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.