Vibrational spectroscopy of actinyl complexes


Vibrational spectroscopy of actinyl complexes

Müller, K.; Li, B.

Vibrational spectroscopy potentially provides structural information of molecule complexes. Actinyl ions, e.g. AnO2 n+ (An=U,Np; n=1,2) can be identified by the frequency of their antisymmetric stretching vibrational mode νas which generally correlates with the character of the molecular environment, i.e. number and type of ligand, of the actinyl ion group. [1]
The migration behavior of actinides in the geosphere is strongly influenced by sorption processes at water-mineral oxide interfaces [2]. The sorption of neptunium(V) at low concentration levels (50 μM) on model oxide surfaces (TiO2, SiO2, ZnO) was investigated in situ at different pH (4.0 – 7.6). For the first time, in situ formation of inner-sphere bidentate Np(V) surface complexes onto oxides was observed by FT-IR spectroscopy [3]. Unequivocal assignments of thermodynamic reaction constants are feasible.
To investigate the U(VI) chemotoxicity at a molecular level, the coordination between U(VI) and different protein functional groups under
physiological relevant conditions is investigated.The highly phosphorylated protein phosvitin serves as a model system for the elucidation of the molecular interaction of uranyl with native proteins in aqueous solution. [4,5] Soluble protein-U(VI) complexes in aqueous solution evidence preferential U(VI) complexation to phosphoryl groups of the protein side chains. In combination with X-ray spectroscopy molecular structures such as the postulated “Feldman complex” can be verified [6].

[1] K. Müller, H. Foerstendorf, S. Tsushima, V. Brendler, G. Bernhard (2009), Journal of Physical Chemistry A 113, 6626-6632.
[2] G. R. Choppin (2007), Journal of Radioanalytical and Nuclear Chemistry 273, 695-703
[3] K. Müller, H. Foerstendorf, V. Brendler, G. Bernhard (2009) Environmental Science & Technology, 43, 7665-7670
[4] R. Shainkin, G.E. Perlmann (1971) Journal of Biological Chemistry 246, 2278-2284.
[5] B.M. Byrne, A.D.V. Schip, J.A.M. Vandeklundert, A.C. Arnberg, M. Gruber, G. Ab (1984) Biochemistry 23, 4275-4279.
[6] B. Li, H. Foerstendorf, J. Raff, G. Bernhard (2007) Geochim. Cosmochim. Acta 71, A567.

  • Poster
    FZD PhD-Seminar 2009, 16.-18.09.2009, Krögis, Deutschland

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