Comparison of MIL-101(Fe) and amine-functionalized MIL-101(Fe) as photocatalysts for the removal of imidacloprid in aqueous solution

Highly sensitive determination of trace arsenic(III) onto carbon paste electrode modified with graphitic carbon nitride decorated Fe-MOF

An effective electrochemical sensor was developed to detect and determine of the As(III) by modifying the carbon paste electrode (CPE) with graphitic carbon nitride decorated with iron-based metal-organic frameworks (Fe-MOF/g-C3N5). The differential pulse anodic stripping voltammetry (DPASV) method was used to analyze As(III) ions in a phosphate buffer solution (0.10 M, pH = 5). Fe-MOF/g-C3N5/CPE showed high sensitivity (4.24 μA μg-1 L), satisfactory linear range (0.50 μg L-1-5.00 μg L-1 and 5.00 μg L-1-30.00 μg L-1), and low detection limit (LOD, 0.013 μg L-1). The prepared sensor was showed an excellent repeatability and selectivity, and successfully used for determination of the As(III) ion in ambient waters and apple juice samples.

Highly Efficient Photocatalytic Degradation of Imidacloprid Based on Iron Metal-Organic Frameworks of Mesoporous NH2-MIL-88b/Graphite Carbon Nitride Nanocomposites by Visible Light Driven in Aqueous Media

Pesticides that protect crops from insects and other pests are some of the main causes of water pollution. Imidacloprid (IMC) is the most widely used insecticide in the world and should be removed from the environment. This work aims to prepare mesoporous nanocomposites to increase the photodegradation efficiency of IMC. To improve the surface properties and enhance the photocatalytic activity, mesoporous nanocomposites with different weight ratios of graphite carbon nitride (CN = 125, 250, and 500 mg) were prepared by the solvothermal method. Mesoporous NH2-MIL-88b(Fe)/graphite carbon nitride (CN = 250 mg, NH2-MCN-2) nanocomposites showed the best photocatalytic performance. To save the time and cost of the experiments, central composite design (CCD) and response surface methodology (RSM) were used and the results were obtained as the initial concentration of IMC (20 mg L-1), amount of photocatalyst (0.76 g L-1), pH = 5, and degradation time ∼46 min. The maximum photocatalytic degradation efficiency estimated by the model was obtained at 96.31%, which is very close to the actual value of 95.47%. The mesoporous NH2-MCN-2 nanocomposite showed excellent stability and suitable reusability with a maximum degradation of 84.5% after five cycles. Results obtained from kinetic studies indicated a rate constant value of 0.08 min-1, and isotherm models showed that equilibrium data are more consistent with the Langmuir model in photocatalytic degradation. Electrochemical experiments showed significant improvement in the electron transfer rate and photocatalytic activity of the mesoporous NH2-MCN-2 nanocomposite. Different trapping agents were used to investigate the effective active species in IMC photodegradation, and it was determined that the hole (h+) and OH radical (•OH) play the main role. The possible mechanism for IMC photocatalytic degradation was suggested by Mott-Schottky (M-S) electrochemical impedance.

Using Quercetin to Construct Molecularly Imprinting Polymer in the Preparation and Enrichment of Flavonol and Flavonoid Compounds

Flavonol and flavonoid compounds are important natural compounds with various biomedical activities. Therefore, it is of great significance to develop a strategy for the specific extraction of flavonol and flavonoid compounds. Quercetin is a well-studied flavonoid possessing many health benefits. This compound is a versatile antioxidant known to possess protective abilities against body tissue injury induced by pathological situations and various drug toxicities. Although quercetin is widely distributed in many plants, its content generally is not very high. Therefore, the specific extraction of quercetin as well as other flavonol and flavonoid compounds has profound significance. In this work, the quercetin molecularly imprinting polymer (QMIP) was successfully prepared, in which a typical flavonol quercetin was selected as the template molecule. QMIP was synthesized by performing the surface molecular imprinting technology on the surface of NH2-MIL-101(Fe). Our study results showed that QMIP exhibited quick binding kinetic behavior, a high adsorption capacity (57.04[Formula: see text]mg/g), and the specific recognition ability toward quercetin compared with structurally distinct compounds (selective [Formula: see text]). The specific adsorption ability of quercetin by QMIP was further explained using computation simulation that molecules with non-planar 3D conformations hardly entered the molecularly imprinted cavities on QMIP. Finally, QMIP was successfully used for the specific extraction of quercetin and five other flavonol and flavonoid compounds in the crude extracts from Sapium sebiferum. This study proposes a new strategy to synthesize the molecularly imprinted polymer based on a single template for enriching and loading a certain class of active ingredients with similar core structures from variable botanicals.

A sensitive immunosensing platform based on the high cathodic photoelectrochemical activity of Zr-MOF and dual-signal amplification of peroxidase-mimetic Fe-MOF

Cathodic photoelectrochemical (PEC) analysis has received special concerns because of its outstanding anti-interference capability toward reductive substances in samples, so it is highly desirable to develop high-performance photocathodic materials for PEC analysis. Herein, a Zr-based metal-organic framework (Zr-MOF), MOF-525, is explored as a photoactive material in aqueous solution for the first time, which shows a narrow band-gap of 1.82 eV, excellent visible-light absorption, and high cathodic PEC activity. A sandwiched-type PEC immunosensor for detecting prostate-specific antigen (PSA) is fabricated by using MIL-101-NH2(Fe) label and MOF-525 photoactive material. MIL-101-NH2(Fe) as a typical Fe-MOF can serve as a peroxidase mimic to catalyze the production of precipitates on the photoelectrode. Both the produced precipitates and the MIL-101-NH2(Fe) labels can quench the photocathodic current, enabling "signal-off" immunosensing of PSA. The detection limit is 3 fg mL-1, and the linear range is between 10 fg mL-1 and 100 ng mL-1 for detecting PSA. The present study not only develops a high-performance Zr-MOF photoactive material for cathodic PEC analysis but also constructs a sensitive PEC immunosensing platform based on the dual-signal amplification of peroxidase-mimetic Fe-MOF.

Effective removal of acetamiprid and eosin Y by adsorption on pristine and modified MIL-101(Fe)

In this work, the efficacy of two metal-organic frameworks (MIL-101(Fe) and NH2-MIL-101(Fe)) in eliminating acetamiprid (ATP) insecticide and eosin Y (EY) dye from aqueous solution is tested. An analysis was conducted on the developed nanocomposite's optical, morphological, and structural characteristics. The adsorption isotherm, kinetics, thermodynamics, reusability, and mechanisms for ATP and EY dye removal were assessed. NH2-MIL-101(Fe) adsorbed 76% and 90% of ATP pesticide and EY dye, respectively after 10 to 15 min in optimum conditions. For both adsorbents, with regard to explaining the isotherm data, the Langmuir model offered the most accurate description. Moreover, the adsorption of ATP and EY dye is described by the pseudo-second-order kinetic model. The maximum adsorption capacities of ATP and EY dye on MIL-101(Fe) were 57.6 and 48.9 mg/g compared to 70.5 and 97.8 mg/g using NH2-MIL-101(Fe). The greatest amount of ATP and EY dye clearance was obtained at a neutral medium for both adsorbents. The results of this investigation demonstrate the effectiveness of MIL-101(Fe) and NH2-MIL-101(Fe) as effective substances in the adsorption process for removing pesticides and dyes from aqueous solution.

Controlled Synthesis of Preferential Facet-Exposed Fe-MOFs for Ultrasensitive Detection of Peroxides

Exposing different facets on metal-organic frameworks (MOFs) is highly desirable to enhance the performance for various applications, however, exploiting a concise and effective approach to achieve facet-controlled synthesis of MOFs remains challenging. Here, by modulating the ratio of metal precursors to ligands, the facet-engineered iron-based MOFs (Fe-MOFs) exhibits enhanced catalytic activity for Fenton reaction are explored, and the mechanism of facet-dependent performance is revealed in detail. Fully exposed (101) and (100) facets on spindle-shaped Fe-MOFs enable rapid oxidation of colorless o-phenylenediamine (OPD) to colored products, thereby establishing a dual-mode platform for the detection of hydrogen peroxide (H2O2) and triacetone triperoxide (TATP). Thus, a detection limit as low as 2.06 nm is achieved, and robust selectivity against a wide range of common substances (>16 types) is obtained, which is further improved by incorporating a deep learning architecture with an SE-VGG16 network model, enabling precise differentiation of oxidizing agents from captured images. The present strategy is expected will shine light on both the rational synthesis of nanomaterials with modulated morphologies and the exploitation of high-performance trace chemical sensors.

Enantiomeric analysis of chiral phenyl aromatic compounds by coated capillary electrochromatography based on a MOF-on-MOF stationary phase

Chiral phenyl aromatic compounds (CPACs) are widely used in drug development, food/cosmetic production, and other organic synthesis processes, and their different enantiomers have distinct physiological activities and application differences. A double-layer metal-organic framework composite (MOF-on-MOF) was obtained by in situ synthesis of chiral metal-organic framework (CMOM-3S) on the surface of an iron-based metal-organic framework (NH2-MIL-101(Fe)). According to our investigation, MOF-on-MOF composite was for the first time applied to the stationary phase of capillary electrochromatography (CEC), and enantioseparations of eight CPACs were accomplished. Compared with single CMOM-3S, the enantioseparation performance of the coated capillary columns based on NH2-MIL-101(Fe)@CMOM-3S was improved by 34.07 ~ 720.0%. The R-/S-mandelic acid in actual sample (apricot leaves) was detected by the newly CEC system to be 0.0118 mg mL-1 and 0.0523 mg mL-1, respectively. The spike recoveries were 96.60 ~ 104.7%, indicating its good stability and accuracy. In addition, the selective adsorption capacity of MOF-on-MOF composites was verified by adsorption experiments.

Target Separation and Potential Anticancer Activity of Withanolide-Based Glucose Transporter Protein 1 Inhibitors from Physalis angulata var. villosa

The glucose transporter 1 (GLUT1) protein is involved in the basal-level absorption of glucose in tumor cells. Inhibiting GLUT1 decreases tumor cell proliferation and induces tumor cell damage. Natural GLUT1 inhibitors have been studied only to a small extent, and the structures of known natural GLUT1 inhibitors are limited to a few classes of natural products. Therefore, discovering and researching other natural GLUT1 inhibitors with novel scaffolds are essential. Physalis angulata L. var. villosa is a plant known as Mao-Ku-Zhi (MKZ). Withanolides are the main phytochemical components of MKZ. MKZ extracts and the components of MKZ exhibited antitumor activity in recent pharmacological studies. However, the antitumor-active components of MKZ and their molecular mechanisms remain unknown. A cell membrane-biomimetic nanoplatform (CM@Fe3O4/MIL-101) was used for target separation of potential GLUT1 inhibitors from MKZ. A new withanolide, physagulide Y (2), together with six known withanolides (1, 3-7), was identified as a potential GLUT1 inhibitor. Physagulide Y was the most potent GLUT1 inhibitor, and its antitumor activity and possible mechanism of action were explored in MCF-7 human cancer cells. These findings advance the development of technologies for the targeted separation of natural products and identify a new molecular framework for the investigation of natural GLUT1 inhibitors.

Ultrarapid and Sustainable Synthesis of Trimetallic-Based MOF (CrNiFe-MOF) from Stainless Steel and Disodium Terephthalate-Derived PET Wastes

Designing easy and sustainable strategies for the synthesis of metal-organic frameworks (MOFs) from organic and inorganic wastes with the efficient removal of phosphate from water remains a challenge. The majority of the reported works have utilized costly precursors and nonsoluble ligands for the synthesis of MOFs. Herein, we have developed a low-cost, simple, and sustainable alternative approach using the coprecipitation method in water at room temperature for the synthesis of a new adsorbent-based trimetallic MOF. Poly(ethylene terephthalate) and stainless steel wastes were used as sources of water-soluble disodium terephthalate ligand and three metallic species (chromium, nickel, and iron salts) for the fabrication of trimetallic MOF (CrNiFe-MOF), respectively. The newly developed MOF demonstrates a superior space-time yield of 5760 g m-3 day-1, reaching a level allowing the industrialization production of this sustainable MOF. The scanning electron microscopy and adsorption studies revealed that the developed trimetallic MOF consists of aggregated nanoparticles and the presence of defective as well as mesoporous structures. This MOF showed an enhanced adsorption capacity of phosphate from real eutrophic water samples and higher stability in a range of pHs. The density functional theory calculations evidenced that the phosphate ions preferentially adsorb over H2O toward the metal oxo-trimers, with the adsorption energies increasing from H3PO4 to PO43- species in line with an improvement of the adsorption performance of CrNiFe-MOF when the pH increases, i.e., when HPO42- and PO43- become more predominant. These calculations also supported that the incorporation of Cr metal sites in the oxo-trimer is expected to boost the phosphate affinity of the MOF. Finally, our work provides an easy and eco-friendly approach for MOF designing to enhance phosphate removal from water.

Photoinduced Dynamic Ligation in Metal-Organic Frameworks

Metal organic frameworks (MOFs), a class of porous crystalline materials consisting of metal-based nodes and organic linkers, have emerged as a promising platform for photocatalysis due to their ultrahigh functional surface area, customizable topologies, and tunable energetics. While interesting photochemistry has been reported, the related photoinduced structural dynamics of MOFs remains unclear. The consensus is that the coordination bonds between MOF nodes and linkers are considered static during photoexcitation, while the open-metal sites on the nodes are taken as the key active sites for catalysis. In this work, through a complementary time-resolved visible and infrared (IR) spectroscopic investigation, along with computational studies, we report for the first time light-induced structural bond dissociation (COO-M) and reformation in an iron-oxo framework, MIL-101(Fe). The probed excited state displayed ligand-to-metal charge transfer (LMCT) characteristics and exhibited a ca. 30 μs lifetime. The incredibly long excited-state lifetime led us to probe potential structural rearrangements that facilitated charge separation in MIL-101(Fe). By probing the vibrational fingerprints of the carboxylate linker upon LMCT photoexcitation, we observed the reversible transition of the carboxylate-Fe bond from a bidentate bridging mode to a monodentate mode, indicating the partial dissociation of the carboxylate ligand. Importantly, the bidentate configuration is recovered on the same time scale of the excited state lifetimes as probed via visible transient absorption spectroscopy. The elucidated photoinduced configurational dynamics provides a foundation for an in-depth understanding of MOF-based photocatalytic mechanisms.

Lewis acidic Fe3+-driven catalytic active Ni3+ formation in Fe-free metal-organic framework for enhanced electrochemical glucose sensing

Manipulating metal valence states and porosity in the metal-organic framework (MOF) by alloying has been a unique tool for creating high-valent metal sites and pore environments in a structure that are inaccessible by other methods, favorable for accelerating the catalytic activity towards sensing applications. Herein, we report Fe3+-driven formation of catalytic active Ni3+ species in the amine-crafted benzene-dicarboxylate (BDC-NH2)-based MOF as a high-performance electrocatalyst for glucose sensing. This work took the benefit of different bonding stability between BDC-NH2 ligand, and Fe3+ and Ni2+ metal precursor ions in the heterometallic NixFe(1-x)-BDC-NH2 MOF. The FeCl3 that interacts weakly with ligand, oxidizes the Ni2+ precursor to Ni3+-based MOF owing to its Lewis acidic behavior and was subsequently removed from the structure supported by Ni atoms, during solvothermal synthesis. This enables to create mesopores within a highly stable Ni-MOF structure with optimal feed composition of Ni0.7Fe0.3-BDC-NH2. The Ni3+-based Ni0.7Fe0.3-BDC-NH2 demonstrates superior catalytic properties towards glucose sensing with a high sensitivity of 13,435 µA mM-1 cm-2 compared to the parent Ni2+-based Ni-BDC-NH2 (10897 μA mM-1cm-2), along with low detection limit (0.9 μM), short response time (≤5 s), excellent selectivity, and higher stability. This presented approach for fabricating high-valent nickel species, with a controlled quantity of Fe3+ integrated into the structure allowing pore engineering of MOFs, opens new avenues for designing high-performing MOF catalysts with porous framework for sensing applications.

Insight into the Structure of MOF-Containing Hybrid Polymeric Microspheres

Polymer science exploited metal organic frameworks (MOFs) for various purposes, which is due to the fact that these materials are ideal platforms for identifying design features for advanced functional materials. The mechanism of polymerization using MOFs, is still largely unexplored and the detailed characterization of both materials in essential to understand the important interactions between the components. In this work modern advanced research methods were used to investigate the properties of MOF-containing hybrid polymeric microspheres. Hydrothermal conversion of CFA-derived iron particles was used to obtain MOF nanostructures, which were then introduced to the structure of hybrid polymer microspheres based on ethylene glycol dimethylacrylate (EGDMA) and triethoxyvinylsilane (TEVS). Chemical structures were confirmed by ATR-FTIR method. To provide information about the elemental composition of the tested materials and for the determination of chemical bonds present in the tested samples XPS method was applied. Morphology was studied using SEM microscopy, whereas porosity was investigated using ASAP technique. Swellability coefficients were determined using typical organic solvents and distilled water. Moreover, the ecological aspect concerning the use of fly ashes deserves to be emphasized.

Application of a novel composite of Fe3O4@SiO2/PAEDTC surrounded by MIL-101(Fe) for photocatalytic degradation of penicillin G under visible light

The novel photocatalyst of Fe3O4@SiO2/PAEDTC@MIL-101(Fe) was prepared based on the sol-gel method, and its structure and morphology were determined by SEM mapping, TEM, XRD, FTIR, and N2 adsorption-desorption analyses. The photocatalytic activity of nanocomposite was evaluated in comparison with other particles as well as adsorption and photolysis processes. The effect of operating parameters showed that the complete degradation of penicillin G (PNG) can be provided at a photocatalyst dosage of 0.6 g/L, radiation intensity of 36 W, pH of 5, and time of 60 min. In the optimum condition, 84% TOC removal was attained and the BOD5/COD rate for the treated effluent was above 0.4, which was representative of the high biodegradability of the treated effluent compared to the raw sample. The findings of energy consumption showed that PNG can be easily and effectively treated by the photocatalytic process based on magnetic MIL-101(Fe) with electrical energy per order between 10 and 20.87 kWh/m3. Due to the excellent interaction between the MIL-101(Fe) and Fe3O4@SiO2/PAEDTC, the photocatalyst stability test showed a recyclability of the particles for 5 consecutive reaction cycles with a minimum reduction of 7%. Solution treated with photocatalyst under UV and visible light sources explained that the toxicity of the effluent after treatment is significantly reduced with the growth of Escherichia coli. Scavenging experiments showed that •OH radical and hole (h+) are the main agents in degrading PNG to CO2, H2O, and biodegradable and low-toxicity products. Finally, the findings of the diagnostic analysis and comparative experiments proved that with the interaction of Fe3O4@SiO2, NH2, and MIL-101(Fe), a lower band gap can be prepared for more absorption of photons and pollutant and also more and faster production of active radicals.

Fabrication of molecularly-imprinted gold nanoparticle-embedded Fe-MOFs for highly selective SERS detection of 17β-estradiol in milk

17β-Estradiol (17β-E2) could accumulate in humans through milk, thus causing diseases by interfering with the function of the endocrine system. However, its detection at a trace level in milk is still a challenge because of matrix interferences. In this work, a core-shell structured polydopamine molecular-imprinted gold nanoparticles (AuNP@MIP-PDA) were embedded into Fe metal-organic framework materials to form a well-defined hexagonal microspindle structure of AuNP@MIP-PDA@MIL-101(Fe). AuNP@MIP-PDA were successfully encapsulated within the MIL-101 crystals through the hydrophobic interaction between organic ligands and the aromatic groups of PDA, the chelating power of catechol groups, as well as the introduction of acetic acid. Combined with the SERS activity of AuNPs, the specific recognition sites from MIPs, and the adsorption and enrichment capability of MIL-101, the fabricated nanohybrids could be designed as highly selective SERS sensors for the detection. By effectively preventing the macromolecule adsorption and the preconcentration of 17β-E2 near the SERS-active surface, the SERS sensor could be directly applied in the selective detection of 17β-E2 in milk without tedious pretreatment. The method demonstrated an outstanding detection limit of 1.95 × 10^-16 mol L^-1, without the interference mainly originating from the two analogues, estrone and estriol. These promising results foresee the potential application of this novel MIP-based SERS sensor in food and environmental sensing.

Ultrasonic-Assisted Fabrication of MIL-100(Fe) Metal-Organic Frameworks as a Carrier for the Controlled Delivery of the Chloroquine Drug

Metal-organic framework materials (MOFs) are materials with an ordered crystalline structure and high porosity that have been intensively investigated for many applications, such as gas adsorption, catalysis, sensors, drug delivery, and so on. Among them, the MOF-based drug delivery system has received increasing interest from scientists worldwide. This work presented the preparation of the MIL-100(Fe) metal-organic framework from the organic ligand of trimesic acid and iron ions with ultrasonic assistance. Scanning electron microscopy (SEM), Brunauer-Emmett-Teller surface area (BET), X-ray diffraction (XRD), infrared spectroscopy (FTIR), and Raman spectroscopy were employed to characterize the prepared MIL-100(Fe) material. MIL-100(Fe) materials synthesized by the ultrasonic method have uniform particle morphology ranging from 100 to 300 nm with a surface area of 1033 m²/g. The prepared MIL-100(Fe) was employed as a carrier for delivering chloroquine drug with a maximal loading capacity of 220 mg/g. The MIL-100(Fe)@chloroquine system was also characterized in detail. The delivery system's slow drug release was studied, showing that nearly 80% of chloroquine molecules were released after 7.5 h of immersing time in PBS and simulated gastric solutions and completely detached from the MIL-100(Fe)@chloroquine system only after approximately 80 h. This result shows the ability to control chloroquine drug release of the material, reducing the possibility of drug shock.

Visible Light-Driven Metal-Organic Framework-Mediated Activation and Utilization of CO2 for the Thiocarboxylation of Olefins

Visible light-mediated photoredox catalysis has emerged to be a fascinating approach for the activation of CO₂ and its subsequent fixation into valuable chemicals utilizing renewable and inexhaustible solar energy. Although great progress has been made in CO₂ photoreduction, visible light-assisted organic synthesis using CO₂ as a reactive substrate is rarely explored. Herein, we report an efficient, facile, and economically viable photoredox-mediated approach for the synthesis of important β-thioacids via carboxylation of olefins with CO₂ and thiols over a porous functionalized metal-organic framework (MOF), Fe-MIL-101-NH₂, as a photocatalyst under ambient conditions. This multicomponent reaction offers wide substrate scope, mild reaction conditions, easy work-up, cost-effective and reusable photocatalysts, and higher product selectivity. Computational studies suggested that CO₂ interacts with the thiophenol-styrene adduct to facilitate the synthesis of β-thioacids in almost quantitative yields.

Determination and speciation of trace inorganic arsenic species in water samples by using metal organic framework mixed-matrix membrane and EDXRF spectrometry

A facile method to selectively determine trace As(V) species in the existence of As(III) one in water samples was developed, which was based on the batch adsorption process by using a miniaturized MIL-101(Fe) mixed-matrix membrane (MOF-MMM) followed by a direct determination through energy dispersive X-ray fluorescence (EDXRF) spectrometry. The quantitative adsorption of As(V) was achieved at pH (3-6) from 30 mL sample in 120 min of equilibrium time by employing the membrane with a monolayer adsorption capacity of Q_o = 1.953 mg g^-1. The direct determination of As(V) adsorbed on the membrane by EDXRF spectroscopy provided a method, not only easy-to-use and operable without elution stage, but also cost effective due to low gas consumption during the analysis. With a limit of detection of 0.094 μg L^-1, analytical performance of the method, which was evaluated on fortified real water samples with three levels of As(V) (5, 10 and 50 μg L^-1), demonstrated good recoveries in the range of 98(±3)-105(±10)%. Furthermore, the speciation of As(III) and As(V) in the fortified real samples containing other ionic species was also successfully achieved by described approach with characteristics of simple, cheap, viable and reproducible.

Surface-initiated polymerization of PVDF membrane using amine and bismuth tungstate (BWO) modified MIL-100(Fe) nanofillers for pesticide photodegradation

Pirimicarb as a pesticide is used to control the aphids in the agriculture field; however, it affects the groundwater ecosystem by leaching through the soil profile. The post-synthetic amine and BWO modified MIL-100 (Fe) nanofillers were synthesized. The photocatalytic property of amine-functionalized and BWO@MIL-100(Fe) nanofillers was confirmed by the lesser bandgap energy than the unmodified MIL-100 (Fe) nanofiller. Herein, we constructed a nanofillers grafted PVDF membrane via in-situ polymerization technique for the pirimicarb reduction and photodegradation. Furthermore, the nanofiller's grafted membranes were characterized by FESEM, XRD, FTIR, and contact angle analysis. The carboxylic acid peak was observed on the FTIR which demonstrated the PAA grafted on the membrane surface and similar crystalline peaks evident that the nanofillers were grafted on the membrane surface. Furthermore, surface morphology studies have exhibited the dispersion of nanofillers and enhanced microvoids in the cross-section of the membrane. The decrease in the water contact angle of the membrane depicted the improved antifouling properties and surface energy. The nanofiller's grafted membranes have shown higher hydrophilicity correlated well with the enhanced pure water flux in the order M4 > M5 > M2 > M3 > M6 > M7 compared to the neat membrane (M1). In BWO@MIL-100(Fe) membrane has shown a higher permeate flux (25.99 L m^-2.h^-1) than the neat PVDF membrane. The BWO@MIL-100(Fe) grafted PVDF membrane has also shown excellent pirimicarb photodegradation of 81% at pH 5. The proposed MIL-100 (Fe) and bismuth tungsten nanocomposite will pave the way for the different MOF-based photocatalytic materials for membrane-based pesticide degradation.

A novel route to the synthesis of α-Fe2O3@C@SiO2/TiO2 nanocomposite from the metal-organic framework as a photocatalyst for water treatment

In this study, an attempt was made to synthesize metal-organic frameworks (MOFs) based magnetic iron particles as photocatalysts for textile dye wastewater. Improvement strategy was a novel two-step dry method without using conventional methods to eliminate the consumption of chemical reagents. First, the heterogeneous photocatalyst of Fe-MOFs derived magnetic carbon nanocomposite with carboxylic acid surface functional groups (Fe@C-COOH) was achieved. Next, the α-Fe₂O₃@C@SiO₂/TiO₂ was successfully synthesized followed by a sol-gel method to coat the SiO₂ shell and a solvothermal method to coat the surface of the intermediate TiO₂ particles. The as-synthesized nanocomposite materials were characterized and physicochemical analytical equipment. Further, the investigation on magnetic photocatalytic nanocomposite α-Fe₂O₃@C@SiO₂/TiO₂ performance of dye degradation and photocatalytic activity on Reactive yellow 145 (RY145), using as an indicator was conducted. The as-synthesized nanocomposite particles were characterized using X-ray powder diffraction (XRD), thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM), X-ray energy dispersive spectroscopy (EDX), and scanning electron microscopy (SEM) techniques. The structural characterization of the as-synthesized materials proved that these methods generate oxygen-containing functional groups, such as, -OH, -CO, and -COOH, which increases the polarity and hydrophilicity of the photocatalyst. The photocatalytic oxidation of RY145 dye under UVc light was discussed by the apparent first-order reaction rate and the kinetic model of the Langmuir-Hinshelwood followed a better fitting. The optimal performance of the composite is at pH = 2, 15 mg/100 mL of photocatalyst dose, 150 mg/L concentration of the dye RY145 at 25 °C temperature under UVc lamp irradiation for 90 min, and with the apparent reaction rate constant was 0.0165 min^-1. The thermodynamic analysis of activation parameters computed by the Eyring model and based on transition state theory (TST), an endothermic reaction with a positive value for Δ^‡H^o (50.16 kJ mol^-1) and a negative value for Δ^‡S^o (-153 J/mol K) both contribute toward achieving positive values for Δ^‡G^o and a nonspontaneous process. The proposed α-Fe₂O₃@C@SiO₂/TiO₂ demonstrated a high capability of photocatalytic degradation up to 97% after five successive cycles at the optimal condition compared to that of Fe₃O₄@C (18.74%) and Fe@C-COOH (77.9%) without reusability.

Highly Efficient and Simultaneous Removal of Cr(VI) and Imidacloprid through a Ferrocene-Modified MIL-100(Fe) Composite from an Aqueous Solution

A novel nanocomposite [Fc-MIL-100(Fe)] was constructed by combining ferrocene (Fc) with the porous structural metal-organic framework [MIL-100(Fe)]. The proposed composite material could simultaneously and efficiently remove hexavalent chromium [Cr(VI)] and imidacloprid and reduced strongly noxious Cr(VI) to weakly noxious trivalent chromium [Cr(III)]. The removal efficiencies of the composite material for Cr(VI) and imidacloprid could reach 95% after 15 h. The adsorption process was determined by kinetics, isotherms, and thermodynamics. The results demonstrated that the adsorption kinetics of Cr(VI) followed the pseudo-second-order model mainly by chemisorption; meanwhile, the adsorption of imidacloprid by the material conformed to the pseudo-first-order kinetics, which indicated that physical adsorption was the main process. Additionally, the intraparticle diffusion model revealed that the uptake of imidacloprid and Cr(VI) occurred via intraparticle diffusion at the composite material. The adsorption procedure for Cr(VI) was fitted to the Langmuir model (R² = 0.995) via monolayer adsorption, and that for imidacloprid was fitted to the Freundlich model (R² = 0.995) due to multilayer or heterogeneous adsorption. The thermodynamic research confirmed that the adsorption procedure was exothermic and spontaneous. Infrared spectroscopy, X-ray photoelectron spectra, and the pH effect implied that intermolecular hydrogen bonding and electrostatic interaction played a crucial role during the removal process. Fc-MIL-100(Fe) also exhibited long-term stability and satisfactory regeneration and reusability. Therefore, this method may enhance an environmentally friendly and prospective approach for concurrently removing imidacloprid and Cr(VI) from wastewater.

MIL-101 (Fe) @Ag Rapid Synergistic Antimicrobial and Biosafety Evaluation of Nanomaterials

Metal-organic frameworks (MOFs), which have become popular in recent years as excellent carriers of drugs and biomimetic materials, have provided new research ideas for fighting pathogenic bacterial infections. Although various antimicrobial metal ions can be added to MOFs with physical methods, such as impregnation, to inhibit bacterial multiplication, this is inefficient and has many problems, such as an uneven distribution of antimicrobial ions in the MOF and the need for the simultaneous addition of large doses of metal ions. Here, we report on the use of MIL-101(Fe)@Ag with efficient metal-ion release and strong antimicrobial efficiency for co-sterilization. Fe-based MIL-101(Fe) was synthesized, and then Ag+ was uniformly introduced into the MOF by the substitution of Ag+ for Fe3+. Scanning electron microscopy, powder X-ray diffraction (PXRD) Fourier transform infrared spectroscopy, and thermogravimetric analysis were used to investigate the synthesized MIL-101(Fe)@Ag. The characteristic peaks of MIL-101(Fe) and silver ions could be clearly seen in the PXRD pattern. Comparing the diffraction peaks of the simulated PXRD patterns clearly showed that MIL-101(Fe) was successfully constructed and silver ions were successfully loaded into MIL-101(Fe) to synthesize an MOF with a bimetallic structure, that is, the target product MIL-101(Fe)@Ag. The antibacterial mechanism of the MOF material was also investigated. MIL-101(Fe)@Ag exhibited low cytotoxicity, so it has potential applications in the biological field. Overall, MIL-101(Fe)@Ag is an easily fabricated structurally engineered nanocomposite with broad-spectrum bactericidal activity.

Adsorption and removal of organophosphorus pesticides from Chinese cabbages and green onions by using metal organic frameworks based on the mussel-inspired adhesive interface

Based on the mussel-inspired adhesive interface (Fe₃O₄-g-C₃N₄@PDA), a novel bionic metal-organic framework (Fe₃O₄-g-C₃N₄-PDA@MIL-101) was successfully prepared. The composite featured a high specific surface area and a multi-microchannel structure, as well as strong thermochemical stability. The structural property of Fe₃O₄-g-C₃N₄-PDA@MIL-101(Fe) was characterized, and the results indicated that Fe₃O₄, PDA, and MIL-101(Fe) were uniformly coated on the g-C₃N₄ surface. The adsorption and desorption of organophosphorus pesticides with Fe₃O₄-g-C₃N₄-PDA@MIL-101(Fe) were evaluated by batch experiments. This composite showed high adsorption efficiency and selective removal of coralox, phosalone, and chlorpyrifos. Under the optimal conditions, three organophosphorus pesticides were adsorbed from Chinese cabbage and green onion samples with Fe₃O₄-g-C₃N₄-PDA@MIL-101(Fe). The analytical method exhibited high sensitivity (LOD, 0.19-2.34 μg/L; LOQ, 0.65-7.82 μg/L), excellent practicality, and good stability, suggesting that Fe₃O₄-g-C₃N₄-PDA@MIL-101 was an ideal candidate magnetic adsorbent for the removal of organophosphorus pesticides in Chinese cabbage and green onion samples.

Growth of Fe-BDC Metal Organic Frameworks onto functionalized Si (111) surfaces

The realization of metal organic frameworks (MOFs) layers onto solid surfaces is a prerequisite for their integration into devices. This work reports the direct growth of Fe 3+ / benzene di-carboxylate MOFs onto functionalized silicon surfaces, compatible with a wide range of MOF synthesis conditions. The co-nucleation and growth of different crystalline phases are evidenced, whose coverage depends on the surface chemistry and/or the solution composition. Three structural phases - the cubic MIL-101(Fe), a hexagonal phase with a structure close to MOF-235 and a MIL-53(Fe) with a monoclinic symmetry - were identified through characteristic crystal shapes and their structural parameters inferred from X-Ray Diffraction. In addition to the oriented growth of 3D crystallites, the formation of two-dimensional MIL-101 nano-crystallites or thin layers/islands exhibiting extended monocrystalline domains with (111) texture is also demonstrated through high-resolution Atomic Force Microscopy. Post-synthesis treatments reveal a weak adhesion of the hexagonal phase indicating a different surface anchoring.

A novel composite of ionic liquid-containing polymer and metal-organic framework as an efficient catalyst for ultrasonic-assisted Knoevenagel condensation

1-Butyl-3-vinylimidazolium chloride was synthesized and polymerized with acrylamide to furnish an ionic liquid-containing polymer, which was then used for the formation of a composite with iron-based metal-organic framework. The resultant composite was characterized with XRD, TGA, FE-SEM, FTIR, EDS and elemental mapping analyses and its catalytic activity was appraised for ultrasonic-assisted Knoevenagel condensation. The results confirmed that the prepared composite could promote the reaction efficiently to furnish the corresponding products in high yields in very short reaction times. Moreover, the composite exhibited high recyclability up to six runs. It was also established that the activity of the composite was higher compared to pristine metal-organic framework or polymer.

Quick removal of metronidazole from aqueous solutions using metal–organic frameworks

Two MOFs were assembled, characterized and investigated in detail as efficient adsorbents for removal of the metronidazole antibiotic. Adsorption isotherms and kinetic features were also studied.

Enhancement of aqueous stability of NH2-MIL-101(Fe) by hydrophobic grafting post-synthetic modification

The development of water-stable metal-organic frameworks is a critical issue for their photocatalysis applications in water treatment. A phenyl-ethyl side chain with low surface energy was grafted into NH₂-MIL-101(Fe) through a post-synthetic modification (PSM) method. As a result, a novel MIL-101(Fe)-1-(4-(ethyl)phenyl)urea (named MIL-101(Fe)-EPU) was synthesized. Basic morphology, crystal structure, and chemical bond features of MIL-101(Fe)-EPU were retained after PSM. Nitrogen X-ray photoelectron spectroscopy analysis confirmed the successful introduction of the phenyl-ethyl side chain, and this transformation increased its hydrophobicity and water stability. Contact angles of MIL-101(Fe)-EPU to water raised from 59.6 to 140.4°. And its structure maintained intact after 72 h water exposure, indicating higher stability than parent NH₂-MIL-101(Fe). In the photocatalysis reaction with visible light and oxidant donor (H₂O₂), MIL-101(Fe)-EPU demonstrated a degradation efficiency of tetrabromobisphenol A with a reaction rate at 0.0313 min^-1. The predominant reaction mechanism was OH·oxidation. The acid condition was beneficial for this photocatalysis reaction and high stability was observed. Besides, photocatalysis efficiency, crystal structure, and chemical structures were all retained in different actual water mediums, suggesting high adaptability of MIL-101(Fe)-EPU. In general, hydrophobic group grafting using a PSM method endows MIL-101(Fe)-EPU the potentiality as photocatalyst for organic contaminant elimination from water.

Iron-based metal-organic framework: Synthesis, structure and current technologies for water reclamation with deep insight into framework integrity

Water is a supreme requirement for the existence of life, the contamination from the point and non-point sources are creating a great threat to the water ecosystem. Advance tools and techniques are required to restore the water quality and metal-organic framework (MOFs) with a tunable porous structure, striking physical and chemical properties are an excellent candidate for it. Fe-based MOFs, which developed rapidly in recent years, are foreseen as most promising to overcome the disadvantages of traditional water depolluting practices. Fe-MOFs with low toxicity and preferable stability possess excellent performance potential for almost all water remedying techniques in contrast to other MOF structures, especially visible light photocatalysis, Fenton, and Fenton-like heterogeneous catalysis. Fe-MOFs become essential tool for water treatment due to their high catalytic activity, abundant active site and pollutant-specific adsorption. However, the structural degradation under external chemical, photolytic, mechanical, and thermal stimuli is impeding Fe-MOFs from further improvement in activity and their commercialization. Understanding the shortcomings of structural integrity is crucial for large-scale synthesis and commercial implementation of Fe-MOFs-based water treatment techniques. Herein we summarize the synthesis, structure and recent advancements in water remediation methods using Fe-MOFs in particular more attention is paid for adsorption, heterogeneous catalysis and photocatalysis with clear insight into the mechanisms involved. For ease of analysis, the pollutants have been classified into two major classes; inorganic pollutants and organic pollutants. In this review, we present for the first time a detailed insight into the challenges in employing Fe-MOFs for water remediation due to structural instability.

Experimental investigations into the irregular synthesis of iron(iii) terephthalate metal-organic frameworks MOF-235 and MIL-101

MOF-235(Fe) and MIL-101(Fe) are two well-studied metal-organic frameworks (MOFs) with dissimilar crystal structures and topologies. Previously reported syntheses of the former show that it has greatly varying surface areas, indicating a lack of phase purity of the products, i.e. the possible presence of both MOFs in the same sample. To find the reason for this, we have tested and modified the commonly used synthesis protocol of MOF-235(Fe), where a 3 : 5 molar ratio of iron(iii) ions and a terephthalic acid linker is heated in a 1 : 1 DMF : ethanol solvent at 80 °C for 24 h. Using XRD and BET surface area (SA_BET) measurements, we found that it is difficult to obtain a pure phase of MOF-235, as MIL-101 also appears to form during the solvothermal treatment. Comparison of the XRD peak height ratios of the synthesis products revealed a direct correlation between the MOF-235/MIL-101 content and surface area; more MOF-235 yields a lower surface area and vice versa. In general, using a larger (3 : 1) DMF : ethanol ratio than that reported in the literature and a stoichiometric (4 : 3) Fe(iii) : TPA ratio yields a nearly pure MOF-235 product (SA_BET = 295 m² g^-1, 67% yield). An optimized synthesis procedure was developed to obtain high-surface area MIL-101(Fe) (SA_BET > 2400 m² g^-1) in a large yield and at a previously unreported temperature (80 °C vs. previously used 110-150 °C). In situ X-ray scattering was utilized to investigate the crystallization of MOF-235 and MIL-101. At 80 °C, only MOF-235 formed and at 85 and 90 °C, only MIL-101 formed.

Composite of MOF and chitin as an efficient catalyst for photodegradation of organic dyes

A novel composite has been fabricated by using MOF and chitin as a natural and biocompatible compound. To this purpose, MOF was synthesized by using 2-aminoterephthalic acid and iron (III) chloride hexahydrate and then reacted with Cl-functionalized chitin. The resulting composite was characterized and utilized as a catalyst for degradation of methylene blue both in dark condition and under visible light irradiation. The results indicated superior catalytic activity under visible light irradiation. Furthermore, study of the reaction variables, including basicity, dye concentration and catalyst loading showed that the highest catalytic activity was achieved at basic condition. It was also found that both initial dye concentration and catalyst loading can affect the catalytic activity. To disclose the merits of the composite compared to its individual components, kinetic studies of the photo-degradation process in the presence of the composite, chitin and MOF have been performed. The results confirmed superior activity the composite compared to its components. The study of the mechanism of the reaction using scavengers confirmed that the created holes (h⁺) are the most effective species in the process of photocatalytic degradation of MB. Notably, the catalyst was recyclable and could be used for degradation of other dyes.

Introducing reticular chemistry into agrochemistry

For survival and quality of life, human society has sought more productive, precise, and sustainable agriculture. Agrochemistry, which solves farming issues in a chemical manner, is the core engine that drives the evolution of modern agriculture. To date, agrochemistry has utilized chemical technologies in the form of pesticides, fertilizers, veterinary drugs and various functional materials to meet fundamental demands from human society, while increasing the socio-ecological consequences due to inefficient use. Thus, more useful, precise, and designable scaffolding materials are required to support sustainable agrochemistry. Reticular chemistry, which weaves molecular units into frameworks, has been applied in many fields based on two cutting-edge porous framework materials, namely metal-organic frameworks (MOFs) and covalent-organic frameworks (COFs). With flexibility in composition, structure, and pore chemistry, MOFs and COFs have shown increasing functionalities associated with agrochemistry in the last decade, potentially introducing reticular chemistry as a highly accessible chemical toolbox into agrochemical technologies. In this critical review, we will demonstrate how reticular chemistry shapes the future of agrochemistry in the fields of farm sensing, agro-ecological preservation and reutilization, agrochemical formulations, smart indoor farming, agrobiotechnology, and beyond.

Zirconium(Ⅳ)-based metal-organic framework for determination of imidacloprid and thiamethoxam pesticides from fruits by UPLC-MS/MS

Zirconium(Ⅳ)-based metal-organic framework (MOF)-UiO-66-NH₂ was fabricated to adsorb the imidacloprid and thiamethoxam in fruit samples before analysis using UPLC-MS/MS. The UiO-66-NH₂ was confirmed by SEM, FTIR, and XRD. Key experimental parameters were investigated by response surface methodology (RSM). The desirability recovery of imidacloprid was 94.52% under optimum conditions (mount of adsorbent = 52.48 mg, volume of eluent = 5.18 mL, pH = 9, extraction time = 15 min). The desirability recovery of thiamethoxam was 93.57% under optimum conditions (mount of adsorbent = 50.58 mg, volume of eluent = 2.6 mL, pH = 5.65, extraction time = 11.94 min). Under the optimal conditions, the actual recovery of imidacloprid and thiamethoxam was 92.39% and 94.37%, respectively. Besides, the method was applied successfully to detect imidacloprid and thiamethoxam in different fruit samples. The results demonstrated that the UiO-66-NH₂ is an excellent adsorbent for the extraction imidacloprid and thiamethoxam from fruit samples.

Removal of Berberine from Wastewater by MIL-101(Fe): Performance and Mechanism

The water contamination from pharmaceuticals and personal care products (PPCPs) has attracted worldwide attention in recent years because of its threat to public health. Berberine is a typical anti-inflammatory medicine and berberine wastewater is difficult to be treated due to its high toxicity, poor biodegradability, and high acidity. Metal-organic frameworks would be a good choice to remove berberine from wastewater due to its advantages of high specific surface area, ultrahigh porosity, and structural and functional tunability. In this study, MIL-101(Fe) was synthesized and used for the removal of berberine from water. Experimental results indicated that MIL-101(Fe) showed promising characteristics when berberine was adsorbed in acidic wastewater. The high concentration of chloride in berberine wastewater could promote the adsorption of berberine by MIL-101(Fe). Fitting of batch equilibrium data showed that MIL-101(Fe) had a maximum adsorption capacity of 163.93 mg/g for berberine removal at pH 7, and the berberine sorption on MIL-101(Fe) followed the pseudo-second-order model. Furthermore, the associate mechanism for berberine removal was proposed by characterizing the material and theoretical calculation. The X-ray power diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) analysis showed that no chemical reaction occurred during the adsorption of berberine by MIL-101(Fe). Also, the theoretical calculation results indicated that π-π interactions may play the main role in the adsorption of berberine onto MIL-101(Fe). The findings of this study suggest that MIL-101(Fe) is a promising sorbent for berberine removal from wastewater.

An organic-inorganic hybrid nanomaterial composed of a Dowson-type (NH4)6P2Mo18O62 heteropolyanion and a metal-organic framework: synthesis, characterization, and application as an effective adsorbent for the removal of organic dyes

In this work, an inorganic-organic hybrid nanomaterial, P2Mo18/MIL-101(Cr), based on Wells-Dawson-type (NH4)6P2Mo18O62 polyoxometalate (abbreviated as P2Mo18) and the MIL-101(Cr) metal-organic framework was fabricated by the reaction of (NH4)6P2Mo18O62, Cr(NO3)3·9H2O and terephthalic acid under hydrothermal conditions. The as-prepared recyclable nanohybrid was fully characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR) equipped with energy dispersive X-ray microanalysis (EDX), field emission scanning electron microscopy (FE-SEM), Raman spectroscopy and Brunauer-Emmett-Teller (BET) specific surface area studies. All the analyses confirmed the successful insertion of P2Mo18O62 6- heteropolyanion within the cavities of MIL-101(Cr). The encapsulated MIL-101(Cr) showed a considerable decrease in both pore volume and surface area compared with MIL-101(Cr) due to incorporation of the very large Dowson-type polyoxometalate into the three-dimensional porous MIL-101(Cr). The nanohybrid had a specific surface area of 800.42 m2 g-1. The adsorption efficiency of this nanohybrid for removal of methylene blue (MB), rhodamine B (RhB), and methyl orange (MO) from aqueous solutions was evaluated. Surprisingly, the composite not only presented a high adsorption capacity of 312.5 mg g-1 for MB, but also has the ability to rapidly remove 100% MB from a dye solution of 50 mg L-1 within 3 min. These results confirmed that this adsorbent is applicable in a wide pH range of 2-10. The nanohybrid showed rapid and selective adsorption for cationic MB and RhB dyes from MB/MO, MB/RhB, MO/RhB and MB/MO/RhB mixed dye solutions. The equilibrium adsorption data were better fitted by the Langmuir isotherm. Kinetics data indicate that the adsorption of the dye follows a pseudo-second order kinetics model. Also, this material could be effortlessly separated and recycled without any structural modification. Accordingly, it is an efficient adsorbent for removing cationic dyes.