Chemistry on surface-confined molecules: an approach to anchor isolated functional units to surfaces

The synthesis of surface-confined, nanometer-sized dendrimers and Au nanoparticles was performed starting from single PdII pincer adsorbate molecules (10) embedded as isolated species into 11-mercapto-1-undecanol and decanethiol self-assembled monolayers (SAMs) on gold. The coordination of monolayer-protected Au nanoclusters (MPCs) bearing phosphine moieties at the periphery (13), or dendritic wedges (8) having a phosphine group at the focal point, to SAMs containing individual PdII pincer molecules was monitored by tapping mode atomic force microscopy (TM AFM). The individual PdII pincer molecules embedded in the decanethiol SAM were visualized by their coordination to phosphine MPCs 13; isolated objects with a height of 3.5 ± 0.7 nm were observed by TM AFM. Reaction of these embedded PdII pincer molecules with the dendritic wedge 8 yielded individual molecules with a height of 4.3 ± 0.2 nm.