Electrospray ionization mass spectrometry is employed to study the formation of L3- and L5-protected gold clusters (L3 = 1,3-Bis(diphenylphosphino)propane; L5 = 1,5-Bis(diphenylphosphino)pentane), and it is found that molecular complexes in which Au+ is bound to at least one triphenylphosphine ligand (PPh3) act as precursors, while complexes in which Au+ is bound only to the bidentate diphosphine ligands act as reaction bottlenecks. Ligand exchange mechanisms and ion equilibria were established in the absence of a reducing agent, and a critical reaction was modeled with ab initio molecular dynamics simulations. The displacement of one PPh3 by L3 on [Au(PPh3)2]+ was studied with Car Parrinello molecular dynamics and transition path sampling. It is found that experiment and theory converge on a complete description of a reaction event critical in the synthesis of a particular set of monolayer protected nanoparticles.
Citation: Journal of Physical Chemistry C
Pub Type: Journals
Electrospray ionization, gold nanoparticle, Car-Parrinello molecular dynamics, monolayer protected gold cluster