Gigantic chiroptical enhancements in polyfluorene copolymers bearing bulky neomenthyl groups: importance of alternating sequences of chiral and achiral fluorene units

An alternating copolymer consisting of achiral and chiral units emits remarkably efficient CPL on photo-excitation. The main-chain twist bias is enhanced by thermal annealing by the factor of 10(4) in the ground state. An anisotropy factor of the polymer in the excited state is greater by approximately an order of magnitude compared with that in the ground sate.