Nitrogen-doped magnetic carbon nanoparticles as catalyst supports for efficient recovery and recycling

Palladium Nanoparticle-Decorated Porous Metal-Organic-Framework (Zr)@Guanidine: Novel Efficient Catalyst in Cross-Coupling (Suzuki, Heck, and Sonogashira) Reactions and Carbonylative Sonogashira under Mild Conditions

A novel heterogeneous Zr-based metal-organic framework containing an amino group functionalized with nitrogen-rich organic ligand (guanidine), through a step-by-step post synthesis modification approach, was successfully modified by the stabilization of palladium metal nanoparticles on the prepared UiO-66-NH₂ support in order to synthesize the Suzuki-Murray, Mizoroki-Heck, and copper-free Sonogashira reactions and also the carbonylative Sonogashira reaction incorporating H₂O as a green solvent under mild conditions. This newly synthesized highly efficient and reusable UiO-66-NH₂@cyanuric chloride@guanidine/Pd-NPs reported catalyst has been utilized to increase anchoring palladium onto the substrate with the aim of altering the construction of the intended synthesis catalyst to form the C-C coupling derivatives. Several strategies, including X-ray diffraction, Fourier transform infrared, scanning electron microscopy, Brunauer-Emmett-Teller, transmission microscopy electron, thermogravimetric analysis, inductively coupled plasma, energy-dispersive X-ray, and elemental mapping analyzes, were used to indicate the successful preparation of the UiO-66-NH₂@cyanuric chloride@guanidine/Pd-NPs. In these reactions, the UiO-66-NH₂-supported Pd-NPs illustrated superior performances compared to their catalyst, revealing the benefits of providing nanocatalysts. As a result, the proposed catalyst is favorable in a green solvent, and also, the outputs are accomplished with good to excellent outputs. Furthermore, the suggested catalyst represented very good reusability with no remarkable loss in activity up nine sequential runs.

Highly efficient removal of quinolones by using the easily reusable MOF derived-carbon

As anthropogenic antibiotics, quinolones, e.g., ofloxacin have adverse impacts on ecological systems and human heaths. The removal of quinolones is of great importance, and adsorption techniques have been widely used to remove this hazardous contaminant. However, a robust and easy-operating adsorbent is still emergently required due to the complex chemical structure of quinolones. In this study, we successfully synthesized the promising metallic carbons (MCs) containing carbon nanotubes and cobalt nanoparticles by carbonizing Zn/Co-ZIF at 900 °C. Three different molar ratios of Co and Zn were applied to optimize the adsorption capacity on ofloxacin (OFL). Results showed MC with molar ratio of Co and Zn at 3:1 (Co-CNT/NPC_3/1) achieved the maximal adsorption capacity to 118.3 mg g^-1. Its adsorption performance was satisfied in the pH range from 5 to 9 and ionic strengths at 0.01 M. The main mechanisms for these adsorptions were identified as electrostatic attraction, metal coordination and π-π EDA. Removal efficiencies of quinolones higher than 68 mg g^-1 indicated the strong feasibility of this adsorbent for wastewater treatments. The regeneration of Co-CNT/NPC_3/1 at 600 °C allowed its at least 4-time reusability and its magnetic property enabled external magnets to recycle it from real environments.

A new procedure for the preparation of 3,4-dihydropyrimidin-2(1H)-one and octahydroquinazolinone derivatives catalyzed by SCMNPs@CA-EA-SO3H under solvent-free conditions

Abstract:

Catalyzed with SCMNPs@CA-EA-SO3H, as a green and heterogeneous solid acid catalyst, 3,4-dihydropyrimidin-2(1H)-one and octahydroquinazolinone derivatives were obtained in high-to-excellent yields and in short reaction times via the one-pot multi-component condensation of ethyl acetoacetate or dimedone, urea, and aldehyde compounds under solvent-free conditions. More importantly, the green catalytic system could be easily collected from the reaction solution utilizing an external magnet and reused for five runs with a negligible decrease in yields and reaction rate.

A review of metal organic framework (MOFs)-based materials for antibiotics removal via adsorption and photocatalysis

Antibiotic abuse has led to serious water pollution and severe harm to human health; therefore, there is an urgent need for antibiotic removal from water sources. Adsorption and photodegradation are two ideal water treatment methods because they are cheap, simple to operate, and reusable. Metal organic frameworks (MOFs) are excellent adsorbents and photocatalysts because of their high porosity, adaptability, and good crystal form. The aim of this study is to suggest ways to overcome the limitations of adsorption and photocatalysis treatment methods by reviewing previous applications of MOFs to antibiotic adsorption and photocatalysis. The different factors influencing these processes are also discussed, as well as the various adsorption and photocatalysis mechanisms. This study provides a valuable resource for researchers intending to use MOFs to remove antibiotics from water bodies.

Bottom-up synthesis of nitrogen-doped nanocarbons by a combination of metal catalysis and a solution plasma process

We aimed to develop the bottom-up synthesis of nanocarbons with specific functions from molecules without any leaving group, halogen atom and boronic acid, by employing a metal catalyst under solution plasma irradiation. Pyridine was used as a source of carbon. In the presence of a Pd catalyst, the plasma treatment enabled the synthesis of N-doped carbons with a pyridinic configuration, which worked as an active catalytic site for the oxygen reduction reaction.

Understanding Heteroatom-Mediated Metal–Support Interactions in Functionalized Carbons: A Perspective Review

Carbon-based materials show unique chemicophysical properties, and they have been successfully used in many catalytic processes, including the production of chemicals and energy. The introduction of heteroatoms (N, B, P, S) alters the electronic properties, often increasing the reactivity of the surface of nanocarbons. The functional groups on the carbons have been reported to be effective for anchoring metal nanoparticles. Although the interaction between functional groups and metal has been studied by various characterization techniques, theoretical models, and catalytic results, the role and nature of heteroatoms is still an object of discussion. The aim of this review is to elucidate the metal–heteroatoms interaction, providing an overview of the main experimental and theoretical outcomes about heteroatom-mediated metal–support interactions. Selected studies showing the effect of heteroatom–metal interaction in the liquid-phase alcohol oxidation will be also presented.

Pd nanoparticles immobilized on carbon nanotubes with a polyaniline coaxial coating for the Heck reaction: coating thickness as the key factor influencing the efficiency and stability of the catalyst

Pd/PANI@CNTs were synthesized using a low-cost and simple method. The thickness of the PANI layer is the key in determining the stability of the catalyst in the Heck reaction.

Controllable synthesis of graphitic carbon nitride nanomaterials for solar energy conversion and environmental remediation: the road travelled and the way forward

This review discusses advances in the synthesis and design of g-C₃N₄-based nanomaterials and their various photocatalytic and photoredox applications.

Nanostructured mesophase electrode materials: modulating charge-storage behavior by thermal treatment

3D nanostructured carbonaceous electrode materials with tunable capacitive phases were successfully developed using graphene/particulate polypyrrole (PPy) nanohybrid (GPNH) precursors without a separate process for incorporating heterogeneous species. The electrode material, namely carbonized GPNHs (CGPNHs) featured a mesophase capacitance consisting of both electric double-layer (EDL) capacitive and pseudocapacitive elements at the molecular level. The ratio of EDL capacitive element to pseudocapacitive element (E-to-P) in the mesophase electrode materials was controlled by varying the PPy-to-graphite weight (P_w/G_w) ratio and by heat treatment (T_H), which was demonstrated by characterizing the CGPNHs with elemental analysis, cyclic voltammetry, and a charge/discharge test. The concept of the E-to-P ratio (EPR) index was first proposed to easily identify the capacitive characteristics of the mesophase electrode using a numerical algorithm, which was reasonably consistent with the experimental findings. Finally, the CGPNHs were integrated into symmetric two-electrode capacitor cells, which rendered excellent energy and power densities in both aqueous and ionic liquid electrolytes. It is anticipated that our approach could be widely extended to fabricating versatile hybrid electrode materials with estimation of their capacitive characteristics.

Synthesis of flower-like magnetite nanoassembly: Application in the efficient reduction of nitroarenes

A facile approach for the synthesis of magnetite microspheres with flower-like morphology is reported that proceeds via the reduction of iron(III) oxide under a hydrogen atmosphere. The ensuing magnetic catalyst is well characterized by XRD, FE-SEM, TEM, N₂ adsorption-desorption isotherm, and Mössbauer spectroscopy and explored for a simple yet efficient transfer hydrogenation reduction of a variety of nitroarenes to respective anilines in good to excellent yields (up to 98%) employing hydrazine hydrate. The catalyst could be easily separated at the end of a reaction using an external magnet and can be recycled up to 10 times without any loss in catalytic activity.

Application of polydopamine sulfamic acid-functionalized magnetic Fe3O4 nanoparticles (Fe3O4@PDA-SO3H) as a heterogeneous and recyclable nanocatalyst for the formylation of alcohols and amines under solvent-free conditions

Herein, a highly effective and solvent-free Fe₃O₄@PDA-SO₃H catalyzed technique was advanced for N-formylation of alcohols, phenols and amines with ethyl formate.

A green direct preparation of a magnetic ordered mesoporous carbon catalyst containing Fe–Pd alloys: application to Suzuki–Miyaura reactions in propane-1,2-diol

A mesoporous carbon containing Fe–Pd alloys showed excellent activity for Suzuki–Miyaura couplings using tiny amounts of Pd and afforded Pd-free products after reaction.

Plant leaves as natural green scaffolds for palladium catalyzed Suzuki-Miyaura coupling reactions

This work presents a novel approach of using natural plant leaf surfaces having intricate hierarchical structures as scaffolds for Pd nanoparticles and demonstrated it as a Green dip catalyst for Suzuki-Miyaura coupling reactions in water. The influence of the topographical texture of the plant leaves on the deposition and catalytic properties of Pd nanoparticles are presented and discussed. The catalytic activity can be correlated to the surface texture of the leaves, wherein it has been found that the micro/nanostructures present on the surface strongly influence the assembly and entrapment of the nanoparticles, and thereby control aggregation and leaching of the catalysts. This approach can provide insights for the future design and fabrication of bioinspired supports for catalysis, based on replication of leaf surfaces.

Preparation of raspberry-like γ-Fe2O3/crackled nitrogen-doped carbon capsules and their application as supports to improve catalytic activity

In this manuscript, we have introduced a novel method to improve the catalytic activity of metal nanoparticles via optimizing the support structure. To this end, raspberry-like γ-Fe₂O₃/crackled nitrogen-doped carbon (CNC) capsules were prepared by a two-step method. Compared with traditional magnetic capsules, in γ-Fe₂O₃/CNC capsules, the γ-Fe₂O₃ nanoparticles were embedded in a CNC shell; therefore, they neither occupied the anchoring sites for metal nanoparticles nor came into contact with them, which was beneficial for increasing the metal nanoparticle loading. Numerous tiny cracks appeared on the porous CNC shell, which effectively improved the mass diffusion and transport in catalytic reactions. Additionally, the coordination interaction could be generated between the precursor metal ions and doped-nitrogen atoms in the capsule shell. With the help of these structural merits, γ-Fe₂O₃/CNC capsules were ideal supports for Pd nanoparticles, because they were beneficial for improving the Pd loading, reducing the nanoparticle size, increasing their dispersity and maximizing the catalytic performance of Pd nanoparticles anchored on the inner shell surface. As expected, γ-Fe₂O₃/CNC@Pd catalysts exhibited a dramatically enhanced catalytic activity towards hydrophilic 4-nitrophenol and hydrophobic nitrobenzene. The reaction rate constant k was compared with recent work and the corresponding reference samples. Moreover, they could be easily recycled by using a magnet and reused without an obvious loss of catalytic activity.

Pd nanoparticles deposited on Isoniazid grafted multi walled carbon nanotubes: synthesis, characterization and application for Suzuki reaction in aqueous media

The prepared Isoniazide-MWCNTs were used to deposition of Pd NPs as novel nanocatalyst. The catalyst showed high activity in Suzuki coupling reaction of aryl halides (X = I, Br, Cl).

Indirect conversion of ambient pressure CO2 into oxazolidin-2-ones by a copper-based magnetic nanocatalyst

A magnetically recyclable Cu-based catalytic system was developed for the indirect conversion of ambient pressure of CO₂ into oxazolidin-2-ones.

Palladium stabilized by 3,4-dihydroxypyridine-functionalized magnetic Fe3O4nanoparticles as a reusable and efficient heterogeneous catalyst for Suzuki reactions

A Pd supported on 3,4-dihydroxypyridine (Py)-functionalized Fe₃O₄(Fe₃O₄/Py/Pd) hybrid material has been synthesized for the first time.

Synthesis and biological evaluation of new pyranopyridine derivatives catalyzed by guanidinium chloride-functionalized γ-Fe2O3/HAp magnetic nanoparticles

Herein, we described the synthesis of γ-Fe₂O₃@HAP-GndCl MNPs as an efficient and recyclable nanocatalyst for synthesis of new pyranopyridine derivatives under solvent-free condition and then evaluated for theirs antioxidant and antifungal activities.

Green synthesis of palladium nanoparticles via branched polymers: a bio-based nanocomposite for C–C coupling reactions

Renewable and sustainable CMH was the natural ligand for CMH–Pd(0) nanocomposite which was as an efficient and recyclable catalyst for Heck reaction.

Synthesis and characterization of Bi(iii) immobilized on triazine dendrimer-stabilized magnetic nanoparticles: a reusable catalyst for the synthesis of aminonaphthoquinones and bis-aminonaphthoquinones

A novel method for synthesis of aminonaphthoquinone derivatives using Fe₃O₄@TDSN–Bi(iii) is reported.