Isoreticular Azobenzene Functionalization of Ultrastable Lead Chloride Hybrids for Enhanced Photocatalytic Aerobic Oxidation

Lead halide hybrids have emerged as highly efficient photocatalysts, yet their application in photocatalytic organic synthesis remains limited, largely due to their instability upon polar organics. Herein, we have developed an isoreticular synthetic strategy to functionalize lead chloride-based MOFs with azonbenzene units, a benchmark photoresponsive moiety. The three MOFs consist of isostructural 1D [PbCl]+ chains as SBUs and biphenyl/azobenzene dicarboxylates as struts. Compared with the parent biphenyl-MOF, the azobenzene-functionalized MOFs demonstrate broad wavelength coverage up to 620 nm. Their efficient photoinduced ligand-to-metal charge transfer affords enhanced electron–hole separation for long-lived free carriers. Among them, the 4,4′-azobenzene-functionalized MOF exhibits the most efficient photocatalytic aerobic oxidation in both C(sp3)-H photooxidation and benzylamine coupling. Meanwhile, these coordination assembled MOFs exhibit high stability in a wide pH range and polar organic compounds. This work showcases a rational strategy to modify lead halide hybrids at the molecular level while preserving the lattice topology.