An Unprecedented Kernel Growth Mode and Layer-Number-Odevity-Dependent Properties in Gold Nanoclusters

Kernel atoms of Au nanoclusters are packed layer-by-layer along the [001] direction with every full (001) monolayer composed of 8 Au atoms (Au₈ unit) in nanoclusters with formula of Au_8n+4 (TBBT)_4n+8 (n is the number of Au₈ units; TBBTH=4-tert-butylbenzenelthiol). It is unclear whether the kernel atoms can be stacked in a defective-layer way along the [001] direction during growth of the series of nanoclusters and how the kernel layer number affects properties. Now, a nanocluster is synthesized that is precisely characterized by mass spectrometry and single-crystal X-ray crystallography, revealing a layer stacking mode in which a half monolayer composed of 4 atoms (Au₄ unit) is stacked on the full monolayer along the [001] direction. The size and the odevity of the kernel layer number influence the properties (polarity, photoluminescence) of gold nanoclusters. The obtained nanocluster extends the previous formula from Au_8n+4 (TBBT)_4n+8 to Au_4n+4 (TBBT)_2n+8 (n is the number of Au₄ units).