Thiol protected gold clusters are self-assembled systems formed by Au(0) core and a protecting monolayer made of thiol molecules. The latter is the principal responsible of their chemical behavior and their interaction with the environment. Understanding the parameters that influence the stability and reactivity of the monolayer will enable its precise and controlled functionalization. Here we present a protocol for the investigation of the monolayer reactivity in Au25(SR)18 based on MALDI mass spectrometry and NMR spectroscopy. Thiol exchange reaction between cluster and thiol molecules has been investigated showing how this reaction is affected by the thiol affinity for Au25. Furthermore, inter-cluster thiol exchange has been clarified for the first time to occur during collisions between particles without thiol-release to the solution. Importantly, the rate of direct thiol exchange between clusters is comparable to the one for ligand exchange with free thiols. However, the thermodynamic driving force of the two reactions is different, since only the latter involves free thiol species.

Dynamic nature of thiolate monolayer in Au25(SR)18 nanoclusters

255th National Meeting (2018)

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