Core packing-dependent metallic transition in thiolate-protected gold nanoclusters: twinned-FCC vs. pure-FCC configurations

Abstract

Herein, we computationally predict two FCC gold nanoclusters, Au₂₁₂(SR)₆₀ and Au₂₂₄(SR)₇₂, featuring octahedral Au₆ cores at the 200-atom scale. Au₂₂₄(SR)₇₂ exhibits superior structural stability compared to Au₂₁₂(SR)₆₀. Spectroscopic and electronic analyses reveal that FCC-structured Au₂₂₄(SR)₇₂ retains molecular-state characteristics, proving that the FCC configuration alone is insufficient to impart metallic properties in large RS-AuNCs. Crucially, comparative studies between twinned-FCC Au₁₉₁(SR)₆₆ and pure-FCC Au₂₂₄(SR)₇₂ demonstrate that twinned configurations significantly lower the critical atom threshold for metallic behavior emergence. This work elucidates how core packing modes regulate electronic properties in RS-AuNCs, providing critical design principles for tailoring their optoelectronic characteristics.