Magnetic nanoparticles grafted with β-cyclodextrin–polyurethane polymer as a novel nanomagnetic polymer brush catalyst for nucleophilic substitution reactions of benzyl halides in water

Preparation of Au/ZnO/Fe3O4 Composite for Degradation of Tartrazine under Visible Light

Zinc oxide has been shown to be a potential photocatalyst under UV light but its catalytic activity is limited under visible light due to its wide bandgap energy and rapid recombination of electrons and holes. Besides the catalytic recovery is a challenging issue because of its dispersion in solution. Previous work has shown that the interaction of gold nanoparticles with ZnO can reduce the band gap energy (Eg) and plasmon resonance (SPR) as well as the formation of the Schottky barrier in Au/ZnO composite can reduce the recombination of electrons and holes. In this study, Au/ZnO/Fe3O4 (AZF) composites were prepared by a simple mixing method using polyvinyl alcohol (PVA) as a binder. As-prepared composites were characterized by Scanning Electron Microscope (SEM), Energy Dispersive X-ray Spectroscopy (EDS), X-ray Diffraction (XRD), UV-Vis Diffuse Reflectance (UV-Vis-DR), and Fourier Transform Infra Red (FT-IR). The catalytic efficiency of as-prepared samples was evaluated through the decomposition of tartrazine (TA), a colorant that is difficult to decompose in wastewater and has harmful effects on human health. The effects of reaction parameters such as the content of PVA, solution pH, and oxidizing agents (O2 and H2O2) on the catalytic efficiency were studied. The AZF at PVA of 0.0125 g showed the highest performance among as-prepared samples. With the presence of 12 mM H2O2 in the catalyst system, the degradation efficiency and reaction rate of TA in composite increased to 81.5% and 0.020 min−1, respectively. At this condition, photocatalysis and Fenton system catalysis occurred together. The catalytic mechanism of Tartrazine (TA) on composite was proposed and the reaction of TA was studied by the first-order kinetic model. Copyright © 2023 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0). 

Synthesis of novel pyrano[2,3-f]chromene-dione derivatives using phosphoric acid-functionalized silica-coated Fe3O4 nanoparticles as a new reusable solid acid nanocatalyst

In this research, the synthesis of novel indeno[1,2-b]pyrano[2,3-f]chromene-2,12(13H)-dione derivatives in the presence of a newly introduced magnetically recoverable nanosolid acid catalyst is reported. At the first, phosphoric acid-functionalized silica-coated Fe₃O₄ nanoparticles (Fe₃O₄@SiO₂-(CH₂)₃OPO₃H₂) were prepared and well characterized using infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), and energy-dispersive X-ray spectroscopy (EDS) techniques. Then, the catalytic activity of the prepared Fe₃O₄@ SiO₂-(CH₂)₃OPO₃H₂ nanocatalyst was investigated for the synthesis of novel indeno[1,2-b]pyrano[2,3-f]chromene-2,12(13H)-dione derivatives via a one-pot and three-component condensation between 5,7-dihydroxy-4-methylcoumarin, indane-1, 3-dione, and various aromatic aldehydes under solvent-free condition. All the products are unknown, and their characterization was performed with the spectral data information obtained from their FT-IR, ¹H and ¹³CNMR, elemental analysis, and their melting points. The reusability study of the introduced nanosolid acid catalyst showed that the catalytic stability is almost completely remained up to five consecutive runs.

Understanding the fragmentation of microplastics into nano-plastics and removal of nano/microplastics from wastewater using membrane, air flotation and nano-ferrofluid processes

Nano/microplastics (NPs/MPs), a tiny particle of plastic pollution, are known as one of the most important environmental threats to marine ecosystems. Wastewater treatment plants can act as entrance routes for NPs/MPs to the aquatic environment as they breakdown of larger fragments of the plastic component during the treatment process; therefore, it is necessary to remove NPs/MPs during the wastewater treatment process. In this study, understanding the effect of water shear force on the fragmentation of larger size MPs into smaller MPs and NPs and their removal by air flotation and nano-ferrofluid (i.e., magnetite and cobalt ferrite particle as a coagulant) and membrane processes were investigated as a proof-of-concept study. It is found that a two-blade mechanical impeller could fragment MPs from 75, 150 and 300 μm into mean size NPs/MPs of 0.74, 1.14 and 1.88 μm, respectively. Results showed that the maximum removal efficiency of polyethylene, polyvinyl chloride and polyester was 85, 82 and 69%, respectively, in the air flotation process. Increasing the dose of behentrimonium chloride surfactant from 2 to 10 mg/L improved the efficiency of the air flotation process for NPs/MPs removal. It is also found that the removal efficiency of NPs/MPs by the air flotation system depends on solution pH, size, and types of NPs/MPs. This study also found a less significant removal efficiency of NPs/MPs by both types of ferrofluid used in this study with an average removal of 43% for magnetite and 55% for cobalt ferrite. All three plastics tested had similar removal efficiency by the nano-ferrofluid particles, meaning that this removal technique does not rely on the plastic component type. Among all the process tested, both ultrafiltration and microfiltration membrane processes were highly effective, removing more than 90% of NPs/MPs fragment particles. Overall, this study has confirmed the effectiveness of using air flotation and the membrane process to remove NPs/MPs from wastewater.

Magnetic Nanoparticles Functionalized with Copper Hydroxyproline Complexes as an Efficient, Recoverable, and Recyclable Nanocatalyst: Synthesis and Its Catalytic Application in a Tandem Knoevenagel-Michael Cyclocondensation Reaction

A novel catalyst has been afforded by attaching of a Cu(proline)₂ complex to magnetic nanoparticles through cheap, simple, and readily available chemicals. This catalyst was characterized by Fourier transform infrared, energy-dispersive X-ray, X-ray diffraction, vibrating-sample magnetometry, transmission electron microscopy, scanning electron microscopy, and inductively coupled plasma analyses. The catalytic activity of the Fe₃O₄@NH₂@TCT@HProCu nanocatalyst was investigated in a green and effective synthesis of pyran derivatives in high yields by applying three-component reactions of malononitrile, dimedone, and aldehydes in ethanol. Conversion was high under optimal conditions. The obtained nanocatalyst could be easily separated from the mixture of the reaction and was recyclable nine times via a simple magnet without considerable reduction of its catalytic efficiency. Operational simplicity, high product yields, environmental friendliness, ecofriendliness, economical processing, and easy workup are the features of this methodology.

Recent developments in the nanomaterial-catalyzed green synthesis of structurally diverse 1,4-dihydropyridines

1,4-Dihydropyridine (1,4-DHP), a privileged heterocyclic scaffold, has been extensively utilized in various biological and therapeutic applications. In this review article, we discussed the role of different nano-catalysts, nanoflakes, nanocomposites, and other green-supported nanomaterials in the synthesis of a biologically active and vital pharmaceutical precursor 1,4-DHP and its derivatives such as polyhydroquinoline, benzopyranopyridines, and dihydropyridine since 2015. It is evident that although the use of various tailored nanostructures under different conditions to optimize the synthesis of 1,4-DHP and its compounds has provided sustainable and efficient proposals, yet the development of greener practices in the synthesis of 1,4-DHPs, which can be applied to design new synthetic routes and sequences in process development, is a far-reaching task to be accomplished.

Single pot multicomponent approaches using different nanomaterials as green catalysts for synthesis of 1,4-dihydropyridine (1,4-DHP), a privileged heterocyclic scaffold with vital biological and therapeutic applications are reviewed.

Thiocyanation and 2-Amino-1,3-thiazole Formation in Water Using Recoverable and Reusable Glycosylated Resorcin[4]arene Cavitands

A family of three spatially directional resorcin[4]arene cavitand glycoconjugates (RCGs) have been applied as efficient recoverable and reusable inverse phase transfer catalysts for eco- and environmentally friendly thiocyanation and 2-amino-1,3-thiazole formation reactions in water. The results show that RCGs (1 mol %) were capable of hosting and catalyzing various water-insoluble bromo/thiocyanato substrates in water without the use of any co-organic solvents. The recoverability and reusability of RCG catalytic systems, that is, RCG1 and RCG3, were also examined upon a simple extraction of the desired products using DCM or ethyl acetate, followed by subjecting the recovered aqueous solution containing the RCG catalysts to the next reaction cycles.

One-Pot Access to Diverse Functionalized Pyran Annulated Heterocyclic Systems Using SCMNPs@BPy-SO3H as a Novel Magnetic Nanocatalyst

The SCMNPs@BPy-SO3H catalyst was prepared and characterized using Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), Vibrating Sample Magnetometry (VSM), Energy Dispersive X-ray Spectroscopy (EDX), X-ray Diffraction (XRD), and Scanning Electron Microscopy (SEM). Afterwards, its capability was efficiently used to promote the one-pot, three-component synthesis of pyrano[2,3-c]pyrazole and 2-amino-3-cyano-pyrano[3,2-c]chromen-5(4H)-one derivatives. The strategy resulted in the desired products with excellent yields and short reaction times. The SCMNPs@BPy-SO3H catalyst was readily recovered using a permanent magnetic field and it was reused in six runs with a slight decrease in catalytic activity. Copyright © 2020 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

A convenient method for synthesis of terpyridines via a cooperative vinylogous anomeric based oxidation

The presented study is the first report of the synthesis of terpyridines in the presence of a nanomagnetic catalyst instead of harmful reagents. Herein, Fe3O4@O2PO2(CH2)2NH3 +CF3CO2 - as a retrievable nanocatalyst with magnetic properties was applied for the multi-component reaction between acetylpyridine derivatives (2 or 3 or 4-isomer), aryl aldehydes and ammonium acetate under conventional heating conditions in the absence of any solvent. The derived terpyridines were obtained with acceptable yields and brief reaction times via a cooperative vinylogous anomeric based oxidation route. Fe3O4@O2PO2(CH2)2NH3 +CF3CO2 - showed a high capability for recovery and reuse in the mentioned reaction.

Helicoidal Patterning of Gold Nanorods by Phase Separation in Mixed Polymer Brushes

The spatial distribution of polymer ligands on the surface of nanoparticles (NPs) is of great importance because it determines their interactions with each other and with the surrounding environment. Phase separation in mixtures of polymer brushes has been studied for spherical NPs; however, the role of local surface curvature of nonspherical NPs in the surface phase separation of end-grafted polymer ligands remains an open question. Here, we examined phase separation in mixed monolayers of incompatible polystyrene and poly(ethylene glycol) brushes end-capping the surface of gold nanorods in a good solvent. By varying the molar ratio between these polymers, we generated a range of surface patterns, including uniform and nonuniform polystyrene shells, randomly distributed polystyrene surface patches, and, most interestingly, a helicoidal pattern of polystyrene patches wrapping around the nanorods. The helicoidally patterned nanorods exhibited long-term colloidal stability in a good solvent. The helicoidal wrapping of the nanorods was achieved for the mixtures of polymers with different molecular weights and preserved when the quality of the solvent for the polymers was reduced. The helicoidal organization of polymer patches on the surface of nanorods can be used for templating the synthesis or self-assembly of helicoidal multicomponent nanomaterials.

A study on the removal of propyl, butyl, and benzyl parabens via newly synthesised ionic liquid loaded magnetically confined polymeric mesoporous adsorbent

This study investigated the effectiveness of ionic liquids (ILs) loaded onto the surface of a polymeric adsorbent (βCD-TDI) grafted with modified magnetic nanoparticles (MNPs) via an analysis of water treatment, which resulted in high removal of selected endocrine-disrupting chemicals (parabens). The syntheses of MNPs, MNP-βCD-TDI, and IL-MNP-βCD-TDI were characterised and compared using Fourier transform infrared (FT-IR) spectroscopy, carbon-hydrogen-nitrogen (CHN) analysis, vibrating sample magnetometry (VSM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), the Brunauer-Emmett-Teller (BET) method, thermogravimetric analysis (TGA), and X-ray diffraction (XRD). The results of SEM and TEM indicated that the pore size distribution exhibited mesoporous characteristics with a small surface area (BET analysis: 42.95 m2 g-1). Furthermore, a preliminary sorption experiment demonstrated the ability of IL-MNP-βCD-TDI to enhance not only the sorption capacity, but also the removal of propyl paraben (PP), butyl paraben (BP), and benzyl paraben (ArP). The adsorption process appeared to be pH-dependent, and hence the optimum pH of 6 was selected for a subsequent batch adsorption study of all the studied parabens with an equilibrium time of 80 min. Next, in an attempt to investigate the interactions that occur between the adsorbent and the adsorbates, adsorption kinetics and isotherm studies were performed. All the studied parabens were found to best fit pseudo-second-order kinetics and the Freundlich isotherm with R 2 > 0.98 at room temperature (298 K). The interaction of the host-guest inclusion complex and the π-π interaction between βCD and a selected paraben compound (ArP) were identified by performing 1H nuclear magnetic resonance (NMR), together with ultraviolet-visible (UV-vis) spectroscopic analysis. Finally, the adsorption efficiency of the developed material was practically tested on tap water, drain water, and industrial wastewater, which revealed a significant removal of parabens of up to 60-90% in comparison with a prior analysis.

Cyclodextrin-Catalyzed Organic Synthesis: Reactions, Mechanisms, and Applications

Cyclodextrins are well-known macrocyclic oligosaccharides that consist of α-(1,4) linked glucose units and have been widely used as artificial enzymes, chiral separators, chemical sensors, and drug excipients, owing to their hydrophobic and chiral interiors. Due to their remarkable inclusion capabilities with small organic molecules, more recent interests focus on organic reactions catalyzed by cyclodextrins. This contribution outlines the current progress in cyclodextrin-catalyzed organic reactions. Particular emphases are given to the organic reaction mechanisms and their applications. In the end, the future directions of research in this field are proposed.

An ionic liquid loaded magnetically confined polymeric mesoporous adsorbent for extraction of parabens from environmental and cosmetic samples

Schematic illustration of MSPE procedure for paraben analysis using a new ionic liquid loaded magnetically confined polymeric mesoporous material.

β-Cyclodextrin based magnetic nanoconjugates for targeted drug delivery in cancer therapy

β-Cyclodextrin based magnetic nanoconjugates for targeted drug delivery.

Suzuki, Stille and Heck cross-coupling reactions catalyzed by Fe3O4@PTA–Pd as a recyclable and efficient nanocatalyst in green solvents

A novel heterogeneous Pd-catalyst was designed and successfully employed in C–C coupling reactions under green conditions.