Electronic properties of PVA‑PVAm ligands dictate mechanistic pathways in Au/AC‑catalyzed HMF oxidation

The development of efficient catalysts for the production of 2,5-furandicarboxylic acid (FDCA) from 5-(hydroxymethyl)furfural (HMF) is crucial to reduce the environmental footprint and achieve economically favorable conditions for its use in polyethylene 2,5-furandicarboxylate (PEF) synthesis. In this work, we demonstrated the possibility of tuning the electronic properties of Au nanoparticle-based catalysts via polymeric stabilizers to control HMF oxidation mechanism and product distribution. Polyvinyl alcohol (PVA), polyvinyl amine (PVAm), and poly(N-vinyl amine-co-vinyl alcohol) (PVA-co-PVAm) copolymers were synthesized with various compositions to evaluate the effect of functional groups on ligand–metal interactions. The presence of amino groups increases electron donation to Au, as confirmed by DFT calculations of monomer adsorption on cluster models of amorphous Au NPs. DFT investigations, NMR relaxation studies, and catalytic studies further revealed that increasing electron-donor groups modifies the reaction mechanism and enhances selectivity, particularly through manipulating the adsorption of reaction intermediates. These results provide mechanistic insights into the role of stabilizers and the active phase in directing specific reaction pathways. This understanding enables the rational design of polymeric ligands to enhance catalyst performance for aerobic oxidation of biomass-derived molecules in water under mild conditions, underscoring the role of stabilizer engineering in achieving selective and sustainable catalytic processes.