Synthesis and structural characterization of the first neptunium based metal-organic frameworks incorporating {Np₆O₈}...

Area of Science:

• Radiochemistry
• Materials Science
• Inorganic Chemistry

Background:

• Transuranium elements present unique challenges in materials synthesis due to their radioactivity and complex chemistry.
• Metal-organic frameworks (MOFs) offer versatile platforms for incorporating diverse metal ions, but their application to transuranium elements remains underexplored.

Purpose of the Study:

• To report the successful synthesis and structural characterization of the first transuranium metal-organic frameworks (TRU-MOFs) incorporating tetravalent neptunium (Np4+).
• To investigate the coordination chemistry of Np4+ within a framework structure.

Main Methods:

• Controlled hydrolysis of Np4+ ions in aqueous solution.
• Crystallization in the presence of ditopic dicarboxylate ligands.
• Single-crystal X-ray diffraction for structural determination.

Main Results:

• The first synthesis of TRU-MOFs containing tetravalent neptunium (Np4+) was achieved.
• The resulting structures feature a novel [Np6O4(OH)4(H2O)6]12+ cluster unit, previously unobserved for Np4+.
• These clusters are linked by ditopic ligands, forming extended framework architectures.

Conclusions:

• This work demonstrates the feasibility of constructing MOFs with tetravalent neptunium.
• The discovery of the [Np6O4(OH)4(H2O)6]12+ unit expands the known coordination chemistry of neptunium.
• These findings open new avenues for exploring the materials science of actinide-based frameworks.