Nitrogen heterocycles serve as key structural components in modern pharmaceutical, materials, and agrochemical applications. Addressing the intrinsic limitations of conventional C-N coupling catalysts—particularly their poor catalytic efficiency and narrow substrate range—this investigation engineered an advanced catalytic architecture based on an Al(BPY) metal-organic framework (MOF). The synthetic route involved: (1) hydrothermal assembly of microporous Al(BPY) MOF employing 2,2'-bipyridine (BPY, rigid bidentate N-ligand) and AlCl₃, followed by (2) controlled liquid-phase loading of Cu(BF₄)₂ as a bifunctional reagent (dual etchant and metal source). This innovative approach successfully accomplished two critical objectives concurrently: (i) in situ formation of hierarchically porous networks (pore size distribution: 1-50 nm) and (ii) atomic-level precision immobilization of mono-disperse copper active centers. Structural analysis showed BF₄⁻ etches Al-O-C bonds forming mesopores, while Cu²⁺ coordinates with pyridinic N ensuring atomic dispersion. Rigorous evaluation of Al(BPY)-Cu(BF₄)₂'s catalytic behavior in Ullmann C-N coupling reactions established distinct structure-activity correlations, with the Cu(BF₄)₂-modified catalyst exhibiting substantially superior activity relative to Cu(NO₃)₂-, CuCl₂-, and Cu(acac)₂-modified analogs. The Al(BPY)-Cu(BF₄)₂-0.5 demonstrated optimal catalytic performance, achieving 93% product yield under optimized reaction parameters (Cs₂CO₃ base, DMSO solvent, 120°C, 16 h). Notably, the catalyst displayed exceptional functional group compatibility (55%-95% yields across 42 diverse substrates including fused-ring systems, non-aromatic N-heterocycles, and P-H compounds) while maintaining remarkable tolerance toward both electronic and steric perturbations. The system successfully transcended conventional catalytic constraints by accomplishing: (i) efficient coupling of sterically demanding non-aromatic amines and (ii) pioneering MOF-mediated C-P bond formation—the first documented instance of such transformation in MOF-based catalytic systems. Furthermore, the material exhibited outstanding cycling stability, retaining >94% initial activity through 8 successive reaction cycles with negligible copper leaching (<0.2 ppm). The exceptional catalytic efficiency originates from synergistic interplay between hierarchically porous channels (facilitating enhanced mass transport and active site accessibility) and atomic Cu centers (activating aryl iodides and X-H bonds).

Key words: Hierarchically porous MOF, Single-atom copper sites, Nitrogen heterocycles, C-N coupling