Corrole-BODIPY Dyads: Synthesis, Structure, and Electrochemical and Photophysical Properties

A free-base and its Cu­(III) derivative
of bichromophoric meso-β linked corrole-BODIPY
dyad were synthesized and structurally characterized by single crystal
X-ray diffraction (XRD). Both corrole and BODIPY fragments maintained
respective ground state electronic isolation despite their connection
through a single bond due to a tilted orientation as observed by XRD.
This was further supported by UV–vis and cyclic voltammetric
studies. The Cu­(III)-metalated dyad exhibits temperature-dependent
paramagnetic behavior as observed in the variable temperature 1H NMR due to the presence of a Cu­(II)-corrole-π-cation
radical. Importantly, the free-base exhibits complete fluorescence
quenching probably due to photoinduced electron transfer to a low
lying charge separated state. Interestingly, emission was regained
upon addition of 1,8-diazabicyclo[5.4.0]­undec-7-ene (DBU) due to
the deprotonation
of corrole. The “turn on” fluorescence behavior and
the presence of acidic NH protons were further exploited toward basic
anion sensing utility.