Electron Transfer to a Phosphomolybdate Monolayer on Glassy Carbon: Ambivalent Effect of Protonation

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• 作者：Corentin Rinfray ; Vitor Brasiliense ; Guillaume Izzet ; Florence Volatron ; Sandra Alves ; Catherine Combellas ; Frédéric Kanoufi ; Anna Proust
• 刊名：Inorganic Chemistry
• 出版年：2016
• 出版时间：July 18, 2016
• 年：2016
• 卷：55
• 期：14
• 页码：6929-6937
• 全文大小：448K
• 年卷期：0
• ISSN：1520-510X

文摘

The polyoxomolybdate hybrid TBA₃[PMo₁₁O₃₉{Sn(C₆H₄)C≡C(C₆H₄)N₂}] K^Mo_Sn[N₂⁺] was prepared through Sonogashira-type coupling between TBA₄[PMo₁₁O₃₉{Sn(C₆H₄)I}] K^Mo_Sn[I] and an excess of 3,3-diethyl-1-(4-ethynylphenyl)triaz-1-ene bearing a protected diazonium function, followed by its deprotection by the addition of trifluoroacetic acid (TFA). This enlarges the family of organic–inorganic polyoxomolybdate-based hybrids, which has been far less investigated than their related polyoxotungstates. The diazonium function allows for the electrochemical grafting on glassy carbon, and the K^Mo_Sn-modified electrode was further probed by cyclic voltammetry. The PMo₁₁Sn core was found to be highly sensitive to protonation, and five bielectronic proton-coupled electron transfer processes were detected in the presence of an excess of TFA, thus corresponding to the injection of up to 10 electrons in the potential range between 0.15 and −0.45 V/SCE. The gain observed in the thermodynamic potentials is however detrimental to the apparent kinetics of the electron transfer, which drops from 500 s^–1 in the absence of acid to 12 s^–1 in the presence of an excess of TFA.