Enhancements in the electron-transfer kinetics of uranium-based redox couples induced by tetraketone ligands with potential chelate effect

Tomoo Yamamura, Kenji Shirasaki, Hironori Sato, Yoshiyuki Nakamura, Hiroshi Tomiyasu, Isamu Satoh, Yoshinobu Shiokawa

研究成果: Article査読

12 被引用数 (Scopus)

抄録

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-1-pentyl)benzene, the electron transfer of tetraketones with U(VI)ZU(V) and U(IV)ZU(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 ∼ +40°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.

本文言語English
ページ(範囲)18812-18820
ページ数9
ジャーナルJournal of Physical Chemistry C
111
50
DOI
出版ステータスPublished - 2007 12 20

ASJC Scopus subject areas

  • 電子材料、光学材料、および磁性材料
  • エネルギー(全般)
  • 物理化学および理論化学
  • 表面、皮膜および薄膜

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