Interdependence between nanoclusters AuAg24 and Au2Ag41

Abstract

Whole series of nanoparticles have now been reported, but probing the competing or coexisting effects in their synthesis and growth remains challenging. Here, we report a bi-nanocluster system comprising two ultra-small, atomically precise nanoclusters, AuAg24(SR)18− and Au2Ag41(SR)26(Dppm)2+ (SR = cyclohexyl mercaptan, Dppm = bis(diphenylphosphino)-methane). The mechanism by which these two nanoclusters coexist is elucidated, and found to entail formation of the unstable AuAg24(SR)18−, followed by its partial conversion to Au2Ag41(SR)26(Dppm)2+ in the presence of di-phosphorus ligands, and an interdependent bi-nanocluster system is established, wherein the two oppositely charged nanoclusters protect each other from decomposition. AuAg24(SR)18 and Au2Ag41(SR)26(Dppm)2 are fully characterized by single crystal X-ray diffraction (SC-XRD) analysis – it is found that their co-crystallization results in single crystals comprising equimolar amounts of each. The findings highlight the interdependent relationship between two individual nanoclusters, which paves the way for new perspectives on nanocluster formation and stability.