1. Department of Chemistry Bielefeld University; P.O. Box 100131; 33501; Bielefeld; Germany
2. Department of Chemistry and Technologies of Drug; Sapienza-University of Rome; Piazzale Aldo Moro, 5; 00185; Rome; Italy
3. Department of Chemistry; L'Aquila University; Via Vetoio s.n.c. Coppito; L'Aquila; Italy