1. Faculty of Science, University of Kinshasa, B.P. 190 Kinshasa XI, D. R.
Congo
2. Department
of Chemistry, University of Leuven, Celestijnenlaan 200F, 3001 Heverlee, Belgium
3. Department of General Chemistry
(ALGC), Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium