Peptide Magic: Interdistance-Sensitive Sign Inversion of Excimer Circularly Polarized Luminescence in Bipyrenyl Oligopeptides

We prepared 16 novel chiral peptide–pyrene organic luminophores with different distances between the fluorescent pyrene groups and investigated their properties in CHCl3 at room temperature. The peptide–pyrene organic luminophores bearing two pyrene groups emit strong excimer circularly polarized luminescence (CPL) in the solution state. Two pendant pyrenyl groups in a series of chiral oligopeptides clearly revealed excimer CPL in chloroform at 480–490 nm (|gem| ≈ (2–8) × 10–3). When the distance between the two pyrenes increased, the sign of the CPL signals was inverted twice, while the sign of the corresponding circular dichroism (CD) signals was retained, (|gCD| ≈ (3–8) × 10–5).