Elucidating the oxidation mechanism of scopolamine derivatives via electrochemistry, UV–Vis, and NMR

Selective field detection of scopolamine derivatives is challenged by ambiguous mechanistic interpretations of the redox pathway. Here, the oxidation behavior of scopolamine hydrobromide (SHBr) and scopolamine N-butyl bromide (SBBr) at pH 2 on unmodified glassy carbon and platinum electrodes was studied using voltammetry, in situ UV–Vis spectroelectrochemistry, and multinuclear NMR. All faradaic signals arise from Br−/Br<inf>2</inf>oxidation, with SHBr exhibiting a characteristic secondary peak possibly attributable to –OH oxidation at 1.46 V vs. SCE. Identical λ<inf>max</inf>(∼385 nm) in UV–Vis spectroscopy and unchanged NMR resonances confirm the absence of organic-site oxidation, revealing only acid-catalyzed hydrolysis. We propose a unified proton-electron mechanism in which protonated ammonium moieties remain electrochemically inert under acidic conditions, enabling selective bromide detection. As a mechanistic proof-of-concept, these findings demonstrate that the oxidation mechanism of brominated scopolamine derivatives can be elucidated using simple, unmodified glassy carbon electrodes. This mechanistic baseline provides a foundation for a future rational design of electrode interfaces tailored to bromide-based scopolamine derivative detection. © 2025 Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.