Environmental pollution of phosphorus is becoming increasingly concerning, and phosphate removal from water has become an important issue for controlling eutrophication. Modified metal-organic framework (MOF) materials, such as UiO-66-NH2, are promising adsorbents for phosphate removal in aquatic environments due to their high specific surface area, high porosity, and open active metal sites. In this study, a millimeter-sized alginate/UiO-66-NH2 composite hydrogel modified by polyethyleneimine (UiO-66-NH2/SA@PEI) was prepared. The entrapping of UiO-66-NH2 in the alginate microspheres and its modification with PEI facilitate easy separation in addition to enhanced adsorption properties. The materials were characterized by SEM, FTIR, XRD, and BET. Static, dynamic, and cyclic adsorption experiments were conducted under different pH, temperature, adsorbent dosage, and initial concentration conditions to assess the phosphate adsorption ability of UiO-66-NH2/SA@PEI. Under optimal conditions of 65 °C and pH = 2, 0.05 g UiO-66-NH2/SA@PEI adsorbed 68.75 mg/g, and the adsorption rate remained at 99% after five cycles of UiO-66-NH2/SA@PEI. These results suggest that UiO-66-NH2/SA@PEI composite materials can be used as an effective adsorbent for phosphate removal from wastewater.

Metal-organic frameworks (MOFs), particularly UiO-66-NH2, are employed as catalysts in many industrial catalyst applications. As converting catalysts into thin film significantly increases their catalytic properties, we report a general approach to synthesizing MOF thin films (UiO-66-Pyca-CuO). First, functionalization of UiO-66-NH2 was done with 3-pyridine carboxaldehyde by the postsynthesis method, and then, UiO-66-Pyca was entangled on the surface of copper oxide nanoparticles with a modern strategy (MOF thin film). The morphology and structure of the synthesized UiO-66-Pyca-CuO were determined by using X-ray diffraction, Fourier transform infrared, field-emission scanning electron microscopy, energy-dispersive analysis of X-ray, inductively coupled plasma-mass spectrometry, elemental analyses of CHNOS, temperature-programmed desorption of ammonia, Brunauer-Emmett-Teller, and X-ray photoelectron spectroscopy. We studied the catalytic action of the UiO-66-Pyca-CuO thin film in the synthesis of α-aminonitriles via Strecker reaction. Our studies show that this catalysis can be a suitable catalyst in the synthesis of α-aminonitriles because of having advantages such as using the solvent being environmentally friendly, easy separation of the catalyst (only by picking up the MOF thin film from inside the solution), the reaction at room temperature, high yield, and reusability.

Enrichment and quantification of sugar phosphates (SPx) in biological samples were of great significance in biological medicine. In this work, a series of zirconium-based metal-organic frameworks (MOFs) with different degrees of defects, namely, HP-UiO-66-NH2-X, were synthesized using acetic acid as a modulator and were utilized as high-capacity adsorbents for the adsorption of SPx in biological samples. The results indicated that the addition of acetic acid altered the morphology of HP-UiO-66-NH2-X, with corresponding changes in pore size (3.99-9.28 nm) and specific surface area (894.44-1142.50 m2·g-1). HP-UiO-66-NH2-10 showed the outstanding performance by achieving complete adsorption of all four SPx using only 80 μg of the adsorbent. The excellent adsorption efficiency of HP-UiO-66-NH2-10 was also obtained with a wide pH range and short adsorption time (10 min). Adsorption experiments demonstrated that the adsorption process involved chemical adsorption and multilayer adsorption. By utilizing X-ray photoelectron spectroscopy and density functional theory to explain the adsorption mechanism, it was found that various interactions (including coordination, hydrogen bonding, and electrostatic interactions) collectively contributed to the exceptional adsorption capability of HP-UiO-66-NH2-10. Those results indicated that the defect strategy not only increased the specific surface area and pore size, providing additional adsorption sites, but also reduced the adsorption energy between HP-UiO-66-NH2-10 and SPx. Moreover, HP-UiO-66-NH2-10 showed a low limit of detection (0.001-0.01 ng·mL-1), high precision (<13.77%), and accuracy (80.10-111.83%) in serum, liver, and cells, good stability, high selectivity (SPx/glucose, 1:100 molar ratio), and high adsorption capacity (292 mg·g-1 for SPx). The practical detection of SPx from human serum was also verified, prefiguring the great potentials of defective zirconium-based MOFs for the enrichment and detection of SPx in the biological medicine.

The need to develop green and cost-effective industrial catalytic processes has led to growing interest in preparing more robust, efficient, and selective heterogeneous catalysts at a large scale. In this regard, microwave-assisted synthesis is a fast method for fabricating heterogeneous catalysts (including metal oxides, zeolites, metal-organic frameworks, and supported metal nanoparticles) with enhanced catalytic properties, enabling synthesis scale-up. Herein, the synthesis of nanosized UiO-66-NH2 was optimized via a microwave-assisted hydrothermal method to obtain defective matrices essential for the stabilization of metal nanoparticles, promoting catalytically active sites for hydrogenation reactions (760 kg·m-3·day-1 space time yield, STY). Then, this protocol was scaled up in a multimodal microwave reactor, reaching 86% yield (ca. 1 g, 1450 kg·m-3·day-1 STY) in only 30 min. Afterward, Pd nanoparticles were formed in situ decorating the nanoMOF by an effective and fast microwave-assisted hydrothermal method, resulting in the formation of Pd@UiO-66-NH2 composites. Both the localization and oxidation states of Pd nanoparticles (NPs) in the MOF were achieved using high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and X-ray photoelectron spectroscopy (XPS), respectively. The optimal composite, loaded with 1.7 wt % Pd, exhibited an extraordinary catalytic activity (>95% yield, 100% selectivity) under mild conditions (1 bar H2, 25 °C, 1 h reaction time), not only in the selective hydrogenation of a variety of single alkenes (1-hexene, 1-octene, 1-tridecene, cyclohexene, and tetraphenyl ethylene) but also in the conversion of a complex mixture of alkenes (i.e., 1-hexene, 1-tridecene, and anethole). The results showed a powerful interaction and synergy between the active phase (Pd NPs) and the catalytic porous scaffold (UiO-66-NH2), which are essential for the selectivity and recyclability.

Significant progress has been made in designing advanced membranes; however, persistent challenges remain due to their reduced permeation rates and a propensity for substantial fouling. These factors continue to pose significant barriers to the effective utilization of membranes in the separation of oil-in-water emulsions. Metal-organic frameworks (MOFs) are considered promising materials for such applications; however, they encounter three key challenges when applied to the separation of oil from water: (a) lack of water stability; (b) difficulty in producing defect-free membranes; and (c) unresolved issue of stabilizing the MOF separating layer on the ceramic membrane (CM) support. In this study, a defect-free hydrolytically stable zirconium-based MOF separating layer was formed through a two-step method: first, by in situ growth of UiO-66-NH2 MOF into the voids of polydopamine (PDA)-functionalized CM during the solvothermal process, and then by facilitating the self-assembly of UiO-66-NH2 with PDA using a pressurized dead-end assembly. A stable MOF separating layer was attained by enriching the ceramic support with amines and hydroxyl groups using PDA, which assisted in the assembly and stabilization of UiO-66-NH2. The PDA-s-UiO-66-NH2-CM membrane displayed air superhydrophilicity and underwater superoleophobicity, demonstrating its oil resistance and high antifouling behavior. The PDA-s-UiO-66-NH2-CM membrane has shown exceptionally high permeability and separation capacity for challenging oil-in-water emulsions. This is attributed to numerous nanochannels from the membrane and its high resistance to oil adhesion. The membranes showed excellent stability over 15 continuous test cycles, which indicates that the developed MOFs separating layers have a low tendency to be clogged by oil droplets during separation. Machine learning-based Gaussian process regression (GPR) models as nonparametric kernel-based probabilistic models were employed to predict the performance efficiency of the PDA-s-UiO-66-NH2-CM membrane in oil-in-water separation. The outcomes were compared with the support vector machine (SVM) and decision tree (DT) algorithm. This efficiency includes various metrics related to its separation accuracy, and the models were developed through feature engineering to identify and utilize the most significant factors affecting the membrane\'s performance. The results proved the reliability of GPR optimization with the highest prediction accuracy in the validation phase. The average percentage increase of the GPR model compared to the SVM and DT model was 6.11 and 42.94%, respectively.

The development of capsules with additives that can be added to polymers during extrusion processing can lead to advances in the manufacturing of textile fabrics with improved and durable properties. In this work, caffeine (CAF), which has anti-cellulite properties, has been encapsulated by liquid-assisted milling in zirconium-based metal-organic frameworks (MOFs) with different textural properties and chemical functionalization: commercial UiO-66, UiO-66 synthesized without solvents, and UiO-66-NH2 synthesized in ethanol. The CAF@MOF capsules obtained through the grinding procedure have been added during the extrusion process to recycled polyamide 6 (PA6) and to a biopolymer based on polylactic acid (PLA) to obtain a load of approximately 2.5 wt% of caffeine. The materials have been characterized by various techniques (XRD, NMR, TGA, FTIR, nitrogen sorption, UV-vis, SEM, and TEM) that confirm the caffeine encapsulation, the preservation of caffeine during the extrusion process, and the good contact between the polymer and the MOF. Studies of the capsules and PA6 polymer+capsules composites have shown that release is slower when caffeine is encapsulated than when it is free, and the textural properties of UiO-66 influence the release more prominently than the NH2 group. However, an interaction is established between the biopolymer PLA and caffeine that delays the release of the additive.

Thiols are essential functional groups imparting unique properties, such as reactivity and selectivity, to many vital enzymes and biomolecules. The integration of electronically soft thiol groups within metal-organic frameworks (MOFs) yields elevated reactivity and a pronounced affinity for soft metal ions. However, the scarcity of thiol-based ligands and synthetic challenges hinder the advancement of thiol-based MOFs. To bypass the difficulties of synthesizing thiol MOFs by a direct reaction between thiol-based ligands and corresponding metal salts, postsynthetic modification (PSM) of MOFs is an efficient strategy to introduce thiol functionality. Herein, we have introduced Ag nanoparticles in postsynthetically modified thiol MOFs UiO-66-NH-SH (1) (synthesized by reaction between UiO-66-NH2 and thioglycolic acid) and UiO-66-NH-SH (2) (synthesized by reaction between UiO-66-NH2 and 3-mercaptopropionic acid) to synthesize a series of heterogeneous catalysts for CO2 fixation. Catalysts Cat 1-2 and Cat 3 - 4 were synthesized from UiO-66-NH-SH (1) and UiO-66-NH-SH (2), respectively, by using varying concentrations of silver (AgNO3). Catalyst Ag@UiO-66-NH-SH (1) (Ag = 3.45%; namely Cat 2) shows the highest efficiency for the catalytic conversion of propargylic alcohol and terminal epoxide to the corresponding cyclic carbonates. Finally, a rationalized reaction mechanism is proposed by correlating our results with the current literature. This work presents a viable strategy to utilize the thiol functionality of MOFs (avoiding the complexities associated with synthesizing thiol MOFs directly from thiol ligands) as a platform for introducing catalytically active metal centers and applying them as a heterogeneous catalyst for CO2 fixation reactions.

Enormous efforts have been made to convert biomass to liquid fuels and products catalytically. Long molecules with a suitable structure are ideal precursors for fuels and value-added products. Here, a C21 oxygenate was synthesized for the first time in one step through aldol condensation of furfural and acetone over the amine-functionalized zirconium-based metal-organic framework (MOF), UiO-66-NH2. Structural changes of UiO-66-NH2 were investigated to improve the yield and evaluate the role of the ligand, cluster node, defectiveness, modulator, surface area, and textural properties on the product distribution. We demonstrate the possibility of making long-chain oxygenates without using vegetable oil-derived fatty acids toward 100% waste biomass-derived renewable fuels, lubricants, and surfactants.

The utilization of dye adsorption through metal-organic frameworks represents an eco-friendly and highly effective approach in real water treatment. Here, ultrasound assisted adsorption approach was employed for the remediation of three dyes including methylene blue (MB), malachite green (MG), and congo red (CR) from real water samples using zirconium(IV)-based adsorbent (UiO-66-NH2). The adsorbent was characterized for structural, elemental, thermal and morphological features through XRD, XPS, FTIR, thermogravimetric analysis, SEM, BET , and Raman spectroscopy. The adsorption capacity of adsorbent to uptake the pollutants in aqueous solutions was investigated under different experimental conditions such as amount of UiO-66-NH2 at various contact durations, temperatures, pH levels, and initial dye loading amounts. The maximum removal of dyes under optimal conditions was found to be 938, 587, and 623 mg g-1 towardMB, MG, and CR, respectively. The adsorption of the studied dyes on the adsorbent surface was found to be a monolayer and endothermic process. The probable mechanism for the adsorption was chemisorption and follows pseudo-second-order kinetics. From the findings of regeneration studies, it was deduced that the adsorbent can be effectively used for three consecutive cycles without any momentous loss in its adsorption efficacy. Furthermore, UiO-66-NH2 with ultrasound-assisted adsorption might help to safeguard the environment and to develop new strategies for sustainability of natural resources.

Bone tumor patients often encounter challenges associated with cancer cell residues and bone defects postoperation. To address this, there is an urgent need to develop a material that can enable tumor treatment and promote bone repair. Metal-organic frameworks (MOFs) have attracted the interest of many researchers due to their special porous structure, which has great potential in regenerative medicine and drug delivery. However, few studies explore MOFs with dual antitumor and bone regeneration properties. In this study, we investigated amino-functionalized zirconium-based MOF nanoparticles (UiO-66-NH2 NPs) as bifunctional nanomaterials for bone tumor treatment and osteogenesis promotion. UiO-66-NH2 NPs loading with doxorubicin (DOX) (DOX@UiO-66-NH2 NPs) showed good antitumor efficacy both in vitro and in vivo. Additionally, DOX@UiO-66-NH2 NPs significantly reduced lung injury compared to free DOX in vivo. Interestingly, the internalized UiO-66-NH2 NPs notably promoted the osteogenic differentiation of preosteoblasts. RNA-sequencing data revealed that PI3K-Akt signaling pathways or MAPK signaling pathways might be involved in this enhanced osteogenesis. Overall, UiO-66-NH2 NPs exhibit dual functionality in tumor treatment and bone repair, making them highly promising as a bifunctional material with broad application prospects.