Isolation and Total Structure Determination of an All-Alkynyl-Protected Gold Nanocluster Au144

Abstract

Total structure determination of a ligand-protected gold nanocluster, Au₁₄₄ , has been successfully carried out. The composition of title nanocluster is Au₁₄₄ (C≡CAr)₆₀ (1; Ar=2-FC₆ H₄ -). The cluster 1 exhibits a quasi-spherical Russian doll-like architecture, comprising a Au₅₄ two-shelled Mackay icosahedron (Au₁₂ @Au₄₂ ), which is further enclosed by a Au₆₀ anti-Mackay icosahedral shell. The Au₁₁₄ kernel is enwrapped by thirty linear ArC≡C-Au-C≡CAr staple motifs. The absorption spectrum of 1 shows two bands at 560 and 620 nm. This spectrum is distinctly different from that of thiolated Au₁₄₄ , which was predicted to have an almost identical metal kernel and very similar ligands arrangement in 1. These facts indicate the molecule-like behavior of 1 and significant involvement of ligands in the electronic structure of 1. The cluster 1 is hitherto the largest coinage metal nanocluster with atomically precise molecular structure in the alkynyl family. The work not only addresses the concern of structural information of Au₁₄₄ , which had been long-pursued, but also provides an interesting example showing ligand effects on the optical properties of ligand protected metal nanoclusters.

Keywords: alkynyl ligands; cluster compounds; gold; nanostructures; optical properties.