MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry, Sun Yat-Sen University , Guangzhou 510275, China.
J Am Chem Soc. 2018 Jan 10;140(1):38-41. doi: 10.1021/jacs.7b10107. Epub 2017 Dec 28.
Converting CO into fuels via photochemical reactions relies on highly efficient and selective catalysts. We demonstrate that the catalytic active metal center can cooperate with neighboring hydroxide ligands to boost the photocatalytic CO reduction. Six cobalt-based metal-organic frameworks (MOFs) with different coordination environments are studied at the same reaction condition (photosensitizer, electron donor, water/organic mixed solvent, and visible light). In pure CO at 1.0 atm, the MOFs bearing μ-OH ligands neighboring the open Co centers showed CO selectivities and turnover frequencies (TOFs) up to 98.2% and 0.059 s, respectively. More importantly, their TOFs reduced only ca. 20% when the CO partial pressure was reduced to 0.1 atm, while other MOFs reduced by at least 90%. Periodic density functional theory calculations and isotope tracing experiments showed that the μ-OH ligands serve not only as strong hydrogen-bonding donors to stabilize the initial Co-CO adduct but also local proton sources to facilitate the C-O bond breaking.
通过光化学反应将 CO 转化为燃料依赖于高效和选择性的催化剂。我们证明，催化活性金属中心可以与相邻的氢氧根配体协同作用，从而促进光催化 CO 还原。在相同的反应条件（光敏剂、电子供体、水/有机混合溶剂和可见光）下，研究了具有不同配位环境的六种钴基金属-有机骨架（MOF）。在纯 CO（1.0 atm）中，带有紧邻开放 Co 中心的 μ-OH 配体的 MOF 表现出高达 98.2%的 CO 选择性和 0.059 s 的周转频率（TOF）。更重要的是，当 CO 分压降低至 0.1 atm 时，它们的 TOF 仅降低了约 20%，而其他 MOF 的降低至少为 90%。周期性密度泛函理论计算和同位素示踪实验表明，μ-OH 配体不仅作为稳定初始 Co-CO 加合物的强氢键供体，而且作为局部质子源促进 C-O 键断裂。
