Zeolitic Imidazolate Framework Research Articles

Synthesis, Characterization, Density Functional Theory Study, Antibacterial Activity and Molecular Docking of Zeolitic Imidazolate Framework‐8

ABSTRACTIn this study, Zeolitic Imidazolate Framework‐8 (ZIF‐8) nanomaterials were synthesized using a co‐precipitation one‐pot method that uses ethanol, methanol, and water as solvents for the precursors (2‐methylimidazole and Zinc nitrate hexahydrate), resulting in yields of 66.77%, 73.14%, and 68.12%, respectively. The as‐synthesized ZIF‐8 nanomaterials were thoroughly characterized by X‐ray diffraction analysis, transmission electron microscopy, ultraviolet–visible spectroscopy, and Fourier‐transform infrared spectroscopy. The X‐ray diffraction analysis showed that the crystallite size of ethanol‐based ZIF‐8 (24.76 ± 1.67 nm) was smaller than those synthesized in water (26.92 ± 1.89 nm) and methanol (31.39 ± 1.03 nm). However, methanol‐based ZIF‐8 exhibited lower crystallinity (85.93%) than water‐based ZIF‐8 (91.48%) and ethanol‐based ZIF‐8 (92.71%). Zeta potential studies revealed that ethanol‐based ZIF‐8 had a larger surface charge (+37 mV) than water‐based ZIF‐8 (+35 mV) or methanol‐based ZIF‐8 (+24 mV). Transmission electron microscopy analysis confirmed particle sizes of 54.35 ± 2.11 nm for ethanol‐based ZIF‐8, 57.91 ± 2.26 nm for water‐based ZIF‐8, and 63.25 ± 4.12 nm for methanol‐based ZIF‐8. Thermogravimetric analysis indicated thermal stability up to 800 °C, with mass losses of 55.98% for ethanol‐ZIF‐8, 50.12% for water‐based ZIF‐8, and 65.36% for methanol‐based ZIF‐8 by 600 °C. In antibacterial studies, water‐based ZIF‐8 exhibited the largest zone of growth inhibition (17.30 ± 0.26 mm) against Escherichia coli compared to ethanol‐based ZIF‐8 (15.57 ± 0.32 mm) and methanol‐based ZIF‐8 (14.70 ± 0.20 mm). Pearson's correlation study revealed that zeta potential, crystallinity, and antibacterial activity are positively related. Furthermore, water‐based ZIF‐8, with a minimum inhibitory concentration of 50 μg/100 μL, confirmed evident cell membrane disruption. Molecular docking experiments revealed ZIF‐8's significant binding affinity for the E. coli protein 5AZC, supporting its robust antibacterial activity.

Pore Structure Modulation in Kirigamic Zeolitic Imidazolate Framework

Paper crafts, such as origami and kirigami, have become an interdisciplinary research theme transportable from art to science, and further to engineering. Kirigami‐inspired architectural design strategies allow the establishment of three‐dimensional (3D) mechanical linkages with unprecedented mechanical properties. Herein, we report a crystalline zeolitic imidazolate framework (ZIF), displaying folding mechanics based on a kirigami tessellation, originated from the double‐corrugation surface (DCS) pattern. Pressure‐ and guest‐induced responses demonstrate the kirigami mechanism of the ZIF, wherein imidazolate linkers act as hinges, controlling pore dimensionality, resembling the check valve‐adapted mechanical manifold. This discovery of the kirigami tessellation inside a flexible ZIF reveals foldable mechanics at the molecular level.

Pore Structure Modulation in Kirigamic Zeolitic Imidazolate Framework.

Paper crafts, such as origami and kirigami, have become an interdisciplinary research theme transportable from art to science, and further to engineering. Kirigami-inspired architectural design strategies allow the establishment of three-dimensional (3D) mechanical linkages with unprecedented mechanical properties. Herein, we report a crystalline zeolitic imidazolate framework (ZIF), displaying folding mechanics based on a kirigami tessellation, originated from the double-corrugation surface (DCS) pattern. Pressure- and guest-induced responses demonstrate the kirigami mechanism of the ZIF, wherein imidazolate linkers act as hinges, controlling pore dimensionality, resembling the check valve-adapted mechanical manifold. This discovery of the kirigami tessellation inside a flexible ZIF reveals foldable mechanics at the molecular level.

Cascade-catalysed nanocarrier degradation for regulating metabolism homeostasis and enhancing drug penetration on breast cancer.

The abnormal structure of tumor vascular seriously hinders the delivery and deep penetration of drug in tumor therapy. Herein, an integrated and tumor microenvironment (TME)-responsive nanocarrier is designed, which can dilate vessle and improve the drug penetration by in situ releasing nitric oxide (NO). Briefly, S-nitroso-glutathione (GSNO) and curcumin (Cur) were encapsulatd into the Cu-doped zeolite imidazole framework-8 (Cu-ZIF-8) and modified with hyaluronic acid. The nanocarrier degradation in the weakly acidic of TME releases Cu2+, then deplete overexpressed intratumourally glutathione and transformed into Cu+, thus disrupting the balance between nicotinamide adenine dinucleotide phosphate and flavin adenine dinucleotide (NADPH/FAD) during the metabolism homeostasis of tumor. The Cu+ can generate highly toxic hydroxyl radical through the Fenton-like reaction, enhancing the chemodynamic therapeutic effect. In addition, Cu+ also decomposes GSNO to release NO by ionic reduction, leading to vasodilation and increased vascular permeability, significantly promoting the deep penetration of Cur in tumor. Afterwards, the orderly operation of cell cycle is disrupted and arrested in the S-phase to induce tumor cell apoptosis. Deep-hypothermia potentiated 2D/3D fluorescence imaging demonstrated nanocarrier regulated endogenous metabolism homeostasis of tumor. The cascade-catalysed multifunctional nanocarrier provides an approach to treat orthotopic tumor.

Research Progress in Enhancing Proton Conductivity of Sulfonated Aromatic Polymers with ZIFs for Fuel Cell Applications

The escalating global temperatures and their adverse effects underscore the growing imperative for the widespread adoption of clean fuels, notably hydrogen. Proton Exchange Membrane Fuel Cells (PEMFC) emerge as a pivotal green energy technology, facilitating electricity and water generation. The optimization of PEMFC efficiency hinges on the judicious selection and fabrication of polymer membranes. Within innovative materials, Zeolitic Imidazolate Frameworks (ZIFs) represent a novel subclass within the expansive family of Metal-Organic Frameworks (MOFs). ZIFs exhibit promising potential in PEMFCs, owing to their distinctive properties such as a substantial contact surface, inherent porosity, and a sizable pore volume. This comprehensive review delves into composite membranes featuring ZIFs, shedding light on their chemical and thermal attributes. Additionally, the exploration extends to elucidating the diverse applications of ZIF compounds, accompanied by an in-depth discussion of selected chemical and thermal properties inherent to ZIF compounds. Incorporating ZIFs into various polymers yielded intriguing outcomes, demonstrating a notable enhancement in proton conductivity. The compilation of this review aims to provide researchers with foundational insights into the realm of ZIFs, serving as a valuable resource for future investigations and advancements in the field.

Impact of Ligand Concentration on the Properties of Nucleic-Acid-Encapsulated MOFs and Inflammation Modulation in Prostate Cancer Cells.

The zeolitic imidazolate framework (ZIF) is one of the most explored metal-organic-framework-based systems for nucleic acid delivery to cancer cells. Current nucleic acid delivery tools exhibit several drawbacks, such as high manufacturing costs, endosomal entrapment, toxicity, and immunogenicity. However, the biomimetic mineralization of Zn-based ZIFs offers a low-cost and facile encapsulation of nucleic acids at room temperature in aqueous conditions. The efficiency of nucleic acid delivery and its subsequent impact on inflammation in cells are influenced by the physicochemical properties of the material. The imidazole content determines the formation and crystallinity of ZIF, and an optimal ratio ensures the formation of well-defined and highly crystalline structures. In this study, a series of siRNA-encapsulated ZIFs (siRNA@ZIF) were systematically prepared by varying ligand-to-metal (L/M) molar ratios. Our study demonstrates that variations in ligand concentrations influence the crystalline structures, particle size, and shape of siRNA@ZIF particles. At low L/M, two-dimensional siRNA@ZIF particles form with a size of 1 μm. As the L/M ratio increases gradually, the particle size decreases, resulting in three-dimensional particles ∼200 nm in size. We also observed better stability of siRNA@ZIF in water prepared using high L/M values and time-dependent cellular uptake by the cells. Additionally, no significant impact of the biocomposites on inflammation was found, indicating the lack of an unwanted immune response and nonimmunotoxic nature over longer periods (96 h). These findings highlight the necessity of fine-tuning ligand concentrations and synthesis chemistry in designing efficient and optimal ZIF-based systems as versatile delivery platforms for nucleic acids.

Carboplatin-loaded zeolitic imidazolate framework-8: Induction of antiproliferative activity and apoptosis in breast cancer cell.

The challenge with breast cancer is its ongoing high prevalence and difficulties in early detection and access to effective care. A solution lies in creating tailored metal-organic frameworks to encapsulate anticancer drugs, enabling precise and targeted treatment with less adverse effects and improved effectiveness. Zeolitic imidazolate framework-8 (ZIF-8) and carboplatin (CP)-loaded ZIF-8 were synthesized and characterized using various analytical techniques. High Resolution-transmission electron microscopy of ZIF-8 and CP@ZIF-8 indicates that the particles had a spherical shape and were nanosized. The drug release rate of CP is 98% under an acidic medium (pH 5.5) because of the dissolution of ZIF-8 into its coordinating ions, whereas 35% in a physiological medium (pH 7.4) with the addition of CP, the high porosity, and pore diameter of ZIF-8 decrease from 1243 to 1041m2/g. Breast cancer MCF-7 cells were shown greater IC50 in CP@ZIF-8 (15.01±3.03µg/mL) than free CP (34.98±4.25µg/mL) in an in vitro cytotoxicity assessment. The cytotoxicity of the CP@ZIF-8 against MCF-7 cells was studied using the methylthiazolyldiphenyl-tetrazolium bromide method. The morphological changes were examined using fluorescent staining (acridine orange-ethidium bromide and Hoechst 33258) methods. The comet assay assessed the DNA fragmentation (single-cell gel electrophoresis). The results from the study revealed that CP@ZIF-8 can be used in the treatment of breast cancer.

Surface Coating of ZIF-8 Nanoparticles with Polyacrylic Acid: A Facile Approach to Enhance Chemical Stability for Biomedical Applications.

Nanoparticles of zeolitic imidazole framework-8 (ZIF-8 NPs), which are the subclass of metal-organic frameworks consisting of Zn ion and 2-methylimidazole, have been identified as promising drug carriers since their large microporous structure is suited for encapsulating hydrophobic drug molecules. However, one of the limitations of ZIF-8 NPs is their low stability in physiological solutions, especially in the presence of water and phosphate anions. These molecules can interact with the coordinatively unsaturated Zn sites at the external surface to induce the degradation of ZIF-8 NPs. In this study, herein a facile approach is reported to enhance the chemical stability of ZIF-8 NPs by surface coating with polyacrylic acid (PAA). The PAA-coated ZIF-8 (PAA-ZIF-8) NPs are prepared by mixing ZIF-8 NPs and PAA in water. PAA coating inhibits the degradation of ZIF-8 NPs in water as well as phosphate-buffered saline over 6 days, which seems to be due to the coordination of carboxyl groups of PAA to the reactive Zn sites. Furthermore, the PAA-ZIF-8 NPs loaded with the anticancer drug doxorubicin (Dox) show cytotoxicity in human colon cancer cells. These results clearly show the feasibility of the PAA coating approach to improve the chemical stability of ZIF-8 NPs without impairing their drug delivery capability.

Magnetic 3D macroporous MOF oriented urinary exosome metabolomics for early diagnosis of bladder cancer

Bladder cancer (BCa) exhibits the escalating incidence and mortality due to the untimely and inaccurate early diagnosis. Urinary exosome metabolites, carrying critical tumor cell information and directly related to bladder, emerge as promising non-invasive diagnostic biomarkers of BCa. Herein, the magnetic 3D ordered macroporous zeolitic imidazolate framework-8 (magMZIF-8) is synthesized and used for efficient urinary exosome isolation. Notably, beyond retaining the single crystals and micropores of conventional ZIF-8, MZIF-8 is further enhanced with highly oriented and ordered macropores (150 nm) and the large specific surface area (973 m2·g–1), which could enable the high purity and yield separation of exosomes via leveraging the combination of size exclusion, affinity, and electrostatic interactions between magMZIF-8 and the surfaces of exosome. Furthermore, the magnetic and hydrophilic properties of magMZIF-8 will further simplify the process and enhance the efficiency of separation. After conditional optimization, a 50 mL of urine is sufficient for exosome metabolomics analysis, and the time for isolating exosomes from 42 urine samples was 2 hours only. Incorporating machine learning algorithms with LC-MS/MS analysis of the metabolic patterns obtained from isolated exosomes, early-stage BCa patients were differentiated from healthy controls, with area under the curve (AUC) value of 0.844–0.9970 in the training set and 0.875-1.00 in the test set, signifying its potential as a reliable diagnostic tool. This study offers a promising approach for the non-invasive and efficient diagnosis of BCa on a large scale via exosome metabolomics.Graphical

Inhibition of the Germination of Root Parasitic Plants by Zeolitic Imidazolate Framework-8.

Crystalline ZIF-8 (C-ZIF-8) and amorphous ZIF-8 (Am-ZIF-8) were prepared and investigated to control the germination of Striga hermonthica, a root parasitic plant, which threatens cereal crops production particularly in sub-Saharan Africa. We have demonstrated that Am-ZIF-8 shows a better performance than C-ZIF-8 in inhibiting Striga seeds germination. This efficient performance of Am-ZIF-8 materials can be attributed to the incomplete deprotonation of 2 methylimidazole (2MIM) during amorphization, leading to the presence of unsaturated Zn-N coordination with the uncoordinated -NH groups available to undergo hydrogen bonding with the strigolactone analog GR24 forming a more stable Am-ZIF-8⋅⋅⋅GR24 hydrogen bonded network. We further established that application of ZIF-8 materials generally has no adverse effects on the growth and quality of rice crops.

Metal organic framework derived heteroatom doped porous carbon nanocubes enable efficient charge storage in a lithium-ion capacitor

Lithium-ion capacitors (LICs) are regarded as one of the promising technologies towards realizing energy & power dense energy storage systems. However, their energy densities at higher power densities are still limited due to the discrepancy between electrode kinetics of capacitor-like cathode and battery-like anode. Developing carbon materials with well-defined structures, porosity to match the chemical kinetics between electrodes are the major challenges to overcome. In the present work, we have devised a strategy to fabricate S, N dual-doped porous carbon nanocubes (S, N-PCNs) using zeolitic imidazole framework (ZIF)-8 precursors, and employed the PCNs as anode material in LICs. With its well-defined structure, hierarchical porous nature, and abundant heteroatom presence (1.9 % S, 16.2 % N), the pre-lithiated S, N-PCNs based anode has offered a greatly improved reversible storage capacity of ∼930 mAh g−1 at 0.1 A g−1 along with an impressive rate capability and cycling life. When S, N-PCNs anode is paired with activated carbon cathode, the 4 V dual-carbon LIC yields an energy density as high as 120.24 Wh kg−1 and 10.2 kW kg−1 of power density with a good cycle stability of 90.6 % after 5000 charge-discharge cycles. This work would open new scopes of exploring metal-organic framework derived heteroatom-doped porous carbons to make metal-ion capacitors more efficient.

Composition-optimized NiGa-LDH on MOF-derived and cobalt-nanoparticles-embedded carbon flakes for enhanced potassium-ion storage

Layered double hydroxides (LDHs), renowned for their distinct nanostructures, efficient ion channels, and high specific capacitance, are promising electrode materials for supercapacitors (SCs). However, commercial applications remain limited due to constraints in the rate capabilities and cycling. The synergistic effects of the composites can be leveraged by pairing LDHs with carbon materials to enhance the conductivity for better SC characteristics. Herein, flaky Zeolitic Imidazolate Framework(ZIF)-67 is deposited on carbon cloth and calcined to produce the MOF-derived composite of carbon nanosheet-embedded nano-cobalt particles (CPEC) on the surface of the carbon cloth. Afterward, NiGa-LDH with a controllable Ni to Ga ratio is synthesized on the CPEC to form a flower-like hierarchical nanostructure NiGa-LDH/CPEC@CC. Co nanoparticles act as nucleation sites for cohesive formation within the carbon cloth framework. Ni2Ga1-LDH/CPEC@CC has the best properties, such as a specific capacitance of 729.6F g−1 at 1 mA cm−2 and 97.3 % capacitance retention at 2 mA cm−2. The asymmetric supercapacitor (ASC) consisting of Ni2Ga1-LDH/CPEC@CC//AC has an excellent energy density of 83.96 Wh kg−1 with a power density of 80 W kg−1. Density-functional theory (DFT) calculations of Ni2Ga1-LDH/CPEC@CC affirm a potassium ion adsorption energy of −2.127 eV and density of state (DOS) near the Fermi level. The study imparts theoretical and technical knowledge about the design of complex nanostructures from MOF precursors.

Electrophoretic deposition of novel antibacterial and biocompatible polydopamine and ZIF-8 hybrid composite coating on anodized Ti-6Al-4V alloy with silane primary substrate

Production of biocompatible and corrosion resistance dental implant is a requirement in the modern dental science. In this work, the Ti-6Al-4V was used alloy for the dental implant application that has investigated to make it more corrosion resistive and antibacterial with electrophoretic deposition of silane precursor solution that made of acidic solution of tetraethyl orthosilicate (TEOS) and methyl three ethoxy silane (MTES). The optimized silane coating has been achieved with 30 V, 30 min and at 100 °C ramped annealing by comparison of Taffel analysis and electrochemical impedance spectroscopy (EIS). Also, a new nanocomposite including polydopamine (PDA) and zeolite imidazole frame work composed from Zn (NO3)2 .6H2O and 2-methylimidazole (ZIF-8) that name PDA@ZIF-8 has been used as biocompatible and corrosion resistance amplifier to the precursor solution and used in the multilayer deposition process. The morphology analysis including atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM) imaging and the obtained parameters show that coating has appropriate roughness that could increase the bounding of implant. A good adhesion strength has been determined for the two-layers silane coating with PDA@ZIF-8 according to the pull- off test. On the other hand, the antibacterial analysis indicate that the coating is an effective material for S. mutans and E. coli reduction that is another criterion for the dental implant materials. The results was introduced the coated Ti-6Al-4V could be used as corrosion resistive and antibacterial dental implant material.

Eco-friendly synthesized zeolitic imidazolate framework-8 enables one-step cerium recovery from water

Eco-friendly synthesized zeolitic imidazolate framework-8 enables one-step cerium recovery from water

Pine sawdust immobilized zeolitic imidazolate framework-67 derived magnetic composites: An efficient and recycable adsorbent for norfloxacin removal

Pine sawdust immobilized zeolitic imidazolate framework-67 derived magnetic composites: An efficient and recycable adsorbent for norfloxacin removal

Wood meet MOFs: Facile, green, and highly selective adsorbent for textile wastewater

Owing to their unique physicochemical features, ionic liquids (ILs) are extensively utilized to dissolve cellulose for the preparation of regenerated cellulose fibers (RCFs) in the textile industry. However, Cu2+ is introduced during the cellulose dissolution process and gradually accumulates, seriously affecting the RCF performance and IL recovery. Herein, to achieve an efficient and selective adsorption of Cu2+ from ILs aqueous solutions, a facile and green method based on the in situ growth of zeolitic imidazolate framework-67 in wood hydrogels (ZIF-67@WH) is presented. The morphology, functional groups, crystallinity, thermal stability, and pore structure of the resulting ZIF-67@WH were investigated using various characterization techniques, and the adsorption selectivity, adsorption thermodynamics, adsorption kinetics, and recoverability were examined in depth by performing batch experiments. The ZIF-67@WH exhibits high adsorption selectivity for Cu2+ and ILs with adsorption ratios of 92.8 % and 2.2 %, respectively. The selective adsorption mechanism was elucidated by means of FT-IR, XPS, DFT, and MD. As the key for the selective adsorption, the N site in ZIF-67 dramatically promotes the coordination with Cu2+, while the adsorption for ILs mainly occurs via hydrogen bonding and van der Waals interactions with adsorption energies of –80.61 and –35.33 kcal/mol, respectively. The results demonstrate that this approach constitutes a feasible technique for the efficient separation of Cu2+ and ILs in the textile industry.

Ruthenium Phosphide Nanoclusters Dispersed on Zeolitic Imidazolate Framework-8 and Encapsulated in N,P-Codoped Carbon as Electrocatalysts for the Hydrogen Evolution Reaction

Ruthenium Phosphide Nanoclusters Dispersed on Zeolitic Imidazolate Framework-8 and Encapsulated in N,P-Codoped Carbon as Electrocatalysts for the Hydrogen Evolution Reaction

Compositional Complexity of Metal-Organic Frameworks with Programmable Spatial Arrangement of Multi-Metallic Components.

The components and structures of metal-organic frameworks (MOFs) are critical two factors that influence their properties and prospective applications. Moreover, the construction of complex MOFs integrating multiple components holds promise to achieve MOFs with unique properties. However, constructing complex MOFs with an intended 3D spatial arrangement of the multiple components remains underdeveloped. Herein, a systematic approach is reported for designing and constructing complex MOFs featuring multi-metallic components with programmed 3D spatial distributions. Syringe pumps with programmed injection rates are employed to feed the intended amounts of multi-metallic components into a reactor at specific time points. By controlling the quantities of components present in the reactor, their incorporation within MOFs is carefully managed, eventually achieving the intended spatial arrangement of multi-metallic components within MOFs. This approach is successfully applied to constructing numerous bimetallic and trimetallic zeolitic imidazolate frameworks with programmed spatial distributions of Zn2+, Co2+, Cu2+, and/or Ni2+, with varied combinations, quantities, sequences, and numbers. This method is also suitable for fabricating the bimetallic MIL-88B, proving its applicability to many MOFs. Using this method, precise control over multiple components with intended and complex spatial distributions can be attained, enabling the construction of special MOFs with tailored properties and functions.

Hierarchical core-shell ZIF-11@ZIF-8 composite nanocatalyst for high-yield simultaneous transesterification-esterifications of sunflower oil to produce biodiesel

Decreasing the mass transfer resistance is a promising technique to prepare an efficient catalyst for improving biomass macromolecules conversion in biodiesel production. In this study, hierarchical core–shell composite nanocatalysts were prepared through a solvothermal technique using zeolitic imidazolate framework-8 (ZIF-8) and ZIF-11 metal–organic frameworks (MOFs). The nanocatalysts were characterized by XRD, FT-IR, BET, FE-SEM, EDS, XPS, TEM, NH3-TPD, and CO2-TPD analyses. The results showed high crystallinity, high surface area (1446.86 m2/g), high pore volume (0.65 cm3 g−1), and mesoscale pore size (2.37 nm). Furthermore, TEM images confirmed the formation of core–shell structure for the composites. The catalytic activity was evaluated in the transesterification of sunflower oil at different operating conditions. The highest biodiesel yield (96.4 %) and full free fatty acid (FFA) conversion were obtained over the ZIF-11@ZIF-8 nanocatalyst at the optimum operating conditions: 120 °C, catalyst concentration of 8 wt%, methanol to oil ratio of 40:1, and 10 h. The ZIF-11@ZIF-8 nanocatalyst showed high thermal and chemical stability after several sequence cycles, leading to high reusability.

Ligand engineering enhances (photo) electrocatalytic activity and stability of zeolitic imidazolate frameworks via in-situ surface reconstruction

The current limitations in utilizing metal-organic frameworks for (photo)electrochemical applications stem from their diminished electrochemical stability. In our study, we illustrate a method to bolster the activity and stability of (photo)electrocatalytically active metal-organic frameworks through ligand engineering. We synthesize four distinct mixed-ligand versions of zeolitic imidazolate framework-67, and conduct a comprehensive investigation into the structural evolution and self-reconstruction during electrocatalytic oxygen evolution reactions. In contrast to the conventional single-ligand ZIF, where the framework undergoes a complete transformation into CoOOH via a stepwise oxidation, the ligand-engineered zeolitic imidazolate frameworks manage to preserve the fundamental framework structure by in-situ forming a protective cobalt (oxy)hydroxide layer on the surface. This surface reconstruction facilitates both conductivity and catalytic activity by one order of magnitude and considerably enhances the (photo)electrochemical stability. This work highlights the vital role of ligand engineering for designing advanced and stable metal-organic frameworks for photo- and electrocatalysis.