1. Instituto de QuímicaUniversidade de São Paulo Av. Prof. Lineu Prestes 05508-080 São Paulo – SP Brazil
2. Chemistry departamentKøbenhavn Universitet Universistetsparken 5 2100 Copenhagen, Denmark
3. Present address: Department of Chemistry and BiochemistryUniversität Bern Freiestrasse 3 CH – 3012 Bern Switzerland