Effect of copolymer composition in poly(N-propargylamide) on helical structure and optical activity

Homo- and co-polymerizations of a chiral N-propargylamide (M1 containing 2,2-dimethyl-5-oxo-1,3-dioxolane group) and an achiral N-propargylamide (M2 containing adamantane group) were carried out in the presence of (nbd)Rh+B−(C6H5)4. All the (co)polymers synthesized were obtained in a yield ⩾80%. Poly(1) assumed helices of a predominant handedness and exhibited an optical activity, while poly(2) formed helices of an equal amount of right- and left-handed screws and showed no optical activity. The maximum wavelength and CD signal intensity of the copolymers with varied M1/M2 ratios demonstrated considerable composition dependence. This observation was explained by the synergic effects between the pendent groups during the formation of helical structures.