Hydrogen‐Bonded Organic Frameworks Supported Au(I)/Au(0) Mixed‐Valence Nanoparticles for Visible‐Light‐Driven Selective Oxidation of Sulfides

ABSTRACT

Selective oxidation of sulfides to sulfoxides is often plagued by overoxidation to sulfones and catalyst deactivation. Herein, we report a heterogeneous catalyst comprising Au(I)/Au(0) mixed‐valence nanoparticles supported on hydrogen‐bonded organic framework HOF‐101 (AuNP@HOF‐101). Using HAuCl ₄ as the gold precursor, the π‐conjugated framework of HOF‐101 stabilizes Au(I) species, and controlled stepwise reduction with NaBH ₄ spontaneously generates well‐dispersed AuNPs (mean diameter 1.8 nm) with a stable Au(0)/Au(I) ratio of 72:28. The π···Au interactions stabilize the mixed‐valence state against disproportionation. Under visible‐light irradiation, HOF‐101 generates singlet oxygen ( ¹ O ₂ ), while surface Au(I) sites anchor sulfides through soft acid‐soft base interactions. Using methyl phenyl sulfide as a model substrate, AuNP@HOF‐101 achieves 93.8% conversion with 98.2% sulfoxide selectivity under mild conditions (room temperature, O ₂ atmosphere). The catalyst demonstrates broad substrate compatibility and excellent recyclability over ten cycles without significant activity loss or gold leaching (<0.3%). This work establishes a new paradigm for designing stable mixed‐valence gold nanoparticle catalysts within HOFs for selective oxidation reactions.