Cyclopentanethiolato-Protected Au₃₆(SC₅H₉)₂₄ Nanocluster: Crystal Structure and Implications for the Steric and Electronic Effects of Ligand

Abstract

Thiolato-protected gold nanoclusters have acquired wide applications; however, on the fundamental science end there is still a lack of deep understanding of their high stability. Recent success in transforming the highly robust biicosahedral Au38(SCH2CH2Ph)24 nanocluster into an extremely stable tetrahedral Au36(SPh-(t)Bu)24 nanocluster raises an important question: Is the transformation due to the bulkiness effect of SPh-(t)Bu or the electronic conjugation effect of the aromatic ligand as opposed to the nonaromatic SCH2CH2Ph? Toward this goal, we report our success in the crystallization of a nonaromatic thiolato-protected Au36(SC5H9)24 nanocluster (where, SC5H9 = cyclopentanethiolato). Comparison of Au36(SC5H9)24 with the aromatic thiolato-protected Au36(SPh-(t)Bu)24 nanocluster rules out the thought that the face-centered cubic, tetrahedral structure of Au36(SPh-(t)Bu)24 is dictated by the aromatic ligand; it also reveals that the electronic conjugation effect in aromatic ligand makes the S-C bond shorter and stronger, and this affects the S-Au bonds, resulting in a larger separation between the staple motifs and the inner Au28 kernel. Overall, this work sheds some light on the major question of the specific roles of thiol ligand in determining the cluster size and structure.

Transformation Chemistry of Gold Nanoclusters: From One Stable Size to Another

“…We pursued the synthesis and crystallization of Au 36 protected by cyclopentanethiolate, Au 36 (SC 5 H 9 ) 24 . 76 The obtained crystal structure is essentially identical with that of Au 36 (TBBT) 24 . This rules out that the FCC structure of Au 36 (TBBT) 24 is dictated by the aromatic property of the ligand.…”

One-phase controlled synthesis of Au25nanospheres and nanorods from 1.3 nm Au : PPh3nanoparticles: the ligand effects

“…Unlike the etching reaction at r.t., some of the Au 25 (PPh 3 ) 10 (SC 2 H 4 Ph) 5 X 2 nanorods aggregate or decompose as a tiny black solid is found at the bottom of the flask after one day of etching (the solid cannot dissolve in organic solvents, such as CH 2 Cl 2 and toluene). 3A versus C) and Au 36 (SR) 24 (e.g., Au 36 (SC 6 H 11 ) 24 versus Au 36 (SPh t Bu)) 29 in this work and in previous literature. Further, we also test the etching reaction of Au 25 (PPh 3 ) 10 (SC 2 H 4 Ph) 5 X 2 with excess H-SC 2 H 4 Ph at 55°C and find that the Au 25 (PPh 3 ) 10 (SC 2 H 4 Ph) 5 X 2 nanorods gradually aggregate or decompose as the UV peaks at 680, 450 and 415 nm gradually decrease (Fig.…”

“…Au 25 (SNap) 18 nanospheres, the three optical absorption peaks are observed at ∼680, 500 and 400 nm (Fig. 29 In the MALDI-MS analysis, the Au 25 (SPh) 18 nanospheres show clean signals at m/z 6901.0 (theoretical molecular weight of Au 25 (SPh) 18 : 6889.1). 11 It is worthy to note that the observed shifted peak between the two Au 25 (SR) 18 nanospheres is largely attributed to the different electronic properties of H-SPh and H-SNap; this phenomenon also is found in the cases of the Au 36 (SR) 24 nanoclusters.…”

Surface Engineering of Au36(SR)24 Nanoclusters for Photoluminescence Enhancement

“…The UV–vis spectra in Figure A (normalized at λ 450 nm for PL purposes) confirm the conversion of Au 36 TBBT to Au 36 CPT from the blue shift of the absorbance peaks. The blue shift is due to the nonconjugation effects of the CPT; of note, the Au 36 structure is maintained since both the characteristic peaks and the spectral profiles of the Au 36 are maintained. Figure B compares the PL wavelengths of the ligand exchange of Au 36 TBBT with CPT over different time intervals.…”