Metal-organic Framework Framework Research Articles

Zr‐MOF nanosheets featuring benzothiadiazoles enable efficient visible light driven photooxidation of sulfides and amines

Ultrathin zirconium‐based metal–organic framework (MOF) nanosheets, embedded with photochromic units, are expected to be highly efficient heterogeneous photocatalysts, thanks to their rich catalytic sites, short diffusion paths, and effective separation of photogenerated charge carriers. Herein, we reported the synthesis of novel Zr‐MOF nanosheets (Zr‐BTDB) through a solvothermal synthesis that integrates benzothiadiazole (BTz) as a photochromic moiety within the framework of MOF. The Zr‐BTDB nanosheets processes a [Zr12(μ3‐O)8(μ3‐OH)8(μ2‐OH)6] cluster with hcp topology. Importantly, Zr‐BTDB nanosheets exhibit excellent photocatalytic activity for the photooxidation of sulfides and amines at room temperature under blue light irradiation. Notably, these nanosheets maintain their photocatalytic activity and selectivity for up to five cycles without significant loss of activity and crystallinity. Systematical catalytic reactions revealed that the Zr‐BTDB nanosheets enable the generation of singlet oxygen (1O2) and superoxide radical (O2•–) under visible light irradiation, which is critical reactive oxygen species for the photooxidation of sulfides and benzylamines. Our work represents a straightforward route for the preparation of ultrathin, water stable, and visible‐light‐activated Zr‐MOF nanosheets, offering new potentials for the selective photooxidation of sulfides and amines in an eco‐friendly way.

Tunable Gas Admission via a "Molecular Trapdoor" Mechanism in a Flexible Cationic Metal-Organic Framework Featuring 1D Channels.

Achieving high gas selectivity is challenging when dealing with gas pairs of similar size and physiochemical properties. The "molecular trapdoor" mechanism discovered in zeolites holds promise for highly selective gas adsorption separation but faces limitations like constrained pore volume and slow adsorption kinetics. To address these challenges, for the first time, a flexible metal-organic framework (MOF) featuring 1D channels and functioning as a "molecular trapdoor" material is intoduced. Extra-framework anions act as "gate-keeping" groups at the narrowest points of channels, permitting gas admissions via gate opening induced by thermal/pressure stimuli and guest interactions. Different guest molecules induce varied energy barriers for anion movement, enabling gas separation based on distinct threshold temperatures for gas admission. The flexible framework of Pytpy MOFs, featuring swelling structure with rotatable pyridine rings, facilitates faster gas adsorption than zeolite. Analyzing anion properties of Pytpy MOFs reveals a guiding principle for selecting anions to tailor threshold gas admission. This study not only overcomes the kinetic limitations related to gas admission in the "molecular trapdoor" zeolites but also underscores the potential of developing MOFs as molecular trapdoor adsorbents, providing valuable insights for designing ionic MOFs tailored to diverse gas separation applications.

Introducing sulfonic acid polymers into MOF nanochannels for ultra-high Ba2+ adsorption capacity and proton conductivity

Porous materials with a high concentration of sulfonic acid groups are highly desirable for applications such as radioactive Ba2+ adsorption, catalysis, and proton-conductive materials, but they are also challenging to synthesize. In this work, we introduce polymers containing sulfonic acid groups into the nanochannels of metal–organic frameworks (MOFs) through in-situ synthesis to enhance the sulfonic acid content. We use a alkene with sulfonic acid groups (2)-acrylamido-2-methylpropane sulfonic acid, AMPS) and a crosslinking agent N,N’-methylenebisacrylamide (MBAA) to synthesize two MOF composites, PAMPS@MIL-101 and PAMPS@MIL-101-SO3H, in the ultra-stable MIL-101 series through in-situ polymerization with free radical initiators. The two MOF composites have a high and uniform distribution of sulfonic acid groups in the MOF framework, which results in ultra-high barium ion adsorption capacity. The maximum adsorption amounts are 142.7 and 356.9 mg·g−1 for PAMPS@MIL-101 and PAMPS@MIL-101-SO3H, respectively, which are higher than those of most reported adsorbents. Importantly, the adsorption equilibrium can be achieved within 20 min. Moreover, both MOF composites, PAMPS@MIL-101 and PAMPS@MIL-101-SO3H, exhibit super proton conductivity, with values of 6.43 × 10−2 S·cm−1 and 1.43 × 10−1 S·cm−1 at 85 °C and 98 % RH, respectively. This method offers a new way of modifying MOF nanochannels with high sulfonic acid concentrations, and opens up new opportunities for developing radioactive Ba2+ adsorption materials and proton-conductive materials.

Efficient Ethane and Propane Separation from Natural Gas Using Heterometallic Metal-Organic Frameworks with Interpenetrated Structures.

The development of efficient technology for natural gas separation in industrial processes has become imperative. In this regard, the exploration of novel and effective adsorbents has gained significant attention. One promising approach is the metal regulation of metal-organic frameworks (MOFs), particularly heterometallic MOFs, which offer greater potential for gas separation due to their diverse composition. This study presents the synthesis of a series of iron- and vanadium-based heterometallic MOFs (MIL-126), featuring interpenetrated structures, and investigates their adsorption performance for methane (CH4), ethane (C2H6), and propane (C3H8). Experimental results reveal that the choice of metal combinations within the MOF framework significantly influences the adsorption performance of MIL-126. Notably, heterometallic MIL-126(Fe/Ni) exhibits a stronger binding affinity for C3H8, with an impressive uptake of 177 cm3/g. The C3H8/CH4 ideal adsorbed solution theory selectivity of MIL-126(Fe/Ni) surpasses that of MIL-126(Fe) by a factor of 7, reaching a value of 853, second only to the highest reported value. Furthermore, MIL-126(Fe/Ni) exhibits remarkable potential for the recovery of pure CH4 from the equimolar C3H8/CH4 mixture, with the amount of pure CH4 approaching the maximum reported value for MOFs. Insights from isosteric heat at zero loading and Henry's coefficients indicate that the transformation of metal types leads to a change in the interaction energy between C3H8 and the framework. Furthermore, breakthrough experiments validate the effective separation capability of MIL-126(Fe/Ni) for CH4/C2H6/C3H8 mixtures. These findings underscore the remarkable potential of heterometallic MOFs in constructing a wide range of new MOFs with tailorable properties, thereby enhancing their gas separation performance.

Conjugated Microporous Polymers for Catalytic CO2 Conversion.

Rising carbon dioxide (CO2) levels in the atmosphere are recognized as a threat to atmospheric stability and life. Although this greenhouse gas is being produced on a large scale, there are solutions to reduction and indeed utilization of the gas. Many of these solutions involve costly or unstable technologies, such as air-sensitive metal-organic frameworks (MOFs) for CO2 capture or "non-green" systems such as amine scrubbing. Conjugated microporous polymers (CMPs) represent a simpler, cheaper, and greener solution to CO2 capture and utilization. They are often easy to synthesize at scale (a one pot reaction in many cases), chemically and thermally stable (especially in comparison with their MOF and covalent organic framework (COF) counterparts, owing to their amorphous nature), and, as a result, cheap to manufacture. Furthermore, their large surface areas, tunable porous frameworks and chemical structures mean they are reported as highly efficient CO2 capture motifs. In addition, they provide a dual pathway to utilize captured CO2 via chemical conversion or electrochemical reduction into industrially valuable products. Recent studies show that all these attractive properties can be realized in metal-free CMPs, presenting a truly green option. The promising results in these two fields of CMP applications are reviewed and explored here.

Sustainable lithium extraction enabled by responsive metal-organic frameworks with ion-sieving adsorption effects

Metal-organic frameworks (MOFs) are superior ion adsorbents for selectively capturing toxic ions from water. Nevertheless, they have rarely been reported to have lithium selectivity over divalent cations due to the well-known flexibility of MOF framework and the similar physiochemical properties of Li+ and Mg2+. Herein, we report an ion-sieving adsorption approach to design sunlight-regenerable lithium adsorbents by subnanoporous MOFs for efficient lithium extraction. By integrating the ion-sieving agent of MOFs with light-responsive adsorption sites of polyspiropyran (PSP), the ion-sieving adsorption behaviors of PSP-MOFs with 6.0, 8.5, and 10.0 Å windows are inversely proportional to their pore size. The synthesized PSP-UiO-66 with a narrowest window size of 6.0 Å shows high LiCl adsorption capacity up to 10.17 mmol g-1 and good Li+/Mg2+ selectivity of 5.8 to 29 in synthetic brines with Mg/Li ratio of 1 to 0.1. It could be quickly regenerated by sunlight irradiation in 6 min with excellent cycling performance of 99% after five cycles. This work sheds light on designing selective adsorbents using responsive subnanoporous materials for environmentally friendly and energy-efficient ion separation and purification.

An Assessment of Metal-Organic Frameworks and Activated Carbon Solutions for Sustainable Hydrogen Gas Storage

The pursuit of sustainable energy sources has elevated hydrogen gas as a potential carbon-neutral fuel with high energy content. However, efficient storage and transportation of hydrogen pose considerable challenges. To address these issues, the utilisation of metal-organic frameworks (MOFs) and activated carbon (AC) for hydrogen storage through adsorption has gained substantial attention. This research article offers a comprehensive assessment of hydrogen storage using these materials.
 The adsorption mechanism, fundamental to hydrogen storage in MOFs, involves hydrogen molecules adhering to the MOF framework's surface and pores via intermolecular forces. MOFs, comprising metal nodes and organic linkers, present high surface area-to-volume ratios and customizable adsorption properties, making them appealing for gas storage. AC, an amorphous porous carbon form, also displays favourable traits for gas storage.

Post‐synthetic modifications in metal–organic frameworks for high proton conductivity

AbstractA myriad of metal ions and organic linkers can be used to produce metal–organic frameworks (MOFs) with varied functionalities, porosities, and dimensionalities. Such diversity has garnered significant research interest, particularly in leveraging MOFs as proton conductors for fuel cells. One effective approach involves introducing guest molecules into MOF pores. These molecules serve either as proton carriers or as proton‐conducting media through potential hydrogen bonding networks. This review offers an organized overview of key methodologies historically employed to achieve superprotonic conductivity in MOFs. The article systematically categorizes these tactics into three primary groups: guest molecule encapsulation, modulation at metal‐coordination sites, and ligand functionalization. We succinctly discuss the roles of proton carriers, conducting media, and the overall MOF framework, emphasizing the significance of each strategy's application. In conclusion, we provide insights into the future development of MOFs as proton conductors, rooted in the categorization and conceptual understanding of these strategies.

Prediction of Carbon Dioxide and Methane Adsorption on UiO-66 Metal–Organic Framework via Molecular Simulation

The adsorption equilibrium of methane (CH4) and carbon dioxide (CO2) on the metal–organic framework (MOF) UiO-66 is studied via molecular simulation. UiO-66 is a versatile MOF with vast potential for various adsorption processes, such as biogas upgrading, CO2 capture, and natural gas storage. The molecular simulations employ the grand canonical Monte Carlo (GCMC) method, covering a temperature range of 298–343 K and pressures up to 70 bar for CH4 and 30 bar for CO2. The accuracy of different forcefields in describing the adsorption equilibria is evaluated. Two modelling approaches are explored: (i) lumping each hydrogen atom in the MOF framework to the heavy atom it is bonded to (united atom approximation) and (ii) considering explicit hydrogen atoms. Additionally, the influence of electrical charges on CO2 adsorption is also evaluated. The findings indicate that the most effective forcefield to describe the adsorption equilibrium is a united atom forcefield based on the TraPPE parametrization. This approach also yields an accurate calculation of the isosteric heat of adsorption. In the case of CO2, it is observed that the use of electrical charges enhances the prediction of the heat of adsorption, especially in the low-coverage region.

Water-assisted hydrogen spillover in Pt nanoparticle-based metal–organic framework composites

Hydrogen spillover is the migration of activated hydrogen atoms from a metal particle onto the surface of catalyst support, which has made significant progress in heterogeneous catalysis. The phenomenon has been well researched on oxide supports, yet its occurrence, detection method and mechanism on non-oxide supports such as metal–organic frameworks (MOFs) remain controversial. Herein, we develop a facile strategy for efficiency enhancement of hydrogen spillover on various MOFs with the aid of water molecules. By encapsulating platinum (Pt) nanoparticles in MOF-801 for activating hydrogen and hydrogenation of C=C in the MOF ligand as activated hydrogen detector, a research platform is built with Pt@MOF-801 to measure the hydrogenation region for quantifying the efficiency and spatial extent of hydrogen spillover. A water-assisted hydrogen spillover path is found with lower migration energy barrier than the traditional spillover path via ligand. The synergy of the two paths explains a significant boost of hydrogen spillover in MOF-801 from imperceptible existence to spanning at least 100-nm-diameter region. Moreover, such strategy shows universality in different MOF and covalent organic framework materials for efficiency promotion of hydrogen spillover and improvement of catalytic activity and antitoxicity, opening up new horizons for catalyst design in porous crystalline materials.

Guest molecule engineered pore aperture of a yttrium-based metal–organic framework for efficient 1,3-butadiene separation from C4 hydrocarbons

Molecular sieving separation of 1,3-butadiene (C4H6) from C4 hydrocarbons is a highly desired method for C4H6 purification while it is still a challenge to finely tune the pore aperture size of metal–organic framework (MOF) adsorbent. To develop molecular-sieving MOFs for gas separation, most efforts mainly focus on the precise control of intrinsic window size of MOF framework while little effort has focused on regulating the pore size of MOF by guest molecule. In this work, we report the guest molecule engineered pore aperture strategy of MOF for molecular-sieving separation of C4H6 from other C4 hydrocarbons. As a proof-of-concept experiment, the aperture pore structure of a robust yttrium-based Y-abtc (abtc = 3, 3′, 5, 5′-azobenzene-tetracarboxylate) was adjusted by the controlled decomposition of the trapped dimethylamine cations in the pores. The optimal Y-abtc-160, which was obtained by treating the as-synthesized Y-abtc sample at 160 °C, exhibits typical type I adsorption isotherm for C4H6 at 298 K while other C4 components are excluded by size exclusion effect even at 1 bar. The C4H6 uptake in Y-abtc-160 is up to 49.5 cm3 g−1 at 1 bar, which exceeds all the reported adsorbents with ideal molecular-sieving effect. The column breakthrough experiments verify the efficient separation of C4H6/n-C4H8, C4H6/iso-C4H8, C4H6/n-C4H10, and C4H6/iso-C4H10 binary mixtures. In addition, Y-abtc-160 MOF has good regeneration ability and excellent chemical stability, implying great potential for the practical separation of C4H6 from other C4 hydrocarbons.

Emerging Pristine MOF-Based Heterostructured Nanoarchitectures: Advances in Structure Evolution, Controlled Synthesis, and Future Perspectives.

Metal-organic frameworks (MOFs) can be customized through modular assembly to achieve a wide range of potential applications, based on their desired functionality. However, most of the initially reported MOFs are limited to microporous systems and are not sufficiently stable, which restricts their popularization. Heterogeneity is introduced into a simple MOF framework to create MOF-based heterostructures with fascinating properties and interesting functions. Heterogeneity can be introduced into the MOFs via postsynthetic/ligand exchange. Although the ligand exchange has shown potential, it is difficult to precisely control the degree of exchange or position. Among the various synthesis strategies, hierarchical assembly is particularly attractive for constructing MOF-based heterostructures, as it can achieve precise regulation of MOF-based heterostructured nanostructures. The hierarchical assembly significantly expands the compositional diversity of MOF-based heterostructures, which has high elasticity for lattice matching during the epitaxial growth of MOFs. This review focuses on the synthetic evolution mechanism of hierarchical assemblies of MOF-based nanoarchitectures. Subsequently, the precise control of pore structure, pore size, and morphology of MOF-based nanoarchitectures by hierarchical assembly is emphasized. Finally, possible solutions to address the challenges associated with heterogeneous interfaces are presented, and potential opportunities for innovative applications are proposed.

Controlled Growth of a Photocatalytic Metal–Organic Framework on Conductive Plates by Mixing Direct Synthesis and Postsynthetic Modification Strategies

In this work, we develop a two-step process for the controlled growth of a thin layer of a functionalized and photosensitive metal–organic framework (MOF), namely Ru–Ti–UiO-67, on the surface of a plate coated with indium tin oxide (ITO), a transparent conductive oxide (TCO). In the first step, the in situ controlled growth of a layer of UiO-67-based MOF doped with a photosensitizer (ruthenium complex), herein referred to as Ru–UiO-67, is carried out on the surface of the ITO-coated plate, leading to Ru–UiO-67/ITO. The obtained MOF layer is relatively thin, allowing increased interactions between the MOF material and the TCO surface, and consists of crystals in the near-nanometer particle size. In the second step, a postsynthetic modification (PSM) process is applied to Ru–UiO-67/ITO to integrate Ti catalytic sites into the MOF framework, leading to Ru–Ti–UiO-67/ITO (containing both the photosensitizer and catalyst) while maintaining the MOF’s structure and morphology in addition to its strong interaction with the substrate. Importantly, on the synthetic level, this work demonstrates the possibility to form a homogeneous surface anchored with MOF on a transparent conductive surface, whereby the obtained MOF layer is strongly bound to the substrate and postsynthetic chemical modifications are enabled without any loss of material. Furthermore, the obtained material is proven to exhibit an efficient visible-light-driven photodegradation activity in aqueous solution.

Graphene quantum dots decorated MIL-100(Fe) composites for dye degradation

The present work outlines the synthesis of a visible light responsive photocatalyst by incorporating graphene quantum dots (GQD) in an iron-based metal organic framework (MOF) (i.e., MIL-100(Fe). The composite was synthesized via one-pot solvothermal approach and applied for degradation of Congo red (CR) dye from contaminated water. The composite was characterized in terms of structure, functionality, morphology, and optical properties. Noteworthy, the composite showed significant improvement in the photocatalytic activity in comparison with nascent MIL-100(Fe). Incorporation of GQD in the MOF framework resulted in increased surface area and pore volume and reduced PL intensity. MIL-100/GQD showed maximum dye degradation of 93.8% within 5 min of contact time using photocatalyst dose of 0.025 g/L. The incorporation of GQD resulted in increased charge separation between holes and electrons compared to pre MIL-100 (Fe) as evident from the PL spectra. The Mott-Schottky plot and the trapping experiment demonstrated that the active species like h+ and ̇O2− were responsible for degradation of CR dye. The photocatalyst exhibited appreciable reusability even after four cycles of reuse.

Construction of biomimetic proton transport channels in metal-organic framework

Construction of proton transport channels in metal-organic frameworks (MOFs) with simple synthesis processes, high proton conductivities and good performance stabilities has been of great interest for proton exchange membrane fuel cell (PEMFC). Herein, we mimic the proton transport behavior of amino acid residues in bacteriorhodopsin, select UiO-66-COOH as the host, glycine and aspartic acid as the functional guest molecules, and then functionalize the MOF framework with amino acids to obtain biomimetic proton transport channels. This strategy endows UiO-66-COOH-Asp a high proton conductivity of 1.19 × 10−2 S/cm at 70 °C and 98% RH, excellent cycle stability of performances and performance durability, which can be comparable to the reported MOFs-based proton conductors. Moreover, the proton conduction mechanism in UiO-66-COOH-Asp is elaborated in detail due to its visual structure, which is also one of the advantages of adopting MOFs as research platform, making it possible to optimize the structure-activity relationship of advanced materials. Notably, this strategy has clear objectives and simple synthesis, which has made certain contributions to both theoretical research and future industrial production of proton conductors.

Peroxidase-like biomimetic epoxidation and subsequent alcoholysis of olefins by Fe(III)tetrakis(4-sulphonatophenyl) porphyrin (Fe4SP) encapsulated in the metal-organic framework HKUST-1

The efficiency and diverse functionality of biological catalysts has inspired the synthetic design of systems to mimic the stabilizing and catalytic properties of enzyme substrate binding protein pockets. One such system is the Fe4SP@HKUST-1 metal organic framework (MOF) system, also known as MOMzyme-1, in which Fe(III)tetrakis(4-sulphonatophenyl)porphyrin (Fe4SP) is encapsulated within the cuboctahedral cavities of the HKUST-1 MOF. Within this system the Fe4SP heme active site is encapsulated in a pseudo protein pocket within the MOF. Here, the ability of the Fe4SP@HKUST-1 to catalyze the tandem epoxidation of olefins followed by selective alcoholysis is examined. It is observed that encapsulation of Fe4SP within the MOF framework significantly enhances the turnover number (TON) of peroxide-driven epoxidation of styrene while greatly reducing metalloporphyrin degradation and maintaining stereoisomer selectivity. The Fe4SP@HKUST-1 catalyzes both the olefin epoxidation and the subsequent ring opening through the addition of CH3OH. The epoxidation of styrene occurs through the hydrogen peroxide generated high valent Fe(IV) = O of the encapsulated Fe4SP while the corresponding ring opening and methanolysis takes place at the Cu metallo building blocks of the HKUST-1 framework. These results provide a framework through which to develop a more extensive library of bio-inspired heme-based MOF catalysts.

Stepwise Amplification of Circularly Polarized Luminescence in Chiral Metal Cluster Ensembles.

Chiral metal-organic frameworks(MOFs)are usually endowed by chiral linkers and/or guests. The strategy using chiral secondary building units in MOFsfor solving the trade-off of circularly polarized luminescence (CPL)-active materials, high photoluminescence quantum yields (PLQYs) and high dissymmetry factors (|glum |) has not been demonstrated. This work directionally assembles predesigned chiral silver clusters with ACQ linkers through reticular chemistry. The nanoscale chirality of the cluster transmits through MOF's framework, where the linkers are arranged in a quasi-parallel manner and are efficiently isolated and rigidified. Consequently, this backbone of chiral cluster-based MOFs demonstrates superb CPL, high PLQYs of 50.3%, and |glum | of 1.2 × 10-2 . Crystallographic analyses and DFT calculations show the quasi-parallel arrangement manners of emitting linkers leading to a large angle between the electric and magnetic transition dipole moments, boosting CPL response. As compared, an ion-pair-direct assembly without interactions between linkers induces one-ninth |glum | and one-sixth PLQY values, further highlighting the merits of directional arrangement in reticular nets. In addition, a prototype CPL switching fabricated by a chiral framework is controlled through alternating ultraviolet and visible light. This work is expected to inspire the development of reticular chemistry for high-performance chiroptical materials.

Understanding hydrogen adsorption performance of lithium-doped MIL-101(Cr) by molecular simulations: Effects of lithium distribution

Metal-organic frameworks (MOFs) have been recognized as one of the most compelling physical adsorption hydrogen storage materials owing to their ultrahigh surface area and excellent hydrogen adsorption performance. In order to further improve their hydrogen adsorption performance, lithium doping is an effective approach to increase the number of hydrogen adsorption sites as well as enhance the interaction strength towards hydrogen molecules according to grand canonical Monte Carlo(GCMC) simulations. However, in previous simulation studies, lithium ions were commonly assumed to be randomly distributed in MOF frameworks. In fact, the lithium-doped MOFs were prepared by immersing MOFs in a lithium salt solution and then drying them under high temperatures, in which the distribution of Li+ in MOF frameworks is elusive. In this work, the lithium-doped MIL-101 models (i.e., Immersion model) with varying lithium contents were constructed according to experimental operation and their hydrogen adsorption performance from GCMC simulations was also investigated in comparison with the equivalent models with randomly distributed lithium ions (i.e., Random model). It is found that in contrast to the uniform distribution of lithium ions in Random model, the accumulation of lithium ions was inspected in Immersion models especially at high loadings, leading to the reduced pore size. On the contrary, the hydrogen adsorption capacities of Immersion models are significantly improved owing to the enhanced interaction strength with hydrogen molecules resulting from the reduced pore size and the strengthened charged-induced dipole interaction.

Reticular Design of Precise Linker Installation into a Zirconium Metal–Organic Framework to Reinforce Hydrolytic Stability

Reticular chemistry allows for the rational assembly of metal-organic frameworks (MOFs) with designed structures and desirable functionalities for advanced applications. However, it remains challenging to construct multi-component MOFs with unprecedented complexity and control through insertion of secondary or ternary linkers. Herein, we demonstrate that a Zr-based MOF, NU-600 with a (4,6)-connected she topology, has been judiciously selected to employ a linker installation strategy to precisely insert two linear linkers with different lengths into two crystallographically distinct pockets in a one-pot, de novo reaction. We reveal that the hydrolytic stability of these linker-inserted MOFs can be remarkably reinforced by increasing the Zr6 node connectivity, while maintaining comparable water uptake capacity and pore-filling pressure as the pristine NU-600. Furthermore, introducing hydrophilic -OH groups into the linear linker backbones to construct multivariate MOFs can effectively shift the pore-filling step to lower partial pressures. This methodology demonstrates a powerful strategy to reinforce the structural stability of other MOF frameworks by increasing the connectivity of metal nodes, capable of encouraging developments in fundamental sciences and practical applications.

Ln-MOF Based Ratiometric Luminescent Sensor for the Detection of Potential COVID-19 Drugs.

Countless people have been affected by the COVID-19 pandemic on a global scale. Favipiravir, has shown potential as an effective drug for SARS-CoV-2, attracting scientists' attention. However, overuse of Favipiravir easily leads to serious side effects, requiring real-time monitoring in body fluids. Given this, a new lanthanide metal-organic framework (MOF) was prepared under solvothermal conditions from either Eu (Eu-MOF or (1)) or Tb (Tb-MOF or (2)) using the highly delocalized imidazoledicarboxylic acid linker H2 L (H2 L=5-(4-(imidazol-1-yl) phenyl) isophthalic acid) and could be successfully applied to selective optical detection of Favipiravir. In this MOF framework, the organic linker H2 L provides a high excitation energy transfer efficiency that can sensitize luminescence in lanthanides. In addition, through deliberate tuning of Eu/Tb molar ratio and reaction concentration in the lanthanide framework, ratiometric recyclable luminescent Eux Tb1-x -MOF nanoparticles with open metal sites have been constructed, which present a high detection sensitivity (Ksv =1×107 [M-1 ], detection limit is 4.63 nM) for Favipiravir. The detection mechanism is discussed with the help of Density Functional Theory (DFT) calculations that sheds light over the selective sensing of Favipiravir over other related COVID-19 drug candidates. Finally, to explore the practical application of Favipiravir sensing, MOF based thin films have been used for visual detection of Favipiravir and recycled 5 times.