New Photosensitizers Based on Heteroleptic CuI Complexes and CO2 Photocatalytic Reduction with [NiII(cyclam)]Cl2

Earth-abundant metal complexes have been at-tracting increasing attention in the field of photo(redox)ca-talysis. In this work, the synthesis and full characterisation offour new heteroleptic CuI complexes are reported, whichcan work as photosensitizers. The complexes bear a bulkydiphosphine (DPEPhos = bis[(2-diphenylphosphino)phenyl]ether) and a diimine chelating ligand based on 1-benzyl-4-(quinol-2’yl)-1,2,3-triazole. Their absorption has a relativemaximum in the visible-light region, up to 450 nm. Thus,their use in photocatalytic systems for the reduction of CO2with blue light in combination with the known catalyst[NiII(cyclam)]Cl2 was tested. This system produced CO as themain product through visible light (l = 420 nm) with a TONup to 8 after 4 hours. This value is in line with other photo-catalytic systems using the same catalyst. Nevertheless, thissystem is entirely noble-metal free.