Ultrabright Luminescence from Gold Nanoclusters: Rigidifying the Au(I)–Thiolate Shell

Abstract

Luminescent nanomaterials have captured the imagination of scientists for a long time and offer great promise for applications in organic/inorganic light-emitting displays, optoelectronics, optical sensors, biomedical imaging, and diagnostics. Atomically precise gold clusters with well-defined core-shell structures present bright prospects to achieve high photoluminescence efficiencies. In this study, gold clusters with a luminescence quantum yield greater than 60% were synthesized based on the Au22(SG)18 cluster, where SG is glutathione, by rigidifying its gold shell with tetraoctylammonium (TOA) cations. Time-resolved and temperature-dependent optical measurements on Au22(SG)18 have shown the presence of high quantum yield visible luminescence below freezing, indicating that shell rigidity enhances the luminescence quantum efficiency. To achieve high rigidity of the gold shell, Au22(SG)18 was bound to bulky TOA that resulted in greater than 60% quantum yield luminescence at room temperature. Optical measurements have confirmed that the rigidity of gold shell was responsible for the luminescence enhancement. This work presents an effective strategy to enhance the photoluminescence efficiencies of gold clusters by rigidifying the Au(I)-thiolate shell.

Zwitterion functionalized gold nanoclusters for multimodal near infrared fluorescence and photoacoustic imaging

“…This observation could be logically explained by the fact that high ligand coverage surrounding the metal core of the NCs improves the rigidity of the network leading to a strong fluorescence intensity. 46 Inversely, particle with a bigger metal core like for Au:Zw 2:1 and Au:Zw 5:1 with size > 4 nm will produce heat under illumination leading to more intense vibration and then stronger photoacoustic signal.…”

Fluorescent Gold Nanoclusters: Promising Fluorescent Probes for Sensors and Bioimaging

“…For example, Pyo et al presented a useful modifying method to significantly increase the luminescence efficiency of AuNCs via rigidifying the Au(I)-thiolate shell [67]. In the same year, Yao et al reported a simple functionalization strategy for synthesizing amphiphilic fluorescent AuNCs [68].…”

Advanced AuNMs as nanomedicine’s central goals capable of active targeting in both imaging and therapy in biomolecules

“…Nevertheless, the origin of emission in AuNCs still keeps unclear, posing a major hurdle for development of highly luminescent clusters. In 2015, Pyo et al [45] prepared Au 22 (glutathione) 18 clusters with a luminescence QY greater than 60% by rigidifying their Au shell with tetraoctylammonium cations. This study presents an effective strategy to enhance the luminescence efficiencies of AuNCs by optimizing the shell structure.…”