Counterintuitive Impact of Polar Solubilizing Group Functionalization on Ligand Solubility and f-Block Element...

Area of Science:

• Coordination Chemistry
• Supramolecular Chemistry
• Radiopharmaceutical Chemistry

Background:

• Designing multidentate hydrophilic ligands is crucial for metal separation and radiopharmaceuticals.
• A common strategy is adding water-solubilizing groups to lipophilic ligands, but this can fail without proper hydrogen bonding.

Purpose of the Study:

• To investigate how hydrogen bonding influences water solubility and metal affinity in ligand design.
• To reveal the molecular mechanisms behind the success or failure of hydrophilic ligand design.

Main Methods:

• Utilized a phenanthroline diimine ligand system as a model.
• Employed spectroscopic titrations, single-crystal X-ray diffraction, and Density Functional Theory (DFT) calculations.

Main Results:

• Demonstrated that inter- and intramolecular hydrogen bonding critically impacts ligand water solubility and metal affinity.
• Provided molecular-level insights into the role of hydrogen-bonding networks.

Conclusions:

• The intuitive approach of adding solubilizing groups may fail if hydrogen bonding is not optimized.
• This study offers guidance for rational hydrophilic ligand design for applications in metal separation and radiopharmaceuticals.