Photoredox catalysis has become an extremely valuable process in organic synthesis. The most popular photocatalysts are based on ruthenium(II) and iridium(III) complexes such as [Ru(bpy)3]2+ and fac-Ir(ppy)3. The detracting feature of these catalysts is that the metals are both expensive and toxic.[1,2] Copper(I) complexes present an inexpensive and versatile alternative for use in photoredox catalysis, which has enticing potential for small molecule transformations.[2]

We present the design, computational modelling, synthesis and optoelectronic characterisation of a series of photoactive Cu(I)-NHC complexes,[3] which are designed to negatively shift the excited state oxidation potential and so be better photoreductants. We also show preliminary efforts of their use in a range of photocatalytic organic transformations including C-H activation, C-C bond forming, ATRA and energy transfer reactions.[4,5]

[1]: B. M. Hockin, C. Li, N. Robertson and E. Zysman-Colman, Catal. Sci. Technol., 2019, 9, 889, 10.1039/C8CY02336K.
[2]: C. K. Prier, D. A. Rankic, and D. W. C. MacMillan, Chem. Rev., 2013, 113, 5322, 10.1021/cr300503r.
[3]: R. Marion, F. Sguerra, F. Di Meo, E. Sauvageot, J.-F. Lohier, R. Daniellou, J.-L. Renaud, M. Linares, M. Hamel, and S. Gaillard, Inorg. Chem., 2014, 53, 9181, 10.1021/ic501230m.
[4]: S. Parisien-Collette, A. C. Hernandez-Perez, and S.K. Collins, Org. Lett., 2016, 18, 4994, 10.1021/acs.orglett.6b02456.
[5]: M. Pirtsch, S. Paria, T. Matsuno, H. Isobe, and O. Reiser, Chem. Eur. J., 2012, 18, 7336, 10.1002/chem.201200967.