Subnanometer gold clusters have been shown to exhibit surprising catalytic activity due to their highly size-dependent properties which are distinct from larger nanoparticles and bulk surfaces. In this size-regime where “each-atom-counts” toward the properties of clusters it is necessary to develop scalable solution-phase methods for synthesizing clusters with predetermined size and composition. While phosphines have been employed for decades to promote the synthesis of gold clusters, it is still not understood how the presence of different functional groups at phosphine centers influences the size and properties of ligated gold clusters. We are characterizing the electronic and steric effects of differently-substituted phosphines on the distribution of gold cluster ions synthesized in solution using high-resolution analytical electrospray ionization mass spectrometry (ESI-MS) and collision induced dissociation (CID). Quantitative ligand binding and cluster fragmentation energies, which influence the stability and size evolution of clusters, are also being measured using surface induced dissociation (SID) in a custom-built Fourier Transform Ion Cyclotron Resonance Mass Spectrometer (FT-ICR-MS). The results of Rice-Ramsperger-Kassel-Marcus (RRKM) based modeling of the SID data are compared to ligand binding energies determined using high-level theoretical calculations. In addition, the surface immobilization and charge reduction of ligated cluster ions, which are known to determine their properties, are being explored using soft landing of mass-selected ions (SL) in a novel cluster-deposition system. This multifaceted mass-spectrometry approach enables characterization of a wide range of relevant phenomena including synthesis, thermochemistry, surface immobilization, and reactivity. The understanding obtained from this work will aid the directed synthesis of clusters and with predetermined properties for catalytic applications. <br/>

Influence of phosphine substitution on the synthesis and properties of gold clusters

254th National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.