Cocrystallization-driven stabilization of metastable nanoclusters: a case study of Pd1Au9

Abstract

The structural determination of metastable nanoclusters remains challenging, which impedes the in-depth understanding of their structural evolution. Herein, based on a case study of Pd₁Au₉, we present a “cocrystallization-driven stabilization” approach to stabilize the metastable nanocluster and then determine its atomically precise structure. The [Pd₁Au₉(TFPP)₇Br₂]⁺ nanocluster is unstable in solution and would spontaneously convert to Pd₂Au₂₃(TFPP)₁₀Br₇. The introduction of Au₁₁(TFPP)₇Br₃ nanocluster to the crystallization process of [Pd₁Au₉(TFPP)₇Br₂]⁺ gives rise to the cocrystallized Pd₁Au₉(TFPP)₆Br₃@Au₁₁(TFPP)₇Br₃, although the composition of Pd₁Au₉ changes from [Pd₁Au₉(TFPP)₇Br₂]⁺ to Pd₁Au₉(TFPP)₆Br₃ among this cocrystallization. With this approach, the overall structure of the metastable Pd₁Au₉ has been determined. Owing to the very similar cluster size and surface ligand environment between Au₁₁ and Pd₁Au₉, the obtained Pd₁Au₉@Au₁₁ cocrystal exhibits almost the same cell parameters as those of the single crystalized Au₁₁. Overall, the proposed “cocrystallization-driven stabilization” approach hopefully sheds light on the structural determination of more metastable nanoclusters.