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

• Published in: Angewandte Chemie International Edition Vol. 60; no. 11; pp. 5959 - 5964
• Main Authors: Wang, Jie, Wang, Zhao‐Yang, Li, Shi‐Jun, Zang, Shuang‐Quan, Mak, Thomas C. W.
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 08.03.2021
• Edition: International ed. in English
• Subjects: Absorption; Absorption spectra; carboranes; Electronic structure; Evolution; Free electrons; Gold; gold nanoclusters; Metal clusters; Nanoclusters; NIR emission; Optical properties; self-reduction syntheses; structure evolution; NIR emission; structure evolution; self-reduction syntheses; carboranes; gold nanoclusters
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202013027

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. A carboranealkynyl‐protected gold nanocluster Au28 possessing an open‐shell electronic structure with 13 valence electrons was isolated through a facile self‐reduction method in which it undergoes a complete transformation in methanol into a smaller‐sized cluster Au23 bearing 12 valence electrons and crystal‐field‐like split superatomic 1D orbitals. Au28 and Au23 both display optical absorption covering the UV/Vis–NIR range and NIR emission.