No abstract

Metal–organic frameworks (MOFs) are among the most attractive porous materials available today. They have garnered much attention for their potential utility in many different areas such as gas storage, separation, catalysis, and biomedicine. However, very little is known about the possible health or environmental risks of these materials. Here, the results of toxicity studies on sixteen representative uncoated MOF nanoparticles (nanoMOFs), which were assessed for cytotoxicity to HepG2 and MCF7 cells in vitro, and for toxicity to zebrafish embryos in vivo, are reported. Interestingly, there is a strong correlation between their in vitro toxicity and their in vivo toxicity. NanoMOFs were ranked according to their respective in vivo toxicity (in terms of the amount and severity of phenotypic changes observed in the treated zebrafish embryos), which varied widely. Altogether these results show different levels of toxicity of these materials; however, leaching of solubilized metal ions plays a main role.

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.

Pollution of water with heavy metals is a global environmental problem whose impact is especially severe in developing countries. Among water-purification methods, adsorption of heavy metals has proven to be simple, versatile and cost-effective. However, there is still a need to develop adsorbents with a capacity to remove multiple metal pollutants from the same water sample. Herein we report the complementary adsorption capacities of metal-organic frameworks (MOFs; here, UiO-66 and UiO-66(SH)2) and inorganic nanoparticles (iNPs; here, cerium-oxide NPs) into composite materials. These adsorbents, which are spherical microbeads generated in one step by continuous-flow spray-drying, efficiently and simultaneously remove multiple heavy metals from water, including As(III and V), Cd(II), Cr(III and VI), Cu(II), Pb(II) and Hg(II). We further show that these microbeads can be used as packing material in a prototype of a continuous-flow water treatment system, in which they retain their metal-removal capacities upon regeneration with a gentle acidic treatment. As proof-of-concept, we evaluated these adsorbents for purification of laboratory water samples prepared to independently recapitulate each of two strongly-polluted rivers: the Bone (Indonesia) and Buringanga (Bangladesh) rivers. In both cases, our microbeads reduced the levels of all the metal contaminants to below the corresponding permissible limits established by the World Health Organization (WHO). Moreover, we demonstrated the capacity of these microbeads to lower levels of Cr(VI) in a water sample collected from the Sarno River (Italy). Finally, to create adsorbents that could be magnetically recovered following their use in water purification, we extended our spraydrying technique to simultaneously incorporate two types of iNPs (CeO2 and Fe3O4) into UiO-66(SH)2, obtaining CeO2/Fe3O4@UiO-66-(SH)2 microbeads that adsorb heavy metals and are magnetically responsive.water by a magnet. Given their ready formation and tunability, we are confident that such iNP@MOF-Beads will prove utile in future water-purification applications.

Here, a two-step method is reported that enables imparting new functionalities to covalent organic frameworks (COFs) by nanoparticle confinement. The direct reaction between 1,3,5-tris(4-aminophenyl)benzene and 1,3,5-benzenetricarbaldehyde in the presence of a variety of metallic/metal-oxide nanoparticles resulted in embedding of the nanoparticles in amorphous and non-porous imine-linked polymer organic spheres (NP@a-1). Post-treatment reactions of NP@a-1 with acetic acid under reflux led to crystalline and porous imine-based COF-hybrid spheres (NP@c-1). Interestingly, Au@c-1 and Pd@c-1 were found to be catalytically active.

Hybrid core–shell Au/CeO2 nanoparticles (NPs) dispersed in UiO-66 shaped into microspherical beads are created using the spray-drying continuous-flow method.

Metal-organic frameworks (MOFs) built up from connecting M-XF pillars through N-donor ligands are among the most attractive adsorbents and separating agents for CO and hydrocarbons today. The continuous, one-step spray-drying synthesis of several members of this isoreticular MOF family varying the anionic pillar (XF =[SiF ] and [TiF ] ), the N-donor organic ligand (pyrazine and 4,4'-bipyridine) and the metal ion (M=Co, Cu and Zn) is demonstrated here. This synthetic method allows them to be obtained in the form of spherical superstructures assembled from nanosized crystals. As confirmed by CO and N sorption studies, most of the M-XF -based MOFs synthesised through spray-drying can be considered "ready-to-use" sorbents as they do not need additional purification and time consuming solvent exchange steps to show comparable porosity and sorption properties with the bulk/single-crystal analogues. Stability tests of nanosized M-SiF -based MOFs confirm their low stability in most solvents, including water and DMF, highlighting the importance of protecting them once synthesised. Finally, for the first time it was shown that the spray-drying method can also be used to assemble hydrogen-bonded open networks, as evidenced by the synthesis of MPM-1-TIFSIX.

Herein, we describe an ew class of porous composites comprising metal-organic framework (MOF) crystals confined in single spherical matrices made of packed covalentorganic framework (COF) nanocrystals.T hese MOF@COF composites are synthesized through at wo-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.W er eport that water sorption in these new pores occurs within the same pressure window as in the COF pores.O ur new MOF@COF composites,w ith their additional pores at the MOF/COF interface,s hould have implications for the development of new composites.