Figure 7 . Changes in CD and UV-vis spectra of the composite
films, consisting of L-Glu/PMMAzo-1 (1/1, w/w, red line) and
D-Glu/PMMAzo-1 (1/1, w/w, blue line) without annealing.
Recently, achiral side-chain Azo units in polymers are found to assembly
into π-π stacking structures with the help of the chiral induction by
limonene.35 In this system, we propose that the C-H/π
interaction between cellulose and Azo units may be one of the factors
promoting the occurrence of chirality transfer. In order to further
reveal the mechanism of the chiral induction process, the repeating unit
of CTA, permethylated D-Glu and L-Glu, were synthesized to simplify the
induction system to further verify the conjecture. By utilizing D-Glu
and L-Glu as optical antipodes, we performed the chiral induction
process of achiral PMMAzo-1 in the same manner as CABu. As shown in
Figure 7, the CD spectra of Glu/PMMAzo-1 composite films showed a
intense and mirror-image bisignate Cotton effect. The induction of D-Glu
made the polymer film exhibit a negative CD signal, opposite to the
effect of L-Glu. The results demonstrated that the supramolecular
chirality of the achiral side-chain PMMAzo-1 polymer on thin films could
be successfully induced by the one of the most widely distributed and
important monosaccharides in nature.