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The use of hybrid nanomaterials for the controlled delivery of drugs in the body has attracted great scientific attention. Indeed, much effort has been put in the experimental or theoretical screening of drug loading in different biocompatible frameworks, however, full molecular-level investigations of drug adsorption in porous structures are still scarce. Herein we aim to understand the molecular mechanisms behind the good performance of the mesoporous metal–organic framework MIL-100(Fe) with respect to the adsorption of a wide range of therapeutical drugs. To this purpose, a microscopic model was developed and further validated by comparing theoretical and experimental water isotherms and the maximum uptake of two model drugs (ibuprofen and caffeine). We have found that MIL-100(Fe) has an excellent mass uptake for the 5-fluorouracil (5-FU) anti-tumoral drug molecule despite presenting a relatively weak drug/MOF interaction. We also perform detailed studies in the adsorption mechanism and sitting of the doxorubicin (DOX) molecule and how the presence of water in the structure affects the DOX-framework interactions. The good performance of the MOF MIL-100(Fe) is closely related to the diversity of interaction sites, both hydrophobic and hydrophilic. This is a desirable feature to maximize the potential of any candidate for drug carrier.

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We report an in situ polymerization strategy to incorporate a thermo-responsive polymer, poly(N-isopropylacrylamide) (PNIPAM), with controlled loadings into the cavity of a mesoporous metal-organic framework (MOF), MIL-101(Cr). The resulting MOF/polymer composites exhibit an unprecedented temperature-triggered water capture and release behavior originating from the thermo-responsive phase transition of the PNIPAM component. This result sheds light on the development of stimuli-responsive porous adsorbent materials for water capture and heat transfer applications under relatively mild operating conditions.

International audience; Adsorption-based heat transfer (AHT) devices are promising alternatives for green energy production and (re)usage; however, they are still limited by the low performance of their benchmark adsorbent materials. Metal–organic frameworks (MOFs) have been ranked among the most promising water adsorbents for this application owing to their potential superior water uptake and moderate hydrophilicity. However, there is still a need to rationalize and understand at the microscopic scale the water adsorption performances of this family of materials to further guide the selection of the next-generation water adsorbents. In this context, a full understanding of the water adsorption mechanism in the most promising MOFs containing coordinated unsaturated sites is still highly challenging. Here, we explore the water adsorption in the mesoporous MOF MIL-100(Fe) containing coordinated unsaturated Fe(III) sites by combining advanced modeling and experimental tools. As a first stage, density functional theory calculations are performed to derive an accurate force field to describe the specific interactions between water and the coordinated unsaturated Fe(III) sites. This force field is further implemented in a grand canonical Monte Carlo scheme to simulate the water adsorption isotherm and enthalpy in the whole range of relative pressures. A validation of the microscopic models and force field parameters is gained from a very good agreement between the experimental and simulated water adsorption data. As a further step, we provide an unprecedented description of the water adsorption microscopic mechanism in this very promising AHT water adsorbent by a careful analysis of the MIL-100(Fe)/H2O interactions at low and intermediate relative pressures as well as the hydrogen bond network and cluster formation at higher relative pressure.

Adsorption-driven heat transfer devices incorporating an efficient "adsorbent-water" working pair are attracting great attention as a green and sustainable technology to address the huge global energy demands for cooling and heating. Herein, we report the improved heat transfer performance of a defective Zr fumarate metal-organic framework (MOF) prepared in a water solvent (Zr-Fum HT). This material exhibits an S-shaped water sorption isotherm (P/P0 = 0.05-0.2), excellent working capacity (0.497 mLH2O mL-1MOF) under adsorption-driven cooling/chiller working conditions (Tadsorption(ads) = 30 °C, Tcondensation (con) = 30 °C, and Tdesorption(des) = 80 °C), very high coefficient of performances for both cooling (0.83) and heating (1.76) together with a relatively low driving temperature at 80 °C, a remarkable heat storage capacity (423.6 kW h m-3MOF), and an outstanding evaporation heat (343.8 kW h m-3MOF). The level of performance of the resultant Zr-Fum HT MOF is above those of all existing benchmark water adsorbents including MOF-801 previously synthesized in the N,N-dimethylformamide solvent under regeneration at 80 °C which is accessible from the solar source. This is coupled with many other decisive advantages including green synthesis and high proven chemical and mechanical robustness. The microscopic water adsorption mechanism of Zr-Fum HT at the origin of its excellent water adsorption performance was further explored computationally based on the construction of an atomistic defective model online with the experimental data gained from a subtle combination of characterization techniques.

Storing methane in clathrates is one of the most promising alternatives for transporting natural gas (NG) as it offers similar gas densities to liquefied and compressed NG while offering lower safety risks. However, the practical use of clathrates is limited given the extremely low temperatures and high pressures necessary to form these structures. Therefore, it has been suggested to confine clathrates in nanoporous materials, as this can facilitate clathrate's formation conditions while preserving its CH4 volumetric storage. Yet, the choice of nanoporous materials to be employed as the clathrate growing platform is still rather arbitrary. Herein, we tackle this challenge in a systematic way by computationally exploring the stability of clathrates confined in alkyl-grafted silica materials with different pore sizes, ligand densities and ligand types. Based on our findings, we are able to propose key design criteria for nanoporous materials favoring the stability of a neighbouring clathrate phase, namely large pore sizes, high ligand densities, and smooth pore walls. We hope that the atomistic insight provided in this work will guide and facilitate the development of new nanomaterials designed to promote the formation of clathrates., Unravelling structure–property relationships allowing clathrate stability on hydrophobized silica pores. Cyclic and medium-sized chain alkane ligands form suitable ligands for clathrate stabilization.

Extensive research has been carried on the molecular adsorption in high surface area materials such as carbonaceous materials and MOFs as well as atomic bonded hydrogen in metals and alloys. Clathrates stand among the ones to be recently suggested for hydrogen storage. Although, the simulations predict lower capacity than the expected by the DOE norms, the additional benefits of clathrates such as low production and operational cost, fully reversible reaction, environmentally benign nature, low risk of flammability make them one of the most promising materials to be explored in the next decade. The inherent ability to tailor the properties of clathrates using techniques such as addition of promoter molecules, use of porous supports and formation of novel reverse micelles morphology provide immense scope customisation and growth. As rapidly evolving materials, clathrates promise to get as close as possible in the search of “holy grail” of hydrogen storage. This review aims to provide the audience with the background of the current developments in the solid-state hydrogen storage materials, with a special focus on the hydrogen clathrates. The in-depth analysis of the hydrogen clathrates will be provided beginning from their discovery, various additives utilised to enhance their thermodynamic and kinetic properties, challenges in the characterisation of hydrogen in clathrates, theoretical developments to justify the experimental findings and the upscaling opportunities presented by this system. The review will present state of the art in the field and also provide a global picture for the path forward. Extensive research has been carried on the molecular adsorption in high surface area materials such as carbonaceous materials and MOFs as well as atomic bonded hydrogen in metals and alloys. Clathrates stand among the ones to be recently suggested for hydrogen storage. Although, the simulations predict lower capacity than the expected by the DOE norms, the additional benefits of clathrates such as low production and operational cost, fully reversible reaction, environmentally benign nature, low risk of flammability make them one of the most promising materials to be explored in the next decade. The inherent ability to tailor the properties of clathrates using techniques such as addition of promoter molecules, use of porous supports and formation of novel reverse micelles morphology provide immense scope customisation and growth. As rapidly evolving materials, clathrates promise to get as close as possible in the search of “holy grail” of hydrogen storage. This review aims to provide the audience with the background of the current developments in the solid-state hydrogen storage materials, with a special focus on the hydrogen clathrates. The in-depth analysis of the hydrogen clathrates will be provided beginning from their discovery, various additives utilised to enhance their thermodynamic and kinetic properties, challenges in the characterisation of hydrogen in clathrates, theoretical developments to justify the experimental findings and the upscaling opportunities presented by this system. The review will present state of the art in the field and also provide a global picture for the path forward. ispartof: Energy Storage Materials vol:41 pages:69-107 status: published

The molecular connectivity of polymer-metal-organic framework (polyMOF) hybrid materials was investigated using density functional theory calculations and solid-state NMR spectroscopy. The architectural constraints that dictate the formation of polyMOFs were assessed by examining poly(1,4-benzenedicarboxylic acid) (pbdc) polymers in two archetypical MOF lattices (UiO-66 and IRMOF-1). Modeling of the polyMOFs showed that in the IRMOF-1-type lattice, six, seven, and eight methylene (-CH2-) groups between 1,4-benzenedicarboxylate (terephthalate, bdc2-) units can be accommodated without significant distortions, while in the UiO-66-type lattice, an optimal spacing of seven methylene groups between bdc2- units is needed to minimize strain. Solid-state NMR supports these predictions and reveals pronounced spectral differences for the same polymer in the two polyMOF lattices. With seven methylene groups, polyUiO-66-7a shows 7 ± 3% of uncoordinated terephthalate linkers, while these are undetectable (

Summary The Sc(III) MOF-type MFM-300(Sc) is demonstrated in this study to be stable under physiological conditions (PBS), biocompatible (to human skin cells), and an efficient drug carrier for the long-term controlled release (through human skin) of antioxidant ferulate. MFM-300(Sc) also preserves the antioxidant pharmacological effects of ferulate while enhancing the bio-preservation of dermal skin fibroblasts, during the delivery process. These discoveries pave the way toward the extended use of Sc(III)-based MOFs as drug delivery systems (DDSs)., Graphical Abstract, Highlights • MFM-300(Sc) presents good stability and biocompatibility • FER@MFM-300(Sc) allows the long-term transdermal release of ferulate (FER–) • FER@MFM-300(Sc) prevents the photodegradation of FER, Medicine; Chemistry; Inorganic Chemistry; Materials Structure

Proton conducting materials are key components in proton exchange membrane fuel cells for clean energy research. Most such conducting crystalline materials (MOFs/CPs/COFs/HOFs) show limited practical application due to the multistep synthesis of organic ligands and usage of hazardous solvents. To look for simple and highly efficient crystalline proton conducting materials, we present herein a coordination polymer, PCM-1, based on a positively charged [Co(bpy)4(H2O)2]2+ (bpy = 4,4′-bipyridine) backbone. The presence of a cationic unit, anionic nitrates, as well as coordinated and adsorbed water molecules is demonstrated to play a significant role in the water-assisted ultrahigh superprotonic conduction properties. PCM-1 displays a conductivity value of over 10−2 S cm−1 at 98% relative humidity (RH) and 80 °C without any loss of performance over multiple cycles, ranking among the most promising proton conducting materials in the domain of MOFs/CPs/COFs/HOFs. Quasi-elastic neutron scattering (QENS) and molecular simulations were further combined to gain a better understanding of these properties at the molecular level. This joint experimental/modeling study revealed water-assisted proton dynamics through the formation of a long-range H-bonded network mediated by a Teixeira jump diffusion model. Furthermore, this material was shown to be highly stable and easily scalable using a green and simple synthesis process.

A Fe-MOF was obtained from aqueous solution in high yield under reflux. The water sorption properties were studied by powder X-ray diffraction, volumetric and gravimetric sorption experiments and molecular simulations. The subsequent filling of hydrophobic and hydrophilic pores as well as the stability of the material are demonstrated.

The CO2 capture performance of InOF-1 was optimised by confining small amounts of MeOH within its micropores (MeOH@InOF-1). In comparison with fully activated InOF-1, MeOH@InOF-1 shows a 1.30 and 4.88-fold increase in CO2 capture capacity for kinetic and static isothermal CO2 adsorption experiments respectively. Density functional theory calculations coupled with forcefield based-Monte Carlo simulations revealed that such an enhancement is assigned to an increase of the degree of confinement felt by the CO2 molecules resulting from the formation of a lump at the vicinity of the μ2-OH groups since MeOH strongly interacts with these adsorption sites and is thus highly localized in this region.

International audience; Kinetic CO2 adsorption measurements in the water-stable and permanently microporous Metal–organic framework material, Mg-CUK-1, reveal a 1.8-fold increase in CO2 capture from 4.6 wt% to 8.5 wt% in the presence of 18% relative humidity. Thermodynamic CO2 uptake experiments corroborate this enhancement effect, while grand canonical Monte Carlo simulations also support the phenomenon of a humidity-induced increase in the CO2 sorption capacity in Mg-CUK-1. Molecular simulations were implemented to gain insight into the microscopic adsorption mechanism responsible for the observed CO2 sorption enhancement. These simulations indicate that the cause of increasing CO2 adsorption enthalpy in the presence of H2O is due to favorable intermolecular interactions between the co-adsorbates confined within the micropores of Mg-CUK-1.

International audience; A hydrolytically stable metal–organic framework (MOF) material, named KAUST-7′, was derived from a structural phase change of KAUST-7 upon exposure to conditions akin to protonic conduction (363 K/95% relative humidity). KAUST 7′ exhibited a superprotonic conductivity as evidenced by the impedance spectroscopic measurement revealing an exceptional conductivity up to 2.0 × 10–2 S cm–1 at 363 K and under 95% RH, a performance maintained over 7 days. Ab initio molecular dynamics simulations suggested that the water-mediated proton transport mechanism is governed by water assisted reorganization of the H-bond network involving the fluorine moieties in KAUST-7′ and the guest water molecules. The notable level of performances combined with a very good hydrolytic stability positions KAUST-7′ as a prospective proton-exchange membrane alternative to the commercial benchmark Nafion. Furthermore, the remarkable RH sensitivity of KAUST-7′ conductivity, substantially higher than previously reported MOFs, offers great opportunities for deployment as a humidity sensor.

International audience; Mg-CUK-1, an ecologically friendly material synthesised in water is found to be a high-capacity, highly reversible adsorbent for acidic gases including H2S and CO2. Furthermore, Mg-CUK-1 is demonstrated to retain long-range crystallinity upon sorption cycling; its sorption performance is maintained over multiple cycles, even in the presence of high relative humidity (95%). Reversible H2S adsorption by Mg-CUK-1 is rare among MOFs studied for this purpose to date. The joint experimental and computational studies presented here show that Mg-CUK-1 is an effective solid adsorbent for applications in the field of acid gas capture, an application that is highly relevant for the purification of many industrial gas streams.

The CO

Force field-based and ab initio molecular dynamics simulations are combined with impedance spectroscopy experiments to reveal the high proton conduction performance of a three-dimensional titanium phosphate TiIVTiIV(HPO4)4 under humidity and further elucidate the microscopic mechanism at the origin of the proton transport throughout the porosity of this solid. The molecular simulations revealed that the POH groups in the structure act as a proton source, and the proton is transported from one pore to another through the hydrogen bond network formed by water molecules and the bridging O of the solid. Propitiously, besides its superprotonic behavior with a conductivity of 1.2 × 10–3 S cm–1 at room temperature and 95% relative humidity, this material is one of the best porous solids reported to date in terms of efficiency for proton transfer with a resulting activation energy (0.13 eV) as low as that reported for Nafion commercially used as electrolyte membrane in fuel cells. Furthermore, this solid shows a ...

The accumulation of heavier alkanes is a significant drawback in the use of activated carbon for the storage of natural gas. Thus far, no predictive method has been developed that can describe bed deactivation beforehand. We propose a new methodology that uses atomistic simulation and only carbon pore size distribution as the input to predict bed deactivation caused by natural-gas alkanes. We validated our model by comparing the calculated results with experimental data for alkane monocomponent isotherms and bed deactivation for WV 1050 activated carbon. Using this methodology, we estimated bed deactivation for three other species of activated carbon (Maxsorb, BPL and Norit R1) within the values found in the literature. We then predicted the optimal pore size for achieving maximum storage capacity and for minimizing the retention of heavier fractions. The suggested method will assist both fast screening and new synthesis routes for carbonaceous materials with diminished heavier-alkane selectivity. Carbon-based adsorbents used in CO2 removal during the processing of raw natural gas can also be improved.

The proton-conduction performances of the chemically stable porous zirconium phenolate MIL-163 MOF were characterized for the first time by complex impedance spectroscopy. Whereas this large square-shaped channel-like MOF exhibits very poor conductivity under anhydrous conditions, measurements performed at 90 °C and 95% relative humidity evidenced a superprotonic behavior with a conductivity of 2.1 × 10–3 S·cm–1, among the highest values reported so far for water-stable MOFs. This experimental investigation was further supported by Monte Carlo simulations to shed light on the effects of both the guest molecules (i.e., dimethylamine and water) and the acidic protons from the constitutive inorganic chains on the conduction properties of this porous hybrid solid. It was found that the water molecules form a three-dimensional hydrogen-bond network leading to the formation of multiple pathways that bridge the acidic Zr-bonded phenol groups of the organic linker, which act as a proton source. The dimethylamine ...

In modeling of activated carbons, the pores are often assumed to be slit-shaped formed of a constant number of graphene layers. X-ray diffraction studies show that micropores are formed between stacks of different numbers of graphene layers. In this study, we investigate, through the grand canonical Monte Carlo method, the influence on the adsorbed alkanes densities of pore walls with different graphene layers thickness and the related interpore adsorbate interaction when the pore wall has only one graphene layer. All studies of thickness and interpore interaction to date were performed using the Steele 10-4-3 potential model. Instead of Steele model, we propose explicit models made up of graphene layers of discrete carbon atoms. We also investigated the sensitivity of the system to the cut-off and solid-fluid parameter. With our explicit model we found that the influence of the number of carbon layers is not significant for n>2 as previously observed by Steele model—DFT studies. The system was also insensitive to cut-off and well deep parameter variations. A new pore model with an extra dummy graphene wall was proposed to investigate the interpore interaction. The interpore interaction study with the alkanes series C1 to C4 shows that the retention capacity of heavier alkanes is the same whether for activated carbons with few layers (stronger interpore interaction) as for carbons with two or more layers (stronger solid-fluid interaction) assuming negligible surface mediation. The explicit models proposed can be successfully used in the elaboration of virtual porous carbon models to reproduce wall thickness and interpore adsorbate interactions phenomena.

Two new polymethoxylated flavonoids, 2′,5′,6′-trimethoxy-[2″,3″ : 3′,4′]furano dihydrochalcone and 2,4′,4,5-tetramethoxy-[2″,3″ : 6,7]-furanodihydroaurone, were isolated from the root barks of Lonchocarpus araripensis, along with the known compounds 3,4,5,6-tetramethoxy-[2″,3″ : 7,8]-furanoflavan, 3,6-dimethoxy-1″,1″-dimethylcromene-[2″,3″ : 7,8]-flavone, 3′,4′-methylenodioxy-5,6-dimethoxy-[2″,3″ : 7,8]-furanoflavone, 3,5,6-trimethoxy-[2″,3″ : 7,8]-furanoflavanone, 3,5,6-trimethoxy-[2″,3″ : 7,8]-furanoflavone, and 6α-hydroxy-medicarpin. The complete 1H and 13C NMR assignments of the new furan flavonoids were performed using 1D and 2D pulse sequences, including COSY, HSQC, and HMBC experiments, and comparison with spectral data for analog compounds from the literature, particularly for the new furanodihydroaurone because of several inconsistencies on the carbonyl chemical shifts from the literature. Copyright © 2008 John Wiley & Sons, Ltd.

The adsorption equilibrium of methane in PCN-14 was simulated by the Monte Carlo technique in the grand canonical ensemble. A new force field was proposed for the methane/PCN-14 system, and the temperature dependence of the molecular siting was investigated. A detailed study of the statistics of the center of mass and potential energy showed a surprising site behavior with no energy barriers between weak and strong sites, allowing open metal sites to guide methane molecules to other neighboring sites. Moreover, this study showed that a model assuming weakly adsorbing open metal clusters in PCN-14, densely populated only at low temperatures (below 150 K), can explain published experimental data. These results also explain previously observed discrepancies between neutron diffraction experiments and Monte Carlo simulations.