Tuning the Photophysical and Redox Properties of Metallocorroles by Iodination

Facile procedures
were developed for selective iodination of aluminum
and gallium corroles; crystallographic characterization shows that
the main structural aspects are not changed (the macrocycle remains
planar). Absorption maxima are red-shifted by 3–5 nm/iodine,
singlet lifetimes are reduced to <80 ps, and emissions from long-lived
excited states come into effect. The iodinated corroles display prompt
fluorescence, phosphorescence, and delayed thermal fluorescence, all
at room temperature. The effect on redox potentials appears to be
additive for each additional iodine and, surprisingly, is practically
identical to that of the other three halides. The conclusions of this
work are of large importance for the design of metallocorroles that
are best suited for the various applications where metallocorroles
are used as catalysts and photosensitizers.