1 research outputs found
Size Growth of Au<sub>4</sub>Cu<sub>4</sub>: From Increased Nucleation to Surface Capping
The size conversion of atomically precise metal nanoclusters
is
fundamental for elucidating structure-property correlations. In this
study, copper salt (CuCl)-induced size growth from [Au4Cu4(Dppm)2(SAdm)5]+ (abbreviated
as [Au4Cu4S5]+) to [Au4Cu6(Dppm)2(SAdm)4Cl3]+ (abbreviated
as [Au4Cu6S4Cl3]+)
(SAdmH = 1-adamantane mercaptan, Dppm = bis-(diphenylphosphino)methane)
was investigated via experiments and density functional theory calculations.
The [Au4Cu4S5]+ adopts a defective pentagonal bipyramid
core structure with surface cavities, which could be easily filled
with the sterically less hindered CuCl and CuSCy (i.e., core growth)
(HSCy = cyclohexanethiol) but not the bulky CuSAdm. As long as the
Au4Cu5 framework is formed, ligand exchange
or size growth occurs easily. However, owing to the compact pentagonal
bipyramid core structure, the latter growth mode occurs only for the
surface-capped [Au4Cu6(Dppm)2(SAdm)4Cl3]+ structure (i.e., surface-capped
size growth). A preliminary mechanistic study with density functional
theory (DFT) calculations indicated that the overall conversion occurred
via CuCl addition, core tautomerization, Cl migration, the second
[CuCl] addition, and [CuCl]-[CuSR] exchange steps. And the [Au4Cu6(Dppm)2(SAdm)4Cl3]+ alloy nanocluster exhibits aggregation-induced emission
(AIE) with an absolute luminescence quantum yield of 18.01% in the
solid state. This work sheds light on the structural transformation
of Au–Cu alloy nanoclusters induced by Cu(I) and contributes
to the knowledge base of metal-ion-induced size conversion of metal
nanoclusters