Thermally Switchable Fluorescence Resonance Energy Transfer via Reversible Diels–Alder Reaction of π‐Conjugated Oligo‐(Phenylene Ethynylene)s

The combination of reversible, dynamic covalent bonds and π-conjugated oligo-(phenylene ethynylene)s is utilized for exchange reactions between two acceptors and one donor containing copolymer in the solid state upon thermal treatment. The specific molecular design of the polymers allows upon thermally triggering the reshuffling of the π-conjugated donor and acceptor moieties. Depending on the nature of the acceptor, an increased and a decreased fluorescence resonance energy transfer (FRET), respectively, can be observed for the mixing of the copolymers or the demixing of a donor-acceptor copolymer.