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用循环伏安法在二氯甲烷、乙腈、丙酮、甲醇、二甲基甲酰胺和二甲亚砜等有机溶剂体系中研究了硝酸铕与不周冠醚配合物的电还原反应.溶剂介质和冠醚结构对Eu~(3+)冠醚配合物氧化还原反应有显著影响.在弱配位溶剂中冠醚的配位作用稳定了Eu~(2+),使Eu~(3+)的还原电位向阳极方向移动200mV左右.由于强配位溶剂的作用,体系还原反应可能成为EC机制.同一冠醚配合物在不同弱配位溶剂中k_s差别不大,但在强配位溶剂中其k_ 明显下降.同时,电还原反应的E_(1/2)越负,K_s也越小.
The reduction reaction of europium nitrate with non-cyclic crown ether was studied by cyclic voltammetry in dichloromethane, acetonitrile, acetone, methanol, dimethylformamide and dimethylsulfoxide. The solvent medium and crown ether The structure of Eu ~ (3 +) crown ether complex redox reaction has a significant effect.In the weak coordination solvent, the coordination of the crown ether stabilizes the Eu ~ (2+), Eu ~ (3 +) reduction potential Which is about 200mV toward the anode.As a result of the strong coordination solvent, the system reduction reaction may become an EC mechanism.Under the same weakly complexing solvent, the same crown ether complex has little difference in k_s, but k_ in the strong coordination solvent At the same time, the more negative E_ (1/2) of the electro-reduction reaction, the smaller K_s.