Singlet Fission in Carbene Derived Diradicaloids

In large, the documentation of singlet fission (SF) is showcased in examples involving polyacenes and polyenes. SF has been hitherto studied in depth, on one hand, in solids and, on the other hand, in solutions, in which cases covalent bridges are required to link two or more chromophores. Going beyond polyacenes and polyenes is driven by exploring new classes of SF-materials. Herein, we present a new class of SF-materials based on diradicaloids of carbene scaffolds, namely cyclic (alkyl)(amino)carbenes (CAACs). Our modular approach allows for tuning two key SF-criteria: the steric factor and the diradical character. In turn, we modified the energy landscapes of excited states in a systematic manner to accommodate the needs for SF. We report the first example on intermolecular SF in solutions for CAAC dimers formed via self-assembly at cryogenic temperatures.