Curium(III) complexation with desferrioxamine B (DFO) investigated using fluorescence spectroscopy

Hydroxamate-type siderophores like desferrioxamine B (DFO) are the most common siderophores ubiquitously found in the environment. These naturally occurring chelating substances have the potential to enhance the solubility and mobility of actinides by forming soluble complexes. The unknown interaction between curium(III) and the aqueous DFO species is the subject of this paper. The interaction between soluble species of curium(III) and DFO was studied at trace curium(III) concentrations (3 x 10-7 M) using time-resolved laser-induced fluorescence spectroscopy (TRLFS). Three Cm3+ - DFO species, MpHqLr, could be identified from the luminescence spectra, CmH2DFO2+, CmHDFO+, and CmDFB, having emission maxima at 599, 611, and 614 nm, respectively. The as well large formation constants, log β121 = 31.62 ± 0.23, log β111 = 25.70 ± 0.17, and log β101 = 16.80 ± 0.40, compared to those of other chelating agents illustrate the unique complexation properties of hydroxamate-type siderophores. An indirect excitation mechanism for the curium(III) luminescence was observed in the presence of the DFO molecules.