Control over Ligand-Exchange Positions of Thiolate-Protected Gold Nanoclusters Using Steric Repulsion of Protecting Ligands

Abstract

Organic ligands on gold nanoclusters play important roles in regulating the structures of gold cores. However, the impact of the number and positions of the protecting ligands on gold-core structures remains unclear. We isolated thiolate-protected Au 25 cluster anions, [Au 25 (SC 2 Ph) 17 (Por) 1 ] − and [Au 25 (SC 2 Ph) 16 (Por) 2 ] − (SC 2 Ph = 2-phenylethanethiolate), obtained by ligand exchange of [Au 25 (SC 2 Ph) 18 ] − with one or two porphyrinthiolate (Por) ligands as mixtures of regioisomers. The ratio of two regioisomers in [Au 25 (SC 2 Ph) 17 (Por) 1 ] − as measured by 1 H NMR spectroscopy revealed that the selectivity could be controlled by the steric hindrance of the incoming thiols. Extended X-ray absorption fine structure studies of a series of porphyrin-coordinated gold nanoclusters clarified that the Au 13 icosahedral core in the Au 25 cluster was distorted through steric repulsion between porphyrin thiolates and phenylethanethiolates. This paper reveals interesting insights into the importance of the steric structures of protecting ligands for control over core structures in gold nanoclusters.

All-alkynyl-protected coinage metal nanoclusters: from synthesis to electrocatalytic CO2reduction applications

“…59 Ligand exchange can transform the cluster size, morphology, composition, and structural arrangement and also introduce new chemical/physical properties. 49,60,61 Pioneering work using this method to prepare all-alkynyl-protected metal clusters was done by Tsukuda et al In 2011, by reacting polyvinylpyrrolidone stabilized Au nanoclusters with a series of alkynyl molecules, several magic clusters such as Au 54 (PA) 26 , Au 94 (PA) 38 , and Au 110 (PA) 40 can be identified in the mass spectra of the final mixture product. 62 In 2019, the same group reported a quasi ligand exchange reaction, in which hydride-doped [HM@Au 8 -(PPh 3 ) 8 ] + (M = Pd, Pt) reacting with Au(I)-alkynyl oligomer to yield [MAu 24 (C CAr F ) 18 ] 2À clusters.…”

Insights into the effect of regulation of molecular composition on the properties of (AuAg)9clusters

“…28–32 So, the control of the cluster metal and ligand can tailor the properties of nanoclusters and help clarify the effect of each component on their performance and will enable us to better understand the nanoclusters. 19–35…”

“…[11][12][13][14][15][16][17][18] For efficiently controlling the construction and compositions of nanoclusters at the atomic level to tune their properties, an alloying strategy for the manipulation of metal composition and a ligand-engineering strategy for the regu-lation of the surface structure have often been reported. [19][20][21][22][23][24] Asymmetrically doping a platinum atom into Au 38 can change its electron configuration and reactivity during electrocatalysis. 25 The metallic compositions of nanoclusters can dictate whether their photoluminescence is fluorescence or phosphorescence for the Au 5 Ag 11 and Pt 1 Ag 16 nanoclusters.…”

“…[28][29][30][31][32] So, the control of the cluster metal and ligand can tailor the properties of nanoclusters and help clarify the effect of each component on their performance and will enable us to better understand the nanoclusters. [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] Structurally, the alloy nanocluster [Au 4 Ag 5 (SAdm) 6 (Dppm) 2 ] (BPh 4 ) encompasses metals (Au 4 Ag 5 ), a surface thiol ligand (SAdm-), and a phosphine ligand (Dppm), 36 and the investigations of the control of the metals and ligands based on [Au 4 Ag 5 (SAdm) 6 (Dppm) 2 ](BPh 4 ) will provide an opportunity to explore the effects of regulation of metals and surface ligands on electronic and optical properties.…”

Co-reactant-Free Transformation in Atomically Precise Metal Nanoclusters

“…LEIST is a highly versatile methodology that has helped in obtaining unique NCs which were not accessible through conventional methods, namely, the modified Brust–Schiffrin method and size-focusing methods. − There are several examples where LEIST brings forth opportunities in functionalizing and tailoring the surface structure via understanding the gradual structural change in the parent NCs when treated at high temperature with excess free ligands. − For example, an extensive ligand exchange on Au 25 (SR) 18 NC with different thiolate ligands showed that Au 25 could accommodate a wide variety of thiolate ligands. − Ligand exchange performed on the Au 25 (SG) 18 (SG = glutathione) NC with functionalized glutathione also revealed modulated optical properties of Au 25 (SG) 18 . The observation of enhancement in stability of Au 25 (SR) 18 NC upon ligand exchange with selenolate ligand underlies the importance of LEIST in obtaining desired properties. , A rapid ligand exchange on the [Ag 44 (SR) 30 ] 4– NC with a variety of thiolates was reported by Bakr and co-workers .…”