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 <b>V</b>_<b>6</b><b>-vIM</b>, 1-vIM = 1-vinylimidazole] and {(mIM)₈(CH₃O)₈V^IV₈V^V₄O₂₂}·2.5H₂O [abbr <b>V</b>_<b>12</b><b>-mIM</b>, 1-mIM = 1-methylimidazole], were synthesized under solvothermal conditions. The principal building unit of <b>V</b>_<b>12</b><b>-mIM</b> 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, <b>V</b>_<b>12</b><b>-mIM</b> was used for the oxidation of sulfide. <b>V</b>_<b>12</b><b>-mIM</b> was an efficient heterogeneous catalyst that could completely convert most sulfides with H₂O₂ as the oxidant within 40 min at 30 °C. Importantly, <b>V</b>_<b>12</b><b>-mIM</b> maintained good structural stability and catalytic activity after five cycles.