Two Imidazole-Functionalized Mixed-Valence Oxidovanadium Clusters for Catalytic Oxidation of Sulfides

The design of efficient and stable catalysts for sulfide oxidation is crucial for mitigating acid rain. In this work, two novel imidazole-functionalized mixed-valence oxidovanadium clusters, {(vIM)₈V^IV₂V^V₄O₁₄}·H₂O [abbr V₆-vIM, 1-vIM = 1-vinylimidazole] and {(mIM)₈(CH₃O)₈V^IV₈V^V₄O₂₂}·2.5H₂O [abbr V₁₂-mIM, 1-mIM = 1-methylimidazole], were synthesized under solvothermal conditions. The principal building unit of V₁₂-mIM exhibits a rare funnel shape in dodecanuclear oxidovanadium clusters. Considering that the presence of V^IV/V^V can potentially enhance electron transfer and thereby accelerate catalytic reactions, V₁₂-mIM was used for the oxidation of sulfide. V₁₂-mIM was an efficient heterogeneous catalyst that could completely convert most sulfides with H₂O₂ as the oxidant within 40 min at 30 °C. Importantly, V₁₂-mIM maintained good structural stability and catalytic activity after five cycles.