Switching of chiral induction in helical aromatic oligoamides using solid state-solution state equilibrium.

The introduction of an R asymmetric center in an aromatic oligoamide that adopts stable helical conformations leads to a significant shift of the equilibrium between the right-handed and left-handed helices in solution: the R-P and R-M helices are diastereoisomers. However, these two species were found to cocrystallize in 1:1 proportions. Thus the chiral induction observed in solution is switched off in the solid state. This phenomenon represents an original and unexpected means to control handedness in helical oligomers.