Crystallographic Characterization and Non‐Innocent Redox Activity of the Glycine Modified DOTA Scaffold and Its Impact on EuIII Electrochemistry

EuDOTA‐glycine derivatives have been explored as alternatives to typical gadolinium‐containing complexes for MRI agents used in diagnostic imaging. Different imaging modalities can be accessed (T1 or PARACEST) dependent on the oxidation state of the europium ion. Throughout the past 30 years, there...

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Bibliographic Details
Published in:European journal of inorganic chemistry 2018-04, Vol.2018 (14), p.1556-1562
Main Authors: Burnett, Marianne E., Adebesin, Bukola, Ratnakar, S. James, Green, Kayla N.
Format: Article
Language:English
Subjects:
Crystallography
Cyclic voltammetry
Derivatives
Diagnostic systems
DOTA
Electrochemical analysis
Electrochemistry
Electrodes
Europium
Gadolinium
Glassy carbon
Glycine
Imaging agents
Inorganic chemistry
Ligand effects
Ligands
Magnetic resonance imaging
Oxidation
Scaffolds
Substitutes
Valence
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Summary:EuDOTA‐glycine derivatives have been explored as alternatives to typical gadolinium‐containing complexes for MRI agents used in diagnostic imaging. Different imaging modalities can be accessed (T1 or PARACEST) dependent on the oxidation state of the europium ion. Throughout the past 30 years, there have been significant manipulations and additions made to the DOTA scaffold; yet, characterizations related to electrochemistry and structure determined through XRD analysis have not been fully analyzed. In this work, electrochemical analysis using cyclic voltammetry was carried out on EuDOTA derivatives, including the free ligand DOTAGly4 (4) and the complexes. Effects of glycinate substitution on the DOTA scaffold, specifically, ligand interactions with the glassy carbon electrode were observed. A range of electrochemical investigations were carried out to show that increased glycinate substitution led to increased interaction with the electrode surface, thus implicating a new factor to consider when evaluating the electrochemistry of glycinate substituted ligands. In addition, the solid‐state structure of EuDOTAGly4 (Eu4) was determined by X‐ray diffraction and a brief analysis is presented compared to known Ln3+ structures found within literature. The Eu4 complex crystalizes in a rare polymer type arrangement via bridging side‐arms between adjacent complexes. Electrochemical analysis of DOTAglycine derivatives demonstrate that the non‐innocent ligand behavior increases with glycine substitution to DOTA; Solid‐state structure analysis of Eu4 indicates a square antiprism (SAP) geometry and unique intermolecular interactions.
ISSN:1434-1948
1099-0682
DOI:10.1002/ejic.201701398