Metal-organic Frameworks Research Articles

Organic-inorganic hybrids: A comprehensive review on synthesis and their potential applications

Organic-inorganic hybrids highlight the advantages of the presence of organic compounds, due to their stability, flexibility, and adaptability, as well as the structural features of inorganic materials. This review delves into the interaction between conducting polymers (CPs) and metal oxides (MOs), showcasing their combined advantages in various sectors such as sensors, capacitors, catalysts, and fuel cells. This paper explores the synthesis methods of prominent CPs including Polypyrrole (PPy), Polyaniline (PANI), Poly(3,4-ethylene dioxythiophene) (PEDOT), and Polyindole (PIn), along with a spectrum of MOs like zinc oxide (ZnO), copper oxide (CuO), titanium dioxide (TiO2), manganese dioxide (MnO2), iron oxides (Fe2O3 and Fe3O4), and nickel oxide (NiO). Diverse preparation techniques such as chemical oxidative, emulsion, and interfacial polymerization for CPs have been reported. Hydrothermal, co-precipitation, and sol-gel methods have been studied to synthesize MOs. Advanced characterization techniques such as Field emission scanning electron microscopy (FESEM), Energy dispersive X-ray analysis (EDAX), Transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) have been reported to study the structural and morphological aspects of CP-MO hybrids. These hybrids exhibit potential applications in sensors, biosensors, antimicrobial activity, energy storage devices, and photocatalysis. This review provides a comprehensive overview, which aims to explore the prospects and innovations in the area of organic-inorganic hybrids.

Influence of MIL-53 on the catalytic performance of metallocene in propylene polymerization

In this study, we investigate the application of metal-organic frameworks (MOFs) as a support for metallocene catalysts in the polymerization of propylene. MOFs such as MIL-53 and other conventional supports, SBA-15 and SiO2, were employed to immobilize the Me2Si(2-Me-4-PhInd)2ZrCl2 catalyst activated with methylaluminoxane (MAO). The effects of the physicochemical properties of these supports on catalytic performance and polymer properties were investigated. MIL-53, characterized by its channel structure, facilitated higher molecular weight polypropylene production and exhibited double the catalytic activity of SBA-15 and SiO2 supports. The MIL-53/MAO/Me2Si(2-Me-4-PhInd)2ZrCl2 catalyst also demonstrated higher comonomer incorporation and lower polymer melting points. The higher activity, elevated molecular weight, and increased reactivity towards 1-hexene of the MIL-53/MAO/Me2Si(2-Me-4-PhInd)2ZrCl2 catalyst are attributed to the electronic and steric effects of MIL-53. This study underscores the significant role of MOF structure in influencing polymerization behavior and highlights the potential of MOF-supported catalysts for tailored polymer properties.

Self-adaptive Coordination Evolution Mediated Pore-Space-Partition in Metal-Organic Frameworks for Boosting SF6/N2 Separation.

The controllable and precise structural regulation of metal-organic frameworks (MOFs) based on isoreticular chemistry is an effective strategy for creating functional material platforms, such as efficient porous adsorbents. Herein, for the first time, mediated by an unprecedented self-adaptive coordination evolution (SACE) on pseudo-D2h-symmetric [M4(μ3-O)2(COO)6] (M = Mn/Fe) clusters, two pore space partitioned MOFs (CTGU-47-Mn/Fe, CTGU = China Three Gorges University) have been successfully constructed. Owing to the more confined adsorption space and dense binding sites produced by pore space partitioning (PSP), the CTGU-47-Mn/Fe exhibit significantly enhanced performance in the capture or recovery SF6 (greenhouse/electronic specialty gas) from SF6/N2 mixture compared to their non-partitioned homologous structures (CTGU-46-Mn/Fe) with adsorption selectivity increased from 37/72 to 634/157 (v/v, 10/90, 100 kPa). The theoretical calculations also elucidated that the implementation of PSP within CTGU-47-Mn/Fe leads to dramatically strengthened binding affinity for SF6 over N2 through extra multiple F···H interactions. This study represents a valuable advance in crystal engineering field: the SACE of polynuclear metal clusters is expected to be useful in the structural regulation of MOFs and the fabrication of advanced porous adsorbents.

Gold/platinum nanorods/temozolomide-UiO-66-NH2 metal-organic frameworks incorporated to chitosan-grafted polycaprolactone/polycaprolactone core-shell nanofibers for glioblastoma treatment during chemo-photothermal therapy

The use of biocompatible metal-organic frameworks (MOFs) and electrospun nanofibrous implants shows promise in preventing the recurrence of postsurgical glioblastoma. In this study, temozolomide (TMZ) and platinum‑gold nanorods (PtAu NRs) were encapsulated into the UiO-66-NH2 MOFs. These were then incorporated into the chitosan-grafted polycaprolactone (PCL) (core)/PCL (shell) nanofibers coated with PtAu NRs for extended release of TMZ during chemo-photothermal therapy against glioblastoma cells. The drug encapsulation efficiency, TMZ release, and in vitro cell viability were investigated for the MOFs, simple nanofibers, core-shell nanofibers, and MOFs-nanofibers. The extended release of TMZ occurred over 44 and 36 days from the core-shell nanofibers coated with PtAu NRs under NIR irradiation at pH values of 7.4 and 5, respectively. The maximum killing of U87 glioblastoma cells was 80.2 % using TMZ-Pt-Au-MOF-core-shell nanofibers coated with PtAu under NIR irradiation. The relative tumor size for the mice bearing glioblastoma and treated with pure core-shell nanofibers, TMZ-Pt-Au-MOF, and TMZ-Pt-Au-MOF-core-shell nanofibers coated with PtAu without NIR irradiation and with NIR irradiation was 4.12, 2.12, 1.65, 0.86, and 0.48, respectively, after 30 days. The synthesized MOF-core-shell nanofibers-Pt-Au NRs implantable device shows potential as a new approach for postsurgical glioblastoma treatment during chemo-photothermal therapy.

Development and Characterization of PVA Membranes Modified with In(BTC) Metal–Organic Framework for Sustainable Pervaporation Separation of Isopropanol/Water

Development and Characterization of PVA Membranes Modified with In(BTC) Metal–Organic Framework for Sustainable Pervaporation Separation of Isopropanol/Water

Comprehensive analysis of a novel antimony-based organic-inorganic hybrid material: structural, vibrational, and hirshfeld surface investigations of (C8H14N2)[SbCl5]

The novel organic-inorganic hybrid compound, N,N’-di(4-ethyl aminomethyl)pyridinium pentachloride antimonate (III), designated as (C8H14N2)[SbCl5], was synthesized and crystallized through a slow evaporation technique to facilitate comprehensive analysis of its crystal structure and molecular composition. Single-crystal X-ray diffraction revealed that this supramolecular compound crystallizes in the centrosymmetric space group P21/n within the orthorhombic system. The unit cell parameters were determined as follows: a = 10.8365(3) Å, b = 11.8067(3) Å, c = 12.0281(3) Å, and β = 106.920(3)°. The crystal structure was solved using direct methods and refined via the least squares technique, yielding final values of R1 = 0.0218 and wR2 = 0.0444. To further confirm the structure's stability and coherence, we investigated various interaction types and the contribution of hydrogen bonding to the overall molecular interactions through Hirshfeld surface analysis. This analysis, complemented by 2D fingerprint plots, highlighted the predominance of Cl⋯H/H⋯Cl interactions, which accounted for 59.1 % of the total interactions. Additionally, the study of crystal voids indicated that 7.1 % of the unit cell volume is composed of void space, contributing to the mechanical strength of the compound. Furthermore, FTIR spectroscopy and Raman scattering were utilized to identify the functional and molecular groups within the crystal by analyzing their vibrational modes.

A Dual-Functional and Efficient MOF-5@MWCNTs Electrochemical Sensing Device for the Measurement of Trace-Level Acetaminophenol and Dopamine

The design and construction of dual-functional and high-efficiency electrochemical sensors are necessary for quantitative detection. In this work, a zinc-based metal–organic framework (MOF-5) and multi-walled carbon nanotubes (MWCNTs) were combined in situ through a simple solvothermal reaction to obtain an MOF-5@MWCNTs composite. The composite exhibits a large surface area, hierarchical pore structure, excellent conductivity, and enhanced electrochemical performance in the detection of acetaminophenol (AP) and dopamine (DA). Remarkably, the synergistic effects between MOF-5 and MWCNTs enable the electrochemical sensor based on the MOF-5@MWCNTs composite to quantitatively determine AP and DA at trace levels. Under optimal conditions, the proposed sensor features relatively wide linear ranges of 0.005–600 μM and 0.1–60 μM for AP and DA, respectively, with very low detection limits (LODs) of 0.061 μM and 0.0075 μM for AP and DA. Importantly, this electrochemical sensor demonstrates excellent reproducibility, stability, and anti-interference ability, making it suitable for practical applications in the detection of AP and DA in urine and tap water samples with acceptable recoveries. The successful integration of MOF-5 with MWCNTs results in a robust and versatile electrochemical sensing platform for the rapid and reliable detection of AP and DA at trace levels.

Engineered cell membrane-cloaked metal-organic framework nanocrystals for intracellular cargo delivery

This investigation demonstrates the development and functionality of cell membrane-cloaked UiO-67 nanosized metal–organic frameworks (NMOFs), which are engineered for precise intracellular delivery of encapsulated cargoes. Utilizing the robust and porous nature of UiO-67, we enveloped these NMOFs with fusogenic cell membrane-derived nanovesicles (FCSMs) sourced from adenocarcinomic human alveolar basal epithelial (A549) cells. This biomimetic coating enhances biocompatibility and leverages the homotypic targeting capabilities of the cell-derived coatings, facilitating direct cytoplasmic delivery and avoiding endolysosomal entrapment. Our nanoplatform exhibited high efficiency in loading and releasing two model cargoes: cresyl violet (CV), a staining agent, and carboplatin (CbPt), a chemotherapeutic agent. This approach demonstrated substantial potential in drug delivery in both 2D cell cultures and 3D spheroids. This study underscores the enhanced cellular uptake facilitated by the engineered biomimetic shell and highlights the system’s capacity for sustained release, offering a promising strategy for targeted drug delivery.

A Manganese-Doped Cerium-Based Metal–Organic Framework as a Radical Scavenger for Proton Exchange Membrane Fuel Cells with Superior Stability

A Manganese-Doped Cerium-Based Metal–Organic Framework as a Radical Scavenger for Proton Exchange Membrane Fuel Cells with Superior Stability

MIL-101 (Fe)-NH2/multi-walled carbon nanotubes nanocomposite modified glassy carbon electrode for simultaneous voltammetric determination of methotrexate and calcium folinate

Methotrexate (MTX), a structural analog of folic acid, known as one of the most potent and widely used medications for the treatment of different types of cancer and autoimmune diseases. However, the long-term treatment with MTX can cause various side effects. Calcium folinate (CF) is usually used with MTX to reduce the toxicity of MTX and enhance the efficacy of treatment. Therefore, the simultaneous determination of MTX and CF is very important. In this study a nanocomposite consisting of Fe-based metal–organic framework (MIL-101 (Fe)-NH2) and multi-walled carbon nanotubes MWCNTs) was synthesized by solvothermal method. The morphology and structure of the MIL-101 (Fe)-NH2/MWCNTs nanocomposite were investigated by various techniques. Then, a glassy carbon electrode modified with synthesized nanocomposite (MIL-101(Fe)-NH2/MWCNTs/GCE) was employed as a working electrode for voltammetric detection of MTX. Compared with un-modified GCE, the MIL-101 (Fe)-NH2/MWCNTs/GCE showed good electro-catalytic performance for oxidation of MTX. Under optimal conditions, the oxidation peak currents of MTX exhibit a linear relationship with its concentration in the range of 0.1–300.0 μM, and the limit of detection (LOD) is 0.04 μM. Also, the MIL-101 (Fe)-NH2/MWCNTs/GCE showed good activity towards MTX determination in the presence of CF. The separation of the oxidation peak potentials (200 mV), indicating its suitability for the simultaneous detection of these two drugs using differential pulse voltammetry (DPV). Finally, applicability of the developed sensor was verified by MTX and CF analysis in the pharmaceutical specimens with excellent results (recovery 96.9–103.4 %, and relative standard deviation (RSD) ≤ 3.6 %).

Exploring electronic structure and photophysical properties of metalloporphyrin-based metal–organic frameworks for photocatalysis: A quantum chemistry study

Hydrogen production is gaining interest as a clean energy source, with photocatalytic water-splitting being a key method due to its eco-friendly nature. Metalloporphyrins-based MOFs (TCPP(M)-MOFs), due to their tunable optical properties, are excellent materials for hydrogen evolution via water-splitting using sunlight. In this research, TCPP(M)-MOFs containing nodes based on metal ion d10 Zn2+ and TCPP(M) as linkers (M = Fe2+, Ni2+, Co2+and Cu2+) has been studied using theoretical approach. The electronic structure and optical properties of all Zn-TCPP(M)-MOFs were investigated using the density functional theory (DFT) and periodic-DFT calculations. The study revealed a bandgap reduction related to the open-shell metals in the TCPP linker, with an optimal value for the photocatalytic process under sunlight. TD-DFT calculations show that the inclusion of open shell ions enhances the linker-centered ligand-to-metal charge transfer process. Finally, it was suggested some directions for the design of new melloporphyrine-based MOFs, potentially leading to new materials for photocatalytic water-splitting.

One-stone-for-two-birds strategy to construct robust 2D conjugated metal-organic framework-based quasi-solid-state lithium-organic batteries

Quasi-solid-state lithium batteries (QSSLBs) are emerging as attractive candidates for overcoming the disadvantages of liquid and solid batteries. However, they face challenges in terms of enhancing the poor interfacial stability and promoting selective Li+ conduction. Herein, one-stone-for-two-birds strategy is proposed that involves using a two-directional conjugated metal organic framework (2D-cMOF, Fe-TABQ) as both the cathode material and a polymer–electrolyte filler to construct high-performance quasi-solid-state lithium–organic batteries (QSSLOBs). Additionally, Fe-TABQ promotes the cleavage of C–F bonds, thus facilitating the formation of a LiF-rich solid electrolyte interface (SEI). Therefore, the composite polymer electrolyte presents a high Li+ transference number of 0.93 and a high ionic conductivity of 6.22 × 10−3 mS cm−1. Meanwhile, Li/Li symmetric cells deliver stable cyclability for 1,500 h at 25 ℃ and a current density of 0.05 mA cm−2. Even the assembled QSSLOBs exhibit a high initial discharge specific capacity of 248.39 mAh/g at 25 ℃, and 50 mA g−1 and long cycle stability with 70 % capacity retention after 200 cycles at 25 ℃ and 1,000 mA g−1. The present findings reveal the multiple functional potentials of 2D-cMOFs in constructing robust QSSLOBs.

Magnetic metal-organic frameworks-based ratiometric SERS aptasensor for sensitive detection of patulin in apples

Patulin (PAT), a major contaminant in apples, poses a considerable food safety risk, necessitating a rapid, sensitive and reliable detection method. This study developed a novel magnetic metal-organic frameworks (MOFs)-based ratiometric surface-enhanced Raman scattering (SERS) aptasensor. The sensor consists of magnetic MOFs loaded with 4-Mercaptobenzoic acid (4-MBA) internal labeled AuMBA@Ag as the SERS substrate, and gold nanorods (AuNRs) modified with Rhodamine 6G and aptamers as capture probes. This strategy enhances sensitivity through magnetic separation and abundant SERS hotspots provided by the magnetic MOF nanocomposites. The SERS intensity ratio showed a negative correlation with PAT concentrations from 0.01 to 100 ng/mL, with a LOD of 0.0465 ng/mL. Moreover, the aptasensor achieved 95.90 % ∼ 105.83 % recoveries in apple samples, indicating high accuracy and anti-interference capability. The excellent sensing performance demonstrates great potential of the SERS nanosensor for mycotoxin detection in actual food matrices.

Regulating electrons transfer through Pd-O-Bi bridges for boosting photocatalytic CO2 reduction

The photocatalytic efficiency of bismuth-based metal-organic framework (Bi-MOF) is extremely restricted by the rapid recombination of photogenerated electron-hole pairs, which reduce the number of electrons involved in the photocatalytic reduction reaction. Constructing precise interfacial bond bridges between metal nanoparticles (NPs) and MOFs has emerged as an effective strategy to address the above-mentioned issues, promoting the electrons transfer. Herein, this study improves the sluggish dynamics of photogenerated charge in Bi-MOF by inducing the Pd-O-Bi bond bridges at the interface on a Pd NPs-decorated Bi-MOF (Pd/Bi-MOF) nanosheets. This phenomenon results in an interaction between Pd NPs and the Bi-MOF support. And Pd-O-Bi bond bridges provide the fast electron transfer channels, triggering the directional migration of photogenerated electrons from Pd to Bi node, then enhancing the spatial separation of photogenerated electron-hole pairs, finally facilitating overall photocatalytic CO2 reduction. The presence of these bond bridges leads to higher enhancement in CO production for Pd/Bi-MOF nanosheets compared to the Bi-MOF nanosheets under visible light irradiation after 4.5 h. This research demonstrates the importance of interfacial bond bridges and provides a reasonable guide to design efficient photocatalyst for reduction of CO2 to CO.

Unraveling MOF growth in colloids with controllable dual-doping through ultrafast sintering for wide temperature range LIBs

Metal-organic frameworks (MOFs) offer versatile building blocks for high-performance materials across practical applications. Crystallization studies reveal MOF complex pathways crucial for biological and synthetic systems, yet understanding remains incomplete. Here, we employ in-situ liquid phase transmission electron microscopy (LPTEM) to scrutinize the growth dynamics of ZIF-8 in colloidal environments, aiming to deepen our comprehension of MOF crystallization. This study employs in-situ LPTEM to investigate ZIF-8 nanoparticle growth, revealing the combination of classical and non-classical nucleation processes in the same batch leading a challenge to control nanoparticle morphology and size, while heterogeneous nucleation is dominant giving monodispersed nanoparticle at the presence of ZIF-8 seeds in mother solution. Additionally, integrating MOF-derived carbon materials in lithium-ion batteries (LIBs) faces challenges in achieving high-performance, controllable N-doping and long-term stability. Ultrafast high-temperature sintering (UHS) is utilized to carbonize ZIF-8, regulating N-doping hard carbon with Zn single atoms doping. Results show optimal morphology at 800 °C for 20 s, yielding higher concentration of Zn-doping, higher N-doping levels, and good conductivity compared to conventional sintering in tube furnace. LIB tests demonstrate exceptional cycling performance and stability across wide temperatures. This UHS strategy for ZIF-8 contributes to establishing a balance between Zn-N-doping and the degree of graphitization, thus providing an interdisciplinary approach that offers efficient MOF derivative synthesis for promising wide temperature range applications of LIBs.

In Situ Phase Transformation-Enabled Metal-Organic Frameworks for Efficient CO2 Electroreduction to Multicarbon Products in Strong Acidic Media.

The electrochemical CO2 reduction reaction (CO2RR) has been acknowledged as a promising strategy to relieve carbon emissions by converting CO2 to essential chemicals. Despite significant progresses that have been made in neutral and alkaline media, the implementation of CO2RR in acidic conditions remains challenging due to the harsh conditions, especially in producing high-value multicarbon products. Here, we report that Cu-btca (btca = benzotriazole-5-carboxylic acid) metal-organic framework (MOF) nanostructures can act as a stable catalyst for the CO2RR in an acidic environment. The Cu-btca MOF undergoes phase transformation and morphology evolution during electrolysis, forming a stable porous Cu-btca MOF network. The resultant MOF network exhibits excellent selectivity toward ethylene and multicarbon products with Faradaic efficiencies of 51.2% and 81.9%, respectively, in a strong acidic electrolyte with a flow cell at 300 mA/cm2. Mechanism studies uncover that the Cu-btca MOF network can limit the proton reduction to suppress hydrogen evolution and maintain high local *CO concentration to promote CO2RR. Theoretical calculations suggest that two adjacent Cu sites in the Cu-btca MOF provide a favorable microenvironment for carbon-carbon coupling, facilitating the multicarbon production. This work reveals that rational structure control of MOFs can enable highly selective and efficient CO2 electroreduction to multicarbon products in strong acidic conditions toward practical applications.

Engineered Conductive Metal-organic Frameworks for Electrochemical Detection of Urinary Biomarkers.

The increasing prevalence of health concerns has sparked a demand for advanced health monitoring tools, which is a significant challenge for researchers. Analysis of biofluid samples and biomarker monitoring is vital for comprehensive health assessment. In this context, metal-organic frameworks (MOFs) have emerged as one of the leading materials for developing cutting-edge artificial sensors. These unique MOFs have been developed from metallic and organic linkers and consist of tunable pores and dynamic surface areas, attracting various guest molecules to participate in developing advanced electrochemical devices. This study is a gateway to a world where MOF designs transcend mere inventions, morphing into electric marvels that revolutionize urine sample monitoring. From the inception and design to the fabrication of MOF sensors tailored for electrochemical applications, this study prides itself on elucidating the factors affecting MOF-based electrical devices and sensors. Moreover, the focus is placed on conductivity, electrode properties, and recent state-of-the-art urine sample analysis, highlighting the pivotal role biomarkers play in honing the resilience and performance of the sensors. Finally, this study is specific to electrochemical sensors used for urine analysis. It will attract researchers to develop new portable tools for health monitoring by analyzing urine samples.

Adsorptive-dissolution of O2 into the potential nanospace of a densely fluorinated metal-organic framework

Nanoporous solids, including metal-organic frameworks (MOFs), have long been known to capture small molecules by adsorption on their pore surfaces. Liquids are also known to accommodate small molecules by dissolution. These two processes have been recognized as fundamentally distinct phenomena because of the different nature of the medium—solids and liquids. Here, we report a dissolution-like gas accommodation so-called “adsorptive-dissolution” behavior in a MOF (PFAC-2) with pores densely filled with perfluoroalkyl chains. PFAC-2 does not have solvent-accessible voids; nevertheless, it captures oxygen molecules without changing the framework structure, analogous to molecular dissolution into liquids. Moreover, we demonstrate the selective capture of O2 by PFAC-2 in a mixture of O2 and Ar, which are difficult to separate due to their similarities such as boiling point and molecular size. Our results show the integration of molecular adsorption into nanospaces and dissolution into fluorous solvents, which can guide the design of crystalline adsorbents for selective molecular trapping and gas separation.

Molecular imprinting resonant light scattering sensor based on teamed boronate affinity for highly specific detection of glycoprotein

It is challenging to detect and enrich glycoproteins in complex biological samples because they are low in natural abundance, highly flexible in conformation and there are many interfering substances in the samples. To overcome these challenges, magnetic Fe3O4 nanoparticles (NPs) were prepared, in which the surface was modified by metal–organic frameworks (MOFs) and then by molecularly imprinted polymers (MIPs). Combined with the teamed boronate affinity (TBA) strategy, the selectivity and sensitivity detection of glycoprotein ovalbumin (OVA) were realized. The magnetic Fe3O4 NPs were coated with MOFs to facilitate the adsorption of AuNPs, onto which the TBA moieties composed of 2-mercaptoethylamine and 4-mercaptophenylboronic acid were pre-assembled. The final magnetic Fe3O4@TBA/MIPs NPs featured shallow imprinted cavities, resulting in rapid mass transfer of the target glycoprotein (equilibrium time 20 min). In particular, the TBA strategy relied on N-B synergy, resulting in high specificity (IF = 4.52) and high sensitivity (limit of detection 13 pM) for the detection of OVA at physiological pH (7.4). This strategy provides an extremely convenient method for detecting and quantifying low-abundance glycoprotein in complex biological samples, without destroying the structure and function of the target glycoprotein.

Co3O4/MnO2 shell layer nanocage derived MOF deposited on nickel foam for effective electrochemical detection of hydrogen peroxide

Cobalt-based Metal Organic Framework (MOF) materials are considered by recent researchers as one of the most promising materials in the field of electrochemical sensing due to their unique properties. In this paper, ZIF-67-derived Co3O4/MnO2 shell-structured nanomaterials were synthesized by a hydrothermal method and deposited onto nickel foam for performing a series of performance sensing experiments as an enzyme-free H2O2 electrochemical sensor. The resulting Co3O4/MnO2/Ni foam material exhibited excellent sensing performance for H2O2, with a low detection limit of 1.67 μM (S/N = 3); a high sensitivity of 1557 μA mM−1 cm−2; a wide linear range of 2.0 μM to 2.5 mM (R2 = 0.992) and a good selectivity and long-term stability. The Co3O4/MnO2 shell nanomaterials provided a large mesopore and specific surface area, which enhanced the catalytic activity of Co3O4/MnO2 for H2O2. These results indicate that Co3O4/MnO2/Ni foam is a promising material for electrochemical sensing.