Iron Photoredox Catalysis-Past, Present, and Future

Photoredox catalysis of organic reactions driven by iron has attracted substantial attention throughout recent years, due to potential environmental and economic benefits. In this Perspective, three major strategies were identified that have been employed to date to achieve reactivities comparable to the successful noble metal photoredox catalysis: (1) Direct replacement of a noble metal center by iron in archetypal polypyridyl complexes, resulting in a metal-centered photofunctional state. (2) In situ generation of photoactive complexes by substrate coordination where the reactions are driven via intramolecular electron transfer involving charge-transfer states, for example, through visible-light-induced homolysis. (3) Improving the excited-state lifetimes and redox potentials of the charge-transfer states of iron complexes through new ligand design. We seek to give an overview and evaluation of recent developments in this rapidly growing field and, at the same time, provide an outlook on the future of iron-based photoredox catalysis.

Automated summary

Photoredox catalysis driven by iron has gained significant attention in recent years due to its potential environmental and economic benefits. This Perspective highlights three major strategies that have been used to achieve reactivities comparable to noble metal photoredox catalysis. The strategies include replacing noble metal centers with iron, generating photoactive complexes through substrate coordination, and improving the properties of charge-transfer states through ligand design. This article provides an overview and assessment of recent developments in this rapidly growing field and discusses the future prospects of iron-based photoredox catalysis.