•The methods for the preparation of metal and metal/oxide nanoparticles@MOFs are illustrated.•The different applications of metal and metal/oxide nanoparticles with MOFs are described.•New emerging ...trends in MOF composites and related challenges are disclosed.
Composites based on Metal-Organic Frameworks (MOFs) are an emerging class of porous materials that have been shown to possess unique functional properties. Nanoparticles@MOFs composites combine the tailorable porosity of MOFs with the versatile functionality of metal or metaloxide nanoparticles. A wide range of nanoparticles@MOFs have been synthesised and their performance characteristics assessed in molecular adsorption and separation, catalysis, sensing, optics, sequestration of pollutants, drug delivery, and renewable energy. This review covers the main research areas where nanoparticles@MOFs have been strategically applied and highlights the scientific challenges to be considered for their continuing development.
Controlling the shape of metal–organic framework (MOF) crystals is important for understanding their crystallization and useful for myriad applications. However, despite the many advances in shaping ...of inorganic nanoparticles, post‐synthetic shape control of MOFs and, in general, molecular crystals remains embryonic. Herein, we report using a simple wet‐chemistry process at room temperature to control the anisotropic etching of colloidal ZIF‐8 and ZIF‐67 crystals. Our work enables uniform reshaping of these porous materials into unprecedented morphologies, including cubic and tetrahedral crystals, and even hollow boxes, by an acid–base reaction and subsequent sequestration of leached metal ions. Etching tests on these ZIFs reveal that etching occurs preferentially in the crystallographic directions richer in metal–ligand bonds; that, along these directions, the etching rate tends to be faster on the crystal surfaces of higher dimensionality; and that the etching can be modulated by adjusting the pH of the etchant solution.
Post‐synthetic wet‐chemical anisotropic etching of colloidal ZIF‐8 and ZIF‐67 crystals enables uniform reshaping of them into unprecedented shapes, including cubic and tetrahedral crystals, and even hollow boxes, by an acid–base reaction and subsequent sequestration of leached metal ions.
Accurate, noninvasive, and self‐referenced temperature measurements at the submicrometer scale are of great interest, prompted by the ever‐growing demands in the fields of nanotechnology and ...nanomedicine. The thermal dependence of the phosphor's luminescence provides high detection sensitivity and spatial resolution with short acquisition times in, e.g., biological fluids, strong electromagnetic fields, and fast‐moving objects. Here, it is shown that nanoparticles of (Tb0.914Eu0.086)2(PDA)3(H2O)·2H2O (PDA = 1,4‐phenylenediacetic acid), the first lanthanide–organic framework prepared by the spray‐drying method, are excellent nanothermometers operating in the solid state in the 10–325 K range (quantum yield of 0.25 at 370 nm, at room temperature). Intriguingly, this system is the most sensitive cryogenic nanothermometer reported so far, combining high sensitivity (up to 5.96 ± 0.04% K−1 at 25 K), reproducibility (in excess of 99%), and low‐temperature uncertainty (0.02 K at 25 K).
One of the most sensitive cryogenic thermometers (5.96% K−1 at 25 K) reported so far is described, consisting of lanthanide (Tb3+, Eu3+) organic framework nanoparticles prepared by spray‐drying, exhibiting an excellent reproducibility (>99%) and low‐temperature uncertainty (0.02 K at 25 K).
The use of covalent organic frameworks (COFs) in practical applications demands shaping them into macroscopic objects, which remains challenging. Herein, we report a simple three‐step method to ...produce COF aerogels, based on sol‐gel transition, solvent‐exchange, and supercritical CO2 drying, in which 2D imine‐based COF sheets link together to form hierarchical porous structures. The resultant COF aerogel monoliths have extremely low densities (ca. 0.02 g cm−3), high porosity (total porosity values of ca. 99 %), and mechanically behave as elastic materials under a moderate 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: 32 g g−1), with high removal efficiency (ca. 99 %). The same three‐step method can be used to create functional composites of these COF aerogels with nanomaterials.
A three‐step method produces COF aerogel monoliths, based on sol–gel transition, solvent‐exchange, and supercritical CO2 drying. 2D imine‐based COF sheets link together to form hierarchical porous structures. The aerogels have extremely low densities, high porosity, and mechanically behave as elastic or plastic materials under different strain. They show excellent absorption capacity with high removal efficiency.
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