Department of Chemistry, University of Southern California , Los Angeles, California 90089, United States.
Beckman Institute, California Institute of Technology , Pasadena, California 91125, United States.
J Am Chem Soc. 2016 May 11;138(18):5765-8. doi: 10.1021/jacs.6b01980. Epub 2016 Apr 27.
We report here the efficient reduction of CO2 to CO by cobalt aminopyridine macrocycles. The effect of the pendant amines on catalysis was investigated. Several cobalt complexes based on the azacalix4pyridine framework with different substitutions on the pendant amine groups have been synthesized (R = H (1), Me (2), and allyl (3)), and their electrocatalytic properties were explored. Under an atmosphere of CO2 and in the presence of weak Brønsted acids, large catalytic currents are observed for 1, corresponding to the reduction of CO2 to CO with excellent Faradaic efficiency (98 ± 2%). In comparison, complexes 2 and 3 generate CO with TONs at least 300 times lower than 1, suggesting that the presence of the pendant NH moiety of the secondary amine is crucial for catalysis. Moreover, the presence of NH groups leads to a positive shift in the reduction potential of the Co(I/0) couple, therefore decreasing the overpotential for CO2 reduction.
我们在这里报告了钴氨基吡啶大环化合物将二氧化碳高效还原为一氧化碳。研究了侧胺对催化的影响。已经合成了几种基于氮杂杯4吡啶骨架的钴配合物，这些配合物在侧胺基团上具有不同的取代基（R = H(1)、Me(2)和烯丙基(3))，并探索了它们的电催化性能。在 CO2 气氛下和弱布朗斯台德酸的存在下，1 表现出大的催化电流，对应于 CO2 还原为 CO 的极好的法拉第效率（98±2%）。相比之下，配合物 2 和 3 生成 CO 的 TON 至少比 1 低 300 倍，这表明仲胺的侧 NH 部分的存在对于催化至关重要。此外，NH 基团的存在导致 Co(I/0) 配合物的还原电位正向移动，从而降低 CO2 还原的过电位。
