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Total structure determination of surface doping [Ag46Au24(SR)32](BPh4)2 nanocluster and its structure-related catalytic property.

Wang S, Jin S, Yang S, Chen S, Song Y, Zhang J, Zhu M - Sci Adv (2015)

Bottom Line: The structure effect is widely present in the catalysis of alloy systems.This is the first case to find the structure effect in atomically precise alloy nanoclusters.Our work will benefit the basic understanding of bimetal distribution, as well as the structure-related catalytic property of alloy nanoclusters at the atomic level.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry and Center for Atomic Engineering of Advanced Materials, Anhui University, Hefei, Anhui 230601, People's Republic of China.

ABSTRACT
The structure effect is widely present in the catalysis of alloy systems. However, the surface structure of this system is still ambiguous because of the limitations of the current surface characterization tools. We reported the x-ray crystallographic structure of the first and the largest AgAu alloy nanocluster with a doping shell formulated as [Ag46Au24(SR)32](BPh4)2. This nanocluster consists of an achiral bimetallic Ag2@Au18@Ag20 core protected by a chiral Ag24Au6(SR)32 shell. The catalysis experiments further revealed that the surface structure affects the selectivity of products significantly. This is the first case to find the structure effect in atomically precise alloy nanoclusters. Our work will benefit the basic understanding of bimetal distribution, as well as the structure-related catalytic property of alloy nanoclusters at the atomic level.

No MeSH data available.


The three-shell structure of [Ag46Au24(SR)32]2+.(A and B) Top and side [Ag46Au24(SR)32](BPh4)2 views of the Ag2Au18 core (which is not connected with any thiolate ligands). (C and D) Top and side views of the Ag2@Au18@Ag20 core. (E and F) Top and side views of the Ag2@Au18@Ag20 core protected by Ag24Au6(SR)32 bimetallic shell. (G) Four bonding modes in the motif structure. Light green/blue/gray, silver; yellow, gold; red, sulfur.
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Figure 2: The three-shell structure of [Ag46Au24(SR)32]2+.(A and B) Top and side [Ag46Au24(SR)32](BPh4)2 views of the Ag2Au18 core (which is not connected with any thiolate ligands). (C and D) Top and side views of the Ag2@Au18@Ag20 core. (E and F) Top and side views of the Ag2@Au18@Ag20 core protected by Ag24Au6(SR)32 bimetallic shell. (G) Four bonding modes in the motif structure. Light green/blue/gray, silver; yellow, gold; red, sulfur.

Mentions: The structure of [Ag46Au24(SR)32]2+ nanocluster (counterion: two BPh4− ions) was solved by single-crystal x-ray crystallography (Fig. 1). The 70 metal atoms in this nanocluster are distributed in three shells. The central two silver atoms are surrounded by a tubbiness structure composed of 18 gold atoms (Fig. 2, A and B), which are capped with 20 silver atoms (Fig. 2, C and D). The 18 core gold atoms are distributed into three hexagons, and the overall shape resembles a barrel. Within this 18–gold atom shell, the average Au-Au distance is 2.7764 Å. The second shell consists of 20 silver atoms, with the top and bottom two silver atoms as covers of 18 core gold atoms. Among the remaining 18 silver atoms in the second shell, every six silver atoms form concentric hexagons with six gold atoms in the first shell. The average M-M distance in the Ag20Au18 core is 2.8821 Å. The Ag20Au18 core can also be considered as two types (types A and B) of layers (Fig. 2D): type A is one silver atom; type B is a hexagonal Au6 with another six vertex caps (Ag6). These two types of layers give rise to the 1:12:1:12:1:12:1 layers and can be described as nearly hexagonal close-packed A:B:A layering. Note that the similar 9:1:9 layer structure was also reported in [Au39(PPh3)14Cl6]Cl2 by Teo et al. (41).


Total structure determination of surface doping [Ag46Au24(SR)32](BPh4)2 nanocluster and its structure-related catalytic property.

Wang S, Jin S, Yang S, Chen S, Song Y, Zhang J, Zhu M - Sci Adv (2015)

The three-shell structure of [Ag46Au24(SR)32]2+.(A and B) Top and side [Ag46Au24(SR)32](BPh4)2 views of the Ag2Au18 core (which is not connected with any thiolate ligands). (C and D) Top and side views of the Ag2@Au18@Ag20 core. (E and F) Top and side views of the Ag2@Au18@Ag20 core protected by Ag24Au6(SR)32 bimetallic shell. (G) Four bonding modes in the motif structure. Light green/blue/gray, silver; yellow, gold; red, sulfur.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4643804&req=5

Figure 2: The three-shell structure of [Ag46Au24(SR)32]2+.(A and B) Top and side [Ag46Au24(SR)32](BPh4)2 views of the Ag2Au18 core (which is not connected with any thiolate ligands). (C and D) Top and side views of the Ag2@Au18@Ag20 core. (E and F) Top and side views of the Ag2@Au18@Ag20 core protected by Ag24Au6(SR)32 bimetallic shell. (G) Four bonding modes in the motif structure. Light green/blue/gray, silver; yellow, gold; red, sulfur.
Mentions: The structure of [Ag46Au24(SR)32]2+ nanocluster (counterion: two BPh4− ions) was solved by single-crystal x-ray crystallography (Fig. 1). The 70 metal atoms in this nanocluster are distributed in three shells. The central two silver atoms are surrounded by a tubbiness structure composed of 18 gold atoms (Fig. 2, A and B), which are capped with 20 silver atoms (Fig. 2, C and D). The 18 core gold atoms are distributed into three hexagons, and the overall shape resembles a barrel. Within this 18–gold atom shell, the average Au-Au distance is 2.7764 Å. The second shell consists of 20 silver atoms, with the top and bottom two silver atoms as covers of 18 core gold atoms. Among the remaining 18 silver atoms in the second shell, every six silver atoms form concentric hexagons with six gold atoms in the first shell. The average M-M distance in the Ag20Au18 core is 2.8821 Å. The Ag20Au18 core can also be considered as two types (types A and B) of layers (Fig. 2D): type A is one silver atom; type B is a hexagonal Au6 with another six vertex caps (Ag6). These two types of layers give rise to the 1:12:1:12:1:12:1 layers and can be described as nearly hexagonal close-packed A:B:A layering. Note that the similar 9:1:9 layer structure was also reported in [Au39(PPh3)14Cl6]Cl2 by Teo et al. (41).

Bottom Line: The structure effect is widely present in the catalysis of alloy systems.This is the first case to find the structure effect in atomically precise alloy nanoclusters.Our work will benefit the basic understanding of bimetal distribution, as well as the structure-related catalytic property of alloy nanoclusters at the atomic level.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry and Center for Atomic Engineering of Advanced Materials, Anhui University, Hefei, Anhui 230601, People's Republic of China.

ABSTRACT
The structure effect is widely present in the catalysis of alloy systems. However, the surface structure of this system is still ambiguous because of the limitations of the current surface characterization tools. We reported the x-ray crystallographic structure of the first and the largest AgAu alloy nanocluster with a doping shell formulated as [Ag46Au24(SR)32](BPh4)2. This nanocluster consists of an achiral bimetallic Ag2@Au18@Ag20 core protected by a chiral Ag24Au6(SR)32 shell. The catalysis experiments further revealed that the surface structure affects the selectivity of products significantly. This is the first case to find the structure effect in atomically precise alloy nanoclusters. Our work will benefit the basic understanding of bimetal distribution, as well as the structure-related catalytic property of alloy nanoclusters at the atomic level.

No MeSH data available.