A focus on lucigenin as a potent photoredox catalyst

Old dog, new tricks: The well-established fluorescent and chemiluminescent probe lucigenin (Luc²⁺, N,N'-dimethyl-9,9'-bisacridinium), can also act as a powerful photoredox catalyst. Readily commercially available as a nitrate salt, a straightforward anion exchange to the more lipophilic Luc²⁺(BF₄ ^-)₂ was recently demonstrated by Feringa and coworkers to afford a soluble, versatile catalyst (A. Matei, B. Roure, X. Chen, S. B. Beil and B. L. Feringa, Chem. Sci., 2026, 17, 11436, https://doi.org/10.1039/d6sc02111e). Due to its high excited-state reduction potential, this dicationic scaffold enabled the oxidative azolation of unactivated arenes with a broad substrate scope.