Amine-Functionalized Graphene Oxide-Stabilized Pd Nanoparticles (Pd@APGO): A Novel and Efficient Catalyst for the Suzuki and Carbonylative Suzuki-Miyaura Coupling Reactions

Carbonylative Self-Coupling of Aryl Boronic Acids Using a Confined Pd Catalyst within Melamine Dendron and Fibrous Nano-Silica: A CO Surrogate Approach

Development of heterogeneous catalysts with tunable activity and selectivity has posed a persistent challenge. This study addresses this challenge by fabricating a hybrid environment through the combination of mesoporous silica and N-rich melamine dendron via covalent grafting, allowing for controllable growth and encapsulation of Pd NPs. This catalyst presented an excellent catalytic activity for the oxidative carbonylative self-coupling of aryl boronic acids to afford symmetric biaryl ketones using N-formyl saccharin as a sustainable solid CO source and Cu as a co-catalyst.

Amine-functionalized reduced graphene oxide-supported silver nanoparticles for superior catalytic reduction of organic pollutants

In this work, a simple and environmentally friendly approach has been followed to synthesize amine-functionalized reduced graphene oxide (RGO)-supported silver nanoparticle (AgNPs) having superior catalytic efficiency towards the reduction of organic pollutants. RGO/AgNPs nanohybrid was synthesized by a one-pot hydrothermal reduction of silver nitrate in the presence of amino-propyl trimethoxy silane (APTMS)-functionalized graphene oxide (GO) nanosheets. The structural and morphological characterization of as-synthesized RGO/AgNPs nanohybrid was done by using XRD, SEM, TEM, FT-IR, and Raman spectroscopy techniques. APTMS plays an important role in controlling the size of anchored AgNPs on the nanohybrid in the present study. The -NH2 groups on the surface of APTMS-modified GO function as effective and well-organized nucleation centers facilitating uniform growth of discrete and smaller-sized spherical AgNPs on the surface of RGO nanosheets. In the absence of APTMS, the nanohybrid comprised of bigger-sized AgNPs with few hundred of nanometers in dimension. The catalytic efficiency of RGO/AgNPs nanohybrid was evaluated for the reduction of two model organic pollutants: 4-nitrophenol (4-NP) and methylene blue (MB). Due to the synergistic effects of RGO, APTMS, and Ag components, RGO/AgNPs nanohybrid developed in the present study exhibited superior catalytic activity towards the reduction of 4-NP and MB in comparison with previously reported graphene/graphene oxide/reduced graphene oxide-supported AgNPs catalysts. The catalytic reduction of 4-NP and MB followed pseudo-unimolecular kinetics and the rate constants were found to be 18.83 × 10-3 s-1 and 131.5 ×10-3 s-1 respectively for 4-NP and MB. Furthermore, RGO/AgNPs nanohybrid showed admirable recyclability with negligible loss in its activity until five recycle runs. The superior catalytic activity, favorable kinetic parameters, and sustained catalytic efficiency after recycling make RGO/AgNPs nanohybrid a promising catalyst for the reduction of organic pollutants in environmental remediation.

Highly Enantioselective Binaphthyl-Based Chiral Phosphoramidite Stabilized-Palladium Nanoparticles for Asymmetric Suzuki C-C Coupling Reactions

The optically pure binaphthyl-based phosphoramidite ligands and their perfluorinated analogs have been first used for the preparation of chiral palladium nanoparticles (PdNPs). These PdNPs have been extensively characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, ³¹P NMR, and thermogravimetric analysis techniques. The circular dichroism(CD) analysis of chiral PdNPs exhibited negative cotton effects. Perfluorinated phosphoramidite ligands provided smaller (2.32-3.45 nm) and well-defined nanoparticles, in comparison with the nonfluorinated analog (4.12 nm). The catalytic behavior of binaphthyl-based phosphoramidite stabilized chiral PdNPs has been investigated in the asymmetric Suzuki C-C coupling reactions for the formation of sterically hindered binaphthalene units, and high isolated yields (up to 85%) were achieved with excellent enantiomeric excesses (>99% ee). Recycling studies revealed that chiral PdNPs could be reused over 12 times without significant loss in activity and enantioselectivity (>99% ee). The nature of the active species was also investigated with a combination of poisoning and hot filtration tests and found that catalytically active species is the heterogeneous nanoparticles. These results indicate that the use of phosphoramidite ligands as a stabilizer for developing efficient and unique chiral nanoparticles could open up a field for many other asymmetric organic transformations promoted by chiral catalysts.

One-step synthesis of PdCu@Ti3C2 with high catalytic activity in the Suzuki-Miyaura coupling reaction

Owing to their enhanced catalytic stability and cyclability, two-dimensional (2D) material-supported Pd-based bimetallic alloys have promising applications for catalytic reactions. Furthermore, the alloying strategy can effectively reduce costs and improve catalytic performance. In this paper, we report a one-step reduction method to synthesize a novel heterogeneous catalyst, PdCu@Ti3C2, with good catalytic performance. The composition and structure of the as-prepared catalyst were characterized by inductively coupled plasma-mass spectrometry (ICP-MS), scanning transmission electron microscopy (STEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). The catalyst particles, which were identified as a PdCu bimetallic alloy, exhibited good dispersion on the substrate. The performance of the catalyst in the Suzuki-Miyaura coupling reaction was studied, and the results showed that PdCu@Ti3C2 had excellent catalytic activity, similar to that of homogeneous Pd catalysts such as Pd(PPh3)4. Moreover, the prepared catalyst could be reused at least 10 times in the Suzuki-Miyaura coupling reaction with high yield.

Rapid one-pot synthesis of magnetically separable Fe3O4-Pd nanocatalysts: a highly reusable catalyst for the Suzuki-Miyaura coupling reaction

Heterogeneous catalysts comprising noble metals and magnetic materials allow a straightforward separation from a reaction using an external magnet and are recovered easily. In this study, we synthesized magnetic Fe₃O₄-Pd_n hybrid heterogeneous catalysts via a rapid one-pot aqueous-phase method. The synthesized Fe₃O₄-Pd NPs dispersed well with small size (∼50 nm), maintaining high magnetic responsiveness, and showed high reactivity and reusability for the Suzuki-Miyaura coupling reaction between aryl halides and phenylboronic acid. The synthesized Fe₃O₄-Pd₅₀ catalyst could be recycled at least ten times with no significant loss of catalytic activity by external magnet separation.

Pd-Pd/PdO as active sites on intercalated graphene oxide modified by diaminobenzene: fabrication, catalysis properties, synergistic effects, and catalytic mechanism

Pd-Pd/PdO nanoclusters well dispersed on intercalated graphene oxide (GO) (denoted as GO@PPD-Pd) were prepared and characterized. GO@PPD-Pd exhibited high catalytic activity (a TOF value of 60 705 h-1) during the Suzuki coupling reaction, and it could be reused at least 6 times. The real active centre was Pd(200)-Pd(200)/PdO(110, 102). A change in the Pd facets on the surface of PdO was a key factor leading to deactivation, and the aggregation and loss of active centres was also another important reason. The catalytic mechanism involved heterogeneous catalysis, showing that the catalytic processes occurred at the interface, including substrate adsorption, intermediate formation, and product desorption. The real active centres showed enhanced negative charge due to the transfer of electrons from the carrier and ligands, which could effectively promote the oxidative addition reaction, and Pd(200) and the heteroconjugated Pd/PdO interface generated in situ also participated in the coupling process, synergistically boosting activity. Developed GO@PPD-Pd was a viable heterogeneous catalyst that may have practical applications owing to its easy synthesis and stability, and this synergistic approach can be utilized to develop other transition-metal catalysts.

Modulation of the photocatalytic activity and crystallinity of F-TiO2 nanoparticles by using green natural carboxylic acids

Ultrareactive F-doped mesoporous TiO2 nanoparticles with potential environmental applications have been synthesized using green natural carboxylic acids.

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.

Pd-Catalyzed Oxidative Aminocarbonylation of Arylboronic Acids with Unreactive Tertiary Amines via C-N Bond Activation

An efficient synthesis of tertiary amides from aryl boronic acids and inert tertiary amines through the oxidative carbonylation via C(sp³)-N bond activation is presented. This protocol significantly restricts the homocoupling biarylketone product. It involves the use of a homogeneous PdCl₂/CuI catalyst and a heterogeneous Pd/C based catalyst, which promotes C(sp³)-N bond activation of tertiary amines with aryl boronic acids. This process represents a ligand-free, base-free, and recyclable catalyst along with an ideal oxidant like molecular oxygen.

Supported Palladium Catalyzed Carbonylative Coupling Reactions using Carbon Monoxide as C1 Source

The carbonylative reactions of aryl halides, boronic acids, amines, activated alkene and alkynes under CO and supported palladium catalyzed conditions are very popular reactions for the synthesis of bioactive molecules, pharmaceuticals, polymers, peptides, intermediates and fine chemicals synthesis. Due to cost effectiveness and easy handling of recyclable supported palladium catalyst, it became more popular among researchers either working in academic institute or industry. In recent years, irrespective of poisoning effect of CO with palladium as major limitation, several advancements have been done through surface selection, designing and condition improvement to achieve high yield in the area of carbonylative coupling reactions. We hope this review will be helpful as a ready reference of last 20 years in the field of CO insertion reactions using diverse range of supported palladium catalysts under carbon monoxide or its sources as C1 source.

Palladium oxide-decorated mesoporous silica on graphene oxide nanosheets as a heterogeneous catalyst for the synthesis of β-substituted indole derivatives

In this work, an efficient and facile strategy has been adopted for the stepwise synthesis of the RGO-MSiO2/PdO hybrid nanomaterial (HY-NM). Herein, a hybrid nanostructure of mesoporous silica over graphene oxide (GO) sheets has been developed followed by immobilizing palladium oxide nanoparticles (PdO NPs), and then it has been utilized for catalyzing a multicomponent reaction (MCR). To authenticate the successful synthesis of the HY-NM and successive immobilization of PdO NPs, various physicochemical characterization techniques were utilized such as SEM, EDAX, HR-TEM, HR-XRD, TGA, BET, FT-IR, and XPS analysis. The activity of the HY-NM has been determined by performing the catalyst-mediated synthesis of β-substituted indole derivatives (yield 90-98%). The excellent catalytic activity of the prepared HY-NM could be observed due to its high surface area and large porosity, which facilitates the penetration and interaction of reactant molecules with the catalytic active species. This protocol eliminates the requirement of further purification after the isolation of the product from the reaction mixture. The ease of handling, recyclability of the catalyst, and simple work-up procedure are the main features of this protocol. The synthesized HY-NM could be recycled for multiple catalytic cycles making it a very effective heterogeneous catalyst.

Catalytically active nanosized Pd9Te4 (telluropalladinite) and PdTe (kotulskite) alloys: first precursor-architecture controlled synthesis using palladium complexes of organotellurium compounds as single source precursors

Several intermetallic binary phases of Pd-Te including Pd3Te2, PdTe, PdTe2, Pd9Te4, Pd3Te, Pd2Te, Pd20Te7, Pd8Te3, Pd7Te2, Pd7Te3, Pd4Te and Pd17Te4 are known, and negligible work (except few studies on PdTe) has been done on exploring applications of such phases and their fabrication at nanoscale. Hence, Pd(ii) complexes Pd(L1)Cl2 and Pd(L2-H)Cl (L1): Ph-Te-CH2-CH2-NH2 and L2: HO-2-C6H4-CH[double bond, length as m-dash]N-CH2CH2-Te-Ph were synthesized. Under similar thermolytic conditions, complex Pd(L1)Cl2 with bidentate coordination mode of ligand provided nanostructures of Pd9Te4 (telluropalladinite) whereas Pd(L2-H)Cl with tridentate coordination mode of ligand yielded PdTe (kotulskite). Bimetallic alloy nanostructures possess high catalytic potential for Suzuki coupling of aryl chlorides, and reduction of 4-nitrophenol. They are also recyclable upto six reaction cycles in Suzuki coupling.

Recent progress in application of nanocatalysts for carbonylative Suzuki cross-coupling reactions

In the past few decades, cross-coupling of aryl halides and arylboronic acids in the presence of carbon monoxide (CO), also called carbonylative Suzuki coupling, to form two new carbon-carbon bonds in the production of synthetically and biologically important biaryl ketones, has been widely studied. Consequently, various catalytic systems have been extensively investigated in order to maximize the efficiency of this appealing area of biaryl ketone synthesis. As evidenced in the literature, nanometal-based systems are among the most powerful catalysts for this transformation as their large surface area to volume ratio and reactive morphologies allow faster reaction rates under milder CO pressure even at very low catalyst loadings. This review aims to provide an overview of the recent advances and achievements in the application of nano-sized metal catalysts for carbonylative Suzuki cross-coupling reactions, which may serve as an inspiration to researchers in their future work.

Suzuki–Miyaura cross coupling reaction: recent advancements in catalysis and organic synthesis

Suzuki–Miyaura cross coupling reaction (SMCR) – A milestone in the synthesis of C–C coupled compounds.

Ligand Steric Effects of α-Diimine Nickel(II) and Palladium(II) Complexes in the Suzuki-Miyaura Cross-Coupling Reaction

Nickel catalysts represent a low cost and environmentally friendly alternative to palladium-based catalytic systems for Suzuki-Miyaura cross-coupling (SMC) reactions. However, nickel catalysts have suffered from poor air, moisture, and thermal stabilities, especially at high catalyst loading, requiring controlled reaction conditions. In this report, we examine a family of mono- and dinuclear Ni(II) and Pd(II) complexes with a diverse and versatile α-diimine ligand environment for SMC reactions. To evaluate the ligand steric effects, including the bite angle in the reaction outcomes, the structural variation of the complexes was achieved by incorporating iminopyridine- and acenaphthene-based ligands. Moreover, the impact of substrate bulkiness was investigated by reacting various aryl bromides with phenylboronic acid, 2-naphthylboronic acid, and 9-phenanthracenylboronic acid. Yields were the best with the dinuclear complex, being nearly quantitative (93-99%), followed by the mononuclear complexes, giving yields of 78-98%. Consequently, α-diimine-based ligands have the potential to deliver Ni-based systems as sustainable catalysts in SMC.

Nickel(II) Nanoparticles Immobilized on EDTA-Modified Fe3O4@SiO2 Nanospheres as Efficient and Recyclable Catalysts for Ligand-Free Suzuki-Miyaura Coupling of Aryl Carbamates and Sulfamates

A highly efficient and air-, thermal-, and moisture-stable nickel-based catalyst with excellent magnetic properties supported on silica-coated magnetic Fe₃O₄ nanoparticles was successfully synthesized. It was well characterized by Fourier transform infrared spectroscopy, powder X-ray diffraction, transmission electron microscopy, field emission scanning electron microscopy, thermogravimetric analysis, dynamic light scattering (DLS), X-ray photoelectron spectroscopy, vibration sample magnetometry, energy-dispersive X-ray analysis, inductively coupled plasma analysis, and nitrogen adsorption-desorption isotherm analysis. The Suzuki-Miyaura coupling reaction between aryl carbamates and/or sulfamates with arylboronic acids was selected to demonstrate the catalytic activity and efficiency of the as-prepared magnetic nanocatalyst. Using the mentioned heterogeneous nanocatalyst in such reactions generated corresponding products in good to excellent yields in which the catalyst could easily be recovered from the reaction mixture with an external magnetic field to reuse directly for the next several cycles without significant loss of its activity.

An efficient and heterogeneous Pd-containing modified graphene oxide catalyst for preparation of biaryl compounds

In this research, a novel palladium-containing modified-graphene oxide (GO-N2S2/Pd) catalyst is designed and synthesized for the Suzuki-Miyaura reaction. The prepared catalyst was characterized by different techniques, such as thermogravimetric analysis (TGA), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), energy-dispersive X-ray (EDX), Raman spectroscopy, X-ray diffraction (XRD), and inductively coupled plasma optical emission spectrometry (ICP-OES). The catalytic performance of the synthesized catalyst was evaluated in the Suzuki cross-coupling reaction of phenylboronic acid and aryl halides with K2CO3 as a base. Good recoverability and reusability of this heterogeneous catalyst at the end of the reaction were observed.