![Maximum recovery (after 6 h.) of both inorganic [Hg(II), Pb(II), Tl(I), Cu(II), Ni(II), Ca(II), Mg(II), K(I), Na(I)] and organic contaminants (PY, AO, BG and MB) by MTV-MOF 2 (data collected in Tables S5 and S6).](https://www.researchgate.net/profile/Emilio-Pardo/publication/335071544/figure/fig3/AS:870085275164676@1584455903966/Maximum-recovery-after-6-h-of-both-inorganic-HgII-PbII-TlI-CuII-NiII_Q320.jpg)
![Details of host-guest interactions in (MB)·HgCl2@2. Spot of H-bonds involving serine residue hydroxyl groups anchoring nitrogen atoms of Methylene Blue moieties [N···O distance 3.10 Å] (red dotted lines). Copper and calcium are represented by green and blue spheres respectively, whereas the ligands and guest molecules are depicted as grey and skyblue sticks for carbon and nitrogen respectively. Mercury(II) and chlorine atoms are depicted as magenta and green](https://www.researchgate.net/profile/Emilio-Pardo/publication/335071544/figure/fig5/AS:870085279375365@1584455904118/Details-of-host-guest-interactions-in-MBHgCl22-Spot-of-H-bonds-involving-serine_Q320.jpg)
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Multivariate Metal−Organic Frameworks for the Simultaneous Capture of Organic and Inorganic Contaminants from Water
Abstract and Figures
We report a new water-stable multivariate (MTV) Metal-Organic Framework (MOF) prepared by combining two different oxamide-based metalloligands derived from the natural amino acids L-serine and L-methionine. This unique material features hexagonal channels decorated with two types of flexible and functional “arms” (–CH2OH and –CH2CH2SCH3) capa-ble to act, synergistically, for the simultaneous and efficient removal of both inorganic (heavy metals like Hg2+, Pb2+ and Tl+) and organic (dyes such as Pyronin Y, Auramine O, Brilliant Green and Methylene Blue) contaminants and, in addi-tion, this MTV-MOF is completely reusable. Single-crystal X-ray diffraction (SCXRD) measurements allowed to solve the crystal structure of a host-guest adsorbate, containing both HgCl2 and Methylene Blue, and offered unprecedented snap-shots about this unique dual capture process. This is the very first time that a MOF can be used for the removal of all sorts of pollutants from water resources, thus opening new perspectives for this emerging type of MTV-MOFs.
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... V. Singh et al. Organic contaminants represent more prominent family as compared to inorganic contaminants, which include detergents, dyes, oil/greases, pharmaceutical waste, fertilizers, pesticides, personal care products, plastics, hormones, pesticides, fertilizers, fragrances, poly aromatics, etc. [27]. ...
The current scenario of aquatic resources shows the potential of pollution originating from the ceaseless draining of industrial effluents. The infected waters have raised several human health and environmental risks, encouraging an appropriate opportunity to solve the implications. Conventional approaches utilized for purifying water are time-consuming, inefficient, and expensive. These shortcomings demand the perpetual method of decontaminating colored effluents. Furthermore, metal–organic frameworks (MOFs) are conspicuous nanoporous materials due to their versatile properties and emerged as a better solution for the decontamination of aromatic dyes. MOF-based photo catalysis eliminates organic dyes due to the generation of powerful oxidants under light irradiation. These oxidants mineralize dye effluent to liberate CO and HO molecules as a final product without producing secondary pollution. MOFs incorporated by employing transition metals like Iron, Cobalt, Nickel, Copper, and Zinc are a widely focused group of coordination polymers that exhibit appreciable degradation efficiency toward dyes. The present article comprises a discussion of various waste water treatment methods including various physical, chemical, and biological techniques for the degradation of pollutants in the prior, including their benefits and drawbacks, followed by an overview of nano-MOFs and their features (such as morphology, thermal, chemical, light harvesting ability as well as their water stability) which highlight the use of MOFs as a photocatalyst. A comprehensive study of the photocatalytic potential of MOFs based on Iron, Cobalt, Nickel, Copper, and Zinc has been elaborated along with the current advancements followed by opportunities, current obstacles, and future prospects. The recent development in the photocatalytic efficiency of MOF by doping with metal semiconductors, doping with metal-free semiconductors, doping with a noble metal, and MOF composite are summarized. This review would be helpful for researchers of any stage and also an inspiration for future research on the photocatalytic decontamination of organic waste via MOF-based composites.
... Mixed-metals/linker or multicomponent MOFs could make the difference in terms of light harvesting, exciton generation, and hole and electron separation and transport. For instance, the compositional and structural variances within MTV-MOFs have already led to synergistic functions outperforming the efficiency of singly functionalized MOF variants for gas adsorption, [297] drug release, and even for photocatalysis purposes, including a few works which have been published exploring their potentials for chromium photoreduction. ...
Hexavalent chromium (Cr(VI)) is a highly mobile cancerogenic and teratogenic heavy metal ion. Among the varied technologies applied today to address chromium water pollution, photocatalysis offers a rapid reduction of Cr(VI) to the less toxic Cr(III). In contrast to classic photocatalysts, Metal-Organic frameworks (MOFs) are porous semiconductors that can couple the Cr(VI) to Cr(III) photoreduction to the chromium species immobilization. In this minireview, we wish to discuss and analyze the state-of-the-art of MOFs for Cr(VI) detoxification and contextualizing it to the most recent advances and strategies of MOFs for photocatalysis purposes. The minireview has been structured in three sections: (i) a detailed discussion of the specific experimental techniques employed to characterize MOF photocatalysts, (ii) a description and identification of the key characteristics of MOFs for Cr(VI) photoreduction, and (iii) an outlook and perspective section in order to identify future trends.
Metal-organic frameworks (MOFs), a distinctive funtionalmaterials which is constructed by various metal ions and organic molecules, have gradually attracted researchers' attention from they were founded. In the last decade, MOFs emerge as a biomedical material with potential applications due to their unique properties. However, the MOFs performed as nanocarriers for functional nucleic acid delivery in biomedical applications rarely summarized. In this review, we introduce recent developments of MOFs for nucleic acid delivery in various biologically relevant applications, with special emphasis on cancer therapy (including siRNA, ASO, DNAzyme, miRNA and CpG oligodeoxynucleotides), bioimaging, biosensors and separation of biomolecules. We expect the accomplishment of this review could benefit certain researchers in biomedical field to develop novel sophisticated nanocarriers for functional nucleic acid delivery based on the promising material of MOFs.
The uniqueness of multivariate metal-organic frameworks (MTV-MOFs) has been widely explored to discover their unknown opportunities. While mesoscopic apportionments have been studied, macroscopic heterogeneity and its spatial effects remain unexplored in MTV-MOFs. In this study, we investigated the effect of macroscopic heterogeneity on MTV-MOFs on their uptake behaviors by comparing three types of MTV-MOFs having the functional groups in inner, outer, or entire parts of crystals. Their adsorption behavior for carbon dioxide (CO2) and water (H2O) brought out that functional groups located in the outer part of the crystals dominantly influence the sorption behavior of MTV-MOFs. These results are also visualized by observing iodine adsorption in the three types of MTV-MOFs using scanning transmission electron microscopy-electron energy loss spectroscopy. We believe that this finding provides new ways to decipher and design MTV-MOFs for their unusual properties.
Metal-organic nanotubes (MONTs) are 1-dimensional crystalline porous materials that are formed from ligands and metals in a manner identical to more typical 3-dimensional metal-organic frameworks (MOFs). MONTs form anisotropically in one dimension making them excellent candidates for linker engineering for control of chemical composition and spacing. A novel series of MONTs was synthesized utilizing a mixture of 1,2,4-ditriazole ligands containing both a fully protonated aryl moiety and its tetrafluorinated analog in ratios of, 0 : 1, 1 : 4, 1 : 1, 4 : 1, and 1 : 0, respectively. All MONTs were characterized by both bulk and nanoscale measurements, including SCXRD, PXRD, ssNMR and TEM, to determine the resulting co-polymer architecture (alternating, block, or statistical) and the ligand ratios in the solid materials. All characterization methods point towards statistical copolymerization of the materials in a manner analogous to 3D MOFs, all of which notably could be achieved without destructive analytical methods.
Contamination of aquatic environments by pharmaceuticals used by modern societies has become a serious threat to human beings. Among them, antibiotics are of particular concern due to the risk of creating drug-resistant bacteria and, thus, developing efficient protocols for the capture of this particular type of drug is mandatory. Herein, we report a family of three isoreticular MOFs, derived from natural amino acids, that exhibit high efficiency in the removal of a mixture of four distinct families of antibiotics, such as fluoroquinolones, penicillins, lincomycins, and cephalosporins, as solid-phase extraction (SPE) sorbents. In particular, a multivariate (MTV)-MOF, prepared using equal percentages of amino acids l-serine and l-methionine, also exhibits outstanding recyclability, surpassing the benchmark material activated carbon. The good removal performance of the MTV-MOF was rationalized by means of single-crystal X-ray diffraction. These results highlight the situation of MOFs as a real and promising alternative for the capture of antibiotics from environmental matrices, especially wastewater streams.
A novel water-stable CdII-based metal-organic framework, namely {[Cd(BIBT)(TDC)]·2H2O}n (JXUST-28, BIBT = 4,7-bi(1H-imidazol-1-yl)benzo-[2,1,3]thiadiazole and H2TDC = 2,5-thiophenedicarboxylic acid), was synthesized using a mixed-ligand strategy. Structural analysis demonstrates that JXUST-28 exhibits a two-dimensional layer structure with 4-connected sql topology. Intriguingly, JXUST-28 presents good stability in boiling water (at least 5 days), common organic solvents and aqueous solutions with different pH values of 2-12 (more than 24 hours). Furthermore, fluorescence experiments revealed that JXUST-28 could sense Hg2+ ions in aqueous solution via a quenching effect with a detection limit of 0.097 μM. Meanwhile, JXUST-28 can also be regenerated at least 5 times to detect Hg2+ ions. In addition, light-emitting diode lamps, luminescent films, and test papers of JXUST-28 have been successfully developed for practical applications.
Due to the rapid industrialization across the world, various environmental pollutants have begun to accumulate in water, air and soil. This endangers the ecological environment of the earth, and environmental remediation has become an immediate concern. Among various environmental remediation techniques, piezo‐catalytic techniques uniquely take advantage of piezoelectric effect, has attracted much attention. Piezoelectric effects allow for pollutant degradation directly, while also enhancing photocatalysis by reducing photogenerated carriers recombination. In this review, we provide a comprehensive summary of recent developments of piezo‐catalytic techniques for environmental remediation. The foundation of piezoelectric effect, classification of piezoelectric materials and its application in environmental remediation are systematically summarized. We also analyze the potential underlying mechanisms. Finally, the urgent problems and prospects of piezo‐catalytic techniques are discussed.
Crystal engineering of metal-organic frameworks (MOFs) has allowed the construction of complex structures at atomic precision, but has yet to reach the same level of sophistication as organic synthesis. The synthesis of complex MOFs with multiple organic and/or inorganic components is ultimately limited by the lack of control over framework assembly in one-pot reactions. Herein, we demonstrate that multi-component MOFs with unprecedented complexity can be constructed in a predictable and stepwise manner under simple kinetic guidance, which conceptually mimics the retrosynthetic approach utilized to construct complicated organic molecules. Four multi-component MOFs were synthesized by the subsequent incorporation of organic linkers and inorganic clusters into the cavity of a mesoporous MOF, each composed of up to three different metals and two different linkers. Furthermore, we demonstrated the utility of such a retrosynthetic design through the construction of a cooperative bimetallic catalytic system with two collaborative metal sites for three-component Strecker reactions.
Having access to clean water is a mandatory requirement for the proper development of living beings. So, addressing the removal of contaminants from aquatic systems should be a primary research priority in order to re-establish ecosystem balance and secure a more sustainable future. The fascinating structures and striking physical properties of metal-organic frameworks (MOFs) have revealed them as excellent platforms for the removal of harmful species from water. In this review, we have focussed our attention on critically highlight the last developments achieved on the adsorptive removal of inorganic - metal cations, inorganic acids, oxyanions/cations, nuclear wastes and other inorganic anions - and organic - pharmaceutical and personal care products, artificial sweeteners and feed additives, agricultural products, organic dyes and industrial products - contaminants commonly found in wastewaters using MOFs technologies. In particular, we have attempted to give a clear insight on the different synthetic strategies for water remediation, stressing the wide tuneability of MOFs. For that purpose, we have classified these two classes of pollutants in different subfamilies, based on its chemical composition or common use. Finally, we have proposed some future trends and challenges that need to be addressed for widen the range of applicability of MOFs and make a solid headway towards a sustainable development.
Current technologies for removing heavy metal ions are typically metal ion specific. Herein we report the development of a broad-spectrum heavy metal ion trap by incorporation of ethylenediaminetetraacetic acid into a robust metal-organic framework. The capture experiments for a total of 22 heavy metal ions, covering hard, soft, and borderline Lewis metal ions, show that the trap is very effective, with removal efficiencies of >99% for single-component adsorption, multi-component adsorption, or in breakthrough processes. The material can also serve as a host for metal ion loading with arbitrary selections of metal ion amounts/types with a controllable uptake ratio to prepare well-dispersed single or multiple metal catalysts. This is supported by the excellent performance of the prepared Pd2+-loaded composite toward the Suzuki coupling reaction. This work proposes a versatile heavy metal ion trap that may find applications in the fields of separation and catalysis.
Many environmental pollutants inherently exist in their anionic forms and are therefore highly mobile in natural water systems. Cationic framework materials that can capture those pollutants are highly desirable but scarcely reported. Here we present a mesoporous cationic thorium-based MOF (SCU-8) containing channels with a large inner diameter of 2.2 nm and possessing a high surface area of 1360 m² g⁻¹. The anion-exchange properties of SCU-8 were explored with many anions including small oxo anions like ReO4⁻ and Cr2O7²⁻ as well as anionic organic dyes like methyl blue and the persistent organic pollutant, perfluorooctane sulfonate (PFOS). Both fast uptake kinetics and great sorption selectivity toward PFOS are observed. The underlying sorption mechanism was probed using quantum mechanical and molecular dynamics simulations. These computational results reveal that PFOS anions are immobilized in SCU-8 by driving forces including electrostatic interactions, hydrogen bonds, hydrophobic interactions, and van der Waals interactions at different adsorption stages.
Heavy metal ions are highly toxic and widely spread as environmental pollutants. New strategies are being developed to efficiently remove these toxic ions. Herein, we take the intrinsic advantages of metal-organic frameworks (MOFs) and develop a porous Zn(II)-based MOF decorated with O− groups for the removal of Pb2+. Benefiting from its multiple porosity, sufficient adsorption sites and strong affinity, the activated MOF material exhibits ultrahigh Pb2+ uptake capacity (616.64 mg g−1), surpassing all those of reported MOF adsorbents. Moreover, it can selectively capture Pb2+ with high efficiency (> 99.27%) against background ions. Even in the presence of high concentration of competitive ions, such as Ca2+ or Mg2+, effective removal (> 99.21%) can also be achieved in a short time. The excellent removal performance demonstrates the strong electrostatic attraction and coordination interaction between the highly accessible O− groups and Pb2+. The possible adsorption mechanism was systematically verified by zeta potential, FT-IR and XPS studies. Our work reveals the enormous potential of functionalized MOFs as an appealing platform to construct sorbent materials.
The residual presence of organic dyes in water resources or wastewater treatment systems, derived mainly from dumping of different industries, constitutes a major environmental problem with no easy answer. Here we report an eco‐friendly water‐stable metal‐organic framework ‐prepared from a derivative of the natural amino acid L‐serine‐ featuring functional channels densely decorated with the highly flexible L‐serine residues containing hydroxyl groups. The presence of such flexible and functional environment within the confined state of the MOF, leads to a very efficient removal from water of different organic dyes: The cationic Pyronin Y, Auramine O and Methylene Blue and the neutral Brilliant Green, as unveiled by the unprecedented snapshots offered by single crystal X‐ray diffraction. This MOF enables highly efficient water remediation, being capable to capture more than 90% of dye content, even at very low concentrations such as 10 ppm, which is similar to that usually found in industrial wastewaters. Remarkably, the removal efficiency is improved in simulated contaminated mineral water with multiple dyes.
We report a novel metal-organic framework (MOF) featuring functional pores decorated with hydroxyl groups derived from the natural amino acid L-serine, which is able to establish specific interactions of different nature, strength and directionality with organic molecules of technological interest, i.e. ascorbic acid, pyridoxine, bupropion and 17-beta-estradiol, based on its different size and chemical nature. The ability of 1 to distinctly organize guest molecules within its channels, through the concomitant effect of different directing supramolecular host-guest interactions, enable to have unique insights, by means of single-crystal X-ray crystallography, on the host-guest interactions. These results increase our understanding on molecular recognition processes at MOFs, opening a myriad of potential technological applications in the near future.
The gram‐scale synthesis, stabilization and characterization of well‐defined ultrasmall subnanometric catalytic clusters on solids represent a challenge. Here, we report the chemical synthesis and X‐ray snapshots of Pt20 clusters, homogenously distributed and densely‐packaged within the channels of a metal‐organic framework. This novel hybrid material catalyzes efficiently, and even most important from an economic and environmental viewpoint, at low temperature (25 to 140 ºC), energetically‐costly industrial reactions in the gas phase such as hydrogen cyanide (HCN) production, carbon dioxide (CO2) methanation and alkene hydrogenations. These results open the way for the design of precisely‐defined catalytically active ultrasmall metal clusters in solids for technically easier, cheaper and dramatically‐less dangerous industrial reactions.
The pollution of surface and groundwater with heavy metals is a serious global concern, both environmentally, as well as with respect to human health. Overabundance of these elements poses severe health risks for humans, and also for other life forms through bioaccumulation along food chains. Therefore, steps should be taken to reduce the amount of such elements in water to acceptable levels. This review looks at metal–organic frameworks (MOFs) which have been recently developed and studied for potential applications in heavy metal removal from water. We provide an overview of the current capabilities and important properties of MOFs used for this purpose.
We report the control of guest release profiles by dialing-in desirable interactions between guest molecules and pores in metal-organic frameworks (MOFs). The interactions can be derived by the rate constants that were quantitatively corre-lated with the type of functional group and its proportion in the porous structure, thus the release of guest molecules can be predicted and programmed. Specifically, three probe molecules (ibuprofen, rhodamine B, doxorubicin) were studied in a series of robust and mesoporous MOFs with multiple functional groups [MIL-101(Fe)-(NH2)x, MIL-101(Fe)-(C4H4)x and MIL-101(Fe)-(C4H4)x(NH2)1-x]. The release rate can be adjusted by 32 folds [rhodamine from MIL-101(Fe)-(NH2)x], and the time of release peak can be shifted by up to 12 days over a 40-day release period [doxorubicin from MIL-101(Fe)-(C4H4)x(NH2)1-x], which was not obtained in the physical mixture of the single component MOF counterparts nor in other porous materials. The co-release of two pro-drug molecules (ibuprofen and doxorubicin) was also achieved.