Super Chirality Promotion of Helical Poly(Phenyl Isocyanide)s by Grafting onto Ethyl Cellulose

Chiral property of cellulose can be transferred to final materials, here artificial helical polymer, right-handed helical poly(phenyl isocyanide) (PPI) is grafted onto ethyl cellulose (EC) with expecting to enhance the chiral effect of PPI. EC-2,3-g-PPI_n copolymers are prepared via “click” chemistry of copper-catalyzed alkyne-azide cycloaddition, and confirmed by high-resolution ¹H and ¹³C NMR, Fourier transform infrared spectroscopy (FTIR), and gel permeation chromatography (GPC). The resulting EC-2,3-g-PPI_n copolymer takes a right-handed helical structure with super circular dichroism intensity which is 302% higher than that of PPI, which indicates that EC backbone promotes the right-handed chirality of PPI_n. Furthermore, EC-2,3-g-PPI_n exhibits good chiral recognition ability of the D/L-Ala-DNSP fluorescent probe, and induces a uniquely visible blue shift for L-Ala-DNSP. Therefore, a novel facile strategy is provided to highly improve chiral property and chiral recognition ability of artificial helical polymers by grafting onto EC.