Conformational Landscapes in the Ground and Excited States Dictate Circularly Polarized Excimer Emission: A Thermodynamic–Kinetic Interplay in Carbazole Dimer Systems

We demonstrate that in chiral carbazole dimers, the tt conformer generates intense excimer CPL, while gauche rotamers yield only local emission. In 1a, CPL intensifies and red-shifts upon cooling due to greater tt contribution. In contrast, the tert-butyl derivative 1b shows weak, temperature-insensitive CPL owing to enhanced accessibility of non-CPL-emissive gauche conformers. This work reveals how subtle substituent and environmental effects modulate excited-state conformational dynamics and chiroptical responses through a thermodynamic-kinetic interplay.