Enhancing efficiency of solvent-free oxidation of aromatic alcohols with atmospheric oxygen by POSS-based cationic polymer backbone paired heteropolyanions

Oxidation is among the most crucial reactions for the production of chemicals and many noble metals are the efficient active centers. The catalysts derived from non-noble metal species are preferred thanks the low cost and earth abundance but suffered from inferior efficiency to noble metal ones. Herein, we demonstrated an unusual effective non-noble metal heterogeneous catalyst for the solvent-free synthesis of aromatic aldehydes from selective O₂-mediated oxidation of alcoholic compounds. The target catalyst was prepared by the copolymerization of divinylimidazole dibromide and polyhedral oligomeric silsesquioxane, followed by loading phosphomolybdenum anions via ion exchange. The catalyst gave high yields of up to 93% towards aldehydes, stable reusability, and extendable substrate scope in transforming aromatic alcohols without any solvent. The high performance comes from the abundant low valence Mo species derived from the strong cation-anion interaction, which promoted the O₂ activation to give superoxides (•O₂⁻) as the reactive oxygen species.