Zinc Imidazolate Research Articles

Fabrication of Gold and Silver Nanoparticles Supported on Zinc Imidazolate Metal-Organic Frameworks as Active Catalysts for Hydrogen Release from Ammonia Borane.

Well-dispersed Au and Ag nanoparticles (NPs) have been immobilized on a zinc imidazolate metal-organic framework, Zn(mim), using the "one-pot" method and tested as catalysts in ammonia borane hydrolysis. The AuNPs@Zn(mim) and AgNPs@Zn(mim) materials were characterized by FTIR, XRD, ICP-OES, TGA, BET, SEM, and TEM. The AgNPs@Zn(mim) catalyst showed a high yield (98.5%) and high hydrogen generation rate (3352.71 mL min-1 gAg -1) in NH3BH3 dehydrogenation. The determined activation energies (19.6 kJ mol-1 for AuNPs@Zn(mim) and 38.13 kJ mol-1 for AgNPs@Zn(mim)) are lower than those for most reported catalysts containing Au/Ag-MOF used in the hydrolysis of NH3BH3. Moreover, the catalysts tested here revealed good stability and reusability, preserving 71.42% (AuNPs@Zn(mim)) and 88.23% (AgNPs@Zn(mim)) of their initial catalytic activities after five consecutive cycles. In the case of AgNPs@Zn(mim), the combination of the simple and green synthesis method, low active metal content, relatively low cost, and moderate dehydrogenation conditions makes the material an excellent candidate to produce hydrogen from ammonia borane.

Peptide-Guided Metal-Organic Frameworks Spatial Assembly Sustain Long-Lived Charge-Separated State to Improve Photocatalytic Performance.

The controlled fabrication of spatial architectures using metal-organic framework (MOF)-based particles offers opportunities for enhancing photocatalytic performances. The understanding of the contribution of assembly to a precise photocatalytic mechanism, particularly from the perspective of charge separation and extraction dynamics, still poses challenges. The present report presents a facile approach for the spatial assembly of zinc imidazolate MOF (ZIF-8), guided by β-turn peptides (SAZH). We investigated the dynamics of photoinduced carriers using transient absorption spectroscopy. The presence of a long-lived internal charge-separated state in SAZH confirms its role as an intersystem crossing state. The formation of an assembly interface facilitates efficient electron transfer from SAZH to O2, resulting in approximately 2.6 and 2 times higher concentrations of superoxide (·O2-) and hydrogen peroxide (H2O2), respectively, compared to those achieved with ZIF-8. The medical dressing fabricated from SAZH demonstrated exceptional biocompatibility and exhibited an outstanding performance in promoting wound restoration. It rapidly achieved hemostasis during the bleeding phase, followed by a nearly 100% photocatalytic killing efficiency against the infected site during the subsequent inflammatory phase. Our findings reveal a pivotal dynamic mechanism underlying the photocatalytic activity of control-assembled ZIF-8, providing valuable guidelines for the design of highly efficient MOF photocatalysts.

N/O-bridge stimulated robust binding energy and fast charge transfer between carbon nanofiber and NiCo LDH for advanced supercapacitors

Layered double hydroxide (LDH)-carbon composites effectively mitigate the inherent issues of agglomeration and poor conductivity in LDH. However, the weak binding energy and insufficient charge transfer capability between LDH and carbon substrate significantly compromise the active substance loading, cyclic stability and practical capacity of the composites. Herein, N/O co-doping porous carbon nanofibers (NOPCNFs) are first prepared by blending diminutive zinc imidazolate framework-8 nanoparticles with polyacrylonitrile for electrospinning, and then densely packed NiCo LDH nanosheets are homogeneously anchored on NOPCNFs to form NiCo LDH@NOPCNFs heterostructure via a hydrothermal method. The experimental findings and density functional theory calculation results indicate that N/O atoms exhibit robust binding forces with metal atoms through enhanced electrostatic adsorption and p-d covalent hybridization, which facilitates the nucleation and development of NiCo LDH on carbon nanofibers. Meanwhile, these heteroatoms also serve as the bridge for electron transfer from NiCo LDH to NOPCNF, leading to a strong interfacial electric field, thus accelerating charge transfer behaviors. Benefitting from the synergistic interaction between NiCo LDH and NOPCNF, the obtained NiCo LDH@NOPCNFs demonstrate an elevated mass loading of active substance (55 wt%), an impressive specific capacitance of 1340 F/g at 1 A/g (based on the mass of NiCo LDH, 2463 F/g), and good cyclic durability for 5000 cycles. Moreover, an all-solid-state asymmetric supercapacitor using NOPCNFs and NiCo LDH@NOPCNFs shows promising practical application prospects. This work gives insights into the important influence of heteroatom doping in carbon, and provides a feasible approach for the efficient integration of electroactive and carbon material.

Quest for the porosity-regulated high dielectric and conductive performance of MOF by introducing nanoparticles: Performance evaluation at elevated temperatures

Metal-organic frameworks (MOFs) are among the novel materials that have drawn a lot of attention from the scientific and technological communities. There have been numerous reports of 3D MOFs in the scientific community, but due to distinct structural and electrical properties, scientists are particularly interested in zinc imidazole framework 8 (ZIF-8). Due to its characteristic low dielectric values, ZIF-8 is an excellent choice for low-dielectric applications. However, the incorporation of nanoparticles can increase the dielectric constant of ZIF-8. In this study, ZnO semiconducting nanoparticles are used as a filler of ZIF-8 due to their exceptionally high electron mobility, exciton binding energy, and wide band gap. We hypothesized that the incorporation of semiconducting nanoparticles (ZnO) inside ZIF-8 influences the porosity, pore size distributions, pore morphology, and interconnectivity of ZIF-8 which influences the polarization of pristine ZIF-8 and helps to increase the dielectric properties. ZnO has inherent ionic polarization which not only enhances the dielectric constant but also simultaneously decreases the dielectric loss which is essential for any dielectric materials. The dielectric constant was enhanced by 1.5 times after 5 wt% ZnO doping in ZIF-8 at room temperature and the enhancement was nearly five times at 150 °C. Simultaneously the dielectric loss decreases after ZnO doping compared to pristine ZIF-8. The tailoring of porosity, the number of pores, the presence of defects and oxygen vacancies are responsible for the modulated dielectric properties. The conductivity of ZIF-8 can also be tuned by the nanoparticles incorporation which indicates the larger production of drift electrons inside MOF in the presence of nanoparticles. The detailed morphological characteristics confirm the interaction between ZnO and ZIF-8. The result is a thorough understanding of the intrinsic and extrinsic electrical properties of ZIF-8 composites for future generations of technology. This work aimed to exploit possibilities of MOF towards high dielectric constant and low loss material by simple nanoparticle incorporation.

Zinc Imidazole Framework‐8 Nanoparticles Disperse MRSA Biofilm by Inhibiting Arginine Biosynthesis and Down‐Regulating Adhesion‐Related Proteins

AbstractNanomaterials, including ZIF‐8 nanoparticles (NPs), are shown to be effective antimicrobial agents against Methicillin‐resistant Staphylococcus aureus(MRSA). However, the antibiofilm properties and mechanisms of ZIF‐8 NPs remain uncertain. In this study, ZIF‐8 NPs are prepared using the room temperature solution reaction method and characterized. Biofilm formation inhibition test and biofilm eradication test are performed and the results show that ZIF‐8 NPs can inhibit the formation of MRSA biofilm as well as disperse established MRSA biofilm. Proteomics and real‐time fluorescence quantitative polymerase chain reaction (PCR) are conducted to prove that ZIF‐8 NPs reduce the expression of adhesion‐related proteins, namely the fibronectin‐binding proteins A and B (fnbA/fnbB), fibrinogen binding protein caking factors A and B (clfA/clfB), elastin binding protein (ebps), and fibrin binding protein (eno). ZIF‐8 NPs also inhibit the arginine biosynthesis pathway by affecting the activities of argininosuccinate lyase, ornithine carbamyl transferase, Glutamate dehydrogenase, carbamate kinase, and arginine deiminase. A conclusion can be drawn from the above results that ZIF‐8 NPs can inhibit bacterial adhesion and kill bacteria directly, ultimately destroying MRSA biofilm. This study provides a molecular basis for the treatment of MRSA biofilm with ZIF‐8 NPs.

Construction of PDA-PEI/ZIF-L@PE tight ultra-filtration (TUF) membranes on porous polyethylene (PE) substrates for efficient dye/salt separation

Tight ultra-filtration (TUF) membranes were constructed by in situ growing zinc imidazole frameworks micro-crystalline leaves (ZIF-L) in polyethylene imine (PEI) and polydopamine (PDA) deposit layers on porous polyethylene (PE) substrates. The effects of preparation conditions on the surface physical and chemical structures as well as on the dye/salt separation performance of the formed TUF membranes were systematically investigated. By inserting selective water permeation channels and increasing contacting surface areas, in situ-grown ZIF-L arrays tightly cross-linked in the coating matrix greatly increased water permeation without trading off dye/salt retention selectivity. The morphology of the included ZIF-L particles could be varied by adjusting the ligand/Zn molar ratio (α) in the preparation processes. Optimized PDA-PEI/ZIF-L@PE TUF membranes containing ZIF-L of cross-cross block morphology showed very high pure water permeability of 180 ± 20 L·m−2·h−1·bar−1 (LMHB) and retention selectivity (SCR/Na2SO4 and SMB/Na2SO4) of 267 and 43, respectively, as well as excellent stability and anti-fouling properties.

Cobalt and zinc imidazolate encapsulated in reduced graphene oxide and the derived nitrogen-enriched carbon frameworks (CoNC@rGO) for electrochemically sensing acetaminophen (APAP)

Electrochemical detection of the analgesic acetaminophen (APAP) was carried out using a composite of cobalt and zinc imidazolate frameworks and graphene oxie (Co/ZnZIF@GO). Co/ZnZIF@GO was thermally reduced to create cobalt/nitrogen-enriched carbon and reduced graphene oxide (CoNC@rGO), which greatly facilitated the current response for APAP sensing. The mesoporosity of NC cubes embedded in rGO sheets and the dispersity of Co nanoparticles were manipulated by the carbonization temperature. Electroanalysis and Raman spectra revealed that the reversible conversion of phenolic hydroxyl to ketone in the doubly chelated APAP on surface Co sites accounted for the faradaic current of APAP oxidation. CoNC@rGO(800), synthesized at 800 °C under a N2 atmosphere, with an optimal metal ratio of Co0.5Zn0.5 and 50 % GO loading maximized electrode sensitivity. This resulted in a high sensitivity (0.598 μA μM−1) and a low detection limit (0.067 μM) in the range of 0.5–50 μM. Through the differential pulse voltammetry technique (DPV), the synthesized sensor exhibited excellent reproducibility, selectivity, and recovery for detecting APAP in various real-world water samples.

Fe-N-C Oxygen Reduction Catalysts Via Chemical Vapor Deposition in Fluidized Bed Reactor

Metal nitrogen carbon catalysts (MNC) are an attractive substitute for platinum-based catalysts in the oxygen reduction reaction (ORR) in PEM fuel cells. However, state-of-the-art MNC catalysts still suffer from low activity and instability. Li et al. [1] demonstrated the use of zinc imidazolate frameworks (ZIF-8) in chemical vapor deposition (CVD) to form active sites without unwanted particle formation or additional treatment steps. In this method, gaseous iron chloride exchanges the zinc in the precatalyst to form active sites.In this work, we introduce a vertical fluidized bed reactor (FBR) for high-scale synthesis of FeNC via CVD, allowing for uniform dispersion of the precatalyst and better zinc-iron exchange. Furthermore, we investigated the influence of differently sized ZIF-8 on the CVD and the formation of the FeNC catalyst.The final catalysts were characterized for their electrochemical activity in a rotating ring disc setup, their site density via CO-chemisorption, and their respective turnover frequency. The physicochemical characterization includes the analysis of surface area and pore structure via nitrogen physisorption, SEM, and TEM, as well as surface structure and compositional analysis via elemental analysis, ICP-OES, and XPS.The exchange of Zn was in the range of 90%, resulting in an iron content of 3.8 wt% with only the formation of desired Fe-Nx active sites. STEM-EDX imaging shows an even distribution of iron and nitrogen in the catalyst, with mean particle sizes of 110 nm. In rotating disc electrode experiments with 0.5 M sulfuric acid, mass activities of 0.23 A/g at 0.9 V vs RHE were achieved.Commercially nano-scaled ZIF-8 with mean particle sizes of 500 nm, synthesized particles with mean sizes of 110 nm were tested, compared to the commercial ZIF-8 Basolite Z1200 with mean particle sizes of 4.9 µm. We could show improved activity in RRDE of the nano-scaled ZIF-8 materials compared to the macro-scaled Basolite.Applying this highly scalable synthesis method for MNC catalysts could be a viable way to achieve high-performance catalysts for ORR.[1] Li Jiao, Jingkun Li, Lynne Larochelle Richard, Qiang Sun, Thomas Stracensky, et al.. Chemical vapour deposition of Fe–N–C oxygen reduction catalysts with full utilization of dense Fe–N4 sites. Nature Materials, 2021, 20, pp.1385-1391.

Imidazolate framework material for crude oil removal in aqueus media: Mechanism insight

Considerable amount of produced water discharged by the oil industry contributes to an environmental imbalance due to the presence of several components potentially harmful to the ecosystem. We investigated the factors influencing the adsorption capacity of Zinc Imidazolate Framework-8 (ZIF-8) in finite bath systems for crude oil removal from petroleum extraction in synthetic produced water. ZIF-8, experimentally obtained by solvothermal method, was characterized by XRD, FTIR, TGA, BET and its point of zero charge (pHpcz) was determined. Synthesized material showed high crystallinity, with surface area equal to 1558 m2 g−1 and thermal stability equivalent to 400 °C. Adsorption tests revealed, based on the Sips model, that the process takes place in a heterogeneous system. Additionally, intraparticle diffusion model exhibited multilinearity characteristics during adsorption process. Thermodynamic investigation demonstrated that adsorption process is spontaneous and exothermic, indicating a physisorption phenomenon. These properties enable the use of ZIF-8 in oil adsorption, which presented an adsorption capacity equal to 452.9 mg g−1. Adsorption mechanism was based on hydrophobic interactions, through apolar groups present on ZIF-8 structure and oil hydrocarbons, and electrostatic interactions, through the difference in charges between positive surface of adsorbent and negatively charged oil droplets.

Unit-cell-thick zeolitic imidazolate framework films for membrane application

Zeolitic imidazolate frameworks (ZIFs) are a subset of metal–organic frameworks with more than 200 characterized crystalline and amorphous networks made of divalent transition metal centres (for example, Zn2+ and Co2+) linked by imidazolate linkers. ZIF thin films have been intensively pursued, motivated by the desire to prepare membranes for selective gas and liquid separations. To achieve membranes with high throughput, as in ångström-scale biological channels with nanometre-scale path lengths, ZIF films with the minimum possible thickness—down to just one unit cell—are highly desired. However, the state-of-the-art methods yield membranes where ZIF films have thickness exceeding 50 nm. Here we report a crystallization method from ultradilute precursor mixtures, which exploits registry with the underlying crystalline substrate, yielding (within minutes) crystalline ZIF films with thickness down to that of a single structural building unit (2 nm). The film crystallized on graphene has a rigid aperture made of a six-membered zinc imidazolate coordination ring, enabling high-permselective H2 separation performance. The method reported here will probably accelerate the development of two-dimensional metal–organic framework films for efficient membrane separation.

Synergistic C-TiO2/ZIF-8 type II heterojunction photocatalyst for enhanced photocatalytic degradation of methylene blue.

Zinc imidazolate framework (ZIF-8) and titanium dioxide (TiO2) have been extensively studied as photocatalysts and have shown remarkable potential. In this study, we report the synthesis of a type II heterojunction photocatalyst based on carbon-doped TiO2 (C-TiO2) and ZIF-8 as a potentially improved material for solar light-harvested methylene blue (MB) degradation. Pure ZIF-8 has a wide band gap of 4.9eV, due to which the application of this material to visible light-assisted photocatalytic performance is a challenging task. Therefore, C-TiO2 has been chosen as a composite material with ZIF-8 owing to its narrow band gap compared to TiO2. This enables the free radical-initiated photocatalytic reaction to shift into the visible region instead of the ultraviolet region. To construct the C-TiO2/ZIF-8 heterostructure, the zinc-based ZIF matrix has been built upon the exterior of C-TiO2 nanoparticles. UV-Vis diffuse reflectance spectroscopy (UV-Vis-DRS) corroborated the decrease in the band gap of ZIF-8 after the fabrication of C-TiO2/ZIF-8, while X-ray diffraction (XRD) analysis demonstrated a decrease in average d-spacing and average crystallite size of the synthesized photocatalyst. Raman spectra and X-ray photoelectron spectroscopy (XPS) analysis of the synthesized samples were also performed to further understand their chemical structure and elemental content. Ultraviolet photoelectron spectroscopy (UPS) and high-resolution transmission electron microscopy (HRTEM) analyses were performed to understand the valence band (VB) states and the morphology of C-TiO2/ZIF-8. The comparison between pure ZIF-8 and C-TiO2/ZIF-8 in the photocatalytic degradation of MB under visible light has also been drawn. A possible charge-transfer mechanism for the same has also been proposed. It is concluded that the synergistic effect of C-TiO2 and ZIF-8 in C-TiO2/ZIF-8 produces an effective material for photocatalytic dye degradation.

Dairy industry wastewater treatment by MOF and 2D nanomaterial engineered PVDF membranes based aerobic MBR: Membrane fouling mitigation and stability study

In the present research work, PVDF membranes are embedded using zinc imidazolate framework-8 and molybdenum disulfide. The membrane's impact is investigated using their permeability, separation performance, reusability and stability performance and fouling resistance. Results show that the ZIF-8 and MoS2 based PVDF nanocomposite membranes have superior pure water flux performance, such as 27.71 L/m2 h and 32.53 L/m2 h, respectively. The FRR of the ZIF-8 and MoS2-based PVDF nanocomposite membranes is obtained at 95.65 % and 97.04 %, respectively. The flux recovery ratio and water contact angle studies show that prepared membranes have better antifouling performance than pristine PVDF membranes. The pollutant removal performance for COD, BOD5, TN, NH4-N and TP is obtained as 94.08 %, 95.31 %, 94.5 %, 95.56 % and 94.64 %, respectively, from dairy industry wastewater. Also, the microbial culture growth study report that the ZIF-8 and MoS2 based PVDF membranes reject maximum microbes from the treated water. Therefore, the prepared PVDF nanocomposite membranes show outstanding filtration performance, reusability, and long-term stability performance. Hence, the ZIF-8 and MoS2 nanomaterials significantly improved the PVDF membrane's characteristics and could be a promising nanocomposite membrane for practical application in different wastewater treatments.

Synthesis of CdSe QDs decorated ZIF-8 composite for visible light assisted degradation of methylene blue

Metal organic frameworks have proven to be a crucial facet for the enhancement of environmental research because of their excellent properties, especially, extensive surface area. In the present study, we propose the synthesis route of CdSe quantum dots (CdSe QDs) and zinc imidazole framework-8 (ZIF-8) composite for the effective and potential methylene blue (MB) degradation via photocatalysis in visible range which is kinetically a pseudo first-order reaction. ZIF-8 itself is a photocatalyst but it has large band gap (4.8–5.1 eV) in ultraviolet region. The doping of CdSe QDs into the ZIF-8 matrix is done with the aim of deviating the photocatalytic activity to visible range by lowering of the band gap of ZIF-8 which was validated by UV–vis–DRS. XRD results indicated the decrease in the d-spacing, crystallite size and also provided the information about the positive microstrain for all the components. FTIR and Raman spectra confirmed the composite synthesis and the CdSe longitudinal (LO) and surface optical phonon modes (SO) along with the fundamental modes of ZIF-8, respectively. The elemental state of the constituent was established by XPS analysis. The adsorption isotherm data and the kinetic studies indicate that the CdSe-ZIF-8 composite has a great potential as a catalyst.

An integrated experimental and simulation study on the loading of cytarabine in a biocompatible zinc imidazole metal–organic framework

An integrated experimental and simulation study on the loading of cytarabine in a biocompatible zinc imidazole metal–organic framework

Non-3d metal modulated zinc imidazolate frameworks for CO2 cycloaddition in simulated flue gas under ambient condition

Cycloaddition of CO 2 and epoxide into cyclic carbonate is one of the most efficient ways for CO 2 conversion with 100% atom-utilization. Metal–organic frameworks are a kind of potential heterogeneous catalysts, however, high temperature, high pressure, and high-purity CO 2 are still required for the reaction. Here, we report two new Zn(II) imidazolate frameworks incoporating MoO 4 2– or WO 4 2– units, which can catalyse cycloaddition of CO 2 and epichlorohydrin at room temperature and atomospheric pressure, giving 95% yield after 24 h in pure CO 2 and 98% yield after 48 h in simulated flue gas (15% CO 2 + 85% N 2 ), respectively. For comparison, the analogic Zn(II) imidazolate framework MAF-6 without non-3d metal oxide units showed 71% and 33% yields under the same conditions, respectively. The insightful modulation mechanisms of the MoO 4 2– unit in optimizing the electronic structure of Zn(II) centre, facilitating the rate-determined ring opening process, and minimizing the reaction activation energy, were revealed by X-ray photoelectron spectroscopy, temperature programmed desorption and computational calculations. Two new zinc imidazolate frameworks integrated with non-3d metal MoO 4 2− and WO 4 2− units were prepared, which displayed significantly enhanced catalytic activities toward CO 2 cycloaddition reaction under ambient condition, even with simulated flue gas.

Zinc Imidazolate Metal–Organic Frameworks-8-Encapsulated Enzymes/Nanoenzymes for Biocatalytic and Biomedical Applications

Zinc Imidazolate Metal–Organic Frameworks-8-Encapsulated Enzymes/Nanoenzymes for Biocatalytic and Biomedical Applications

ZIF-8 modified poly (m-phenylene isophthalamide) (PMIA) hybrid membrane for dye wastewater treatment

The separation of dye/salt through the separation membranes is a great significance for the treatment of dye wastewater. In this study, a novel PMIA hybrid membrane was fabricated via nonsolvent induce phase separation (NIPS) method, in which porous zinc imidazolate framework-8 (ZIF-8) was utilized as a filler. The effect of ZIF-8 content on the structure and performance of PMIA/ZIF-8 membrane was investigated. The results showed that the structure and performance of the PMIA/ZIF-8 membrane could be controlled by changing the content of ZIF-8. The proper content of ZIF-8 was 0.45 wt% in this study. To further enhance the water flux of PMIA/ZIF-8 membrane, the concept of creating nanovoids within the ZIF-8 nanoparticle via wet-chemical etching method was explored in this study. The additional pore of ZIF-8 nanoparticles after wet-chemical etched endows PMIA/ZIF-8 membrane with additional pathways for water molecules. Hence, the PMIA/ZIF-8 membrane after wet-chemical etching showed higher separation performance for dye wastewater. The optimized PMIA/ZIF-8 membrane showed a water permeance of 104.7 L·m−2·h−1 and Congo red rejection of 98% at 0.1 MPa. The water permeance was about 1.5 times than that of the pristine PMIA/ZIF-8 membrane while the Congo red rejection was well maintained. Moreover, the PMIA/ZIF-8 membrane showed good thermal stability during the filtration process. These results indicated that PMIA/ZIF-8 membrane has potential application in dye wastewater treatment.

Engineering the ZIF-8 Pore for Electrochemical Sensor Applications-A Mini Review.

Zinc imidazole framework-8, abbreviated as ZIF-8, is a member of the metal organic framework (MOF) family. The chemical architecture of ZIF-8 consists of zinc metal duly coordinated with an organic ligand/fragment, resulting in a cagelike three-dimensional network with unique porosity. Because of such a unique architecture and physicochemical property, ZIF-8 has recently been explored in various applications such as gas storage, catalysis, electrochemical sensing, drug delivery, etc. Electrochemical sensors are currently a hot topic in scientific advances, where small, portable, Internet of Things (IoT)-enabled devices powered by electrochemical output show a newer path toward chemo and biosensor applications. The unique electrochemical property of ZIF-8 is hence explored widely for possible electrochemical sensor applications. The application and synthesis of the bare ZIF-8 have been widely reported for more than a decade. However, new scientific advancements depict tailoring the bare ZIF-8 structure to achieve smart hybrid ZIF-8 materials that show more advanced properties compared to bare ZIF-8. The framework is formed by joining inorganic (metal-containing) units with organic linkers by reticular synthesis, which results in the formation of a cross-linked crystalline network with permanent porosity. This unique porosity of ZIF-8 has recently been utilized for the encapsulation of suitable guest species to enhance the native physicochemical activity of ZIF-8. These engineered ZIF-8 materials show excellent results, especially for electrochemical sensing application. This review is intended to describe the research, including the one done by our group, where the ZIF-8 pore size is used for encapsulating nanoparticles, enzymes, and organic compounds to avail suitable sensor applications.

Self-Adaptive Dirhodium Complexes in a Metal-Organic Framework for Synthesis of N-H Aziridines.

Conformational dynamics of active sites in enzymes enable great control over the catalytic process. Herein, we constructed a metal-organic framework with conformationally dynamic active sites (Rh2-ZIF-8). The active sites in Rh2-ZIF-8 were composed of the imidazolate-bridged bimetallic center with a catalytic dirhodium moiety and structural zinc site. Even though the coordination sphere of the dirhodium species was saturated with two circularly arranged esp groups and two axial 2-MeIm ligands, it could still effectively catalyze the direct synthesis of N-H aziridines from olefins with high activity. We found that such a self-adaptive catalytic process was based on the dynamic breakage and reformation of the rhodium-zinc imidazolate bridges. Interestingly, the in situ generated dirhodium site with a unique Rh2(esp)2(2-MeIm)1 configuration was able to exhibit obviously enhanced selectivity compared to homogeneous catalyst Rh2(esp)2. Furthermore, the surrounding zinc imidazolate groups could effectively protect the dirhodium moieties from harsh environments, and this ultimately endowed it with high stability.

Toxicological Impact and in Vivo Tracing of Rhodamine Functionalised ZIF-8 Nanoparticles.

Metal Organic Frameworks (MOFs) are extensively used for a wide range of applications due to their exceptionally high surface area. MOF particles are conventionally in micron size, but the nanosized MOFs show good transportation/mobility due to their small size, and when combined with the high surface area of MOFs, it makes MOF nanoparticles an ideal candidate to study for environmental remediation. Therefore, it is important to study the ecotoxicological impact of these MOFs. In this study, we developed rhodamine labelled nanoparticles of zinc imidazolate metal organic framework (ZIF-8 MOFs) as a means of in vivo tracing the MOF translocation in C. elegans. Rhodamine B isothiocyanate functionalized ZIF-8 MOFs nanoparticles (RBITC@ZIF-8 MOF nanoparticles; size 44 ± 7 nm) were fed to the worms naturally within a concentration range of 0.16–16.4 μg mg−1. Fluorescence was detected in the pharyngeal and gut lumen regions of the worms after 4 h of treatment, for exposure concentrations >0.163 μg mg−1. A higher intensity of fluorescence was observed at the end of 24 h for all exposure concentrations. Worms treated with RBITC@ZIF-8 MOF concentrations of ≥1.63 μg mg−1 for 24 h showed a bright stable fluorescence signal at the tail region. The uptake of RBITC@ZIF-8 MOF for an exposure concentration of 0.163, 1.63, and 8.2 μg mg−1 was found to be 52.1, 11.4 and 28.6%, respectively. Through this study, we showed that RBITC@ZIF-8 MOFs can be exposed to C. elegans and imaged at low concentrations of ∼0.16 μg mg−1.