Aurophilic Interactions in the Self-Assembly of Gold Nanoclusters into Nanoribbons with Enhanced Luminescence

Aurophilic interactions ((AuAuI)-Au-I) are crucial in directing the supramolecular self-assembly of many gold(I) compounds; however, this intriguing chemistry has been rarely explored for the self-assembly of nanoscale building blocks. Herein, we report on studies on aurophilic interactions in the structure-directed self-assembly of ultrasmall gold nanoparticles or nanoclusters (NCs, <2 nm) using [Au-25(SR)(18)](-) (SR=thiolate ligand) as a model cluster. The self-assembly of NCs is initiated by surface-motif reconstruction of [Au-25(SR)(18)](-) from short SR-[Au-I-SR](2) units to long SR-[Au-I-SR](x) (x>2) staples accompanied by structure modification of the intrinsic Au-13 kernel. Such motif reconstruction increases the content of Au-I species in the protecting shell of Au NCs, providing the structural basis for directed aurophilic interactions, which promote the self-assembly of Au NCs into well-defined nanoribbons in solution. More interestingly, the compact structure and effective aurophilic interactions in the nanoribbons significantly enhance the luminescence intensity of Au NCs with an absolute quantum yield of 6.2 % at room temperature.