Luminescent Gold Nanoparticles with Size-Independent Emission
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- 作者：Dr. Jinbin Liu ; Paul N. Duchesne ; Dr. Mengxiao Yu ; Xingya Jiang ; Xuhui Ning ; Rodrigo D. Vinluan III ; Prof. Dr. Peng Zhang and Prof. Dr. Jie Zheng
- 刊名：Angewandte Chemie International Edition
- 出版年：2016
- 出版时间：July 25, 2016
- 年：2016
- 卷：55
- 期：31
- 页码：8894-8898
- 全文大小：2363K
- ISSN：1521-3773
文摘
Size-independent emission has been widely observed for ultrasmall thiolated gold nanoparticles (AuNPs) but our understanding of the photoluminescence mechanisms of noble metals on the nanoscale has remained limited. Herein, we report how the emission wavelength of a AuNP and the local binding geometry of a thiolate ligand (glutathione) on the AuNP are correlated, as these AuNPs emit at different wavelengths in spite of their identical size (ca. 2.5 nm). By using circular dichroism, X-ray absorption, and fluorescence spectroscopy, we found that a high Au−S coordination number (CN) and a high surface coverage resulted in strong AuI–ligand charge transfer, a chiral conformation, and 600 nm emission, whereas a low Au−S CN and a low surface coverage led to weak charge transfer, an achiral conformation, and 810 nm emission. These two size-independent emissions can be integrated into one single 2.5 nm AuNP by fine-tuning of the surface coverage; a ratiometric pH response was then observed owing to strong energy transfer between two emission centers, opening up new possibilities for the design of ultrasmall ratiometric pH nanoindicators.