74 containing a highly biocompatible metal (Mg); and BioMOF-100, a mesoporous MOF with extremely high pore volume. By comparing with experimental data, we show how GCMC simulation is able to predict the macroscopic performance of new porous MOFs in drug delivery applications, providing useful molecular-level insights and giving thermodynamic and structural details of the process. Adsorption isotherms, snapshots, energy of adsorption and radial distribution functions were used to analyse the drug delivery process. [ABSTRACT FROM AUTHOR]

A porous organic polymer decorated with high densities of copper(catecholate) groups was prepared and characterized. Single-component propylene and propane isotherms measured at ambient temperatures and ideal adsorption solution theory (IAST) calculations revealed increasing propylene/propane selectivities with increasing pressures. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) are permanently porous, crystalline materials and promising hydrogen sorbents. However, the H2 heats of adsorption are generally too small to promote significant adsorption under desired storage conditions. Increasing the H2–framework interaction energy is a prominent goal of current MOF design. Hydrogen binds to MOFs through a variety of interactions, such as dispersion, charge–induced-dipole, charge–quadrupole, and even chemical bonding. To date, these interactions have been enhanced by incorporating strongly charged groups into the MOF structures, but the effects tend to be short-range and only effective at low loadings. In this work we report the structures and H2 storage properties of two zwitterionic MOFs. These structures feature zwitterionic characteristics arising from N-heterocyclic azolium groups in the linkers and negatively charged Zn2(CO2)5 nodes. These groups exhibit net charges of +0.5 and −1.0, respectively, and interact strongly with the H2 quadrupole. Isosteric heats of adsorption of up to 7.0 kJ mol−1 are observed in these zwitterionic MOFs. [ABSTRACT FROM AUTHOR]

The members of a homologous series of chiral compounds often show inconsistent enantioselectivities when separated on the same chiral stationary phase. The reasons behind this are subject to debate due to the lack of an efficient way to probe the molecular level separation mechanisms on conventional chiral stationary phases. Homochiral metal–organic frameworks (HMOFs) are a family of new porous, crystalline materials that can be used as chiral stationary phases. The regular structures of HMOFs make possible the detailed interrogation of chiral separation mechanisms through molecular modeling. In this report, molecular modeling techniques were used to study the enantioselectivities of a homologous series of chiral compounds in two different HMOFs. We demonstrate that a shift in the adsorption site is one reason for the lack of a correlation between the enantioselectivities of a homologous series of chiral compounds. In addition, we demonstrate that a smooth HMOF pore can help preserve the adsorption site and the separation mechanism, and hence achieve consistent enantioselectivity for a homologous series of chiral compounds. [ABSTRACT FROM AUTHOR]

Simulated adsorption isotherms for water in UiO-66 illustrate that defects in the form of missing linkers make this MOF more hydrophilic. Heats of adsorption and density plots further confirm the effect of defects on adsorption of water in UiO-66 at low loadings. In addition, water and CO2 isotherms indicate that not only the amount of defects but their locations within the material affect the loading of guest molecules. [ABSTRACT FROM AUTHOR]

The metal-organic framework Ni-DOBDC was modified with pyridine molecules to make the normally hydrophilic internal surface more hydrophobic. Experiments and molecular simulations show that the pyridine modification reduces H2O adsorption while retaining substantial CO2 capacity under the conditions of interest for carbon capture from flue gas. [ABSTRACT FROM AUTHOR]

A scalable, reproducible method of synthesizing UiO-66- and UiO-67-type MOFs, entailing the addition of HCl to the reaction mixture, has been investigated. The new protocol requires a fraction of the time of previously reported procedures, yields exceptional porosities, and works with a range of linkers. [ABSTRACT FROM AUTHOR]

We show that the MOF NU-111 exhibits equally high volumetric and gravimetric methane uptake values, both within ≈75% of the DOE targets at 300 K. Upon reducing the temperature to 270 K, the uptake increases to 0.5 g g−1 and 284 cc(STP) per cc at 65 bar. Adsorption of CO2 and H2 is also reported. Simulated isotherms are in excellent agreement with those obtained from experiments. [ABSTRACT FROM AUTHOR]

Separations of CO2/CH4, CO2/N2, and O2/N2mixtures were studied in three porous coordination polymers made of the same carborane ligand and Co(ii) nodes. High selectivities for CO2over CH4(∼47) and CO2over N2(∼95) were obtained, especially in the material with coordinated pyridine. Unusual selectivity for O2over N2(as high as 6.5) was demonstrated in the materials with open Co(ii) sites. [ABSTRACT FROM AUTHOR]

A diimide based porous organic polymer (POP) post-synthetically reduced with lithium metal demonstrates a drastic increase in selectivity for carbon dioxide over methane. [ABSTRACT FROM AUTHOR]

Grand canonical Monte Carlo (GCMC) simulations demonstrate that catenation can be beneficial for improving hydrogen storage in metal–organic frameworks at cryogenic temperatures and low pressures but not necessarily at room temperature. [ABSTRACT FROM AUTHOR]

Separation of CO2/CH4 mixtures was studied in carborane-based metal–organic framework materials with and without coordinatively unsaturated metal sites; high selectivities for CO2 over CH4 (∼17) are obtained, especially in the material with open metal sites. [ABSTRACT FROM AUTHOR]

The introduction of metal alkoxides has been proposed as an attractive option to enhance hydrogen binding energies in porous materials such as metal-organic frameworks (MOFs) for room-temperature hydrogen storage applications. The presence of residual solvent molecules from MOF synthesis can, however, affect the performance of these functional groups. We perform quantum chemical calculations to predict solvent binding energies onto the metal-alkoxides and the temperatures required to drive off the solvent molecules and successfully activate porous materials with these moieties. Calculations are performed for Li, Mg, Zn, Cu, and Ni alkoxides and chloroform (CHCl3), dimethylformamide (DMF), ethanol, methanol, and water solvent molecules. We identify CHCl3 as a promising solvent that can be removed from these alkoxides at mild temperatures, whereas DMF binds strongly to the metal alkoxides and removal would require temperatures above the present upper bound of thermal stability in MOFs. As a second objective, we calculated the binding energies of hydrogen to metal alkoxide-solvent complexes to explore the effect of any solvent molecules that cannot be removed.

FMOF-1 is a flexible, superhydrophobic metal-organic framework with a network of channels and side pockets decorated with -CF 3 groups. CO 2 adsorption isotherms measured between 278 and 313 K and up to 55 bar reveal a maximum uptake of ca. 6.16 mol kg -1 (11.0 mol L -1 ) and unusual isotherm shapes at the higher temperatures, suggesting framework expansion. We used neutron diffraction and molecular simulations to investigate the framework expansion behaviour and the accessibility of the small pockets to N 2 , O 2 , and CO 2 . Neutron diffraction in situ experiments on the crystalline powder show that CO 2 molecules are favourably adsorbed at three distinct adsorption sites in the large channels of FMOF-1 and cannot access the small pockets in FMOF-1 at 290 K and oversaturated pressure at 61 bar. Stepped adsorption isotherms for N 2 and O 2 at 77 K can be explained by combining Monte Carlo simulations in several different crystal structures of FMOF-1 obtained from neutron and X-ray diffraction under different conditions. A similar analysis is successful for CO 2 adsorption at 278 and 283 K up to ca. 30 bar; however, at 298 K and pressures above 30 bar, the results suggest even more substantial expansion of the FMOF-1 framework. The measured contact angle for water on an FMOF-1 pellet is 158°, demonstrating superhydrophobicity. Simulations and adsorption measurements also show that FMOF-1 is hydrophobic and water is not adsorbed in FMOF-1 at room temperature. Simulated mixture isotherms of CO 2 in the presence of 80% relative humidity predict that water does not influence the CO 2 adsorption in FMOF-1, suggesting that hydrophobic MOFs could hold promise for CO 2 capture from humid gas streams.

Aiming to elucidate guest-induced structural changes in the coordination polymer CPL-2, grand canonical Monte Carlo (GCMC) simulations were used to predict CO 2 loadings in this material, and the results were compared with experimental isotherms. Our calculations suggest that CPL-2 exhibits more pronounced CO 2 -induced structural changes than previously reported. As the initial evidence, the isotherm simulated in the previously reported CPL-2 structure (experimentally resolved from X-ray diffraction in the "as-synthesized" CPL-2) underestimated the measured CO 2 loadings at high pressure, indicating that CPL-2 might undergo structural changes that enable higher pore volumes at high pressure. GCMC simulations in CPL-2 structures considering moderate unit cell expansions reported in the literature still underestimated high-pressure experimental loadings. However, considering an incremental rotation of the CPL-2 bipyridyl pillars with increasing CO 2 pressure, we were able to trace the measured isotherm with the simulation data. Computational analysis shows that ligand rotation in CPL-2 enables higher pore volumes, which, in turn, accommodate more CO 2 as the gas pressure increases. Desorption measurements suggest that hysteresis in the CO 2 isotherm of CPL-2 may also be linked to ligand rotation, and the measured adsorption/desorption cycles show that the rotation is reversible. Based on our simulations for CPL-4 and CPL-5 and previously reported experimental data, it is likely that these materials, which differ from CPL-2 in the bipyridyl ligand, behave similarly in the presence of CO 2 . Our results help understand the behavior of these materials, which present the kind of structural changes that could be potentially exploited to enhance the CO 2 working capacity of ultra-microporous materials for carbon capture applications.

Cu-MOF-74 (also known as Cu-CPO-27) was identified as a sorbent having one of the highest densities of Cu(ii) sites per unit volume. Given that Cu(ii) in the framework can be thermally activated to yield a five-coordinate Cu(ii) species, we identified this MOF as a potential candidate for maximal volumetric uptake of ammonia. To that end, the kinetic breakthrough of ammonia in Cu-MOF-74/Cu-CPO-27 was examined under both dry and humid conditions. Under dry conditions the MOF exhibited a respectable performance (2.6 vs. 2.9 NH3 per nm(3) for the current record holder HKUST-1), and under 80% relative humidity, the MOF outperformed HKUST-1 (5.9 vs. 3.9 NH3 per nm(3), respectively).

Water stability in metal-organic frameworks (MOFs) is critical for several practical applications. While water instability is mainly thought to stem from linker hydrolysis, MOFs with strong, hydrolysis-resistant metal-linker bonds can be susceptible to damage by capillary forces, which cause cavities and channels to collapse during activation from water. This study utilizes metal node functionalization as a strategy to create vapor-stable and recyclable MOFs.

CO2 capture is essential for reducing the carbon footprint of coal-fired power plants. Here we show, both experimentally and computationally, a new design strategy for capturing CO2 in nanoporous adsorbents. The approach involves 'complementary organic motifs' (COMs), which have a precise alignment of charge densities that is complementary to the CO2 quadrupole. Two promising COMs were post-synthetically incorporated into a robust metal-organic framework (MOF) material using solvent-assisted ligand incorporation (SALI). We demonstrate that these COM-functionalized MOFs exhibit high capacity and selectivity for CO2 relative to other reported motifs.

The metal-organic framework Ni-DOBDC was modified with pyridine molecules to make the normally hydrophilic internal surface more hydrophobic. Experiments and molecular simulations show that the pyridine modification reduces H2O adsorption while retaining substantial CO2 capacity under the conditions of interest for carbon capture from flue gas.

A series of bio-compatible metal-organic frameworks (MOFs) have been studied as potential carriers for drug delivery applications. Grand canonical Monte Carlo (GCMC) simulations were performed to study the adsorption of the model drug ibuprofen. Simulations were first validated with available experimental data for ibuprofen adsorption and release in MIL-53, MIL-100 and MIL-101. In the second stage, the study was extended to three additional MOFs with interesting properties in terms of bio-compatibility and porosity: CDMOF-1, based on edible precursors; MOF-74 containing a highly biocompatible metal (Mg); and BioMOF-100, a mesoporous MOF with extremely high pore volume. By comparing with experimental data, we show how GCMC simulation is able to predict the macroscopic performance of new porous MOFs in drug delivery applications, providing useful molecular-level insights and giving thermodynamic and structural details of the process. Adsorption isotherms, snapshots, energy of adsorption and radial distribution functions were used to analyse the drug delivery process.

For a series of metal-organic frameworks with rht topology, we study computationally the effect of the linker length on the surface area, pore size, and pore volume, relating them with the hydrogen adsorption properties. The results provide new insights about the excess capacities and the pressures where the uptake maxima in the excess isotherms occur. We found that, of the materials studied, has the optimal pore volume for excess gravimetric hydrogen uptake.

A series of metalloporphyrin dimers were modularly prepared and shown to catalyze the methanolysis of a phosphate triester, yielding rates that are large compared to the rate of the uncatalyzed reaction. Up to 1300-fold rate acceleration can be achieved via a combination of cavity-localized Lewis-acid activation and methoxide-induced methanolysis.

The adsorption of ammonia in four metal-organic frameworks modified with different functional groups (-OH, -C=O, -Cl, -COOH) was investigated using a hierarchical molecular modeling approach. To describe the hydrogen bonding and other strong interactions between NH(3) and the surface functional groups, a set of Morse potential parameters were obtained by fitting to energies from quantum chemical calculations at the MP2 level of theory. We describe a systematic force field parameterization process, in which the Morse parameters were fitted using simulated annealing to match a large number of single-point MP2 energies at various distances and angles. The fitted potentials were then used in grand canonical Monte Carlo simulations to predict ammonia adsorption isotherms and heats of adsorption in functionalized MIL-47, IRMOF-1, IRMOF-10, and IRMOF-16. The results show that ammonia adsorption can be significantly enhanced by using materials with appropriate pore size, strongly interacting functional groups, and high density of functional groups.