Isotopic Exchange of Atomically Precise Nanoclusters with Materials of Varying Dimensions: From Nanoscale to Bulk

We present isotopic exchange reactions of atomically precise silver nanoclusters (NCs) with materials of different dimensions, namely, NCs, plasmonic nanoparticles (NPs), and bulk metals, all made of silver. Isotopically pure 109Ag25(DMBT)18- and 107Ag25(DMBT)18- (DMBT is 2,4-dimethyl benzene thiol) were reacted with Ag NPs of different sizes in the range of ∼2-11 nm, protected with the same ligand. The exchange of 107Ag/109Ag atoms in the NC was monitored using electrospray ionization mass spectrometry. The reaction kinetics was analyzed by fitting the temporal evolution of the reactant concentration to a kinetic model. The reaction timescales of NC-NP reactions were significantly longer compared to those of the NC-NC exchange process under similar conditions. Differences between NC-NC exchange and NC-NP exchange highlighted the importance of the structure in controlling the reaction. Moreover, isotopic exchanges of the NC were also studied with the bulk metal to obtain a complete understanding of how the kinetics of atom transfer varies upon changing the size of the reacting partner from nanoscale to bulk.