Self-Assembled Monolayers of CH3COS- Terminated Surfactant-Encapsulated Polyoxometalate Complexes

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• 作者：Hang Sun ; Weifeng Bu ; Yancai Li ; Haolong Li ; Lixin Wu ; Changqing Sun ; Bin Dong ; Ruifen Dou ; Lifeng Chi ; Andreas Schaefer
• 刊名：Langmuir
• 出版年：2008
• 出版时间：May 6, 2008
• 年：2008
• 卷：24
• 期：9
• 页码：4693 - 4699
• 全文大小：475K
• 年卷期：v.24,no.9(May 6, 2008)
• ISSN：1520-5827

文摘

Self-assembled monolayers (SAMs) on gold surfaces based on three kinds of acetylthio-surfactant-encapsulatedpolyoxometalate clusters (thio-SECs) terminated with multiple CH₃COS- groups, (NC₂₆H₅₅S(CO)CH₃)₆H₂[Co(H₂O)CoW₁₁O₃₉], (NC₂₆H₅₅S(CO)CH₃)₁₃H₃[Co₄(H₂O)₂(P₂W₁₅O₅₆)₂], and (NC₂₆H₅₅S(CO)CH₃)₁₃[Fe₄(H₂O)₂(P₂W₁₅O₅₆)₂]Br,have been prepared, which is representative of a general methodology to fabricate polyoxometalate-based SAMs.Thio-SECs self-assembled into monolayers on gold surfaces through the hydrolysis of CH₃COS- groups and thesubsequent formation of S-Au bonds, which was confirmed by grazing angle infrared spectroscopy, X-ray photoelectronspectroscopy, and ellipsometric and scanning tunneling microscopy (STM) measurements. Furthermore, the SAMsof the thio-SECs possess closely packed structures, and the local short-range order is clearly observed in the magnifiedSTM image. We have also investigated the electrochemical behavior of SAMs of thio-SECs by cyclic voltammetryin detail, and the redox potential of the original polyoxometalates has been well retained. The electrochemical signalsof the SAMs are very weak because of the small moiety of thio-SECs that are electrochemically accessible in thecyclic voltammetry experiments. The polyoxometalate-modified electrodes that we prepared are not only highlyordered in the local short range but also stable in electrochemical cycling because of the multiple S-Au bonds ofthio-SECs on the gold substrates that aid in the construction of functional materials such as electrochemical andelectrocatalytic devices.