Fe3O4@SiO2/Schiff base complex of metal ions as an efficient and recyclable nanocatalyst for the green synthesis of quinoxaline derivatives

Fe₃O₄@SiO₂/Schiff base complex of metal ions catalyzed the reaction between phenylene-1,2-diamines and 1,2-diketones to produce quinoxalines in aqueous media at room temperature. This eco-friendly method provides several advantages such as mild reaction conditions, good to excellent yields, simple work-up, and nanocatalyst stability. Also, nanocatalyst can be simply recovered by a magnetic field and reused for at least five successive reactions.     

Cu(II) Schiff base complex supported on Fe3O4 nanoparticles as an efficient nanocatalyst for the selective aerobic oxidation of alcohols

Herein, we have prepared a new Cu(II) Schiff base complex supported onto the surface of modified Fe₃O₄ nanoparticles as highly stable, heterogeneous and magnetically recyclable nanocatalyst for the selective aerobic oxidation of different alcohols. The structure, morphology, chemical composition and magnetic property of the nanocatalyst and its precursors were characterized using FT‐IR, TGA, AAS, ICP‐AES, XRD, SEM, EDS, VSM and N₂ adsorption–desorption analyses. Characterization results exhibited the uniform spherical morphology for nanocatalyst and its precursors. A promising eco‐friendly method with short reaction time and high conversion and selectivity for oxidation of various primary and secondary alcohols under O₂ atmosphere condition was achieved. The synthesized nanocatalyst could be recovered easily by applying an external magnetic field and reused for least eight subsequent reaction cycles with only negligible deterioration in catalytic performance.     

Green synthesis of 1H-pyrazolo[1,2-b]phthalazine-2-carbonitrile derivatives using a new bifunctional base–ionic liquid hybrid magnetic nanocatalyst

The ionic liquid-base N,N,2,2,6,6-hexamethyl-N-(3-(trimethoxysilyl)propyl)piperidin-4-amonium iodide was grafted onto titana-coated NiFe₂O₄ nanoparticles for obtaining an efficient and reusable ionic liquid-base hybrid nanocatalyst. The structure of hybrid nanoparticles was characterized using FT-IR (Fourier-transform infrared spectroscopy), field emission scanning electron microscopy, EDS (energy-dispersive X-ray spectroscopy), EDS map scan, Brunauer–Emmett–Teller surface area analysis, CHN (elemental analysis), vibrating sample magnetometer and thermogravimetric analysis techniques. Furthermore, this novel hybrid catalyst was used in one-pot three-component synthesis of 3-amino-1-aryl-5,10-dioxo-1H-pyrazolo[1,2-b]phthalazine-2-carbonitrile derivatives under green and environmentally benign conditions. This protocol avoids the use of harmful catalysts, toxic solvents and harsh reaction conditions. The products were synthesized in excellent yields within short reaction time and identified using elemental analysis, FT-IR, ¹H NMR and ¹³C NMR spectroscopies.     

Polystyrene@graphene oxide-Fe3O4 as a novel and magnetically recyclable nanocatalyst for the efficient multi-component synthesis of spiro indene derivatives

Research on Chemical Intermediates - Polystyrene (PS)-coated magnetic graphene oxide (GO-Fe3O4) nanocomposite has been prepared and characterized by FT-IR, TEM and VSM techniques, and its catalytic...     

Magnetic Fe3O4-supported sulfonic acid-functionalized graphene oxide (Fe3O4@GO-naphthalene-SO3H): a novel and recyclable nanocatalyst for green one-pot synthesis of 5-oxo-dihydropyrano[3,2-c]chromenes and 2-amino-3-cyano-1,4,5,6-tetrahydropyrano[3,2-c]quinolin-5-ones

Research on Chemical Intermediates - Synthesis of a novel magnetic 1-naphthalenesulfonic acid-grafted graphene oxide (Fe3O4-GO-naphthalene-SO3H) via a three-step procedure has been described. The...     

Heterogenization of a molybdenum Schiff base complex as a magnetic nanocatalyst: An eco-friendly,efficient, selective and recyclable nanocatalyst for the oxidation of alkenes

A Schiff base ligand derived from 5-bromo-2-hydroxybenzaldehyde and 2,2′-dimethylpropylenediamine (H₂L) and its corresponding dioxomolybdenum(VI) complex (Mo(O)₂L) has been synthesized and characterized by spectroscopic methods. The adsorption of Mo(O)₂L on the surface of silica-coated magnetite nanoparticles via hydrogen bonding led to the formation of (α-Fe₂O₃)–MCM-41–Mo(O)₂L as a heterogeneous catalyst. FT-IR and atomic absorption spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize and investigate the new nanocatalyst. A practical catalytic method for the efficient and highly selective oxidation of a wide range of olefins with hydrogen peroxide and tert-butyl hydroperoxide in ethanol over the prepared molybdenum nanocatalyst was investigated. Under reflux conditions, the oxidation of cyclooctene with tert-butyl hydroperoxide or hydrogen peroxide led to the formation of epoxide as the sole product. The catalyst was reused at least six times without a significant decrease in catalytic activity or selectivity, and without detectable leaching of the catalyst.     

β-Alanine-functionalized magnetic graphene oxide quantum dots: an efficient and recyclable heterogeneous basic catalyst for the synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-dione and 2,3-dihydroquinazolin-4(1H)-one derivatives

In this research, we report a novel synthesis of magnetic β-alanine-functionalized-graphene oxide quantum dots Fe₃O₄@GOQDs-N-(β-alanine) as a recyclable and eco-friendly heterogeneous nanocatalyst. The catalytic efficiency of these nanosheets was explored as a basic catalyst for a one-pot three-component synthesis of various 1H-pyrazolo[1,2-b]phthalazine-5,10-dione and 2,3-dihydroquinazolin-4(1H)-one derivatives. The reactions proceeded smoothly under mild and green conditions to afford the respected products in excellent yields. The structure of this newly fabricated catalyst was successfully confirmed by different analytical techniques such as Fourier transform infrared spectroscopy, X-ray diffraction, field emission-scanning electron microscopy, high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, vibrating sample magnetometry, and thermogravimetric analysis. The stability and recyclability of the catalyst were examined by performing the model reaction in six consecutive runs. The recovered catalyst from the first run was directly used for the next runs with no significant loss of catalytic activity.     

Heterogenized magnetic graphene oxide-supported N6-Schiff base Cu (II) complex as an exclusive nanocatalyst for synthesis of new pyrido[2,3-d]pyrimidine-7-carbonitrile derivatives

In this article, the synthesis of a novel and highly efficient recyclable and reusable heterogeneous nanocatalyst has been reported via the functionalizing of the Fe₃O₄-magnetized graphene oxide nanosheets with the N₆-Schiff base Cu (II) complex (GO/Fe₃O₄@SPNC). The structure of this novel nanocatalyst was determined by different analytical techniques such as FTIR, FE-SEM, TEM, TGA-DTG, and VSM. The catalytic activity of the synthesized GO/Fe₃O₄@SPNC nanocatalyst was explored for the synthesis of several new 2H-pyrido[3′,2′:6,7]pyrano[2,3-d]pyrimidine-7-carbonitrile derivatives with excellent yields. All new derivatives were fully identified by various spectral (¹H NMR, ¹³C NMR, FT-IR, ESI-MS) analyses. In addition, this nanocatalyst carried out satisfactory catalytic maintenance of activity and high chemical stability in the titled reactions after seven-time of recycling without substantial loss of leaching.     

Schiff base complex of palladium immobilized on magnetic nanoparticles: an efficient and recyclable nanocatalyst for CC coupling reactions

A Schiff base complex of palladium anchored on Fe₃O₄ magnetic nanoparticles as an efficient and magnetically reusable nanocatalyst is reported for C? C bond formation through Heck and Suzuki reactions. The catalyst was easily recovered and reused several times without significant loss of its catalytic efficiency or palladium leaching. The magnetic nanocatalyst was characterized using Fourier transform infrared and inductively coupled plasma atomic emission spectroscopies, thermogravimetric analysis, vibrating sample magnetometry, and transmission and scanning electron microscopies. Copyright © 2016 John Wiley & Sons, Ltd.     

Copper-based Schiff Base Complex Immobilized on Core-shell Fe3O4@SiO2 as a magnetically recyclable and highly efficient nanocatalyst for green synthesis of 2-amino-4H-chromene derivatives

Fe₃O₄-supported copper (II) Schiff-Base complex has been synthesized through post-modification with 1,3-phenylenediamine followed by further post-modification with salicylaldehyde and coordination with Cu(II) ion. The resulted Fe₃O₄@SiO₂-imine/phenoxy-Cu(II) magnetic nanoparticles (MNPs) were characterized by various techniques including SEM, TEM, XRD, XPS, EDX, VSM, FT-IR, and ICP. The catalytic activity as a magnetically recyclable heterogeneous catalyst for one-pot, three-component synthesis of 2-amino-4H-chromene derivatives was examined. The catalyst is efficient in the reaction and can be recovered by magnetic separation and recycled several times without significant loss in the catalytic activity.     

Imidazole-functionalized magnetic Fe3O4 nanoparticles: an efficient,green, recyclable catalyst for one-pot Friedländer quinoline synthesis

Research on Chemical Intermediates - An efficient and cost-effective procedure for preparation of Fe3O4 nanoparticles and supported Brønsted acidic ionic liquid...     

Sulfonic acid-functionalized Fe3O4-supported magnetized graphene oxide quantum dots: A novel organic-inorganic nanocomposite as an efficient and recyclable nanocatalyst for the synthesis of dihydropyrano[2,3-c]pyrazole and 4H-chromene derivatives

In this research, the main emphasis has been focused on the preparation of a novel Fe₃O₄-supported propane-1-sulfonic acid-grafted graphene oxide quantum dots (Fe₃O₄@GOQD-O-(propane-1-sulfonic acid)) that it was readily synthesized via a five-step procedure as a hitherto unreported magnetic nanocatalyst. This newly prepared Fe₃O₄@GOQD-O-(propane-1-sulfonic acid) nanocomposite was structurally well-established by different analytical techniques including Fourier transform infrared (FT-IR), X-ray diffraction (XRD), energy-dispersive X-ray (EDX), thermal gravimetric analysis (TGA), field emission gun-scanning electron microscope (FESEM), high-resolution transmission electron microscopy (HRTEM) and vibrating sample magnetometer (VSM) analyses. The high catalytic performance of this nanocomposite was exhibited in one-pot synthesis of dihydropyrano[2,3-c]pyrazole and 4H-chromene derivatives under mild conditions. Low reaction times, excellent yields of the products, benignity of the catalyst, easy reaction work-up and magnetic recyclability of the catalyst are the main advantages of the present protocol. Also, our research indicated that the Fe₃O₄@GOQD-O-(propane-1-sulfonic acid) could be reused up to five times without considerable loss of catalytic activity.     

Fe3O4@SiO2/collagen: An efficient magnetic nanocatalyst for the synthesis of benzimidazole and benzothiazole derivatives

In this project, Fe₃O₄@SiO₂ was synthesized and combined with collagen for the preparation of Fe₃O₄@SiO₂/collagen. It was characterized by FT-IR, ¹H NMR, VSM, XRD, EDX, SEM and TEM. This nanocatalyst has some interesting advantages such as facile synthetic procedure, high catalytic activity, easy separation and acceptable reusability. It was applied as an efficient nanocatalyst in the synthesis of benzimidazole and benzothiazole derivatives. This method offers several advantages including high yields, short reaction times, easy workup process and environmentally benign reaction conditions.     

The magnetic nanostructured natural hydroxyapatite (HAP/Fe3O4 NPs): an efficient,green and recyclable nanocatalyst for the synthesis of biscoumarin derivatives under solvent-free conditions

Research on Chemical Intermediates - The magnetic nanostructured natural hydroxyapatite (HAP/Fe3O4 NPs) as a novel magnetic nanocatalyst was synthesized and fully characterized. The excellent...     

Fe3O4@THAM-piperazine: a novel and highly reusable nanocatalyst for one-pot synthesis of 1,8-dioxo-octahydro-xanthenes and benzopyrans

Research on Chemical Intermediates - A novel magnetically heterogeneous nanocatalyst has been successfully synthesized via the immobilization of piperazine on tris (hydroxymethyl)...     

Mild preparation of 1H-pyrazolo[1,2-b]phthalazine-5,10-dione derivatives with magnetic Fe3O4 nanoparticles coated by (3-aminopropyl)-triethoxysilane as catalyst under ambient and solvent-free conditions

An efficient, one-pot quantitative procedure for preparation of 1H-pyrazolo[1,2-b]phthalazine-5,10-dione derivatives from four-component condensation reaction of hydrazine monohydrate, phthalic anhydride, malononitrile or ethyl cyanoacetate, and aromatic aldehydes in the presence of magnetic Fe₃O₄ nanoparticles coated by (3-aminopropyl)-triethoxysilane as catalyst under mild, ambient, and solvent-free conditions is described. Simple procedure, high yield, short reaction time, and environmentally benign method are advantages of this protocol. The magnetic Fe₃O₄ nanoparticles coated by (3-aminopropyl)-triethoxysilane can be recovered and reused several times without loss of activity.     

Fe3O4-supported N-pyridin-4-amine-grafted graphene oxide as efficient and magnetically separable novel nanocatalyst for green synthesis of 4H-chromenes and dihydropyrano[2,3-c]pyrazole derivatives in water

Research on Chemical Intermediates - Fe3O4-magnetized N-pyridin-4-amine-functionalized graphene oxide [Fe3O4@GO-N-(pyridin-4-amine)] was readily prepared via a three-step procedure. The synthesized...     

Fe3O4/SiO2 nanoparticles: an efficient and magnetically recoverable nanocatalyst for the one-pot multicomponent synthesis of diazepines

In this research, a new protocol for the one-pot multicomponent synthesis of diazepine derivatives using a 1,2-diamine, a linear or cyclic ketone, and an isocyanide in the presence of a catalytic amount of silica-supported iron oxide (Fe₃O₄/SiO₂) nanoparticles at ambient temperature in excellent yields is described.