Spectroscopic Studies of Complexation Behaviour of Uranium(VI) by Schiff Bases


Spectroscopic Studies of Complexation Behaviour of Uranium(VI) by Schiff Bases

Lindner, K.; Günther, A.; Bernhard, G.

Uranium can be released into the natural environment especially from mining areas by weathering, erosion and anthropogenic activities as well as by nuclear incidents and thus represents a hazard potential for humans. New supramolecular complexing agents with N, O, S donor function are developed for the use in nuclear field and environmental protection to separate the metals of the d- and f-block and thus to clean contaminated areas. An essential basic component of these new organic ligands are Schiff bases.
In this study the complexation of uranium(VI) with Schiff bases N-benzylideneaniline (NBA), 2-(2-hydroxybenzylidenamino)phenol (HBAP) and alpha-(4-hydroxyphenylimino)-p-cresol (HPIC) was investigated in alcoholic solution using the UV-vis spectroscopy and time-resolved laser fluorescence spectroscopy with ultrashort laser pulses (fs-TRLFS). Through the change of the absorption or emission properties of organic ligands can be observed the complexation with uranium(VI).
The complexation of uranium(VI) with NBA was observed by a hypsochromic shift in the NBA band to 237 nm with the UV-vis spectroscopy. Investigations with the ligand HBAP show a bathochromic shift to 281 nm. The UV-vis absorption spectra of HPIC with uranium(VI) show no spectral shift, but a decrease in intensity of the double band at 283nm and 332 nm in comparison to the free ligand. All three ligands form complexes MLx with more ligand molecules (x=2,3).
The fs-TRLFS as a sensitive speciation technique was used to determine the luminescence properties of formed complexes in the uranium(VI)-NBA, uranium(VI)-HBAP and uranium(VI)-HPIC systems. The emission signals had a hypsochromic, bathochromic and hypsochromic shift in comparison to the emission maxima of the uncomplexed ligand. This fs-TRLFS investigation opens up the possibilities for the determination of very short-lived complex species via the fluorescence of the organic compounds by delocalized -electron systems. The calculation of corresponding complex formation constants is shown and discussed.

Keywords: Uranium(VI); Schiff Bases; fs-TRLFS; UV-vis

  • Open Access Logo Contribution to proceedings
    EuCheMS International Conference on Nuclear and Radiochchemistry (NRC-8), 16.-21.09.2012, Como, Italien
  • Poster
    EuCheMS International Conference on Nuclear and Radiochchemistry (NRC-8), 16.-21.09.2012, Como, Italien

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Publ.-Id: 17591