Poly(ethylene glycol) Ligands for High-Resolution Nanoparticle Mass Spectrometry

Abstract

Measurements of the core and ligand monolayer compositions of small gold nanoparticles (NPs) using electrospray ionization (ESI) mass spectrometry were performed by incorporating ionization tags, methoxy penta(ethylene glycol) thiolate ligands (-S-PEG), into the ligand monolayers via ligand exchange. During ESI, alkali metal ions (M+) coordinate to the -S-PEG ligands and give the NPs positive charge. Atomically precise, high-resolution measurements show unequivocally that the NP composition is Au25(ligand)18. The predominant ions, M4Au25(ligand)18 3+ and M5Au25(ligand)18 4+, have 1− charge on the core. Because ligand exchange is a statistical process, there is a distribution of mixed-monolayer exchange products, which is reflected in the mass spectra.

Oxygen Electroreduction Catalyzed by Gold Nanoclusters: Strong Core Size Effects

“…[23] In It should be noted that these mass spectrometric profiles are all consistent with previous studies in the quantitative determination of gold nanocluster core dimensions. [16,[18][19][20]22] UV/Vis absorption spectroscopy measurements further confirmed the variation of the nanocluster core size ( Figure S1 in the Supporting Information).…”

Toward the Creation of Functionalized Metal Nanoclusters and Highly Active Photocatalytic Materials Using Thiolate-Protected Magic Gold Clusters

“…This causes a change in solubility and differently sized Au n (SR) m clusters can therefore be separated using different solvents. 52,53,5658 The high-resolution separation of Au n (SR) m clusters by solvent extraction becomes difficult for large cluster sizes because the difference in surface polarity decreases for each cluster size. This method can also not separate clusters doped with various heteroatoms depending on the number of doped atoms.…”

Blue Luminescence Emitted from Monodisperse Thiolate‐Capped Au11 Clusters

“…ESI-MS is a soft ionization technique and a minimally fragmenting tool to investigate biological molecules and noncovalent interactions, [23] and can provide the composition of gold clusters with atomic precision. [24] Figure 3 represents the mass spectrum of the as-prepared gold clusters performed in the positive ion mode. There are two intense peaks observed, m/z 467.6 and m/z 968.0, which correspond to the tetraoctylammonium cation (TOA…”