Limits...
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.


Chiral structure of [Ag46Au24(SR)32](BPh4)2 nanocluster.(A and B) Top view of the shell structure without the AuSR unit and the top/bottom RS group (A) and with the addition of three AuSR groups (B). (C and D) Top views of two-enantiomer shell. (E and F) Top views of two-enantiomer nanoclusters without H and C atoms. Gray/green, silver; yellow, gold; red/blue, sulfur.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4643804&req=5

Figure 3: Chiral structure of [Ag46Au24(SR)32](BPh4)2 nanocluster.(A and B) Top view of the shell structure without the AuSR unit and the top/bottom RS group (A) and with the addition of three AuSR groups (B). (C and D) Top views of two-enantiomer shell. (E and F) Top views of two-enantiomer nanoclusters without H and C atoms. Gray/green, silver; yellow, gold; red/blue, sulfur.

Mentions: As shown in Fig. 2 (C and D), the metal core of this nanocluster is achiral. To further identify the origin of chirality in this nanocluster, we remove the metal core, the AuRS unit in the shell, as well as the top and bottom RS groups. As shown in Fig. 3A, the point group of a Ag-RS shell is D3d after removing these groups, suggesting that this shell is achiral. The tilted AuSR units reduce the symmetry by eliminating three σd, with a symmetric center remaining (Fig. 3B). The top and bottom RS groups give rise to chirality (Fig. 3, C and D) in the [Ag46Au24(SR)32](BPh4)2 nanocluster (Fig. 3, E and F). The findings on chirality in this nanocluster are remarkable. In general, two major effects might be responsible for the chiral of homometal nanoclusters: (i) the chiral ligands can induce the chiral of achiral nanoclusters (52) and (ii) asymmetric arrangement of an RS-Au-RS group on the achiral gold nanoclusters (39, 48, 49, 50, 53). In our case, asymmetric arrangement of the two RS groups changed the chirality of the nanoclusters.


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)

Chiral structure of [Ag46Au24(SR)32](BPh4)2 nanocluster.(A and B) Top view of the shell structure without the AuSR unit and the top/bottom RS group (A) and with the addition of three AuSR groups (B). (C and D) Top views of two-enantiomer shell. (E and F) Top views of two-enantiomer nanoclusters without H and C atoms. Gray/green, silver; yellow, gold; red/blue, sulfur.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 3: Chiral structure of [Ag46Au24(SR)32](BPh4)2 nanocluster.(A and B) Top view of the shell structure without the AuSR unit and the top/bottom RS group (A) and with the addition of three AuSR groups (B). (C and D) Top views of two-enantiomer shell. (E and F) Top views of two-enantiomer nanoclusters without H and C atoms. Gray/green, silver; yellow, gold; red/blue, sulfur.
Mentions: As shown in Fig. 2 (C and D), the metal core of this nanocluster is achiral. To further identify the origin of chirality in this nanocluster, we remove the metal core, the AuRS unit in the shell, as well as the top and bottom RS groups. As shown in Fig. 3A, the point group of a Ag-RS shell is D3d after removing these groups, suggesting that this shell is achiral. The tilted AuSR units reduce the symmetry by eliminating three σd, with a symmetric center remaining (Fig. 3B). The top and bottom RS groups give rise to chirality (Fig. 3, C and D) in the [Ag46Au24(SR)32](BPh4)2 nanocluster (Fig. 3, E and F). The findings on chirality in this nanocluster are remarkable. In general, two major effects might be responsible for the chiral of homometal nanoclusters: (i) the chiral ligands can induce the chiral of achiral nanoclusters (52) and (ii) asymmetric arrangement of an RS-Au-RS group on the achiral gold nanoclusters (39, 48, 49, 50, 53). In our case, asymmetric arrangement of the two RS groups changed the chirality of the nanoclusters.

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.