The stability of a photocatalyst under irradiation is
important
in photoredox applications. In this work, we investigated the stability
of a thermally activated delayed fluorescence (TADF) photocatalyst
{3DPAFIPN [2,4,6-tris(diphenylamino)-5-fluoroisophthalonitrile]},
recently employed in photoredox-mediated processes, discovering that
in the absence of quenchers the chromophore is unstable and is efficiently
converted by irradiation with visible light into another species based
on the carbazole-1,3-dicarbonitrile moiety. The new species obtained
is itself a TADF emitter and finds useful applications in photoredox
transformations. At the excited state, it is a strong reductant and
was efficiently applied to cobalt-mediated allylation of aldehydes,
whereas other TADFs (4CzIPN and 3DPAFIPN) failed to promote efficient
photocatalytic cycles.