Coronene Bisimide as a Visible‐Light‐Mediated Triplet‐Triplet Energy Transfer Catalyst

Abstract Photosensitization has emerged as a versatile tool to facilitate access to excited states under mild conditions, allowing for efficient and selective photochemical transformations. Herein, we report a very simple molecule, coronene bisimide (CBI), as a potent visible‐light photosensitizer featuring a high extinction coefficient with a broadband absorption spanning from ultraviolet to green region of the visible spectrum, along with a long‐lived triplet state generated via efficient intersystem crossing (ISC). Utilizing the triplet‐triplet energy transfer (TTEnT) strategy, CBI catalyzes diverse reactions under green light irradiation. Through this, we propose CBIs as a new class of heavy‐atom‐free visible‐light sensitizers overcoming the limitations of conventional sensitizers, such as low extinction coefficient in the visible regime, short triplet‐state lifetimes, and high toxicity, by relying on heavy atoms.