scholarly journals Cyclodextrin polymer networks decorated with subnanometer metal nanoparticles for high-performance low-temperature catalysis

2019 ◽  
Vol 5 (11) ◽  
pp. eaax6976 ◽  
Author(s):  
Tiefan Huang ◽  
Guan Sheng ◽  
Priyanka Manchanda ◽  
Abdul H. Emwas ◽  
Zhiping Lai ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Metal Nanoparticles ◽  
Rational Design ◽  
Polymer Network ◽  
Polymer Networks ◽  
Coupling Reaction ◽  
High Catalytic Activity ◽  
Support Materials ◽  
Cyclodextrin Polymer ◽  
Coordination Sites

The synthesis of support materials with suitable coordination sites and confined structures for the controlled growth of ultrasmall metal nanoparticles is of great importance in heterogeneous catalysis. Here, by rational design of a cross-linked β-cyclodextrin polymer network (CPN), various metal nanoparticles (palladium, silver, platinum, gold, and rhodium) of subnanometer size (<1 nm) and narrow size distribution are formed via a mild and facile procedure. The presence of the metal coordination sites and the network structure are key to the successful synthesis and stabilization of the ultrasmall metal nanoparticles. The as-prepared CPN, loaded with palladium nanoparticles, is used as a heterogeneous catalyst and shows outstanding catalytic performance in the hydrogenation of nitro compounds and Suzuki-Miyaura coupling reaction under mild conditions. The CPN support works synergistically with the metal nanoparticles, achieving high catalytic activity and selectivity. In addition, the catalytic activity of the formed catalyst is controllable.

High Catalytic Activity of Pd Nanoparticles Synthesized from Green Alga Chlorella vulgaris in Buchwald-hartwig Synthesis of N-Aryl Piperazines

2019 ◽  
Vol 7 (1) ◽  
pp. 23-33
Author(s):  
Vaibhav Mishra ◽  
Anju Arya ◽  
Tejpal Singh Chundawat
Keyword(s):  
Catalytic Activity ◽  
Green Alga ◽  
Chlorella Vulgaris ◽  
Direct Synthesis ◽  
Coupling Reaction ◽  
Pd Nanoparticles ◽  
High Catalytic Activity ◽  
Pd Nanoparticle ◽  
Green Algal ◽  
Green Alga Chlorella

Background: The N-aryl piperazines are an important component of many drug products used for the treatment of malaria, depression, anxiety and Parkinson diseases. Buchwald-Hartwig amination is the latest and well-known reaction for Pd catalyzed direct synthesis of N-aryl piperazine from aryl halides. Although several Pd-ligand systems have already been discovered for this conversion, Pd nanoparticles are recently being used for this useful coupling reaction due to their recyclability and durability. Metal nanoparticles show enhanced catalytic activity compared to their bulk counterparts due to increased surface area at the edges and corners. The use of green algal extract in place of chemical ligands makes this process more environment-friendly and cost-effective. In this research, Pd nanoparticles synthesized using green alga C. Vulgaris were utilized as an alternative approach for the coupling reaction during the preparation of N-aryl piperazines. Methods: Synthesized Pd nanoparticles from C. Vulgaris were characterized by FTIR, SEM and XRD techniques. The catalytic activity of the synthesized nanoparticles was monitored for the synthesis of N-aryl piperazines by Buchwald-Hartwig reaction. The synthesized N-aryl piperazines were characterized by NMR, FTIR and mass analysis. Results: A very good catalytic activity of the synthesized Pd nanoparticles from green alga Chlorella vulgaris extract was observed. The green alga not only reduces the size of the Pd metal to nanoparticles but also acts as a green ligand for reduction of Pd(II) to Pd(0) during nanoparticle synthesis. Using this Pd nanoparticles-green ligand system, several N-aryl piperazines were synthesized in good to excellent yields. Reaction conditions for better conversion were optimized. The comparative advantage of the catalytic system with recently published works on Buchwald-Hartwig C-N coupling reaction is given. Recyclability and durability of the catalyst were explored and the results were found to be promising. A plausible mechanism of Pd nanoparticle catalyzed reaction is also proposed. Conclusion: Catalytic activity of the Pd nanoparticle synthesized from Chlorella vulagris in the synthesis of N-aryl piperazines by Buchwald-Hartwig reaction is reported first time to the best of our knowledge and understanding. The green approach of Pd catalyst to facilitate the reaction and its environmental impact is the main characteristic of the process.

scholarly journals Palladium/phosphorus-functionalized porous organic polymer with tunable surface wettability for water-mediated Suzuki–Miyaura coupling reaction

RSC Advances ◽  
2019 ◽  
Vol 9 (63) ◽  
pp. 36600-36607 ◽  
Author(s):  
Yizhu Lei ◽  
Zaifei Chen ◽  
Guangxing Li
Keyword(s):  
Catalytic Activity ◽  
Coupling Reaction ◽  
Surface Wettability ◽  
Organic Polymer ◽  
High Catalytic Activity ◽  
Aryl Chlorides ◽  
Porous Organic Polymer

A palladium/phosphorus-functionalized porous organic polymer with tunable surface wettability was successfully prepared. The catalyst displayed high catalytic activity for the water-mediated Suzuki–Miyaura coupling reaction of aryl chlorides.

scholarly journals Surfactant encapsulated palladium-polyoxometalates: controlled assembly and their application as single-atom catalysts

2016 ◽  
Vol 7 (2) ◽  
pp. 1011-1015 ◽  
Author(s):  
Peilei He ◽  
Biao Xu ◽  
Xiaobin Xu ◽  
Li Song ◽  
Xun Wang
Keyword(s):  
Catalytic Activity ◽  
Coupling Reaction ◽  
Single Atom ◽  
High Catalytic Activity ◽  
Controlled Assembly

Two kinds of assembly structures (nanorolls and hollow spindles) based on the palladium substituted Wells–Dawson polyoxometalate (Pd-POM) were synthesised and showed high catalytic activity for both the Suzuki–Miyaura coupling reaction and semihydrogenation reaction.

scholarly journals Disentangling the size-dependent geometric and electronic effects of palladium nanocatalysts beyond selectivity

2019 ◽  
Vol 5 (1) ◽  
pp. eaat6413 ◽  
Author(s):  
Hengwei Wang ◽  
Xiang-Kui Gu ◽  
Xusheng Zheng ◽  
Haibin Pan ◽  
Junfa Zhu ◽  
...  
Keyword(s):  
Metal Nanoparticles ◽  
Rational Design ◽  
Aerobic Oxidation ◽  
Atomic Layer ◽  
Electronic Effects ◽  
Coordination Sites ◽  
Layer Deposition ◽  
Palladium Nanocatalysts ◽  
The Right ◽  
Site Selective

The prominent size effect of metal nanoparticles shapes decisively nanocatalysis, but entanglement of the corresponding geometric and electronic effects prevents exploiting their distinct functionalities. In this work, we demonstrate that in palladium (Pd)–catalyzed aerobic oxidation of benzyl alcohol, the geometric and electronic effects interplay and compete so intensively that both activity and selectivity showed in volcano trends on the Pd particle size unprecedentedly. By developing a strategy of site-selective blocking via atomic layer deposition along with first principles calculations, we disentangle these two effects and unveil that the geometric effect dominates the right side of the volcano with larger-size Pd particles, whereas the electronic effect directs the left of the volcano with smaller-size Pd particles substantially. Selective blocking of the low-coordination sites prevents formation of the undesired by-product beyond the volcano relationship, achieving a remarkable benzaldehyde selectivity and activity at the same time for 4-nm Pd. Disentangling the geometric and electronic effects of metal nanoparticles opens a new dimension for rational design of catalysts.

scholarly journals N,N-Dimethylformamide-stabilized copper nanoparticles as a catalyst precursor for Sonogashira–Hagihara cross coupling

RSC Advances ◽  
2017 ◽  
Vol 7 (37) ◽  
pp. 22869-22874 ◽  
Author(s):  
Hideo Oka ◽  
Katsuya Kitai ◽  
Takeyuki Suzuki ◽  
Yasushi Obora
Keyword(s):  
Catalytic Activity ◽  
Copper Nanoparticles ◽  
Coupling Reaction ◽  
Cross Coupling ◽  
High Catalytic Activity ◽  
Catalyst Precursor ◽  
Cross Coupling Reaction

We found that DMF-stabilized Cu NPs have high catalytic activity in the Sonogashira cross-coupling reaction at low catalyst loadings (0.2 mol%).

Towards rational design of core–shell catalytic nanoreactor with high performance catalytic hydrogenation of levulinic acid

2016 ◽  
Vol 6 (13) ◽  
pp. 5102-5115 ◽  
Author(s):  
Biplab Banerjee ◽  
Ramana Singuru ◽  
Sudipta K. Kundu ◽  
Karnekanti Dhanalaxmi ◽  
Linyi Bai ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Catalytic Hydrogenation ◽  
Levulinic Acid ◽  
High Performance ◽  
Rational Design ◽  
Core Shell ◽  
High Catalytic Activity

Core–shell catalytic nanoreactor was designed, exhibiting high catalytic activity for levulinic acid hydrogenation.

scholarly journals Novel amphiphilic polyvinylpyrrolidone functionalized silicone particles as carrier for low-cost lipase immobilization

2018 ◽  
Vol 5 (6) ◽  
pp. 172368 ◽  
Author(s):  
Shan Zhang ◽  
Qianchun Deng ◽  
Ya Li ◽  
Mingming Zheng ◽  
Chuyun Wan ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Rational Design ◽  
Low Cost ◽  
Immobilized Lipase ◽  
High Catalytic Activity ◽  
Lipase Immobilization ◽  
X Ray ◽  
Support Materials ◽  
Steady Rate ◽  
Loading Amount

The high catalytic activity, specificity and stability of immobilized lipase have been attracting great interest. How to reduce the cost of support materials has always been a hot topic in this field. Herein, for the development of low-cost immobilized lipase, we demonstrate an amphiphilic polyvinylpyrrolidone (PVP) grafted on silicone particle (SP) surface materials (SP-PVP) with a rational design based on interfacial activation and solution polymerization. Meanwhile, hydrophilic pristine SP and hydrophobic polystyrene-corded silicone particles (SP-Pst) were also prepared for lipase immobilization. SP-PVP was characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and thermogravimetry. Our results indicated that the lipase loading amount on the SP-PVP composites was about 215 mg of protein per gram. In the activity assay, the immobilized lipase SP-PVP@CRL exhibited higher catalysis activity and better thermostability and reusability than SP@CRL and SP-Pst@CRL. The immobilized lipase retained more than 54% of its initial activity after 10 times of re-use and approximately trended to a steady rate in the following cycles. By introducing the interesting amphiphilic polymer to this cheap and easily obtained SP surface, the relative performance of the immobilized lipase can be significantly improved, facilitating interactions between the low-cost support materials and lipase.

scholarly journals Facile Synthesis and Characterization of Palladium@Carbon Catalyst for the Suzuki-Miyaura and Mizoroki-Heck Coupling Reactions

2021 ◽  
Vol 11 (11) ◽  
pp. 4822
Author(s):  
Hamed M. Alshammari ◽  
Obaid F. Aldosari ◽  
Mohammad Hayal Alotaibi ◽  
Raja L. Alotaibi ◽  
Mosaed S. Alhumaimess ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Activated Carbon ◽  
Coupling Reaction ◽  
Aryl Halides ◽  
High Catalytic Activity ◽  
Coupling Reactions ◽  
Heck Coupling ◽  
Efficient Catalyst ◽  
X Ray ◽  
Suzuki Reactions

Palladium-based carbon catalysts (Pd/C) can be potentially applied as an efficient catalyst for Suzuki–Miyaura and Mizoroki–Heck coupling reactions. Herein, a variety of catalysts of palladium on activated carbon were prepared by varying the content of ‘Pd’ via an in situ reduction method, using hydrogen as a reducing agent. The as-prepared catalysts (0.5 wt % Pd/C, 1 wt % Pd/C, 2 wt % Pd/C and 3 wt % Pd/C) were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and Brunauer–Emmett–Teller (BET) analyses. The catalysts were tested as a coupling catalyst for Suzuki–Miyaura coupling reactions involving aryl halides and phenyl boronic acid. The optimization of the catalyst by varying the palladium content on the activated carbon yielded Pd/C catalysts with very high catalytic activity for Suzuki reactions of aryl halides and a Mizoroki–Heck cross-coupling reaction of 4-bromoanisol and acrylic acid in an aqueous medium. A high ‘Pd’ content and uniform ‘Pd’ impregnation significantly affected the activity of the catalysts. The catalytic activity of 3% Pd/C was found to make it a more efficient catalyst when compared with the other synthesized Pd/C catalysts. Furthermore, the catalyst reusability was also tested for Suzuki reactions by repeatedly performing the same reaction using the recovered catalyst. The 3% Pd/C catalyst displayed better reusability even after several reactions.

scholarly journals A base-free Chan–Lam reaction catalyzed by an easily assembled Cu(II)-carboxylate metal-organic framework

2021 ◽  
pp. 174751982110265
Author(s):  
Xinhai Zhang ◽  
Jianhua Qin ◽  
Ruixuan Ma ◽  
Lei Shi
Keyword(s):  
Catalytic Activity ◽  
Heterogeneous Catalyst ◽  
Metal Organic Framework ◽  
Coupling Reaction ◽  
High Catalytic Activity ◽  
Arylboronic Acids ◽  
Metal Organic ◽  
Organic Framework

A new copper(II) metal-organic framework is constructed as a sustainable copper heterogeneous catalyst. Cu-DPTCA, with high catalytic activity, can effectively promote the Chan–Lam coupling reaction of arylboronic acids and amines without adding any base or additive.

2D ultrathin surfactant-encapsulating polyoxometalate assemblies as carriers for monodispersing noble-metal nanoparticles with high catalytic activity and stability

2021 ◽  
Author(s):  
Yang-Guang Li ◽  
Xing-Yu Ji ◽  
Feiyang Yu ◽  
Yingqi Li ◽  
Hao-Tian Zhu ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Metal Nanoparticles ◽  
Uniform Distribution ◽  
Noble Metal ◽  
Environmental Governance ◽  
Noble Metal Nanoparticles ◽  
High Catalytic Activity ◽  
Binding Force ◽  
Strong Binding

Noble-metal nanoparticles (NMNPs) with excellent catalytic activity and stability play an important role in the field of environmental governance. Uniform distribution and strong binding force with carriers of noble-metal nanoparticles...

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