Behavior of Ionic Liquids Around Charged Metal Complexes: Investigation of Homogeneous Electron Transfer Reactions Between Metal Complexes in Ionic Liquids
Behavior of Ionic Liquids Around Charged Metal Complexes: Investigation of Homogeneous Electron Transfer Reactions Between Metal Complexes in Ionic Liquids
复制标题
带电金属配合物周围离子液体的行为：离子液体中金属配合物之间均相电子转移反应的研究
DOI：
10.1007/s10953-018-0772-6
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发表时间：
2018
影响因子：
1.2
通讯作者：
Hideo D. Takagi
中科院分区：
文献类型：
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作者：
Takuya Mabe;Fumiaki Doseki;Takeyoshi Yagyu;Koji Ishihara;Masahiko Inamo;Hideo D. Takagi
研究了[Zn(TPP)]* （TPP = 5,10,15,20-四苯基卟啉）和[Co(sep)]3+（sep = sepulchrate = 1,3,6,8,10,13,16,19-八氮杂环[6.6.6]二十烷）在3种离子液体(ILs， 1-R-3-甲基咪唑-二（三氟甲基磺酰基）亚胺（R =丁基、戊基和己基）和乙腈中的光激发三重态的二级电子转移反应。电化学和动力学测量结果表明，在带电金属配合物附近和电极处，虽然游离的阴离子和阳离子成分似乎在金属配合物周围成对存在。在298 K时，电子转移反应的二阶速率常数分别为1.88 × 109、3.65 × 107、2.63 × 107和2.01 × 107kg·mol−1·s−1，在乙腈和丁基、戊基和己基苯环中，对扩散的贡献进行了修正。在乙腈和ILs中观察到的对数二阶速率常数随每种溶剂的对数粘度曲线的平均斜率为- 0.84。然而，当仅使用三个il的数据时，同一图的斜率要陡峭得多（−4.1）。根据Latner-Levin交联关系和Marcus理论对实验结果进行了详细分析，得出了溶剂性质如极化/带电过渡态周围的介电常数和折射率与块体ILs不同的结论：当使用块体ILs的介电常数和折射率时，观察到的自交换速率常数不表现出Pekar因子依赖。
The second-order electron transfer reaction between the photo-excited triplet state of [Zn(TPP)]* (TPP = 5,10,15,20-tetraphenylporphyrin) and [Co(sep)]3+(sep = sepulchrate = 1,3,6,8,10,13,16,19-octaazabicyclo[6.6.6]eicosane) was investigated in three ionic liquids (ILs, 1-R-3-methylimidazolium bis(trifluoromethylsulfonyl)imide with R = butyl, pentyl, and hexyl) and in acetonitrile. Results of electrochemical and kinetic measurements indicated that ILs dissociate in the vicinity of charged metal complexes and at electrodes, although the dissociated anionic and cationic components of the ILs seem to exist as pairs around the metal complexes. Second-order rate constants for the electron transfer reaction are 1.88 × 109, 3.65 × 107, 2.63 × 107, and 2.01 × 107kg·mol−1·s−1in acetonitrile and in the butyl, pentyl and hexyl ILs, respectively, at 298 K, after correction of the contribution of diffusion. The average slope of the plot of the logarithmic second-order rate constants observed in acetonitrile and ILs against the logarithmic viscosity of each solvent was − 0.84. However, the slope of the same plot was much steeper (− 4.1) when data for only the three ILs were used. Detailed analyses of the experimental results on the basis of the Latner–Levin cross relation and the Marcus theory lead to the conclusion that the solvent properties such as the dielectric constant and refractive index around the polarized/charged transition states are different from those for the bulk ILs: observed self-exchange rate constants did not exhibit the Pekar factor dependence when dielectric constants and refractive indices for bulk ILs are used.