Development of the Peripheral Functionalization Chemistry of meso-Free Corroles

In contrast to the extensive development of the meso-functionalization of porphyrins, that of corroles had rarely been explored until the development of practical synthetic methods for meso-free corroles in 2015. The ready availability of meso-free corroles opened up meso-functionalization chemistry of corroles, giving rise to successful synthesis of various meso-substituted corroles such as meso-halogen, meso-nitro, meso-amino, meso-oxo, and meso-iminocorroles as well as meso–meso-linked corrole dimers and corrole tapes. In some cases, 2NH corroles exist as stable or transient radical species. The impact of meso-functionalization on the structures, electronic properties, optical characteristics, and aromaticity of corroles are highlighted in this Minireview.