Isomeric decker metallo-supramolecules with tunable luminescence and chiroptical properties

Abstract

The regulation of interchromophoric interactions in multichromophoric systems is crucial for developing high-performance photofunctional materials. In this study, we present a novel self-assembly strategy to construct isomeric decker complexes, denoted as S1 and S2, which integrate disparate chromophores, achiral BODIPY and chiral binaphthyl moieties. This isomerization results in distinct chromophore packing modes. In the case of S1, the BODIPY and binaphthyl moieties are arranged in a relatively loose manner (∼6.0 Å), enabling efficient FRET and preserving the strong locally excited (LE) emission (Φ_F = 91.3%) characteristic of the BODIPY unit. In contrast, for S2, the denser packing between the BODIPY and binaphthyl moieties (∼4.8 Å) leads to through-space charge transfer (TSCT) and weak charge transfer (CT) emissions (Φ_F = 8.6%). Notably, only complex (R)/(S)-S1 shows mirror-image circular dichroism (CD) signals based on chirality transfer and circularly polarized luminescence (CPL), as supported by TD-DFT calculations, which reveal that the binaphthyl moiety alters the angle between the electric transition dipole moment (μ) and the magnetic transition dipole moment (m).