Natrolite zeolite supported copper nanoparticles as an efficient heterogeneous catalyst for the 1,3-diploar cycloaddition and cyanation of aryl iodides under ligand-free conditions

Reversible Cu-Nanoparticle Formation in Soft Hydrogel Composites: Towards Write-Erase Displays and Fluorescence Detection

In this study, we introduce a hydrogel-polymer microsphere (HPM) composite material constituted of PVA, glycerin, and polymer microspheres obtained from Pickering emulsions that are capable of adsorbing Cu2+ ions. The obtained HPM composite is soft, flexible, can be fully saturated with Cu2+ ions, and exhibits a reversible color transition from blue to black upon electrode contact or interaction with a reducing agent, due to in situ generation of copper nanoparticles (Cu-NPs). Because of the color contrast between the locally generated Cu-NPs and the background, the HPM can be used as substrate for stamping different shapes or writing text. Further, the surface can be erased by an acidic solution, which makes it interesting as flexible write-erase displays. A second feature of the HPM is that it can function as a fluorescence detector of cyanide ions. An HPM whose surface has been stamped with an electrode, upon contacting an aqueous solution containing cyanide ions, begins fluorescing a yellow-green light around the patterned area. The displayed luminescence is irreversible and is preserved even after HPM's drying or lyophilization. This work lays a foundational framework for future exploration of the HPM composites in various technological applications, for sensing, circuit printing, and flexible displays.

Magnetically separable triazine-based Cu(ii)-vitamin B5 complex in nitromethane toward efficient heterogeneous cyanation reaction of aryl halides

In the current study, a highly efficient heterogeneous copper catalyst has been developed by supporting copper acetate on a magnetically separable triazine-vitamin B₅ system. After the successful characterization of the prepared nanoparticles by various techniques such as FT-IR, FE-SEM, EDX/MAP, XRD, TEM, TGA, VSM, and ICP-OES, the catalytic efficiency of them were evaluated in the cyanation reaction of aryl halides in the presence of nitromethane as a non-toxic and cost-effective cyanation source. The cyanation products were obtained in desirable yields. Notably, the magnetic nanocatalyst can be easily recovered and reused at least five times without a significant decrease in its performance.

Greener synthesis of 1,2,3-triazoles using a copper(i)-exchanged magnetically recoverable β-zeolite as catalyst

A novel magnetically recoverable Cu(i)-exchanged β-zeolite catalyst was prepared, characterized and applied for the synthesis of 1,2,3-triazoles via the one-pot three-component reaction.

Non-toxic cyanide sources and cyanating agents

The present review gives an overview over non-toxic cyanation agents and cyanide sources used in the synthesis of structurally diverse products containing the nitrile function. Nucleophilic as well as electrophilic agents/systems that transfer the entire CN-group were taken in consideration. Reactions in which a preexisting carbon functionality is transformed into a nitrile function by addition of nitrogen are however not covered here.

Diaryl ethers synthesis: nano-catalysts in carbon-oxygen cross-coupling reactions

The diaryl ether moiety is not only prevalent in a significant number of natural products and synthetic pharmaceuticals but also widely found in many pesticides, polymers, and ligands. Ullmann-type cross-coupling reactions between phenols and aryl halides are regarded as one of the most important methods for the synthesis of this important and versatile structural motif. In recent years, the use of nano-sized metal catalysts in this coupling reaction has attracted a lot of attention because of these catalysts with their high surface-to-volume ratio, high surface energy, and reactive morphology allows for rapid C-O bond formation under mild and ligand-free conditions. In this review we will highlight the power of these catalysts in Ullmann-type C-O cross-coupling reactions.

Synthesis paradigm and applications of silver nanoparticles (AgNPs), a review

Nanoscience is an inspiring and influential discipline of science which have accessible numerous novel and cost-effective yields and applications. Currently, nanotechnology research has been empowering more in agricultural sector, food process and medicinal industries. The surface area to volume ratio of nanoparticles is quite large which have 1–100 nm size. Nanomaterials have superior bioavailability than larger particles, resulting in greater utilization in single cells, tissues and organs. Referable to the growing demand of nanoparticles, it is essential to build up synthetic method which is profitable, environmentally sustainable and which can substitutes with effective and competent technology to synthesis environmentally benign nanoparticles (NPs). Nanomaterials are “deliberately engineered” to direct the enhancement of special properties at the nanoscale. Nanoparticles have been known to be used for abundant physical, biological, and pharmaceutical applications. Nano-silver is the most studied and utilized nanoparticle. Silver nanoparticles (AgNPs) have been the topics of researchers because of their unique properties. Thus, this review presents various synthesis methods of AgNPs and its application in different sectors.

Visible light photo catalytic inactivation of bacteria and photo degradation of methylene blue with Ag/TiO2 nanocomposite prepared by a novel method

Water purification is one of the worldwide problem and most of the conventional methods are associated with a number of drawbacks. Therefore it is the need of the day to develop new methods and materials to overcome the problem of water purification. In this research work we present a simple and green approach to synthesize silver decorated titanium dioxide (Ag/TiO2) nanocomposite with an efficient photo catalytic activities. Phytochemicals of the Cestrum nocturnum leaf extract were used to synthesize silver nanoparticles (AgNPs), Titanium dioxide (TiO2) and Ag/TiO2 nanocomposite. To confirm the formation, crystal structure, particle size and shape of green synthesized nanoparticles and nanocomposite, they were characterized by UV-visible spectroscopy (UV-vis), X-ray diffraction spectroscopy (XRD), high resolution transmission electron microscopy (HRTEM), Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). The AgNPs, TiO2 and Ag/TiO2 were evaluated for photo degradation of methylene blue (MB) and photo inhibition of Bacteria. The bio-synthesized Ag/TiO2 nanocomposite was observed to have strong catalytic activities for photo reduction of MB and photo inactivation of bacteria as compared to bare AgNPs and TiO2. In the presence of Ag/TiO2, 90% of MB was degraded only in 40min of irradiation. Alternatively the bare AgNPs and TiO2 degraded less than 30% and 80% respectively of MB even in more than 100min of irradiation. Similarly the Ag/TiO2 has very strong photo inhibition efficiency towards Escherichia coli and Pseudomonas aeruginosa. The zone of inhibition of irradiated Ag/TiO2 nanocomposites against E. coli and P. aeruginosa was 19mm and 17mm respectively which was two times higher than in dark. These promising photocatalytic activities of nanocomposite may be due to the highly decorated AgNPs over the surface of TiO2.

Biosynthesis, characterization and catalytic activity of an Ag/zeolite nanocomposite for base- and ligand-free oxidative hydroxylation of phenylboronic acid and reduction of a variety of dyes at room temperature

A green synthesis of an Ag/zeolite nanocomposite and its catalytic activity were investigated. Its catalytic efficiency remains unaltered even after several repeated cycles.

Preparation of Pd/Fe3O4 nanoparticles by use of Euphorbia stracheyi Boiss root extract: A magnetically recoverable catalyst for one-pot reductive amination of aldehydes at room temperature

We describe a method for supporting palladium nanoparticles on magnetic nanoparticles using Euphorbia stracheyi Boiss root extract as the natural source of reducing and stabilizing agent. The progress of the reaction was monitored using UV-visible spectroscopy. The nanocatalyst was characterized by FE-SEM, TEM, XRD, EDS, FT-IR spectroscopy and ICP. The nanocatalyst was applied as an efficient, magnetically recoverable, highly reusable and heterogeneous catalyst for one-pot reductive amination of aldehydes at room temperature. The nanocatalyst was easily recovered by applying an external magnet and reused several times without considerable loss of activity.

Pd nanoparticles synthesized in situ with the use of Euphorbia granulate leaf extract: Catalytic properties of the resulting particles

For the first time the extract of the plant of Euphorbia granulate was used to green synthesis of Pd nanoparticles (NPs) as a heterogeneous catalyst for the phosphine-free Suzuki-Miyaura coupling reaction at room temperature. This method is a facile and eco-friendly way in organic synthesis using the plant extract as biomedia, bioreductant and capping ligand which considerably stabilizes the surface of Pd NPs. The presence of flavonoid and phenolics acids in the extract could be responsible for the reduction of Pd(2+) ions and formation of the corresponding Pd NPs.

CuCO3–CuO nanocomposite as a novel and environmentally friendly catalyst for triazole synthesis

This paper focuses on the use of natural sources for the preparation of efficient and low cost catalysts for triazole synthesis.

Green synthesis, characterization and catalytic activity of natural bentonite-supported copper nanoparticles for the solvent-free synthesis of 1-substituted 1H-1,2,3,4-tetrazoles and reduction of 4-nitrophenol

In this study, Cu nanoparticles were immobilized on the surface of natural bentonite using Thymus vulgaris extract as a reducing and stabilizing agent. The natural bentonite-supported copper nanoparticles (Cu NPs/bentonite) were characterized by FTIR spectroscopy, X-ray diffraction (XRD), X-ray fluorescence (XRF), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and Brunauer-Emmett-Teller (BET) analysis. Afterward, the catalytic performance of the prepared catalyst was investigated for the solvent-free synthesis of 1-substituted 1H -1,2,3,4-tetrazoles and reduction of 4-nitrophenol (4-NP) in water. It was found that the Cu NPs/bentonite is a highly active and recyclable catalyst for related reactions.