Electronic Thesis and Dissertation Repository

Degree

Doctor of Philosophy

Program

Chemistry

Supervisor

Mark S. Workentin

2nd Supervisor

Zhifeng Ding

Joint Supervisor

Abstract

A series of monodispersed AuNCs including Au144(SR)60, Au38(SR)24 and Au25(SR)18z (z =1-, 0 and 1+, SR=2-phenylethanethiol) were prepared. All these nanoclusters showed molecule-like optical and electrochemical properties. These two features are essential for an electrogenerated chemiluminescence or electrochemiluminescence (ECL) study. The Au144(SR)60 showed a small HOMO-LUMO gap determined by electrochemistry. No ECL light was seen in the annihilation process, while NIR ECL was observed with tri-n- propylamine (TPrA) (Chapter 2). ECL was highly efficient in the Au38(SR)24/TPrA co- reactant system. This nanocluster also showed ECL emission with benzoyl peroxide (BPO), while no ECL was detected in the annihilation route (Chapter 3). The ECL of Au25(SR)18z (z =1-, 0 and 1+) were discovered to emit NIR ECL light in the presence of either TPrA or BPO co-reactant. The Au25(SR)18+/ TPrA system revealed the strongest ECL emission among the three Au25 oxidation states (Chapter 4). The thermodynamic (Latimer-type diagram) and the kinetic origins of Au25(SR)180 ECL were explored in the presence of TPrA (Chapter 5). And lastly, the NIR ECL of Au25(SR)18− nanoclusters was mechanistically investigated in the presence of both TPrA and BPO with NIR emissions in both systems (Chapter 6).

In each case a multiple ECL emissions were observed. The ECL peak wavelength and ECL intensity can be tuned by means of both the co-reactant concentration and applied electrode potential. It is worth noting that the Au38(SR)24 showed the strongest ECL efficiency among all the clusters studied, and the Au25(SR)18z clusters possessed a rich photoelectrochemistry leading to highly efficient ECL.

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