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

The synthesis of surface-confined, nanometer-sized dendrimers and Au nanopa rticles was performed starting from single Pd-II pincer adsorbate molecules (10) embedded as isolated species into 11-mercapto-1-undecanol and decanet hiol self-assembled monolayers (SAMs) on gold. The coordination of monolaye r-protected Au nanoclusters (MPCs) bearing phosphine moieties at the periph ery (13), or dendritic wedges (8) having a phosphine group at the focal poi nt, to SAMs containing individual Pd-II pincer molecules was monitored by t apping mode atomic force microscopy (TM AFM). The individual Pd-II pincer m olecules embedded in the decanethiol SAM were visualized by their coordinat ion to phosphine MPCs 13; isolated objects with a height of 3.5 +/- 0.7 nm were observed by TM AFM. Reaction of these embedded Pd-II pincer molecules with the dendritic wedge 8 yielded individual molecules with a height of 4. 3 +/- 0.2 nm.