Functions of bioinspired pyrrole cobalt complexes–recently developed catalytic systems of vitamin B₁₂ related complexes and porphycene complexes–

Pyrrole-containing metal complexes widely exist in nature, for example, vitamin B₁₂, heme, chlorophyll, and their derivatives. Each of them shows significant functions, which are essential for life. To mimic their important functions and substance conversion reactions, numerous pyrrole-containing metal complexes have been synthesized and investigated. This review mainly focuses on cobalt complexes having pyrrole-containing ligands and the recent progress of molecular transformations catalyzed by the complexes, especially the vitamin B₁₂-related cobalt complexes and porphycene cobalt complexes. A variety of reaction systems, which enable a number of molecular transformations under mild conditions is described. The construction of new reaction systems and a combination of the materials inspired by natural systems is a promising and effective approach to realizing eco-friendly and cost-effective reaction systems.