Dual space-conjugated pyrene-based ketone exhibits dual state-tuned emission wavelengths and enhanced circularly polarized luminescence

Abstract

This study presents the development of chiral naphthalene-based diketone luminescent materials, specifically BiPyCO. The product exhibits excellent dual-state emission with largely distinct wavelengths. It was characterized by predominant locally excited (LE) emission in acetonitrile, alongside a weak shoulder peak attributed to through-space conjugated (TSC) excitons. A significant red shift of up to 93 nm in the aggregated state was observed, indicating the tunability of the emission wavelength through state changes. Chiroptical studies reveal excellent chiral induction in excited states. In solution, while LE emission lacks a circularly polarized luminescence (CPL) response, TSC excitons exhibit significant mirror signals for (R)-/(S)-BiPyCO, showing a high emission dissymmetry factor of 0.01 for the single molecule system. X-ray crystallography confirms the presence of dual TSC interactions. Furthermore, theoretical calculations and weak interaction analysis highlight significant spatial conjugation between pyrene and naphthyl units. This research offers valuable insights into designing chiral materials with tunable luminescence and enhanced CPL response.