Self-assembly of particles into long-range, three-dimensional, ordered superstructures is crucial for the design of a variety of materials, including plasmonic sensing materials, energy or gas storage systems, catalysts and photonic crystals. Here, we have combined experimental and simulation data to show that truncated rhombic dodecahedral particles of the metal-organic framework (MOF) ZIF-8 can self-assemble into millimetre-sized superstructures with an underlying three-dimensional rhombohedral lattice that behave as photonic crystals. Those superstructures feature a photonic bandgap that can be tuned by controlling the size of the ZIF-8 particles and is also responsive to the adsorption of guest substances in the micropores of the ZIF-8 particles. In addition, superstructures with different lattices can also be assembled by tuning the truncation of ZIF-8 particles, or by using octahedral UiO-66 MOF particles instead. These well-ordered, sub-micrometre-sized superstructures might ultimately facilitate the design of three-dimensional photonic materials for applications in sensing.

The use of covalent organic frameworks (COFs) in practical applications demands shaping them into macroscopic objects,which remains challenging.Herein, we report asimple three-step method to produce COF aerogels,b ased on sol-gel transition, solvent-exchange,a nd supercritical CO 2 drying, in which 2D imine-based COF sheets link together to form hierarchical porous structures.T he resultant COF aerogel monoliths have extremely lowd ensities (ca. 0.02 gcm À3 ), high porosity (total porosity values of ca. 99 %), and mechanically behave as elastic materials under am oderate strain (< 25-35 %) but become plastic under greater strain. Moreover,these COF aerogels maintain the micro-and meso-porosity of their constituent COFs,and show excellent absorption capacity (e.g. toluene uptake:3 2gg À1 ), with high removal efficiency (ca. 99 %). The same three-step method can be used to create functional composites of these COF aerogels with nanomaterials.

Enzyme-powered porous micro-and nanomotors combine self-propelled motion with tailored functionalities like adsorption and release, making them very attractive for myriad applications. Here, we report the design, synthesis and functional testing of enzyme-powered porous micromotors built from a metal-organic framework (MOF). We began by subjecting a pre-synthesized microporous UiO-type MOF to ozonolysis, to confer it with mesopores sufficiently large to adsorb and host the enzyme catalase (size: 6-10 nm). We then encapsulated catalase inside the newly-formed mesopores, observing that they are hosted in those mesopores located at the subsurface of the MOF crystals. In the presence of H2O2 fuel, our MOF motors (or MOFtors) exhibit jet-like propulsion enabled by enzymatic generation of oxygen bubbles. Moreover, thanks to their hierarchical pore system, the MOFtors retain sufficient free space for adsorption of additional targeted species, which we validated by testing a MOFtor for removal of the pollutant Rhodamine B during self-propulsion in water. Our findings will encourage future designs of porous MOF-based micro-and nanomotors for delivery, sorption and catalytic applications.

Materials with surfaces that can be switched from high/superhydrophobicity to superhydrophilicity are useful for myriad applications. Herein, we report a metal-organic framework (MOF) assembled from Zn ions, 1,4-benzenedicarboxylate, and a hydrophobic carborane-based linker. The MOF crystal-surface can be switched between hydrophobic and superhydrophilic through a chemical treatment to remove some of the building blocks.

Herein, we exploit the well-known swelling behaviour of metal-organic frameworks (MOFs) to create a self-folding polymer film. Namely, we show that incorporating crystals of the flexible MOF MIL-88A into a polyvinylidene difluoride (PVDF) matrix affords a polymer composite film that undergoes reversible shape transformations upon exposure to polar solvents and vapours. Since the self-folding properties of this film correlate directly with the swelling properties of the MIL-88A crystals, it selectively bends to certain solvents and its degree of folding can be controlled by controlling the relative humidity. Moreover, it shows a shape-memory effect at relative humidity values from 60 % to 90 %. As proof of concept, we demonstrate that these composite films can lift cargo and can be used to assemble 3D structures from 2D patterns. Our strategy is a straightforward method for designing autonomous soft materials with folding properties that can be tuned by judicious choice of the constituent flexible MOF.

Adsorptive heat transformation (AHT) systems such as adsorption thermal batteries and chillers can provide space heating and cooling in a more environmental friendly way.However, their use is still hindered by their relatively poor performances and large sizes due to the limited properties of solid adsorbents. Here, we report the spray-drying continuous-flow synthesis of a new type of solid adsorbents that results from combining metal-organic frameworks (MOFs), such as UiO-66, and hygroscopic salts, such as CaCl2. These adsorbents, commonly named as composite salt in porous matrix (CSPM) "This is the peer reviewed version of the following article: Luis Garzón-Tovar, Javier Pérez-Carvajal, Inhar Imaz. Composite Salt in Porous Metal-Organic Frameworks for Adsorption Heat Transformation, Advanced Functional Materials, 27(21): 1606424, which has been published in final form https://doi.org/10.1002/adfm.201606424. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions." 2 materials, are packed in the form of spherical superstructures/beads. In terms of water sorption properties, these composites allow improving the water uptake capabilities of MOFs while preventing their dissolution in the water adsorbed; a common characteristic of these salts due to the deliquescence effect. We anticipate that these MOF-based CSPMs, in which the percentage of salt can be tuned, are promising candidates for adsorption thermal batteries and chillers. In the first application, we show that a CSPM made of UiO-66 and CaCl2 (38 % w/w) exhibits a heat storage capacity of 367 kJ kg -1 .For adsorption chillers, we demonstrate that a second CSPM made of UiO-66 and CaCl2 (53 % w/w) shows a specific cooling power of 631 W kg -1 and a coefficient of performance of 0.83, comparable to the best solid adsorbents reported so far. INTRODUCTIONThe anthropogenic greenhouse gas emissions related to the demand of electrical energy by traditional space heating and air conditioning processes have increased over the past decade. [1] To solve this problem, several initiatives have been proposed to replace the traditional vapor compression devices by more environmentally friendly adsorptive heat transformation (AHT) systems, such as adsorption chillers, heat pumps and thermal batteries. [2] These AHT systems are based on an adsorption-desorption cycle of a working fluid, where useful heat is released during the adsorption step and cold is produced during the evaporation of the working fluid. The main advantages of these systems are (i) the possibility to use low thermal energy sources (e.g. solar and waste heat) for regeneration and driving energy; and (ii) that water can be used as the working fluid. [3]

Herein, we describe a new class of porous composites comprising metal–organic framework (MOF) crystals confined in single spherical matrices made of packed covalent‐organic framework (COF) nanocrystals. These MOF@COF composites are synthesized through a two‐step method of spray‐drying and subsequent amorphous (imine‐based polymer)‐to‐crystalline (imine‐based COF) transformation. This transformation around the MOF crystals generates micro‐ and mesopores at the MOF/COF interface that provide far superior porosity compared to that of the constituent MOF and COF components added together. We report that water sorption in these new pores occurs within the same pressure window as in the COF pores. Our new MOF@COF composites, with their additional pores at the MOF/COF interface, should have implications for the development of new composites.

The present work refers to clay-graphene nanomaterials prepared by a green way using sucrose (caramel) and two types of natural clays (montmorillonite and sepiolite) as precursors, with the aim to evaluate their potential use in hydrogen storage . The impregnation of the clay substrates by caramel in aqueous media followed by a thermal treatment in absence of oxygen of these clay-caramel intermediates gives rise to graphene-like materials, which remain strongly bound to the silicate support. The nature of the resulting materials was characterized by different techniques such as XRD, Raman spectroscopy and TEM, as well as by adsorption isotherms of N 2 , CO 2 and H 2 O.These carbon-clay nanocomposites can act as adsorbents for hydrogen storage, 2 achieving, at 298 K and 20 MPa, over 0.1 wt % of hydrogen adsorption excess related to the total mass of the system and a maximum value close to 0.4 wt % of hydrogen specifically related to the carbon mass. The very high isosteric heat for hydrogen sorption determined from adsorption isotherms at different temperatures (14.5 kJ/mol) fits well with the theoretical values available for hydrogen storage on materials which show a strong stabilization of the H 2 molecule upon adsorption.