Synthesis and characterization of nanostructured Cu-ZnO: An efficient catalyst for the preparation of (E)-3-styrylchromones

Synthesis, modifications, and applications of iron-based nanoparticles

Magnetic nanoparticles (MNPs) are appealing materials as assistant to resolve environmental pollution issues and as recyclable catalysts for the oxidative degradation of resistant contaminants. Moreover, they can significantly influence the advancement of medical applications for imaging, diagnostics, medication administration, and biosensing. On the other hand, due to unique features, excellent biocompatibility, high curie temperatures and low cytotoxicity of the Iron-based nanoparticles, they have received increasing attention in recent years. Using an external magnetic field, in which the ferrite magnetic nanoparticles (FMNPs) in the reaction mixtures can be easily removed, make them more efficient approach than the conventional method for separating the catalyst particles by centrifugation or filtration. Ferrite magnetic nanoparticles (FMNPs) provide various advantages in food processing, environmental issues, pharmaceutical industry, sample preparation, wastewater management, water purification, illness therapy, identification of disease, tissue engineering, and biosensor creation for healthcare monitoring. Modification of FMNPs with the proper functional groups and surface modification techniques play a significant role in boosting their capability. Due to flexibility of FMNPs in functionalization and synthesis, it is possible to make customized FMNPs that can be utilized in variety of applications. This review focuses on synthesis, modifications, and applications of Iron-based nanoparticles.

AlCl3@ZnO nanostructured material: an efficient green catalyst for the one-pot solvent-free synthesis of 1,4-dihydropyridines

AlCl3-loaded ZnO nanoparticles have been explored as an efficient catalyst for 1,4-dihydropyridine synthesis under ambient temperature and solvent-free conditions. For this purpose, ZnO nanoparticles were synthesized by a simple solution-based precipitation technique using a stoichiometric amount of zinc sulfate and oxalic acid. The AlCl3@ZnO nanocrystalline catalyst was prepared by loading 20% AlCl3 on ZnO nanoparticles by a simple wet-impregnation technique. This catalyst efficiently performed Hantzsch pyridine reactions with various aromatic aldehydes, ethyl acetoacetate and ammonium acetate. The nanostructured AlCl3-loaded ZnO catalyst was characterized by UV-DRS, XRD, FESEM, EDS, FETEM-STEM-EDS and XPS techniques. The comprehensive characterization reveals the formation of AlCl3-loaded ZnO catalysts with an average particle size of 70-80 nm. The loading of AlCl3 on the ZnO surface was confirmed by minor shifts in the XPS and XRD peaks. FETEM-STEM-EDS also indicates reasonable AlCl3 loading on ZnO nanoparticles. The 20% AlCl3-loaded ZnO nanocatalyst (AlCl3@ZnO) confers 92% yield for the synthesis of 1,4-dihydropyridine under solvent-free and ambient temperature conditions. The synthesized 1,4-dihydropyridines were characterized by 1H-NMR, 13C-NMR, HRMS and FT-IR spectroscopic techniques. The reported catalyst is highly efficient, environmentally friendly and could become an alternative to homogenous and heterogenous catalytic reactions.

Magnetically Recoverable Silica-Decorated Ferromagnetic-Nanoceria Nanocatalysts and Their Use with O- and N-Butyloxycarbonylation Reaction via Solvent-Free Condition

Silica-decorated ferrite nanoparticles, a new kind, coated with ceric ammonium nitrate (CAN), have been prepared successfully by simple coprecipitation techniques. Powder X-ray diffraction spectroscopy (PXRD), Fourier transform-infrared spectroscopy (FT-IR), field emission-scanning electron microscope (FE-SEM), wavelength-dispersive X-ray spectroscopy (WDX), energy-dispersive spectroscopy (EDS), inductive coupled plasma-optical emission spectroscopy (ICP-OES), and thermogravimetric analysis (TGA) techniques were used to characterize these nanoparticles. The catalysts are further studied for catalytic activity in solvent-free conditions. Importantly, these nanoparticles have been collected from the reaction mixture using an external magnet and recycled up to minimum of 15 cycles with no substantial loss of catalytic characteristics.

Effect of Cu Doping on ZnO Nanoparticles as a Photocatalyst for the Removal of Organic Wastewater

Environmental problems with chemical and biological water pollution have become a major concern for society. Providing people with safe and affordable water is a grand challenge of the 21st century. The study investigates the photocatalytic degradation capabilities of hydrothermally prepared pure and Cu-doped ZnO nanoparticles (NPs) for the elimination of dye pollutants. A simple, cost-effective hydrothermal process is employed to synthesize the Cu-doped ZnO NPs. The photocatalytic dye degradation activity of the synthesized Cu-doped ZnO NPs is tested by using methylene blue (MB) dye. In addition, the parameters that affect photodegradation efficiency, such as catalyst concentration, starting potential of hydrogen (pH), and dye concentration, were also assessed. The dye degradation is found to be directly proportional to the irradiation time, as 94% of the MB dye is degraded in 2 hrs. Similarly, the dye degradation shows an inverse relation to the MB dye concentration, as the degradation reduced from 94% to 20% when the MB concentration increases from 5 ppm to 80 ppm. The synthesized cost-effective and environmentally friendly Cu-doped ZnO NPs exhibit improved photocatalytic activity against MB dye and can therefore be employed in wastewater treatment materials.

Bio-synthesized Cu-ZnO hetro-nanostructure for catalytic degradation of organophosphate chlorpyrifos under solar illumination

In present study, a simple, effective and rapid green method using leaf extract of Melia azedarach was explored for the synthesis of Cu-ZnO nano heterojunction particles. The leaf extract of Melia azedarach acts as a reducing agent and prevents the agglomeration of nanoparticles. Different standard analytical techniques were used to study the morphology and size of synthesized nanocomposite. The efficiency of the synthesized material was tested as a photocatalyst for the degradation of simulated wastewater having chlorpyriphos pesticide. The different factors have been investigated such as pH of the solution, catalyst dosage and conact time. Approximately, 81% of chlorpyrifos was degraded after 240 min of solar illumination. The generation of hydroxyl radicals at the catalysts surface owing to photo-irradiation contributed to the chlorpyrifos degradation. The maximum photo-degradation (91%) of pesticides was observed at 6.0 pH. The pathway for the degradation of chlorpyriphos has been checked by LC-MS and this hinting the absence of any harmfull side product. The COD removal and TOC was found to be 32.4% and 28.5%, respectively. The photodegradation of chlorpyriphos using Cu-ZnO nanocomposite was followed the pseudo-first-order kinetic with higher value of regressiuon coefficient (0.99).

Photocatalytic, dye degradation, and bactericidal behavior of Cu-doped ZnO nanorods and their molecular docking analysis

Nanostructures of Cu-doped ZnO (Cu:ZnO) were prepared with the chemical precipitation technique with an aim to enhance the photocatalytic and antibacterial properties of ZnO. Phase constitution, the presence of functional groups, optical properties, elemental composition, surface morphology and microstructure were evaluated using an X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), UV-Vis spectrophotometer, energy dispersive X-ray spectroscopy (EDS), field emission scanning electron microscope (FESEM) and high resolution transmission electron microscope (HR-TEM), respectively. Emission spectra were obtained with a photoluminescence (PL) spectroscope whereas interlayer d-spacing was estimated through HR-TEM. ZnO consisted of a hexagonal wurtzite structure. The crystallinity of the sample was observed to increase with increasing doping concentration. The addition of Cu to ZnO served to transform nanoclusters into nanorods as revealed during SEM analysis. Catalytic activity enhanced due to the formation of nanorods, and UV-Vis absorption spectra showed that methylene blue (MB) degraded more efficiently with ZnO nanoclusters compared to the NaBH4 reagent. In addition, the doped NPs showed enhanced bacterial efficiency for G +ve. Finally, a molecular docking study was undertaken to highlight the importance of the binding interactions of the Cu-doped ZnO nanorods with β-lactamase and beta-ketoacyl-acyl carrier protein synthase III (FabH) as possible enzyme targets. This research indicates that Cu-doped Zn nanorods are a highly efficient photocatalyst and can be aptly employed for wastewater treatment and antibacterial applications.

Spectroscopic and computational study of chromone derivatives with antitumor activity: detailed DFT, QTAIM and docking investigations

Theoretical investigations of three pharmaceutically active chromone derivatives, (E)-3-((2,3,5,6-tetrafluorophenyl)hydrazono)methyl)-4H-chromen-4-one (TPC), (E)-3-((2-(2,4,6-trifluorophenyl)hydrazono)methyl)-4H-chromen-4-one (FHM) and(E)-3-((2-(perfluorophenyl)hydrazono)methyl)-4H-chromen-4-one (PFH) are reported. Molecular geometries, vibrational spectra, electronic properties and molecular electrostatic potential were investigated using density functional theory. Quantum theory of atoms in molecules (QTAIM) study shows that the maximum of ellipticity parameters in the existing bonds in TPC, FHM and PFH, attributes to the bonds involving in aromatic region points toward the π-bond interactions in the molecules. Based on energy gap (1.870, 1.649 and 1.590 eV) and electrophilicity index (20.233, 22.581 and 23.203 eV) values of TPC, FHM and PFH, we can conclude that all molecules have more biological activity. The molecular electrostatic potential maps were calculated to provide information on the chemical reactivity of the molecule and also to describe the intermolecular interactions. All these studies including docking studies, help a lot in determining the biological activities of chromone derivatives. Activities of chromone derivatives are compared with 5-fluorouracil and azathioprine (antitumor, antiproliferative standards) and were found to be higher than reference ones.

Nanostructured N doped TiO2 efficient stable catalyst for Kabachnik-Fields reaction under microwave irradiation

Herein, we report nitrogen-doped TiO₂ (N-TiO₂) solid-acid nanocatalysts with heterogeneous structure employed for the solvent-free synthesis of α-aminophosphonates through Kabachnik–Fields reaction. N-TiO₂ were synthesized by direct amination using triethylamine as a source of nitrogen at low temperature and optimized by varying the volume ratios of TiCl₄, methanol, water, and triethylamine, under identical conditions. An X-ray diffraction (XRD) study showed the formation of a rutile phase and the crystalline size is 10 nm. The nanostructural features of N-TiO₂ were examined by HR-TEM analysis, which showed they had rod-like morphology with a diameter of ∼7 to 10 nm. Diffuse reflectance spectra show the extended absorbance in the visible region with a narrowing in the band gap of 2.85 eV, and the high resolution XPS spectrum of the N 1s region confirmed successful doping of N in the TiO₂ lattice. More significantly, we found that as-synthesized N-TiO₂ showed significantly higher catalytic activity than commercially available TiO₂ for the synthesis of a novel series of α-amino phosphonates via Kabachnik–Fields reaction under microwave irradiation conditions. The improved catalytic activity is due to the presence of strong and Bronsted acid sites on a porous nanorod surface. This work signifies N-TiO₂ is an efficient stable catalyst for the synthesis of α-aminophosphonate derivatives.

Herein, we report nitrogen-doped TiO₂ (N-TiO₂) solid-acid nanocatalysts with heterogeneous structure employed for the solvent-free synthesis of α-aminophosphonates through Kabachnik–Fields reaction.

Iron Oxide-Cobalt Nanocatalyst for O-tert-Boc Protection and O-Arylation of Phenols

Efficient and general protocols for the O-tert-boc protection and O-arylation of phenols were developed in this paper using a recyclable magnetic Fe₃O₄-Co₃O₄ nanocatalyst (Nano-Fe-Co), which is easily accessible via simple wet impregnation techniques in aqueous mediums from inexpensive precursors. The results showed the catalysts were well characterized by XRD (X-ray Diffraction), ICP-AES (Inductive Coupled Plasma Atomic Emission Spectroscopy), TEM (Transmission Electron Microscopy), TOF-SIMS (Time-Of-Flight Secondary Ion Mass Spectrometry) and XPS (X-ray Photoelectron Spectroscopy). The O-tert-boc protection and O-arylation of phenols was accomplished in good to excellent yields (85–95%) and the catalyst was reusable and recyclable with no loss of catalytic activity for at least six repetitions.