Remote Control by π‑Conjugation of the Emissive Properties of Fischer Carbene-BODIPY Dyads

The
synthesis, structure, and complete characterization of mono- and bimetallic
dyads joining Fischer carbene complexes and BODIPY chromophores are
reported. In these organometallic species, the Fischer carbene complex
is attached to the BODIPY moiety through a p-aminophenyl
group linked at the C8 carbon atom of the BODIPY core. The photophysical
properties, namely the corresponding UV/vis absorption and emission
spectra of these new metal–carbene complexes, are analyzed
and discussed. It is found that whereas the absorption of the considered
dyads strongly resembles that of the parent 4-anilinyl-substituted
BODIPY, the fluorescence emission is significantly reduced in these
species, very likely as a result of a Förster-type energy transfer
mechanism. At variance, the replacement of the pentacarbonyl-metal(0)
fragment by a carbonyl group leads to high fluorescence emission intensity.
In addition, the emissive properties of the BODIPY core in these organometallic
dyads can be tuned by remote groups by means of π-conjugation,
as supported by density functional theory calculations.