Nitroxide-functionalized Atomically Precise Ag20 Nanoclusters for Electrocatalytic Oxidations

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.