LAUSR

Herein we disclose methods that greatly improve the solution- and gas-phase handling properties of larger aqueous-phase gold–thiolate clusters, which previously presented extreme technical obstacles to molecular analysis and size control, even as they have enjoyed ever-wider applications in materials science and biomedicine. The methods are based upon an analogy between the polyacidic surface structure of the pMBA-protected clusters (pMBA = p-mercaptobenzoic acid) and that of oligonucleotides. A volatile ion-pairing reagent, TEA = triethylamine, greatly improves solution-phase stability near neutral pH and thus facilitates both electrospray generation of the gas-phase ions and the in-line reversed-phase ion-pairing HPLC-ESI-MS approach to analyzing complex mixtures of Au-pMBA oligomers and clusters. Previously anticipated but never established compounds, including Au36(pMBA)24, are thereby demonstrated. These results are in accord with recent theoretical simulations of ion pairing of model Au144(pMBA)60 c...