1. Department of Chemistry, Hanoi University of Sciences, 19 Le Thanh Tong, Hanoi, Vietnam
2. Freie Universität Berlin, Institute of Chemistry and Biochemistry, Fabeckstrasse 34-36, D-14195 Berlin, Germany
3. Instituto de Química de São Carlos, Universidade de São Paulo, CP 780 São Carlos − São Paulo, Brazil
4. Institute of Pharmacy, Königin-Luise-Strasse 2 and 4, 14195 Berlin, Germany