Protein binding regulates complex configuration: comparative analysis of three dynamically racemic europium(iii)
Huishan Li1, Dominic J Black2, Robert Pal2
1Department of Chemistry, Hong Kong Baptist University Kowloon Tong Hong Kong SAR China davidparker@hkbu.edu.hk.
RSC Advances
|May 20, 2026
Summary
Europium complexes show poor water solubility due to aggregation. Hydrogencarbonate addition improves solubility and forms stable adducts, with different serum albumins selectively binding specific enantiomers.
Area of Science:
- Coordination Chemistry
- Supramolecular Chemistry
- Luminescence Spectroscopy
Background:
- Dynamically racemic lanthanide complexes, specifically Eu(iii) with heptadentate triazacyclononane ligands, present challenges in aqueous media.
- Understanding their aggregation behavior and solubility is crucial for potential applications in solution.
Purpose of the Study:
- To investigate the binding behavior and aqueous solution properties of three dynamically racemic Eu(iii) complexes.
- To explore strategies for enhancing water solubility and understand interactions with biomolecules like serum albumin.
Main Methods:
- Luminescence spectroscopy was employed to study the europium complexes.
- Circularly polarized luminescence (CPL) spectroscopy was used to differentiate enantiomers and analyze binding events.
Main Results:
- Low water solubility was attributed to intermolecular carboxylate ligation leading to oligomerization.
- Hydrogencarbonate addition enhanced solubility by forming a stable, reversible 1:1 ternary adduct.
- Selective binding of Λ or Δ enantiomers by human serum albumin and bovine serum albumin, respectively, was observed via CPL.
Conclusions:
- The solubility and aggregation of these Eu(iii) complexes are directly influenced by solution conditions and ligand interactions.
- Hydrogencarbonate acts as an effective solubilizing agent, forming well-defined adducts.
- Serum albumins exhibit enantioselective recognition of the europium complexes, highlighting potential for chiral sensing applications.
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