Significantly Boosted and Inversed Circularly Polarized Luminescence from Photogenerated Radical Anions in Dipeptide Naphthalenediimide Assemblies

Circularly polarized luminescence (CPL) reflects the excited-state properties of the chiral system. However, compared to the singlet and triplet excited states, there are still many unknowns about CPL from the double excited state. Here, using the self-assembly strategy of a dipeptide substituted naphthalenediimide (NDI-GE) and the photogenerated radical anions, we have explored the ground-state (CD) and excited-state (CPL) chiral characteristics of neutral NDI and NDI center dot- radical anion assemblies. The neutral gelator assemblies showed CPL with the dissymmetry factor g(lum) on the order of 10(-3); the radical anion exhibited an inversed CPL signal with a significantly enhanced g(lum) of 10(-1). Time-dependent density functional theory calculation revealed that upon formation of the radical anions, the direction of the dipole moment changed, thus leading to the inversion of CD and CPL. The present work reveals a new platform for developing CPL materials based on the doublet excited state.