Stabilized Palladium Nanoparticles Research Articles

Synthesis of 3‐Acyl‐1‐Indenones by Oxidative Cyclization of Symmetrical and Unsymmetrical Aryldiynes Using Palladium Nanoparticles (Pd‐BNP) as Reusable Nano Catalyst

AbstractAn efficient, stable and reusable binaphthyl stabilized palladium nanoparticles (Pd‐BNP) catalyzed synthesis of 3‐acyl‐1‐indenone derivatives from oxidative cyclization of symmetrical and unsymmetrical aryldiynes using DMSO as a solvent as well as an oxidant has been established. The scope of the reaction has been studied with various aryldiynes having electron‐donating and electron‐withdrawing groups that afforded good yields. Pd‐BNP catalyst can be recovered and reused for up to four cycles without major changes in particle size and reactivity.

Apple polysaccharide stabilized palladium nanoparticles for sensitive detection of organophosphorus pesticide

The widespread application of organophosphorus pesticides (OPs) has inflicted significant damage on human well-being and food security. Hence, it is imperative to develop a friendly and accessible biosensor for the detection of OPs. Herein, apple polysaccharide (AP) stabilized palladium nanoparticles (AP-PdnNPs) with a particle size of 2.75–5.95 nm were prepared using AP as a stabilizer and reducing agent. AP-Pd30NPs exhibited good peroxidase-like activity and effectively decomposed H2O2 to ·OH, which catalyzed the 3,3′,5,5′-tetramethylbenzidine system to become blue. The catalytic kinetics of AP-Pd30NPs conformed to the typical Michelis-Menten equation. Furthermore, OPs directly inhibited the peroxidase-like activity of AP-Pd30NPs. Thus, a highly effective colorimetric biosensor was developed for the detection of OPs. The detection range of the biosensor was 0.050 μg/L - 200 mg/L, and the limit of detection was extremely low to 0.010 μg/L. Compared with other nanomaterials, the detection platform based on AP-Pd30NPs can effectively detect organophosphorus pesticides without coupling natural enzymes；this method is more economical and practical. Therefore, this established method explores good perspective for the detection of OPs.

Boosting catalytic activity of π-π interactions-stabilized PdNPs for water-mediated Suzuki couplings of aryl chlorides

Utilizing unique interactions to enhance the catalytic performance of supported metal catalysts is a crucial strategy in catalyst design, albeit one that presents a significant challenge. This study introduces an original approach involving the use of π-π interactions to stabilize palladium nanoparticles (PdNPs) with a 2Br-substituted imidazolium-based covalent organic framework (COF, IHP-Br-PdNPs) for efficient water-mediated Suzuki reactions involving deactivated aryl chlorides and arylboronic acids at ambient conditions. Through extensive structural characterization employing techniques including Fourier transform infrared spectroscopy (FT-IR), cross-polarization magic angle spinning carbon-13 nuclear magnetic resonance (CP/MAS 13C NMR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), N2 adsorption, and X-ray photoelectron spectroscopy (XPS), we demonstrate the immobilization of highly stable and well-dispersed PdNPs was obtained. The designed IHP-Br-PdNPs demonstrate stability for up to 36 months in ambient air and can be efficiently recycled. After 9 catalytic cycles, there was no significant decline in catalytic performance, and the particle size of PdNPs remained constant at approximately 4-8 nm throughout the reactions. The coordination mode between the stabilizer and metal, specifically the π-π interaction between the 2Br-substituted imidazolium moiety and the Pd metal surface, plays a key role in stabilizing various active species and facilitating distinct catalytic pathways. This study provides valuable insights into the development of π-π interactions supported metal catalysts, which enhance stability and catalytic activity in advanced water-mediated synthesis applications.

Highly ordered Periodic Mesoporous Organosilica material containing the ionic 4,4-bipyridinium group and decorated with palladium nanoparticles: A proposal for nanoreactor

A Periodic Mesoporous Organosilica (PMO) containing the cationic 4,4-bipyridinium group, presenting 0.25 mmol g−1 that corresponds to 11.5 w/w%, was successfully prepared. This material was designed to have the ionic group acting as anchoring agent of PdCl42- anion complex, in a much lower amount than the available cationic sites (3 and 15 molar%). Subsequently, the palladium complex was in situ reduced to obtain stabilized palladium nanoparticles (PdNP). The ensemble of characterization results showed that the PMO material walls have a cylindrical morphology with hexagonal packing, generating well-ordered pores with a narrow size distribution and high surface area, even after being decorated with PdNP. This material is a candidate to be an efficient nanoreactor considering that it contains spatial uniformity in its chemical sites and confined environment. Aiming to evaluate the availability of palladium sites, the material was used as a catalyst in the reduction of p-nitrophenol model reaction. Although the catalyst of the present study has a comparable activity with other already reported systems, it presents the impressive lowest molar palladium/p-nitrophenol ratio found in literature.

Carbonized cellulose microspheres loaded with Pd NPs as catalyst in p-nitrophenol reduction and Suzuki-Miyaura coupling reaction

Catalytic reduction of p-nitrophenol is usually carried out using transition metal nanoparticles such as gold, palladium, silver, and copper, especially palladium nanoparticles (Pd NPs), which are characterized by fast reaction rate, high turnover frequency, good selectivity, and high yield. However, the aggregation and precipitation of the metals lead to the decomposition of the catalyst, which results in a significant reduction of the catalytic activity. Therefore, the preparation of homogeneous stabilized palladium nanoparticles catalysts has been widely studied. Stabilized palladium nanoparticles mainly use synthetic polymers. Cellulose microspheres, as a natural polymer material with low-cost and porous fiber network structure, are excellent carriers for stabilizing metal nanoparticles. Cellulose microspheres impregnated with palladium metal nanoparticles were carbonized to have a larger specific surface area and highly dispersed palladium nanoparticles, which exhibited excellent catalytic activity in the catalytic reduction of p-nitrophenol. In this work, the cellulose carbon-based microspheres palladium (Pd@CCM) catalysts were designed and characterized by SEM, TEM, EDS, XRD, FTIR, XPS, TGA, BET, and so on. Furthermore, the catalytic performance of Pd@CCM catalysts was investigated via p-nitrophenol reduction, which showed high catalytic activity. This catalyst also exhibited excellent catalytic performance in the Suzuki-Miyaura coupling reaction. Linking aromatic monomer and benzene through Suzuki-Miyaura coupling was presented as an effective route to obtaining biaryls, and the synthesis method is low-cost and simple. In addition, Pd@CCM showed desirable recyclability while maintaining its catalytic activity even after five recycles. This work is highly suggestive of the design and application of the heterogeneous catalyst.

Efficient heck and Suzuki-Miyaura cross-coupling reactions catalyzed by heterogeneous Pd NPs-decorated porous MOF catalysts under mild conditions

Carbon-carbon coupling reactions are extremely interesting for a variety of applications, including pharmaceuticals and biologically active compounds. In this study, we investigated the utilization of functionalized MIL-101 porous MOF for stabilizing palladium nanoparticles (NPs) and examined their catalytic performance in the cross-coupling reaction of aryl halides with phenylboronic acid and methyl acrylate under mild conditions. To achieve this, MIL-101(Al) was synthesized using a solvothermal method, followed by functionalization with environmentally friendly l-Cysteine (CYS). Subsequently, the MIL-101(Al)-CYS compound was immersed in an ethanolic solution of palladium and stirred overnight. The catalyst exhibited remarkable efficiency (over 90 %) in Suzuki and Heck cross-coupling reactions, demonstrating excellent activity and recyclability. The reactions were conducted in polyethylene glycol 200 (PEG 200), a green reaction medium, at temperatures of 70 °C and 60 °C, with Pd loadings of 0.22 and 0.08 mol%, respectively. MOF-based catalysts, owing to their highly tunable structures and porosity, hold great promise as heterogeneous catalysts in organic reactions.

Stabilized Palladium Nanoparticles from Bis-(N-benzoylthiourea) Derived-PdII Complexes as Efficient Catalysts for Sustainable Cross-Coupling Reactions in Water.

Stable palladium (II) complexes, incorporating a double (N-benzoylthiourea) arrangement bonded to a complex heterocyclic scaffold, are used as precursors of catalytic species able to promote Suzuki-Miyaura, Mizoroki-Heck, Hiyama, Buchwald-Hartwig, Hirao and Sonogashira-Hagihara cross-coupling transformations in water. These sustainable processes are chemoselective and very versatile. The nanoparticles responsible for these catalytic reactions were analyzed and studied. Their usefulness is demonstrated after several tests and analyses. The heterogeneous character of this species in water was also confirmed.

Ecofriendly synthesis of Salmalia Malabarica gum stabilized palladium nanoparticles: antibacterial and catalytic properties

AbstractEffluents containing dyes, discharged by various industries, have become a significant contributor to water pollution. This study explores the use of green-synthesized palladium nanoparticle (PdNP) catalysts, which offer enhanced catalytic performance compared to traditional methods. The research focuses on the synthesis of palladium nanoparticles using Salmalia Malabarica (SM) gum via a microwave-assisted process and investigates their catalytic and antibacterial properties. SEM analysis confirms the even distribution of PdNPs on the surface of SM gum. Furthermore, TEM analysis reveals a PdNPs size distribution of 10 ± 2 nm. XPS study was used to identify the chemical state of Pd in the synthesized nanoparticles. The results demonstrate that PdNPs are highly effective catalysts for the degradation of dyes such as Methylene Orange (MO), Rhodamine-B (Rh-B), and 4-Nitrophenol (4-NP), even after being reused five times. The catalytic activity of PdNPs was remarkable, achieved 99% dye degradation in four minutes. The degradation data of PdNPs on 4 -NP, MO and Rh-B dyes are followed by pseudo-first-order kinetics with 0.0087, 0.0152 and 0.0164 s− 1, respectively. Additionally, PdNPs exhibit exceptional antimicrobial activity against both bacterial and fungal strains. This synthesis process proves to be cost-effective, devoid of toxic chemicals, and remarkably rapid. The findings suggest promising applications for PdNPs in fields like nanomedicine and environmental remediation, reflecting their potential for addressing water pollution issues.

Magnetically retractable tea extract stabilized palladium nanoparticles for denitrogenative cross-coupling of aryl bromides with arylhydrazines under green conditions: An alternate route for the biaryls synthesis

Novel palladium based magnetic nanocatalyst was synthesized by the co-precipitation method and coated with silica and tea extract as stabilizing agent. Palladation onto the prepared nanocomposite was done to get ION-SiO2/TE-Pd(0) catalyst. Our study is one of the limited number of studies reported for the catalytic denitrogenative coupling of arylbromide and arylhydrazine. This led to the construction of important substituted biaryls bearing various substituents with 82–92% yields. The synthesized nanocatalyst was characterized using structural and morphological characterization techniques. It was also observed that only 2 mol% of ION-SiO2/TE-Pd(0) catalyst was sufficient for the catalysis and reusable upto six cycles.

Microwave-assisted synthesis of Limonia acidissima Groff gum stabilized palladium nanoparticles for colorimetric glucose sensing

Herein, we present a novel microwave-assisted method for the synthesis of palladium nanoparticles (PdNPs) supported by Limonia acidissima Groff tree extract gum. The synthesized PdNPs were characterized using various analytical techniques, including FTIR, SEM, TEM, UV–visible, and powder XRD analyses. TEM and XRD analysis confirmed that the synthesized LAG-PdNPs are highly crystalline nature spherical shapes with an average size diameter of 7–9 nm. We employed these gum-capped PdNPs to investigate their peroxidase-like activity for colorimetric detection of hydrogen peroxide (H2O2) and glucose. The oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) by H2O2, catalyzed by PdNPs, produces oxidation products quantified at 652 nm using spectrophotometry. The catalytic activity of PdNPs was optimized with respect to temperature and pH. The developed method exhibited a linear range of detection from 1 to 50 µm, with detection limits of 0.35 µm for H2O2 and 0.60 µm for glucose.

Palladium-based pseudohomogeneous catalyst for highly selective aerobic oxidation of benzylic alcohols to aldehydes

This study presents a novel class of pseudohomogeneous catalysts (PHC) based on carbon quantum dots functionalized with terpyridine ligands (CQDs-Tpy) to immobilize and stabilize palladium nanoparticles (Pd NPs). Extensive characterization techniques clearly confirmed the successful stabilization of Pd NPs on CQDs-Tpy. The effectiveness of the catalyst was demonstrated in the selective aerobic oxidation of primary and secondary of benzylic alcohols to aldehydes in the absence of additives and phase transfer catalyst (PTC). Remarkably, the reactions predominantly yielded aldehydes without further oxidation to carboxylic acids. By employing low catalyst loadings (0.13 mol%), high conversions (up to 89%) and excellent selectivity (> 99%) of the aldehyde derivatives were achieved. Moreover, the CQDs-Tpy/Pd NPs catalyst displayed suitable catalytic activity and recyclability, offering potential economic advantages. This promising approach opens up new opportunities in the field of catalysis for designing subnanometric metal-based PHCs.

Schiff base stabilized palladium nanoparticles: Synthesis, characterization, catalytic degradation of organophosphorus pesticides, and fluorometric detection of Cr6+ in aqueous media

As a stabilizing and reducing agent, the Schiff base (2-(4-(trifluoromethoxy)phenylimino)methyl)-6-methoxyphenol) was used to synthesize palladium nanoparticles (PdNPs) with an average particle size (12 ± 2 nm) and a spherical shape. The numerous methods, including UV–vis absorption spectroscopy, photoluminescence (PL), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and thermal gravimetric analysis (TGA) were used to characterize the PdNPs. The Schiff base capped PdNPs have FCC structure with 10 ± 3 nm particle size was estimated from XRD and TEM analysis. The catalytic, sensing, antibacterial, and antioxidant abilities of the created PdNPs were assessed. The findings demonstrated that PdNPs followed pseudo-first-order kinetics and had superior catalytic activity in the degradation of pesticides (monocrotophos (MCP), 99.9%) and chlorpyrifos (CLP), 98.2%) using NaBH4 as a reducing agent in 1 h reaction. PdNPs were still stable and exhibited a high catalytic activity with only a marginal decrease from maximum degradation (99.9% of MCP and 98.2% of CLP) using the fresh catalyst to 92.6% (MCP) and 90.1% (CLP) of the used catalyst (recycled after 5 times) was observed. Additionally, at a concentration range of 10–100 µM, the PdNPs demonstrated selective fluorescence sensing for Cr6+ metal ions in aqueous media. The significant antimicrobial action was also shown by the PdNPs against pathogens such S. aureus, B. subtilis, E. coli, P. aeruginosa, A. niger, and C. albicans. The PdNPs also demonstrated antioxidant activity in the DPPH free radical scavenging assay, with a 78.06% scavenging efficiency. This technique is efficient and cost-effective, and it may be used as an effective biological agent, sensor, and catalyst for a variety of environmental applications.

Binaphthyl-Stabilized Palladium Nanoparticle-Catalyzed Stereoselective Synthesis of 3-Arylidene-2-oxindoles via One-Pot Heck-like Carbocyclization/Nucleophilic Addition.

Stereoselective, one-pot synthesis of 3-arylidene-2-oxindoles has been accomplished via Heck-like carbocyclization/nucleophilic addition of N-(2-iodophenyl)-N-methyl-3-phenylpropiolamide, phenylacetylene, and secondary amine using binaphthyl stabilized palladium nanoparticles (Pd-BNP) as a reusable catalyst. Less reactive aryl bromides generally provided a similar yield of 3-arylidene-2-oxindoles compared with more reactive aryl iodides. The Pd-BNP nanocatalyst has been recovered and recycled for five catalytic cycles with only an insignificant reduction in particle size, reactivity, and reaction yield.

Imidazole Functionalized Porous Organic Polymer Stabilizing Palladium Nanoparticles for the Enhanced Catalytic Dehydrogenative Coupling of Silanes with Alcohols

AbstractIn general, organic strong bases and precious metal complexes serve as catalysts in the dehydrogenative coupling reaction of silanes with alcohols. However, these catalysts can't be easily separated from the catalytic system. Moreover, the self‐polymerization of silanes usually occurs in the presence of strong bases. In this work, utilizing the coordination of imidazolium nitrogen with Pd metal nanoparticles, the alkaline imidazole‐functionalized porous organic polymer stabilized palladium nanoparticles (Pd/PDVB‐Vim) is developed to compensate for the above‐mentioned drawbacks. The Pd/PDVB‐Vim catalyst is characterized and applied in the dehydrogenative coupling reaction of silanes with alcohols under mild conditions (30 °C). The characterization results demonstrate the Pd NPs are uniformly dispersed on PDVB‐Vim with ultrasmall particle size (Ca. 2.00 nm) and the strong interaction of the nitrogen on PDVB‐Vim and Pd NPs is obvious in Pd/PDVB‐Vim. This strong interaction makes the Pd/PDVB‐Vim catalyst exhibits the best stability and reusability.

Asymmetric Suzuki Cross‐Coupling Reactions Catalyzed by Chiral Surfactant‐Stabilized Palladium Nanoparticles

AbstractWe report the synthesis of cinchonine and hydrocinchonine derived surfactants by reacting with various mono alkylating agents (hexyl, octyl, octadecyl, dodecyl bromides) and di‐alkylating agent such as α,α’‐p‐xylene‐di‐bromide. A series of chiral surfactants have been used to stabilize palladium nanoparticles (NPs) which are water soluble. These Pd NPs were utilized in asymmetric Suzuki cross coupling reaction of naphthalene boronic acids with substituted naphthalene bromides to get binaphthalenes and terephenylenes. It was observed that, the surfactant's alkyl‐chain length and the palladium source played a major role in this catalytic reaction. The high solubility and positive zeta potential of gemini‐surfactant (GS) stabilized Pd NPs make them attractive as a potential candidate for the synthesis of binaphthalenes and terephenylenes with high yields.

Palladium nanoparticles embedded over chitosan/γMnO2 composite hybrid microspheres as heterogeneous nanocatalyst for effective reduction of nitroarenes and organic dyes in water

Effective remediation of toxic organic pollutants such as nitroarenes and dyes from water systems is an important global issue for purification of drinking water or wastewater. Therefore, the development of effective strategies to treat these pollutants has recently become a critical and fundamental issue, and one of the most useful methodologies is to utilize heterogeneous catalysts. In this regard, a novel nano-sized heterogeneous catalyst system was designed in the present study by stabilizing palladium nanoparticles on the composite hybrid microspheres based on chitosan and γMnO2 which was developed as the stabilizer (Pd/CS/γMnO2). The morphological/structural characterization of Pd/CS/γMnO2 nanocatalyst was carried out by SEM, XRD, TEM, BET, EDS, FT-IR, and TG analyses. Then, the catalytic role of Pd/CS/γMnO2 nanocatalyst was evaluated towards catalytic reduction of some environmental pollutants such as 2-nitroaniline (2-NA), 4-nitrophenol (4-NP), 4-nitroaniline (4-NA), 4-nitro-o-phenylenediamine (4-NPD), congo red (CR), methylene blue (MB), methyl orange (MO), methyl red (MR), and rhodamine B (RhB) in water by using NaBH4 at room temperature. The tests showed that Pd/CS/MnO2 effectively and rapidly catalyzed the reduction of these pollutants and could be reused up to 8 cycles. Additionally, it was found that the catalytic activity of Pd/CS/γMnO2 nanocatalyst was superior to those of many catalysts against the same reduction reactions. This paper concludes that Pd/CS/γMnO2 nanocatalyst appears to have a high potential to serve as an effective catalyst for remediation of wastewater thanks to its facile preparation, low cost, and good catalytic activity.

Zwitterionic daptomycin stabilized palladium nanoparticles with enhanced peroxidase-like properties for glucose detection

Mimic enzymes, especially noble metal nanomaterials, replace natural horseradish peroxidase due to the artificial regulation of catalytic activity by adjusting particle size and morphology. However, the existing mimic enzymes still have disadvantages such as large particle size, easy clustering and poor biocompatibility. Herein, well-dispersed daptomycin stabilized palladium nanoparticles (Dap-Pdn NPs) were synthesized by using daptomycin as a biological template. The average particle size of palladium nanoparticles of Dap-Pd0.25 NPs was 1.73 nm, the hydrodynamic size of Dap-Pd0.25 NPs detected by DLS method was 49.97 nm, Dap-Pd0.25 NPs were stable in fibrinogen solution. In addition, Dap-Pd0.25 NPs had excellent peroxidase-like activity, which effectively catalyzed the colorimetric oxidation reaction of 3,3′,5,5′-tetramethylbenzidine (TMB) by H2O2. Dap-Pd0.25 NPs were used to detect glucose concentration based on the colorimetric reaction of TMB, which had a wide detection range (0.02–1 mM) and low detection limit (5.6 μM) for glucose. Besides, fluorescence experiments proved that Dap-Pdn NPs catalyzed H2O2 to generate·OH. Taken together, a simple, green and inexpensive synthesis method of palladium nanoparticles with enhanced peroxidase-like activity was proved in this research. Dap-Pdn NPs will have great application prospects in biological detection in the future.

Synthesis and characterization of supported stabilized palladium nanoparticles for selective hydrogenation in water at low temperature.

Zirconia supported vacant phosphotungstate stabilized Pd nanoparticles (Pd–PW11/ZrO2) were prepared using a simple impregnation and post reduction method, characterized and their efficiency for selective C Created by potrace 1.16, written by Peter Selinger 2001-2019 ]]> C hydrogenation of unsaturated compounds explored. The establishment of a hydrogenation strategy at low temperature using water as solvent under mild conditions makes the present system environmentally benign and green. The catalyst shows outstanding activity (96% conversion) with just a small amount of Pd(0) (0.0034 mol%) with high substrate/catalyst ratio (29 177/1), TON (28 010) and TOF (14 005 h−1) for cyclohexene (as a model substrate) hydrogenation. The catalyst was recovered by simple centrifugation and reused for up to five catalytic cycles without alteration in its activity. The present catalyst was found to be viable towards different substrates with excellent activity and TON (18 000 to 28 800). A study on the effect of addenda atom shows that the efficiency of the catalyst can be enhanced greatly by increasing the number of counter protons. This challenging strategy would greatly benefit sustainable development in chemistry as it diminishes the use of organic solvents and offers economic and environmental benefits as water is cheap and non-toxic.

Palladium Nanoparticle-Catalyzed Stereoselective Domino Synthesis of All-Carbon Tetrasubstituted Olefin Containing Oxindoles via Carbopalladation/C-H Activation.

The binaphthyl stabilized palladium nanoparticles (Pd-BNP) catalyzed single-step, stereoselective domino synthesis of symmetrically and unsymmetrically all-carbon tetrasubstituted olefin containing oxindoles from readily accessible anilides has been developed. The Pd-BNP catalyst showed a wide range of functional group tolerance that enabled building a library of heteroaromatics. This reusable Pd catalyst reflected its utility in the synthesis of biologically important AMP-activated protein kinase deprived of any metal Pd contamination. The nanocatalyst was easily recovered and reused five times without any appreciable loss in particle size or catalytic activity.

Cyclodextrin ‐ Stabilized Palladium Nanoparticles on Ceria: Investigation of Support Interactions and Pivotal Promotion in the Suzuki‐Miyaura Reaction

AbstractThe present work is focused on the understanding of the CeO2 support interactions with cyclodextrin‐stabilized palladium nanoparticles (PdNPs) and the effect in the Suzuki‐Miyaura reaction outcome. Mostly, it is evidenced the strong influence of the cyclodextrin torus on the reactivity of PdNPs towards the ceria matrix. Structural characterization by X‐rays photoelectron spectroscopy (XPS) Raman spectroscopy, diffuse reflectance spectroscopy (DRS) and powder X‐rays diffraction (XRD, via Rietveld refinement) afforded to infer that palladium is being partially brought into the CeO2 structure. Transmission electron microscopies (TEM and STEM) visualizations allowed to evidence a bimodal size distribution of PdNPs (1–5 nm and 20–100 nm) over the catalysts even though particles up to 5 nm are probably the most responsible for the catalytic results reported herein.