Carboranealkynyl‐Protected Gold Nanoclusters: Size Conversion and UV/Vis–NIR Optical Properties
Jie Wang, Zhao‐Yang Wang, Shijun Li, Shuang‐Quan Zang, Thomas C. W. Mak
Abstract
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 [Au 28 (C 4 B 10 H 11 ) 12 (tht) 8 ] 3+ ( Au 28 , 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‐C 2 B 10 H 11 as the two‐in‐one reducing and protecting agent. Notably, Au 28 undergoes a complete transformation in methanol into a stable and smaller‐sized nanocluster [Au 23 (C 4 B 10 H 11 ) 9 (tht) 6 ] 2+ ( Au 23 ) 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. Au 28 and Au 23 both display optical absorption covering the UV/Vis–NIR range and NIR emission, which facilitates their potential application in the biomedical and photocatalytic fields.