Anionic Metal Organic Framework Research Articles

Rational design of Bacteria-Targeted and Photo-Responsive MOF gel with antibacterial and anti-inflammatory function for infected wound healing

Damaged skin is prone to recurrent bacterial infections, which hinder proper wound healing and exacerbate inflammation. Urgent attention is required to devise versatile dressings possessing antibacterial and anti-inflammatory attributes to facilitate wound recovery. In this study, we engineered a photo-responsive metal–organic frameworks (MOFs) gel, targeting bacteria, and endowed it with antibacterial and anti-inflammatory effects to address infected wound healing. On the one hand, the anionic MOF was choose to support cationic natural drug Berberine (BBR) to achieve slow release of anti-inflammatory drugs. On the other hand, the incorporation of Ag nanoparticles onto MOFs not only facilitates the generation of reactive oxygen species (ROS) via photocatalysis under visible light but also furnishes sites for boric acid group attachment to target bacteria and expedites ROS transfer. The resultant MOFs@Ag-B@BBR exhibited potent photodynamic antibacterial activity against Staphylococcus aureus and MRSA at a low concentration of 37.5 µg mL−1, surpassing the efficacy of most reported MOFs-based nano-antimicrobials. Upon application of the MOFs@Ag-B@BBR composite hydrogel to infected wounds, the released BBR, in conjunction with photodynamic antibacterial action, significantly mitigated inflammatory responses and fostered wound healing. This study provides a widely applicable approach for rational design of MOFs materials with enhance antibacterial and anti-inflammatory functions.

Investigation of Anionic Metal–Organic Frameworks with Extra-Framework Cations for Room Temperature Hydrogen Storage

Investigation of Anionic Metal–Organic Frameworks with Extra-Framework Cations for Room Temperature Hydrogen Storage

An anionic metal-organic framework decorated with tartaric acid for enhanced adsorption of indium ions

Adsorption and recovery of indium (In) ions is highly important for the sustainable use of this valuable metal resource. This work reports the synthesis of a novel metal-organic framework (MOF) adsorbent, MOF-808-TA (TA, tartaric acid). The introduction of TA molecules was achieved through a post-synthesis exchange of TA and acetic acid that is initially in the clusters of MOF-808. MOF-808-TA exhibits a larger adsorption amount for In(III) ions (173.3 mg g−1) than the unmodified MOF-808 (57.5 mg g−1). Meanwhile, adsorption equilibrium time is 1–120 min at the concentration range of 0.2–40 mg L−1. Further experiments show that MOF-808-TA owns still a high removal ratio for In(III) ions upon the presence of some metal ions. Moreover, MOF-808-TA can be well regenerated with a slight loss of adsorption capacity after five adsorption-desorption cycles. X-ray photoelectron spectrometry (XPS), Fourier transform infrared (FTIR) spectroscopy, and density functional theory (DFT) calculation unveil the synergic chelation contribution of the aliphatic hydroxyl and carboxyl groups from TA molecules. Also, the use of TA leads to the formation of the negative charge property of MOF-808-TA, which induces an electrostatic interaction towards cationic In(III) ions. This work indicates the high potential of MOF-808-TA for the removal of In(III) ions from aqueous solutions.

Selective Sr2+ capture in an In3+-based anionic metal-organic framework

Strontium-90 (90Sr) has a long half-life (t1/2 = 28.8 years) and high β− decay energy (decay energy = 0.546 MeV), making it a hazardous radioactive pollutant. Various methods to remove 90Sr2+ from radioactive wastewater have been developed. Among them, the ion-exchange method has gained significant attention owing to its high capacity, simplicity, and cost-effectiveness. In this study, we synthesize a water-stable, anionic metal–organic framework, DGIST-12, assembled from In3+ and partially deprotonated 4,6-dihydroxy-1,3-benzenedicarboxylic acid. Furthermore, we evaluate the potential of DGIST-12 as a promising Sr2+ sorbent, highlighting its high porosity and a negatively charged In8 cluster. DGIST-12 effectively exchanges its counter cations, dimethylammonium, with Sr2+. Our findings suggest that the maximum Sr2+ uptake capacity of DGIST-12 is reached within 30 min of exposure, and this capacity is maintained across a broad pH range of 4–11. Importantly, DGIST-12 selectively adsorbs Sr2+ in the presence of various competing ions. Furthermore, the viability test performed on yeast cells exposed to Sr2+-containing media treated with DGIST-12 reveals that DGIST-12 can mitigate the harmful effects of Sr2+ toxicity on living organisms. These results underscore the promising prospects for creating innovative sorbent materials designed for the effective and discriminative removal of radioactive contaminants.

Anionic Ni-Based Metal-Organic Framework with Li(I) Cations in the Pores for Efficient C2H2/CO2 Separation.

Acetylene (C2H2) is widely used as a raw material for producing various downstream commodities in the petrochemical and electronic industry. Therefore, the acquisition of high-purity C2H2 from a C2H2/CO2 mixture produced by partial methane combustion or thermal hydrocarbon cracking is of great significance yet highly challenging due to their similar physical and chemical properties. Herein, we report an anionic metal-organic framework (MOF) named LIFM-210, which has Li+ cations in the pores and shows a higher adsorption affinity for C2H2 than CO2. LIFM-210 is constructed by a unique tetranuclear Ni(II) cluster acting as a 10-connected node and an organic ligand acting as a 5-connected node. Single-component adsorption and transient breakthrough experiments demonstrate the good C2H2 selective separation performance of LIFM-210. Theoretical calculations revealed that Li+ ions strongly prefer C2H2 to CO2 and are primary adsorption sites, playing vital roles in the selective separation of C2H2/CO2.

Fabrication of an anionic layered metal-organic framework for the efficient removal of Sr2+

Efficient removal of radioactive 90Sr from solutions is of vital importance due to its radioactive nature and high mobility. Herein, a 2D anionic metal-organic framework (MOF) [Me2NH2][KZn(pydc)2(H2O)2]∙H2O (K-Zn-MOF; pydc = 2,6-pyridinedicarboxylic acid) was synthesized and characterized. The prepared K-Zn-MOF was in turn applied for the removal of Sr2+ ions and various experimental conditions including contact time, initial concentration, and temperatures were optimized. Experimental findings revealed that the adsorption of Sr2+ on K-Zn-MOF reached equilibrium within 60 min at room temperature with Re = 95.39%. K-Zn-MOF exhibited ultra-high adsorption capacity (878.3 mg g−1), remarkable affinity (Kd = 5.8 × 105 mL g−1) in solutions and super-high selectivity in the presence of interfering coexisting ions (Na+, K+, Mg2+, and Ca2+). Mechanistic investigation suggested that free exchangeable [Me2NH2]+ ions and strong interactions between uncoordinated oxygens from COO− groups with target ions significantly contributed to the rapid adsorption of Sr2+ ions.

Nanotrap Grafted Anionic MOF for Superior Uranium Extraction from Seawater.

On-demand uranium extraction from seawater (UES) can mitigate growing sustainable energy needs, while high salinity and low concentration hinder its recovery. A novel anionic metal-organic framework (iMOF-1A) is demonstrated adorned with rare Lewis basic pyrazinic sites as uranyl-specific nanotrap serving as robust ion exchange material for selective uranium extraction, rendering its intrinsic ionic characteristics to minimize leaching. Ionic adsorbents sequestrate 99.8% of the uranium in 120 mins (from 20,000 ppb to 24 ppb) and adsorb large amounts of 1336.8mg g-1 and 625.6mg g-1 from uranium-spiked deionized water and artificial seawater, respectively, with high distribution coefficient, Kd U ≥ 0.97 × 106 mL g-1 . The material offers a very high enrichment index of ≈5754 and it achieves the UES standard of 6.0mg g-1 in 16 days, and harvests 9.42mg g-1 in 30 days from natural seawater. Isothermal titration calorimetry (ITC) studies quantify thermodynamic parameters, previously uncharted in uranium sorption experiments. Infrared nearfield nanospectroscopy (nano-FTIR) and tip-force microscopy (TFM) enable chemical and mechanical elucidation of host-guest interaction at atomic level in sub-micron crystals revealing extant capture events throughout the crystal rather than surface solely. Comprehensive experimentally guided computational studies reveal ultrahigh-selectivity for uranium from seawater, marking mechanistic insight.

An anionic MOF as a multifunctional platform for selective adsorption of CO2, separation of organic dyes and ionic conductivity

It is a very effective strategy to capture and separate carbon dioxide by incorporation of alkali cations into MOFs. Presented here is an anionic metal-organic framework (MOF) (Me2NH2)2Co(tpta)·2H2O (1), in which the exchange of alkali ions (Li+ and Na+) took place with H2N(Me)2+ cations. As expected, CO2/N2 selectivity of the framework was improved significantly and reached 61.6 due to the inclusion of Li + using the ideal adsorbed solution theory (IAST) model. The enhancement of its CO2 uptake capability and selectivity has been mainly attributed to the charge-quadrupole interaction. For the CO2/N2 system, it is found that the inclusion of Li+ rather than Na+ favors higher selectivity. Additionally, it successfully separated cationic dye crystal violet (CV+) from anionic dye methyl orange (MO−) by the column-chromatography. Evidently, the enhancement of the electrostatic interaction greatly improves the separation performance of the framework.

Bilayer Zwitterionic Metal-Organic Framework for Selective All-Solid-State Superionic Conduction in Lithium Metal Batteries.

Solid-state batteries (SSBs) hold immense potential for improved energy density and safety compared to traditional batteries. However, existing solid-state electrolytes (SSEs) face challenges in meeting the complex operational requirements of SSBs. In this study, weintroduce a novel approach to address this issue by developing a metal-organic framework (MOF) with customized bilayer zwitterionic nano-channels (MOF-BZN) as high-performance SSEs. The bilayer zwitterionic nano-channels consist of a rigid anionic MOF channel with chemically grafted soft multi-cationic oligomers (MCOs) on the pore wall. This design enables selective superionic conduction, with MCOs restricting the movement of anions while coulombic interaction between MCOs and anionic framework promoting the dissociation of Li+ . MOF-BZN exhibits remarkable Li+ conductivity (8.76 × 10-4 S cm-1 ), high Li+ transference number (0.75), and a wide electrochemical window of up to 4.9V at 30°C. Ultimately, the SSB utilizing flame retarded MOF-BZN achieves an impressive specific energy of 419.6Wh kganode+cathode+electrolyte -1 under constrained conditions of high cathode loading (20.1mg cm-2 ) and limited lithium metal source. The constructed bilayer zwitterionic MOFs presents a pioneering strategy for developing advanced SSEs for highly efficient SSBs. This article is protected by copyright. All rights reserved.

Tunable White Light Emission of a Metal-Organic Framework Based on a Bisquinoxaline Derivative by Introducing Red-Green Cationic Dyes.

The unique structural advantages give metal-organic frameworks (MOFs) a special use as host substrates to encapsulate organic dyes, which would result in specific host-guest composites for white-light phosphors. In this work, an anionic MOF exhibiting blue emission was constructed using bisquinoxaline derivatives as photoactive centers, which could effectively encapsulate rhodamine B (Rh B) and acriflavine (AF) to form an In-MOF ⊃ Rh B/AF composite. By simply adjusting the amount of Rh B and AF, the emitting color of the resulting composite could be easily adjusted. The formed In-MOF ⊃ Rh B/AF composite exhibits broadband white light emission with ideal Commission International ed'Eclairage (CIE) coordinates of (0.34, 0.35), a color rendering index of 80.8, and a moderately correlated color temperature value of 5193.96 K. This strategy can be easily extended to other blue-emitting MOFs and dyes, thus opening up new prospects for the development of white-light-emitting materials.

Enhancement of catalytic activity for hydrogenation of nitroaromatic by anionic metal-organic framework

Nitroaromatic hydrogenation catalysis without precious metals remains a longstanding challenge. The rate of electron transfer is the crucial factor affecting hydrogenation catalysis. Herein, an ionic Cd-based metal-organic framework (I-Cd-MOF) exhibiting a unique structure with one-dimensional (1D) opening nanochannels and good electron transfer ability was synthesized for catalyzing hydrogenation of 4-nitrophenol (4-NP). The catalytic activity of the unique I-Cd-MOF without noble metals is detected, which is higher than most reported noble metal catalysts. Remarkably, the reaction rate of I-Cd-MOF (4.28 min−1) is about 47.6 times higher than that of the Cd-based neutral MOF (N-Cd-MOF) with the similar crystalline structure. Liquid chromatograph mass spectrometer (LC-MS) and theoretical results demonstrate that 4-NP and five intermediates are stabilized in the channels of I-Cd-MOF, which increases the possibility of contact with H* and H2 generated at the Cd sites. The I-Cd-MOF was extended to other nitroaromatic hydrogenation catalysis, which still displays excellent activity. More importantly, the I-MOF@Filter membrane was successfully constructed for continuous hydrogenation catalytic reactions, which maintains a high catalytic performance after 7 cycles of recycling without washing. This work fills in the application of the I-MOFs in hydrogenation catalytic reactions and provides an effective way for the rapid and green degradation of nitroaromatic compounds.

Isoelectric Substitution Strategy to Construct a Partially Charged MOF for C2H2 Capture and Selective Dye Adsorption

The charged metal–organic framework (MOF) (anionic and cationic MOF) material plays an important role in gas adsorption and separation and ecological environment management. Herein, we reported a partially charged Mg-based MOF (FJU-129) with dimethylamine counterions, which can efficiently separate C2H2 from CO2 and rapidly adsorb the cationic dye methylene blue (MB). FJU-129a showed a high uptake capacity of up to 133.8 cm3/g for C2H2 at 273 K, 1 bar, and low isosteric heat of adsorption of C2H2 (24.78 kJ/mol). The C2H2/CO2 separation is validated by a dynamic breakthrough experiment at 296 K, 1.5 bar, and the Grand Canonical Monte Carlo simulation revealed that the partially remaining charge on the magnesium sites has an electrostatic force on the −C≡C– bond of C2H2 molecules, and C–H···π interactions play an important role in the separation of C2H2/CO2 selective mixtures. In addition, owing to the pore size and electrostatic effect, FJU-129 selectively absorbs MB and excludes other cationic dyes and anionic dyes (MB, CV, RB, R6G, MO, and SD-III).

Silver Ion-Exchanged Anionic Metal–Organic Frameworks for Iodine Adsorption: Silver Species Evolution from Ions to Nanoparticles

Ag clusters and nanoparticles have attracted much attention in the fields of environmental catalysis and pollutant removal. It is a common strategy to fabricate highly dispersed Ag nanoparticles in porous scaffolds via in situ growth. Here, anionic metal–organic frameworks (MOFs) have been employed to provide robust supports for Ag species. Ag nanoparticles with well-defined sizes are observed in MOFs when internal NH2Me2+ is exchanged with extrinsic Ag+ ions. The extended X-ray absorption fine structure and X-ray photoelectron spectroscopy spectra confirm that about 20% of Ag+ are reduced into Ag0, while the rest 80% are still Ag+ species. The comparison of Ag loading into anionic and neutral Cu-BTC MOFs suggests that the exchangeable cations facilitate Ag+ migration into the interior of MOFs and thus alleviate its aggregation and spontaneous reduction. Besides, the adsorption tests verify that all the Ag species in MOFs are accessible to iodine vapor to form AgI. The charge transfer from frameworks to trapped iodine and the water in the air promote the formation of iodide ions, which react with Ag+ to produce AgI. The iodine adsorption performance of MOF beads was also evaluated using the pore diffusion model. This work provides insights into the evolution of Ag species in MOFs and potential Ag-based adsorbents for radioiodine capture.

A light-sensitive metal-organic framework composite encapsulated by ion exchange for photocatalytic organic reaction

In this work, ZJU-28, a typical anionic metal-organic framework, was selected as the functional carrier to encapsulate [Ir(ppy)2bpy]+ (ppy ​= ​2-phenylpyridine, bpy ​= ​2,2′-bipyridine) cation through ion exchange, and a new composite photocatalyst [Ir(ppy)2bpy]+@ZJU-28 was obtained therefore. The composite material was detailly characterized by powder X-ray diffraction (PXRD), fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), UV–Vis (UV) absorption spectra and ICP-OES. [Ir(ppy)2bpy]+@ZJU-28 showed favorable photocatalytic activity for visible light promoted organic transformations. More importantly, it exhibited super stability and excellent recovery & reuse performance.

Ion Selective Bifunctional Metal–Organic Framework-Based Membrane for Lithium Metal-Based Nonaqueous Redox Flow Battery

Nonaqueous redox flow batteries (NARFBs) hold potential application as an electricity energy storage for intermittent renewable energy and can operate with high voltage and energy density. However, their further development is impeded by lack of a proper membrane. Herein, a flexible freestanding anionic metal–organic framework (MOF)-based membrane is prepared through a solution casting method, with an anionic MOF (UiO-66-SO3Li) and polyvinylidene fluoride. The prepared membrane shows an impressive ionic selectivity (37.6) of Li+ to N-(ferrocenylmethyl)-N,N-dimethyl-N-ethylammonium (Fc1N112+) ions and high ionic conductivity. Benefiting from the unique micropore structure of MOF and the anionic transport channels of Li+ across the membrane, the resultant Li-based hybrid NARFB delivers a high-capacity retention (99.95% per cycle) over 500 cycles with a well-assembled stable interphase after long time lithium plating/stripping, which decreases the voltage efficiency during the cycling. Calculations reveal that the membrane easily desolvates Li+ in the unique micropore structure of MOF before Li deposition occurs, which suppresses parasitic reaction and accelerates Li uniform deposition. This work provides a viable method to design bifunctional NARFB membranes which achieve ion sieving and ion exchange functions.

Cation-Exchange in Metal-Organic Framework as a Strategy to Obtain New Material for Ascorbic Acid Detection.

Ascorbic acid (AA) is an important biomolecule, the deficiency or maladjustment of which is associated with the symptoms of many diseases (e.g., cardiovascular disease or cancer). Therefore, there is a need to develop a fluorescent probe capable of detecting AA in aqueous media. Here, we report the synthesis, structural, and spectroscopic characterization (by means of, e.g., XRD, XPS, IR and Raman spectroscopy, TG, SEM, and EDS analyses), as well as the photoluminescent properties of a metal-organic framework (MOF) based on Cu2+ and Eu3+ ions. The ion-exchange process of the extraframework cation in anionic Cu-based MOF is proposed as an appropriate strategy to obtain a new material with a nondisturbed structure and a sensitivity to interaction with AA. Accordingly, a novel Eu[Cu3(μ3-OH)(μ3-4-carboxypyrazolato)3] compound for the selective optical detection of AA with a short detection time of 5 min is described.

(Digital) Ionic Conduction Mechanism and Design of Metal–Organic Framework Based Quasi-Solid-State Electrolytes

Recently, anionic metal–organic frameworks (MOFs) with superior ionic conductivity and Li+ transference numbers have opened a new avenue in the development of quasi-solid-state electrolytes (QSSEs). Given the superior performance and the characterization challenges associated with transport property measurements, it is vitally important to understand the Li+ transport and conduction mechanisms of this new prototype of QSSEs. In this presentation, we will discuss the theoretical and experimental investigation of two polyoxometalate (POM) -based MOFs, [(MnMo6)2(TFPM)] imine and [(AlMo6)2(TFPM)] imine , as QSSEs. Classical molecular dynamics coupled with quantum chemistry and grand canonical Monte Carlo are utilized to model the corresponding diffusion and ionic conduction in the two materials. Using different approximate levels of ion diffusion behavior, the primary ionic conduction mechanism was identified as solvent-assisted hopping (>77%), revealing the critical role of the solvent in MOF-based QSSEs. Detailed static and dynamic solvation structures were obtained to interpret Li+ motion with high spatial and temporal resolution. We found that the local charge distribution on POM surface largely determines the interaction between Li+ and the framework. Based on the prevalent mechanism of Li+ motion, we propose a hypothesized MOF design with a non-interpenetrating structure that is expected to achieve 6–8 times better ionic conduction performance (1.6–1.7 mS cm−1) than the current state-of-the-art (0.19–0.35 mS cm−1), approaching the conductivity range of liquid electrolytes. Figure 1

Luminol immobilized on the metal–organic framework: As an efficient and highly sensitive sensor for the detection of antibiotics in aqueous medium

In this research, an anionic metal–organic framework (MOF) with the general formula of [HDMA]2[Zn2(BDC)3(DMA)2]·6DMF (HDMA+: dimethylamonnium, BDC2−: 1,4‐benzenedicarboxilate, DMA: dimethylamine, and DMF: N,N′‐dimethylformamide), namely, TMU‐3, was synthesized by the solvothermal method and then modified with the chemiluminescent reagent of luminol via post‐synthetic modification. The Luminol@TMU‐3 was incorporated as an ideal sensor for the immediate detection of four kinds of antibiotics such as cephalexin, amoxicillin, ampicillin, and 6‐aminopenicillanic acid (6‐APA) in aqueous media. Based on the results, Luminol@TMU‐3 exhibits high throughput and high efficiency of luminescent intensity, and the limit of detection (LOD) of cephalexin (in the 0.001 to 1000 μM concentration range), amoxicillin (in the 0.05 to 100 μM concentration range), ampicillin (in the 0.05 to 100 μM concentration range), and 6‐APA (in the 0.001 to 500 μM concentration range) is estimated to be 0.00005, 0.0001, 0.00012, and 0.00003 μM, respectively. High sensitivity, high throughput, and high fidelity are some of the notable features of this unique diagnostic platform, which can act as a universal device in the quantitative and rapid recognition of a wide range of analytes.

Anionic metal-organic framework modified separator boosting efficient Li-ion transport

Low lithium ion (Li+) mobility and thermal stability of polyolefin separator are crucial obstacles that limit the utilization of Li metal electrodes in the age of rapid acceleration toward high-energy-density rechargeable batteries. Herein, we report anionic metal-organic frameworks (MOFs) modified separator to overcome the barriers. By grafting –SO3− group onto the Universitetet i Oslo (UIO) structure, the anionic MOFs nanoparticles are synthesized (noted as UIO-SOLi). The UIO-SOLi is adhered on the surface of Celgard 2400 via polyacrylic acid (PAA) to fabricate the modified separator (UIOSOL@PP). The MOFs coating optimizes the wettability and thermal stability of the pristine separator. Negatively charged moieties –SO3− within the pore surface electrostatically repel anions while facilitate the transport of Li+, thus achieving a high Li+ transference number (tLi+) of 0.82. The effective Li+ transport relieves the concentration polarization, regulates the Li+ flow and realizes the uniform deposition of lithium. By implementing the UIOSOL@PP separator, the LiFePO4|Li cells deliver superior rate performance and cycling lifespan that renders a high discharge capacity retention of 155 mAh g−1 over 600 cycles at 1C. These results indicate that anionic MOFs modified separator is a promising strategy to modulate Li+ flow and assist with efficient long-term operation of lithium metal batteries.

Highly Efficient MOF-Driven Silver Subnanometer Clusters for the Catalytic Buchner Ring Expansion Reaction.

The preparation of novel efficient catalysts—that could be applicable in industrially important chemical processes—has attracted great interest. Small subnanometer metal clusters can exhibit outstanding catalytic capabilities, and thus, research efforts have been devoted, recently, to synthesize novel catalysts bearing such active sites. Here, we report the gram-scale preparation of Ag20 subnanometer clusters within the channels of a highly crystalline three-dimensional anionic metal–organic framework, with the formula [Ag20]@AgI2NaI2{NiII4[CuII2(Me3mpba)2]3}·48H2O [Me3mpba4– = N,N′-2,4,6-trimethyl-1,3-phenylenebis(oxamate)]. The resulting crystalline solid catalyst—fully characterized with the help of single-crystal X-ray diffraction—exhibits high catalytic activity for the catalytic Buchner ring expansion reaction.