A Metal-DNA biohybrid as Enantioselective Artificial PhotoDNAzyme

Visible light photocatalysis that exploits the reactivity of molecules at their excited state has induced a paradigm shift in organic synthesis by enabling unique chemical transformations, but controlling their enantioselectivity has proven difficult. A promising strategy involves linking a synthetic transition metal photocatalyst within the chiral architecture of a biomolecule to create a highly selective artificial photoenzyme. However, such a biohybrid system that combines the merits of biocatalysis and metallo-photocatalysis to promote abiological reactions fueled by visible light with high enantioselectivity is still unknown. Here, we report on an artificial metallo-photoDNAzyme resulting from covalently anchoring a blue light absorbing iridium-based photocatalyst within a double-stranded DNA helix that exhibits efficient triplet-triplet energy transfer and high levels of enantioselectivity in [2+2] intramolecular cycloadditions.