Non‐Covalent Chemistry on Surface‐Confined, Isolated Dendrimers

A “bottom‐up” fabrication of nanometer‐scale dendritic structures via the growth of isolated, nanosized supramolecular structures on gold surfaces is presented. A novel dendritic wedge containing peripheral pyridines and a focal dialkylsulfide chain ( 9 ) was synthesized and its coordination chemistry in solution was tested with a second‐generation Fréchet dendron functionalized with a focal SCS Pd II pincer moiety ( 13 ). Replacement of the labile acetonitrile in 13 by the pyridine groups of 9 converts dendritic wedge 9 into fourth‐generation metallodendron 9  ·  13 4 in one step. Based on these results the spatially confined growth on a gold surface was studied. The dendritic molecules with reactive pyridine groups at the periphery ( 9 ) were first spatially isolated by inserting them into decanethiol self‐assembled monolayers (SAMs) on a gold surface. Subsequently, the peripheral pyridines were reacted via metal–ligand coordinative interactions by exposing the monolayer to a solution of dendritic wedges containing focal SCS Pd II pincer moieties ( 13 ). The isolated molecules inserted into the original SAM in the first step were resolved by ex‐situ tapping‐mode atomic force microscopy (TM‐AFM). The subsequent Pd II –pyridine coordination resulted in a significant increase in size of the individually resolved molecules. Reference experiments demonstrated that the increased size of the isolated dendrimers on the gold substrate was a result of specific metal–ligand interactions. The methodology presented herein allows the creation of surface‐confined architectures and potentially provides a viable complement to currently employed “top‐down” methods in nanofabrication.