Poly(Heptazine Imide) Ligand Exchange Enables Remarkable Low Catalyst Loadings in Heterogeneous Metallaphotocatalysis

The development of heterogeneous metallaphotocatalysis is of great interest for sustainable organic synthesis. The rational design and controllable preparation of well-defined (site-isolated) metal/photo bifunctional solid catalysts to meet such goals remain a critical challenge. Herein, we demonstrate the incorporation of privileged homogeneous bipyridyl-based Ni-catalysts into highly ordered and crystalline potassium poly(heptazine imide) (K-PHI). A variety of PHI-supported cationic bipyridyl-based Ni catalysts (LnNi-PHI) have been prepared and fully characterized by various techniques, including NMR, ICP-OES, XPS, HAADF-STEM, and XAS. The LnNi-PHI catalysts exhibit exceptional chemical stability and recyclability in diverse C−P, C−S, C−O, and C−N cross-coupling reactions. The proximity and cooperativity effects in LnNi-PHI significantly enhance the photo/Ni dual catalytic activity, thus resulting in low catalyst loadings and high turnover numbers.