Electronic properties and adsorption mechanism of Ru-doped copper clusters towards CH3OH molecule: A DFT investigation

In this study, we have investigated the stability and electronic properties of the Cu_nRu (n = 2-10) nanoclusters and their interaction with the CH₃OH molecule without and with the presence of O₂ molecule by using DFT calculations with TPSS/SDD/6-311g(d,p) level of theory. Based on the second energy difference (Δ²E), the results reveal that the Cu_nRu (n = 4, 6 and 8) clusters are relatively more stable than their neighboring clusters. The values obtained for the Fukui function (f^-) proves that the Ru atom in the Cu_nRu clusters is an excellent adsorption site for the molecules. The interaction of the Cu_nRu clusters with CH₃OH molecule exhibits that the Ru atom is the preferred adsorption site for the CH₃OH molecule, where the O atom of the CH₃OH molecule is strongly chemisorbed onto the Ru site of the clusters, forming a strong bond between the Ru and O atoms. The copper sites of the clusters were found less preferred for the adsorption of CH₃OH, and the complexes formed between both species are less stable than those obtained from the CH₃OH chemisorption over the Ru site of the clusters. The interaction of CH₃OH with the clusters was also evaluated in an oxidizing environment, and the results obtained reveal that the molecule is greatly chemisorbed over the ruthenium site with adsorption energies which vary from - 1.18 to - 2.05 eV. In the presence of the oxygen, the gap energy of the clusters was sharply changed after their interactions with the CH₃OH molecule, suggesting that these clusters can easily detect the above molecule with great sensitivity. Therefore, the presence of the oxygen not only does not prevent the adsorption process, but it considerably promotes the CH₃OH chemisorption onto the ruthenium site of the clusters and therefore significantly rises their sensitivity performance. In conclusion, the Cu_nRu clusters could be employed as effective nanosensors for the CH₃OH molecule detection.

Water Saturated with Pressurized CO2 as a Tool to Create Various 3D Morphologies of Composites Based on Chitosan and Copper Nanoparticles

Methods for creating various 3D morphologies of composites based on chitosan and copper nanoparticles stabilized by it in carbonic acid solutions formed under high pressure of saturating CO2 were developed. This work includes a comprehensive analysis of the regularities of copper nanoparticles stabilization and reduction with chitosan, studied by IR and UV-vis spectroscopies, XPS, TEM and rheology. Chitosan can partially reduce Cu2+ ions in aqueous solutions to small-sized, spherical copper nanoparticles with a low degree of polydispersity; the process is accompanied by the formation of an elastic polymer hydrogel. The resulting composites demonstrate antimicrobial activity against both fungi and bacteria. Exposing the hydrogels to the mixture of He or H2 gases and CO2 fluid under high pressure makes it possible to increase the porosity of hydrogels significantly, as well as decrease their pore size. Composite capsules show sufficient resistance to various conditions and reusable catalytic activity in the reduction of nitrobenzene to aniline reaction. The relative simplicity of the proposed method and at the same time its profound advantages (such as environmental friendliness, extra purity) indicate an interesting role of this study for various applications of materials based on chitosan and metals.

Enhanced reduction of nitrobenzene derivatives using reusable Ni nanoparticles supported on multi-layered poly(1,2-phenylenediamine)-coated layered double hydroxides

Recently, nanomaterials with layered double hydroxide (LDH) cores have been the subject of intense research regarding their promising applications in organic synthesis. In this study, nitrobenzene reduction is investigated by designing and synthesizing a novel LDH-based heterogeneous catalyst containing a nickel-1,2-phenylenediamine complex. The Cu–Zn–Al LDH was functionalized with copolymer bearing a glycidyl methacrylate (GMA) linkage that makes it suitable for grafting with 1,2-phenylenediamine. Overall, the synthesized LDH@MPS-GMA-PDA-Ni was found to be a highly efficient heterogeneous nanocatalyst that can catalyze nitroarene reduction with high yields under mild conditions.

Highly porous copper-supported magnetic nanocatalysts: made of volcanic pumice textured by cellulose and applied for the reduction of nitrobenzene derivatives

Herein, a novel designed heterogeneous catalytic system constructed of volcanic pumice magnetic particles (VPMPs), cellulose (CLS) as a natural polymeric matrix, and copper nanoparticles (Cu NPs) is presented. Also, to enhance the inherent magnetic property of VPMP, iron oxide (Fe3O4) nanoparticles have been prepared and incorporated in the structure via an in situ process. As its first and foremost excellent property, the designed composite is in great accordance with green chemistry principles because it contains natural ingredients. Another brilliant point in the architecture of the designed composite is the noticeable porosity of VPMP as the core of the composite structure (surface area: 84.473 m2 g-1). This great porosity leads to the use of a small amount (0.05 g) of the particles for catalytic purposes. However, the main characterization methods, such as Fourier-transform infrared and energy-dispersive X-ray spectroscopy, thermogravimetric analysis, and electron microscopy, revealed that the spherical metallic particles (Fe and Cu oxides) were successfully distributed onto the surface of the VPMP and CLS matrices. Further, vibrating-sample magnetometer analysis confirmed the enhancement of the magnetic property (1.5 emu g-1) of the composite through the addition of Fe3O4 nanoparticles. Further, the prepared (Fe3O4@VPMP/CLS-Cu) nanocomposite has been applied to facilitate the reduction reaction of hazardous nitrobenzene derivatives (NBDs) to their aniline analogs, with 98% conversion efficiency in eight minutes under mild conditions. Moreover, the good reusability of the catalytic system has been verified after recycling it ten times without any significant decrease in the performance.

Plant-Based Biosynthesis of Copper/Copper Oxide Nanoparticles: An Update on Their Applications in Biomedicine, Mechanisms, and Toxicity

Plants are rich in phytoconstituent biomolecules that served as a good source of medicine. More recently, they have been employed in synthesizing metal/metal oxide nanoparticles (NPs) due to their capping and reducing properties. This green synthesis approach is environmentally friendly and allows the production of the desired NPs in different sizes and shapes by manipulating parameters during the synthesis process. The most commonly used metals and oxides are gold (Au), silver (Ag), and copper (Cu). Among these, Cu is a relatively low-cost metal that is more cost-effective than Au and Ag. In this review, we present an overview and current update of plant-mediated Cu/copper oxide (CuO) NPs, including their synthesis, medicinal applications, and mechanisms. Furthermore, the toxic effects of these NPs and their efficacy compared to commercial NPs are reviewed. This review provides an insight into the potential of developing plant-based Cu/CuO NPs as a therapeutic agent for various diseases in the future.

Cu/CuO Composite Track-Etched Membranes for Catalytic Decomposition of Nitrophenols and Removal of As(III)

One of the promising applications of nanomaterials is to use them as catalysts and sorbents to remove toxic pollutants such as nitroaromatic compounds and heavy metal ions for environmental protection. This work reports the synthesis of Cu/CuO-deposited composite track-etched membranes through low-temperature annealing and their application in catalysis and sorption. The synthesized Cu/CuO/poly(ethylene terephthalate) (PET) composites presented efficient catalytic activity with high conversion yield in the reduction of nitro aryl compounds to their corresponding amino derivatives. It has been found that increasing the time of annealing raises the ratio of the copper(II) oxide (CuO) tenorite phase in the structure, which leads to a significant increase in the catalytic activity of the composites. The samples presented maximum catalytic activity after 5 h of annealing, where the ratio of CuO phase and the degree of crystallinity were 64.3% and 62.7%, respectively. The catalytic activity of pristine and annealed composites was tested in the reduction of 4-nitroaniline and was shown to remain practically unchanged for five consecutive test cycles. Composites annealed at 140 °C were also tested for their capacity to absorb arsenic(III) ions in cross-flow mode. It was observed that the sorption capacity of composite membranes increased by 48.7% compared to the pristine sample and reached its maximum after 10 h of annealing, then gradually decreased by 24% with further annealing.

The di(thiourea)gold(I) complex [Au{S=C(NH2)2}2][SO3Me] as a precursor for the convenient preparation of gold nanoparticles

The synthesis of [Au{S=C(NH2)2}2][SO3Me] (1) (a) by the anodic oxidation of gold metal in an anolyte of thiourea and methansulfonic acid and (b) by the reaction of Au(OH)3 with an aqueous solution of methanesulfonic acid in the presence of thiourea is reported. The structure of 1 in the solid state has been determined by single-crystal X-ray diffraction showing a linear S–Au–S unit with the thiourea ligands in a leaflet structure folded by 113.2(3)°. The cation of complex 1 is a dimer, based on short S · · · C interactions between two adjacent mononuclear cations. The thermal decomposition behavior of 1 was studied by TG and TG-MS confirming that it decomposes under inert gas or oxygen atmosphere in four steps in the temperature range of 200–650°C. Initial decomposition starts with the release and fragmentation of one of the thiourea ligands, followed by the anion degradation. Powder X-ray diffraction studies specified the formation of gold metal. Based on this observation, complex 1 was used as precursor for the formation of gold nanoparticles (Au NPs) in 1-hexadecylamine (c = 4.0 mol L−1) at T = 330°C without any addition of reducing agents. TEM, electron diffraction, and UV/Vis spectroscopy studies were carried out. Au NPs of size 15 ± 4 nm were formed, showing the characteristic surface plasmon resonance at 528 nm.

Glycerol: An Optimal Hydrogen Source for Microwave-Promoted Cu-Catalyzed Transfer Hydrogenation of Nitrobenzene to Aniline

The search for sustainable alternatives for use in chemical synthesis and catalysis has found an ally in non-conventional energy sources and widely available green solvents. The use of glycerol, an abundant natural solvent, as an excellent “sacrificial” hydrogen source for the copper-catalyzed microwave (MW)-promoted transfer hydrogenation of nitrobenzene to aniline has been investigated in this work. Copper nanoparticles (CuNPs) were prepared in glycerol and the efficacy of the glycerol layer in mediating the interaction between the metal active sites has been examined using HRTEM analyses. Its high polarity, low vapor pressure, long relaxation time, and high acoustic impedance mean that excellent results were also obtained when the reaction media was subjected to ultrasound (US) and MW irradiation. US has been shown to play an important role in the process via its ability to enhance CuNPs dispersion, favor mechanical depassivation and increase catalytic active surface area, while MW irradiation shortened the reaction time from some hours to a few minutes. These synergistic combinations promoted the exhaustive reduction of nitrobenzene to aniline and facilitated the scale-up of the protocol for its optimized use in industrial MW reactors.

Synthesis and characterization of a novel TEMPO@FeNi3/DFNS–laccase magnetic nanocomposite for the reduction of nitro compounds

Water is an essential substance for life on earth and for all living things. Plants and animals need almost pure water to live; if it is contaminated with harmful chemicals and micro organisms, it will be impossible for them to survive. This study has tried to investigate the performance of catalyst to reduce nitro-aromatic combinations in the attendance of NaBH₄ solution duo to the hydrogen source. TEMPO@FeNi₃/DFNS–laccase MNPs was prepared, and its features were reviewed using SEM, TEM, XRD, TGA, VSM, AFM, and FTIR. Then, its strength as a nanocatalyst for removal of nitro-aromatic combinations was tested in contact time, initial concentration, the effects of pH and nanocatalyst amount was study. The results of this research proved that TEMPO@FeNi₃/DFNS–laccase MNPs has a good return in removal of nitro-aromatic combinations, as its easy synthesis and reliable recovery.

Water is an essential substance for life on earth and for all living things.

Michael Addition Reaction Catalyzed by Imidazolium Chloride to Protect Amino Groups and Construct Medium Ring Heterocycles

An effective approach for amino protection and construction of a seven-membered ring has been developed. The method uses imidazolium chloride to carry out the Michael addition reaction at low temperatures and perform amino deprotection or construction of a seven-membered ring at high temperatures.

Phytosynthesis of Cu/rGO using Euphorbia cheiradenia Boiss extract and study of its ability in the reduction of organic dyes and 4-nitrophenol in aqueous medium

For the first time, copper nanoparticles (Cu NPs) superficially deposited on reduced graphene oxide (rGO) using Euphorbia cheiradenia Boiss leaf aqueous media. A beneficial series of analytical methods was used to characterise E. cheiradenia Boiss leaf extract and involved nanostructures. The Cu/rGO nanocomposite (NC) obtained from the conversion of Cu²⁺ ions to Cu NPs and GO to rGO undergoes the plant extract and used as a heterogeneous and reusable nanocatalyst for the destruction of 4-nitrophenol, rhodamine B, methylene blue, methyl orange and congo red using sodium borohydride at ambient temperature. In addition, Cu/rGO NC has reusability for many times in the reduction reactions with no decreasing of its catalytic capability.

Electron Beam Induced Enhancement of the Catalytic Properties of Ion-Track Membranes Supported Copper Nanotubes in the Reaction of the P-Nitrophenol Reduction

This study considers the effect of various doses of electron irradiation on the crystal structure and properties of composite catalysts based on polyethylene terephthalate track-etched membranes and copper nanotubes. Copper nanotubes were obtained by electroless template synthesis and irradiated with electrons with 3.8 MeV energy in the dose range of 100–250 kGy in increments of 50 kGy. The original and irradiated samples of composites were investigated by X-ray diffraction technique (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The improved catalytic activity of composite membranes with copper nanotubes was demonstrated by the example of the reduction reaction of p-nitrophenol in the presence of sodium borohydride. Irradiation with electrons at doses of 100 and 150 kGy led to reaction rate constant increases by 35 and 59%, respectively, compared to the non-irradiated sample. This enhancing catalytic activity could be attributed to the changing of the crystallite size of copper, as well as the surface roughness of the composite membrane.

Facile synthesis of palladium nanoparticles immobilized on magnetic biodegradable microcapsules used as effective and recyclable catalyst in Suzuki-Miyaura reaction and p-nitrophenol reduction

This study reports (i) preparation and characterization of palladium nanoparticles (Pd NPs) stabilized on magnetically separable chitosan/agar microcapsules (Pd NPs@Fe₃O₄/CS-AG microcapsules) and (ii) investigation of catalytic behaviors of the prepared nanoparticles in Suzuki-Miyaura C-C cross-coupling reactions and reduction of p-nitrophenol (p-NP). Fourier transforms infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD), elemental mapping, inductively coupled plasma-optical emission spectrometry (ICP-OES) and thermogravimetry/derivative thermogravimetry (TG/DTG) techniques were used for analyzing the Pd NPs@Fe₃O₄/CS-AG microcapsules. Characterization studies showed that Pd NPs@Fe₃O₄/CS-AG microcapsules were successfully synthesized and the size of the particles was in the range of 28-39 nm. Pd NPs@Fe₃O₄/CS-AG microcapsules displayed highly effective catalytic performance in the conversion of various aryl halides into the corresponding biaryl derivatives by Suzuki-Miyaura reaction under solvent-free conditions in 5 min. Pd NPs@Fe₃O₄/CS-AG microcapsules were also successfully employed in p-NP reduction to p-aminophenol (p-AP) in water at room temperature in 180 s. Moreover, reproducibility studies showed that Pd NPs@Fe₃O₄/CS-AG microcapsules were highly efficient and could be used many times in both catalytic reactions due to their magnetically separable nature. According to the results of this work, Pd NPs@Fe₃O₄/CS-AG microcapsules are highly efficient, economical, practical and environmentally superb catalysts for Suzuki-Miyaura reaction and p-NP reduction.

Flower-like 3-dimensional hierarchical Co3O4/NiO microspheres for 4-nitrophenol reduction reaction

Aromatic nitro compounds are toxic and not biodegradable. Therefore, the elimination of nitro groups is very important. Metal catalysts play an important role in the catalytic transformation. We present here flower-like 3D hierarchical Co₃O₄/NiO microspheres, which are prepared by a chemical precipitation method. The as-prepared catalyst is characterized by FTIR, SEM, TEM, EDS, XRD, XPS and N₂ sorption isotherms. They have shown different morphologies such as flower, nanocubes, and hexagonal structure at different calcined temperatures. The synthesized catalyst is tested and used for the reduction of 4-nitrophenol to 4-aminophenol in the presence of sodium borohydride as a reducing agent. The reaction takes place in an aqueous medium at room temperature. The bimetallic catalyst Co₃O₄/NiO showed good performance and reusability.

Synergistic effect of bimetallic Cu:Ni nanoparticles for the efficient catalytic conversion of 4-nitrophenol

A non-noble metal-based bimetallic Cu–Ni system for the conversion of 4-nitrophenol and effective recyclability by magnetic retrieval of the catalyst.

Highly active copper catalyst obtained through rapid MOF decomposition

A decomposed copper based metal–organic framework containing amorphous Cu species was found to be a highly reactive carbon supported catalyst (a-Cu@C).

Surprisingly high sensitivity of copper nanoparticles toward coordinating ligands: consequences for the hydride reduction of benzaldehyde

Depending on the ligand, ligand-induced leaching of copper nanoparticles may produce catalytically active species for the reduction of benzaldehyde.