Bodipy - Corrole dyad with truxene bridge: Photophysical Properties and Application in Triplet - Triplet Annihilation upconversion

Free base corrole can generate triplet state without relying on the heavy-atom effect, however, its absorption in the visible spectral range (430-650 nm) is very weak which makes corrole not an ideal triplet photosensitizer. Herein, we prepared a novel truxene-bridged Bodipy - corrole dyad (B -T - Co) which have strong, broad absorption in Uv-visible spectral range (300 nm - 676 nm, the maximum molar absorption coefficient is up to 1.09 - 10(5) M-1 cm(-1) at 426 nm). The dyad showed fast singlet-singlet energy transfer from Bodipy moiety to corrole moiety (2.16 - 10(8)s(-1)), high strong singlet-oxygen (O-1(2)) photosensitizing ability (70%), prolonged triplet state lifetimes (149 mu s) and high triplet state energy levels (1.41 eV) as compared to corrole (singlet-oxygen photosensitizing ability: 58%; triplet lifetimes: 116 mu s; triplet energy levels: 1.32 eV). Moreover, the dyad used as triplet photosensitizer for triplet-triplet annihilation upconversion, with red excitation at 589 nm, the upconversion emission intensity is higher than the corrole itselef and the upconversion quantum yield (2.57%) increases by ca. 2-folds.