A novel polyoxovanadate-based metal–organic framework (POV-MOF), [Ni(bix)₂]{V₄O₁₁} (V-Ni-MOF, bix = 1,4-bis(imidazol-1-ylmethyl)benzene), was successfully synthesized and structurally characterized. Single crystal X-ray diffraction analysis shows that the {V₄} clusters in V-Ni-MOF are composed of four VO₄ tetrahedra and further connected into a tandem-like chain. The unique vanadium chains with high-density coordinatively unsaturated vanadium centers in V-Ni-MOF can efficiently catalyze the oxidation of sulfides, where sulfides were completely converted to sulfones with the mild oxidant hydrogen peroxide within 1 hour at 40 °C. To our knowledge, most POV-MOFs could efficiently catalyze the oxidation of sulfides only when a stronger oxidant such as tert-butyl hydroperoxide was used. We attempted to utilize density functional theory (DFT) calculations to explore the reason for the high activity of V-Ni-MOF under mild hydrogen peroxide. DFT calculations indicated that the tandem-like vanadium cluster chain has a lower lowest unoccupied molecular orbital (LUMO) energy level compared to a discrete vanadium cluster, which matches better with the highest occupied molecular orbital (HOMO) energy level of hydrogen peroxide to generate active peroxo-POV species. In addition, as a stable heterogeneous catalyst, V-Ni-MOF sustainably maintains an excellent catalytic activity after multiple cycles.

中文翻译：

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多氧钒酸盐基金属-有机骨架中串联状钒簇链可有效催化氧化硫化物

一种新型多氧钒酸盐基金属有机骨架 (POV-MOF)，[Ni(bix) ₂ ]{V ₄ O ₁₁ } ( V-Ni-MOF , bix = 1,4-双(咪唑-1-基甲基)苯)，被成功合成和结构表征。单晶X射线衍射分析表明，V-Ni-MOF中的{V ₄ }簇由四个VO ₄四面体组成，并进一步连接成串联状链。V-Ni-MOF中具有高密度配位不饱和钒中心的独特钒链可以有效地催化硫化物的氧化，在 40°C 下，硫化物在 1 小时内用温和的氧化剂过氧化氢完全转化为砜。据我们所知，大多数 POV-MOF 只有在使用更强的氧化剂（如叔丁基过氧化氢）时才能有效地催化硫化物的氧化。我们试图利用密度泛函理论 (DFT) 计算来探索V-Ni-MOF高活性的原因在温和的过氧化氢下。DFT 计算表明，与离散的钒簇相比，串联状钒簇链具有较低的最低未占分子轨道 (LUMO) 能级，这与过氧化氢的最高占据分子轨道 (HOMO) 能级更好地匹配以产生活性过氧 POV 物种。此外，作为一种稳定的多相催化剂，V-Ni-MOF在多次循环后可持续保持优异的催化活性。