Surface Engineering Assisted Size and Structure Modulation of Gold Nanoclusters by Ionic Liquid Cations

Abstract

Surface modification induced core size/structure change is a recent discovery in inorganic nanoparticles research, and has rarely been revealed at the molecular level. Here, we exemplify with atomically precise Au nanoclusters (NCs) that proper surface modification can selectively stabilize the desired Au⁰ core, conducive to the formation of size/structure-controlled Au NCs. Leveraging π-π enhanced ion-pairing interactions, ionic liquid (IL) cations are bonded to Au^I -thiolate complexes. The hydrophobic-hydrophobic interactions between IL cations subsequently provide a good mechanism to prolong the size of the Au^I -thiolate complexes, selectively producing small-sized Au NCs upon reduction. Through combined control over the structure and concentration of IL cations, pH and solvent polarity, we are able to produce atomically precise Au NCs with customizable size, atomic packing structure, and surface chemistry. This work also provides a facile means to integrate/synergize the materials functionalities of Au NCs and ILs, increasing their acceptance in diverse fields.

Keywords: Atomic precision; Gold nanoclusters; Ionic liquids; Structure modulation; Surface engineering.