Amplification of local chirality within a folded dendrimer. An intramolecular ‘sergeants and soldiers’ experiment

Abstract

A series of pyridine-2,6-dicarboxamide dendrons having varying proportions of chiral and achiral termini have been prepared. Circular dichroism and X-ray crystallographic studies indicate that these folded dendrons propagate terminal chirality via a ‘sergeants and soldiers’ process. The extent of chiral amplification shows a dependence on dendron generation, but also is affected by the relative positioning of the chiral termini at the periphery of the dendron. Analysis of the crystal structures of the G1 dendrons, 4a – 6a , reveals chain–chain and chain–dendron conformational communication, which is likely to be responsible for the chiral amplification observed in solution.