3D Metal-organic Framework Research Articles

A Highly Conducting Tetrathiafulvalene-Tetracarboxylate Based Dysprosium(III) 2D Metal-Organic Framework with Single Molecule Magnet Behaviour

The synthesis and whole characterization by a multitechnique approach of an unprecedented dysprosium (III) 2D metal organic framework (MOF), involving the redox-active tetrathiafulvalene (TTF)-based linker TTF-tetracarboxylate (TTF-TC), are herein reported....

Realizing altermagnetism in two-dimensional metal-organic framework semiconductors with electric-field-controlled anisotropic spin current.

Altermagnets exhibit momentum-dependent spin-splitting in a collinear antiferromagnetic order due to their peculiar crystallographic and magnetic symmetry, resulting in the creation of spin currents with light elements. Here, we report two two-dimensional (2D) metal-organic framework (MOF) semiconductors, M(pyz)2 (M = Ca and Sr, pyz = pyrazine), which exhibit both altermagnetism and topological nodal point and line by using first-principles calculations and group theory. The altermagnetic 2D MOFs exhibit unconventional spin-splitting and macroscopic zero magnetization caused by 4-fold rotation in crystalline real space and 2-fold rotation in spin space, leading to the generation and control of anisotropic spin currents when an in-plane electric field ( E ) is applied. In particular, pure spin current with the spin Hall effect occurs when E is applied along the angular bisector of the two spin arrangements. Our work indicates the existence of altermagnetic MOF systems and a universal approach to generate electric-field-controlled spin currents for potential applications in antiferromagnetic spintronics.

2D ZIF-L(Zn) for Hybrid Copolymerization of Methyl Methacrylate and ε-Caprolactone under Solvent-free Medium

Herein, we report the hybrid copolymerization of methyl methacrylate (MMA) and ε-caprolactone (CL). 2D metal-organic frameworks, ZIF-L as a robust polymerization catalyst, can catalyze this hybrid copolymerization. Though these monomers differ from each other in structure and activity, different characterization techniques (1H-NMR, 13C-NMR, GPC, DSC, fractional precipitation techniques) confirm that they form biodegradable block copolymer PMMA-b-PCL with high molecular weight (1190 kg/mol). Also, PXRD and SEM results of the recovered ZIF-L reveal that the catalyst ZIF-L is remarkably stable even after a long-time polymerization reaction with no significant loss in activity.

Triazole-rich 3D metal-organic framework incorporated solid electrolytes for superior proton conductivity and durability in fuel cells.

Insufficient proton conductivity and oxidative stability of sulfonated hydrocarbons hinder their applicability as proton exchange membrane electrolytes in fuel cells. In this regard, fabrication of proton conducting mixed-matrix membranes (PC-MMMs) can be a superior approach to obtain desirable properties. In this work, a triazole ligand (1H-1,2,4 triazole) was coordinated to a zinc metal node to create a 3D metal-organic framework (MOF) and incorporated as an additive in a sulfonated poly(ether ether ketone) matrix at 1, 3, and 5 weight percentage to fabricate PC-MMMs by the casting process. Several characterization tools such as electrochemical impedance spectroscopy, Fourier transform infrared spectroscopy and scanning electron microscopy were used to characterise these membranes and study their potential application as electrolyte(s) in PEMFCs (proton exchange membrane fuel cells). Membranes were also tested for water uptake, ion-exchange capacity and oxidative stability in Fenton's reagent. The performance of the polymeric composite membrane containing a 3 wt% MOF was then assessed in a H2/O2 single cell as it demonstrated the highest proton conductivity of 0.04 S cm-1 among all the compositions and a maximum current density of 1191 mA cm-2. The membrane was also subjected to an OCV hold test for 12 hours to study the chemical durability over a period of time. This report establishes that the inclusion of a triazole based MOF enhances the proton conductivity, performance, and thermal and chemical durability of composite membranes which can be considered as a promising electrolyte material at intermediate temperatures after a proper optimisation of different cell parameters.

Effect of metal-ligand interactions on magnetic characteristics of two-dimensional Kagome structured perthiolated coronene (PTC) metal-organic frameworks (MOFs).

In recent years, the potential applications of two-dimensional (2D) metal-organic framework (MOF) materials in fields like spintronics have drawn increasing attention. Inspired by the successful synthesis of a perthiolated coronene (PTC)-Fe MOF structure, this study explores the fine-tuning of its electronic and magnetic structure by substituting Fe elements with various transition metals. Our calculations demonstrate a substantial increase in the Curie temperature (Tc) by a factor of 5 for Co and 10 for Mn when replacing Fe. This enhancement is attributed to the elevated electron density near the Fermi level, facilitating the generation of additional itinerant electrons crucial for the Ruderman-Kittel-Kasuya-Yosida (RKKY) exchange mechanism. However, substituting Fe with V, Cr, Ni, and Cu leads to a loss of ferromagnetic ground state. Our work enhances the understanding of the electronic and magnetic behavior of the 2D PTC-TM (transition metal) MOF family, and provides a promising avenue for engineering 2D magnetic MOF systems.

Two-dimensional multifunctional metal-organic frameworks with large in-plane negative Poisson ratios and photocatalytic water splitting properties.

Auxetic materials with multifunctional properties are highly sought after for application in modern nano-devices. However, the majority of reported inorganic auxetic materials exhibit low negative Poisson's ratios (NPR), poor flexibility, and limited functionality. In this study, we employ density-functional-theory (DFT) first-principles simulations to design a series of two-dimensional (2D) metal-organic frameworks (MOFs) M2C4X4 (M = Cu, Ag, Au; X = O, S, NCN) that display intriguing auxetic behavior, superior flexibility and appropriate photocatalytic water-splitting properties. These M2C4X4 MOFs are assembled from carbon tetragon motifs and exist in both cis- and trans-isomer forms, with the NPR ranging from -0.17 to -0.90. Notably, trans-Cu2C4(NCN)4 exhibits a high NPR of -0.90, while cis-Cu2C4(NCN)4 achieves an NPR of -0.67. Both isomers demonstrate excellent flexibility, characterized by ultra-low Young's modulus and high fracture strengths. Furthermore, their direct band gaps, strong light-harvesting capabilities, and long excited-state lifetimes make them promising candidates for the photocatalytic oxygen evolution reaction in water. These results provide a viable strategy for the design and synthesis of novel optoelectronic multifunctional materials.

Carbonic anhydrase-mimicking metal-organic frameworks built from amino acid and cadmium ions.

Built from L-histidine amino acid ligand and cadmium ions, two new 3D chiral metal-organic frameworks, [α-Cd(HIS)] (1) and [β-Cd(HIS)] (2), which contain metal-histidine bonds mimicking the structure features of carbonic anhydrase, demonstrate interesting properties of catalyzing the hydrolysis of p-nitrophenylacetate (p-NPA) to para-nitrophenol (p-NP).

Bidirectional photomagnetism, exciplex fluorescence and dielectric anomalies in a spin crossover Hofmann-type coordination polymer.

Stepped spin crossover (SCO) complexes with three or more spin states have promising applications in high-order data storage, multi-switches and multi-sensors. Further synergy with other functionalities, such as luminescence and dielectric properties, will provide a good chance to develop novel multifunctional SCO materials. Here, a bent pillar ligand and luminescent pyrene guest are integrated into a three-dimensional (3D) Hofmann-type metal-organic framework (MOF) [Fe(dpoda){Au(CN)2}2]·pyrene (dpoda = 2,5-di-(pyridyl)-1,3,4-oxadiazole). The magnetic data show an incomplete and two-step SCO behavior with the sequence of 1 ↔ 1/2 ↔ 1/4. The rare bi-directional light-induced excited spin-state trapping (LIESST) effect and light-induced stepped thermal relaxation after LIESST are observed. The pyrene guests interact with dpoda ligands via offset face-to-face π⋯π interactions to form intermolecular exciplex emissions. The competition between thermal quenching and stepped SCO properties results in a complicated and stepped exciplex fluorescence. Moreover, the stepped dielectric property with higher dielectric permittivity at lower temperature may be related to the more frustrated octahedral distortion parameters in the intermediate spin states. Hence, a 3D Hofmann-type MOF with bent pillar ligands and fluorescent guests illustrates an effective way for the development of multifunctional switching materials.

Pyridine-induced caused structural reconfiguration forming ultrathin 2D metal–organic frameworks for the oxygen evolution reaction

2D Co MOF-Py3 is synthesized by a bottom-up structural reconfiguration strategy by using pyridine for the oxygen evolution reaction.

2D metal–organic framework derived ultra-thin nitrogen-doped oxygen rich porous carbon nanosheets for zinc-ion hybrid supercapacitors

2D MOF derived ultra-thin carbon nanosheets with high reactivity, super-hydrophilicity and hierarchical porosity are prepared. The corresponding Zn-ion hybrid supercapacitor delivers exceptional energy storage capability with long cycling stability.

Ozonolysis–oxidation-driven top-down strategy for the target preparation of ultrathin 2D metal–organic framework monolayers

A novel chemical exfoliation method is developed for the target preparation of 2D MOF monolayers from the 3D pillar-layered MOFs.

Ultrathin MOF nanosheets and their mixed-matrix membranes for ammonia and aliphatic amine sensing in water.

Ultrathin 2D metal-organic frameworks (MOFs) exhibit a myriad of unparalleled properties, rendering them extensively applicable across various fields. Despite this, developing a 2D MOF sensor for detecting hazardous amines in water remains a formidable challenge. To address this issue, we synthesized Ni-btc MOF ultrathin nanosheets with a thickness of approximately 4.15 nm for the detection of amines in water. These nanosheets demonstrated a notable "turn-on" fluorescence response in the presence of ammonia and aliphatic amines. The detection limit for aliphatic amines ranged from 297 to 424 nM, while for ammonia, it reached an impressive low limit of around 42 nM, which is an excellent value compared to other reported MOFs for ammonia sensing in water. Density functional theory calculations elucidated the mechanism underlying fluorescence enhancement. Additionally, a mixed matrix membrane based on MOF nanosheets was fabricated for real-time sensing that exhibits an immediate color change in the presence of ammonia and aliphatic amines.

2D metal-organic frameworks bearing butterfly-shaped metal-bis(dithiolene) linkers from dithiol-functionalized benzenedicarboxylic acid.

An assembly between 1,4-dicarboxylbenzene-2,3-dithiol (H2dcbdt) and different transition metal ions successfully produced 2D metal-organic frameworks (M-dcbdt, M = Ni, Co or Fe) composed of unprecedented butterfly-shaped metal-bis(dithiolene) (MS4) linkers in one-pot fashion. Such strategy provides easier access to the [MS4]-rich network and lowers the prerequisite to explore their applications.

Utilisation of carbon dioxide and nitrate for urea electrosynthesis with a Cu-based metal-organic framework.

It is important and challenging to utilise CO2 and NO3- as a feedstock for electrosynthesis of urea. Herein, we reported a stable 2D metal-organic framework (MOF) Cu-HATNA, possessing planar CuO4 active sites, as an efficient electrocatalyst for coupling CO2 and NO3- into urea, achieving a high yield rate of 1.46 g h-1 gcat-1 with a current density of 44.2 mA cm-1 at -0.6 V vs. RHE. This performance surpasses most of the previously reported catalysts, revealing the great prospects of MOFs in sustainable urea synthesis.

Optimizing Porous Metal-Organic Layers for Stable Zinc Anodes.

Aqueous zinc-ion batteries (ZIBs) have been considered as alternative stationary energy storage systems, but the dendrite and corrosion issues of Zn anodes hinder their practical applications. Here we report a series of two-dimensional (2D) metal-organic frameworks (MOFs) with Zr12 clusters, which act as artificial solid electrolyte interphase (SEI) layers to prevent dendrites and corrosion of Zn anodes. The Zr12-based 2D MOF layers were formed by incubating 3D layer-pillared Zr-MOFs in ZnSO4 aqueous electrolytes, which replaced the pillar ligands with terminal SO42-. Furthermore, the pore sizes of Zr12-based 2D MOF layers were systematically tuned, leading to optimized Zn2+ conduction properties and protective performance for Zn anodes. In contrast to the traditional 2D-MOFs with Zr6 clusters, Zr12-based 2D MOF layers as artificial SEI significantly reduced the polarization and increased the stability of Zn anodes in MOF@Zn||MOF@Zn symmetric cells and MOF@Zn||MnO2 full cells. In situ experiments and DFT computations reveal that the enhanced cell performance is attributed to the unique Zr12-based layered structure with intrinsic pores to allow fast Zn2+ diffusion, surface Zr-SO4 zincophilic sites to induce uniform Zn deposition, and inhibited hydrogen evolution by 2D MOF Zr12 layers.

Interface-Engineered 2D Heterojunction with Photoelectric Dual Gain: Mxene@MOF-Enhanced SPR Spectroscopy for Direct Sensing of Exosomes.

MXene is widely used in the construction of optoelectronic interfaces due to its excellent properties. However, the hydrophilicity and metastable surface of MXene lead to its oxidation behavior, resulting in the degradation of its various properties, which seriously limits its practical application. In this work, a 2D metal-organic framework (2D MOF) with matching 2D morphology, excellent stability performance, and outstanding optoelectronic performance is grown in situ on the MXene surface through heterojunction engineering to suppress the direct contact between reactive molecules and the inner layer material without affecting the original advantages of MXene. The photoelectric dual gain MXene@MOF heterojunction is confirmed. As a photoelectric material, its properties are highly suitable for the demand of interface sensitization layer materials of surface plasmon resonance (SPR). Therefore, using SPR as a platform for the application of this interface material, the performance of MXene@MOF and its potential mechanism to enhance SPR are analyzed in depth using experiments combined with simulation calculations (FDTD/DFT). Finally, the MXene@MOF/peptides-SPR sensor is constructed for rapid and sensitive detection of the cancer marker exosomes to explore its potential in practical applications. This work offers a forward-looking strategy for the design of interface materials with excellent photoelectric performance.

Porphyrin-Based Two-Dimensional Metal-Organic framework nanosheets for efficient photocatalytic CO2 transformation

2D metal − organic framework (MOF) nanosheets have been demonstrated to exhibit excellent properties and prospects in various aspects, especially in photocatalysis. However, the design and direct preparation of 2D MOF photocatalyst is highly desirable but still challenging. Herein, a novel 2D porphyrin-based MOF Fe-DBP(Co), which is assembled by dicarboxylic porphyrin ligands and the unprecedented undecametallic ferric-oxo clusters, is designed and developed. The unique nanosheet morphology and assembled layered structure endows the photocatalyst with higher electron-hole separation efficiency and longer photogenerated carrier lifetime compared to the analogous MOFs. Consequently, Fe-DBP(Co) exhibits strikingly excellent and stable photocatalytic performance in CO2 cycloaddition, and the reaction rate of 103.2 mmol∙g−1∙h−1 is among the state-of-the-art cases for MOF-photocatalyzed CO2 cycloaddition. The underlying mechanism investigation suggested that photogenerated electrons transferred from CoDBP ligands to the Fe clusters, and the abundant electrons and holes promoted the generation of Fe(II) and Co(III) respectively, leading to excellent catalytic performance. This work proposes a new strategy to design and develop efficient MOF photocatalysts for photocatalytic transformation of CO2.

Fabrication of Carboxylate-Functionalized 2D MOF Nanosheet with Caged Cavity for Efficient and Selective Extraction of Uranium from Aqueous Solution.

The efficient removal of radioactive uranium from aqueous solution is of great significance for the safe and sustainable development of nuclear power. An ultrathin 2D metal-organic framework (MOF) nanosheet with cavity structures was elaborately fabricated based on a calix[4]arene ligand. Incorporating the permanent cavity structures on MOF nanosheet can fully utilize its structural characteristics of largely exposed surface area and accessible adsorption sites in pollutant removal, achieving ultrafast adsorption kinetics, and the functionalized cavity structure would endow the MOF nanosheets with the ability to achieve preconcentration and extraction of uranium from aqueous solution, affording ultrahigh removal efficiency even in ultra-low concentrations. Thus, more than 97% uranium can be removed from the concentration range of 50-500µgL-1 within 5min. Moreover, the 2D nano-material exhibits ultra-high anti-interference ability, which can efficiently remove uranium from groundwater and seawater. The adsorption mechanism was investigated by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR) analysis, and density functional theory (DFT) calculations, which revealed that the cavity structure plays an important role in uranium capture. This study not only realizes highly efficient uranium removal from aqueous solution but also opens the door to achieving ultrathin MOF nanosheets with cavity structures, which will greatly expand the applications of MOF nanosheets.

2D MOF based-heterostructure with hierarchical architecture as antibacterial wound dressing

Bacterial infections pose a huge threat to human health due to the inevitable emergency of drug resistance. Metal-organic frameworks (MOFs) consisting of metal ions and organic linkers, as emerging efficient antibacterial material, have the merits of structural flexibility and adjustable physicochemical property. With assistance of photosensitive agents as organic linkers, MOFs have great potential in antibacterial application through photocatalytic therapy by the generation of reactive oxygen species (ROS). However, the limited light use efficiency and short lifespan of ROS are two obstacles for their applications. Inspired by the semiconductor heterostructure in photocatalysis, we rationally design and precisely synthesize MOFs based heterostructures, in which the TiO2 nanoclusters are filled into the pores of Cu-TCPP nanosheets (i.e. TiO2 NCs@Cu-TCPP HSs). And the composite materials possess three-dimensional (3D) hierarchical architectures, which have advantages of large surface area, excellent light-absorbing ability and photocatalytic efficiency. Significantly, this novel material displays >99.99 % antibacterial efficiency against E. coli and S. aureus within 30 min and preserves the excellent antibacterial ability during reusing three times, which is superior to recently reported photocatalystic-based antibacterial materials. Our study provides new insights into the energy band engineering for enhanced antibacterial performance, paving a way for designing advanced clinical wound dressings.

Effect of the Metal Node and Synthesis Method of Triphenylene Based MOFs on the Performance of Li-Ion Batteries

The development of efficient energy storage systems is considered crucial to achieve carbon-free energy, being the electrochemical energy storage technologies especially relevant for mobile devices and the transportation sector. In particular, lithium ion batteries (LIBs) are currently the most used technology in these applications because of their high energy and power density, long cycle life, and competitive cost 1. Due to these properties, the future lithium-based battery market predictions forecast a dramatic increase in demand of battery energy of more than an order of magnitude 2. However, since LIBs commercialization in 1991 the advances have been incremental and the component electrode and electrolyte materials still remain the same with improved engineering modifications. In this context, the European Commission calls for transformative battery research and setting the development of the competitive battery industry in Europe.New materials for electrodes can provide new properties and mechanisms of energy storage than commonly used inorganic materials. For example, metal-organic framework (MOF) materials composed by inorganic nodes (clusters or metal ions) connected by organic ligands provide coordination networks extended in either two or three dimensions, and high porosity 3. Owing to their rational design, structural diversity and tunable physical and chemical properties (including surface area, pore size and functionalities, etc.) MOFs have been intensively studied as advanced functional materials for a large variety of applications 4, including energy storage 5.In the present work we perform a systematic study of MOFs based on a triphenylene ligand, HHTP (2,3,6,7,10,11-hexahydroxytriphenylene) varying the metal node. Triphenylene based MOFs are characterized by high electronic conductivity6 due to the π-d conjugation in the ab plane, behaving as 2D graphene analogues. Besides, space conductivity is observed thanks to the interlayer π-π stacking in the c direction 7. Here two methods of preparation are evaluated, bulk synthesis and electrode preparation by doctor-blade deposition and in-situ synthesis of the 2D MOF at the air-liquid interface and posterior transference to the battery substrate8. The MOF powders were characterized by XRD diffraction and IR and XPS spectroscopies, techniques used when possible to characterize the obtained films. The performance of the fabricated lithium half-cell batteries has been analyzed electrochemically to have basic information and the potential of the films as protective layers in anode-less batteries. The electrochemical characterization includes galvanostatic charging-discharging, platting-striping plots at different charge rate, electrochemical impedance spectroscopy (EIS), and XPS analysis after cycling. The results show that the energy density of the electrode can be duplicated depending on the metal node, presumably by a change of electrochemical energy storage. Also the thin films of these MOFs are promising candidates as protective layers with the formation of a more stable solid electrolyte interface (SEI). References M. Armand, P. Axmann, D. Bresser, M. Copley, K. Edström, C. Ekberg, D. Guyomard, B. Lestriez, P. Novák and M. Petranikova, Journal of Power Sources, 2020, 479, 228708. J. Monassen, G. Hodes and D. Cahen, Journal of The Electrochemical Society, 1977, 124, 532-534. S. R. Batten, N. R. Champness, X.-M. Chen, J. Garcia-Martinez, S. Kitagawa, L. Öhrström, M. O’Keeffe, M. P. Suh and J. Reedijk, Pure Appl. Chem., 2013, 85, 1715-1724. R. Freund, O. Zaremba, G. Arnauts, R. Ameloot, G. Skorupskii, M. Dincă, A. Bavykina, J. Gascon, A. Ejsmont, J. Goscianska and others, Angewandte Chemie International Edition, 2021, 60, 23975-24001. B. Zhu, D. Wen, Z. Liang and R. Zou, Coord. Chem. Rev., 2021, 446, 214119. T. Chen, J.-H. Dou, L. Yang, C. Sun, N. J. Libretto, G. Skorupskii, J. T. Miller and M. Dincă, J. Am. Chem. Soc., 2020, 142, 12367-12373. G. Skorupskii, B. A. Trump, T. W. Kasel, C. M. Brown, C. H. Hendon and M. Dincă, Nat. Chem., 2019, 12, 131-136. I. Ciria-Ramos, I. Tejedor, L. Caparros, B. Doñagueda, O. Lacruz, A. Urtizberea, O. Roubeau, Gascón, I. and M. Haro, in revision, 2023. Acknowledgements The authors acknowledge the DGA/fondos FEDER (construyendo Europa desde Aragón) for funding the research group Platon (E31_20R) and the project LMP71_21. M.H. acknowledges the funding support from MCIN/AEI/10.13039/501100011033 for the Ramón y Cajal fellowship (RYC-2018-025222-I).