Asymmetric aerobic oxidation of secondary alcohols catalyzed by poly(<i>N</i>-vinyl-2-pyrrolidone)-stabilized gold clusters modified with cyclodextrin derivatives

Hirano, Kiyotaka; Takano, Shinjiro; Tsukuda, Tatsuya

doi:10.1039/c9cc06770a

Cited by 12 publications

(10 citation statements)

References 46 publications

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“…In the reaction of aerobic asymmetric oxidation of alcohols, Tsukuda et al explored the effect of cyclodextrin derivative (abbreviated X-CD, with X = OH, NH 2 , or SH) modification of PVP-stabilized Au clusters (where PVP = poly( N -vinyl-2-pyrrolidone) with size <2 nm (atomically imprecise though). The enantioselectivity of product was evaluated by the selectivity factor ( s ), defined as k fast / k slow , where k fast and k slow are the rate constants for more and less reactive enantiomers in oxidation, respectively .…”

Section: Organic Transformation Reactionsmentioning

confidence: 99%

Toward Active-Site Tailoring in Heterogeneous Catalysis by Atomically Precise Metal Nanoclusters with Crystallographic Structures

et al. 2020

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Heterogeneous catalysis involves solid-state catalysts, among which metal nanoparticles occupy an important position. Unfortunately, no two nanoparticles from conventional synthesis are the same at the atomic level, though such regular nanoparticles can be highly uniform at the nanometer level (e.g., size distribution ∼5%). In the long pursuit of well-defined nanocatalysts, a recent success is the synthesis of atomically precise metal nanoclusters protected by ligands in the size range from tens to hundreds of metal atoms (equivalently 1−3 nm in core diameter). More importantly, such nanoclusters have been crystallographically characterized, just like the protein structures in enzyme catalysis. Such atomically precise metal nanoclusters merge the features of well-defined homogeneous catalysts (e.g., ligand-protected metal centers) and enzymes (e.g., protein-encapsulated metal clusters of a few atoms bridged by ligands). The well-defined nanoclusters with their total structures available constitute a new class of model catalysts and hold great promise in fundamental catalysis research, including the atomically precise size dependent activity, control of catalytic selectivity by metal structure and surface ligands, structure−property relationships at the atomic-level, insights into molecular activation and catalytic mechanisms, and the identification of active sites on nanocatalysts. This Review summarizes the progress in the utilization of atomically precise metal nanoclusters for catalysis. These nanocluster-based model catalysts have enabled heterogeneous catalysis research at the single-atom and single-electron levels. Future efforts are expected to achieve more exciting progress in fundamental understanding of the catalytic mechanisms, the tailoring of active sites at the atomic level, and the design of new catalysts with high selectivity and activity under mild conditions.

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Section: Organic Transformation Reactionsmentioning

confidence: 99%

Toward Active-Site Tailoring in Heterogeneous Catalysis by Atomically Precise Metal Nanoclusters with Crystallographic Structures

et al. 2020

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“…Accordingly, the strategy of postmodifications on the surface of metal clusters including ligand exchange, noncovalent encapsulation, and covalent conjugation provides a feasible approach to fully maintain the bioactivity of ligands and improve the biocompatibility of metal clusters with reduced side effects. The ligand exchange is the most common approach for the postmodification of metal nanoparticles, especially for the nucleotide-decorated Au nanoparticles or so-called spherical nucleic acids. − In this approach, thiol-free ligands such as synthetic polymers are used to stabilize metal clusters for further postmodification. − For instance, Hirano et al prepared 1.8 nm sized Au clusters by reducing HAuCl 4 using NaBH 4 in the presence of poly( N -vinyl-2-pyrrolidone) (PVP) in aqueous solutions, which were able to be further modified with thiol-containing cyclodextrins . In contrast to the ligand exchange, the noncovalent encapsulation and covalent conjugation can be used for thiol-protected metal clusters. − For instance, Higbee-Dempsey et al reported an Au cluster containing micelle by encapsulating acetal-modified dextran-protected Au clusters with the poly(ethylene glycol)- block -poly(ε-caprolactone) (PEG-PCL) through the hydrophobic interaction as the driving force .…”

Section: Surface Engineeringmentioning

confidence: 99%

“…164−166 For instance, Hirano et al prepared 1.8 nm sized Au clusters by reducing HAuCl 4 using NaBH 4 in the presence of poly(N-vinyl-2pyrrolidone) (PVP) in aqueous solutions, which were able to be further modified with thiol-containing cyclodextrins. 167 In contrast to the ligand exchange, the noncovalent encapsulation and covalent conjugation can be used for thiol-protected metal clusters. 168−171 For instance, Higbee-Dempsey et al reported an Au cluster containing micelle by encapsulating acetalmodified dextran-protected Au clusters with the poly(ethylene glycol)-block-poly(ε-caprolactone) (PEG-PCL) through the hydrophobic interaction as the driving force.…”

Section: Surface Engineeringmentioning

confidence: 99%

Catalytic Nanomaterials toward Atomic Levels for Biomedical Applications: From Metal Clusters to Single-Atom Catalysts

et al. 2021

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Single-atom catalysts (SACs) featuring the complete atomic utilization of metal, high-efficient catalytic activity, superior selectivity, and excellent stability have been emerged as a frontier in the catalytic field. Recently, increasing interests have been drawn to apply SACs in biomedical fields for enzyme-mimic catalysis and disease therapy. To fulfill the demand of precision and personalized medicine, precisely engineering the structure and active site toward atomic levels is a trend for nanomedicines, promoting the evolution of metal-based biomedical nanomaterials, particularly biocatalytic nanomaterials, from nanoparticles to clusters and now to SACs. This review outlines the syntheses, characterizations, and catalytic mechanisms of metal clusters and SACs, with a focus on their biomedical applications including biosensing, antibacterial therapy, and cancer therapy, as well as an emphasis on their in vivo biological safeties. Challenges and future perspectives are ultimately prospected for SACs in diverse biomedical applications.

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“…A gold-PVP powder with Au 0 clusters (1.8 � 0.6 nm) was made by mixing poly-N-vinyl-2-pyrrolidone (PVP,~40 kDa) with HAuCl 4 followed by reduction with NaBH 4 , dialysis, ultrafiltration, and liophylization. [72] It was used in the presence of functionalized CDs in the aerobic oxidative kinetic resolution of racemic secondary alcohols (�)-26 to form alcohols 27 (Scheme 8). Resolution efficiency was characterized by the s factor defined as k fast /k slow (rate constants of the more and less reactive enantiomers in oxidation).…”

Section: Oxidation Of Alcoholsmentioning

confidence: 99%

Synthetic Application of Cyclodextrins in Combination with Metal Ions, Complexes, and Metal Particles

Molnár

2020

ChemCatChem

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Cyclodextrins are green, environmentally benign products available through the enzymatic degradation of starch for a multitude of varied applications. This review attempts to collect useful information with respect to catalytic studies performed with the use of cyclodextrin and modified cyclodextrin preparations applied in combination of or loaded with varied catalytically active species including metal ions, complexes, and metal particles. Major sections are about their use in hydrogenation, reduction, oxidation, hydroformylation and coupling reactions. Additional sections include their utilization in ring formation and ring opening as well as degradation of pollutants. In the last part, examples about ester hydrolysis, hydroboration and hydrosilylation, as well as hydrogen production are treated. Data collected and analyzed indicate the importance and high potential of cyclodextrin-based catalysts in sustainable chemistry.

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Asymmetric aerobic oxidation of secondary alcohols catalyzed by poly(N-vinyl-2-pyrrolidone)-stabilized gold clusters modified with cyclodextrin derivatives

Abstract: Surface modification of poly(N-vinyl-2-pyrrolidone)-stabilized gold clusters (1.8 ± 0.6 nm) with aminated cyclodextrins induced aerobic oxidative kinetic resolution of racemic secondary alcohols (krel = 1.2).

Cited by 12 publications

References 46 publications

Toward Active-Site Tailoring in Heterogeneous Catalysis by Atomically Precise Metal Nanoclusters with Crystallographic Structures

Toward Active-Site Tailoring in Heterogeneous Catalysis by Atomically Precise Metal Nanoclusters with Crystallographic Structures

Catalytic Nanomaterials toward Atomic Levels for Biomedical Applications: From Metal Clusters to Single-Atom Catalysts

Synthetic Application of Cyclodextrins in Combination with Metal Ions, Complexes, and Metal Particles

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