Metal–organic framework-derived porous materials for catalysis

Metal-Organic Frameworks and Their Derived Materials: Emerging Catalysts for a Sulfate Radicals-Based Advanced Oxidation Process in Water Purification

With the ever-growing environmental issues, sulfate radical (SO₄^•- )-based advanced oxidation processes (SR-AOPs) have been attracting widespread attention due to their high selectivity and oxidative potential in water purification. Among various methods generating SO₄^•- , employing heterogeneous catalysts for activation of peroxymonosulfate or persulfate has been demonstrated as an effective strategy. Therefore, the future advances of SR-AOPs depend on the development of adequate catalysts with high activity and stability. Metal-organic frameworks (MOFs) with large surface area, ultrahigh porosity, and diversity of material design have been extensively used in heterogeneous catalysts, and more recently, enormous effort has been made to utilize MOFs-based materials for SR-AOPs applications. In this work, the state-of-the-art research on pristine MOFs, MOFs composites, and their derivatives, such as oxides, metal/carbon hybrids, and carbon materials for SR-AOPs, is summarized. The mechanisms, including radical and nonradical pathways, are also detailed in the discussion. This work will hopefully promote the future development of MOFs-based materials toward SR-AOPs applications.

Metal-Organic Framework MIL-53(Fe) as an Adsorbent for Ibuprofen Drug Removal from Aqueous Solutions: Response Surface Modeling and Optimization

Ibuprofen contamination from water sources has been increasingly alarming due to its environmentally accumulative retention; however, the strategies for ibuprofen-containing water treatment are still an enormous challenge. Herein, we described the utilization of metal-organic frameworks MIL-53(Fe) (MIL = Materials of Institute Lavoisier) for the adsorption of ibuprofen in synthetic solution. Firstly, the MIL-53(Fe) was solvothemally synthesized and then characterized using the X-ray diffraction and Fourier-transform infrared spectroscopy techniques. The optimization of ibuprofen adsorption over MIL-53(Fe) was performed with three independent variables including ibuprofen concentration (1.6–18.4 mg/L), adsorbent dosage (0.16–1.84 g/L), and pH (2.6–9.4) according to the experimental design from response surface methodology. Under the optimized conditions, more than 80% of ibuprofen could be eliminated from water, indicating the promising potential of the MIL-53(Fe) material for treatment of this drug. Kinetic and isotherm models also were used to elucidate the chemisorption and monolayer behavior mechanisms of ibuprofen over MIL-53(Fe).

Tunable Synthesis of Mesoporous Carbons from Fe₃O(BDC)₃ for Chloramphenicol Antibiotic Remediation

Chloramphenicol (CAP) is commonly employed in veterinary clinics, but illegal and uncontrollable consumption can result in its potential contamination in environmental soil, and aquatic matrix, and thereby, regenerating microbial resistance, and antibiotic-resistant genes. Adsorption by efficient, and recyclable adsorbents such as mesoporous carbons (MPCs) is commonly regarded as a "green and sustainable" approach. Herein, the MPCs were facilely synthesized via the pyrolysis of the metal⁻organic framework Fe₃O(BDC)₃ with calcination temperatures (x °C) between 600 and 900 °C under nitrogen atmosphere. The characterization results pointed out mesoporous carbon matrix (MPC700) coating zero-valent iron particles with high surface area (~225 m²/g). Also, significant investigations including fabrication condition, CAP concentration, effect of pH, dosage, and ionic strength on the absorptive removal of CAP were systematically studied. The optimal conditions consisted of pH = 6, concentration 10 mg/L and dose 0.5 g/L for the highest chloramphenicol removal efficiency at nearly 100% after 4 h. Furthermore, the nonlinear kinetic and isotherm adsorption studies revealed the monolayer adsorption behavior of CAP onto MPC700 and Fe₃O(BDC)₃ materials via chemisorption, while the thermodynamic studies implied that the adsorption of CAP was a spontaneous process. Finally, adsorption mechanism including H-bonding, electrostatic attraction, π⁻π interaction, and metal⁻bridging interaction was proposed to elucidate how chloramphenicol molecules were adsorbed on the surface of materials. With excellent maximum adsorption capacity (96.3 mg/g), high stability, and good recyclability (4 cycles), the MPC700 nanocomposite could be utilized as a promising alternative for decontamination of chloramphenicol antibiotic from wastewater.

Controlled Manipulation of Metal-Organic Framework Layers to Nanometer Precision Inside Large Mesochannels of Ordered Mesoporous Silica for Enhanced Removal of Bisphenol A from Water

Considerable attention has been paid on the design of hierarchical porous metal-organic framework (MOF) composites, which not only enhances the performance but also broadens the applications of MOFs. So far, controlled manipulation of nanometer-thick MOF layers in ordered mesochannels, while retaining their respective intrinsic properties, is still a main challenge because of the difficulty of growing MOFs in confined space. Herein, using a step-by-step coordination method, the formation of a hierarchical micro-mesoporous hybrid with a wall (channel wall and coating layer) thickness of up to 8.0 nm and open pore size down to 7.7 nm has been achieved based on large mesoporous SBA-15, and the wall thickness with nanometer precision can be controlled by adjusting the growth cycles of zeolite imidazolate framework-8 (ZIF-8) coating layers. Compared to pure ZIF-8, the obtained ZIF-8@SBA-15 composites showed more than 2-fold enhancement in adsorption capacity and approximately 20-fold improvement in the adsorption rate constant for bisphenol A in water, which could be ascribed to the synergistic effects of the high adsorption ability from ZIF-8 and the fast diffusion property from SBA-15. More importantly, the degraded ZIF-8@SBA-15 composite can be completely restored by a simple immersion into 2-methylimidazole solution. The easy restorability and good reusability further enable ZIF-8@SBA-15 as a promising adsorbent for effectively removing organic contaminants from water.

MOF-derived Ni@NC catalyst: synthesis, characterization, and application in one-pot hydrogenation and reductive amination

MOF-derived Ni@NC is prepared and used as highly selective catalyst for one-pot hydrogenation and reductive amination.

One-step MOF-derived Co/Co9S8 nanoparticles embedded in nitrogen, sulfur and oxygen ternary-doped porous carbon: an efficient electrocatalyst for overall water splitting

Co/Co₉S₈ nanoparticles encapsulated in a N, S, and O ternary-doped carbon matrix were synthesized utilizing a Co-NSOMOF as a single precursor, and they exhibited excellent bifunctional electrocatalytic activity for the OER and HER.

Carbon capture and conversion using metal–organic frameworks and MOF-based materials

This review summarizes recent advances and highlights the structure–property relationship on metal–organic framework-based materials for carbon dioxide capture and conversion.

Molecular tectonics: homochiral 1D and 2D cadmium based coordination networks

By combining enantiomerically pure tectons with Cd(NO₃)₂, a series of six new homochiral luminescent coordination networks are formed. The dimensionality and crystal packing of the latter are modulated by both the nature of the chiral side chains and the crystallization solvents.

Unraveling the relationship between the morphologies of metal–organic frameworks and the properties of their derived carbon materials

The effects of the morphologies of MOF precursors on the properties of their derived carbonaceous materials are systematically studied.

Cd(ii) coordination polymers constructed from bis(pyridyl) ligands with an asymmetric spacer in chelating mode and diverse organic dicarboxylates: syntheses, structural evolutions and properties

Thirteen Cd(ii) complexes with diverse chain, (4,4), (6,3), (6³), (6⁵·8), 2-periodic (6,3) layers, and diverse 3D vma, irl, cds, eca nets have been synthesized.

Photo-induced electron transfer in a metal–organic framework: a new approach towards a highly sensitive luminescent probe for Fe3+

By utilizing the d-PET process between ligands 4,4′-bimbp and H₂pta in a Co-based mixed-ligand MOF, ZJU-109, a fluorescent turn-on sensor for Fe³⁺ with a detection limit as low as 0.053 μM has been demonstrated.

Fabrication of Fe3O4@UiO-66-SO3H core–shell functional adsorbents for highly selective and efficient removal of organic dyes

A novel magnetic nanocomposite with a core–shell structure was first synthesized and employed as an adsorbent to selectively remove methylene blue.

Synthesis, structure, fluorescence and electrochemical properties of a new Zn(ii)–organic framework constructed by a tricarboxylic acid ligand

A new efficient fluorescent sensor [Zn₃(L)(HL)(OH)(H₂O)₃]·H₂O (1) for detecting Cr₂O₇²⁻ anions has been synthesized. Moreover, compound 1 has been calcined to prepare a new electrocatalyst R-C@800 for HER.

A two-dimensional multi-shelled metal–organic framework and its derived bimetallic N-doped porous carbon for electrocatalytic oxygen reduction

We report a multi-shelled two-dimensional metal–organic framework (MOF), which is transferred to a Co/Ni-embedded bimetallic N-doped porous carbon.

Metal–organic framework-derived heterojunctions as nanocatalysts for photocatalytic hydrogen production

A summary of using the pore chemistry or surface chemistry of MOFs to construct heterojunction nanocatalysts for photocatalytic hydrogen production.

Metal Organic Frameworks Based Materials for Heterogeneous Photocatalysis

The increase in environmental pollution due to the excessive use of fossil fuels has prompted the development of alternative and sustainable energy sources. As an abundant and sustainable energy, solar energy represents the most attractive and promising clean energy source for replacing fossil fuels. Metal organic frameworks (MOFs) are easily constructed and can be tailored towards favorable photocatalytic properties in pollution degradation, organic transformations, CO₂ reduction and water splitting. In this review, we first summarize the different roles of MOF materials in the photoredox chemical systems. Then, the typical applications of MOF materials in heterogeneous photocatalysis are discussed in detail. Finally, the challenges and opportunities in this promising field are evaluated.

Gas-solid aldol condensation reaction in confined space of metal organic framework for formaldehyde detection

Herein, a gas-sensitive functional nanomaterial was constructed by confining Tb(acac)₃(H₂O)₂ (acac = acetylacetone) in the space of the metal organic framework ZIF-8. This functional nanomaterial can realize a gas-solid state aldol condensation reaction, even at room temperature and without the use of a catalyst. In the reaction process, formaldehyde (FA) gas molecules can invalidate the antenna effect of the acac ligands, and it can therefore act as an ultrasensitive FA gas remover and detector (limit of detection value = 49 ppb).

Paving Metal-Organic Frameworks with Upconversion Nanoparticles via Self-Assembly

The combination of metal-organic frameworks (MOFs) and luminescent nanomaterials with upconversion characteristics could enable the development of new nanomaterials and applications in information security, optical sensing, and theranostics. However, currently available methods are not ideally suitable for fabricating composites of MOF and upconversion nanomaterial, and incorporating upconversion nanomaterials with MOFs in a controllable manner remains challenging. Here, we demonstrate an in situ self-assembly route to the nanocomposites in which MOFs are homogeneously paved with upconversion nanoparticles. Without additional assistance, this strategy, mainly driven by electrostatic interactions, can be used to incorporate different upconversion nanoparticles with diverse MOFs. The as-synthesized composites can be further used to construct composites with unique structures, such as MOF@upconversion nanoparticles@MOF sandwiched nanocomposites, and would be useful for applications including luminescence-monitored drug delivery, anticounterfeiting, and photodynamic therapy. These findings should shed light on new avenues for fabricating multifunctional composites of MOF and upconversion nanomaterials for varied applications.

Thermal Conversion of MOF@MOF: Synthesis of an N-Doped Carbon Material with Excellent ORR Performance

Here we propose a new strategy in which two isomorphic metal-organic frameworks (MOFs) [FJU-40-H (a) and FJU-40-NH₂ (b)] are used to construct the core-shell material MOF@MOF. This strategy based on nitrogen doping and specific surface has resulted in an N-doped porous carbon (NPC) material in a one-step thermal treatment in N₂ atmosphere; this material displays high catalytic activity for the oxygen reduction reaction (ORR). The materials were analyzed by SEM, XPS, Raman, specific surface area, pore size distribution and electrochemical measurements. It was found that NPC derived from the core-shell MOF@MOF can provide excellent catalytic ORR performance exceeding that of the single MOF. The onset potential is NPC-b@a-4h (-0.068 V)>NPC-a@b-4h (-0.075 V)>NPC-a-4h (-0.109 V)>NPC-b-4h (-0.113 V). Moreover, the results also show that the performance of NPC-b@a (n=4.15) is better than that of NPC-a@b (n=3.32), which means the different nitrogen content of ligands inside and outside of the core affects the ORR properties.

Novel nanoarchitecture of Co-MOF-on-TPN-COF hybrid: Ultralowly sensitive bioplatform of electrochemical aptasensor toward ampicillin

Owning to the misuse of the antibiotics in animal husbandry and agriculture, it is highly urgent to determine the quantification of antibiotics in biological systems by the simple, sensitive, and fast method. In this work, a novel nanoarchitecture of Co-based metal-organic frameworks (Co-MOF) and terephthalonitrile-based covalent organic framework (TPN-COF) was synthesized (represented by Co-MOF@TPN-COF), followed by the exploitation as the bioplatform of non-label aptasensor for detecting the most frequently used β-lactam antibiotics, ampicillin (AMP). The new porous hybrid material of Co-MOF@TPN-COF was synthesized by adding the as-prepared TPN-COF into the Co-MOF preparation system. The multilayered Co-MOF@TPN-COF nanosheets exhibit a high specific surface area (52.64 m² g^-1), nitrogen-rich groups and excellent electrochemical activity. As a result, large amounts of aptamer strands can be bound over the Co-MOF@TPN-COF nanosheets owning to the strong π-π stacking and hydrogen bonds. When detecting AMP by the electrochemical impedance spectroscopy, the fabricated Co-MOF@TPN-COF-based aptasensor exhibits an ultra-low detection limit of 0.217 fg mL^-1 within the AMP concentration from 1.0 fg mL^-1 to 2.0 ng mL^-1, which was superior to those previously reported in literatures. In addition, this proposed aptasensor also shows high selectivity, good reproducibility and stability, acceptable regenerability, and favorable applicability in human serum, river water and milk. Therefore, the proposed Co-MOF@TPN-COF-based aptasensor has a great promise to be applied as a powerful tool in the fields of food safety.

A mixed-ion strategy to construct CNT-decorated Co/N-doped hollow carbon for enhanced oxygen reduction

A series of carbon nanotube-decorated Co/N-doped hollow carbon (CNTs-Co/NHC) hybrids are precisely controlled by using a mixed-ion strategy.

Cobalt nanoparticles incorporated into hollow doped porous carbon capsules as a highly efficient oxygen reduction electrocatalyst

MOF nanocrystals are employed for the design and synthesis of cobalt nanoparticles embedded into hollow doped porous carbon electrocatalyst.

Copper-catalyzed one-pot domino reactions via C–H bond activation: synthesis of 3-aroylquinolines from 2-aminobenzylalcohols and propiophenones under metal–organic framework catalysis

A Cu₂(OBA)₂(BPY) metal–organic framework was utilized as a productive heterogeneous catalyst for the synthesis of 3-aroylquinolines via one-pot domino reactions of 2-aminobenzylalcohols with propiophenones. This Cu-MOF was considerably more active towards the one-pot domino reaction than a series of transition metal salts, as well as nano oxide and MOF-based catalysts. The MOF-based catalyst was reusable without a significant decline in catalytic efficiency. To the best of our knowledge, the transformation of 2-aminobenzylalcohols to 3-aroylquinolines was not previously reported in the literature, and this protocol would be complementary to previous strategies for the synthesis of these valuable heterocycles.

Cu₂(OBA)₂(BPY) metal–organic framework was utilized as a productive heterogeneous catalyst for the synthesis of 3-aroylquinolines via one-pot domino reactions of 2-aminobenzylalcohols with propiophenones.

Polycarboxylate-directed semi-rigid pyridyl-amide-based various NiII complexes: electrochemical properties and enhancements of photocatalytic activities by calcination

Four different pyridyl-amide-based Ni-complexes were synthesized by tuning polycarboxylates, displaying bifunctional electrocatalytic properties and enhancements of photocatalytic activities by calcination.

Photonic functional metal–organic frameworks

The recent progress in photonic MOFs for luminescence sensing, white-light emission, photocatalysis, nonlinear optics, lasing devices, and biomedicine is summarized.

Cooperative effects of metal cations and coordination modes on luminescent s-block metal–organic complexes constructed from V-shaped 4,4′-sulfonyldiphenol

Thirteen s-block metal–organic complexes with different supramolecular networks arising from the coordination modes of the ligands and properties of the metal cations have been synthesized and exhibit violet and blue luminescence in the solid state at room temperature.

The interlocked in situ fabrication of graphene@prussian blue nanocomposite as high-performance supercapacitor

High-quality graphene@prussian blue (G@PB) nanocomposite sheets fabricated via the one-step in situ hydrothermal method show great promise for energy-storage hybrid electrodes with excellent electrochemical performance.