Digold photosensitizer for visible light [2 + 2] cycloaddition and E/Z isomerization reactions.

Energy transfer photocatalysis has emerged as a powerful platform for a wide variety of transformations, yet advances in this area are often limited by the visible-light absorption of catalysts and the very high cost of state-of-the-art iridium-based sensitizers. We report the synthesis, characterization, and photocatalytic use of a novel digold(I) complex, {[Au(IPr)]₂(DHIC)} (PhotAu3), designed to overcome these limitations by absorbing visible light in the blue region and proving catalytically effective under 450 nm LED irradiation. The complex was successfully applied to a range of EnT-mediated photocatalytic reactions, including intramolecular [2 + 2] cycloadditions and E/Z isomerizations, achieving high conversions at low catalyst loadings in short reaction times.