We
report the synthesis of one-dimensional supramolecular polymers
composed of one-handed helical macromolecules bearing fluorescent
pendant groups and the generation of circularly polarized light on
the basis of hierarchical chiral amplification starting from a tiny
amount of chiral substituent. Copolymerization of benzo[1,2-b:4,5-b′]dithiophene-appended achiral/chiral
isocyanides (99:1, mol/mol) with a solid-state photoluminescence feature
afforded submicrometer supramolecular fibers, in which almost perfect
single-handed helical polyisocyanides were noncovalently connected
end to end. The resulting helical supramolecular polymers were further
helically assembled to form a cholesteric liquid crystal film with
an intense circularly polarized luminescence (CPL) signal. Surprisingly,
the supramolecular system containing only 0.01 mol % of the chiral
monomer unit also emitted the observable circularly polarized light
owing to multiple chiral amplification from an infinitesimal point
chirality to helical chirality and then to supramolecular chirality.
Furthermore, chiral information was efficiently transferred from the
helically assembled supramolecular system containing 1 mol % of the
chiral unit to achiral dye molecules blended in the film, allowing
full-color tunable induced CPL with luminescence dissymmetry factors
greater than 1.0 × 10–2. This unprecedentedly
strong chiral amplification enables the creation of helical supramolecular
polymers and chirally assembled systems with various chiral functions
based solely on an infinitesimal chiral source.
We have succeeded in the helicity control of polymer backbones and their circularly polarized luminescence without the need for chirality of an unnatural antipode, l-glucose.
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