Identification of Intermediate Au₂₂(SR)₄(SR′)₁₄ Cluster on Ligand-Induced Transformation of Au₂₅(SR)₁₈ Nanocluster

Abstract

We report the ligand-exchange-induced transformation from an icosahedral Au 25 (SR) 18 cluster (where SR = 2-phenylethanethiol (PET)) to a bitetrahedral Au 22 (SR) 4 (SR′) 14 cluster (where SR′ = 4-tert-butylbenzenethiol (TBBT)). This partial exchange of the ligands was achieved by controlling the concentration of the incoming TBBT ligand. Being a bulky and aromatic ligand, TBBT can efficiently distort the atomic structure of the Au 25 PET 18 cluster, resulting in Au 22 (PET) 4 (TBBT) 14 , which is highly stable and considered to be an intermediate with a bitetrahedral structure. Time-dependent mass spectrometry and optical spectroscopy revealed the dissociation of the parent cluster and gave a deep insight on the ligand-exchange mechanism. Theoretical calculations and extended Xray absorption fine structure studies confirm the formation of the Au 22 structure. Identifying the atomic structure of the intermediate species opens a new avenue to study the transformation of one cluster to another.

Thiolate‐Protected Metal Nanoclusters: Recent Development in Synthesis, Understanding of Reaction, and Application in Energy and Environmental Field

“…Pattern 3 is called a ligand‐exchange‐induced structure transformation (LEIST), which is a reaction that has been widely used for the creation of new metal NCs in recent years. [ 3,158,168,270–300 ] Representative metal NCs synthesized by LEIST are summarized in Table 4 . For this reaction, many studies on the mechanism have been conducted to date.…”

Transformation of Atomically Precise Nanoclusters by Ligand-Exchange

“…The ligand-exchange reaction between Au 25 (SC 2 H 4 Ph) 18 and HSPh t Bu ligand can yield different cluster products through meticulously controlling the reaction conditions such as the temperature, the reaction time, and the thiol feeding ratio (Figure ). − Specifically For LEIST from Au 25 (SC 2 H 4 Ph) 18 to Au 20 (SPh t Bu) 16 : To the toluene solution of Au 25 (SC 2 H 4 Ph) 18 , excess HSPh t Bu ligand was added in (150:1 molar ratio of the HSPh t Bu to the SC 2 H 4 Ph in Au 25 (SC 2 H 4 Ph) 18 ), and the ligand-exchange process proceeded at 40 °C for 8 h (Figure A). Among the ligand-exchange, the icosahedral Au 13 kernel was etched into a bitetrahedral Au 7 kernel (two tetrahedra share a vertex Au atom), and this Au 7 kernel was further stabilized by an octameric Au 8 (SR) 8 ring motif, a trimeric Au 3 (SR) 4 staple motif, and two monomeric Au 1 (SR) 2 staple motifs, making up the overall structure of Au 20 (SPh t Bu) 16 (Figure A) .…”

“… For LEIST from Au 25 (SC 2 H 4 Ph) 18 to Au 22 (SC 2 H 4 Ph) 4 (SPh t Bu) 14 : Reacting the Au 25 (SC 2 H 4 Ph) 18 with an equal-molar HSPh t Bu ligand at 80 °C for 17 h yielded a smaller Au 22 (SC 2 H 4 Ph) 4 (SPh t Bu) 14 nanocluster. However, the experimental structure of Au 22 (SC 2 H 4 Ph) 4 (SPh t Bu) 14 remained undetermined but was just theoretically predicted as a prolate Au 8 kernel plus Au 14 (SR) 18 motif structures (Figure C) . By analyzing the time-dependent MALDI-MS spectra of the ligand-exchange reaction, both Au 22 (SC 2 H 4 Ph) 18– m (SPh t Bu) m and Au 28 (SC 2 H 4 Ph) 18– n (SPh t Bu) n +2 were generated as intermediates (in 5 min, 1 h, and 7 h mass spectra), but only the Au 22 (SC 2 H 4 Ph) 4 (SPh t Bu) 14 remained as the final product in the 17 h mass spectra, demonstrating the high thermal-stability of this molecule .…”

Redox-Induced Interconversion of Two Au8 Nanoclusters: the Mechanism and the Structure–Bond Dissociation Activity Correlations

“…Structure and property response of nanomaterials to environmental stimuli (such as changes in solvent, temperature, etc. ) − is fundamental to their practical applications in bioclinics, sensing, and catalysis. − Nevertheless, precise understanding on the origin of the stimuli response and the key driving forces, which will undoubtedly boost the development of more functional materials, has long been challenging due to the poly-dispersity issues. In this context, the metal (Au, Ag, etc.)…”