Tuning Lanthanide Binding with Phenanthroline-Based Diamides via Electron-Donating and Electron-Withdrawing Groups

Area of Science:

• Inorganic Chemistry
• Computational Chemistry
• Separation Science

Background:

• Efficient separation of lanthanides is a persistent challenge due to their similar chemical properties.
• 1,10-phenanthroline-2,9-diamide (DAPhen) ligands show promise for solvent extraction of f-elements.
• Tuning electronic properties of DAPhen ligands for lanthanide complexation remains underexplored.

Purpose of the Study:

• To investigate the impact of electron-donating and electron-withdrawing substituents on the phenanthroline skeleton of DAPhen ligands.
• To assess how these modifications affect complexation properties relevant to lanthanide separation.
• To provide a theoretical understanding of substituent effects on lanthanide binding.

Main Methods:

• Advanced quantum chemical calculations were employed.
• The study focused on DAPhen ligands with various substituents on the phenanthroline core.
• Binding energies and selectivity were analyzed for lanthanide complexes.

Main Results:

• Substitutions on the phenanthroline skeleton significantly altered binding energies with lanthanides.
• The influence of these substituents on selectivity across the entire lanthanide series was relatively weak.
• Elucidation of bonding nature provided insights into substituent effects.

Conclusions:

• Electron-donating and electron-withdrawing groups play a crucial role in modulating lanthanide binding energies.
• These findings offer valuable guidelines for the rational design of novel DAPhen-based ligands.
• The study contributes to improving rare-earth element separation technologies.