Article, 2024

Using Chiral Auxiliaries to Mimic the Effect of Chiral Media on the Structure of Lanthanide(III) Complexes Common in Bioimaging and Diagnostic MRI

Inorganic Chemistry, ISSN 0020-1669, 1520-510X, Volume 63, 17, Pages 7560-7570, 10.1021/acs.inorgchem.3c01589

Contributors

Nielsen, Lea Gundorff 0000-0001-7879-6115 [1] Andersen, Helene Obel Bøch [1] Kenwright, Alan M 0000-0002-7169-7103 [2] Platas-Iglesias, Carlos 0000-0002-6989-9654 [3] So̷rensen, Thomas Just (Corresponding author) [1]

Affiliations

  1. [1] University of Copenhagen
  2. [NORA names: KU University of Copenhagen; University; Denmark; Europe, EU; Nordic; OECD];
  3. [2] Durham University
  4. [NORA names: United Kingdom; Europe, Non-EU; OECD];
  5. [3] University of A Coruña
  6. [NORA names: Spain; Europe, EU; OECD]

Abstract

[Ln·DOTA]- complexes and systems derived therefrom are commonly used in MRI and optical bioimaging. These lanthanide(III) complexes are chiral, and, in solution, they are present in four forms, with two sets of enantiomers, with the ligand donors arranged in either a square antiprismatic, SAP, or twisted square antiprismatic geometry, TSAP. This complicated speciation is found in laboratory samples. To investigate speciation in biological media, when Ln·DOTA-like complexes interact with chiral biomolecules, six Eu·DOTA-monoamide complexes were prepared and investigated by using 1D and 2D 1H NMR. To emulate the chirality of biological media, the amide pendant arm was modified with one or two chiral centers. It is known that a chiral center on the DOTA scaffold significantly influences the properties of the system. Here, it was found that chirality much further away from the metal center changes the available conformational space and that both chiral centers and amide cis/trans isomerism may need to be considered─a fact that, for the optically enriched materials, led to the conclusion that eight chemically different forms may need to be considered, instead of the four forms necessary for DOTA. The results reported here clearly demonstrate the diverse speciation that must be considered when correlating an observation to a structure of a lanthanide(III) complex.

Keywords

DOTA, DOTA scaffold, MRI, TSAP, amide, amide pendant arms, arm, auxiliary, bioimaging, biological media, biomolecules, center, chemical, chemically different forms, chiral auxiliary, chiral biomolecules, chiral centers, chiral media, chirality, complex, complicated speciation, conformational space, diagnostic MRI, diagnostics, diverse speciation, donor, effect, enantiomers, form, geometry, investigate speciation, isomerization, laboratory, laboratory samples, lanthanide(III, lanthanide(III) complexes, ligand, ligand donors, materials, media, medium, metal, metal center, observations, optical bioimaging, pendant arms, properties, results, samples, sap, scaffolds, sets, sets of enantiomers, solution, space, speciation, square antiprismatic geometry, structure, system

Funders

  • Carlsberg Foundation
  • Ministry of Economy, Industry and Competitiveness
  • Novo Nordisk Foundation
  • European Commission
  • The Velux Foundations

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