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化学学报
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化学学报 ›› 2008, Vol. 66 ›› Issue (8): 835-840.    下一篇

研究论文

Cr(III)-取代磷钨杂多配合物对4-甲基吡啶的电催化氧化作用

王崇太*,1,2，华英杰2，李高仁1，童叶翔1，李玉光*,1   

  1. (1中山大学化学化工学院 光电功能复合材料研究所 广州 510275)
    (2海南师范大学化学系 海口 571158)
  • 投稿日期:2007-09-24 修回日期:2007-11-10 发布日期:2008-04-28
  • 通讯作者: 王崇太

Electrocatalytic Oxidation of 4-Methylpyridine by Cr(III)-Substituted Phosphorus Heteropolytungstate

WANG Chong-Tai*,1,2 HUA Ying-Jie2 LI Gao-Ren1 TONG Ye-Xiang1 LI Yu-Guang*,1   

  1. (1 Institute of Optoelectronic and Functional Composite Materials, School of Chemistry and Chemical Engineering, Zhongshan University, Guangzhou 510275)
    (2 Department of Chemistry, Hainan Normal University, Haikou 571158)
  • Received:2007-09-24 Revised:2007-11-10 Published:2008-04-28
  • Contact: WANG Chong-Tai

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利用Cr(III)-取代磷钨杂多配合物PW11O39CrIII(H2O)4－的内球电子转移特性, 通过与反应活性中心CrIII(H2O)第六配位水分子的交换反应, 将4-甲基吡啶分子络合修饰到该活性中心上进行阳极催化氧化. 可见吸收光谱证实4-甲基吡啶和CrIII(H2O)中心进行配体交换反应生成PW11O39CrIII(NC6H7)4－; 而循环伏安和恒电位电解实验结果表明, 修饰在Cr(III)活性中心上的4-甲基吡啶分子每一步都经历2电子氧化, 依次生成吡啶-4-甲醇, 吡啶-4-甲醛和吡啶-4-甲酸. 由此提出了一个关于这类反应的分子内电催化模板机制, 为过渡金属取代杂多配合物作为间接氧化电催化剂的应用开辟了一条新途径.

关键词: 铬取代杂多配合物, 电催化氧化, 4-甲基吡啶, 循环伏安

On the basis of the characters that PW11O39CrIII(H2O)4－ is oxidized or reduced in the inner-sphere electron transfer manner and that the sixth coordinate water bound to Cr(III) center is readily replaced by other ligand, the electrocatalytic oxidation of 4-methylpyridine by PW11O39CrIII(H2O)4－ was investigated. Vis spectrum confirmed the existence of PW11O39CrIII(NC6H7)4－ due to a ligand exchange reaction between 4-methylpyridine and H2O in PW11O39CrIII(H2O)4－. Cyclic voltammetric and potential-controlled electrolyte experiments indicated that the molecule of 4-methylpyridine modified onto the Cr(III) active center was oxidized via a two electron transfer to form pyridine-4-methanol, pyridine-4-carboxaldehyde and 4-picolinic acid in turn. A novel electrocatalytic mechanism involving in intramolecular electron transfer was proposed, and thus a possible application to the electrocatalytic oxidation of substrate by transition metal-substituted heteropolyanions was provided according to this model.

Key words: Cr(III)-substituted heteropolytungstate, electrocatalytic oxidation, 4-methylpyridine, cyclic voltammetry