Homoleptic Alkynyl-Protected [Ag8Cu7(tBuC≡C)12]+ Nanoclusters: Synthesis, Structure and Ligand Exchange Induced Transformation

Abstract

Alloyed nanoclusters have been widely reported, but controllable synthesis of predesigned nanoclusters with specific structures remains challenging. We used [Cu(MeCN)₄]PF₆ intercept (Ag^tBuC≡C)_n polymer to form Ag(I)-Cu(II) oligomer precursors which serve as the starting point of co-reduction reaction, leading to the generation of a new [Ag₈Cu₇(^tBuC≡C)₁₂]PF₆ (Ag₈Cu₇) nanocluster. Single-crystal diffraction result reveals its Cu@Ag₈@Cu₆(^tBuC≡C)₁₂ three-layer structure similar to the previously reported Ag₉Cu₆ nanocluster except for the different core atom and shorter bond distance around. The identification of Ag₈Cu₇ was further confirmed by ESI-MS, XPS, PXRD, and TG characterizations. Besides, the nonemissive Ag₈Cu₇ cluster was subject to ligand exchange of bulky ligand 3,5-bis(trifluoromethyl)phenylacetylide (ArC ≡ CH) giving a novel Ag₁₀Cu₄(ArC ≡ C)₁₄(DPPB)₂ (Ag₁₀Cu₄) with a 634 nm red light emission, which provides another example of the breakage-reassembly mechanism.