Status report on copper (I) complexes in photoredox catalysis; photophysical and electrochemical properties and future prospects

Abstract

Visible-light photoredox catalysis has become a practical tool in the last years for driving energy-demanding chemical reactions. Owing to their exceptional photoelectrochemical properties, classical octahedral ruthenium and iridium complexes still dominate the field of photoredox catalysis despite their drawbacks, such as sustainability and costs. Luminescent Cu (I) complexes are considered one of the most plausible candidates to replace such traditional Ru- and Ir photoredox catalysts in the near future. This review covers the development of Cu(I) complexes for photoredox catalysis with a special focus on collecting and categorizing the available photophysical and electrochemical information. The principal characteristics, advantages, drawbacks and examples of applications of the distinct classes (homoleptic, heteroleptic, in-situ generated tetra/tri/di coordinated, etc.) of Cu(I) complexes used as photoredox catalysts are presented and discussed in a systematic manner. The strategies that have been implemented to extend the lifetimes and to control the photo/electrochemical properties of Cu(I) complexes are detailed with particular emphasis on the role and potential of using dative carbon contact atoms in different ligand scaffolds. Especially, the incorporation of carbon-donor ligands such as isonitriles and carbenes has been proven to be a promising approach for controlling the photoelectrochemical properties and stability of photoredox catalysts.