Green synthesis and evaluation of antioxidant and antimicrobial activity of new dihydropyrroloazepines: Using bio‐Ag/CdO/ZnO@MWCNTs nanocomposites as a reusable organometallic catalyst

Unveiling the physicochemical, photocatalytic, antibacterial and antioxidant properties of MWCNT-modified Ag2O/CuO/ZnO nanocomposites

Water pollution, oxidative stress and the emergence of multidrug-resistant bacterial strains are significant global threats that require urgent attention to protect human health. Nanocomposites that combine multiple metal oxides with carbon-based materials have garnered significant attention due to their synergistic physicochemical properties and versatile applications in both environmental and biomedical fields. In this context, the present study was aimed at synthesizing a ternary metal-oxide nanocomposite consisting of silver oxide, copper oxide, and zinc oxide (ACZ-NC), along with a multi-walled carbon nanotubes modified ternary metal-oxide nanocomposite (MWCNTs@ACZ-NC). The properties of the synthesized nanomaterials were characterized using Fourier transform infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and energy dispersive X-ray (EDX) spectroscopy. The results obtained suggested the successful synthesis of both samples, as evidenced by the morphological changes observed in the SEM images, a transmittance band at 748.02 cm-1 in the FT-IR spectrum, and a diffraction peak at 44.39° in the XRD pattern. The band gap energies were determined via diffuse reflectance spectroscopy (DRS), with a redshift observed in the absorbance edge upon the incorporation of MWCNTs. The synthesized samples were tested as photocatalysts for the degradation of rhodamine 6G (Rh-6G), with the highest degradation efficiency (99.61%) achieved by MWCNTs@ACZ-NC. Additionally, the materials were evaluated for their biological activity as antibacterial and antioxidant agents. The MWCNTs@ACZ-NC exhibited the highest antioxidant potential with an IC50 value of 59.22 μg mL-1. However, the incorporation of MWCNTs resulted in a decrease in antibacterial activity, which may be attributed to the blocking of binding sites.

Novel Copper-Zinc-Manganese Ternary Metal Oxide Nanocomposite as Heterogeneous Catalyst for Glucose Sensor and Antibacterial Activity

A novel copper-zinc-manganese trimetal oxide nanocomposite was synthesized by the simple co-precipitation method for sensing glucose and methylene blue degradation. The absorption maximum was found by ultraviolet–visible spectroscopy (UV-Vis) analysis, and the bandgap was 4.32 eV. The formation of a bond between metal and oxygen was confirmed by Fourier Transform Infrared Spectroscopy (FT-IR) analysis. The average crystallite size was calculated as 17.31 nm by X-ray powder diffraction (XRD) analysis. The morphology was observed as spherical by scanning electron microscope (SEM) and high-resolution transmission electron microscopy (HR-TEM) analysis. The elemental composition was determined by Energy Dispersive X-ray Analysis (EDAX) analysis. The oxidation state of the metals present in the nanocomposites was confirmed by the X-ray photoelectron spectroscopy (XPS) analysis. The hydrodynamic diameter and zeta potential of the nanocomposite were 218 nm and −46.8 eV, respectively. The thermal stability of the nanocomposite was analyzed by thermogravimetry-differential scanning calorimetry (TG-DSC) analysis. The synthesized nanocomposite was evaluated for the electrochemical glucose sensor. The nanocomposite shows 87.47% of degradation ability against methylene blue dye at a 50 µM concentration. The trimetal oxide nanocomposite shows potent activity against Escherichia coli. In addition to that, the prepared nanocomposite shows strong antioxidant application where scavenging activity was observed to be 76.58 ± 0.30, 76.89 ± 0.44, 81.41 ± 30, 82.58 ± 0.32, and 84.36 ± 0.09 % at 31, 62, 125, 250, and 500 µg/mL, respectively. The results confirm the antioxidant potency of nanoparticles (NPs) was concentration dependent.

Acetylenic Esters in Organic Synthesis

Activated acetylenic substrates such as acetylenic esters and alkyl propiolates are very important in organic synthesis. Due to their electron deficiency, these compounds are widely used in combinatorial and multicomponent reactions, enabling the synthesis of a large variety of novel compounds. In addition, these substrates are powerful Michael acceptors and convenient dienophiles and dipolarophiles in Diels–Alder and 1,3-dipolar cycloaddition reactions. The addition of different nucleophiles, primarily phosphorus, nitrogen or sulfur, to the triple bonds of these substrates produces key intermediates, such as Tebby and Huisgen zwitterions, which can lead to designing pathways toward the generation of spirocyclic and polycyclic compounds. This account highlights recent studies on the chemistry of acetylenic esters and their applications in organic synthesis.

1 Introduction

2 Synthesis of Acyclic and Monocyclic Compounds

3 Synthesis of Spirocyclic Compounds

4 Synthesis of Polycyclic Compounds

5 Conclusion