Heterogeneous Bifunctional Ni Single-Atom Catalyst on Carbon Nitride for Selective C(sp²)–C(sp³) Coupling

The efficient formation of C(sp2)-C(sp3) bond is essential, particularly in pharmaceutical synthesis, where the incorporation of sp3-rich motifs is highly desirable. Despite the growing demand for sustainable synthetic methods, heterogeneous C(sp2)-C(sp3) coupling remains underexplored. In this work, we present a ligand-tuned heterogeneous bifunctional catalytic system that employs nickel single atoms supported on carbon nitride (Ni1/CN) for visible-light-driven C(sp2)-C(sp3) coupling reactions. We experimentally and computationally demonstrate that the coordination of bidentate bipyridine ligands to Ni single atoms anchored on carbon nitride enables the efficient transformation of alkyl boronic esters into C(sp2)-C(sp3) coupled products with high activity and selectivity. Furthermore, beyond C(sp2)-C(sp3) coupling, the system exhibits remarkable versatility. Modulating ligand environments allows for distinct transformations: replacing the bidentate ligand with monodentate ligands facilitates C-X coupling (X = O, N), while ligand-free conditions enable selective aerobic oxidation. This tunable catalytic platform streamlines pharmaceutical synthesis and underscores the potential of single-atom catalysts in green chemistry and complex organic transformations.