1. Drug Research Program and Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, P.O. Box 56, FI-00014 Helsinki, Finland
2. Institute of Inorganic and Analytical Chemistry, University of Münster, Corrensstraße 48, 48149 Münster, Germany
3. Department of Chemistry, Faculty of Science, University of Helsinki, P.O. Box 55, FI-00014 Helsinki, Finland