Simultaneous Detection of Circularly Polarized Luminescence and Raman Optical Activity in an Organic Molecular Lemniscate

Circularly polarized luminescence (CPL) and Raman optical activity (ROA) were observed in a single spectroscopic experiment for a purely organic molecule, an event that had so far been limited to lanthanide‐based complexes. The present observation was achieved for [16]cycloparaphenylene lemniscate, a double macrocycle constrained by a rigid 9,9′‐bicarbazole subunit, which introduces a chirality source and allows the molecule to be resolved into two configurationally stable enantiomers. Distortion of oligophenylene loops in this lemniscular structure produces a large magnetic transition dipole moment while maintaining the π‐conjugation‐induced enhancement of the Raman signal, causing the appearance of the CPL/ROA couple. A two‐photon mechanism is proposed to explain the population of the lowest‐energy excited electronic state prior to the simultaneous emission‐scattering event.