BODIPY Dye for Light-initiated Ni-catalyzed C-N Cross-Coupling Reaction

Over the past years, Traditional Buchwald-Hartwig amination relies on costly Pd catalysts and high temperature, limiting sustainability and scalability. To overcome this drawback, photoactivated C-N cross-coupling reactions, which incorporate photocatalysts (PC) and a less expensive nickel system, have emerged as a promising alternative. Currently, organic photocatalysts are favored for sustainable processes, but the use of either high-energy UV light or blue light as a light source raises concerns due to potential substrate degradation and biological safety risk. To address these challenges, this work reports the development of the first white-light-activated BODIPY-functionalized ligand (4-Py-BDP) for Ni-catalyzed C–N cross-coupling reactions. This system achieves efficient C–N bond formation at room temperature, yielding up to 84%. The Photophysical characterization of 4-Py-BDP revealed strong absorption at 504 nm (ε = 98,084 M⁻¹ cm⁻¹), emission at 518 nm, and a fluorescence lifetime of 1.88 ns in DCM. The photocatalyst enabled effective coupling between electron-deficient aryl iodides and secondary amines with good to excellent yields. The preliminary studies with mass spectroscopy, UV-VIS, fluorescence spectroscopy, and 1H NMR showed that the formation of a Ni–amine complex appears to be a key intermediate for the amine and iodobenzene derivatives coupling reaction. The reaction mechanism proceeds via the in-situ generation of [Ni(4-Py-BDP)(amine)3Br2] complex to photoinduced reduction of [Ni(4-Py-BDP)(amine)3Br2] to Ni(I) via Förster resonance energy transfer (FRET). This Ni(I) consequently proceeds the reaction through Ni(I) – Ni(0) – Ni(II) cycle.