1. Cardinal Stefan Wyszyński University, College of Science,Department of Mathematics & Natural Science, Dewajtis 5, 01‐815 Warszawa, Poland
2. Institute of Organic Chemistry Polish Academy of Sciences, Kasprzaka 44/52, 01‐224 Warszawa, Poland
3. Department of Chemistry, Warsaw University, Pasteura 1, 02‐093 Warszawa, Poland, Fax: +48‐22‐8220211 ext. 345
4. Department of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00‐664 Warszawa, Poland