A tumor microenvironment-activated metal-organic framework-based nanoplatform for amplified oxidative stress-induced enhanced chemotherapy.

Engineering a highly tumor microenvironment-responsive nanoplatform toward effective chemotherapy has always been a challenge in targeted cancer treatment. Metal-organic frameworks are a promising delivery system to reformulate previously approved drugs for enhanced chemotherapy, such as disulfiram (DSF). Herein, a tumor microenvironment-activated metal-organic framework-based nanoplatform DSF@MOF-199@FA has been fabricated to realize amplified oxidative stress-induced enhanced chemotherapy. Our results unveil that the copper ions and DSF released by DSF@MOF-199@FA in an acidic environment can be converted into toxic bis(N, N-diethyl dithiocarbamate) copper and then induce cell apoptosis. Simultaneously, we determined that the apoptosis outcome is further promoted by amplified oxidative stress through effective generation of reactive oxygen species and GSH elimination. In conclusion, this work provides a promising platform for effective anticancer treatment.

Mapping the correlations between bandgap, HOMO, and LUMO trends for meta substituted Zn-MOFs.

Bandgap is a key property that determines electrical and optical properties in materials. Modulating the bandgap thus is critical in developing novel materials particularly semiconductors with improved features. This study examines the bandgap, highest occupied molecular orbital (HOMO), and lowest unoccupied molecular orbital (LUMO) energy level trends in a metal organic framework, metal-organic framework 5 (MOF-5), as a function of Hammett substituent effect (with the constant σm in the meta-position of the benzene ring) and solvent dielectric effect (with the constant ε). Specifically, experimental design and response surface methodologies helped to assess the significance of trends and correlations between these molecular properties with σm and ε. While the HOMO and LUMO decrease with increasing σm, the LUMO exhibits greater sensitivity to the substituent's electron withdrawing capability. The relative difference in these trends helps to explain why the bandgap tends to decrease with increasing σm.

Hierarchical Porous Amidoximated Metal-Organic Framework for Highly Efficient Uranium Extraction.

With the rapid development of industry and technology, high-efficiency extraction of uranium from seawater is a research hotspot from the aspect of nuclear energy development. Herein, a new amidoximated metal-organic framework (UiO-66-DAMN-AO) constructed through a novel organic ligand of 2-diaminomaleonitrile-terephthalic acid (BDC-DAMN) is designed via one-step post-synthetic methods (PSM), which possess the merit of abundant multiaffinity sites, large specific surface area, and unique porous structure for efficient uranium extraction. Adopting one-step PSM can alleviate the destruction of structural stability and the reduction of the conversion rate of amidoxime groups. Meanwhile, introducing the BDC-DAMN ligand with abundant multiaffinity sites endow UiO-66-DAMN-AO with excellent adsorption ability (Qm = 426.3 mg g-1) and selectivity. Interestingly, the UiO-66-DAMN-AO has both micropores and mesopores, which may be attributed to the partial etching of UiO-66-DAMN-AO during the amidoximation. The presence of mesopores improves the mass transfer rate of UiO-66-DAMN-AO and provides more exposed active sites, favoring the adsorption of uranium on UiO-66-DAMN-AO. Thus, this study provides a feasible strategy for modifying metal-organic framework (MOFs) with plentiful amidoxime groups and the promising prospect for MOF-based materials to adsorb uranium from ocean.

A Highly Robust and Conducting Ultramicroporous 3D Fe(II)-Based Metal-Organic Framework for Efficient Energy Storage.

Exploitation of metal-organic framework (MOF) materials as active electrodes for energy storage or conversion is reasonably challenging owing to their poor robustness against various acidic/basic conditions and conventionally low electric conductivity. Keeping this in perspective, herein, a 3D ultramicroporous triazolate Fe-MOF (abbreviated as Fe-MET) is judiciously employed using cheap and commercially available starting materials. Fe-MET possesses ultra-stability against various chemical environments (pH-1 to pH-14 with varied organic solvents) and is highly electrically conductive (σ = 0.19 S m-1) in one fell swoop. By taking advantage of the properties mentioned above, Fe-MET electrodes give prominence to electrochemical capacitor (EC) performance by delivering an astounding gravimetric (304 F g-1) and areal (181 mF cm-2) capacitance at 0.5 A g-1 current density with exceptionally high cycling stability. Implementation of Fe-MET as an exclusive (by not using any conductive additives) EC electrode in solid-state energy storage devices outperforms most of the reported MOF-based EC materials and even surpasses certain porous carbon and graphene materials, showcasing superior capabilities and great promise compared to various other alternatives as energy storage materials.

Boosting Electrochemical CO2 Reduction on Copper-Based Metal-Organic Frameworks via Valence and Coordination Environment Modulation.

Cu-based metal-organic frameworks (MOFs) have attracted much attention for electrocatalytic CO2 reduction to high value-added chemicals, but they still suffer from low selectivity and instability. Here, an associative design strategy for the valence and coordination environment of the metal node in Cu-based MOFs is employed to regulate the CO2 electroreduction to ethylene. A novel "reduction-cleavage-recrystallization" method is developed to modulate the Cu(II)-Trimesic acid (BTC) framework to form a Cu(I)-BTC structure enriched with free carboxyl groups in the secondary coordination environment (SCE). In contrast to Cu(II)-BTC, the Cu(I)-BTC shows higher catalytic activity and better ethylene selectivity (≈2.2-fold) for CO2 electroreduction, which is further enhanced by increasing the content of free carboxyl groups, resulting in ethylene Faraday efficiency of up to 57% and the durability of the catalyst could last for 38 h without performance decline. It indicates that the synergistic effect between Cu(I)-O coordinated structure and free carboxyl groups considerably enhances the dimerization of *CO intermediates and hinders the hydrogenation of *CO intermediates in these competitive pathways. This work unravels the strong dependence of CO2 electroreduction on the Cu valence state and coordination environment in MOFs and provides a platform for designing highly selective electrocatalytic CO2 reduction catalysts.

Joint Exfoliation of MXene by Dimensional Mismatched SiC/ZIF-67 Toward Multifunctional Flame Retardant Thermoplastic Polyurethane.

The single-layer MXene fully demonstrates the advantages of 2D materials, especially catalytic, conductive, and mechanical properties. However, the high energy consumption and low efficiency faced by MXene in the divestiture process are still challenges that need to be solved urgently. In this article, dimension mismatch and collaborative stripping strategies are skillfully combined to easily realize the transformation from multi-layer MXene to single layer. In addition, the functionalized MXene@SiC@polyaniline (MXene@SiC@PANI) nano-hybrid materials are used as fillers to improve the thermal conductivity, flame retardant, and antibacterial properties of thermoplastic polyurethane (TPU). The surface temperature of TPU/MXene@SiC@PANI composites increased from 33.4 °C to 59.8 °C within 10 s. In addition, the antibacterial efficiency of TPU composites against Escherichia coli and Staphylococcus aureus is 69.6% and 88.9%, respectively. Compared with pure TPU, the peak heat release rate and total heat release are reduced by 71.4% and 34.6%, respectively. The flame-retardant mechanism of MXene hybrid materials is systematically discussed. It is worth noting that the introduction of PANI enhances the compatibility between the filler and the polymer, effectively maintaining the mechanical properties of the TPU itself. This work provides a convenient method for the multi-functional practical application of TPU.

Carboxyl-Decorated UiO-66 Supporting Pd Nanoparticles for Efficient Room-Temperature Hydrodeoxygenation of Lignin Derivatives.

Hydrodeoxygenation (HDO) of lignin derivatives at room-temperature (RT) is still of challenge due to the lack of satisfactory activity reported in previous literature. Here, it is successfully designed a Pd/UiO-66-(COOH)2 catalyst by using UiO-66-(COOH)2 as the support with uncoordinated carboxyl groups. This catalyst, featuring a moderate Pd loading, exhibited exceptional activity in RT HDO of vanillin (VAN, a typical model lignin derivative) to 2-methoxyl-4-methylpheonol (MMP), and >99% VAN conversion with >99% MMP yield is achieved, which is the first metal-organic framework (MOF)-based catalyst realizing the goal of RT HDO of lignin derivatives, surpassing previous reports in the literature. Detailed investigations reveal a linear relationship between the amount of uncoordinated carboxyl group and MMP yield. These uncoordinated carboxyl groups accelerate the conversion of intermediate such as vanillyl alcohol (VAL), ultimately leading to a higher yield of MMP over Pd/UiO-66-(COOH)2 catalyst. Furthermore, Pd/UiO-66-(COOH)2 catalyst also exhibits exceptional reusability and excellent substrate generality, highlighting its promising potential for further biomass utilization.

Metal-Organic Framework-Based Nanomaterials for Regulation of the Osteogenic Microenvironment.

As the global population ages, bone diseases have become increasingly prevalent in clinical settings. These conditions often involve detrimental factors such as infection, inflammation, and oxidative stress that disrupt bone homeostasis. Addressing these disorders requires exogenous strategies to regulate the osteogenic microenvironment (OME). The exogenous regulation of OME can be divided into four processes: induction, modulation, protection, and support, each serving a specific purpose. To this end, metal-organic frameworks (MOFs) are an emerging focus in nanomedicine, which show tremendous potential due to their superior delivery capability. MOFs play numerous roles in OME regulation such as metal ion donors, drug carriers, nanozymes, and photosensitizers, which have been extensively explored in recent studies. This review presents a comprehensive introduction to the exogenous regulation of OME by MOF-based nanomaterials. By discussing various functional MOF composites, this work aims to inspire and guide the creation of sophisticated and efficient nanomaterials for bone disease management.

Metal-Organic Framework (MOF)-Based Clean Energy Conversion: Recent Advances in Unlocking its Underlying Mechanisms.

Carbon neutrality is an important goal for humanity . As an eco-friendly technology, electrocatalytic clean energy conversion technology has emerged in the 21st century. Currently, metal-organic framework (MOF)-based electrocatalysis, including oxygen reduction reaction (ORR), oxygen evolution reaction (OER), hydrogen evolution reaction (HER), hydrogen oxidation reaction (HOR), carbon dioxide reduction reaction (CO2RR), nitrogen reduction reaction (NRR), are the mainstream energy catalytic reactions, which are driven by electrocatalysis. In this paper, the current advanced characterizations for the analyses of MOF-based electrocatalytic energy reactions have been described in details, such as density function theory (DFT), machine learning, operando/in situ characterization, which provide in-depth analyses of the reaction mechanisms related to the above reactions reported in the past years. The practical applications that have been developed for some of the responses that are of application values, such as fuel cells, metal-air batteries, and water splitting have also been demonstrated. This paper aims to maximize the potential of MOF-based electrocatalysts in the field of energy catalysis, and to shed light on the development of current intense energy situations.

Hollow Superstructure In Situ Assembled by Single-Layer Janus Nanospheres toward Electromagnetic Shielding Flame-Retardant Polyurea Composites.

A dodecahedral superstructure consisting of a single layer of Janus spheres containing ZIF-67 nanodots is prepared by in situ polymerization, with ZIF-67 and bio-based phytic acid (PA) as templates and dopants. It is used to improve the flame retardant, electromagnetic (EMI) shielding, and thermal conductivity properties of polyurea (PUA). By adding 5 wt% polyaniline@cobalt phytate-2.0 (PANI@Co-PA-2.0), the peak of heat release rate and the peak of smoke production rate are reduced by 54.9 and 59.9%, respectively. The peak of CO and CO2 production also decreased by 46.2 and 53.1%, respectively. A decrease in the absorption intensity of aliphatic and aromatic volatiles is also observed. The fire safety of PUA is greatly improved. In addition, PUA/PANI@Co-PA-2.0 exhibits an EMI shielding capability of 22.4 dB with the help of reduced graphene oxide, which confirms the possibility of PUA material application in the field of electromagnetic shielding. The 5 wt% filler increases the tensile strength of the PUA matrix to 6.3 MPa, and the composite material obtains good thermal conductivity. This work provides a viable method for the preparation of a flame-retardant, conductive, and electromagnetic refractory PUA substrate.

Binder-Free MOF-Based and MOF-Derived Nanoarrays for Flexible Electrochemical Energy Storage: Progress and Perspectives.

The fast development of Internet of Things and the rapid advent of next-generation versatile wearable electronics require cost-effective and highly-efficient electroactive materials for flexible electrochemical energy storage devices. Among various electroactive materials, binder-free nanostructured arrays have attracted widespread attention. Featured with growing on a conductive and flexible substrate without using inactive and insulating binders, binder-free 3D nanoarray electrodes facilitate fast electron/ion transportation and rapid reaction kinetics with more exposed active sites, maintain structure integrity of electrodes even under bending or twisted conditions, readily release generated joule heat during charge/discharge cycles and achieve enhanced gravimetric capacity of the whole device. Binder-free metal-organic framework (MOF) nanoarrays and/or MOF-derived nanoarrays with high surface area and unique porous structure have emerged with great potential in energy storage field and been extensively exploited in recent years. In this review, common substrates used for binder-free nanoarrays are compared and discussed. Various MOF-based and MOF-derived nanoarrays, including metal oxides, sulfides, selenides, nitrides, phosphides and nitrogen-doped carbons, are surveyed and their electrochemical performance along with their applications in flexible energy storage are analyzed and overviewed. In addition, key technical issues and outlooks on future development of MOF-based and MOF-derived nanoarrays toward flexible energy storage are also offered.

Multiple Electron Transfer in Semiconductive Ternary D-D'-A Metal-Organic Framework for Enhanced X-Ray Detection and Imaging.

Semiconductive metal-organic frameworks (MOFs) with donor-acceptor (D-A) characteristics have garnered attractive attention due to their capacity for separating and transferring photogenerated charges, making them promising candidates for high-performance X-ray detectors. However, the low charge transfer efficiency between the metal nodes and organic ligands limits the X-ray-to-electricity conversion efficiency of these materials. Herein, an additional photoactive donor (D') is introduced by incorporating a heavy atom-containing polyoxometalate (POM) [α-SiW12O40]4- into a binary {[Ni·bcbp·(H2O)2]·(H2O)4·Cl}n (Ni-bcbp, bcbp: H2bcbp·2Cl = 1,1'-bis(4-carboxyphenyl)(4,4'-bipyridinium) dichloride) MOF, resulting in a semiconductive ternary D-D'-A framework {[Ni2(bcbp)2·(H2O)4·(DMA)]·(SiW12O40)}n (SiW@Ni-bcbp, DMA: dimethylacetamide). The obtained material features an unprecedented porous 8-connected bcu-net structure that accommodates nanoscale [α-SiW12O40]4- counterions, displaying uncommon optoelectronic responses. In contrast to binary Ni-bcbp, the SiW@Ni-bcbp framework exhibits distinctive photochromism and robust X-ray responsiveness, which can be attributed to the synergistic effects of the electron reservoir and multiple photoinduced electron transfer originating from the POMs. As a result, the X-ray detector based on SiW@Ni-bcbp demonstrates a sensitivity of 5741.6 µC Gyair -1 cm-2 with a low detection limit of 0.49 µGyair s-1. Moreover, the devices demonstrated the capability of producing clearness X-ray images, providing a feasible and stable solution for constructing high-performance direct X-ray detectors.

Modulating 3d Charge State via Halogen Ions in Neighboring Molecules of Metal-Organic Frameworks for Improving Water Oxidation.

Modulating the coordination environment of the metal active center is an effective method to boost the catalytic performances of metal-organic frameworks (MOFs) for oxygen evolution reaction (OER). However, little attention has been paid to the halogen effects on the ligands engineering. Herein, a series of MOFs X─FeNi-MOFs (X = Br, Cl, and F) is constructed with different coordination microenvironments to optimize OER activity. Theoretical calculations reveal that with the increase in electronegativity of halogen ions in terephthalic acid molecular (TPA), the Bader charge of Ni atoms gets larger and the Ni-3d band center and O-2p bands move closer to the Fermi level. This indicates that an increase in ligand negativity of halogen ions in TPA can promote the adsorption ability of catalytic sites to oxygen-containing intermediates and reduce the activation barrier for OER. Experimental also demonstrates that F─FeNi-MOFs exhibit the highest catalytic activity with an ultralow overpotential of 218 mV at 10 mA cm-2, outperforming most otate-of-the-art Fe/Co/Ni-based MOFs catalysts, and the enhanced mass activity by seven times compared with that for the sample before ligands engineering. This work opens a new avenue for the realization of the modulation of NiFe─O bonding by halogen ion in TPA and improves the OER performance of MOFs.

Anchoring Ultrafine ß-Mo2C Clusters Inside Porous Co-NC Using MOFs for Electric-Powered Coproduction of Valuable Chemicals.

Electroredox of organics provides a promising and green approach to producing value-added chemicals. However, it remains a grand challenge to achieve high selectivity of desired products simultaneously at two electrodes, especially for non-isoelectronic transfer reactions. Here a porous heterostructure of Mo2C@Co-NC is successfully fabricated, where subnanometre ß-Mo2C clusters (<1 nm, ≈10 wt%) are confined inside porous Co, N-doped carbon using metalorganic frameworks. It is found that Co species not only promote the formation of ß-Mo2C but also can prevent it from oxidation by constructing the heterojunctions. As noted, the heterostructure achieves >96% yield and 92% Faradaic efficiency (FE) for aldehydes in anodic alcohol oxidation, as well as >99.9% yield and 96% FE for amines in cathodal nitrocompounds reduction in 1.0 M KOH. Precise control of the reaction kinetics of two half-reactions by the electronic interaction between ß-Mo2C and Co is a crucial adjective. Density functional theory (DFT) gives in-depth mechanistic insight into the high aldehyde selectivity. The work guides authors to reveal the electrooxidation nature of Mo2C at a subnanometer level. It is anticipated that the strategy will provide new insights into the design of highly effective bifunctional electrocatalysts for the coproduction of more complex fine chemicals.

Synthesis and Characterization of MOF-Derived Structures: Recent Advances and Future Perspectives.

Due to their facile tunability, metal-organic frameworks (MOFs) are employed as precursors and templates to construct advanced functional materials with unique and desired chemical, physical, mechanical, and morphological properties. By tuning MOF precursor composition and manipulating conversion processes, various MOF-derived materials commonly known as MOF derivatives can be constructed. The possibility of controlled and predictable properties makes MOF derivatives a preferred choice for numerous advanced technological applications. The innovative synthetic designs besides the plethora of interdisciplinary characterization approaches applicable to MOF derivatives provide the opportunity to perform a myriad of experiments to explore the performance and offer key insight to develop the next generation of advanced materials. Though there are many published works of literature describing various synthesis and characterization techniques of MOF derivatives, it is still not clear how the synthesis mechanism works and what are the best techniques to characterize these materials to probe their properties accurately. In this review, the recent development in synthesis techniques and mechanisms for a variety of MOF derivates such as MOF-derived metal oxides, porous carbon, composites/hybrids, and sulfides is summarized. Furthermore, the details of characterization techniques and fundamental working principles are summarized to probe the structural, mechanical, physiochemical, electrochemical, and electronic properties of MOF and MOF derivatives. The future trends and some remaining challenges in the synthesis and characterization of MOF derivatives are also discussed.

Ultrafast and Durable Sodium-Ion Storage of Pseudocapacitive VN@C Hybrid Nanorods from Metal-Organic Framework.

Vanadium nitride (VN) is a promising electrode material for sodium-ion storage due to its multivalent states and high electrical conductivity. However, its electrochemical performance has not been fully explored and the storage mechanism remains to be clarified up to date. Here, the possibility of VN/carbon hybrid nanorods synthesized from a metal-organic framework for ultrafast and durable sodium-ion storage is demonstrated. The VN/carbon electrode delivers a high specific capacity (352 mA h g-1), fast-charging capability (within 47.5 s), and ultralong cycling stability (10 000 cycles) for sodium-ion storage. In situ XRD characterization and density functional theory (DFT) calculations reveal that surface-redox reactions at vanadium sites are the dominant sodium-ion storage mechanism. An energy-power balanced hybrid capacitor device is verified by assembling the VN/carbon anode and active carbon cathode, and it shows a maximum energy density of 103 Wh kg-1 at a power density of 113 W kg-1.

Optimizing Iodine Enrichment through Induced-Fit Transformations in a Flexible Ag(I)-Organic Framework: From Accelerated Adsorption Kinetics to Record-High Storage Density.

Efficient capture and storage of radioactive I2 is a prerequisite for developing nuclear power but remains a challenge. Here, two flexible Ag-MOFs (FJI-H39 and 40) with similar active sites but different pore sizes and flexibility are prepared; both of them can capture I2 with excellent removal efficiencies and high adsorption capacities. Due to the more flexible pores, FJI-H39 not only possesses the record-high I2 storage density among all the reported MOFs but also displays a very fast adsorption kinetic (124 times faster than FJI-H40), while their desorption kinetics are comparable. Mechanistic studies show that FJI-H39 can undergo induced-fit transformations continuously (first contraction then expansion), making the adsorbed iodine species enrich near the Ag(I) nodes quickly and orderly, from discrete I- anion to the dense packing of various iodine species, achieving the very fast adsorption kinetic and the record-high storage density simultaneously. However, no significant structural transformations caused by the adsorbed iodine are observed in FJI-H40. In addition, FJI-H39 has excellent stability/recyclability/obtainability, making it a practical adsorbent for radioactive I2. This work provides a useful method for synthesizing practical radioactive I2 adsorbents.

Observation of a Reversible Order-Order Transition in a Metal-Organic Framework - Ionic Liquid Nanocomposite Phase-Change Material.

Metal-organic framework (MOF) composite materials containing ionic liquids (ILs) have been proposed for a range of potential applications, including gas separation, ion conduction, and hybrid glass formation. Here, an order transition in an IL@MOF composite is discovered using CuBTC (copper benzene-1,3,5-tricarboxylate) and [EMIM][TFSI] (1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide). This transition - absent for the bare MOF or IL - provides an extended super-cooling range and latent heat at a capacity similar to that of soft paraffins, in the temperature range of ≈220 °C. Structural analysis and in situ monitoring indicate an electrostatic interaction between the IL molecules and the Cu paddle-wheels, leading to a decrease in pore symmetry at low temperature. These interactions are reversibly released above the transition temperature, which reflects in a volume expansion of the MOF-IL composite.

Control of ZIF-62 and agZIF-62 Film Thickness within Asymmetric Tubular Supports through Pressure and Dose Time Variation of Atomic Layer Deposition.

Thin-films of metal-organic frameworks (MOFs) have widespread potential applications, especially with the emergence of glass-forming MOFs, which remove the inherent issue of grain boundaries and allow coherent amorphous films to be produced. Herein, it is established that atomic layer deposition (ALD) of zinc oxide lends excellent control over the thickness and localization of resultant polycrystalline and glass zeolitic imidazole framework-62 (ZIF-62) thin-films within tubular α-alumina supports. Through the reduction of the chamber pressure and dose times during zinc oxide deposition, the resultant ZIF-62 films are reduced from 38 µm to 16 µm, while the presence of sporadic ZIF-62 (previously forming as far as 280 µm into the support) is prevented. Furthermore, the glass transformation shows a secondary reduction in film thickness from 16 to 2 µm.

Effective Reduction of CO2 with Aromatic Amines into N-Formamides Triggered by Noble-Free Metal-Organic Framework Catalysts Under Mild Conditions.

The reductive transformation of carbon dioxide (CO2) into high-valued N­formamides matches well with the atom economy and the sustainable development intention. Nevertheless, developing a noble-free metal catalyst under mild reaction conditions is desirable and challenging. Herein, a caged metal-organic framework (MOFs) [H2N(CH3)2]2{[Ni3(µ3-O)(XN)(BDC)3]·6DMF}n (1) (XN = 6″-(pyridin-4-yl)-4,2″:4″,4″'-terpyridine), H2BDC = terephthalic acid) is harvested, presenting high thermal and chemical stabilities. Catalytic investigation reveals that 1 as a renewable noble-free MOFs catalyst can catalyze the CO2 reduction conversion with aromatic amines tolerated by broad functional groups at least ten times, resulting in various formamides in excellent yields and selectivity under the mildest reaction system (room temperature and 1 bar CO2). Density functional theory (DFT) theoretical studies disclose the applicable reaction path, in which the CO2 hydrosilylation process is initiated by the [Ni3] cluster interaction with CO2 via η2-C, O coordination mode. This work may open up an avenue to seek high-efficiency noble-free catalysts in CO2 chemical reduction into high value-added chemicals.