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The SARS-CoV-2 (COVID-19) pandemic outbreak led to enormous social and economic repercussions worldwide, felt even to this date, making the design of new therapies to combat fast-spreading viruses an imperative task. In the face of this, diverse cutting-edge nanotechnologies have risen as promising tools to treat infectious diseases such as COVID-19, as well as challenging illnesses such as cancer and diabetes. Aside from these applications, nanoscale metal-organic frameworks (nanoMOFs) have attracted much attention as novel efficient drug delivery systems for diverse pathologies. However, their potential as anti-COVID-19 therapeutic agents has not been investigated. Herein, we propose a pioneering anti-COVID MOF approach by studying their potential as safe and intrinsically antiviral agents through screening various nanoMOF. The iron(III)-trimesate MIL-100 showed a noteworthy antiviral effect against SARS-CoV-2 at the micromolar range, ensuring a high biocompatibility profile (90% of viability) in a real infected human cellular scenario. This research effectively paves the way toward novel antiviral therapies based on nanoMOFs, not only against SARS-CoV-2 but also against other challenging infectious and/or pulmonary diseases.

Pharmaceutical active compounds (PhACs) are some of the most recalcitrant water pollutants causing undesired environmental and human effects. In absence of adapted decontamination technologies, there is an urgent need to develop efficient and sustainable alternatives for water remediation. Metal-organic frameworks (MOFs) have recently emerged as promising candidates for adsorbing contaminants as well as providing photoactive sites, as they possess exceptional porosity and chemical versatility. To date, the reported studies using MOFs in water remediation have been mainly focused on the removal of a single type of PhACs and rarely on the combined elimination of PhACs mixtures. Herein, the eco-friendly bismuth-based MOF, SU-101, has been originally proposed as an efficient adsorbent-photocatalyst for the elimination of a mixture of three challenging persistent PhACs, frequently detected in wastewater and surface water in ng L -1 to mg·L -1 concentrations: the antibiotic sulfamethazine (SMT), the anti-inflammatory diclofenac (DCF), and the antihypertensive atenolol (At). Adsorption experiments of the mixture revealed that SU-101 exhibited a great adsorption capacity towards At, resulting in an almost complete removal (94.1 ± 0.8% for combined adsorption) in only 5 h. Also, SU-101 demonstrated a remarkable photocatalytic activity under visible light to simultaneously degrade DCF and SMT (99.6 ± 0.4% and 89.2 ± 1.4%, respectively). In addition, MOF-contaminant interactions, the photocatalytic mechanism and degradation pathways were investigated, also assessing the toxicity of the resulting degradation products. Even further, recycling and regeneration studies were performed, demonstrating its efficient reuse for 4 consecutive cycles without further treatment, and its subsequent successful regeneration by simply washing the material with a NaCl solution., (© 2024. The Author(s).)

The effect of solvent has been investigated for the synthesis of bismuth gallate compounds, of which the water-based bismuth subgallate has been used as an active pharmaceutical ingredient (API) for over a century. Using methanol as a solvent, two new bismuth gallates were acquired: first a flexible 3-periodic metal-organic framework (MOF) forms, which transforms upon extended synthesis times into a layered 2-periodic coordination polymer of the same bismuth-to-gallate ratio. The structures were determined by three-dimensional electron diffraction. Synthesis in ethanol resulted in the formation of the MOF phase, but not the layered phase. The layered material of the methanol-based synthesis was used as a Lewis acid catalyst due to its higher stability, showing a comparatively quick and regiospecific conversion of styrene oxide to 2-methoxy-2-phenylethanol, indicating the presence of open metal sites in the material. The acquisition of bismuth gallate structures of varying periodicity highlights the prospect of acquiring novel MOFs and coordination polymers from the same components of APIs.

Electron transport through metal-organic frameworks by a hopping mechanism between discrete redox active sites is coupled to diffusion-migration of charge-balancing counter cations. Experimentally determined apparent diffusion coefficients, D e for charge migration through a PIZOF-type MOF, Zr(dcphOH-NDI) that is composed of redox-active naphthalenediimide (NDI) linkers, spans over 2 orders of magnitude. More importantly, however, the microscopic mechanisms for cation-coupled electron propagation are contingent on differing factors depending on the size of the cation and its propensity to engage in ion pairs with reduced linkers, either non-specifically or in defined structural arrangements. Based on computations and in agreement with experimental results, we show that ion pairing generally has an adverse effect on cation transport, thereby slowing down charge transport. In Zr(dcphOH-NDI), however, specific cation-linker interactions can open pathways for concerted cation-coupled electron transfer processes that can outcompete limitations from reduced cation flux.app , that characterize this form of charge transport thus contain contributions from both processes. While this is well established for MOFs, microscopic descriptions of this process are largely lacking. Herein, we systematically lay out different scenarios for cation-coupled electron transfer processes that are at the heart of charge diffusion through MOFs. Through systematic variations of solvents and electrolyte cations, it is shown that the D e app for charge migration through a PIZOF-type MOF, Zr(dcphOH-NDI) that is composed of redox-active naphthalenediimide (NDI) linkers, spans over 2 orders of magnitude. More importantly, however, the microscopic mechanisms for cation-coupled electron propagation are contingent on differing factors depending on the size of the cation and its propensity to engage in ion pairs with reduced linkers, either non-specifically or in defined structural arrangements. Based on computations and in agreement with experimental results, we show that ion pairing generally has an adverse effect on cation transport, thereby slowing down charge transport. In Zr(dcphOH-NDI), however, specific cation-linker interactions can open pathways for concerted cation-coupled electron transfer processes that can outcompete limitations from reduced cation flux.

The first bioinspired microporous metal-organic framework (MOF) synthesized using ellagic acid, a common natural antioxidant and polyphenol building unit, is presented. Bi 2 O(H 2 O) 2 (C 14 H 2 O 8 )· n H 2 O (SU-101) was inspired by bismuth phenolate metallodrugs, and could be synthesized entirely from nonhazardous or edible reagents under ambient aqueous conditions, enabling simple scale-up. Reagent-grade and affordable dietary supplement-grade ellagic acid was sourced from tree bark and pomegranate hulls, respectively. Biocompatibility and colloidal stability were confirmed by in vitro assays. The material exhibits remarkable chemical stability for a bioinspired MOF (pH = 2-14, hydrothermal conditions, heated organic solvents, biological media, SO 2 and H 2 S), attributed to the strongly chelating phenolates. A total H 2 S uptake of 15.95 mmol g -1 was recorded, representing one of the highest H 2 S capacities for a MOF, where polysulfides are formed inside the pores of the material. Phenolic phytochemicals remain largely unexplored as linkers for MOF synthesis, opening new avenues to design stable, eco-friendly, scalable, and low-cost MOFs for diverse applications, including drug delivery.

The effect of solvent has been investigated for the synthesis of bismuth gallate compounds, of which the water-based bismuth subgallate has been used as an active pharmaceutical ingredient (API) for over a century. Using methanol as a solvent, two new bismuth gallates were acquired: first a flexible 3-periodic metal–organic framework (MOF) forms, which transforms upon extended synthesis times into a layered 2-periodic coordination polymer of the same bismuth-to-gallate ratio. The structures were determined by three-dimensional electron diffraction. Synthesis in ethanol resulted in the formation of the MOF phase, but not the layered phase. The layered material of the methanol-based synthesis was used as a Lewis acid catalyst due to its higher stability, showing a comparatively quick and regiospecific conversion of styrene oxide to 2-methoxy-2-phenylethanol, indicating the presence of open metal sites in the material. The acquisition of bismuth gallate structures of varying periodicity highlights the prospect of acquiring novel MOFs and coordination polymers from the same components of APIs. [ABSTRACT FROM AUTHOR]

Single‐crystal electron diffraction has shown to be powerful for structure determination of nano‐ and submicron‐sized crystals that are too small to be studied by single‐crystal X‐ray diffraction. However, it has been very challenging to obtain high quality electron diffraction data from beam sensitive crystals such as metal–organic frameworks (MOFs). It is even more difficult to locate guest species in the pores of MOF crystals. Here, we present synthesis of a novel porous cobalt MOF with 1D channels, [Co2(Ni‐H4TPPP)]⋅2 DABCO⋅6 H2O, (denoted Co‐CAU‐36; DABCO=1,4‐diazabicyclo[2.2.2]octane), and its structure determination using continuous rotation electron diffraction (cRED) data. By combining a fast hybrid electron detector with low sample temperature (96 K), high resolution (0.83–1.00 Å) cRED data could be obtained from eight Co‐CAU‐36 crystals. Independent structure determinations were conducted using each of the eight cRED datasets. We show that all atoms in the MOF framework could be located. More importantly, we demonstrate for the first time that organic molecules in the pores, which were previously difficult to find, could be located using the cRED data. A comparison of eight independent structure determinations using different datasets shows that structural models differ only on average by 0.03(2) Å for the framework atoms and 0.10(6) and 0.16(12) Å for DABCO and water molecules, respectively. Continuous‐rotation electron diffraction (cRED) was used as a stand‐alone method for both structure solution and refinement of submicron‐sized crystals of a novel cobalt metal–organic framework. We show that the method is robust; not only the framework structure, but also solvent molecules in the pores could be precisely located. [ABSTRACT FROM AUTHOR]

Abstract: Herein, we report a versatile carbonylation protocol using heterogeneous Pd0 nanoparticles supported on the metal–organic frameworks (MOFs) MIL‐88B‐NH2 (Fe/Cr). The synthesis of a vast array of carbonyls, which includes amides, esters, carboxylic acids, and α‐ketoamides, was achieved through mono‐ and dicarbonylation reactions. The selectivity could be controlled simply by tuning the reaction conditions. Superior activity and selectivity were recorded in some cases compared to that achieved with commercial Pd/C. However, the utility of an elaborate catalyst support is questionable and important reactivity and recyclability issues are discussed. [ABSTRACT FROM AUTHOR]

Three new In-MOFs with –NH2 and/or –NO2 functionalities are reported using 2-amino- (H2BDC-NH2), 2-nitro- (H2BDC-NO2) and 2-amino-5-nitroterephthalic acid (H2BDC-NH2/NO2). Their structures were determined from single crystal X-ray diffraction data. The structure of the first In-MOF of composition [In(BDC-NH3)(BDC-NH2)]·1.6DMF·1.9H2O (In-BDC-NH2; DMF is dimethylformamide; the space group is P6222, a = b = 14.738(2) Å and c = 12.257(3) Å) is built up by two interpenetrating nets of InO8 polyhedra interconnected by BDC-NH22− ions to form a framework with qtz topology. Charge balance is accomplished by partial protonation of the amino group, which was confirmed by IR spectroscopy. The interpenetration leads to a decrease of the pore dimension (4.4 Å in diameter). Thermogravimetric analysis revealed stability up to 300 °C. Replacement of H2BDC-NH2 by H2BDC-NO2 in the reaction mixture led to the isoreticular MOF containing no –NO2 groups but exclusively un- and amino-functionalized linkers. Hence an indium mediated reduction of the H2BDC-NO2 linker molecule during solvothermal synthesis has occurred. The use of H2BDC-NH2/NO2 under exactly the same reaction conditions did not result in the formation of a MOF, but by changing the synthesis parameters, a new –NH2/–NO2 bifunctionalised In-MOF of composition (DMA)2[In3(μ3-O)(BDC-NH2/NO2)4.5]·DMF (DMA is dimethylammonium), denoted In-BDC-NH2/NO2, was obtained. The crystal morphology can be altered from cubic to truncated octahedral crystals by varying the DMF/ethanol volume ratio during synthesis. The compound crystallises in the cubic space group I4̅3m, a = 24.8947(1) Å, and the framework contains trinuclear {In3(μ3-O)} clusters which are interlinked by the BDC-NH2/NO22− ions to form super-tetrahedra. Four face-sharing super-tetrahedra form ultra-tetrahedra which are connected to form the final cubic framework with an ncb topology and isolated inaccessible pores. [ABSTRACT FROM AUTHOR]

A bismuth-based metal-organic framework (MOF), [Bi(BTC)(H2O)]·2H2O·MeOH denoted CAU-17, was synthesized and found to have an exceptionally complicated structure with helical Bi-O rods cross-linked by 1,3,5-benzenetricarboxylate (BTC3-) ligands. Five crystallographically independent 1D channels including two hexagonal channels, two rectangular channels, and one triangular channel have accessible diameters of 9.6, 9.6, 3.6, 3.6, and 3.4 Å, respectively. The structure is further complicated by twinning. Rod-incorporated MOF structures typically have underlying nets with only one unique node and three or four unique edges. In contrast, topological analysis of CAU-17 revealed unprecedented complexity for a MOF structure with 54 unique nodes and 135 edges. The complexity originates from the rod packing and the rods themselves, which are related to aperiodic helices. [ABSTRACT FROM AUTHOR]

The systematic investigation of the solvothermal system Al 3+ /5-fluoroisophthalic acid (H 2 m BDC-5F)/isophthalic acid (H 2 m BDC)/DMF/H 2 O through a mixed-linker approach led to new mixed-linker CAU-10 derivatives containing 11, 28 and 44% of fluorinated linker molecules (denoted as CAU-10-H/F 11 , CAU-10-H/F 28 and CAU-10-H/F 44 , respectively), as determined by NMR spectroscopy. The crystal structure of CAU-10-H/F 28 was determined using the Rietveld method (space group I 4 1 md , a = b = 21.3075(5), c = 10.7101(3) Å). The structure is built up by helical chains composed of cis corner-sharing AlO 6 polyhedra. Each of these helices is interconnected to four adjacent helices with alternating rotational orientation through the carboxylate groups of m BDC 2- linker molecules. Thus, accessible, square-shaped channels are formed. Sorption measurements revealed a high dependency of the adsorbed amount of gas on the degree of fluorination. With increasing fluorination, the total uptake decreases in N 2 , H 2 and H 2 O sorption experiments and the hydrophobic character of the pores increases. In addition, an extended CAU-10 derivative, CAU-10-HTATB, was discovered using the tricarboxylic acid 4,4′,4″- s -triazine-2,4,6-triyl-tribenzoic acid (H 3 TATB) during the high-throughput investigation of the system Al 3+ /H 3 TATB/DMF/H 2 O. This new MOF, which was denoted CAU-10-HTATB, was thoroughly characterized using IR spectroscopy, thermogravimetric and elemental analysis, temperature dependent powder X-ray diffraction (PXRD) and sorption measurements. Although the compound is thermally stable up to 400 °C according to temperature-dependent PXRD measurements, it is not porous towards N 2 molecules. The structure of CAU-10-HTATB could be also refined from PXRD data using the Rietveld method (space group I 4 1 / a , a = b = 36.438 (1), c = 10.9373 (9) Å). [ABSTRACT FROM AUTHOR]

A new sulfone-functionalized metal-organic framework [Al(OH)(SDBA)]·0.25DMF, denoted CAU-11, was synthesized using a V-shaped linker molecule 4,4'-sulfonyldibenzoic acid (H2SDBA). The crystal structure was solved from synchrotron X-ray powder diffraction data. Chains of trans corner-sharing AlO6 octahedra are interconnected by the carboxylate groups to form layers (ABAB stacking). Within the layers, hydrophobic lozenge-shaped pores with a diameter of 6.4 × 7.1 Ų are present inducing permanent porosity (aBET = 350 m² g-1 and Vmicro = 0.17 cm³ g-1). With the application of HT-methods (HT = high throughput), the isoreticular carboxylate functionalized compound [Al(OH)(H2DPSTC)]·0.5H2O (CAU-11-COOH) was synthesized using the linker molecule 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride (DPSDA), which hydrolyzes under the reaction conditions. Due to the additional noncoordinating carboxylic acid groups the pores are hydrophilic. Changing the molar ratio of Al3+ to linker lead to the discovery of a second new compound [Al2(OH)2(DPSTC)(H2O)2]·0.5H2O (CAU-12). In CAU-12 the linker molecule is fully deprotonated which leads to different connectivity compared to the structure of CAU-11-COOH. Thermal activation of CAU-12 leads to dehydration and transformation of the structure to [Al2(OH)2(DPSTC)]·nH2O (CAU-12-dehy). Coordinated water molecules were removed, and the coordination site is replaced by the previously noncoordinating O atom of the adjacent carboxylate group. The SO2-groups point into the pores resulting in a highly hydrophobic three-dimensional framework. The compounds exhibit high thermal stability in air at least up to 420 °C. Synthesis of CAU-11 can be easily scaled up in very high yields (98%). [ABSTRACT FROM AUTHOR]

• Development of three-dimensional electron diffraction (3DED) methods. • Ab initio structure determination of MOFs and COFs using 3DED. • Reveal of structure–property relationships using 3DED. • Accuracy of 3DED methods on structure determination. Metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) have emerged as the most widely investigated classes of porous materials during the past two decades. The almost unlimited combination of building units (metal clusters and organic molecules) endows highly tuneable porosities and functionalities that are appealing for a wide scope of applications. The applications of MOFs and COFs depend on their physical and chemical properties, which in turn are determined by the arrangement of atoms – the crystal structures. Therefore, structure determination is arguably the most important characterization step for MOFs and COFs. While single crystal X-ray diffraction (SCXRD) is the most widely used method for structure determination, many MOFs and COFs are synthesized in too small sizes or their crystal qualities are too low for SCXRD. During recent years, three-dimensional electron diffraction (3DED) methods has undergone rapid developments and can be used for structure determination of nano- and submicro-sized crystals to overcome this fundamental drawback. In this review, we summarize the development of 3DED methods and their applications for structure elucidation of MOFs and COFs. Advances of 3DED data collection techniques are described, from step-wise rotation to continuous rotation of the crystal. The latter allows fast data collection which is crucial for beam sensitive materials including MOFs and COFs. Examples of ab initio structure determination of various MOFs and COFs by using 3DED are presented, with highlighted examples for solving the structures of mesoporous MOFs, mixed-metal MOFs, flexible MOFs, and for studying host–guest interactions. Finally, the accuracy and reproducibility of structure determination by 3DED are presented. We show the structure information obtained from 3DED provides crucial insights into structure–property relationships, which could further accelerate the development of new functional materials. [ABSTRACT FROM AUTHOR]