Thesis Format
Integrated Article
Degree
Doctor of Philosophy
Program
Chemistry
Supervisor
Workentin, Mark S.
2nd Supervisor
Corrigan, John F.
Affiliation
University of Waterloo
Co-Supervisor
Abstract
Nanomaterials like nanoparticles or nanoclusters are finding more interest in applications of material science, medicine and catalysis. The field of nanocluster research continues to provide new structures of differing stoichiometries and properties. New cluster frameworks can be targeted by altering the synthetic conditions or the stabilizing surface ligands. The direct synthesis of cluster species and the ligand exchange reactions on the clusters bring problems with them, that can lead to changes in composition as well as the decomposition of the desired cluster. Much less focus has been on modifying cluster surfaces post-synthesis while maintaining the cluster core. Our group’s recent efforts have been directed at preparing metal nanoclusters with reactive surface substrates to serve as templates and exploring the cluster-surface reactivity to alter their function post-synthesis while maintaining the core structure.
This work targets atomically precise CO32- templated Ag20 nanoclusters (NCs) with 8 and 6 surface moieties containing reactive surface functionalities based on the previous reported [CO3@Ag20(StBu)10((NO3)8(DMF)4] by Gao et al.. To synthesize these Ag20NC`s the procedure for the preparation of [CO3@Ag20(StBu)10((NO3)8(DMF)4] was modified with the addition of desired functional benzoate derivatives (O2CC6H4-R) that substitute the surface nitrate ions. In this thesis, the family of cluster surface-reactive [CO3@Ag20(StBu)10((O2CC6H4-R)8-x(NO3)x(DMF)4] was elaborated to include photochemically reactive cluster-surface moieties and here is described the synthesis, photochemical isomerization of aryl-azo-groups, trifluoromethyl-aryldiazirine moieties for the generation of reactive carbene on the cluster surface of the Ag20-moiety, and perfluorinated phenylazide capable of subsequent cluster surface (CS) functionalization via click reactions.
The surface aryl-azo-groups were used to investigate the photostability of the Ag20 core as well as the isomerization of the azo bond between its Z and E isomers. The trifluoromethyl-aryldiazirine Ag20-NC provides a photochemical route to cluster surface reactive carbenes that insert into X-H bonds and add to alkenes to deliver functionality for applications for catalysis and medicine. The perfluorinated phenylazide surface functionality was used to show with model phosphines the possibility for surface click reaction via Staudinger and Staudinger-Bertozzi ligations to decorate the cluster surface under mild conditions for application in medicine or catalysis.
Summary for Lay Audience
Silver has been known as a valuable precious metal and saw use over aeons in human history. The longest use of silver is the form of jewelry and ornamentation or as currency and modern investment and storage of capital. Silver was also essential to the founding of the exposure-based photography where silver-based solutions gave the black and white pictures their contrast due to its photosensitivity. But silver is also used in medicine since silver containing drugs have shown in anti-cancer effects. As anti-bacterial, anti-fungal drugs silver salts were used in emergency and first aid kits.
Recently silver particles in the nanometer scale (quantum dots) became an area of research interest because of their unique light emitting and semiconducting properties, making them potential candidates for replacing more concerning semiconductors made of harmful and toxic heavy metal-based quantum dots. Silver based semiconductors quantum dots have the chance to be useful for medical applications and solar power applications. These are promising nontoxic and biocompatible materials and are easier to recycle. However, quantum dots are not single identical molecules, more a mix of substances of varying but similar sizes.
Precise changes on diverse particles are quite difficult and can and in various properties and structures of these substances. Without high regulations to use these substances are hard to overcome for a use in medicinal applications and predict their behavior. From this reason, the desire to produce and investigate finely control the well-defined materials became popular. Silver clusters and their atomically precise nature fulfilled at the same time behaviour of semiconductors and ease of producing and characterising of molecular silver compounds.
Silver nanoclusters (AgNC’s) are smaller than nanoparticle but have a specific chemical formula and so a silver nanocluster refers to a single atomically defined formula. Any chemical changes on the nanocluster are describable and traceable. A change on the surface of these here investigated clusters can be brought into relationships between structure and the observed properties. Also an easy and mild way to modify the AgNC`s was established so that the same nanocluster are quick modified for many different properties for example as part of a screen, as a diagnostic in medicine as well as a potential drug for divers medical conditions.
Recommended Citation
Vogeler, Nils Hermann, "Exploring the Scope of cluster-surface reactive Ag-Nanocluster" (2025). Electronic Thesis and Dissertation Repository. 10689.
https://ir.lib.uwo.ca/etd/10689
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.
