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

For purposes of chelation therapy and radiation protection, aminopolycarboxylic acids like ethylenediaminetetraacetic acid (EDTA) or diethylenetriaminepentaacetic acid (DTPA) are clinical approved decorporation agents against lanthanides (Ln) and actinides (An). This well known group of chelating agents shows 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 ligand.[1][2] In this work the knowledge on the Eu-EGTA-system is extended by time-resolved laser-induced fluorescence spectroscopy (TRLFS), electrospray ionization mass spectrometry (ESI-MS) and isothermal titration calorimetry (ITC). These speciation studies on Eu(III) show promising results for EGTA as complexing agent.
To expand this ligand group, EGTA related ligands are synthesized. With these compounds, the complexation behaviour towards Eu(III) and curium(III) are determined and comprehensively characterised from both the ligands and metals perspective with TRLFS, NMR spectroscopy, single crystal x-ray diffraction and fourier-transform infrared spectroscopy. The overall goal is a better understanding between ligand design and affinity to trivalent lanthanides and actinides. Hence, in the future these ligands may contribute to chelation therapy as decorporation agents.
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.

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[2]. R. Xu, D. Li, J. Wang, Y. X. Kong, B. X. Wang, Y. M. Kong, T. T. Fan, B. Liu, Russ. J. Coord. Chem. 2010, 36, 810.