Recoverable Nanocatalyst Research Articles

Nano Cr(III) Schiff-base complex supported on magnetic Fe3O4@SiO2: efficient, heterogeneous, and recoverable nanocatalyst for chemoselective synthesis of 1,2-disubstituted benzimidazoles

Nano Cr(III) Schiff-base complex supported on magnetic Fe3O4@SiO2: efficient, heterogeneous, and recoverable nanocatalyst for chemoselective synthesis of 1,2-disubstituted benzimidazoles

A Review of Magnetically Recyclable Nanocatalysts for the Synthesis of Quinazoline and its Derivatives

Abstract: The utility of quinazoline scaffolds as intermediates in new medicinal drug development and discovery has grown in recent decades. The quinazoline framework is a valuable pharmacophore, intermediate, and interesting building block with a wide range of pharmacological activities that has piqued the interest of researchers in developing novel synthetic strategies in medicinal chemistry. In contrast to time-, solvent-, and energy-consuming separation approaches, magnetic separation is an effective method for the quick separation of catalysts from reaction media. Nowadays, magnetically separable nanoparticles have recently gained much interest from chemist in recent research due to their remarkable catalytic activity in various chemical transformations. Many research articles have been published for the synthesis of quinazoline derivatives based on utilizing nanoparticles as a catalyst because of the significant role that biological quinazoline plays in medicinal chemistry. In the present review study, we summarize the surface functionalization of mesoporous silica, metal organocatalysts, ionic liquids, and polymer-supported magnetic nanoparticles and their applications as magnetically recoverable nanocatalysts in the efficient synthetic methods of biologically active quinazoline and its derivatives.

Ferrite Nanoparticles as Catalysts in Organic Reactions: A Mini Review

Ferrites have excellent magnetic, electric, and optical properties that make them an indispensable choice of material for a plethora of applications, such as in various biomedical fields, magneto–optical displays, rechargeable lithium batteries, microwave devices, internet technology, transformer cores, humidity sensors, high-frequency media, magnetic recordings, solar energy devices, and magnetic fluids. Recently, magnetically recoverable nanocatalysts are one of the most prominent fields of research as they can act both as homogeneous and heterogenous catalysts. Nano-ferrites provide a large surface area for organic groups to anchor, increase the product and decrease reaction time, providing a cost-effective method of transformation. Various organic reactions were reported, such as the photocatalytic decomposition of a different dye, alkylation, dehydrogenation, oxidation, C–C coupling, etc., with nano-ferrites as a catalyst. Metal-doped ferrites with Co, Ni, Mn, Cu, and Zn, along with the metal ferrites doped with Mn, Cr, Cd, Ag, Au, Pt, Pd, or lanthanides and surface modified with silica and titania, are used as catalysts in various organic reactions. Metal ferrites (MFe2O4) act as a Lewis acid and increase the electrophilicity of specific groups of the reactants by accepting electrons in order to form covalent bonds. Ferrite nanocatalysts are easily recoverable by applying an external magnetic field for their reuse without significantly losing their catalytic activities. The use of different metal ferrites in different organic transformations reduces the catalyst overloading and, at the same time, reduces the use of harmful solvents and the production of poisonous byproducts, hence, serving as a green method of chemical synthesis. This review provides insight into the application of different ferrites as magnetically recoverable nanocatalysts in different organic reactions and transformations.

Imidazolium organometallic complex of palladium on Fe3O4 nanoparticles as selective and magnetically recoverable nanocatalyst for C‐C cross‐coupling reactions

The synthesis of an efficient heterogeneous nanocatalyst was prepared by the anchoring of palladium complex on the surface of an imidazolium‐based ionic liquid‐functionalized Fe3O4 (Pd‐imidazolium@Fe3O4 NPs). The nanocatalyst, Pd‐imidazolium@Fe3O4 NPs, was characterized by Raman, X‐ray diffraction (XRD), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy (EDX), fourier transform infrared (FT‐IR), inductively coupled plasma (ICP), and vibrating sample magnetometer (VSM) techniques. The catalytic performance of this novel nanocatalyst was evaluated in the Heck––Mizoroki and Suzuki–Miyaura cross‐coupling reactions under mild conditions using PEG‐400 as a green and biodegradable solvent. The nanocatalyst exhibited high catalytic activity for both cross‐coupling reactions. Furthermore, this stable nanocatalyst can be easily removed and recovered from the reaction mixture and reused for at least eight consecutive cycles without a discernible decrease in the catalytic activity. Also, the recovered Pd‐imidazolium@Fe3O4 NPs was characterized by FT‐IR, XRD, scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, and atomic absorption spectroscopy techniques.

Facile Synthesis of Magnetic Bentonite–Chitosan–Pd Nanocomposite: As a Recoverable Nanocatalyst for Reduction of Nitroarenes and Suzuki–Miyaura Reaction

Facile Synthesis of Magnetic Bentonite–Chitosan–Pd Nanocomposite: As a Recoverable Nanocatalyst for Reduction of Nitroarenes and Suzuki–Miyaura Reaction

Synthesis of (E)-2-(Chloro (Phenyl) Methylene)-1-(6-Chloroquinoxalin-2-yl) Hydrazine Derivatives by Reusable Fe3O4 Nano Powder at Room Temperature

A multicomponent reaction (MCR) for the synthesis of five novel N'-(6-chloroquinoxalin-2-yl) benzohydrazide derivatives in excellent yields at room temperature have been achieved via a reaction between 1-(6-chloroquinoxalin-2-yl) hydrazine was added 4-chloroethyl benzoyl chloride followed by the addition of Fe3O4 nanoparticles. This was applied as an efficient and recoverable nanocatalyst for the one‐pot synthesis of hydrazine Derivatives. The catalyst was magnetically recovered and reused for 4 consecutive cycles without significant loss of its activity and selectivity. Fe3O4 Nano catalyst was prepared by the co-precipitation method and characterized by X-ray diffraction (XRD), FT-IR, TEM, VSM, and analyses. This study presents an efficient multicomponent protocol, which provides several advantages, such as short reaction times, high yields, and easy working up this work.

Magnetic ethylene-based periodic mesoporous organosilica supported palladium: An efficient and recoverable nanocatalyst for Suzuki reaction.

In the present study, a novel magnetic ethylene-based periodic mesoporous organosilica supported Pd-Schiff base complex (Fe3O4@PMO/SB-Pd) was prepared, characterized and applied as a recoverable nanocatalyst for green synthesis of Suzuki products. Chemical composition, magnetic and thermal behavior, morphology and particle size of Fe3O4@PMO/SB-Pd were investigated by using FT-IR, TGA, EDX, VSM, PXRD, TEM and Scanning electron microscopy (SEM) analyses. The Fe3O4@PMO/SB-Pd nanocomposite was applied as an efficient nanocatalyst in the Suzuki reaction under ultrasonic conditions giving corresponding products in high yield. Some advantages of this study are simple purification of products, the use of water solvent, easy catalyst separation, short reaction time and high catalyst efficiency and recoverability.

Novel neodymium complex on MCM‐41 magnetic nanocomposite as a practical, selective, and returnable nanocatalyst in the synthesis of tetrazoles with antifungal properties in agricultural

This project reports a simple procedure for the synthesis and characterization of neodymium on MCM‐41 magnetic nanoparticles (MNPs) as a reusable nanocatalyst. First, magnetite (Fe3O4) MNPs were prepared by chemical co‐precipitation procedure from FeCl3 hexahydrate and FeCl2 tetrahydrate in basic NH3 solution. At the second step, MCM‐41 magnetic nanocomposite (MCM‐41 MNC) was prepared by Fe3O4 doping into mesoporous MCM‐41 channels. At the third step, a novel neodymium Schiff base complex was immobilized on MCM‐41 MNC. At the fourth step, this catalyst (Nd‐LArg‐5BrSalen@MNC) was used as practicable and magnetically recoverable nanocatalyst in the homoselective synthesis of tetrazoles. This nanocatalyst was characterized via several analysis, for example, TGA, TEM, UV, SEM, FT‐IR, SEM‐EDS, VSM, ICP, XRD, WDX, and BET. All tetrazole products were synthesized with high yield in a short time. Despite high catalytic activity of neodymium, it has rarely used as a catalyst in the synthesis of organic compounds. All synthesized organic compounds were identified by 1H NMR, FT‐IR, and physical properties. Nd‐LArg‐5BrSalen@MNC nanocatalyst displays high activity, good selectivity, stability, and more important facile magnetic separation. Nd‐LArg‐5BrSalen@MNC nanocatalyst can be isolated and used again for several times consecutively without considerable loss of its catalytic activity. The recycled catalyst was characterized by SEM, EDS, WDX, XRD, and FT‐IR techniques and showed a good match with the fresh catalyst. Also, the antifungal activity of the some tetrazole derivatives was studied against Fusarium oxysporum (rot disease of chickpea root) and Botrytis cinerea (gray mold of strawberry) using the paper disk method on PDA culture medium.

NiFe2O4@SiO2-Cu as a novel and efficient magnetically recoverable nanocatalyst for regioselective synthesis of β-thiol-1,2,3-triazoles under benign conditions.

A green, mild and eco-friendly approach for the three component one-pot regioselective synthesis of 1,2,3-triazoles from thiiranes has been introduced in the presence of NiFe2O4@SiO2-Cu as a new and recoverable nanocatalyst. First, the NiFe2O4 nanoparticles have been produced through a solid-state reaction of hydrated nickel sulfate, hydrated iron(iii) nitrate, NaOH and NaCl salts, and then calcined at 700 °C. Next, in order to protect the ferrite particles from oxidation and aggregation, the NiFe2O4 was core-shelled using tetraethyl orthosilicate (TEOS) and converted to NiFe2O4@SiO2. Finally, the novel NiFe2O4@SiO2-Cu nanocomposite was successfully prepared by adding copper(ii) chloride solution and solid potassium borohydride. The catalyst has been characterized by FT-IR, SEM, EDX, VSM, ICP-OES, TEM and XRD techniques. The 1,3-dipolar cyclization of 1,2,3-triazoles was performed successfully in water at room temperature in high yields. The recoverability and reusability of the heterogeneous NiFe2O4@SiO2-Cu have also been investigated using VSM, SEM and FT-IR analyses. The catalyst was used four times in consecutive runs without considerable loss of activity. The presented procedure provides significant benefits such as using water as a green solvent, absence of hazardous organic solvents, high yields, benign conditions and recyclability of the magnetic catalyst.

Ionic liquid immobilized on modified magnetic FSM-16: an efficient and magnetically recoverable nanocatalyst.

In the present article, a nanocomposite was prepared by immobilizing ionic liquid on the magnetic mesoporous FSM-16 with a core-shell structure (Fe3O4@FSM-16-SO3/IL). Subsequently, the structural properties of the synthesized nanocatalyst were characterized and analyzed by various techniques such as XRD, FT-IR, TEM, FE-SEM, BET, VSM, TGA, and EDS. Fe3O4@FSM-16-SO3/IL was used as a recoverable and efficient nanocatalyst for the synthesis of polyhydroquinoline derivatives. The magnetic nanocatalyst showed remarkable stability and reusability and was reused six consecutive times without considerable loss of its activity.

Supramolecular Cu(ii) nanoparticles supported on a functionalized chitosan containing urea and thiourea bridges as a recoverable nanocatalyst for efficient synthesis of 1H-tetrazoles.

A cost-effective and convenient method for supporting of Cu(ii) nanoparticles on a modified chitosan backbone containing urea and thiourea bridges using thiosemicarbazide (TS), pyromellitic dianhydride (PMDA) and toluene-2,4-diisocyanate (TDI) linkers was designed. The prepared supramolecular (CS-TDI-PMDA-TS-Cu(ii)) nanocomposite was characterized by using Fourier-transform infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FESEM), thermogravimetry/differential thermogravimetry analysis (TGA/DTA), energy-dispersive X-ray spectroscopy (EDS), EDS elemental mapping and X-ray diffraction (XRD). The obtained supramolecular CS-TDI-PMDA-TS-Cu(ii) nanomaterial was demonstrated to act as a multifunctional nanocatalyst for promoting of multicomponent cascade Knoevenagel condensation/click 1,3-dipolar azide-nitrile cycloaddition reactions very efficiently between aromatic aldehydes, sodium azide and malononitrile under solvent-free conditions and affording the corresponding (E)-2-(1H-tetrazole-5-yl)-3-arylacrylenenitrile derivatives. Low catalyst loading, working under solvent-free conditions and short reaction time as well as easy preparation and recycling, and reuse of the catalyst for five consecutive cycles without considerable decrease in its catalytic efficiency make it a suitable candidate for the catalytic reactions promoted by Cu species.

Recyclable mesalamine-functionalized magnetic nanoparticles (mesalamine/GPTMS@SiO2@Fe3O4) for tandem Knoevenagel-Michael cyclocondensation: grinding technique for the synthesis of biologically active 2-amino-4H-benzo[b]pyran derivatives.

In the present study, mesalamine-functionalized on magnetic nanoparticles (mesalamine/GPTMS@SiO2@Fe3O4) is fabricated as an efficient and magnetically recoverable nanocatalyst. The as-prepared nanocatalyst was successfully synthesized in three steps using a convenient and low-cost method via modification of the surface of Fe3O4 nanoparticles with silica and GPTMS, respectively, to afford GPTMS@SiO2@Fe3O4. Finally, treatment with mesalamine as a powerful antioxidant generates the final nanocatalyst. Then, its structure was characterized by FT-IR, SEM, TEM, EDX, XRD, BET, VSM, and TGA techniques. The average size was found to be approximately 38 nm using TEM analysis and the average crystallite size was found to be approximately 27.02 nm using XRD analysis. In particular, the synthesized nanocatalyst exhibited strong thermal stability up to 400 °C and high magnetization properties. The activity of the synthesized nanocatalyst was evaluated in the tandem Knoevenagel-Michael cyclocondensation of various aromatic aldehydes, dimedone and malononitrile under a dry grinding method at room temperature to provide biologically active 2-amino-4H-benzo[b]pyran derivatives products in a short time with good yields. The presented procedure offers several advantages including gram-scale synthesis, good green chemistry metrics (GCM), easy fabrication of the catalyst, atom economy (AE), no use of column chromatography, and avoiding the generation of toxic materials. Furthermore, the nanocatalyst can be reused for 8 cycles with no loss of performance by using an external magnet.

Synthesis of tetrazoles catalyzed by a new and recoverable nanocatalyst of cobalt on modified boehmite NPs with 1,3-bis(pyridin-3-ylmethyl)thiourea.

In the first part of this work, boehmite nanoparticles (BNPs) were synthesized from aqueous solutions of NaOH and Al(NO3)3·9H2O. Then, the BNPs surface was modified using 3-choloropropyltrimtoxysilane (CPTMS) and then 1,3-bis(pyridin-3-ylmethyl)thiourea ((PYT)2) was anchored on the surface of the modified BNPs (CPTMS@BNPs). In the final step, a complex of cobalt was stabilized on its surface (Co-(PYT)2@BNPs). The final obtained nanoparticles were characterized by FT-IR spectra, TGA analysis, SEM imaging, WDX analysis, EDS analysis, and XRD patterns. In the second part, Co-(PYT)2@BNPs were used as a highly efficient, retrievable, stable, and organic-inorganic hybrid nanocatalyst for the formation of organic heterocyclic compounds such as tetrazole derivatives. Co-(PYT)2@BNPs as a novel nanocatalyst are stable and have a heterogeneous nature; therefore, they can be recovered and reused again for several consecutive runs without any re-activation.

Oxovanadium(IV)‐salophen covalently immobilized on silica‐coated Fe3O4 nanoparticles: A magnetically recoverable nanocatalyst for the selective oxidation of sulfides

The current study introduces an approach toward the development of heterogeneous, magnetically recoverable oxovanadium(IV)‐salophen complex to employ in the selective oxidation of sulfides using H2O2 as oxidant. A salophen ligand containing hydroxyl functional group was synthesized, which is conducive to successful, covalent immobilization of metal complex onto the silica‐modified Fe3O4 magnetic nanoparticles (SMNPs). This type of metal anchoring is achieved through an intermolecular condensation reaction. The in‐depth investigation on the catalyst (Fe3O4@SiO2@VO(salophen)) productivity and lifetime in the oxidation of a wide range of linear and aromatic sulfides is well represented and discussed. The use of the current catalyst in the selective oxidation of prototype substrate (methyl phenyl sulfide) resulted in an appreciable increase in the selectivity toward the desired sulfoxide (92%) and conversion rate (95%) compared with similar studies, reported to this day. Analytical techniques such as field emission scanning electron micrograph (FE‐SEM), energy‐dispersive X‐ray spectroscopy (EDX), Fourier transform infrared (FT‐IR), X‐ray diffraction (XRD) analysis, and inductively coupled plasma optical emission spectrometer (ICP‐OES) provided data on structural/compositional characterization of materials in catalyst preparation steps.

Multi-component Synthesis of Novel Triazines using Fe3O4@SP@VIC as a Green, Effective and Magnetically Recoverable Nanocatalyst

Multi-component Synthesis of Novel Triazines using Fe3O4@SP@VIC as a Green, Effective and Magnetically Recoverable Nanocatalyst

Facile synthesis of green and efficient copper-based magnetically recoverable nanocatalyst for the reduction of nitrophenol derivatives

A green and facile preparation of CuO/SiO2@Fe3O4 nanocatalysts (CuO(G)/SiO2@Fe3O4 and CuO(L)/SiO2@Fe3O4) were developed using glucose and lactose as grafting agent to place copper oxide on the surface of the magnetic nanoparticles by hydrothermal method. The structure and morphology of the prepared nanocatalysts were identified using FT-IR. XRD, XPS, BET, VSM, TGA, EDX-Mapping, FE-SEM, HRTEM and ICP-OES analyses. The catalytic activity of nanocatalysts was investigated to reduce 4-nitrophenol, 2-nitrophenol, 3-nitroaniline and 4-nitroaniline compounds using the UV–Vis spectrum. In reducing 4-nitrophenol using CuO(G)/SiO2@Fe3O4 and CuO(L)/SiO2@Fe3O4, the apparent rate constant (Kapp) were obtained 0.38 and 0.28 min−1, and activity factors (k’) were 3251 and 1396 s−1 g−1, respectively. High conversion in a short time and good stability were the advantages of the prepared nanocatalysts. The magnetic nature of the catalysts makes them easily recoverable and easy to use in multiple cycles.

Palladium nanoparticles stabilized on the amino acids-functionalized Fe3O4 as the magnetically recoverable nanocatalysts for Heck and Suzuki reactions

Regarding the green chemistry goals, well-organized processes for catalyst separation and reuse have drawn much attention in the past few decades. The strategy of magnetic separation offers a convenient approach for recycling catalysts by applying an appropriate magnetic field. In this paper, a palladium nanoparticle-based catalyst that is stabilized on the glutathione and aspartic acid-functionalized superparamagnetic Fe3O4 nanoparticles has been prepared by an eco-friendly, economical and effective procedure. The catalytic performance of these novels, highly active and recoverable catalysts was investigated under low loading of the supported palladium nanoparticles for Heck and Suzuki reactions. Under optimal reaction conditions, the nanocomposites afford the corresponding products in excellent yield. The catalysts could be easily separated from the reaction system and efficiently recycled for four consecutive runs without a remarkable loss of their activity. The structural and magnetic properties of the catalysts were identified by Fourier transform infrared (FT-IR), Powder X-ray diffraction (XRD), scanning electron microscopy (SEM), vibration sample magnetometer (VSM), inductively coupled plasma atomic emission analysis (ICP-AES) and thermogravimetric analysis (TGA).

Efficient synthesis of 1,3-naphtoxazine derivatives using reusable magnetic catalyst (GO-Fe3O4–Ti(IV)): anticonvulsant evaluation and computational studies

A series of 2-aryl/alkyl-2,3-dihydro-1H-naphtho[1,2-e][1,3]oxazines (S1–S11) were synthesized with an eco-friendly and recoverable nanocatalyst (GO-Fe3O4–Ti(IV)) as an efficient magnetic composite. The new nanocatalyst was characterized by FT-IR, XRD and, EDS analysis. A conformable procedure, easy to work up and having a short reaction time with high yields are some advantages of this method. The new catalyst is also thermal-stable, reusable and, environment-friendly. The chemical structures of the synthesized 1,3-oxazine compounds were confirmed by comparing their melting points with those reported in literature. Then, the anticonvulsant activity of these compounds was assessed by the intraperitoneal pentylenetetrazole test (ipPTZ). Compounds S10 and S11 displayed considerable activity against chemically-induced seizure tests. The molecular simulation was also done to achieve their binding affinities as γ‐aminobutyric acid A (GABA‐A) receptor agonists as an assumptive mechanism of their anticonvulsant action. The result of molecular studies represented strongly matched with biological activity. Molecular docking simulation of the potent compound (S10) and diazepam as the positive control was performed and some critical residues like Thr262, Asn265, Met286, Phe289, and Val290 were identified. Based on the anticonvulsant results and also in silico ADME predictions, S11 can be to become a potential drug candidate as an anticonvulsant agent.

Synthesis, properties and catalysis of quantum dots in C–C and C-heteroatom bond formations

Abstract Luminescent quantum dots (QDs) represent a new form of carbon nanomaterials which have gained widespread attention in recent years, especially in the area of chemical sensing, bioimaging, nanomedicine, solar cells, light-emitting diode (LED), and electrocatalysis. Their extremely small size renders some unusual properties such as quantum confinement effects, good surface binding properties, high surface‐to‐volume ratios, broad and intense absorption spectra in the visible region, optical and electronic properties different from those of bulk materials. Apart from, during the past few years, QDs offer new and versatile ways to serve as photocatalysts in organic synthesis. Quantum dots (QD) have band gaps that could be nicely controlled by a number of factors in a complicated way, mentioned in the article. Processing, structure, properties and applications are also reviewed for semiconducting quantum dots. Overall, this review aims to summarize the recent innovative applications of QD or its modified nanohybrid as efficient, robust, photoassisted redox catalysts in C–C and C-heteroatom bond forming reactions. The recent structural modifications of QD or its core structure in the development of new synthetic methodologies are also highlighted. Following a primer on the structure, properties, and bio-functionalization of QDs, herein selected examples of QD as a recoverable sustainable nanocatalyst in various green media are embodied for future reference.

Magnetic Nanoparticles Supported Copper Nanocomposite: A Highly Active Nanocatalyst for Synthesis of Benzothiazoles and Polyhydroquinolines

A novel magnetically recoverable copper nanocatalyst was fabricated via the immobilization of a copper complex on the surface of silica-coated magnetic nanoparticles modified with a novel Schiff base ligand [Fe3O4@SiO2-bis(aminopyridine)-Cu]. FT-IR spectroscopy, SEM, TEM, EDX, VSM, XRD, XPS, TGA and AAS, ICP-OES techniques were applied to characterize the structure of the as-fabricated [Fe3O4@SiO2-bis(aminopyridine)-Cu(II)] nanocomposite. TEM and SEM analysis confirmed that the typical silica shell thickness was assessed to be around 20 nm. Catalytic studies revealed that the Fe3O4@SiO2-bis(aminopyridine)-Cu(II) nanocomposite is a highly efficient and green nanocatalyst for the synthesis of benzothiazoles and polyhydroquinolines. The [Fe3O4@SiO2-bis(aminopyridine)-Cu(II)] nanocatalyst could be easily recovered by a simple magnetic separation and recycled at least 6 times without deterioration in catalytic activity.