Dendrimer-encapsulated Cu(Π) nanoparticles immobilized on superparamagnetic Fe 3 O 4 @SiO 2 nanoparticles as a novel recyclable catalyst for N -arylation of nitrogen heterocycles and green synthesis of 5-substituted 1 H -tetrazoles: Magnetic catalyst for N-arylation reaction and tetrazole synthesis

Well-defined nanomagnetic nitrilotriacetic acid complex of Cu(ii) supported on silica-coated nanosized magnetite: a new highly efficient and magnetically separable catalyst for C-N bond formation

A nitrilotriacetic acid (NTA) complex of Cu(ii) supported on silica-coated nanosized magnetite Fe3O4@SiO2-Pr-DEA-[NTA-Cu(ii)]2 was prepared as a new well-defined magnetically separable nanomaterial and fully characterized via IR, XRD, FESEM, TEM, TGA, DLS, BET, VSM, solid-state UV-vis spectroscopy, EDX, ICP-OES, and FESEM-EDX map analyses. Thereafter, it was successfully applied as a new easily magnetically separable and reusable heterogeneous nanocatalyst for the Buchwald-Hartwig C-N bond formation reaction in DMF at 110 °C. Using this method, various kinds of nitrogen heterocycles, such as imidazoles, 2-methyl-1H-imidazole, benzimidazole, indole, and 10H-phenothiazine as well as aliphatic secondary amines such as piperidine, piperazine, morpholine, dimethylamine, and diethylamine, were reacted with aryl halide compounds, and the desired products were obtained with good to excellent yields. In all cases, the applied catalyst could be recovered easily and rapidly using an external magnet and reused 7 times without significant loss of catalytic activity.

Immobilized Cu(0) nanoparticles on montmorillonite-modified with benzalkonium chloride (MMT-BAC@Cu(0)): as an eco-friendly and proficient heterogeneous nano-catalyst for green synthesis of 5-substituted 1H-tetrazoles

In this study, Cu(0) nanoparticles supported on organo-modified montmorillonite with benzalkonium chloride (MMT-BAC@Cu(0)) were synthesized and used as an eco-friendly and green heterogeneous catalyst for the synthesis of 5-substituted 1H-tetrazoles in mild media. The structure of the catalyst was investigated using various techniques including XRD, EDX, ICP, TEM, FE-SEM, and FT-IR. The advantages of availability, low cost, non-toxicity, and biocompatibility of clay were our focus in synthesizing this nanoclay catalyst. The method's advantages include good to excellent product yields, mild conditions, easy work-up, short reaction times, and easy reuse of the nanocatalyst.

Vancomycin-Loaded Fe3O4/MOF-199 Core/Shell Cargo Encapsulated by Guanidylated-β-Cyclodextrine: An Effective Antimicrobial Nanotherapeutic

This study describes an efficient antimicrobial drug delivery system composed of iron oxide magnetic nanoparticles (Fe₃O₄ NPs) coated by an MOF-199 network. Then, the prepared vancomycin (VAN)-loaded carrier was fully packed in a lattice of beta-cyclodextrin (BCD). For cell adhesion, beta-cyclodextrin has been functionalized with guanidine (Gn) groups within in situ synthetic processes. Afterward, drug loading efficiency and the release patterns were investigated through precise analytical methods. Confocal microscopy has shown that the prepared cargo (formulated as [VAN@Fe₃O₄/MOF-199]BCD-Gn) could be attached to the Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) bacterial cells in a higher rate than the individual VAN. The presented system considerably increased the antibacterial effects of the VAN with a lower dosage of drug. The cellular experiments such as the zone of inhibition and optical density (OD₆₀₀) have confirmed the enhanced antibacterial effect of the designed cargo. In addition, the MIC/MBC (minimum inhibitory and bactericidal concentrations) values have been estimated for the prepared cargo compared to the individual VAN, revealing high antimicrobial potency of the VAN@Fe₃O₄/MOF-199]BCD-Gn cargo.

Unsupported Copper Nanoparticles in the Arylation of Amines

Commercially available copper and copper (II) oxide nanoparticles (CuNPs and CuO NPs) were characterized using TEM and electronography methods to elucidate their true average size and composition. The catalytic amine arylation using unsupported copper nanoparticles differing in their size and copper oxidation state was investigated. The reaction of the model iodobenzene with n-octylamine was shown to be successfully catalyzed by CuNPs of average size 25 and 10/80 nm in the presence of the ligands such as 2-isobutyrylcyclohexanone (L1) and rac-1,1′-bi-2-naphthol (BINOL, L2), giving high yields (up to 95%) of the target N-octylaniline. CuO in bulk and nano forms was shown to be almost equally efficient in this process. Studies on the Cu-catalyzed amination of substituted iodobenzenes and 2-iodopyridine, as well as the arylation of different aliphatic amines and NH-heterocycles, verified that CuNPs (25 or 10/80 nm) with L1 and L2 are the most versatile and efficient nanocatalysts for a variety of substrates. Investigation of copper leaching under different conditions was carried out.

Supported Metal Catalysts for the Synthesis of N-Heterocycles

Nitrogen-containing heterocycles are important scaffolds for a large number of compounds with biological, pharmaceutical, industrial and optoelectronic applications. A wide range of different methodologies for the preparation of N-heterocycles are based on metal-catalyzed cyclization of suitable substrates. Due to the growing interest in Green Chemistry criteria over the past two decades, the use of supported metal catalysts in the preparation of N-heterocycles has become a central topic in Organic Chemistry. Here we will give a critical overview of all the solid supported metal catalysts applied in the synthesis of N-heterocycles, following a systematic approach as a function of the type of support: (i) metal catalysts supported on inorganic matrices; (ii) metal catalysts supported on organic matrices; (iii) metal catalysts supported on hybrid inorganic-organic matrices. In particular, we will try to emphasize the effective heterogeneity and recyclability of the described metal catalysts, specifying which studies were carried out in order to evaluate these aspects.

Metal-catalyzed reactions for the C(sp2)–N bond formation: achievements of recent years

The review deals with the main catalytic methods for the C(sp2)–N bond formation, including Buchwald–Hartwig palladium-catalyzed amination of aryl and heteroaryl halides, renaissance of the Ullmann chemistry, i.e., the application of catalysis by copper complexes to form the carbon–nitrogen bond, and Chan–Lam reactions of (hetero)arylboronic acids with amines. Also, oxidative amination with C–H activation, which has been booming during the last decade, is addressed. Particular attention is paid to achievements in the application of heterogenized catalysts.

The bibliography includes 350 references.

A decennary update on applications of metal nanoparticles (MNPs) in the synthesis of nitrogen- and oxygen-containing heterocyclic scaffolds

Heterocycles have been found to be of much importance as several nitrogen- and oxygen-containing heterocycle compounds exist amongst the various USFDA-approved drugs. Because of the advancement of nanotechnology, nanocatalysis has found abundant applications in the synthesis of heterocyclic compounds. Numerous nanoparticles (NPs) have been utilized for several organic transformations, which led us to make dedicated efforts for the complete coverage of applications of metal nanoparticles (MNPs) in the synthesis of heterocyclic scaffolds reported from 2010 to 2019. Our emphasize during the coverage of catalyzed reactions of the various MNPs such as Ag, Au, Co, Cu, Fe, Ni, Pd, Pt, Rh, Ru, Si, Ti, and Zn has not only been on nanoparticles catalyzed synthetic transformations for the synthesis of heterocyclic scaffolds, but also provide an inherent framework for the reader to select a suitable catalytic system of interest for the synthesis of desired heterocyclic scaffold.

UiO-66(Ti)-Fe3O4-WO3 photocatalyst for efficient ammonia degradation from wastewater into continuous flow-loop thin film slurry flat-plate photoreactor

This work presents the characterization of novel synthesized UiO-66(Ti)-Fe₃O₄-WO₃ magnetic photocatalyst and investigates their photocatalytic activity for the photodegradation of ammonia in a designed continuous flow-loop thin-film slurry flat-plate photoreactor (TFSR). Excellent ammonia degradation efficiency was achieved in the presence of the synthesized catalyst at ambient conditions using no more reactive oxidant species. Several independent variables involving catalyst mass, flowrate, pH, irradiation time and initial ammonia concentration as well as corresponding experiments were analyzed and design using the central composite design (CCD). The influence and significance of each parameter and their binary interactions were then evaluated by applying the analysis of variance. The ammonia degradation efficiency of 91.80 % with the desirability of 0.903 were obtained at optimum values of operational parameters including 550 mL/min,10, 0.125 g/L, 60 min and 30 mg/L for solution flowrate, pH, catalyst mass, irradiation time and initial ammonia concentration, respectively. Furthermore, the liquid phase products of ammonia degradation such as nitrate and nitrite ions were completely removed, and purified water was produced using the combination of reverse osmosis process and mixed resins beds. The photocatalyst mechanism study revealed that [Formula: see text] was the predominant reactive oxygen species in the ammonia photodegradation.

Cu(ii) immobilized on Fe3O4@HNTs–tetrazole (CFHT) nanocomposite: synthesis, characterization, investigation of its catalytic role for the 1,3 dipolar cycloaddition reaction, and antibacterial activity

In the present study, Cu(ii) immobilized on an Fe₃O₄@HNTs–tetrazole (CFHT) nanocomposite was designed and prepared. For this, halloysite nanotubes (HNTs) as natural mesoporous substances were modified during several chemical reactions. The synthesis of the CFHT nanocomposite was investigated step by step with the required physicochemical techniques such as FT-IR, EDX, SEM, TEM, XRD, VSM, TGA and CHNS analyses. After ensuring that the nanocomposite was successfully prepared, its catalytic application in the synthesis of the 5-substituted 1H-tetrazole derivatives via multicomponent reactions (MCRs) between aromatic aldehydes, malononitrile, and sodium azide was assessed. According to the experimental results, the prepared nanocomposite exhibited excellent capability for conducting this MCR reaction. All desired products were obtained in a short reaction time (30–40 min) with high productivity (90–97%) and without a complicated workup procedure. Furthermore, the magnetic property of the synthesized heterogeneous nanocomposite empowers it to be recovered and reused in five times successive reactions without any significant reduction in reaction efficiency. Moreover, the remarkable antibacterial activity of the nanocomposite against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was evaluated by agar diffusion and plate-count methods. The zones of inhibition were around 16 and 20 mm for E. coli and S. aureus bacteria, respectively. Also, colony analysis confirms the killing of bacteria by using the CFHT nanocomposite.

In the present study, Cu(ii) immobilized on an Fe₃O₄@HNTs–tetrazole (CFHT) nanocomposite was designed and prepared.

Anchoring of triethanolamine-Cu(II) complex on magnetic carbon nanotube as a promising recyclable catalyst for the synthesis of 5-substituted 1H-tetrazoles from aldehydes

The development of heterogenization of copper nanoparticles on conductive supports is very challenging and has received much attention. Here, we synthesize a practical, efficient, and inexpensive heterogeneous catalyst to grow stable metallic copper(II) nanoparticles on the surface of magnetic carbon nanotube (Fe₃O₄-CNT) catalyst support physically functionalized with triethanolamine (TEA) that acts as a low-cost and non-toxic ligand to capture the copper nanoparticles [Fe₃O₄-CNT-TEA-Cu(II)]. The as-prepared heterogeneous catalyst was characterized by different techniques, such as Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, thermogravimetric analysis, vibrating sample magnetometer, X-ray diffraction patterns, field-emission scanning electron microscopy, and atomic absorption spectroscopy analysis. The catalytic behavior of Fe₃O₄-CNT-TEA-Cu(II) was investigated in the preparation of 5-substituted 1H-tetrazole derivatives via one-pot, three-component reaction between aromatic aldehydes, hydroxylamine, and sodium azide. The low catalyst loading, wide substrate scope, use of inexpensive materials, simple separation of the catalyst from the reaction mixture by an external magnet, short reaction times, easy workup, affordability, and superb yield are some advantages of this protocol.