Head to Tail Distortion Wave Characterizes the Enantiomerization of Helicenes

A fresh look on helicenes’
enantiomerization process with
a focus on ring conformation reveals that it can be described as a
step-by-step mechanism in which maximal distortion is consecutively
transferred along the helicene skeleton, head to tail. Density functional
theory methods were used to compute the enantiomerization pathway,
and continuous symmetry measures were applied to quantify the distortion
of even-number helicenes with 8–14 rings. Our findings show
that the distortion wave is additivethe process always starts
from one edge of the helicene and progresses along the rings until
the other edge is reached. As more rings are added to the helicene,
extra steps are appended to the distortion wave. Implications of this
fundamental process are discussed in light of similar natural phenomena
from polymer dynamics to snake locomotion.