Metallocorrole complexes of third row transition metals (see Formula I below) may be used as therapeutic agents, catalysts, components of oxygen detectors, and components of light emitting diodes. In particular, metallocorrole complexes of third row transition metals may be used as improved photosenitizers in photodynamic therapy; as improved catalysts in aziridination, epoxidation, and water splitting reactions; as improved in vivo imaging agents; and as improved components in the emissive layer of OLEDs. Due to their strongly sigma-donating nature, corroles are able to stabilize third row transition metals in high oxidation states. Third row transition metals are significantly more electropositive than their first and second row counterparts and may therefore act as improved catalysts. In addition, the high spin-orbit coupling constants of third row transition metals may lead to easier singlet-triplet inter-system crossing in the excited state, which in turn may allow for long-wavelength phosphorescence that is desirable for many applications.