Complexation of Eu(III) and Cm(III) by EGTA related aminopolycarboxylic acids

For radiation protection and chelation therapy, aminopolycarboxylic acids like ethylenedia-minetetraacetic acid (EDTA) or diethylenetriaminepentaacetic acid (DTPA) are clinical approved decorporation agents. They show promising results in complexation of Ln(III)/An(III). For EDTA and DTPA related compound ethylene glycol-bis(β-aminoethyl ether)-N,N,N’,N’-tetraacetic acid (EGTA), complexes with trivalent europium (Eu) have been characterized by NMR spectroscopy and x-ray diffraction. In these complexes, EGTA acts as an octadentate lig-and.[1,2] In addition to this, the knowledge on the Eu-EGTA-system is extended by time-resolved laser-induced fluorescence spectroscopy (TRLFS), ²H-NMR spectroscopy and isother-mal titration calorimetry (ITC). These speciation studies on Eu(III) show promising results for EGTA as a complexing agent (Fig. 1).
To expand this group of ligands, EGTA related compounds were synthesized (Fig. 2). With these compounds, the complexation behavior with Eu(III) and curium(III) were determined and com-prehensively characterized with TRLFS from both sides: the ligands and metals perspective. The overall goal is a better understanding of the influence of the ligand design on the affinity to complex trivalent Ln and An. Hence, in the future these ligands may contribute to an advanced chelation therapy.
This work is funded by the German Federal Ministry of Education and Research (BMBF) under grant number 02NUK057A and part of the joint project RADEKOR.