Circularly Polarized Luminescence (CPL) from Pyrene‐Appended Cyclohexanediamides and Photoirradiation‐Tuned CPL Inversion

AbstractCircularly polarized luminescence (CPL) has been achieved in various chiral molecules and self‐assembled systems, but it remains a challenge to modulate CPL signals. To address this issue, a pair of enantiomeric pyrene‐appended cyclohexanediamide derivatives S,S/R,R‐CHPA with a V‐shaped conformation was designed and their CPL generation and photo‐response were investigated. Owing to the peculiar spatial location of the two pyrene segments in each molecule, CHPA emitted strong circularly polarized excimer emission (CPEE) with a |glum|value up to 1.49×10−2. Due to the presence of the vinylene groups, the optical properties could be regulated by UV light. It was found that under 365 nm irradiation, the absorption and emission bands of CHPA exhibited a pronounced hypochromatic shift, and the bluish white fluorescence gradually turned into dark blue. More intriguingly, these spectral changes were accompanied by a chirality inversion both in the ground and excited states as demonstrated by CD and CPL spectra, which could be attributed to the photoinduced E–Z isomerization of the vinylene groups. This work provides an extraordinary example in which the CPL signal of a single organic molecule could be efficiently inverted.