Spectroscopic, electrochemical, and structural aspects of the Ce(IV)/Ce(III) DOTA redox couple chemistry in aqueous solutions

Yulia Moiseev, Yeshayahu Ben-Eliyahu, Matthieu Audras, Laurence Berthon, Philippe Moisy, Armand Bettelheim, Israel Zilbermann

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

The redox potential of the Ce(IV)/Ce(III) DOTA is determined to be 0.65 V versus SCE, pointing out a stabilization of ~13 orders of magnitude for the Ce(IV)DOTA complex, as compared to Ce(IV)aq. The Ce(III)DOTA after electrochemical oxidation yields a Ce(IV)DOTA complex with a t1/2 ~3 h and which is suggested to retain the “in cage” geometry. Chemical oxidation of Ce(III)DOTA by diperoxosulfate renders a similar Ce(IV)DOTA complex with the same t1/2. From the electrochemical measurements, one calculates logK (Ce(IV)DOTA2−) ~ 35.9. Surprisingly, when Ce(IV)DOTA is obtained by mixing Ce(IV)aq with DOTA, a different species is obtained with a 2 : 1(M : L) stoichiometry. This new complex, Ce(IV)DOTACe(IV), shows redox and spectroscopic features which are different from the electrochemically prepared Ce(IV)DOTA. When one uses thiosulfate as a reducing agent of Ce(IV)DOTACe(IV), one gets a prolonged lifetime of the latter. The reductant seems to serve primarily as a coordinating ligand with a geometry which does not facilitate inner sphere electron transfer. The reduction process rate in this case could be dictated by an outer sphere electron transfer or DOTA exchange by S2O3 2−. Both Ce(IV)DOTA and Ce(IV)DOTACe(IV) have similar kinetic stability and presumably decompose via decarboxylation of the polyaminocarboxylate ligand.

Original languageEnglish
Pages (from-to)2895-2907
Number of pages13
JournalJournal of Coordination Chemistry
Volume69
Issue number19
DOIs
StatePublished - 1 Oct 2016

Keywords

  • DOTA
  • cerium(III) complex
  • cerium(IV) complex
  • polyaminocarboxylate
  • redox
  • spectroscopy

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Materials Chemistry

Fingerprint

Dive into the research topics of 'Spectroscopic, electrochemical, and structural aspects of the Ce(IV)/Ce(III) DOTA redox couple chemistry in aqueous solutions'. Together they form a unique fingerprint.

Cite this