Here we report the single-crystal structure, experimental and theoretical characterization of a 41-metal atom Au-Ag alloy nanocluster [Au3Ag38(SCH2Ph)24X5]2- (1, X = Cl or Br). The nanocluster 1 is co-protected by thiolate and halogen atoms and features an all-metallic face-fused biicosahedral Au2@AuAg20 rod-like kernel enwrapped by the outermost Ag18(SCH2Ph)24X3 shell. Two sites on the surface of the biicosahedral kernel are partially occupied by Au and Ag atoms. The outer Ag18(SCH2Ph)24X3 shell is composed of two Ag6S6 cycles at the two poles and one Ag6S2X3 arc at the equator with both 2- and 3-coordinated Ag atoms, which has not been observed in gold or silver nanoclusters ever before. Theoretical calculations elucidate its electronic structure as well as optical properties, thus producing informative correlations between its structure and properties. This nanocluster exhibits near-infrared (NIR) emission around 825 nm. This work (i) snapshots a rare crystal structure of an Au-doped silver alloyed nanocluster; (ii) gives a deep insight to understand how the capping ligand or anions affect the structure of the alloy nanocluster; and (iii) provides precise information about gold atom doping site that is very significant in the recognition of potential active catalytic sites of the alloy nanoparticles.
Bibliographical noteFunding Information:
This work was supported by the NSFC (Grant No. 21201110 and 21571115), the Young Scholars Program of Shandong University (2015WLJH24), and the Fundamental Research Funds of Shandong University (22.214.171.124 and 2015JC045). C. M. A. is grateful to the Camille and Henry Dreyfus Foundation for a Camille Dreyfus Teacher-Scholar Award (2011-2016) and to the National Science Foundation for the grant CHE-1213771. The computing for this project was performed on the Beocat Research Cluster at Kansas State University, which is funded in part by NSF grants CNS-1006860, EPS-1006860, and EPS-0919443.
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