Lanthanide Luminescence in Visible-Light-Promoted Photochemical Reactions

The excitation of lanthanides with visible light to promote photochemical reactions has garnered interest in recent years. Lanthanides serve as initiators for photochemical reactions because they exhibit visible-light-promoted 4f→5d transitions that lead to emissive states with electrochemical potentials that are more negative than the corresponding ground states. The lanthanides that have shown the most promising characteristics for visible-light promoted photoredox are Sm^II, Eu^II, and Ce^III. By understanding the effects that ligands have on the 5d orbitals of Sm^II, Eu^II, and Ce^III, luminescence and reactivity can be rationally modulated using coordination chemistry. This review briefly overviews the photochemical reactivity of Sm^II, Eu^II, and Ce^III with visible light; the properties that influence the reactivity of these ions; and the research that has been reported towards modulating their photochemical-relevant properties using visible light and coordination chemistry.