Hierarchical Architecture of Anisotropic Alkynyl-Protected Au₂₂ Nanoclusters Enables Accelerated Photo-/Thermo-Dual...

Hierarchical architectures of anionic ligand-protected gold nanoclusters (AuNCs) represent multiple catalytic properties originating from the structural components, including the superatomic core and surrounding staple motifs in conventional spherical AuNCs. We herein report the first finding of identical triple functions arising from the structural components of alkynyl-protected anisotropic Au₂₂ nanoclusters (NCs), namely, the superatomic molecular core as well as the surrounding ring and staple moieties. These cooperative functions enable accelerated photo-/thermo-dual catalysis for cross-dehydrogenative coupling reactions between terminal alkynes and aliphatic tertiary amines. The superior photosensitization ability of anisotropic Au₂₂ NCs bearing a superatomic [Au₇]³⁺ core, compared with spherical Au₂₅ NCs containing a [Au₁₃]⁵⁺ core, was confirmed by a probe reaction for photosensitized singlet oxygen generation. Ligand-exchange experiments clarified smooth alkynyl ligand exchange at the staple motifs, while the ring sites remained intact. Association experiments further indicated that intermolecular hydrogen bonding between the ligands and amine substrate plays a crucial role in the observed reaction acceleration. Density functional theory calculations supported both the energetically favorable reaction pathway and the efficient photosensitization behavior, which arises from reversible singlet-triplet excited states. This work highlights the tunability of multiple catalytic properties in anisotropic metallic nanoclusters through rational design of catalytic functions embedded in their hierarchical architectures, thereby promoting further catalytic engineering of metallic nanoclusters toward sustainable organic synthesis.