title: The Role of Coordination Environment and pH in Tuning the Oxidation Rate of Europium(II).
abstract: The EuII/IIIredox couple offers metal-based oxidation-sensing with magnetic resonance imaging making the study of EuIIoxidation chemistry important in the design of new probes. Accordingly, we explored oxidation reactions with a set of EuII-containing complexes. Superoxide formation from the reaction between EuIIand dioxygen was observed using electron paramagnetic resonance spectroscopy. Additionally, oxidation kinetics of three EuII-containing complexes with bromate and glutathione disulfide at pH values, including 5 and 7, is reported. In the reaction with bromate, the oxidation rate of two of the complexes increased by 7.3 and 6.7 times upon decreasing pH from 7 to 5, but the rate increased by 17 times for a complex containing amide functional groups over the same pH range. The oxidation rate of a fluorobenzo-functionalized cryptate was relatively slow, indicating that the ligand used to impart thermodynamic oxidative stability might also be useful for controlling oxidation kinetics.
authors.affiliation: Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, MI, 48202, USA.
authors.forename: Levi A
authors.identifier: http://orcid.org/0000-0001-8131-1641
authors.initials: LA
authors.lastname: Ekanger
authors.affiliation: Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, MI, 48202, USA.
authors.forename: Lina A
authors.identifier: http://orcid.org/0000-0002-4942-7844
authors.initials: LA
authors.lastname: Basal
authors.affiliation: Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, MI, 48202, USA.
authors.forename: Matthew J
authors.identifier: http://orcid.org/0000-0002-6868-8759
authors.initials: MJ
authors.lastname: Allen
keywords: chelates; imaging agents; kinetics; lanthanides; redox chemistry