Modulation of circularly polarized luminescence through excited-state symmetry breaking and interbranched exciton coupling in helical push-pull organic systems.

π-Helical push-pull dyes were prepared and their (chir)optical properties were investigated both experimentally and computationally. Specific fluorescent behaviour of bis-substituted system was observed with unprecedented solvent effect on the intensity of circularly polarized luminescence (CPL, dissymmetry factor decreasing from 10 to 10 with an increase in solvent polarity) that was linked to a change in symmetry of chiral excited state and suppression of interbranched exciton coupling. The results highlight the potential of CPL spectroscopy to study and provide a deeper understanding of electronic photophysical processes in chiral π-conjugated molecules.