Polar functional groups anchored to a 2D MOF template for the stabilization of Pd(0) nps for the catalytic C-C coupling reaction

Flexible Linker Spacer Length Modulation in Cd-Based Metal-Organic Frameworks: Impact on Polarity and Sequestration Abilities

The heightening concerns over an outbreak of hazardous radioiodine from nuclear waste and carbon dioxide emissions from fossil fuels have restricted access to clean water and air. In this work, three Cd-MOFs (1-3) are self-assembled under environment-friendly conditions using i) a polypyridyl linker spanned by a flexible poly(methylene) spacer, and ii) a bent dicarboxylate linker. With a change in the length of the flexible methylene spacer, the dimensionality of the MOFs is tuned between 3D (1) and 2D (2 and 3). The microscopic images reveal that 1 displays larger particle sizes and a more pronounced morphology compared to 2 and 3. These MOFs show high thermal stability (up to 300 °C) and wettability. A controlled polar feature of 1-3 is utilized to achieve a high uptake capacity of iodine (I2 or I3 -) from water bodies (2.46-2.37 g g-1) and vapor (3.31-2.65 g g-1). With remarkable CO2 uptake by 1-3, the sorbate CO2 is further fixated into market-value products in quantitative conversions and atom economy under room temperature and solvent-free conditions. A comprehensive theoretical support is provided by configurational biased Monte Carlo (CBMC) simulations to reveal the exact locale and binding energies of the sorbates (I2, CO2, and epoxide) toward these MOFs.

Carboxyethylsilanetriol-Functionalized Al-MIL-53-Supported Palladium Catalyst for Enhancing Suzuki-Miyaura Cross-Coupling Reaction

The application of metal-organic frameworks (MOFs) has attracted increasing attention in organic synthesis. The modification of MOFs can efficiently tailor the structure and improve the property for meeting ongoing demand in various applications, such as the alteration of gas adsorption and separation, catalytic activity, stability, and sustainability or reusability. In this study, carboxyethylsilanetriol (CEST) disodium salt was used as a dual-functional ligand for modified Al-MIL-53 to fabricate CEST-functionalized Al-MIL-53 samples through a hydrothermal reaction of aluminum nitrate, terephthalic acid, and CEST disodium salt by varying the molar ratio of CEST to terephthalic acid and keeping a constant molar ratio of Al3+/-COOH of 1:1. The structure, composition, morphology, pore feature, and stability were characterized by XRD, different spectroscopies, electron microscopy, N2 physisorption, and thermogravimetric analysis. With increasing CEST content, CEST-Al-MIL-53 still preserves an Al-MIL-53-like structure, but the microstructure changed compared with pure Al-MIL-53 due to the integration of CEST. Such a CEST-Al-MIL-53 was used as the support to load Pd particles and afford a catalyst Pd/CEST-Al-MIL-53 for Suzuki-Miyaura C-C cross-coupling reaction of aryl halides and phenylboronic acid under basic conditions. The resulting Pd/CEST-Al-MIL-53 showed a high catalytic activity compared with Pd/Al-MIL-53, due to the nanofibrous structure of silicon species-integrated CEST-Al-MIL-53. The nanofiber microstructure undergoes a remarkable transformation into intricate 3D cross-networks during catalytic reaction, which enables the leachable Pd particles to orientally redeposit and inlay into these networks as the monodisperse spheres and thereby effectively preventing Pd particles from aggregation and leaching, therefore demonstrating a high catalytic performance, long-term stability, and enhanced reusability. Obviously, the integration of CEST into MOFs can effectively prevent the leaching of active Pd species and ensure the re-deposition during catalysis. Moreover, catalytic performance strongly depended on catalyst dosage, temperature, time, solvent, and the type of the substituted group on benzene ring. This work further extends the catalytic application of hybrid metal-organic frameworks.

Recent advances in heterogeneous porous Metal-Organic Framework catalysis for Suzuki-Miyaura cross-couplings

Suzuki-Miyaura coupling (SMC), a crucial C-C cross-coupling reaction, is still associated with challenges such as high synthetic costs, intricate work-ups, and contamination with homogeneous metal catalysts. Research intensely focuses on strategies to convert homogeneous soluble metal catalysts into insoluble powder solids, promoting heterogeneous catalysis for easy recovery and reuse as well as for exploring greener reaction protocols. Metal-Organic Frameworks (MOFs), recognized for their high surface area, porosity, and presence of transition metals, are increasingly studied for developing heterogeneous SMC. The molecular fence effect, attributed to MOF surface functionalization, helps preventing catalyst deactivation by aggregation, migration, and leaching during catalysis. Recent reports demonstrate the enhanced catalytic activity, selectivity, stability, application scopes, and potential of MOFs in developing greener heterogeneous synthetic methodologies. This review focuses on the catalytic applications of MOFs in SMC reactions, emphasizing developments after 2016. It critically examines the synthesis and incorporation of active metal species into MOFs, focusing on morphology, crystallinity, and dimensionality for catalytic activity induction. MOF catalysts are categorized based on their metal nodes in subsections, with comprehensive discussion on Pd incorporation strategies, catalyst structures, optimal SMC conditions, and application scopes, concluding with insights into challenges and future research directions in this important emerging area of MOF applications.

SU-101: a Bi(III)-based metal-organic framework as an efficient heterogeneous catalyst for the CO2 cycloaddition reaction

A non-porous version of SU-101 (herein n-SU-101) was evaluated for the CO2 cycloaddition reaction. The findings revealed that open metal sites (Bi3+) are necessary for the reaction. n-SU-101 displays a high styrene oxide conversion of 96.6% under mild conditions (3 bar and 80 °C). The catalytic activity of n-SU-101 demonstrated its potential application for the cycloaddition of CO2 using styrene oxide.

Emerging Two-Dimensional-Based Nanostructured Catalysts: Applications in Sustainable Organic Transformations

The extension of green and sustainable materials in the preparation of heterogeneous catalysts for organic transformations has increased over the past few decades. Because of their unique and intriguing physical and chemical properties, two-dimensional (2D) nanostructured materials have attracted widespread attention and have been used in a variety of applications, such as catalysis, electronics, and energy storage. A promising pathway to enhance the performance of 2D nanomaterials is their coupling with other functional materials to form heterogeneous or hybrid structures. Herein, we discuss the use of 2D-based nanostructured catalysts for enhancing organic transformations and highlight selected examples to demonstrate the synthesis, advantages, challenges, efficiency, and reusability of the introduced heterogeneous catalysts for cross-coupling and reduction reactions.

New Palladium - ZrO2 Nano-Architectures from Thermal Transformation of UiO-66-NH2 for Carbonylative Suzuki and Hydrogenation Reactions

The new nanocomposites, Pd/C/ZrO₂ , PdO/ZrO_2, and Pd/PdO/ZrO₂ , were prepared by thermal conversion of Pd@UiO-66-Zr-NH₂ (MOF) in nitrogen or air atmosphere. The presence of Pd nanoparticles, uniformly distributed on the ZrO₂ or C/ZrO₂ matrix, was evidenced by transmission electron microscopy, scanning electron microscopy (SEM), Raman and X-ray Photoelectron Spectroscopy (XPS) methods. All pyrolysed composites retained the shape of the MOF template. They catalyze carbonylative Suzuki coupling under 1 atm CO with an efficiency significantly higher than the original Pd@UiO-66-Zr-NH₂ . The most active PdO/ZrO₂ composite, formed benzophenone with TOF up to 1600 h^-1 , while by using Pd@UiO-66-Zr-NH₂ , much lower TOF values, 51-95 h^-1 , were achieved. After the reaction, PdO/ZrO₂ was recovered with the same composition and catalytic activity. Very good results were also obtained in the transfer hydrogenation of benzophenones to alcohols with Pd/C/ZrO₂ and PdO/ZrO₂ catalysts under microwave irradiation.

Crystal structure of the coordination polymer catena-poly[(1,2-di(pyridin-4-yl)ethane-κN)-(μ2-2-nitroisophthalato-κ2O:O′)zinc(II)], C20H17N3O7Zn

C20H17N3O7Zn, monoclinic, P21/n (no. 14), a = 10.4368(3) Å, b = 15.1527(5) Å, c = 12.9007(3) Å, β = 101.900(3)°, V = 1996.36(10) Å3, Z = 4, Rgt(F) = 0.0410, wRref(F2) = 0.0898, T = 293(2) K.