In Situ Two-Phase Ligand Exchange: A New Method for the Synthesis of Alloy Nanoclusters with Precise Atomic Structures

A new method termed “in situ two-phase ligand exchange” was developed to obtain alloy nanoclusters. With this approach, a series of alloy nanoclusters were obtained for the first time, including Au20Ag1(SR)15, Au21–xAgx(SR)15 (x = 4–8), Au21–xCux(SR)15 (x = 0, 1), and Au21–xCux(SR)15 (x = 2–5) (R = tert-butyl). Interestingly, single-crystal X-ray crystallography (SC-XRD) shows that their frameworks are all alike except for Au21–xCux(SR)15 (x = 2–5), indicating that more Cu dopants alter the structure. Au21–xCux(SR)15 (x = 2–5) exhibits a significantly different configuration. The optical absorption spectra of these bimetal nanoclusters (NCs) show distinct characteristic peaks, indicating that the metal-doping remarkably affects the electronic structure of NCs. The DFT calculations were also employed for determination of NC 1–3 frameworks and understanding their optical properties.