Theoretical study on a novel Au99+31n(SR)40+10n cluster sequence with D5 symmetry†

The cluster sequences with analogous structures are of significant importance for elucidating the evolutionary patterns in both structural configurations and electronic architectures of RS-AuNCs. Despite substantial efforts devoted to synthesizing and characterizing a series of single-crystal structures of RS-AuNCs, the scarcity of well-defined single-crystal structures for large-sized cluster sequences has impeded comprehensive understanding of structure–property correlations within this size regime. This work presents a theoretical investigation of a novel series of Au_99+31n(SR)_40+10n (where n = 0, 1, 2, 3) clusters exhibiting D₅ symmetry. The structural evolution of the cluster sequence emerges as a one-dimensional linear extension of the Au₉₉(SR)₄₀ (n = 0) kernel framework, demonstrating a quantized growth pattern where each successive expansion event is accompanied by a precise 21 valence electron increment. The DFT calculations reveal that this series of clusters exhibit significantly negative average formation energies (E_ave), confirming their exceptional thermodynamic stability. The sTDA calculations demonstrate that Au₁₆₁(SR)₆₀ and Au₁₉₂(SR)₇₀ clusters display characteristic surface plasmon resonance (SPR) peak in their UV-Vis, indicating a size-induced transition from molecular to metallic states in these clusters. Furthermore, the aspect ratio is proposed as a potential critical geometric parameter governing the emergence of metallic characteristics in the Au₁₉₂(SR)₇₀ cluster.