摘要
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.
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（NC6HT）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, pyri- dine-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.
出处
《化学学报》
SCIE
CAS
CSCD
北大核心
2008年第8期835-840,共6页
Acta Chimica Sinica
基金
海南省教育厅高等学校科研(No.Hjkj200617)资助项目
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
Cr（Ⅲ）-substituted heteropolytungstate
electrocatalytic oxidation
4-methylpyridine
cyclic voltammetry
