Electrochemical and Spectroelectrochemical Insights Into Benzenediol and Nitrobenzenediol Toward Magnetite Nanoparticle Functionalization

ABSTRACT Magnetic nanoparticles (MNPs) were functionalized with 1,2‐benzenediol (BEN) and 4‐nitrobenzene‐1,2‐diol (NC) to assess how additional substituents affect surface binding and functionalization efficiency beyond hydroxyl anchoring. Successful modification was confirmed by FT‐IR, XRD, TEM, TGA, and XPS. Thermogravimetric analysis revealed that BEN achieves a markedly higher degree of functionalization, with ~47% greater organic content than NC, indicating stronger interaction with the magnetite surface. XPS showed that, in NC‐functionalized MNPs, nitro groups participate in secondary interactions with surface Fe sites, altering the local electronic environment. In situ UV–Vis spectroelectrochemistry evidenced the formation of o ‐benzoquinone and semiquinone intermediates and demonstrated that the electron‐withdrawing NO 2 group modifies the redox pathway, promoting competing reactions that limit effective ligand anchoring. Density functional theory calculations supported these findings, showing preferential Fe–catechol interactions and secondary nitro coordination. Overall, substituent‐driven electronic effects critically govern functionalization efficiency. These insights clarify the interactions between ligands and nanoparticles while aiding in the strategic design of functionalized magnetic nanomaterials.