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Controlling the Structure, Properties and Surface Reactivity of Clickable Azide-Functionalized Au25 (SR)18
Praveen N Gunawardene1, Julia Martin1, Jonathan M Wong1
1Department of Chemistry and Centre for Advanced Materials and Biomaterials Research, Western University London, Ontario, N6A 5B7, Canada.
Angewandte Chemie (International Ed. in English)
|May 17, 2022
Summary
This study synthesized azide-functionalized gold nanoclusters, exploring how ligand position affects their reactivity and stability in click chemistry. The para-isomer showed the highest reaction rates, while the ortho-isomer was unstable.
Area of Science:
- Nanomaterials Chemistry
- Surface Science
- Supramolecular Chemistry
Background:
- Thiolate-protected gold nanoclusters offer tunable properties for advanced applications.
- Post-assembly surface modification is key to fine-tuning nanocluster structure-property relationships.
- Azide-alkyne cycloaddition is a powerful tool for bioconjugation and materials science.
Purpose of the Study:
- To synthesize regioisomeric azide-functionalized gold nanoclusters ([Au25(SCH2CH2-C6H4-N3)18]1-) for studying structure-property correlations.
- To investigate the impact of ligand regioisomerism on cluster-surface strain-promoted alkyne-azide cycloaddition (CS-SPAAC) reactivity and stability.
- To elucidate the molecular structures of these modified nanoclusters using single-crystal X-ray diffraction.
Main Methods:
- Synthesis of ortho, meta, and para regioisomers of azide-functionalized [Au25(SCH2CH2-C6H4-N3)18]1- nanoclusters.
- Characterization of nanocluster optical and electrochemical properties.
- Investigation of CS-SPAAC reactivity with strained alkynes.
- Single-crystal X-ray diffraction analysis of neutral nanocluster forms.
Main Results:
- Synthesized three regioisomers of azide-functionalized gold nanoclusters.
- Observed that electrochemical properties correlate with the azido group's position.
- Demonstrated varying CS-SPAAC reaction rates and stabilities based on ligand isomerism; the para-isomer exhibited the highest reactivity, while the ortho-isomer showed instability.
- Determined molecular structures revealing correlations between the central core and azido moiety position.
Conclusions:
- Regioisomerism of surface ligands significantly influences the electrochemical properties and CS-SPAAC reactivity of gold nanoclusters.
- The position of the azido group dictates the stability and reaction kinetics of the nanocluster system.
- Single-crystal X-ray diffraction provides crucial insights into the structural basis of these observed structure-property relationships.
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