Colloidal tectonics for tandem synergistic Pickering interfacial catalysis: oxidative cleavage of cyclohexene oxide into adipic acid

Abstract

Supramolecular preorganization and interfacial recognition can provide useful architectures for colloidal building. To this aim, a novel approach, based on colloidal tectonics involving two surface-active particles containing both recognition and catalytic sites, has been developed for controlling the formation and the properties of Pickering emulsions. This was illustrated by the combination of dodecyltrimethylammonium phosphotungstate nanoparticles, [C₁₂]₃[PW₁₂O₄₀], and silica particles functionalized with alkyl and sulfonic acid groups, [C_n/SO₃H]@SiO₂. The interfacial self-assembly occurs by the penetration of the alkyl chains of [C_n/SO₃H]@SiO₂ into the [C₁₂]₃[PW₁₂O₄₀] supramolecular porous structure constituted of polar and apolar regions. The emulsions were used as a non-nitric acid route for adipic acid synthesis from the one-pot oxidative cleavage of cyclohexene oxide with aqueous H₂O₂. The catalytic performance was significantly boosted due to the synergistic interactions between the particles.