A novel core@double-shell three-layer structure with dendritic fibrous morphology based on Fe3O4@TEA@Ni-organic framework: a highly efficient magnetic catalyst in the microwave-assisted Sonogashira coupling reaction.

In synthetic organic chemistry, the formation of carbon-carbon bonds is a significant and substantial reaction. As a result, developing a highly active magnetic heterogeneous catalyst with excellent performance is a very appealing technique for constructing C-C bonds in organic chemistry. The present study describes the fabrication of a novel and readily recoverable nickel-based metal-organic framework (MOF) for C-C bond formation through the Sonogashira coupling reaction. The efficient magnetic core-shell structure (Fe3O4@TEA@MOF) with a 3D dendritic fibrous morphology was successfully synthesized using a hydrothermal approach by immobilizing Ni-based MOF onto the Fe3O4@TEA core-shell structure. The fabrication of Fe3O4@TEA@MOF was confirmed by various analyses; Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray analysis (EDS), and elemental mapping confirmed the stepwise fabrication of catalyst. X-ray diffraction analysis (XRD) showed the crystalline nature of the catalyst. Field-emission scanning electron microscopy (FE-SEM) displayed the 3D dendritic fibrous morphology. Thermogravimetric analysis (TGA) and vibrating sample magnetometer analysis (VSM) showed the excellent thermal stability and magnetic properties of Fe3O4@TEA@MOF. The Brunauer-Emmett-Teller analysis (BET) found that the fabricated catalyst with a surface area of 36.2 m2 g-1, pore volume of 0.18 cm3 g-1, and mean pore diameter of 20.38 nm belongs to mesoporous structures. In addition, the information from the inductively coupled plasma-optical emission spectroscopy (ICP-OES) about fresh and reused catalysts showed that the metal leaching amount is slight and about 1.98%. Other advantages of the Fe3O4@TEA@MOF catalyst can be mentioned as easily reusable for four runs and high performance (above 98%) in synthesizing diphenylacetylene from phenylacetylene, aryl halide, and cesium carbonate (as the base) under solvent-free and microwave conditions.

The Fe3O4@apple seed starch core-shell structure decorated In(III): A green biocatalyst for the one-pot multicomponent synthesis of pyrazole-fused isocoumarins derivatives under solvent-free conditions.

In current decades, the fabrication and design of magnetic biocatalysts have been advancing as green catalysts. Hence, in this paper, we use the apple seed starch to create indium(III) immobilized on Fe3O4@apple seed starch core-shell magnetic nanocatalyst (Fe3O4@apple seed starch-In(III)). The prepared catalyst was identified and evaluated with several analysis techniques. The application of this catalyst in the synthesis of isochromeno[4,3-c]pyrazole-5(1H)-one derivates under solvent-free conditions was a new approach with high efficiency. Due to the magnetic nature of the catalyst, the catalyst separation from the reaction medium is easy, and it is reusable for five runs without significant change in catalytic activity. The fabrication of this catalyst is based on green chemistry principles and is more economical and stable than other catalysts in the synthesis of pyrazole-fused isocoumarins heterocyclic compounds.

Synthesis of new chitosan Schiff base and its Fe2O3 nanocomposite: Evaluation of methyl orange removal and antibacterial activity.

New chitosan Schiff base (3EtO-4OH/Chit) and its 3EtO-4OH/Chit/Fe2O3 nanocomposite were synthesized and characterized by FTIR, 1H NMR, XRD, TGA, DSC and SEM. The result confirmed the preparation of 3EtO-4OH/Chit and its 3EtO-4OH/Chit/Fe2O3 nanocomposite. The efficiency of the prepared catalysts was studied for the methyl orange (MO) removal from aqueous solution. The effect of adsorbent dose and contact time on the removal of dye has been studied. Their antibacterial activities were considered against two Gram positive (S. aureus and B. cereus) and two Gram negative (E. coli and P. aeruginosa) bacteria and the results showed that the activity of the 3EtO-4OH/Chit/Fe2O3 is excellent and is more than chitosan and 3EtO-4OH/Chit. Thermogravimetry studies shows that the weight loss stages and the residual value at 600 °C are different for the two compounds. DSC curve of the title compounds 3EtO-4OH/Chit and 3EtO-4OH/Chit/Fe2O3 is different from each other. The reason for this difference could be due to the presence of iron oxide nanoparticles in 3EtO-4OH/Chit/Fe2O3.

Anchoring of triethanolamine-Cu(II) complex on magnetic carbon nanotube as a promising recyclable catalyst for the synthesis of 5-substituted 1H-tetrazoles from aldehydes.

The development of heterogenization of copper nanoparticles on conductive supports is very challenging and has received much attention. Here, we synthesize a practical, efficient, and inexpensive heterogeneous catalyst to grow stable metallic copper(II) nanoparticles on the surface of magnetic carbon nanotube (Fe3O4-CNT) catalyst support physically functionalized with triethanolamine (TEA) that acts as a low-cost and non-toxic ligand to capture the copper nanoparticles [Fe3O4-CNT-TEA-Cu(II)]. The as-prepared heterogeneous catalyst was characterized by different techniques, such as Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, thermogravimetric analysis, vibrating sample magnetometer, X-ray diffraction patterns, field-emission scanning electron microscopy, and atomic absorption spectroscopy analysis. The catalytic behavior of Fe3O4-CNT-TEA-Cu(II) was investigated in the preparation of 5-substituted 1H-tetrazole derivatives via one-pot, three-component reaction between aromatic aldehydes, hydroxylamine, and sodium azide. The low catalyst loading, wide substrate scope, use of inexpensive materials, simple separation of the catalyst from the reaction mixture by an external magnet, short reaction times, easy workup, affordability, and superb yield are some advantages of this protocol.

Polythiophene-functionalized magnetic carbon nanotube-supported copper(I) complex: a novel and retrievable heterogeneous catalyst for the "Phosphine- and Palladium-Free" Suzuki-Miyaura cross-coupling reaction.

A simple preparation of catalysts with high catalytic activity and superior cycling stability is very desirable. In this contribution, magnetic carbon nanotube functionalized by polythiophene (CNT-Fe3O4-PTh) acts as an efficient and retrievable host for copper nanoparticles to prepare CNT-Fe3O4-PTh-Cu(I) as a nontoxic and inexpensive catalyst. FT-IR, TGA, EDX, VSM, XRD, FE-SEM, TEM, and AAS techniques were employed to characterize the structure of the synthesized magnetic heterogeneous nanocomposite. Thereafter, the catalytic application of the catalyst was evaluated for the phosphine- and palladium-free Suzuki-Miyaura cross-coupling reaction in water/ethanol as a green media in short reaction times with good to excellent yields. Various derivatives of biaryl compounds were synthesized by reaction of aryl halides and phenylboronic acid. Simple methodology and easy workup, short reaction times, elimination of volatile and toxic solvents, biocompatible reaction conditions, and high yields are some advantages of this protocol. Moreover, the catalyst showed a good reusability owing to its magnetic properties and was recycled several times without appreciable decrease in its catalytic efficiency. Copper(I) nanoparticles supported on magnetic carbon nanotube functionalized by polythiophene (CNT-Fe3O4-PTh-Cu(I)), was prepared and used for ligand- and palladiumfree Suzuki-Miyaura cross-coupling reaction in water/ethanol as a green media in short reaction times with good to excellent yields. Reusability and stability tests demonstrated that the as prepared catalyst can be recycled with a negligible loss of its activity.

Hantzsch reaction on free nano-Fe2O3 catalyst: excellent reactivity combined with facile catalyst recovery and recyclability.

A magnetic nanoparticle catalyst was readily prepared from inexpensive starting materials which catalyzed the Hantzsch reaction. High catalytic activity and ease of recovery from the reaction mixture using an external magnet, and several reuse times without significant losses in performance are additional eco-friendly attributes of this catalytic system.