Synthesis and characterization of Fe3O4@SiO2–polymer-imid–Pd magnetic porous nanospheres and their application as a novel recyclable catalyst for Sonogashira–Hagihara coupling reactions

We demonstrate herein the modification of magnetic nanoparticles and their use as a magnetic nanocatalyst in direct coupling reactions of aryl halides with terminal alkynes. Magnetite particles were prepared by simple co-precipitation method in aqueous medium, and then Fe₃O₄@ SiO₂ nanosphere was synthesized by using nano-Fe₃O₄ as the core, TEOS as the silica source and PVA as the surfactant. Fe₃O₄@SiO₂ was coated with polymeric N-heterocyclic carbene/Pd. The samples were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, field emission scanning electron microscopy, dynamic light scattering, thermogravimetric analysis, vibration sample magnetometer and N₂ adsorption–desorption isotherm analysis. Poly (N-vinyl imidazole) functionalized Fe₃O₄@SiO₂ nanoparticle was found to be an efficient nanocatalyst in Sonogashira–Hagihara cross-coupling reactions. The nanocatalyst can be easily recovered by a magnetic field and reused for six runs without appreciable loss of its catalytic activity.     

Synthesis and characterization of magnetic dichromate hybrid nanomaterials with triphenylphosphine surface modified iron oxide nanoparticles (Fe3O4@SiO2@PPh3@Cr2O72−)

In this study, a new magnetic hybrid nanomaterials Fe₃O₄@SiO₂@PPh₃@Cr₂O₇²⁻ is introduced. First, the magnetic Fe₃O₄ nanoparticles have been synthesized by co-precipitation method. Then, tetraethyl orthosilicate has been used for production of core–shell nanoparticles Fe₃O₄@SiO₂. The core–shell magnetic nanoparticles system Fe₃O₄@SiO₂ functionalization was synthesized using (3-chloropropyl) trimethoxysilane and triphenylphosphine and the cationic part was prepared for immobilization of anionic part of the Cr (VI) catalysts including Cr₂O₇²⁻. After immobilization of the catalyst, its structure was detected by using Fourier transform infrared (FT-IR), solid state UV–Vis, elemental analysis, X-ray fluorescence (XRF), X-ray diffraction (XRD) and the particle size and morphology were elaborated by scanning electron microscope (SEM) and XRD. Magnetism properties were quantified by vibrating sample magnetometer (VSM).     

β-Cyclodextrin derivatives hybrid Fe3O4 magnetic nanoparticles as the drug delivery for ketoprofen

β-Cyclodextrin (β-CD) and its derivatives carboxymethyl-β-CD (CM-β-CD) and 2,6-dimethyl-β-CD (DM-β-CD) modified magnetic nanoparticles (CD-MNPs) were synthesized via layer-by-layer method. CDs grafted onto Fe₃O₄ MNPs were demonstrated by transmission electron microscopy, Fourier transform infrared and Zeta potential. Magnetic properties of CM-β-CD-MNPs, DM-β-CD-MNPs and β-CD-MNPs were characterized by vibrating sample magnetometer and the magnetic saturation values were 47, 46 and 44 emu g^?1, respectively. CD-MNPs as drug carriers were investigated by inclusion behavior and in vitro release using ketoprofen (KP) as a model drug. The maximum adsorption quantities of CM-β-CD-MNPs, DM-β-CD-MNPs and β-CD-MNPs for KP were 37.03, 7.63 and 25.12 mg g^?1, respectively, and the loading behaviors followed the Langmuir adsorption isotherm model with monolayer adsorption. The release profiles of KP released from KP-loaded CD-MNPs were rapid in initial 60 min and then gradually tend to level off, the release efficiency order was CM-β-CD-MNPs > β-CD-MNPs > DM-β-CD-MNPs, which was consistent with the order of inclusion capability. Therefore, the CD-MNPs were promising candidates for drug delivery.     

Synthesis and Characterization of Novel Magnetic Poly(urethane-imide)/Fe3O4@SiO2–NH2 Nanocomposites

Russian Journal of Applied Chemistry - Poly(urethane-imide)/Fe3O4@SiO2–NH2 nanocomposites were synthesized by the reaction of 4,4′-diphenylmethane diisocyanate (MDI), polypropylene...     

Preparation and characterization of SO4 2−/Fe2O3–TiO2–Nd2O3 catalyst

This paper reports on the preparation of SO₄ ^2?/Fe₂O₃–TiO₂–Nd₂O₃ (SFTN) by combustion method. The effect of Nd content on catalytic activity was investigated. The prepared materials doped and undoped by Nd were compared by means of TG-DTG, XRD, FT-IR, NH₃-TPD and TEM techniques. Results indicated that the introduction of Nd improved the catalytic activities of the catalysts. Catalytic activity of SFTN was the highest with 98.3 % menthol conversion when Nd content was at 2 wt%. The introduction of Nd stabilized the coordination bond between the sulfate irons and the metallic oxides, helping in the formation of solid acid sites, enhancing the dispersion of catalyst particles, and inhibiting the growth of catalyst particles under heating.     

Synthesis and characterization of nanocrystalline α-Al2O3 using Al and Fe2O3 (hematite) through mechanical alloying

In this present work, the synthesis of nanocrystalline α-Al₂O₃ using pure aluminum (Al) and Fe₂O₃ (hematite) as the precursors by mechanical alloying technique has been studied. The formation of α-Al₂O₃ nanocrystallites occurs during the solid-state reaction and through the reduction treatment. Also in this paper, effects of milling time on particle size and the lattice strain nanocrystalline α-Al₂O₃ have been investigated. Obtained powders were evaluated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), differential thermal analysis (DTA), thermal gravimetric analysis (TGA) and X-ray diffraction (XRD). The obtained results indicated that a reduction reaction was completed after 2 h milling in a planetary mill. The crystallite size of obtained α-alumina (α-Al₂O₃) was in general about 12 nm. Finally, the results showed appropriate homogeneity and dispersion of related nanocrystalline.     

Synthesis of carboxymethyl β-cyclodextrin bonded Fe3O4@SiO2–NH2 core-shell magnetic nanocomposite adsorbent for effective removal of Pb(II) from wastewater

Journal of Sol-Gel Science and Technology - In this work, a novel functionalized magnetic Fe3O4@SiO2 core-shell nanoparticles grafted with carboxymethyl β-cyclodextrin (CM-β-CD) is...     

Fe3O4@SiO2-polymer-imid-Pd magnetic porous nanosphere as magnetically separable catalyst for Mizoroki–Heck and Suzuki–Miyaura coupling reactions

The activity of palladium nanoparticles supported on poly (N-vinylpyrrolidone) grafted Fe₃O₄@SiO₂ was investigated in the cross-coupling reactions. We have applied this catalyst under low loading of the supported palladium nanoparticles for the coupling of aryl halides with alkenes (Mizoroki–Heck reaction) and organoboronic acids (Suzuki–Miyaura reaction) in the absence of phosphorous ligands. Short reaction times and excellent yields of the products express the effectiveness of this catalyst. The nanocatalyst can be separated from the reaction mixture by applying a permanent magnet externally and can be reused for six times without appreciable change in catalytic activity. Also, the amount of leaching of Pd nanoparticles has been determined by ICP analysis and results showed low leaching of the metal into solution from the supported catalyst.     

High adsorptive γ-AlOOH(boehmite)@SiO2/Fe3O4 porous magnetic microspheres for detection of toxic metal ions in drinking water

γ-AlOOH(boehmite)@SiO(2)/Fe(3)O(4) porous magnetic microspheres with high adsorption capacity toward heavy metal ions were found to be useful for the simultaneous and selective electrochemical detection of five metal ions, such as ultratrace zinc(II), cadmium(II), lead(II), copper(II), and mercury(II), in drinking water.     

Synthesis,characterization and magnetic properties of γ-Fe2O3 nanoparticles via a non-aqueous medium

Acicular shaped γ-Fe₂O₃ nanoparticles (major axis: 17±2 nm; minor axis: 1.7±1 nm) have been prepared using lauric acid as a non-aqueous medium. The products were investigated by IR, TG-DTA, XRD, Raman, SEM, TEM and magnetization measurements. For the preparation of pure γ-Fe₂O₃ nanoparticles, the suitable condition of the molar ratio of lauric acid to iron nitrate is set 2:1 and the appropriate temperature lies in the range 573–673 K. Besides, either pure α-Fe₂O₃ or a mixture of γ-Fe₂O₃ and α-Fe₂O₃ can also be obtained with the change of the molar ratio of lauric acid to iron nitrate. The experimental results indicate that the particle sizes, thermal stability and magnetic properties of the iron oxide strongly depend on the conditions in the preparation.     

Fe3O4@SiO2@Propyl–ANDSA: as a new catalyst for one-pot synthesis of 4H-chromene

Research on Chemical Intermediates - This work describes a new method for a one-pot multicomponent condensation of a variety of aldehydes with dimedone and malononitrile in water, providing a...     

Synthesis and characterization of a novel Fe3O4@SiO2/bipyridinium dichloride nanocomposite and its application as a magnetic and recyclable phase-transfer catalyst in the preparation of β-azidoalcohols, β-cyanohydrins,and β-acetoxy alcohols

β-Azidoalcohols, β-cyanohydrins, and β-acetoxy alcohols have been synthesized in the presence of a Fe₃O₄@SiO₂/bipyridinium nanocomposite (Fe₃O₄@SiO₂/BNC) as a novel magnetic and recyclable phase-transfer catalyst (PTC) in water. The catalyst was characterized with FT–IR, SEM, XRD, VSM, and TGA. This methodology offers several advantages, including easy work-up procedure, excellent regioselectivity, high yields, short reaction times, recyclable catalyst, easy separation of the catalyst through an external magnet and eco-friendly procedure.     

Synthesis and characterization of chitosan–polyvinylpyrrolidone–bovine serum albumin-coated magnetic iron oxide nanoparticles as potential carrier for delivery of tamoxifen

The proposed study examined the preparation of chitosan (CS)–polyvinylpyrrolidone (PVP)–bovine serum albumin (BSA)-coated magnetic iron oxide (Fe₃O₄) nanoparticles (Fe₃O₄–CS–PVP–BSA) to use as potential drug delivery carriers for delivery of tamoxifen drug (TAM) . The anticancer drug selected in this study was tamoxifen which can be used for the human breast cancer treatment. These prepared nanoparticles were characterized by FTIR, XRD, SEM, AFM, TEM, CD and VSM techniques. The swelling studies have been measured at different (10, 20, 30, 40, 50%) drug loading. The mean particle size of the tamoxifen-loaded nanoparticles system (Fe₃O₄–CS–TAM, Fe₃O₄–CS–TAM–PVP and Fe₃O₄–CS–TAM–PVP–BSA) as measured by Malvern Zetasizer ranged between 350 ± 2.3 and 601 ± 1.7 nm. As well as these drug-loaded nanoparticles were positively charged. The zeta potential was in the range of 28.9 ± 3.5 and 50.8 ± 3.9 mV. The encapsulation efficiency was between 63.60 ± 2.11 and 96.45 ± 2.12%. Furthermore, in vitro release and drug loading efficiency from the nanoparticles were investigated. The cytotoxicity of prepared nanoparticles was verified by MTT assay. In vitro release studies were executed in 4.0 and 7.4 pH media to simulate the intestinal and gastric conditions and different temperature (37 and 42 °C). Hence, the prepared tamoxifen-loaded nanoparticles system (Fe₃O₄–CS–TAM, Fe₃O₄–CS–TAM–PVP and Fe₃O₄–CS–TAM–PVP–BSA) could be a promising candidate in cancer therapy.     

Synthesis and characterization of Na2O–CaO–SiO2 glass–ceramic

The Na₂O–CaO–SiO₂ ternary glass–ceramic with the composition of 49 mass% Na₂O, 20 mass% CaO, and 31 mass% SiO₂ was prepared by the conventional method. The ternary glass–ceramic was characterized using X-ray diffraction (XRD), differential thermal analysis (DTA), thermogravimetric analysis, Fourier transform infrared spectroscopy, and scanning electron microscopy techniques. The Na₂CaSiO₄ phase, having the cubic crystal system, with the crystallite size of 25.14 nm and lattice parameter of 0.7506 nm was determined from the XRD pattern. The activation energy of the glass–ceramic calculated from the DTA curves was found to be 162.02 kJ mol^?1. The Avrami exponent was found to be ~2 indicating a one-dimensional growth process. The mass loss percent from ambient temperature to 1,173 K is less than 1 %. The density was calculated to be 2,723 kg m^?3. The fine-grained microstructure with the particle sizes less than 1 μm was confirmed by the scanning electron microscope micrograph.     

L-Tyrosine-Pd complex supported on Fe3O4 magnetic nanoparticles: A new catalyst for C–C coupling and Synthesis of sulfides

In the present work, Fe₃O₄@L-Tyrosine-Pd heterogeneous nanocatalyst was prepared by a simple and inexpensive procedure. The prepared nanocatalyst was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray Diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), inductively coupled plasma optical emission spectroscopy (ICP-OES), scanning electron microscopy (SEM), Transmission electron microscopy)TEM(, X-ray mapping, thermal gravimetric analysis (TGA), N₂ adsorption and desorption (BET) and vibrating sample magnetometer (VSM) techniques. Besides, it was employed as an efficent catalyst for C-C cross coupling and S-arylation reactions under green conditions. The optimized conditions for these reactions are described. The heterogeneous catalyst can be easily separated by applying a simple magnet and can also be reused in several consecutive runs without appreciable change in its catalytic activity.     

Optical and magnetic properties of small-size core–shell Fe3O4@C nanoparticles

Core–shell Fe₃O₄@C magnetic nanoparticles which are of great interest for research have a widely applied prospect. However, people know little about the optical and magnetic properties of the small-size Fe₃O₄@C nanoparticles due to the difficulty of uniformly coating small size Fe₃O₄ nanoparticles. In this paper, the influence of carbon shell coating on the optical and magnetic properties of small size Fe₃O₄ nanoparticles was presented. Carbon coating can strengthen the absorption intensity in the UV–visible light region through the introduction of oxygen defects on the surface of the nanoparticles by nitric acid treatment. Fe₃O₄ and Fe₃O₄@C nanoparticles both display typical superparamagnetic behavior in the high-temperature regime and a blocked state at low temperature from hysteresis loop, zero-field cooled and field cooled curves. Carbon coating reduce the surface uniaxial anisotropy, thus the average blocking temperature <T_B> decreases from 59 K of Fe₃O₄ nanoparticles to 50 K of Fe₃O₄@C nanoparticles.     

Magnetic infrared responsive photocatalyst: fabrication,characterization, and photocatalytic performance of β-NaYF4:Yb3+,Tm3+/TiO2/Fe3O4@SiO2 composite

Research on Chemical Intermediates - To enhance photocatalytic activity spectra area of the TiO2 based photocatalyst, and to separate and recycle photocatalyst easily, magnetic photocatalyst was...