Proton-Assisted Reduction of CO2 by Cobalt Aminopyridine Macrocycles

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• 作者：Alon Chapovetsky ; Thomas H. Do ; Ralf Haiges ; Michael K. Takase ; Smaranda C. Marinescu
• 刊名：Journal of the American Chemical Society
• 出版年：2016
• 出版时间：May 11, 2016
• 年：2016
• 卷：138
• 期：18
• 页码：5765-5768
• 全文大小：326K
• 年卷期：0
• ISSN：1520-5126

文摘

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 azacalix[4](2,6)pyridine 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.