|One step beyond a dendrimer is a Sierpinski triangle. Imagine a first-generation dendrimer with each extending unit having three arms and then close the edges. Synthesizing a molecule based on this concept may seem a mission impossible but the George R. Newkome team (of dendrimer fame) has reported they pulled it off (Sarkar et al. DOI). Even in a one-step reaction by self-assembly. |
The precise procedure involved reacting a 1:1 mixture of two particular terpyridine units, one K-shaped and one V-shaped, in a methanol solution of a cadmium salt. Adding hexafluorophosphate after 30 minutes made sure the cadmium ions are countered by PF6-. Yield 95%. As evidence for the purity the methoxy groups showed up at the expected places in the correct ratio in NMR. Furthermore the blobs visible on the TEM image have the correct dimensions and even hint at triangles. Sierpinski triangles made easy!