Zinc Metal-organic Framework Research Articles

Fabrication of sponge-like Zn-dpNDI-MOF film optical waveguides for study of improved optical gas adsorbility and kinetics

A sponge-like zinc metal-organic framework film, [Zn2(TpA)2(dpNDI)]n (Zn-dpNDI-MOF, where, TpA = terephthalic acid; dpNDI = N,N′-dipyridylnaphthalenediimide), was prepared on a tin-doped glass optical waveguide (OWG) substrate using a solvothermal method. The effect of the solvothermal growth time on the morphology, optical characteristics, and gas adsorption properties of the Zn-dpNDI-MOF film was investigated. The gas adsorption sensitivity was assessed by comparing the growth of Zn-dpNDI-MOF film OWGs under in situ and UV-light illumination conditions. The results revealed that the Zn-dpNDI-MOF films were optically transparent and exhibited a sponge-like structure after 20 h of continuous growth. Additionally, they demonstrated a higher adsorption response to xylene and ethylenediamine (EDA) gases because of the intrinsic electron deficiencies of the framework and the higher molar refractive indices and dipoles of xylene and EDA compared to other gases. Within the xylene concentration range of 10 ppb–1000 ppm, the OWG film exhibited a fast, improved response. In the static gas adsorption process performed at 283–313 K, the xylene adsorption behaviour of the Zn-dpNDI-MOF film followed a pseudo-second-order (PSO) kinetic model. Within 0–60 min of adsorption time, the amount of xylene gas adsorbed on the unit surface was shows as high as 6.21 μg cm−2. Compared to the in situ grown film, the Zn-dpNDI-MOF film OWGs showed higher sensitivity to xylene gas owing to their higher refractive indices.

Single-atom iron boosts electrochemiluminescence for ultrasensitive carcinoembryonic antigen detection.

Asimple and ultrasensitive sandwich-type electrochemiluminescence (ECL) immunosensor has been developedusing porous three-dimensional gold nanoparticles (Au NPs) iron(Fe)-zinc(Zn) metal-organic frameworks (Au NPs-FeZn-MOFs@luminol) as high-efficiency ECL signal probes with Fe single-atom catalysts (SACs) (Fe-N-C SACs) as potentially advanced coreaction accelerators and dissolved oxygen as a coreaction agent to realize an H2O2-free amplification method for detecting carcinoembryonic antigen (CEA). The cathodic ECL of luminol, which was usually negligible, increased first. Because the Fe-N-C SACs exhibited an outstanding catalytic performance and a unique electronic structure, different reactive oxygen species (ROS) were generated via the oxygen reduction reaction. ROS oxidized the luminol anions to luminol anion radicals, preventing the time-consuming luminol electrochemical oxidation. Furthermore, the luminol anion radicals generated in situ reacted with ROS to produce potent cathodic ECL emissions. The immunosensor exhibited favorable analytical accuracy (detection range: 0.1 pg mL-1-80 ng mL-1), and its detection limit for serum samples was 0.031 pg mL-1 (S/N = 3). Consequently, the proposed strategy offers a new approach for early screening of CEA.

Torsional flexibility in zinc-benzenedicarboxylate metal-organic frameworks.

We explore the role and nature of torsional flexibility of carboxylate-benzene links in the structural chemistry of metal-organic frameworks (MOFs) based on Zn and benzenedicarboxlyate (bdc) linkers. A particular motivation is to understand the extent to which such flexibility is important in stabilising the unusual topologically aperiodic phase known as TRUMOF-1. We compare the torsion angle distributions of TRUMOF-1 models with those for crystalline Zn/1,3-bdc MOFs, including a number of new materials whose structures we report here. We find that both periodic and aperiodic Zn/1,3-bdc MOFs sample a similar range of torsion angles, and hence the formation of TRUMOF-1 does not require any additional flexibility beyond that already evident in chemically-related crystalline phases. Comparison with Zn/1,4-bdc MOFs does show, however, that the lower symmetry of the 1,3-bdc linker allows access to a broader range of torsion angles, reflecting a greater flexibility of this linker.

Multifunctional nanocomposites mediated novel hydrogel for diabetic wound repair.

The regeneration and repair of diabetic wounds, especially those including bacterial infection, have always been difficult and challenging using current treatment. Herein, an effective strategy is reported for constructing glucose-responsive functional hydrogels using nanocomposites as nodes. In fact, tannic acid (TA)-modified ceria nanocomposites (CNPs) and a zinc metal-organic framework (ZIF-8) were employed as nodes. Subsequent crosslinking with 3-acrylamidophenylboronic acid achieved functional nanocomposite-hydrogels (TA@CN gel, TA@ZMG gel) by radical-mediated polymerization. Compared with a simple physically mixed hydrogel system, the mechanical properties of TA@CN gel and TA@ZMG gel are significantly enhanced due to the intervention of the nanocomposite nodes. In addition, this kind of nanocomposite hydrogel can realize the programmed loading of drugs and release of drugs in response to glucose/PH, to coordinate and promote its application in the regeneration and repair of diabetic wounds and infected diabetic wounds. Specifically, TA@CN gel can remove reactive oxygen species and generate oxygen through its various enzymatic activities. At the same time, it can effectively promote neovascularization, thus promoting the regeneration and repair of diabetic wounds. Furthermore, glucose oxidase-loaded TA@ZMG gel exhibits glucose response and pH-regulating functions, triggering programmed metformin (Met) release by degrading the metal-organic framework (MOF) backbone. It also exhibited additional synergistic effects of antibacterial activity, hair regeneration and systemic blood glucose regulation, which make it suitable for the repair of more complex infected diabetic wounds. Overall, this novel nanocomposite-mediated hydrogel holds great potential as a biomaterial for the healing of chronic diabetic wounds, opening up new avenues for further biomedical applications.

Magnetized cubic zinc MOFs for efficient removal of hazardous cationic and anionic dyes in aqueous solutions.

A significant amount of dye runoff and aqueous waste are released from the manufacturing process of dyes with intense and permanent colors, which are undesirable from a cultural and ecological aspect. In this paper, we present a green, simple, low-effort, and energy-efficient method of creating magnetized cubic Zn-MOFs for the adsorption and elimination of various organic dyes. Magnetic iron oxide materials with a hierarchical structure were loaded and doped into cubic zinc metal-organic frameworks (MDLZ). High magnetic characteristics, chemical stability, minimal toxicity, and ease of removing various dyes from aqueous effluents are all exhibited by the developed MDLZ adsorbent. To assess MDLZ's capacity to adsorb organic dyes from an aqueous solution, organic dyes such as Crystal Violet (CV), Neutral Red (NR), and Congo Red (CR) were used as model materials. Many adsorption factors were examined, including temperature, pH, contact time, initial concentration, and adsorbent dosage. Under optimal elimination circumstances, MDLZ was utilized to evaluate the kinetic, thermodynamic, and isotherm models for the adsorption of CR, NR, and CV dyes. The adsorption capacity (q m) of the MDLZ adsorbent at 25 °C was 39.37 mg g-1 for CV, 239.81 mg g-1 for CR, and 321.54 mg g-1 for NR, which is significantly higher than those of other adsorbents reported. The magnetized nanocubes' large surface area and uniform micropores enabled them to eliminate a large number of organic dyes from wastewater effectively, and their strong adsorption capability persisted even after four reuse cycles. The microporous MLDZ adsorbent offers a simple and effective method for handling industrial effluents and filtration of water.

Exfoliation of a metal-organic framework enabled by post-synthetic cleavage of a dipyridyl dianthracene ligand.

The synthetic tunability and porosity of two-dimensional (2D) metal-organic frameworks (MOFs) renders them a promising class of materials for ultrathin and nanoscale applications. Conductive 2D MOFs are of particular interest for applications in nanoelectronics, chemo-sensing, and memory storage. However, the lack of covalency along the stacking axis typically leads to poor crystallinity in 2D MOFs, limiting structural analysis and precluding exfoliation. One strategy to improve crystal growth is to increase order along the stacking direction. Here, we demonstrate the synthesis of mechanically exfoliatable macroscopic crystals of a 2D zinc MOF by selective dimensional reduction of a 3D zinc MOF bearing a dianthracene (diAn) ligand along the stacking axis. The diAn ligand, a thermally cleavable analogue of 4,4'-bipyridine, is synthesized by the direct functionalization of dianthraldehyde in a novel "dianthracene-first" approach. This work presents a new strategy for the growth of macroscopic crystals of 2D materials while introducing the functionalization of dianthraldehyde as a means to access new stimuli-responsive ligands.

Highly enhanced cationic dye adsorption from water by nitro-functionalized Zn-MOF nano/microparticles and biomolecular binder for improving the reusability

Zinc-metal organic frameworks (Zn-MOFs) of phthalic acid (ZnPA) and nitro-phthalic acid (ZnNPA) microcrystalline particles were fabricated and utilized for the removal of organic cationic dyes (crystal violet (CV), methylene blue...

A magnetic adsorbent of nitrogen-doped graphene quantum dots, zinc metal-organic framework and molecularly imprinted polymer to extract phenylureas

A highly selective composite nano-sorbent was designed and fabricated for the extraction and enrichment of phenylureas. The nano-sorbent was composed of nitrogen-doped graphene quantum dots (N-GQDs), a zinc metal-organic framework (IRMOF-1) and magnetite nanoparticles incorporated in molecularly imprinted polymer (MIP). The fabricated nano-sorbent was characterized and applied to extract and enrich three phenylureas in a dispersive magnetic solid-phase extraction (d-MSPE) process. The developed method was highly sensitive and detected the target phenylureas at trace levels. The linear range was from 1.0 to 150 µg L−1 and the limit of detection was 1.0 µg L−1. The large specific surface area of the nano-sorbent produced highly efficient adsorption. When applied to extract phenylureas in vegetable samples, recoveries were in the range of 80.2–95.8% with relative standard deviations lower than 8.0%. The developed nano-sorbent not only exhibited highly selective and efficient extraction but also good stability which can be reused four times, and ease of fabrication. The developed strategy can also be modified for the extraction and determination of other organic compounds in various complex samples.

Tuning Coordination Structures of Zn Sites Through Symmetry-Breaking Accelerates Electrocatalysis.

Manipulating the coordination environment of individual active sites in a precise manner remains an important challenge in electrocatalytic reactions. Herein, inspired by theoretical predictions, a facile procedure to synthesize a series of symmetry-breaking zinc metal-organic framework (Zn-MOF) catalysts with well-defined structures is presented. Benefiting from the optimized coordination microenvironment regulated by symmetry-breaking, Zn-N2 S2 -MOF exhibits the best performance of nitrogen (N2 ) reduction reaction (NRR) with NH3 yield rate of 25.07±1.57µgh-1 cm-2 and Faradaic efficiency of 44.57±2.79% compared with reported Zn-based NRR catalysts. X-ray absorption near-edge structure shows that the symmetry-breaking distorts the coordination environment and modulates the delocalized electrons around the Zn sites, which favors the formation of unpaired low-valence Znδ+ , thereby facilitating the adsorption/activation of N2 . Theoretical calculations elucidate that low-valence Znδ+ in Zn-N2 S2 -MOF can effectively lower the energy barrier of potential determining step, promoting the kinetics and boosting the NRR activity. This work highlights the relationship between the precise coordination environment of metal sites and the catalytic activity, which offers insightful guidance for rationally designing high-efficiency electrocatalysts.

Two Stable Bifunctional Zinc Metal-Organic Frameworks with Luminescence Detection of Antibiotics and Proton Conduction.

Functionalized crystalline solids based on metal-organic frameworks (MOFs) enable efficient luminescence detection and high proton conductivity, making them crucial in the realms of environmental monitoring and clean energy. Here, two structurally and functionally distinct zinc-based MOFs, [Zn(TTDPa)(bodca)]·H2O (1) and [Zn(TTDPb)(bodca)]·H2O (2), were successfully designed and synthesized using 3,6-di(pyridin-4-yl)thieno[3,2-b]thiophene (TTDPa) and 2,5-di(pyridin-4-yl)thieno[3,2-b]thiophene (TTDPb) as ligands, in the presence of bicyclo[2.2.2]octane-1,4-dicarboxylic acid (H2bodca). Both 1 and 2 display a three-dimensional (3D) structure with 5-fold interpenetration, and notably, 2 forms a larger one-dimensional pore measuring 17.16 × 10.81 Å2 in size. Fluorescence experiments demonstrate that 1 and 2 can function as luminescent sensors for nitrofurantoin (NFT) and nitrofurazone (NFZ) with low detection limits, remarkable selectivity, and good recyclability. A comprehensive analysis was conducted to investigate the differing sensing effects of compounds 1 and 2 and to explore potential sensing mechanisms. Additionally, at 328 K and 98% relative humidity, 1 and 2 exhibit proton conductivity values of 2.13 × 10-3 and 4.91 × 10-3 S cm-1, respectively, making them suitable proton-conducting materials. Hence, the integration of luminescent sensing and proton conductivity in monophasic 3D Zn-MOFs holds significant potential for application in intelligent multitasking devices.

A two-fold interpenetrated Zn(II) organic framework based on mixed ligands: Synthesis, crystal structure, and properties

A new zinc(II) metal organic framework has been obtained from the solvothermal assembly of 1,3,5-benzene tricarboxylate and 1,3-bis(imidazole)propane with zinc nitrate in DMAc–H2O (DMAc is N,N-dimethylacetamide), namely {[Zn2 (μ2-OH)(1,3-BIP)(BTC)]·DMAc·2H2O}n (SNUT-6). The product is characterized by single-crystal and powder X-ray diffraction, infrared spectroscopy, thermogravimetric analysis, and elemental analysis. The single-crystal X-ray diffraction reveals that SNUT-6 exhibits a 3D→3D two-fold interpenetrating framework. Furthermore, SNUT-6 demonstrates a highly efficient turn-off fluorescent detection ability for aniline in methanol and shows high sensitivity with a Ksv value of 4.771 × 104 M−1. It also shows excellent photocatalytic degradation performance for a three-dye molecular model: rhodamine b, methyl orange, and methyl blue.

Bidirectional redox catalyst with rambutan-like structure for advanced lithium-sulfur battery

The lithium polysulfide (LiPSs) shuttle effect and sluggish conversion kinetics hinder the commercial viability of lithium-sulfur (Li-S) batteries. To improve the properties of Li-S batteries, it is imperative to establish efficient pathways for Li-ions transmission by constructing conductivity channels of high quality, and to expedite the conversion kinetics of LiPSs by employing catalysts of exceptional activity. In this study, we synthesized a spherical superstructure of metal–organic framework nanorods (SS-MOFNR) using a self-assembly strategy with zinc-metal–organic framework (Zn-MOF) nanoparticles, followed by carbonization to obtain the spherical superstructure of carbon nanorods (SS-CNR). Subsequently, palladium nanoparticles were synthesized through the reduction and uniformly dispersed onto SS-CNR. The hollow porous structure facilitates the efficient utilization of sulfur and ensures the rapid diffusion of Li-ions. Additionally, Pd nanoparticles exhibit significant catalytic activity, effectively adsorbing LiPSs and bidirectional catalytic conversion of sulfur species, thereby effectively suppressing the shuttle effect of LiPSs. Therefore S/Pd@SS-CNR electrode demonstrates commendable electrochemical efficacy, as evidenced by its initial specific capacity of 1627.7 mAh g−1 at 0.1C and maintaining a specific capacity of 766.2 mAh g−1 even after 600 cycles at 0.5C. Moreover, it exhibits favorable cycle stability at 2C, retaining a reversible capacity of 502.3 mAh g−1 after undergoing 1000 cycles.

Copper and Zinc Metal-Organic Frameworks with Bipyrazole Linkers Display Strong Antibacterial Activity against Both Gram+ and Gram- Bacterial Strains.

Here, we report a new synthetic protocol based on microwave-assisted synthesis (MAS) for the preparation of higher yields of zinc and copper in MOFs based on different bis(pyrazolyl)-tagged ligands ([M(BPZ)]n where M = Zn(II), Cu(II), H2BPZ = 4,4'-bipyrazole, [M(BPZ-NH2)]n where M = Zn(II), Cu(II); H2BPZ-NH2 = 3-amino-4,4'-bipyrazole, and [Mx(Me4BPZPh)] where M = Zn(II), x = 1; Cu(II), x = 2; H2Me4BPZPh = bis-4'-(3',5'-dimethyl)-pyrazolylbenzene) and, for the first time, a detailed study of their antibacterial activity, tested against Gram-negative (E. coli) and Gram-positive (S. aureus) bacteria, as representative agents of infections. The results show that all MOFs exert a broad-spectrum activity and strong efficiency in bacterial growth inhibition, with a mechanism of action based on the surface contact of MOF particles with bacterial cells through the so-called "chelation effect" and reactive oxygen species (ROS) generation, without a significant release of Zn(II) and Cu(II) ions. In addition, morphological changes were elucidated by using a scanning electron microscope (SEM) and bacterial cell damage was further confirmed by a confocal laser scanning microscopy (CLSM) test.

Solar Assisted Removal of Methylene Blue Dye from Wastewater Using Zinc-Metal Organic Framework (Zn-MOF)

Solar Assisted Removal of Methylene Blue Dye from Wastewater Using Zinc-Metal Organic Framework (Zn-MOF)

A zinc metal–organic framework with excellent water stability for effective C2H2/C2H4 separation

A zinc metal–organic framework with excellent water stability for effective C2H2/C2H4 separation

A smartphone-based visual ratiometric fluoroprobe for rapid and sensitive detection hypochlorous acid based on dual-emission metal organic frameworks

Herein, we designed/developed a mixed fluorescence system with europium metal-organic framework (EDB) and zinc metal-organic framework (ZBNB). At the 270-nm excitation wavelength, the EDB-ZBNB dually emitted at 425 and 615 nm and displayed blue solution under 365-nm UV lamp. When HOCl was fortified, the 425-nm blue emission dropped progressively, while the 615-nm red emission was relatively stable. Upon addition of ClO−, the shortened fluorescence lifetime demonstrated that the quenched 425-nm fluorescence of ZBNB was owing to the occurrence of dynamic quenching effect. Besides, amino groups are protonated in water to form -NH3+, which interact with ClO− to form hydrogen bonds, reduce the distance between -NH3+ and ClO−, produce energy transfer and result in fluorescence quenching. The ratiometric fluoroprobe provided a significant color change from blue to red, making HOCl detection visual and rapid. This fluorescent probe overcome the disadvantage of conventional redox-based fluorescent probes that can be interfered by MnO4− and other oxidants with stronger oxidizing capacity than free ClO−. Furthermore, a smartphone-based portable sensing platform was developed based on EDB-ZBNB. By using a “Thingidentify” software on smartphone, the sensing platform was used to detect HOCl in waters with a low detection limit of 28.0 nM and the fortified recoveries of 98.87–103.60%. Thus, this study provides a novel and promising platform for the detection of free ClO− in monitoring water quality.

A bioinspired fluorescent probe based on metal–organic frameworks to selectively enrich and detect amyloid-β peptide

Amyloid-β peptide (Aβ) in serum is an effective biomarker for the early diagnosis of Alzheimer's disease (AD). However, there are serious challenges to monitor subtle changes of Aβ in the blood due to its low expression and the complex interference from the environment. Inspired by the delicate structure of natural enzymes, the metal site coordination, hydrophobic microenvironment, and the size selectivity feature, herein, a fluorescent probe based on bi-ligand zinc metal–organic frameworks is designed for accurate detection of Aβ in serum. By chelating with Zn2+, the fluorescent small molecule N-(6-(benzothiazol-2-yl)pyridin-3-yl)-5-(dimethylamino)naphthalene-1-sulfonamide (BPNS) participated in the self-assembly process as one of the organic linkers to form this novel flower-shaped probe Zn-FBIFs. As proposed, the synergism of hydrophobic nature and size-exclusion effect made Zn-FBIFs can rapidly and selectively enrich Aβ and exhibit excellent anti-interference ability towards interfering proteins in serum. Then by competitively binding to Zn2+, Aβ replaced the BPNS in Zn-FBIFs and the released BPNS gave a fluorescence signal for Aβ detection. The detection limit in undiluted serum was as low as 3.22 nM and that was two orders of magnitude decreased compared with the reported detection limit by BPNS calculated in 80-fold diluted serum. The results demonstrated our proposal of the bioinspired probe is effective in significantly improving the detection accuracy and that would give new insight into the development of novel probes for trace substance detection in complex biosamples.

Effective adsorptive removal of tetracycline from aqueous solution by Zn-BTC@SBC derived from sludge:Experimental study and density functional theory (DFT) calculations

Overuse of tetracycline (TC) has caused serious damage to aquatic environment. Developing sustainable and efficient removal technologies for TC is of great significance to eliminate its ecological risks. In this study, a novel zinc metal organic framework porous biochar composite (Zn-BTC@SBC) derived from sludge was the first time synthesized and employed for adsorptive removal of TC from water.The adsorption process of TC followed the Elovich and Temkin model and the maximum capacity of Zn-BTC@SBC to adsorb TC was 125.9 mg/g. Characterization analysis demonstrated that the greater adsorption capacity of Zn-BTC@SBC was ascribed to its larger surface area, pore volume and abundant oxygen-containing functional groups. The fitting results showed that both chemisorption and physical adsorption predominated the adsorption process of TC on Zn-BTC@SBC. Further material characterization (FTIR and XPS) and density functional theory (DFT) calculations at the molecular level suggested that the good adsorption performance of Zn-BTC@SBC on TC might be due to chemisorption dominated by oxygen-containing functional groups, which included π-π conjugation, H-bonding and electrostatic interaction. And it was a spontaneous, endothermic and randomness increasing reaction. Both ion species/strength and solution pH significantly affected the adsorption capacity of Zn-BTC@SBC for TC. The natural water samples with complex composition (lake and river water) still showed 71.27–76.37 % of TC adsorbed. The used Zn-BTC@SBC was capable of maintaining its stable adsorption capacity by NaOH regeneration. This study demonstrated that Zn-BTC@SBC was a promising practicability in removal of TC and workable approach for sustainable utilization of sludge.

Electrochemical Behavior and Electrical Stability of a Needle-Shaped Zinc Metal-Organic Framework Modified Graphite Electrode

In this paper, a novel needle-shaped Zinc organic framework was formed on the surface of a functionalized graphite electrode (Zn-MOF/CE) to create a methodical alternative electrode. The characterization of the Zn-MOF modifier was investigated via XRD, FT-IR, FESEM-EDS mapping, and N2 sorption. The redox behavior of the modified electrode was examined, showing high stability and conductivity under a diffusion-controlled process as a desirable working electrode. Also, the redox process of hydroquinone, as an organic molecule model, at the surface of the modified electrode was investigated and its operation was optimized and modeled by the central composite design (CCD) method. Based on the obtained results and CCD model, the process exhibited the best performance in scan rate 560 mV/s, pH= 9.9. Moreover, the frequency domain using bode plots, and two identical electrical models were evaluated by CCD results that could be employed in stability and electrode material performance prediction.

Surface-functionalized Zinc MOFs delivering zinc ion and hydrogen sulfide as tailored anti-hindlimb ischemic nanomedicine

Therapeutic angiogenesis is one of the most promising solutions to the clinical dilemma of critical limb ischemia (CLI). Promoting the morphogenesis of endothelial cells (ECs) and normalizing the microenvironment are the right pathways for angiogenesis, but existing strategies are limited by inefficiency, complexity and high cost. Oriented by clinical needs and engineering applications, an innovative nano-system was developed from bridging facile/cost-effective metal-organic frameworks (MOFs) for delivering bioactive zinc ion and versatile hydrogen sulfide (H2S). These MOFs were surface-modified with a multi-functional layer and evaluated as a potential tailored anti-hindlimb ischemic nanomedicine. As a holistic strategy, the combination of zinc ion and H2S generated from zinc MOFs (Zn-MOFs) and diallyl trisulfide (DATS) can integrally modulate EC behavior and microenvironment for more effective functional rehabilitation of ischemic limb. Specifically, zinc ion and H2S together amplified the pro-angiogenic effect on ECs, while H2S also alleviated post-ischemic oxidative stress and inflammation by inducing pro-healing and anti-inflammatory M2-type macrophages. Furthermore, surface-engineering of MOFs reduced the toxicity of nanomedicine and improved its utilization in intramuscular injection. Overall, the nano-system not only enables safe and effective H2S administration, but also presents a new potential option for CLI clinical therapy as an efficacious/facile/cost-effective nanomedicine.