Tuning the Electrical Properties through Metal-Ion-Mediated Assembly in Au₂₅ Nanocluster-Based Frameworks

Au nanoclusters (NCs), with discrete electronic structures and tunable properties, are promising building blocks for nanoelectronics. However, maximizing their potential requires a deeper understanding of precise control over intercluster interactions, which is crucial for charge transport. Here, we leverage coordination chemistry to fine-tune intercluster distances in NC-based frameworks by incorporating coordinating metal ions (Mg²⁺, Co²⁺, Ni²⁺, or Cu²⁺) into [Au₂₅(p-HMBA)₁₈]^- NCs. Single-crystal X-ray diffraction reveals that four isostructural frameworks have systematic lattice parameter variations, driving a 31-fold enhancement in the electrical conductivity. Density functional theory calculations further reveal semiconductor-like electronic structures and highlight that Cu²⁺-coordinated frameworks exhibit more efficient charge transport due to the presence of Cu 3d states near the Fermi level. This atomic-level investigation of intercluster distance effects and electrical property tuning through coordinating ion incorporation establishes design principles for engineering electronic properties in NC frameworks, enabling the development of precisely tunable and high-performance nanoelectronic materials.