Shape-dependent catalytic activity of Fe₃O₄ nanostructures under the influence of an external magnetic field for multicomponent reactions in aqueous media

Abstract

High-quality and high-active one-dimensional (1-D) Fe3O4 nanostructure was synthesized via the external magnetic field (EMF) at intensity range 0-526 µT in aqueous solution, without using any surfactant and organic solvent at room temperature. Characterization of the products were carried out using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectrophotometry (FT-IR), laser particle size analyzer, surface area (Brunauer-Emmett-Teller, BET), and vibrating sample magnetometer (VSM). The results show that EMF at a critical adjusted intensity has a great influence on the structural features such as the morphology, particle size, surface pores size distribution, and magnetic properties of the Fe3O4 nanostructure. The morphology changed from peg-like network structures to needle-like cage structures by exposure synthesis treatment with EMF at intensity 362 µT. The catalytic activity of two nanostructures prepared in the presence and absence of EMF were compared in tricomponents reaction (TCR) for the synthesis of trisubstituted imidazoles under electromagnetic irradiation. The best results were obtained for the catalyst produced in the presence of EMF while the tricomponent reaction carried out in the absence of EMF. This EMF conditions was used for preparation of a series of alkyl-, aryl-, and heteroaryl-substituted imidazoles from the corresponding benzoin and benzil in aqueous solution as green reaction conditions. It was found that the catalyst can be efficiently recycled and reused for several repeating cycles without significant loss of catalytic activity.

Study on the HPA immobilisation on Al-SBA-15 support over Brønsted groups

“…Recently, immobilising HPA on other solid supports has been demonstrated to be very promising to address this issue. Numerous types of supports including silica [2][3][4][5][6][7][8][9][10][11][12][13], titania [14][15][16], zeolites (Y, USY) [17][18][19], mesoporous materials (SBA-15, MCM-41) [20][21][22][23], carbon [24][25][26] and graphene oxide [27] have been used to immobilise HPA by encapsulation, tethering and grafting routes. For example, Mukai et.…”

Magnetic biosensors for identification of SARS-CoV-2, Influenza, HIV, and Ebola viruses: a review

“…One of the critical strategies to protect MMs from oxidation and corrosion is the functionalization their surfaces by polymers, metals, and biomolecule agents. Therefore, the functionalized-MMs in various forms of oxides (Fe [91] chemical and biological template-directed [92] micro-emulsion [93] thermal decomposition/deposition [94] hydrothermal/solvothermal [95] magnetic field [96][97][98] sonochemical [99] microwave [100,101] spray self-assembly [102] pyrolysis [103] laser-induced [104] bacteria-assisted [105] algae-assisted [106] plant parts [107] electrospinning [108,109] etc. Table 1 have been listed some the detection mechanism of these MMs-based biosensors to detect biological molecules in recent years.…”

Synthesis of benzoin under supramolecular catalysis involving cyclodextrins in water: application for the preparation of the antiepileptic drug phenytoin

“…In recent years, vitamin B 1 (VB 1 ) was reported as a new catalyst for benzoin condensation reaction. [12][13][14][15][16][17][18][19] However, the reaction system needs organic solvents (ethanol) and is carried out under reux conditions. An interesting strategy is that the conjugates of VB 1 with CDs, where VB 1 is covalently linked to CDs, catalyzed the benzoin condensation reaction, which required DMSO as a solvent.…”