High-yield synthesis and crystal structure of a green Au₃₀cluster co-capped by thiolate and sulfide

Abstract

A green gold-cluster, Au30S(StBu)18, was successfully prepared in high yield and crystallographically characterized. Each cluster consists of an Au22 core capped by a mixed layer of staple Au-thiolate units, bridging thiolates and a μ3-S(2-).

Enhancing stability through ligand-shell engineering: A case study with Au25(SR)18 nanoclusters

“…The as-synthesized Au 25 (MPA) 11 (Cyst) 7 NCs match these conditions, in which MPA and Cyst have similar chain lengths and opposite charges, and their ratio is also very close (11:7). As expected, the characteristic UV-vis absorption peaks of Au 25 (MPA) 11 (Cyst) 7 NCs are still distinct even after 120 h of storage in aqueous solution (Fig.…”

“…The coordination of mixed ligands was further confirmed by zeta-potential measurements. The surface charges of Au 25 (MPA) 11 (Cyst) 7 and Au 25 (MHA) [11][12][13][14] (Cyst) were less negative than those of Au 25 (MPA) 18 and Au 25 (MHA) 18 (Table 1). These values were expected as the binding between -COOH and -NH 2 groups could partially neutralize the surface charges of NCs.…”

“…If less -COO -···-NH 3 + pairs are formed on the NC surface, poorer stability of the NCs could be expected. It is reasonable that the latter three Au NC species (i.e., Au 25 (MHA) 12 (Cyst) 6 , Au 25 (MHA) 13 (Cyst) 5 , and Au 25 (MHA) 14 (Cyst) 4 ) may exhibit relatively poorer stability compared with Au 25 (MHA) 11 (Cyst) 7 .…”

“…In two earlier reports, during the CO-directed synthesis of monothiolate-protected Au 25 NCs, Luo et al [54] and Yu et al [49] observed that the synthesis of Au 25 NCs is thermodynamically driven by a size-focusing process 11 (Cyst) 7 could be the most thermodynamically favorable product through a ligand-focusing process. We speculated that Au 25 NCs with polydisperse ligand compositions could be initially formed; however, only Au 25 (MPA) 11 (Cyst) 7 NCs will survive because of its better stability than the other NC species in solution. The creation of monodispersed Au 25 (MPA) 11 (Cyst) 7 NCs revealed that engineering the surface ligands of metal NCs can improve their stability.…”

“…Thiolate-protected gold nanoclusters (or thiolated Au NCs for short) are ultra-small Au particles (usually < 2 nm in core size) stabilized by many thiolate ligands [1][2][3][4][5][6][7]. Because of strong quantum confinement effects in the sub-2-nm size range, thiolated Au NCs exhibit some interesting molecular-like properties such as quantized charging [8], HOMO-LUMO transitions [9], and strong luminescence [10][11][12], which make them promising in the fields of optoelectronics [13,14], catalysis [15][16][17], energy conversion [18,19], sensing [20,21], biomedicine [22][23][24][25], and others [26,27].…”