Correlating Kernel–Shell Structures with Optical Properties of Pt₁Ag₂₄ and Pt₁Ag₁₄ Nanoclusters

Abstract

With considerable attention focusing on metal nanoclusters, to explore the relationship of structures and their properties is of prime importance for designing novel functional nanoclusters and promoting their applications. Here we reported two novel alloy nanoclusters, [Pt1Ag24(SR)20]4– and Pt1Ag14(SR)6(PPh3)8 (H-SR: 2-chloro-4-fluorobenzenethiol), determined by X-ray crystallography. Interestingly, the two alloy nanoclusters have the same centered icosahedral Pt1Ag12 kernel, but shell structures are totally different due to the addition of PPh3 in the synthesis. Upon removal of the kernel, the shell of the Pt1Ag24 nanocluster is composed of two unique trefoil-like Ag6(SR)10 motifs, while the Pt1Ag14 nanocluster has six PPh3 and two Ag­(SR)3(PPh3) motifs. Furthermore, fluorescence spectroscopy and ultraviolet–visible absorption spectroscopy (UV–vis) were carried out to investigate the optical properties. The Pt1Ag24 nanocluster has near-infrared photoluminescence at 738 nm, whereas the emission of the Pt1Ag14 nanocluster is at 639 nm, demonstrating a blue shift of 99 nm. The two nanoclusters exhibit distinct optical fingerprints. Furthermore, the predicted partial density of states and UV–vis spectra assignments reveal the relationship of the crystal structures, electronic structures, and optical properties. These findings not only provide a feasible strategy to synthesize functional metal nanoclusters with distinctive structures but also give direct insight into understanding the structure–property correlations at the atomic level.

Synthesis and Optical Properties of Unique Pt1Ag24 Nanoclusters with Mixed Exterior Motif Structures

“…The shell is composed of three Ag 2 (SR) 3 (PPh 3 ) staple-like motifs and a unique trefoil-like Ag 6 (SR) 7 motif (Figure ). The Ag 6 (SR) 7 motif is made up of three pentagons and three triangles; this has been observed in the Au 1 Ag 26 and Pt 1 Ag 24 -B nanoclusters. No counterions were found in the crystal structure elucidation.…”

“…It is a surprise that we found the third structure of the Pt 1 Ag 24 nanocluster. To distinguish the three Pt 1 Ag 24 nanoclusters protected by different ligands (Figure S2), they are abbreviated as Pt 1 Ag 24 -A ([Pt 1 Ag 24 ­(SR) 18 ] 2– ), − Pt 1 Ag 24 -B ([Pt 1 Ag 24 ­(SR) 20 ] 4– ), and Pt 1 Ag 24 -C (Pt 1 Ag 24 (SR) 16 ­(PPh 3 ) 3 ) according to the reported time. Further structural analysis revealed that the Pt 1 Ag 24 -C nanocluster has a centered icosahedral Pt 1 Ag 12 kernel encapsulated by an open Ag 12 (SR) 16 ­(PPh 3 ) 3 shell.…”

“…Structural comparison of (a) [Pt 1 Ag 28 (SR) 18 ­(PPh 3 ) 4 ] 2+ (Pt 1 Ag 28 ), (b) Pt 1 Ag 24 (SR) 16 ­(PPh 3 ) 3 (Pt 1 Ag 24 -C), (c) [Pt 1 Ag 24 (SR) 18 ] 2– (Pt 1 Ag 24 -A), and (d) [Pt 1 Ag 24 (SR) 20 ] 4– (Pt 1 Ag 24 -B) nanoclusters. Color code: red, Pt; blue, Ag; orange, S; magenta, P.…”

“…Heteroatom doping of metal nanoclusters is an effective approach to purposefully tailor their physical or chemical properties for boosting their specific applications. − With regard to Ag nanoclusters, the accurate Pt dopant location and enhanced properties render doping a Pt atom into Ag nanoclusters remarkably attractive and crucial for the preparation of Ag-rich alloy nanoclusters. Despite that, a few Pt-doped Ag alloy nanoclusters protected by thiolates have been synthesized and structurally determined, including Pt 1 Ag 14 , Pt 1 Ag 24 , − Pt 1 Ag 26 , Pt 1 Ag 28 , − Pt 1 Ag 31 , and Pt 2 Ag 51 nanoclusters. The extremely limited reports on the Pt doping Ag nanoclusters suggest that doping the Pt atom into thiolate-protected Ag nanoclusters is still very challenging.…”

Atomically precise structures of Pt2(S-Adam)4(PPh3)2 complexes and catalytic application in propane dehydrogenation

“…18,19,[22][23][24] However, most sulfur atoms of platinum complexes were from elemental sulfur or sulfur compounds, not from bulky thiolates which were used as the sulfur source to synthesize structurally precise metal nanoclusters. 25,26 Significant progress in the synthesis and structure elucidation of Au, Ag and Cu nanoclusters stabilized by thiolates has been achieved, [27][28][29][30][31][32] but Pt nanoclusters were rarely reported. 33,34 Therefore, the precise synthesis and structure characterization of platinum complexes protected by bulky thiolates are of great significance to further explore the controllable synthesis and spatial arrangement of Pt nanoclusters stabilized by thiolates.…”