Ph.D. topics

Synthesis and characterization of actinide complexes with biologically inspired model ligands

Till Sawallisch

Prof. Dr. Thorsten Stumpf, Dr. Robert Gericke (HZDR)

Chemistry of the f-elements

11/2023-11/2026

Although the use of nuclear energy in Germany has come to an end with the nuclear phase-out, the treatment of the remaining radionuclides, such as their disposal in a final repository, continues to pose a challenge. The radioactive heavy metals of the actinides, essentially thorium, uranium, neptunium and plutonium, as well as their possible mobilization and release into the environment play a particularly important role in this. This mobilization can occur, for example, through the interaction of these metal ions with organic ligands in biological systems, which are the focus of this work.

As many of the possible ligand systems present in the environment are too complex to allow chemical characterization, small molecular model systems are to be developed instead, whose coordinating structural motifs are also important in biological systems. These include oxygen- and nitrogen-containing functional groups such as carboxylic acid amides, but softer donor atoms such as phosphorus can also play a role. These ligands are reacted with the actinides to form organometallic model complexes, which provide an insight into possible interaction modes in the environment and also contribute to research into the fundamental chemical properties of actinide metals, which are still poorly understood. Of particular interest is the synthesis of isostructural compounds of the elements thorium, uranium, neptunium and plutonium with the same ligand systems, which can reveal differences and trends in the coordination chemistry of these elements. The synthesized complexes are therefore comprehensively characterized using various spectroscopic and analytical methods in the solid state and in solution, including XRD, NMR, IR, XAS, SQUID, MS and EA. These results can then be compared and supplemented with quantum chemical calculations.

This work is part of the joint project “FENABIUM II” (Investigations on the interactions of f-elements with biologically relevant structural motifs: Derivation of fundamental structure-activity principles for mobilization in the environment), which is funded by the German Federal Ministry of Education and Research under grant number 02NUK077B.