Nitroxide-functionalized Atomically Precise Ag20 Nanoclusters for Electrocatalytic Oxidations

Ali Roberto Ruiz Hernandez, Western University

Abstract

Preparing atomically precise silver nanoclusters (Ag NC) modified with functional ligands capable of post-synthetic chemistry for use in potential applications like sensing, catalysis, and electrochemical processes remains a challenge. In this thesis, the synthesis of a novel stable free radical (TEMPO) functionalized Ag₂₀ NC and some derivatives are presented, and their molecular structures are characterized by single crystal X-ray diffraction (SCXRD). The clusters were also characterized by multinuclear-NMR, IR, UV-vis, EPR and XPS spectroscopies, asserting the stability and novelty of free radical moieties in Ag NCs. The optical properties of the TEMPO-modified Ag₂₀ NC, important for optical sensing applications, were probed using photoluminescence (PL) and electrochemiluminescence (ECL) spectroscopies. The electrochemical properties and catalytic behaviour of Ag₂₀TEMPO₆ NC were studied, exhibiting reversible redox behaviour with diffusion-controlled kinetics and displaying proof of concept of electrocatalytic activity in the oxidation of alcohols. Other post-synthetic reactions, like the regeneration of the nitroxide radical from a methoxyamine Ag₂₀ NC derivative (Ag₂₀MeTEMPO₈ NC) with a nucleophile, were also investigated. The results contribute to a deeper understanding of the properties of atomically precise Ag NCs and expand the scope of post-synthetic cluster surface chemistry of functionalized Ag NCs.