Xu‐Shuang Han

Great efforts have been made to establish the structure-property relationships of ligand-protected metal nanoclusters. An alkynyl-protected gold nanocluster Au₂₈(^tBuC₆H₄C≡C)₂₀ (Au₂₈-C₂) was synthesized and structurally characterized. It has an isostructural metal kernel and a quite similar ligand shell to its counterpart Au₂₈(^tBuC₆H₄S)₂₀ (Au₂₈-S), which provides a valuable platform for studying ligand effects on the luminescence of clusters. The emission intensity of Au₂₈-C₂ in solution is ∼10-fold that of Au₂₈-S. The only structural difference between these two clusters is the donor atom or group, i.e., C≡C for Au₂₈-C₂ versus S for Au₂₈-S. Temperature-dependent experiments indicate that the two Au₂₈ clusters have different thermodynamic behaviors and radiative processes. The study on the excited-state dynamics by transient absorption spectroscopy indicates that Au₂₈-C₂ has a larger triplet-state population than Au₂₈-S. This work shows important ligand effects on the emission properties of metal nanoclusters, which provide new perspectives for the designed synthesis of functional metal nanoclusters.

The first all‐amidinate‐protected gold nanocluster [Au₂₈(Ph−form)₁₂](OTf)₂ (Ph‐form=N,N′‐diphenylformamidinate) (Au₂₈) has been synthesized and structurally resolved. Single crystal X‐ray diffraction reveals that Au₂₈ has a compact Au₄@Au₂₄ tetrahedral core–shell structure of T symmetry, which is fully protected by 12 bridging formamidinate ligands. This cluster is quite robust as indicated by the fact that it can stay intact in solution at 80 °C for 6 d. It exhibits excellent catalytic performance for the electroreduction of CO₂ with 96.5 % Faradaic efficiency (FE) at −0.57 V and a maximum TOF of 1731 h⁻¹ at −0.87 V. Its superior stability is also manifested in the fact that the supported catalyst Au₂₈/CNTs maintains stable potentials at ca. −0.69 V for 40 h with FE(CO)s>91 %. A superatomic electron configuration of 1S²1P⁶2S²1D⁴ has been clarified by DFT computations, and the strong gold–ligand binding and geometric shell closure account for the superior stability of Au₂₈.

The first all‐amidinate‐protected gold nanocluster [Au₂₈(Ph−form)₁₂](OTf)₂ (Ph‐form=N,N′‐diphenylformamidinate) (Au₂₈) has been synthesized and structurally resolved. Single crystal X‐ray diffraction reveals that Au₂₈ has a compact Au₄@Au₂₄ tetrahedral core–shell structure of T symmetry, which is fully protected by 12 bridging formamidinate ligands. This cluster is quite robust as indicated by the fact that it can stay intact in solution at 80 °C for 6 d. It exhibits excellent catalytic performance for the electroreduction of CO₂ with 96.5 % Faradaic efficiency (FE) at −0.57 V and a maximum TOF of 1731 h⁻¹ at −0.87 V. Its superior stability is also manifested in the fact that the supported catalyst Au₂₈/CNTs maintains stable potentials at ca. −0.69 V for 40 h with FE(CO)s>91 %. A superatomic electron configuration of 1S²1P⁶2S²1D⁴ has been clarified by DFT computations, and the strong gold–ligand binding and geometric shell closure account for the superior stability of Au₂₈.