CC BY-NC 3.0 UnportedLi, ChenfeiDickson, RobertRockstroh, NilsRabeah, JaborCordes, David B.Slawin, Alexandra M.Z.Hünemörder, PaulSpannenberg, AnkeBühl, MichaelMejía, EstebanZysman-Colman, EliKamer, Paul C.J.2021-09-032021-09-032020https://oa.tib.eu/renate/handle/123456789/6692https://doi.org/10.34657/5739A family of six structurally related heteroleptic copper(i) complexes of the form of [Cu(N^N)(P^P)]+ bearing a 2,9-dimethyl-1,10-phenanthroline diimine (N^N) ligand and a series of electronically tunable xantphos (P^P) ligands have been synthesized and their optoelectronic properties characterized. The reactivity of these complexes in the copper-photocatalyzed aza-Henry reaction of N-phenyltetrahydroisoquinoline was evaluated, while the related excited state kinetics were comprehensively studied. By subtlety changing the electron-donating properties of the P^P ligands with negligible structural differences, we could tailor the photoredox properties and relate them to the reactivity. Moreover, depending on the exited-state redox potential of the catalysts, the preferred mechanism can shift between reductive quenching, energy transfer and oxidative quenching pathways. A combined study of the structural modulation of copper(i) photocatalysts, optoelectronic properties and photocatalytic reactivity resulted in a clearer understanding of both the rational design of the photocatalyst and the complexity of competing photoinduced electron and energy transfer mechanisms. © The Royal Society of Chemistry.enghttps://creativecommons.org/licenses/by-nc/3.0/540Energy transferExcited statesLigandsPhotocatalytic activityQuenchingReaction kineticsReaction productsRedox reactionsSynthesis (chemical)Electron donating propertiesElectronically tunableEnergy transfer mechanismsExcited state kineticsOptoelectronic propertiesPhotocatalytic reactivityStructural differencesStructural modulationsCopper compoundsArticle