Showing papers by "Mohamed Eddaoudi published in 2019"
TL;DR: The real-space observation of structural defects in the catalytic MOF UiO-66 using a combination of low-dose transmission electron microscopy and electron crystallography is reported, enabling their distributions, evolutions during crystallization and effects on the material’s catalytic activity to be explored.
Abstract: Defect engineering of metal-organic frameworks (MOFs) offers promising opportunities for tailoring their properties to specific functions and applications. However, determining the structures of defects in MOFs-either point defects or extended ones-has proved challenging owing to the difficulty of directly probing local structures in these typically fragile crystals. Here we report the real-space observation, with sub-unit-cell resolution, of structural defects in the catalytic MOF UiO-66 using a combination of low-dose transmission electron microscopy and electron crystallography. Ordered 'missing linker' and 'missing cluster' defects were found to coexist. The missing-linker defects, reconstructed three-dimensionally with high precision, were attributed to terminating formate groups. The crystallization of the MOF was found to undergo an Ostwald ripening process, during which the defects also evolve: on prolonged crystallization, only the missing-linker defects remained. These observations were rationalized through density functional theory calculations. Finally, the missing-cluster defects were shown to be more catalytically active than their missing-linker counterparts for the isomerization of glucose to fructose.
312 citations
TL;DR: It is demonstrated that two fluorinated metal–organic frameworks selectively remove SO2 from synthetic flue gas and can sense SO2 with p.p.m..
Abstract: Conventional SO2 scrubbing agents, namely calcium oxide and zeolites, are often used to remove SO2 using a strong or irreversible adsorption-based process. However, adsorbents capable of sensing and selectively capturing this toxic molecule in a reversible manner, with in-depth understanding of structure-property relationships, have been rarely explored. Here we report the selective removal and sensing of SO2 using recently unveiled fluorinated metal-organic frameworks (MOFs). Mixed gas adsorption experiments were performed at low concentrations ranging from 250 p.p.m. to 7% of SO2. Direct mixed gas column breakthrough and/or column desorption experiments revealed an unprecedented SO2 affinity for KAUST-7 (NbOFFIVE-1-Ni) and KAUST-8 (AlFFIVE-1-Ni) MOFs. Furthermore, MOF-coated quartz crystal microbalance transducers were used to develop sensors with the ability to detect SO2 at low concentrations ranging from 25 to 500 p.p.m.
270 citations
TL;DR: A luminescent Zr(IV)-based metal-organic framework, with the underlying fcu topology, encompassing a π-conjugated organic ligand with a thiadiazole functionality, exhibits an unprecedented low detection limit of 66 nM for amines in aqueous solution, driven by hydrogen-bonding interactions between the linker and the hosted amines.
Abstract: A luminescent Zr(IV)-based metal–organic framework (MOF), with the underlying fcu topology, encompassing a π-conjugated organic ligand with a thiadiazole functionality, exhibits an unprecedented low detection limit of 66 nM for amines in aqueous solution. Markedly, this ultralow detection is driven by hydrogen-bonding interactions between the linker and the hosted amines. This observation is supported by density functional theory (DFT) calculations, which clearly corroborate the suppression of the twisting motion of thiadiazole core in the presence of amine, reducing significantly the nonradiative recombination pathways and subsequently enhancing the emission intensity. Credibly, nicotine regarded as a harmful chemical and bearing an amine pending group is also detected with high sensitivity, positioning this MOF as a potential sensor for practical environmental applications. This finding serves also as a benchmark to understand the sensing mechanism in MOFs.
179 citations
142 citations
TL;DR: This work demonstrates an approach to synthesizing and structurally characterizing three atomically precise anion-templated silver thiolate nanoclusters, two of which form one- and two-dimensional structural frameworks composed of bipyridine-linked nanocluster nodes (referred to as Nanocluster-based frameworks, NCFs).
Abstract: Here, we demonstrate an approach to synthesizing and structurally characterizing three atomically precise anion-templated silver thiolate nanoclusters, two of which form one- and two-dimensional st...
114 citations
TL;DR: It is demonstrated that the fabricated hybrid membranes display a high propylene/propane separation performance, far beyond the current trade-off limit of polymer membranes with excellent properties under industrial conditions.
Abstract: Membrane-based separation is poised to reduce the operation cost of propylene/propane separation; however, identifying a suitable molecular sieve for membrane development is still an ongoing challenge. Here, the successful identification and use of a metal-organic framework (MOF) material as fillers, namely, the Zr-fum-fcu-MOF possessing an optimal contracted triangular pore-aperture driving the efficient diffusive separation of propylene from propane in mixed-matrix membranes are reported. It is demonstrated that the fabricated hybrid membranes display a high propylene/propane separation performance, far beyond the current trade-off limit of polymer membranes with excellent properties under industrial conditions. Most importantly, the mechanism behind the exceptional high propylene/propane selectivity is delineated by exploring theoretically the efficiency of sieving of different conformers of propane through the hypothesized triangular rigid pore-aperture of Zr-fum-fcu-MOF.
102 citations
TL;DR: In this paper, a fluorinated MOF with an appropriate pore system was developed to enable the efficient capture of CO2 from flue gas at 298 K. The MOF, dptz-CuTiF6, exhibits excellent volumetric and gravimetric CO2 uptakes at 10% CO2 and 298 K, which are superior to those of the reference aqueous amine technique, with significantly lower energy input for regeneration (38kJ mol−1 versus 105kJmol−1).
100 citations
TL;DR: The ensemble of polyoxometalates and cyclodextrins as molecular building blocks asMBBs has yielded two unprecedented POM-CD-MOFs, namely [PW12O40]3- and α-CD MOF (POT-CD) as well as [P10Pd15.5O50]19- and γ-CDMOF (pOP-CD), with distinct properties not shared by their isolated parent MBBs.
Abstract: Self-assembly allows structures to organize themselves into regular patterns by using local forces to find the lowest-energy configuration. However, assembling organic and inorganic building blocks in an ordered framework remains challenging due to difficulties in rationally interfacing two dissimilar materials. Herein, the ensemble of polyoxometalates (POMs) and cyclodextrins (CDs) as molecular building blocks (MBBs) has yielded two unprecedented POM-CD-MOFs, namely [PW12O40]3– and α-CD MOF (POT-CD) as well as [P10Pd15.5O50]19– and γ-CD MOF (POP-CD), with distinct properties not shared by their isolated parent MBBs. Markedly, the POT-CD features a nontraditional enhanced Li storage behavior by virtue of a unique “amorphization and pulverization” process. This opens the door to a new generation of hybrid materials with tuned structures and customized functionalities.
91 citations
TL;DR: This study demonstrates that high- quality 2D MOF sheets and thin films are enabled by 2D MXene precursors, and believes that the high-quality MOF films prepared in this study pave the way for many device applications.
Abstract: Synthesis of nanoscale metal-organic frameworks (MOFs) is a highly challenging task because conventional soluble metal salt precursors are not easy to manipulate spatially, thus normally leading to bulk MOFs. In the present work, V2CTx MXene is demonstrated for the first time as a metal precursor to fabricate two-dimensional (2D) MOF nanosheets, whose thickness (6 to 18 nm) can be tuned by varying the reaction temperature. The highly electronegative surface atoms of MXene and sufficient accessible attacking sites for ligands are responsible for the evolution of 2D MOF nanosheets. Moreover, highly oriented and smooth MOF thin films have been grown based on these nanosheets using a convenient spin coating process. With the impregnation of nonvolatile H3PO4, the MOF thin film exhibits a proton-conducting property. This study demonstrates that high-quality 2D MOF sheets and thin films are enabled by 2D MXene precursors. We believe that the high-quality MOF films prepared in this study pave the way for many device applications.
78 citations
TL;DR: In this paper, the reticular chemistry approach was implemented on a very stable ultra-microporous fluorinated MFFIVE-1-Ni MOFs to unveil the effect of subtle changes of the structure-employment of different fluorinated inorganic block on the adsorption of C2H2, C 2H4 and CO2.
63 citations
TL;DR: The systematic generation of the highly-connected minimal edge-transitive related nets from parent edge- transitive nets is reported, and their use as a guide for the deliberate design and directional assembly of high-ly-coordinated MOFs from their associated net-coded building units (net-cBUs), 12-connected double six-membered ring (d6R) building units.
Abstract: Minimal edge-transitive nets are regarded as suitable blueprints for the successful practice of reticular chemistry, and par excellence ideal for the deliberate design and rational construction of ...
TL;DR: The deliberate construction and performance assessment of extremely sensitive sensors using an interdigitated electrode (IDE)-based capacitor and a quartz crystal microbalance (QCM) as transducing substrates are reported, allowing for concurrent detection of uncomfortable humidity levels and CO2 concentration in confined spaces.
Abstract: Conventional materials for gas/vapor sensing are limited to a single probe detection ability for specific analytes. However, materials capable of concurrent detection of two different probes in their respective harmful levels and using two types of sensing modes have yet to be explored. In particular, the concurrent detection of uncomfortable humidity levels and CO2 concentration (400–5000 ppm) in confined spaces is of extreme importance in a great variety of fields, such as submarine technology, aerospace, mining, and rescue operations. Herein, we report the deliberate construction and performance assessment of extremely sensitive sensors using an interdigitated electrode (IDE)-based capacitor and a quartz crystal microbalance (QCM) as transducing substrates. The unveiled sensors are able to simultaneously detect CO2 within the 400–5000 ppm range and relative humidity levels below 40 and above 60%, using two fluorinated metal–organic frameworks, namely, NbOFFIVE-1-Ni and AlFFIVE-1-Ni, fabricated as a thi...
TL;DR: In this paper, the molecular-building-block strategy was used to isolate three porous organic polymers (POPs) with high surface areas (i.e., 5,120 and 5,730 m2 g−1) and display outstanding gravimetric methane storage properties.
TL;DR: In this article, the separation of fluid SF6/N2 mixtures using the recently synthesized metal-organic framework SIFSIX-2-Cu and its interpenetrated polymorph SIFSE-6 2-Cu-i has been systematically studied by employing Monte Carlo and Molecular Dynamics simulations.
TL;DR: In this paper, the adsorption of water in the recently synthesized rare earth-based Y-shp-MOF-5 metal-organic framework was explored by combining density functional theory calculations and force-field-based Monte-Carlo simulations.
Abstract: The adsorption of water in the recently synthesized rare-earth-based Y-shp-MOF-5 metal–organic framework was explored by combining density functional theory calculations and force-field-based Monte...
TL;DR: Water adsorption/desorption isotherms of Cr-soc-MOF-1 were monitored electrically, and molecular modelling established the relationship between the evolutive water-hydrogen bonded network and the "electrical" isotherm for this water-mediated proton conducting MOF.
TL;DR: In this article, the radiative and nonradiative decay channels of BTDB can be interplayed and precisely controlled through concentration and hydrogen-bond interactions as directly evidenced experimentally and theoretically.
Abstract: Benzothiadiazole dibenzoic acid (BTDB) derivative is a well-known organic linker in various metal–organic framework structures as well as a fluorescent probe in biological systems. Here, we demonstrate that the radiative and nonradiative decay channels of BTDB can be interplayed and precisely controlled through concentration and hydrogen-bond interactions as directly evidenced experimentally and theoretically. This leads to excited-state structural changes that significantly suppress the torsional motion around the benzothiadiazole moiety, leading to an enormous increase in the emission quantum yields from ∼1 to 70%. These changes are associated with the existence of two equilibria, where dimers and small oligomers form in dimethylformamide (DMF), with high formation constants of 18 000 M–1 and 1.2 × 1013 M–3, respectively. These evolving species, i.e., the dimers and oligomers, are formed via hydrogen bonds between carboxylic acid groups present at the far edge of the rodlike BTDB molecules. The estimate...
TL;DR: This study provides great potential for isoporous block copolymer membranes as a delivery platform for a wide variety of biomedical applications.
TL;DR: These porphyrin-based MOF thin films were shown to function effectively as donor layers in solar cells based on a Fullerene-C60 acceptor and the metallation of the ligand was found to be effective to tune the MOF bandgap.
Abstract: This study reports on the optoelectronic properties of porphyrin-based metal–organic framework (MOF) thin films fabricated by a facile liquid-phase epitaxy approach. This approach affords the growth of MOF thin films that are free of morphological imperfections, more suitable for optoelectronic applications. Chemical modifications such as the porphyrin ligand metallation have been found to preserve the morphology of the grown films making this approach particularly suitable for molecular alteration of MOF thin film optoelectronic properties without compromising its mesoscale morphology significantly. Particularly, the metallation of the ligand was found to be effective to tune the MOF bandgap. These porphyrin-based MOF thin films were shown to function effectively as donor layers in solar cells based on a Fullerene-C60 acceptor. The ability to fabricate MOF solar cells free of a liquid-phase acceptor greatly simplifies device fabrication and enables pairing of MOFs as light absorbers with a wide range of acceptors including non-fullerene acceptors.
01 Nov 2019
TL;DR: In the version of this article originally published, the name of author Gongping Liu was mistakenly written with the names in reverse order as mentioned in this paper, which has now been corrected by the author.
Abstract: In the version of this Article originally published, the name of author Gongping Liu was mistakenly written with the names in reverse order. This has now been corrected.
TL;DR: In the version of this Article originally published, the units of the y axis of Fig. 3b were incorrectly given as ‘106 cm2 s–1’; this has been corrected in the online versions of the Article.
Abstract: In the version of this Article originally published, the units of the y axis of Fig. 3b were incorrectly given as ‘106 cm2 s–1’; they should have been ‘10–8 cm2 s–1’. This has been corrected in the online versions of the Article.
Patent•
29 Apr 2019
TL;DR: A molecular building block composition can include a metal ion component; and a ligand component including a core including at least one functional group associated with the metal ion and the core.
Abstract: A molecular building block composition can include a metal ion component; and a ligand component including a core including at least one functional group associated with the metal ion component and the core.