Confining Cu(I) Ions within an Ir(III)-Based Twin-Cavity Cage for Photo-Triggered Dioxygen Activation toward C(sp³)−H Oxidation.

Abstract

Efficient dioxygen (O2) activation under mild and environmentally friendly conditions remains a challenging yet crucial research area in chemistry. In this study, by rationally modulating the coordination environment of Cu(I) ions and integrating a photoactive Ir(III) module into a supramolecular system, we introduce a simple yet effective approach for O2 activation (O2→1O2→O2•-) under LED irradiation (450 nm), leading to efficient C(sp3)−H photo-oxidation of N-aryl tetrahydroisoquinolines. The hexaformyl end-capped fac-Ir(ppy)₃ module (1), Ir(III)-based twin-cavity cage (2), and the supramolecular Cu2@2 entity—where two Cu(I) ions are coordinated within cage 2—were comprehensively characterized using NMR, HR-MS, and X-ray crystallography. The confined cavities of 2 effectively trap Cu(I) ions, shielding them from oxidation by O₂. However, mechanistic studies reveal that the photoinduced singlet oxygen (¹O₂) generated from the fac-Ir(ppy)₃ module could activate Cu(I), facilitating the generate superoxide radical (O2•-) species. Importantly, the regeneration of the Cu(I) active redox state can be accomplished through electron transfer from the photoactive *Ir(III) to the resulting Cu(II) ions. This study introduces a gradual and controlled energy/electron delivery process from Ir(III) module to O2 and the Cu centres, offering an advanced supramolecular strategy for visible light-induced O2 activation in oxidation reactions.