Fe3O4@C@MCM41-guanidine core-shell nanostructures as a powerful and recyclable nanocatalyst with high performance for synthesis of Knoevenagel reaction

In this study, preparation, characterization and catalytic application of a novel core-shell structured magnetic with carbon and mesoporous silica shells supported guanidine (Fe₃O₄@C@MCM41-guanidine) are developed. The Fe₃O₄@C@MCM41-guanidine was prepared via surfactant directed hydrolysis and condensation of tetraethyl orthosilicate around Fe₃O₄@C NPs followed by treatment with guanidinium chloride. This nanocomposite was characterized by using Fourier transform infrared spectroscopy, vibrating sample magnetometry, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, thermal gravimetric analysis, wide-angle X-ray diffraction and low-angle X-ray diffraction techniques. This nanocomposite have high thermal, chemical stability, and uniform size. Fe₃O₄@C@MCM41-guanidine catalyst demonstrated high yield (91-98%) to prepare of Knoevenagel derivatives under the solvent free conditions at room temperature in the shortest time. Also, this catalyst was recovered and reused 10 times without significant decrease in efficiency and stability. Fortunately, an excellent level of yield (98-82%) was observed in the 10 consecutive catalyst cycles.

Yolk-shell structured magnetic mesoporous silica: a novel and highly efficient adsorbent for removal of methylene blue

In this study, a novel magnetic mesoporous silica with yolk-shell structure (Fe3O4@Void@m.SiO2) was successfully synthesized via a polymer-template assisted method. The Fe3O4@Void@m.SiO2 was characterized by using FT-IR, EDS, SEM, TEM, VSM, PXRD and nitrogen adsorption-desorption analyses. The Fe3O4@Void@m.SiO2 nanocomposite showed high efficiency in adsorption of an organic dye and water pollutant called methylene blue (MB) with 98.2% removal capability. Furthermore, the effect of different parameters in the adsorption of MB was investigated. Different models of kinetic were examined and compared with each other. The recoverability and reusability of designed Fe3O4@Void@m.SiO2 material were also studied under applied conditions.

Ag2CO3 containing magnetic nanocomposite as a powerful and recoverable catalyst for Knoevenagel condensation

In this paper, the synthesis, characterization and catalytic application of a novel magnetic silica-supported Ag2CO3 (MS/Ag2CO3) with core-shell structure are developed. The MS/Ag2CO3 nanocomposite was prepared through chemical modification of magnetic MS nanoparticles with AgNO3 under alkaline conditions. The structure, chemical composition and magnetic properties of MS/Ag2CO3 were investigated by using VSM, PXRD, FT-IR, EDX and SEM techniques. The MS/Ag2CO3 nanocomposite was used as an effective catalyst for the Knoevenagel condensation under solvent-free conditions at 60 °C in an ultrasonic bath. The recovery and leaching tests were performed to study the nature of the MS/Ag2CO3 catalyst under applied conditions.

Development of New Thiazole Complexes as Powerful Catalysts for Synthesis of Pyrazole-4-Carbonitrile Derivatives under Ultrasonic Irradiation Condition Supported by DFT Studies

In this study, we are interested in preparing Fe(III), Pd(II), and Cu(II) complexes from new thiazole derivatives. All syntheses were elaborately elucidated to estimate their molecular and structural formulae, which agreed with those of mononuclear complexes. The square-planer geometry of Pd(II) complex (MATYPd) was the starting point for its use as a heterocatalyst in preparing pyrazole-4-carbonitrile derivatives 4a-o using ultrasonic irradiation through a facile one-pot reaction. The simple operation, short-time reaction (20 min), and high efficiency (97%) were the special advantages of this protocol. Furthermore, this green synthesis strategy was advanced by examination of the reusability of the catalyst in four consecutive cycles without significant loss of catalytic activity. The new synthesis strategy presented remarkable advantages in terms of safety, simplicity, stability, mild conditions, short reaction time, excellent yields, and use of a H₂O solvent. This catalytic protocol was confirmed by the density functional theory (DFT) study, which reflected the specific characteristics of such a complex. Logical mechanisms have been suggested for the successfully exerted essential physical parameters that confirmed the superiority of the Pd(II) complex in the catalytic role. Optical band gap, electrophilicity, and electronegativity features, which are essential parameters for the catalytic behavior of the Pd(II) complex, are based mainly on the unsaturated valence shell of Pd(II).

Core–shell structured magnetic mesoporous silica supported Schiff-base/Pd: an efficacious and reusable nanocatalyst

Preparation, characterization and catalytic application of a novel magnetic ordered mesoporous silica supported Schiff-base/Pd (Fe₃O₄@MCM-41-SB/Pd) are developed.

Core–shell structured magnetic silica supported propylamine/molybdate complexes: an efficient and magnetically recoverable nanocatalyst

A novel core–shell structured magnetic silica supported propylamine/molybdate complex (Fe₃O₄@SiO₂/Pr-NMo[Mo₅O₁₈]) is prepared, characterized and applied as an effective and easily recoverable nanocatalyst in the synthesis of pyrano-pyrazole derivatives.