Modulation of the Cu Coordination Microenvironment in Metal–Organic Frameworks for C(sp ² )–N Coupling Reactions

The precise modulation of the microenvironment of metal sites in metal–organic frameworks (MOFs) has become a research hotspot, but the conformational relationship between the coordination environment and catalytic activity still lacks an atomic-level mechanism. Herein, efficient C(sp2)–N coupling between phenothiazines and unprotected phenols was achieved under mild conditions by modulating the Cu coordination environment of Cu-UiO-66-X (X = −NO2, −H, −OH). Notably, Cu-UiO-66-X catalysts with specific −X group coordination microenvironments exhibit significant activity differences in the C(sp2)–N coupling reaction (activity order: −NO2 > −H > −OH). The introduction of specific −X groups through MOF organic linkers can precisely regulate the coordination environment of the Cu site and thus its electronic properties. The experimental and characterization results show that the specific −X group can precisely regulate the electronic properties at the Cu site, thus significantly enhancing the catalytic activity.