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Thesis Format

Integrated Article

Degree

Master of Science

Program

Chemistry

Supervisor

Workentin, Mark S.

2nd Supervisor

Corrigan, John F.

Co-Supervisor

Abstract

Azide-functionalized [Au25(SR)18] gold nanoclusters [Au25(SCH2CH2C6H4-N3)18]- are able to undergo post-assembly surface modification via click reaction chemistry. In this study, we report the reaction of the azide cluster, (Oct4N)[Au25(SCH2CH2-p-C6H4N3)18] (AuNC-azide) with triarylphosphine bidentates. The -N3 groups on AuNC-azide undergo Staudinger reactions with PPh3, yielding surface -C6H4N=PPh3 at room temperature under inert atmosphere: this reaction is quite selective towards formation of -C6H4N=PPh3 when using up to 14 equivalents of PPh3. However, when a greater number of equivalents of triphenylphosphine is used, surface displacement of thiolate ligands also occurred in competition with the Staudinger reaction. Reactions of AuNC-azide with the bidentate phosphine ligand 4,4’-Ph2PC6H4-C6H4PPh2 leads to covalent linking of the gold clusters via intermolecular -C6H4-N=PPh2C6H4-C6H4Ph2P=N-C6H4- bridges to form networks of clusters.

Summary for Lay Audience

Gold nanoclusters are atomically precise nanomaterials that have been widely used for their unique optical and chemical properties. They comprise of an internal metallic framework surrounded by an external layer of protecting ligands. However, because most gold clusters reported so far bear ligands that have no reactive functional group, the use of the clusters for application has been somewhat limited because of the need to synthesize cluster with ligands that has reactive functional groups. Recently, gold nanoclusters with a ligand bearing a reactive handle, known as the azide, has been developed. The advantage of this newly developed gold nanocluster is that the surface ligands can now undergo reactions with the azide, which undergoes rapid, efficient chemistry with appropriate reaction partners through a “click reaction”. The azide nanocluster thus serves as a template material to access a wide variety of new nanocluster to change the properties of the nanocluster and tune their properties for potential applications. This thesis includes one of the many click type reactions that can occur on the azide group of the ligands on the cluster, also known as the Staudinger reaction. The reaction will form networks of the nanometer sized clusters.

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