Immobilization on a Nanomagnetic Co/C Surface Using ROM Polymerization: Generation of a Hybrid Material as Support for a Recyclable Palladium Catalyst

A uniformly anchored zirconocene complex on magnetic reduced graphene oxide (rGO@Fe3O4/ZrCp2Cl x (x = 0, 1, 2)) as a novel and reusable nanocatalyst for synthesis of N-arylacetamides and reductive-acetylation of nitroarenes

In this study, a crafted zirconocene complex on rGO@Fe3O4 as a novel magnetic nanocatalyst was synthesized and then characterized using FT-IR, SEM, EDX, VSM, ICP-OES, TGA, BET and MS analyses. Next, catalytic activity of the prepared nanocomposite rGO@Fe3O4/ZrCp2Cl x (x = 0, 1, 2) towards successful reduction of aromatic nitro compounds to arylamines using N2H4·H2O (80%) was investigated. The examined nanocatalyst also showed perfect catalytic activity for reductive-acetylation of aromatic nitro compounds to the corresponding N-arylacetamides without isolation of the prepared in situ amines using the N2H4·H2O/Ac2O system. Furthermore, acetylation of the commercially available arylamines to the corresponding N-arylacetamides was carried out by acetic anhydride in the presence of the rGO@Fe3O4/ZrCp2Cl x (x = 0, 1, 2) nanocomposite. All reactions were carried out in refluxing EtOH as a green solvent to afford the products in high yields. The obtained results exhibited that the nanocomposite of rGO@Fe3O4/ZrCp2Cl x (x = 0, 1, 2) showed a great catalytic activity in comparison to rGO and rGO@Fe3O4 as the parent constituents. Recovery and reusability of rGO@Fe3O4/ZrCp2Cl x (x = 0, 1, 2) were also examined for 8 consecutive cycles without significant loss of the catalytic activity. This establishes the sustainable anchoring of the zirconocene complex on the surface and mesopores of the rGO@Fe3O4 nanohybrid system.

Magnetically Directed Co-nanoinitiators for Cross-Linking Adhesives and Enhancing Mechanical Properties

Magnetically directed localized polymerization is of immense interest for its extensive impacts and applications in numerous fields. The use of means untethered from an external magnetic field to localize initiation of polymerization to develop a curing system is a novel concept, with a sustainable, efficient, and eco-friendly approach and a wide range of potential in both science and engineering. However, the conventional means for the initiation of polymerization cannot define the desirable location of polymerization, which is often exacerbated by the poor temporal control in the curing system. Herein, the copper-immobilized dendrimer-based magnetic iron oxide silica (MNPs-G2@Cu²⁺) co-nanoinitiators are rationally designed as initiators for redox radical polymerization. The nanoinitiators are magnetically responsive and therefore enable localized polymerization using an external magnetic field. In this work, anaerobic polymerization of an adhesive composed of triethylene glycol dimethacrylate, tert-butyl peroxybenzoate, and MNPs-G2@Cu²⁺ as the magnetic co-nanoinitiators has been investigated. The use of a magnet locates and promotes redox free radical polymerization through the synergistic functions between peroxide and MNPs-G2@Cu²⁺ co-nanoinitiators. The mechanical properties of the resulting polymer are considerably reinforced because the MNPs-G2@Cu²⁺ co-nanoinitiators concurrently play another crucial role as nanofillers. This strategy provides a novel approach for magnetically tunable localized polymerization, which allows new opportunities to govern the formulation of advanced adhesives through polymerization under hazard-free conditions for various promising applications.

Magnetically recyclable silica-coated ferrite magnetite-K10 montmorillonite nanocatalyst and its applications in O, N, and S-acylation reaction under solvent-free conditions

Novel silica-coated ferrite nanoparticles supported with montmorillonite (K₁₀) have been prepared successfully by using a simple impregnation method. Further, these nanoparticles were characterized by using different analytical methods like FT-IR, PXRD, EDS, and FE-SEM techniques. In addition, these nanoparticles have been explored for their catalytic activity for the O, N, and S-acylation reactions under solvent-free conditions which gave moderate to excellent yields in a much shorter reaction time. Moreover, these nanoparticles could easily be separated out from the reaction medium after the reaction completion by using an external magnetic field and have been re-used for 10 cycles without any significant loss of the catalytic activity.

Novel silica-coated ferrite nanoparticles supported with montmorillonite (K₁₀) have been prepared and explored for their catalytic activity for the O, N, and S-acylation reactions under solvent-free conditions.

Preparation of a magnetic and recyclable superparamagnetic silica support with a boronic acid group for immobilizing Pd catalysts and its applications in Suzuki reactions

A novel, high activity and magnetic nanoparticles (Fe3O4@SiO2-APBA-Pd) catalyst was prepared. It is 8–15 nm with 0.2–0.6 nm Pd particles. It can be reused 7 runs and catalyze 14 kinds of Suzuki reactions.

Adhesive functionalized ascorbic acid on CoFe2O4: a core–shell nanomagnetic heterostructure for the synthesis of aldoximes and amines

This paper reports on the simple synthesis of novel green magnetic nanoparticles (MNPs) with effective catalytic properties and reusability. These heterogeneous nanocatalysts were prepared by the anchoring of Co and V on the surface of CoFe₂O₄ nanoparticles coated with ascorbic acid (AA) as a green linker. The prepared nanocatalysts have been identified by scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray atomic mapping, thermogravimetric analysis, X-ray powder diffraction, vibrating sample magnetometer analysis, coupled plasma optical emission spectrometry and Fourier transform infrared spectroscopy. The impact of CoFe₂O₄@AA-M (Co, V) was carefully examined for NH₂OH·HCl oximation of aldehyde derivatives first and then for the reduction of diverse nitro compounds with sodium borohydride (NaBH₄) to the corresponding amines under green conditions. The catalytic efficiency of magnetic CoFe₂O₄@AA-M (Co, V) nanocatalysts was investigated in production of different aldoximes and amines with high turnover numbers (TON) and turnover frequencies (TOF) through oximation and reduction reactions respectively. Furthermore, the developed environment-friendly method offers a number of advantages such as high turnover frequency, mild reaction conditions, high activity, simple procedure, low cost and easy isolation of the products from the reaction mixture by an external magnetic field and the catalyst can be reused for several consecutive runs without any remarkable decrease in catalytic efficiency.

Heterogeneous catalysts were prepared by the anchoring of cobalt and vanadium on the surface of CoFe₂O₄ coated with ascorbic acid.

Recent Novel Hybrid Pd–Fe3O4 Nanoparticles as Catalysts for Various C–C Coupling Reactions

The use of nanostructure materials as heterogeneous catalysts in the synthesis of organic compounds have been receiving more attention in the rapid developing area of nanotechnology. In this review, we mainly focused on our own work on the synthesis of hybrid palladium–iron oxide nanoparticles. We discuss the synthesis of Pd–Fe3O4—both morphology-controlled synthesis of Pd–Fe3O4 and transition metal-loaded Pd–Fe3O4—as well as its application in various C–C coupling reactions. In the case of rose-like Pd–Fe3O4 hybrid nanoparticles, thermal decomposition can be used instead of oxidants or reductants, and morphology can be easily controlled. We have developed a method for the synthesis of nanoparticles that is facile and eco-friendly. The catalyst was recyclable for up to five continual cycles without significant loss of catalytic activity and may provide a great platform as a catalyst for other organic reactions in the near future.

Advances in Magnetic Nanoparticles-Supported Palladium Complexes for Coupling Reactions

Carbon‒carbon (C‒C) and carbon‒heteroatom (C‒X) bonds that form via transition-metal-catalyzed processes have been extensively used in the organic synthesis and preparation of natural products and important compounds such as heterocycles, biologically active molecules, and dendrimers. Among the most significant catalysts, magnetic nanoparticles-supported palladium complexes are very effective, versatile, and heterogeneous catalysts for a wide range of C‒C and C‒X coupling reactions due to their reusability, thermal stability, and excellent catalytic performance. In this review, recent advances to develop magnetic nanoparticles supported palladium complexes, including their preparation, characterization, catalytic application, and reusability in the formation of both C‒C and C‒X bonds, by authors such as Sonogashira, Heck, Suzuki‒Miyaura, and Stille, and a few examples concerning N-arylation, S-arylation, and Csp2-P coupling reactions are discussed.

Reusable magnetic PdxCoy nanoalloys confined in mesoporous carbons for green Suzuki–Miyaura reactions

(Pd_x–Co_y)@MC were prepared in one-pot via an eco-friendly route and used many times for Suzuki reactions in H₂O or H₂O/EtOH mixture.

Recyclable Pd/CuFe2O4 nanowires: a highly active catalyst for C–C couplings and synthesis of benzofuran derivatives

Pd/CuFe₂O₄ nanowire-catalyzed cross coupling transformations are described. Notably, these reactions showed excellent functional group tolerance. Further, the protocol is applied to a one-pot synthesis of benzofurans via a Sonogashira coupling and intramolecular etherification sequence. The catalyst was reused and found to maintain its activity and stability.

Efficient heterogeneous Pd/CuFe₂O₄ nanowires which catalyze cross coupling transformations are described. The protocol is applied to a one-pot synthesis of benzofurans via Sonogashira coupling and an intramolecular etherification sequence.

Sulfonated carbon-encapsulated iron nanoparticles as an efficient magnetic nanocatalyst for highly selective synthesis of benzimidazoles

Various benzimidazoles were obtained by applying sulfonated carbon-encapsulated iron nanoparticles as the nanocatalyst.

Development and Application of a Recyclable High-Load Magnetic Co/C Hybrid ROMP-Derived Benzenesulfonyl Chloride Reagent and Utility of Corresponding Analogues

The development and application of high-load, recyclable magnetic Co/C hybrid ROMP-derived benzenesulfonyl chloride and analogues is reported. The regeneration and utility of these reagents in the methylation/alkylation of various carboxylic acids is demonstrated via efficient retrieval of the magnetic reagent with a neodymium magnet. Additional reactions employing the analogue sulfonic acid and in situ generated magnetic benzenesulfonyl azide are also reported.

A convenient, efficient and reusable N-heterocyclic carbene-palladium(ii) based catalyst supported on magnetite for Suzuki–Miyaura and Mizoroki–Heck cross-coupling reactions

In the present work, a new magnetic nanoparticle supported N-heterocyclic carbene-palladium(ii) (NO₂-NHC-Pd@Fe₃O₄) nanomagnetic catalyst was synthesized by a facile multistep synthesis under aerobic conditions.

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.

An immobilized symmetrical bis-(NHC) palladium complex as a highly efficient and recyclable Suzuki–Miyaura catalyst in aerobic aqueous media

A novel palladium-silica complex was prepared and characterized. This complex is a highly efficient and easily recyclable catalyst for Suzuki–Miyaura cross-coupling reaction under mild aqueous conditions, and can be reused efficiently up to 6 consecutive runs.

Surface-Plasmon-Enhanced Photodriven CO2 Reduction Catalyzed by Metal-Organic-Framework-Derived Iron Nanoparticles Encapsulated by Ultrathin Carbon Layers

Highly efficient utilization of solar light with an excellent reduction capacity is achieved for plasmonic Fe@C nanostructures. By carbon layer coating, the optimized catalyst exhibits enhanced selectivity and stability applied to the solar-driven reduction of CO2 into CO. The surface-plasmon effect of iron particles is proposed to excite CO2 molecules, and thereby facilitates the final reaction activity.

CuO nanostructures of variable shapes as an efficient catalyst for [3 + 2] cycloaddition of azides with terminal alkyne

CuO nanowires exhibited highest catalytic efficiency for the cycloaddition reaction between azide and terminal alkyne, featuring short reaction time, soft reaction conditions and complete regioselectivity.

Synthesis of the first magnetic nanoparticles with a thiourea dioxide-based sulfonic acid tag: application in the one-pot synthesis of 1,1,3-tri(1H-indol-3-yl) alkanes under mild and green conditions

Synthesis of the first thiourea dioxide-based silica-coated Fe₃O₄magnetic nanoparticles as an exquisite, extraordinary and effective catalyst for the synthesis of 1,1,3-tri(1H-indol-3-yl) alkane derivatives.

Palladium(ii) tetrasulfophthalocyanine covalently immobilized on keratin protein grafted graphene oxide nanosheets as a new high-performance catalyst for C–C coupling reactions

Covalent immobilization of palladium(ii) tetrasulfophthalocyanine on keratin grafted graphene oxide nanosheets for catalytic application in C–C coupling reactions.

Pd nanoparticles synthesized in situ with the use of Euphorbia granulate leaf extract: Catalytic properties of the resulting particles

For the first time the extract of the plant of Euphorbia granulate was used to green synthesis of Pd nanoparticles (NPs) as a heterogeneous catalyst for the phosphine-free Suzuki-Miyaura coupling reaction at room temperature. This method is a facile and eco-friendly way in organic synthesis using the plant extract as biomedia, bioreductant and capping ligand which considerably stabilizes the surface of Pd NPs. The presence of flavonoid and phenolics acids in the extract could be responsible for the reduction of Pd(2+) ions and formation of the corresponding Pd NPs.

A novel magnetic NiFe2O4@graphene–Pd multifunctional nanocomposite for practical catalytic application

A novel NiFe₂O₄@GN–Pd was used as outstanding catalyst for the Suzuki reaction in EtOH/H₂O. The hybrid catalyst could be recycled and reused with the simple application of an external magnetic field, while keeping similar catalytic activity for six successive reactions.

Halide inhibition of the copper-catalysed azide–alkyne cycloaddition

Halides are inhibitors of the copper-catalysed azide–alkyne cycloaddition. Case studies in this inhibition are presented, along with experimental measures useful in accommodating halides in this widely used reaction.

Immobilized Pd on magnetic nanoparticles bearing proline as a highly efficient and retrievable Suzuki–Miyaura catalyst in aqueous media

Immobilized Pd on magnetic nanoparticles bearing proline as a highly efficient and retrievable Suzuki–Miyaura catalyst in aqueous media.

Magnetic-graphitic-nanocapsule templated diacetylene assembly and photopolymerization for sensing and multicoded anti-counterfeiting

Molecular self-assembly, a process to design molecular entities to aggregate into desired structures, represents a promising bottom-up route towards precise construction of functional systems. Here we report a multifunctional, self-assembled system based on magnetic-graphitic-nanocapsule (MGN) templated diacetylene assembly and photopolymerization. The as-prepared assembly system maintains the unique color and fluorescence change properties of the polydiacetylene (PDA) polymers, while also pursues the superior Raman, NIR, magnetic and superconducting properties from the MGN template. Based on both fluorescence and magnetic resonance imaging (MRI) T2 relaxivity, the MGN@PDA system could efficiently monitor the pH variations which could be used as a pH sensor. The MGN@PDA system further demonstrates potential as unique ink for anti-counterfeiting applications. Reversible color change, strong and unique Raman scattering and fluorescence emission, sensitive NIR thermal response, and distinctive magnetic properties afford this assembly system with multicoded anti-counterfeiting capabilities.