Green synthesis of graphene oxide (GO)-anchored Pd/Cu bimetallic nanoparticles using Ocimum sanctum as bio-reductant: an efficient heterogeneous catalyst for the Sonogashira cross-coupling reaction

Pd@HKUST-1@Cu(II)/CMC composite bead as an efficient synergistic bimetallic catalyst for Sonogashira cross-coupling reactions

We fabricated an efficient Pd@HKUST-1@Cu(II)/CMC composite bead catalyst through an innovative strategy based on the unique properties of metal-organic frameworks (MOFs) and carboxymethylcellulose (CMC). In this strategy, HKUST-1 MOFs were grown in-situ on the surface of micrometer-sized Cu-based CMC beads (Cu(II)/CMC), then Pd(II) ions were incorporated into the pores of the MOF and further be partially reduced to Pd(0) NPs, which is an active species for oxidative addition with aryl halides in Sonogashira reactions. The micron-sized Cu(II)/CMC beads were formed through inter/intramolecularly crosslinking facilitated by Cu(II) ions, which was achieved by the metathesis of Cu(II) with numerous carboxylic groups of CMC. Such Cu(II)/CMC bead offers many Cu(II) ions as interaction sites for in-situ nucleation and growth of HKUST-1 MOFs. The architecture and composition of the prepared Pd@HKUST-1@Cu(II)/CMC composite were fully verified by various techniques such as FTIR, XRD, TGA, BET, XPS, SEM, TEM, EDX, and elemental mapping analysis. This novel composite bead was applied as an efficient and reusable heterogeneous Pd/Cu bimetallic catalyst for Sonogashira reactions, decarbonylative Sonogashira reaction, and Sonogashira cyclization tandem reactions. The catalyst is readily isolated by simple filtration, and can be reused for five consecutive runs with retaining its activity and structural integrity.

Synergistic performance of a new bimetallic complex supported on magnetic nanoparticles for Sonogashira and C-N coupling reactions

This paper describes the synthesis of a novel Cu-Ni bimetallic system comprising of magnetic nanoparticles, as the core, and 4-amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole (4-ABPT), as a conjugated bridge, between nickel and copper species. With low Cu and Ni loading (0.06 mol% Ni, 0.08 mol% Cu), the resulting Fe3O4@SiO2@4-ABPT/Cu-Ni showed to be a highly efficient catalyst for the Sonogashira and C-N cross-coupling reactions. The developed catalyst was well characterized by FT-IR, XRD, EDX-mapping, FE-SEM, TEM, ICP, VSM, TGA/DTG/DTA, LSV, and XPS techniques. Fe3O4@SiO2@4-ABPT/Cu-Ni nanocatalyst was compatible with a wide range of amines and aryl halides in the Sonogashira and C-N cross-coupling reactions and offered desired coupling products in high to excellent yields under palladium- and solvent-free conditions. Based on the XPS results, the 4-ABPT ligand can adjust electron transfer between Ni and Cu in Fe3O4@SiO2@4-ABPT/Cu-Ni, promoting the formation and stabilization of Cu+ and Ni3+ species. Electronic interactions and the synergistic effect between these metals increased the selectivity and activity of Fe3O4@SiO2@4-ABPT/Cu-Ni catalyst in the Sonogashira and C-N cross-coupling reactions compared with its monometallic counterparts. Additionally, the magnetic properties of Fe3O4@SiO2@4-ABPT/Cu-Ni facilitated its separation from the reaction mixture, promoting its reuse for several times with no significant loss in its catalytic activity or performance.

Metal–Organic Framework Derived Cobalt Oxide Supported Bimetallic Pd/Cu Nanoparticles for Efficient Catalysis of the Sonogashira Reaction under Aerobic Conditions

A bimetallic Pd/Cu catalyst supported on a metal-organic-framework-derived cobalt oxide was prepared and characterized by SEM, EDS, XRD, XPS, and ICP-OES analyses. The catalyst promoted the Sonogashira reaction of aryl iodides with terminal alkynes at a low loading of the palladium (0.032 mol%) and copper species (0.012 mol%) to give the corresponding disubstituted alkynes in moderate to good yields. When the catalyst was recovered by using an external magnetic field, its catalytic activity decreased slightly in a second cycle.

Preparation of In/Sn Nanoparticles (In3Sn and InSn4) by Wet Chemical One-Step Reduction and Performance Study

The preparation of binary alloys by surfactant-assisted chemical reduction in aqueous solution at room temperature has become a hot topic. In this article low melting point tin/indium (Sn/In) nanoparticles are synthesized. The formation process of the alloy was studied. Scanning electron microscopy, energy spectrometry, and X-ray diffraction are used to determine the morphology, composition, and crystal structure of the nanoparticles. Study found that fully alloyed indium-tin nanoparticles can be obtained by wet chemical method and the main phases of indium-tin alloy are β-phase (In3Sn) and γ-phase (InSn4). However, the Sn phase appears at a low content of indium (40 wt%). When the content of indium increases to 45 (wt%), the tin phase disappears. In addition, the most important finding is that the composition of the indium-tin alloy can be changed by ratio control, and the content of In3Sn increases with the increase of indium content. The relative content of In3Sn attains a maximum when the content of indium increases to 60 (wt%). In contrast, the content of InSn4 decreases. Finally, differential scanning calorimetry measurements is performed to understand the melting behavior of the nanoparticles and low melting temperatures are achieved for a wide range of indium compositions (from 40% to 60%). The melting temperature is found to be in the range of 125–132 °C and it increased with increasing In3Sn (also the increase of indium content). This gives us a new understanding into the binary alloy nano-system and gives important information for the application of low temperature alloy solders. The choice of composition can be based on the corresponding melting point.

Magnetic composite of γ-Fe2O3 hollow sphere and palladium doped nitrogen-rich mesoporous carbon as a recoverable catalyst for C-C coupling reactions

In this article, palladated-magnetic nitrogen doped porous carbon was prepared from nano magnetic γ-Fe2O3 hollow sphere (h-Fe2O3) with high specific surface area and pore volume. To the purpose, initially h-Fe2O3 was prepared and covered with glucose via hydrothermal treatment with subsequent polymerization of organic shell. The polymerization of melamine-resorcinol-formaldehyde (MRF) was achieved in the presence of Cl-functionalized glucose coated h-Fe2O3 (h-Fe2O3@glu-MRF). Next, the prepared magnetic core-shell hollow sphere was palladated followed by carbonization to yield Pd@h-Fe2O3@C introducing more pores in its structure. The resulted compound, Pd@h-Fe2O3@C, was fully characterized, showing that carbonization process expressively increased the specific surface area. The resulted Pd@h-Fe2O3@C was successfully used for promoting C-C coupling reactions under mild reaction conditions as a heterogeneous catalyst and its activity was compared with some prepared control catalysts. This novel catalyst was magnetically separated simply by a magnet bar and recycled and reused at least in five consecutive runs, without considerable loss of its activity. It is note mentioning that, high recyclability with low Pd leaching are another gains of this protocol.

Visible Light Response Photocatalytic Performance of Z-Scheme Ag3PO4/GO/UiO-66-NH2 Photocatalysts for the Levofloxacin Hydrochloride

A Ag₃PO₄/GO/UiO-66-NH₂(AGU) composite photocatalyst was prepared by an ultrasonic-assisted in situ precipitation method. The optical property, structure, composition, and morphology of photocatalysts were investigated using UV-vis diffuse reflectance spectroscopy, photoluminescence spectroscopy, electrochemical impedance spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, energy-dispersive spectrometry, transmission electron microscopy, Fourier transform infrared spectroscopy, and charge flow tracking by photodeposition of Pt and PbO₂ nanoparticles. In comparison with Ag₃PO₄ and Ag₃PO₄/UiO-66-NH₂(AU), the AGU composite photocatalyst showed heightened photocatalytic performance for the degradation of levofloxacin hydrochloride (LVF). The AGU photocatalyst (dosage: 0.8 g/L) with 1% mass content of graphene oxide (GO), the mass ratio of Ag₃PO₄ and UiO-66-NH₂(U66N) reached 2:1, showed the highest photodegradation rate of 94.97% for 25 mg/L LVF after 60 min of visible light irradiation at pH = 6. The formation of a heterojunction and the addition of GO synergistically promote faster separation of electron-hole pairs, retain more active substances, and enhance the performance of the photocatalyst. Furthermore, the mechanism of the Z-scheme of the AGU composite photocatalytic is proposed.

Recent Progress of Metal Nanoparticle Catalysts for C–C Bond Forming Reactions

Over the past few decades, the use of transition metal nanoparticles (NPs) in catalysis has attracted much attention and their use in C–C bond forming reactions constitutes one of their most important applications. A huge variety of metal NPs, which have showed high catalytic activity for C–C bond forming reactions, have been developed up to now. Many kinds of stabilizers, such as inorganic materials, magnetically recoverable materials, porous materials, organic–inorganic composites, carbon materials, polymers, and surfactants have been utilized to develop metal NPs catalysts. This review classified and outlined the categories of metal NPs by the type of support.

Biogenic synthesis of bimetallic nanoparticles and their applications

The current advancements in nanotechnology suggest a sustainable development in the green synthesis of bimetallic nanoparticles (BMNPs) through green approaches. Though challenging, nano phyto technology has versatile methods to achieve desired unique properties like optic, electronic, magnetic, therapeutic, and catalytic efficiencies. Bio-inspired, facile synthesis of bifunctional BMNPs is possible using abundant, readily available natural plant sources, bio-mass wastes and microorganisms. Synergistic effects of two different metals on mixing, bring new insight for the vast applications, which is not achievable in using monometallic NPs. By adopting bio-inspired greener approaches for synthesizing NPs, the risk of environmental toxicity caused by conventional physicochemical methods become negligible. This article hopes to provide the significance of cost-effective, one-step, eco-friendly and facile synthesis of noble/transition bimetallic NPs. This review article endows an overview of the bio-mediated synthesis of bimetallic NPs, classifications of BMNPs, current characterization techniques, possible mechanistic aspects for reducing metal ions, and the stability of formed NPs and bio-medical/industrial applications of fabricated NPs. The review also highlights the prospective future direction to improve reliability, reproducibility of biosynthesis methods, its actual mechanism in research works and extensive application of biogenic bimetallic NPs.

Recent advances in the development of palladium nanocatalysts for sustainable organic transformations

In this review, we highlighted Pd nanocatalysts which have been used in the development of sustainable organic transformations including transfer hydrogenation, C–H bond activation, and some carbon–carbon couplings in the last five years.