Flattened Calixarene-like Cyclic BODIPY Array: A New Photosynthetic Antenna Model

A cyclic
BODIPY array, characterized by a rigid flattened calixarene-like
conformation, acts as a photosynthetic antenna mimic. The system in
question, triBODIPY, is a better antenna than the corresponding
BF2-free ligand. On the basis of absorption spectral studies
and supporting calculations, it is concluded that exciton coupling
between the BODIPY subunits occurs readily. TriBODIPY supports a complex with Li+@C60 that bring an antenna-like
light absorber into close proximity to an electronic acceptor without
the need for linking spacers. As inferred from X-ray diffraction analyses
of complexes between triBODIPY and C60, it is inferred that the fullerene complexes
are stabilized via convex–concave donor–acceptor interactions.
Steady state absorption/fluorescence, time-correlated single photon
counting, and transient absorption measurements have allowed a complete
characterization of the complexes in both the ground and excited states,
including the host–guest recognition features, fluorescence
quenching effects, and charge separation/recombination dynamics.