Alkyne-Monofunctionalized Gold Nanoparticles as Massive Molecular Building Blocks

Using a tripodal, thioether-based ligand comprising a remote protected acetylene, we efficiently stabilize small gold nanoparticles (Ø ≈ 1.2 nm) which are isolated and purified by chromatography. The 1:1 ligand-to-particle ratio is obtained by comparing the particles' dimensions measured by transmission electron microscopy with the weight fraction of the coating ligand determined by thermogravimetric analysis. The single ligand coating of the gold particle guarantees the presence of a single masked alkyne per particle. It can be addressed by wet chemical protocols providing the particles with the properties of “massive molecules”. The “massive molecule” nature of the particles is demonstrated by involving them in wet chemical coupling protocols like oxidative acetylene coupling providing gold nanoparticle dimers (34 % isolated yield) or alkyne-azide “click”-chemistry with a suitable triazide, giving trimeric particle architectures (30 % determined by transmission electron microscopy). The particle stabilization obtained by the coating ligand allows, for the first time, to treat these multi-particle architectures by size exclusion chromatography.