Aminooxy (–ONH2) groups are well known for their chemoselective reactions with carbonyl compounds, specifically aldehydes and ketones. The versatility of aminooxy chemistry has proven to be an attractive feature that continues to stimulate new applications. This work describes application of aminooxy click chemistry on the surface of gold nanoparticles. A trifunctional amine‐containing aminooxy alkane thiol ligand for use in the functionalization of gold monolayer‐protected clusters (Au MPCs) is presented. Diethanolamine is readily transformed into an organic‐soluble aminooxy thiol (AOT) ligand using a short synthetic path. The synthesized AOT ligand is coated on ≤2‐nm‐diameter hexanethiolate‐(C6S)‐capped Au MPCs using a ligand‐exchange protocol to afford organic‐soluble AOT/C6S (1:1 ratio) Au mixed monolayer‐protected clusters (MMPCs). The synthesis of these Au(C6S)(AOT) MMPCs and representative oximation reactions with various types of aldehyde‐containing molecules is described, highlighting the ease and versatility of the chemistry and how amine protonation can be used to switch solubility characteristics.
Glutathione-protected Pd, PdAu and PdPt nanoparticles (NPs) show greatly increased reactivity and stability towards the hydrogenation/isomerization of allyl alcohol in a biphasic organic/aqueous solvent mixture compared to single-phase alkanethiol-protected Pd-based NPs. NPs synthesized under aerobic conditions have higher activity compared to those synthesized under nitrogen, with the highest TOF of 676 mole product/mole metal/hour for 75 : 25 PdAu NPs at 20 mL/min H 2 flow. 75 : 25 PdAu NPs prepared under nitrogen have a maximum TOF of 507 at 20 mL/min H 2 flow, but can be recycled 4 times (9 times at 8 mL/min H 2 flow). Ethyl acetate is a better organic phase solvent compared to dichloromethane and chlorobenzene in terms of TOF and recyclability. All of the NPs studied show > 80 % selectivity for the isomer product (propanal). The branched, open structure of the glutathione and use of the biphasic solvent provides high catalytic activity, high selectivity, and easy removal of the products in the organic phase for good recyclability of the water-soluble catalysts.[a] Dr.
This work presents a general method of using iodine to partially remove thiolate ligands from metal clusters, resulting in significant catalytic enhancement.
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