Simultaneous Detection of Circularly Polarized Luminescence and Raman Optical Activity in an Organic Molecular Lemniscate
Résumé
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 pi-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.
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Angew%20Chem%20Int%20Ed%20-%202022%20-%20Palomo%20-%20Simultaneous%20Detection%20of%20Circularly%20Polarized%20Luminescence%20and%20Raman%20Optical%20Activity.pdf (5.11 Mo)
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