Tunable Aminooxy‐Functionalized Monolayer‐Protected Gold Clusters for Nonpolar and Aqueous Oximation Reactions

Abstract

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.

Effect of Size, Coverage, and Dispersity on the Potential-Controlled Ostwald Ripening of Metal Nanoparticles

“…However, THPC-coated, 1.6 nm-diameter Au NPs did not show a plasmon band over this wavelength range. This indicates the smaller size since it is widely known that the LSPR band disappears for NPs of ∼2 nm in diameter or smaller. ,, …”

“…This indicates the smaller size since it is widely known that the LSPR band disappears for NPs of ∼2 nm in diameter or smaller. 38,44,49 Microscopic Characterization of Au NPs. The as-synthesized Au NPs were attached to (3-aminopropyl)triethoxysilane (APTES)functionalized glass/ITO (glass/ITO/APTES) electrodes by directly soaking the electrodes into solutions of NPs.…”

Electrooxidation, Size Stability, and Electrocatalytic Activity of 0.9 nm Diameter Gold Nanoclusters Coated with a Weak Stabilizer

“…Some of the major challenges in this area of research are: 1) the synthesis of uniform NCs with an appropriate ligand stabilizer that provides good size stability in solution, 2) the ability to attach the NCs to an electrode or other support surface, and 3) the use of a stabilizer with weak enough interactions with the metal NC to allow for high surface metal activity. In most cases, small Au NCs have been stabilized with thiolate ligands . Thiolate ligands bridge Au atoms and lift them out of the cluster surface to form strong (RS‐(Au−SR)n) staple motifs .…”

“…In most cases, small Au NCs have been stabilized with thiolate ligands. [22][23][24] Thiolate ligands bridge Au atoms and lift them out of the cluster surface to form strong (RS-(AuÀ SR)n) staple motifs. [25] Chen and coworkers synthesized glutathionecoated Au NCs for use as photosensitizers, for example.…”

Electrochemical determination of surface area-to-volume ratio for metal nanoparticle analysis.

“…The LSPR peak shifted positive with increasing NS diameter, consistent with their size from 4 nm diameter to 70 nm diameter, 112 while the 1.6 nm diameter Au NSs sample showed no prominent LSPR peak as expected for this size. 178,190 We attached 4 nm to 70 nm diameter Au NSs to aminopropyltriethoxy silane (APTES)functionalized glass/ITO electrodes and to APTES-functionalized SiO2-coated Au TEM grids for SEM and TEM measurements, respectively. Ivanova and co-workers previously showed that the peak oxidation potential (Ep,ox)…”