A metal-DNA biohybrid as enantioselective artificial photoDNAzyme

Visible light photocatalysis, which exploits the reactivity of molecules at their excited state, has triggered a paradigm shift in organic synthesis by enabling some very unique chemical transformations. Yet, achieving precise control of the enantioselectivity in such processes remains a major challenge. A promising strategy involves linking a synthetic transition metal photocatalyst within the chiral architecture of a biomolecule to create a highly selective artificial metallo-photoenzyme. However, such an artificial metalloenzyme that integrates the merits of biocatalysis and photocatalysis to promote abiological reactions with high enantioselectivity is still unknown. Here, we report an artificial metallo-photoDNAzyme resulting from the covalent anchoring of a visible light-absorbing iridium-based photocatalyst within a double-stranded (ds)DNA helix, exhibiting efficient triplet-triplet energy transfer and high levels of enantioselectivity in [2 + 2] intramolecular cycloadditions.