Light‐Harvesting Supramolecular Polymers: Energy Transfer to Various Polyaromatic Acceptors

A supramolecular light-harvesting antenna consisting of 3,6-disubstituted phosphodiester-linked phenanthrene trimers (donors) was doped with different charged and uncharged polyaromatic and heteroaromatic acceptor chromophores. Excitation of the phenanthrene moieties is followed by energy transfer to the acceptor molecules and radiative relaxation. The self-assembled fiber structure of the phenanthrene trimers is not altered by the dopant, as verified by atomic force microscopy (AFM). Among several neutral and cationic acceptor chromophores, benzo(a)pyrene emerged as one of the highest fluorescence quantum yields, reaching 31 % at a chromophore/phenanthrene ratio of 12 mol-%. The energy transfer is probably a combination of Forster resonance energy transfer (FRET) and a coherent energy transfer mechanism.