2007年12月
Enhancements in the electron-transfer kinetics of uranium-based redox couples induced by tetraketone ligands with potential chelate effect
JOURNAL OF PHYSICAL CHEMISTRY C
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- 巻
- 111
- 号
- 50
- 開始ページ
- 18812
- 終了ページ
- 18820
- 記述言語
- 英語
- 掲載種別
- 研究論文(学術雑誌)
- DOI
- 10.1021/jp077243z
- 出版者・発行元
- AMER CHEMICAL SOC
Acetylacetone shows dissociative electron transfer when it is complexed with metal ions. In an effort to improve the kinetics of electron transfer of uranium-based complexes for application to a redox-flow battery, improvement by dimerization of acetylacetone into tetraketones with potential chelate effect is examined and discussed quantitatively. For the monomer acetylacetone, electron transfer of uranium complexes reveals an ECE mechanism and an inner-sphere reaction on the electrode surface. By using tetraketones, 8-oxo-2,4,12,14-tetraoxapentadecane and m-bis(2,4-dioxo-l-pentyl)benzene, the electron transfer of tetraketones with U(VI)/U(V) and U(IV)/U(III) shows rapid kinetics based on the E mechanism. In clear contrast to U(acac)4, the electrochemically reduced species of the U(IV) complex with tetraketone is stable during potential cycling. These results are also supported by NMR of tetraketones with U(VI) and U(IV); each acetylacetone site to uranium atom is stable at -40 similar to +40 degrees C. The results demonstrate a remarkable enhancement of the stability of the reduced form of the metal center and thereby an improvement of the redox kinetics by the chelate effect. The tetraketones are eminently suitable for use in the active materials of a high-efficiency redox-flow battery.
- リンク情報
- ID情報
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- DOI : 10.1021/jp077243z
- ISSN : 1932-7447
- Web of Science ID : WOS:000251615500050