Carboranealkynyl‐Protected Gold Nanoclusters: Size Conversion and UV/Vis–NIR Optical Properties

Abstract

Structure evolution has become an effective way to assemble novel monolayer‐protected metal nanomolecules. However, evolution with alkynyl‐stabilized metal clusters still remains rarely explored. Herein, we present a carboranealkynyl‐protected gold nanocluster [Au28(C4B10H11)12(tht)8]3+ (Au28, tht=tetrahydrothiophene) possessing an open‐shell electronic structure with 13 free electrons, which was isolated by a facile self‐reduction method with 9‐HC≡C‐closo‐1,2‐C2B10H11 as the two‐in‐one reducing and protecting agent. Notably, Au28 undergoes a complete transformation in methanol into a stable and smaller‐sized nanocluster [Au23(C4B10H11)9(tht)6]2+ (Au23) bearing 12 valence electrons and crystal‐field‐like split superatomic 1D orbitals. The transformation process was systematically monitored with ESI‐MS and UV/Vis absorption spectra. Au28 and Au23 both display optical absorption covering the UV/Vis–NIR range and NIR emission, which facilitates their potential application in the biomedical and photocatalytic fields.

Interactions of Metal Nanoclusters with Light: Fundamentals and Applications

“…The ligand body, especially the part connected to the anchoring point, plays an important role in the vibration and rotation of the NC molecules. [53,54] Several factors, such as conjugation and steric hindrance may restrict the free vibration or rotation of NCs. [55,56] Therefore, for metal NCs with different types of ligand body, the vibration and rotation states may be different.…”

Levonorgestrel-protected Au8 and Au10 clusters with different antimicrobial abilities

“…1,2 However, when the size of Au nanoparticles (AuNPs) decreases to close to 1 nm, these nanoclusters (AuNCs) begin to hold discrete electronic states, which bring with them intriguing molecularlike properties, such as quantized charging and strong luminescence, that may be useful for different applications. [3][4][5][6][7][8][9] In biological applications, several recent studies have shown that AuNCs (with core sizes less than 2 nm) could display enhanced antimicrobial ability. [10][11][12] Compared with the most studied silver-based antimicrobial agents, whose activity is mainly derived from the generation of Ag + ions, [13][14][15][16][17] gold is more stable and could maintain its desirable biocompatibility in the mammalian cell model, [18][19][20] thus possessing a brighter future in clinical translation.…”

“…34 As for the surface charge, Xie's group generated a family of AuNCs with the same number of gold atoms but different surface properties and found that more negatively charged AuNCs would produce more reactive oxygen species (ROS), leading to a higher bacterial killing efficiency. 33 Due to the complexity of the interaction between metal nanoclusters and organisms, 6,35–39 we speculate that there might exist other factors affecting the antibacterial activity of AuNCs. In this case, atomic-precise AuNCs could provide a good platform to explore the relationship between the structure and biological activity.…”

Synthesis of metal nanoclusters and regulation of their photoluminescent properties

“…而大分子配体保护的金属纳米团簇具有一定的 刚性, 使其显现出更加优异的稳定性和光致发光性 能 [20] . 同时, 大分子配体相比于小分子配体具有更加 [30] ; (c) Au n (SR) m 团簇向Au(I)-SR配合物的转变 [32] (网络版彩图) 图 2 (a) 由不同膦配体保护的三种富氢银纳米团簇结构示 意图 [34] ; (b) 二膦保护的Au 18 团簇结构示意图 [35] ; (c) 开口式 二十面体Au 13 团簇(左)和心形Au 8 团簇(右)结构示意图 [36] ; (d) 双膦配体保护的鸟笼状(左)和冠状(右)Au 11 团簇结构示意 图 [37] (网络版彩图) [39] ; (d) 碳硼烷炔保护的Au 28 和Au 23 团簇结构示意图 [40] ; (e) Cu 23 纳米团簇结构沿C3轴的侧视(左)和俯视(右)视角 [41] ; (f) SD/Cu23a头对尾双层结构和SD/Cu23b头对头双层结构的示 意图 [41] (网络版彩图) 2+ 结构示意图 [42] ; 样的团簇结构和性质 [46~49] . Aljuhani等 [46] 2+ 的结构示 意图 [46] ; (b) 三氟甲磺酸和叔丁基乙炔共同保护的Ag 43 纳米 团簇结构(左)、Ag 43 核的同心三壳层结构(中)和两种表面配 体的配位方式(右) [47] ; (c) 炔基和有机膦共同保护的金纳米 团簇[Au 40 (PhC≡C) 20 (DPPM) 4 ](SbF 6 ) 4 结构示意图 [48] ; (d) PET、氢化物和氯化物共同保护的盒状双阴离子铜纳米团 簇结构示意图 [49] (网络版彩图) 性. Li等 [57] 稳定 的7核银纳米团簇结构示意图 [61] (网络版彩图) [70] 和配体效应 [71,72] 对金 属纳米团簇发光的影响).…”

“…Figure 3 (a) Schematic structures of all-alkynyl-protected face-centered cubic gold nanoclusters Au 110 (left), peripheral 24 Au(C≡CR) 2 stapled monomers (top right) and face-centered cubic Au 86 kernel (bottom right) [38]; (b) C3 axis view (left) , top view (top right) and side view (bottom right) perspectives of silver nanocluster (C 7 H 17 ClN) 3 [Ag 112 Cl 6 (C≡CAr) 51 ] structure protected by a large alkynyl group [39]; (c) schematic diagram of concentric four-shell structure and four alkyne-silver coordination modes of silver nanocluster (C 7 H 17 ClN) 3 -[Ag 112 Cl 6 (C≡CAr) 51 ] [39]; (d) schematic structure of Au 28 and Au 23 clusters protected by carborane[40]; (e) side view (left) and top view (right) perspectives of Cu 23 nanocluster structure along C3 axis[41]; (f) schematic diagram of SD/Cu23a head-to-tail double-layer structure and SD/Cu23b head-to-head double-layer structure[41] (color online).…”