Circularly Polarized Light-Regulable Crystal–Liquid Phase Transition of Self-Assembled Macroscopic Chiral Twisted Ribbons

Chirality is a fundamental property of nature, observed
at the
subatomic, molecular, supramolecular, and macroscopic levels. Circularly
polarized light (CPL) has attracted extensive attention as an effective
tool for regulating and inducing chirality on various scales. Herein,
we report the formation of micron-scale twisted ribbons from homochiral
molecular H8-BAz through self-assembly driven by solvophobic
interactions. The chiral information in H8-BAz is effectively
transferred and amplified in the supramolecular structure and finally
appears as macroscopic homochiral twisted ribbons that match the chirality
of the monomers. The ribbons undergo a photoinduced crystal-to-liquid
transition (PCLT) when exposed to 365 nm light due to the isomerization
of the azobenzene structure. Additionally, the PCLT behavior of chiral
ribbons is regulated by CPL: When irradiated with homochiral right-handed
CPL (RCP), the ribbon with a P-helix formed by (R)-H8-BAz undergoes a faster phase transition.
The M-helix ribbon undergoes a faster phase transition
with left-handed CPL (LCP). The average time difference for the phase
transition reaches 1.5 times. Our results demonstrate a simple method
for creating macroscopic chiral structures and the impact of chiral
light sources on their phase transition process.