Tuning Intramolecular Förster Resonance Energy Transfer and Activating Intramolecular Singlet Fission

: The synergy of panchromatic absorption throughout most of the visible range of the solar spectrum and intramolecular singlet fission (SF) has been realized in a series of conjugates featuring different light-harvesting subphthalocyanines (SubPcs) and an energy accepting pentacene dimer (Pnc2 ). At the focal point was a modular SubPc approach, which was based on decorating the SubPc core with different peripheral substituents to tailor and fine-tune their optical properties. Transient absorption measurements assisted in corroborating that the SubPcs act as energy-transfer antennas by means of unidirectional and quantitative intramolecular Forster resonance energy transfer (FRET) to the Pnc2 , where an intramolecular SF affords triplet quantum yields reaching unity.