Structure and Electronic Structure Evolution of Thiolate-Protected Gold Nanoclusters Containing Quasi Face-Centered-Cubic Kernels

Abstract

A structure evolution map of face-centered cubic (fcc)-structured thiolate-ligand protected gold nanoclusters is outlined on the basis of total structure determination of a new 6e Au21(SR)15 (R = tert-butyl, t-Bu) cluster. The structural evolution map described some basic structural evolution patterns such as a triangle-Au3 and tetrahedron-Au4 associated gold-core evolution pattern and the periodic or symmetric growth of gold cores and ligand shells. According to the structural evolution map, a topological structure–electronic structure relationship is also proposed. The delocalized valence electronic properties of any fcc-structured gold clusters may be expressed as the linear combinations of the molecular orbitals of the fragment 2e units (Au3 + and Au4 2+). The structural disciplines and topological structure–electronic structure relationships reported in this work laid a basis for understanding the structural evolution and electronic structure of fcc-structured thiolate-protected gold nanoclusters. Particularly, the established structural evolution map provides a tool to explore new magic-sized clusters and cluster structures. In this work, a new fcc-structured 4e Au17(SR)13 and a new isomer structure of the 8e Au28(SR)20 cluster were predicted. The medium-sized fcc-structured gold clusters locating in the size range from 52 to 92 gold atoms and even larger-sized gold clusters can be also explored from the structural regularities described in the map.

Atomically Tailored Gold Nanoclusters for Catalytic Application

“…[1] Thes tructure of Au 25 (SR) 18 is made up of an icosahedral Au 13 kernel, which is protected by six dimeric staples motifs (i.e., -S À Au À S À Au À S-) (Figure 1A), [3b,c] and the atomic structure has enabled theoreticians to simulate its optical absorption spectrum and elucidate the origin of each electronic transition. [1] Thes tructure of Au 25 (SR) 18 is made up of an icosahedral Au 13 kernel, which is protected by six dimeric staples motifs (i.e., -S À Au À S À Au À S-) (Figure 1A), [3b,c] and the atomic structure has enabled theoreticians to simulate its optical absorption spectrum and elucidate the origin of each electronic transition.…”

“…Catalytic semihydrogenation of alkynes was compared for spherical Au 25 (SR) 18 and rod-shaped Au 25 (PPh 3 ) 10 (PA) 5 Cl 2 to study the effects of structure (mono-I h vs.b i-I h )a nd ligands (thiolate vs.a lkynyl/Cl). [53] Both supported ligand-on (i.e., without any treatment for removing ligands) Au 25 /TiO 2 catalysts showed high catalytic conversion for semihydrogenation of terminal alkynes with almost 100 %selectivity to the corresponding alkenes (Table 3).…”

“…Recent advances on the construction of astructure library of NCs have led to thiolate-protected NCs with the same number of Au atoms and the same number of ligands but with different structures.O ne example is the structural isomers of Au 38 -(PET) 24 , [8] which have the same formula but different structures.S ome structural isomers with different types of ligands,s o-called quasi-isomers,e xhibit different core and surface structures (e.g., Au 30 (SR) 18 ), [9] with adifference only in the carbon tail). The quasi-isomers sometimes show the same kernel structure while the surface staples show different patterns (e.g., Au 28 (SR) 20 ).…”

“…However,r ecent efforts on the "tailoring chemistry" of NCs have enabled the partial or entire structure of the NC to be modified while maintaining the size and/or core struc- Au 21 (SR) 15 [18] fcc-Au 12 fcc-Au 13 Au 21 S(SR) 15 [19] fcc-Au 12 Au 21 (SR) 12 (dppm) 2 [20] fcc-Au 15…”

“…Since the determination of its structure by crystallography,t he thiolate-protected Au 25 NC has been intensively studied in terms of the correlation between its atomic structure and properties. [1] Thes tructure of Au 25 (SR) 18 is made up of an icosahedral Au 13 kernel, which is protected by six dimeric staples motifs (i.e., -S À Au À S À Au À S-) ( Figure 1A), [3b,c] and the atomic structure has enabled theoreticians to simulate its optical absorption spectrum and elucidate the origin of each electronic transition.…”