Red-emitting fluorogenic BODIPY-tetrazine probes for biological imaging.

A series of new BODIPY-tetrazine derivatives have been developed with a twist intramolecular charge transfer (TICT) state in polar solvents, which is an electron transfer process that occurs upon photoexcitation in a molecule that usually consists of an electron donor and acceptor linked by a single bond. Among them, the BODIPY-tetrazine derivative 6i was stable towards long-term storage and red-emitting with excellent performance, and was further used to image trans-cyclooctene-labeled lipids in mammalian cells and cyclopropene-labeled sugars in cancer cells under no-wash conditions.