Illuminating Olympicenes: Insights Into Anti-Kasha Photophysics in Polycyclic Aromatic Hydrocarbons.

Abstract

Olympicene, or 6H-benzo[cd]pyrene, is a polycyclic aromatic hydrocarbon (PAH) with five fused six-membered rings arranged in a pattern reminiscent of the Olympic symbol. While functionalized olympicene-based materials have captivated attention for their unique graphene-fragment topology and aromaticity, their photoluminescent properties remain virtually unexplored. Here, we synthesize olympicene-core functionalized derivatives and report their "anomalous" photophysical properties. These olympicene derivatives display extensive vibronic structure and highly interacting electronic states. Such effects give rise to excited-state dynamics that are rare and unconventional in small PAH systems. Specifically, these olympicene derivatives exhibit dual fluorescence upon photoexcitation, accompanied by pronounced excitation-dependent emission behavior. Spectroscopic evidence demonstrates these behaviors arise from multiple singlet emissive states-an anti-Kasha locally excited (LE) state (S_n, n ≥ 2) and an intramolecular charge transfer (ICT) state. This work positions olympicene-functionalized derivatives as a new platform to study fundamental photophysics. Exploring these properties will lead to new and advanced optoelectronic applications.