The Structure and Optical Properties of the [Au₁₈(SR)₁₄] Nanocluster

Abstract

Decreasing the core size is one of the best ways to study the evolution from Au(I) complexes into Au nanoclusters. Toward this goal, we successfully synthesized the [Au18(SC6H11)14] nanocluster using the [Au18(SG)14] (SG=L-glutathione) nanocluster as the starting material to react with cyclohexylthiol, and determined the X-ray structure of the cyclohexylthiol-protected [Au18(C6H11S)14] nanocluster. The [Au18(SR)14] cluster has a Au9 bi-octahedral kernel (or inner core). This Au9 inner core is built by two octahedral Au6 cores sharing one triangular face. One transitional gold atom is found in the Au9 core, which can also be considered as part of the Au4(SR)5 staple motif. These findings offer new insight in terms of understanding the evolution from [Au(I)(SR)] complexes into Au nanoclusters.

Polymorphism of Phosphine-Protected Gold Nanoclusters: Synthesis and Characterization of a New 22-Gold-Atom Cluster

“…[ 57 ] The Au 20 pyramid was observed to be present in solution with triphenylphosphine (PPh 3 ) ligands using a synthetic procedure for gold nanoparticles. [ 58 ] The pyramidal structure and the electronic properties of the T d Au 20 (PPh 3 ) 4 cluster were shown computationally to be similar to those of the bare Au 20 . [ 58 ] However, in order to obtain large quantities of pure pyramidal Au 20 samples and investigate its interesting catalytic and optical properties, a high yield synthetic method is needed.…”

“…For gold cores with different nuclearity, or even the same nuclearity with different structures, the spectra will show totally different absorption peaks. For example, although both [Au 6 (dppp) 4 ] 2+ and [Au 7 (dppp) 4 ] 3+ have four 1,3-bis(diphenyl-phosphino)propane (dppp) ligands, their UV-Vis-NIR spectra show different peaks at 587 and 556 nm, respectively, [ 37 ] due to the different nuclearity. It has also been reported that the [Au 6 (dppp) 4 6 ] 3+ clusters all have structures consisting of a gold core with addition atoms outside the core (core+exo) and they all have different absorption features, when compared with the core-only Au nanoclusters of the same nuclearity.…”

“…For example, although both [Au 6 (dppp) 4 ] 2+ and [Au 7 (dppp) 4 ] 3+ have four 1,3-bis(diphenyl-phosphino)propane (dppp) ligands, their UV-Vis-NIR spectra show different peaks at 587 and 556 nm, respectively, [ 37 ] due to the different nuclearity. It has also been reported that the [Au 6 (dppp) 4 6 ] 3+ clusters all have structures consisting of a gold core with addition atoms outside the core (core+exo) and they all have different absorption features, when compared with the core-only Au nanoclusters of the same nuclearity. [ 45,63 ] On the other hand, for the same gold core structure, or even different gold cores that share the same gold building units, the UV-Vis spectra always show similar absorption features, regardless of the phosphine ligands.…”

Bonding properties of thiolate-protected gold nanoclusters and structural analogs from X-ray absorption spectroscopy

“…Since the elucidation of the Au 102 (SR) 44 NC in 2007 [19], the catalog of possible Au core geometries and stabilizing surface structures from solved crystal structures and DFT predictions has grown significantly [20]. To date, icosahedral, face-centered-cubic (FCC)-ordered and smaller Au core ( < 13 Au atoms) structures have been reported crystallographically for various Au n (SR) m sizes [19,[21][22][23][24][25][26][27][28][29][30]. A couple of selenolate-protected Au NCs have also been recently elucidated with icosahedral or small Au 8 core structures [31,32].…”

“…A couple of selenolate-protected Au NCs have also been recently elucidated with icosahedral or small Au 8 core structures [31,32]. In the last few years, a number of surface structures in addition to the monomeric and dimeric staple-like motifs were identified such as a trimeric staple-like motif [28], tetrameric staple-like motif [29,30], μ 3 sulfide coordination [25], bridging thiolate motif [24], and ring-like motifs (long Au-SR oligomers) [27,33]. Figure 1 presents the diversity of thiolate-protected Au NC structures.…”